Title: Working machine having a single operation unit
Abstract: The present invention provides a working machine having an internal combustion engine. The working machine includes a single operation unit comprised of a rotatable body adapted to be selectively rotated between an engine-stop position, engine-start position and choke-activation position, a valve to be rotated about an rotation shaft, an arm attached to the rotation shaft and a link member adapted to be moved in its longitudinal direction to transmit the movement of the rotatable body to the arm. The link member has a distal end coupled with the arm and a proximal end coupled with the rotatable body, and extends between the distal and proximal ends. The rotatable body is formed with an elongated slot receiving the proximal end therein. When the rotatable body is rotated from the engine-stop position to the engine-start position, the proximal end is allowed to displace relative to the rotatable body along the elongated slot without causing any movement of the link member in the longitudinal direction. When the rotatable body is rotated from the engine-start position to the choke-activation position, the proximal end is restricted in its displacement along the elongated slot so that the link member is moved in the longitudinal direction to transmit the movement of the rotatable body to the arm.
Patent Number: 6,871,623 Issued on 03/29/2005 to Ohsawa, et al.
| Inventors:
|
Ohsawa; Hisato (Fussa, JP);
Tajima; Katsuya (Okayama, JP);
Kobayashi; Fujio (Hachioji, JP)
|
| Assignee:
|
Kioritz Corp. (Tokyo, JP)
|
| Appl. No.:
|
273287 |
| Filed:
|
October 18, 2002 |
Foreign Application Priority Data
| Oct 19, 2001[JP] | 2001-322333 |
| Current U.S. Class: |
123/179.18; 261/52 |
| Intern'l Class: |
F02M 001//00 |
| Field of Search: |
123/179.18,179.5,179.16
261/52
|
References Cited [Referenced By]
U.S. Patent Documents
| 4079708 | Mar., 1978 | Wieland et al. | 123/376.
|
| 5215049 | Jun., 1993 | Wolf | 123/179.
|
| 5693264 | Dec., 1997 | Fricke | 261/64.
|
| 5927241 | Jul., 1999 | Dahlberg et al. | 123/179.
|
Primary Examiner: Gimie; Mahmoud
Assistant Examiner: Castro; Arnold
Attorney, Agent or Firm: Nixon Peabody, LLC, Studebaker; Donald R.
Claims
What is claimed is:
1. A working machine including an internal combustion engine, said working
machine comprising:
a single operation unit for switching between stop, start and choke
operations of said engine, said operation unit including a rotatable body
capable of being rotationally moved according to a manual operation;
a choke open/close mechanism for an intake system of said engine, said
choke open/close mechanism including a choke valve, a choke shaft for
rotating said choke valve, and an arm attached to said choke shaft; and
a choke-activating link member adapted to be moved in its longitudinal
direction to transmit the movement of said rotatable body to said arm so
as to close said choke valve, said choke-activating link member having a
distal end coupled with said arm and a proximal end coupled with said
rotatable body and extending between said distal and proximal ends,
wherein
said rotatable body is adapted to be switchably moved in turn from a first
rotational position for stopping said engine, through a second rotational
position for allowing said engine to be started, to a third rotational
position for activating said choke open/close mechanism, and
said rotatable body is formed with an elongated slot which receives therein
said proximal end such that when said rotatable body is rotated from said
first rotational position to said second rotational position, said
proximal end is allowed to displace relative to said rotatable body along
said elongated slot without causing any movement of said choke-activating
link member in said longitudinal direction, and when said rotatable body
is rotated from said second rotational position to said third rotational
position, said proximal end is restricted in its displacement along said
elongated slot so that said choke-activating link member is moved in said
longitudinal direction in response to the rotational movement of said
rotatable body to transmit the movement of said rotatable body to said
arm.
2. A working machine including an internal combustion engine serving as a
power source therefor, said working machine comprising:
a single operation unit for switching between stop, start and choke
operations of said engine, said operation unit including a rotatable body
capable of being rotationally moved according to a manual operation;
a choke open/close mechanism for an intake system of said engine, said
choke open/close mechanism including a choke valve, a choke shaft for
rotating said choke valve, and an arm fixedly attached to said choke
shaft; and
a choke-activating link member adapted to be moved in its longitudinal
direction to transmit the movement of said rotatable body to said arm so
as to close said choke valve, said choke-activating link member having a
distal end coupled with said arm and a proximal end coupled with said
rotatable body and extending between said distal and proximal ends,
wherein
said rotatable body is adapted to be switchably moved in turn from a first
rotational position for stopping said engine, through a second rotational
position for allowing said engine to be started, to a third rotational
position for activating said choke open/close mechanism, and
said rotatable body is formed with an elongated slot which receives therein
said proximal end such that when said rotatable body is rotated from said
first rotational position to said second rotational position, said
proximal end is allowed to displace relative to and in the radial
direction of said rotatable body along said elongated slot so as to cause
a swing movement of said choke-activating link member about said distal
end, and when said rotatable body is rotated from said second rotational
position to said third rotational position, said proximal end is
restricted in its displacement along said elongated slot so that said
choke-activating link member is moved in said longitudinal direction in
response to the movement of said rotatable body to transmit the movement
of said rotatable body to said arm.
3. A working machine including an internal combustion engine serving as a
power source therefor, said working machine comprising:
a single operation unit for switching between stop, start and choke
operations of said engine, said operation unit including a rotatable body
capable of being rotationally moved according to a manual operation;
a choke open/close mechanism for an intake system of said engine, said
choke open/close mechanism including a choke valve, a choke shaft for
rotating said choke valve, and an arm attached to said choke shaft; and
a choke-activating link member adapted to be moved in its longitudinal
direction to transmit the movement of said rotatable body to said arm so
as to close said choke valve, said choke-activating link member having a
distal end coupled with said arm and a proximal end coupled with said
rotatable body, said choke-activating link member extending in the
crosswise direction with respect to said distal and proximal ends
therebetween, wherein
said rotatable body is adapted to be switchably moved in turn from a first
rotational position for stopping said engine, through a second rotational
position for allowing said engine to be started, to a third rotational
position for activating said choke open/close mechanism, and
said rotatable body is formed with an elongated slot extending in said
crosswise direction, said elongated slot having a leading end zone located
on a leading side with respect to the rotation direction of said rotatable
body and a trailing end zone located on a trailing side with respect to
said rotation direction, wherein
said rotatable body is adapted to receive therein said proximal end such
that:
when said rotatable body is located at said first rotational position, said
proximal end is located in said leading end zone;
when said rotatable body is rotated from said first rotational position to
said second rotational position, said proximal end is moved from said
leading end zone to said trailing end zone while displacing relative to
and in the radial direction of said rotatable body along said elongated
slot to cause a swing movement of said choke-activating link member about
said distal end; and
when said rotatable body is rotated from said second rotational position to
said third rotational position, said proximal end is held in said trailing
end zone so that said choke-activating link member is pushed in said
longitudinal direction in response to the movement of said rotatable body
to transmit the movement of said rotatable body to said arm.
4. The working machine as defined in either one of claims 1 to 3, further
comprising:
a throttle open/close mechanism for opening and closing a throttle valve of
said intake system;
an interlock mechanism for interlocking said throttle open/close mechanism
and said choke open/close mechanism; and
a release mechanism including a release lever for releasing said interlock
mechanism.
5. The working machine as defined in claim 4, wherein said operation unit
and said release lever are disposed at the front end portion of a handle
extending in the lengthwise direction of said working machine.
6. The working machine as defined in claim 4, wherein said choke open/close
mechanism, said throttle open/close mechanism and said interlock mechanism
are housed in an interior space of the rear end portion of said handle.
7. The working machine as defined in claim 4, wherein said choke-activating
link member is comprised of a rod-shaped member extending from said
rotatable body to said arm attached to said choke shaft, in said
lengthwise direction through the internal space of said handle.
8. The working machine as defined in claim 4, wherein said release
mechanism includes a rod-shaped throttle-releasing link member having a
proximal end coupled with said release lever and a distal end coupled with
said interlock mechanism, said throttle-releasing link member extending in
said longitudinal direction through the interior space of said handle
along said choke-activating link member.
9. The working machine as defined in claim 3, wherein said operation unit
further includes a guide portion for guiding said proximal end of said
choke-activating link member from said leading end zone to said trailing
end zone along said elongated slot when said rotatable body is moved from
said first rotational position to said second rotational position, and for
holding said proximal end of said choke-activating link member in said
trailing end zone when said rotatable body is moved from said second
rotational position to said third rotational position.
10. The working machine as defined in claim 9, wherein said rotatable body
has a substantially circular shape, wherein said leading end zone is
located inward in the radial direction and on the leading side of said
rotatable body, and said trailing end zone is located outward in the
radial direction and on the trailing side of said rotatable body, said
trailing end zone being spaced apart from the rotation center of said
rotatable body by a first radial distance, and said elongated slot
extending obliquely with respect to said radial direction from said
leading end zone to said trailing end zone.
11. The working machine as defined in claim 10, wherein said guide portion
has a flat surface region extending straight in the radial direction of
said rotatable body up to a position of a second radial distance derived
by subtracting the outside dimension of said proximal end of said
choke-activating link member from said first radial distance, and an arc
surface region extending from the radially outer end of said flat surface
region to the leading side of the rotatable body to form an arc having a
radius of said second radial distance about said rotation center, wherein
when said rotatable body is located at said first rotational position, said
proximal end of said choke-activating link member is located in said
elongated slot on the trailing side with respect to said flat surface
region, and
when said rotatable body is moved from said first rotational position to
said third rotational position, said proximal end of said choke-activating
link member is moved along said flat surface and arc surface regions.
12. The working machine as defined in claim 4, wherein said operation unit
further includes a guide portion for guiding said proximal end of said
choke-activating link member from said leading end zone to said trailing
end zone along said elongated slot when said rotatable body is moved from
said first rotational position to said second rotational position, and for
holding said proximal end of said choke-activating link member in said
trailing end zone when said rotatable body is moved from said second
rotational position to said third rotational position.
13. The working machine as defined in claim 12, wherein said rotatable body
has a substantially circular shape, wherein said leading end zone is
located inward in the radial direction and on the leading side of said
rotatable body, said trailing end zone being located outward in the radial
direction and on the trailing side of said rotatable body, said trailing
end zone being spaced apart from the rotation center of said rotatable
body by a first radial distance, and said elongated slot body extending
obliquely with respect to said radial direction from said leading end zone
to said trailing end zone.
14. The working machine as defined in claim 13, wherein said guide portion
has a flat surface region extending straight in the radial direction of
said rotatable body up to a position of a second radial distance derived
by subtracting the outside dimension of said proximal end of said
choke-activating link member from said first radial distance, and an arc
surface region extending from the radially outer end of said flat surface
region to the leading side of the rotatable body to form an arc having a
radius of said second radial distance about said rotation center, wherein
when said rotatable body is located at said first rotational position, said
proximal end of said choke-activating link member is located in said
elongated slot on the trailing side with respect to said flat surface
region, and
when said rotatable body is moved from said first rotational position to
said third rotational position, said proximal end of said choke-activating
link member is moved along said flat surface and arc surface regions.
15. The working machine as defined in either one of claims 1 to 3, further
comprising:
a throttle open/close mechanism for opening and closing a throttle valve of
said intake system;
an interlock mechanism for interlocking said throttle open/close mechanism
and said choke open/close mechanism; and
a release mechanism including a release lever for releasing said interlock
mechanism, wherein
said operation unit and said release lever are disposed at the front end
portion of a handle extending in the lengthwise direction of said working
machine,
said choke open/close mechanism, said throttle open/close mechanism and
said interlock mechanism being housed in an interior space of the rear end
portion of said handle,
said choke-activating link member being comprised of a rod-shaped member
extending from said rotatable body to said arm attached to said choke
shaft, in said lengthwise direction through the internal space of said
handle, and
said release mechanism including a rod-shaped throttle-releasing link
member having a proximal end coupled with said release lever and a distal
end coupled with said interlock mechanism, said throttle-releasing link
member extending in said longitudinal direction through the interior space
of said handle along said choke-activating link member.
16. The working machine as defined in claim 3, wherein said operation unit
further includes a guide portion for guiding said proximal end of said
choke-activating link member from said leading end zone to said trailing
end zone along said elongated slot when said rotatable body is moved from
said first rotational position to said second rotational position, and for
holding said proximal end of said choke-activating link member in said
trailing end zone when said rotatable body is moved from said second
rotational position to said third rotational position, and
said rotatable body has a substantially circular shape, wherein said
leading end zone is located inward in the radial direction and on the
leading side of said rotatable body, said trailing end zone is located
outward in the radial direction and on the trailing side of said rotatable
body, said trailing end zone being spaced apart from the rotation center
of said rotatable body by a first radial distance, and said elongated slot
body extending obliquely with respect to said radial direction from said
leading end zone to said trailing end zone, wherein
said guide portion has a flat surface region extending straight in the
radial direction of said rotatable body up to a position of a second
radial distance derived by subtracting the outside dimension of said
proximal end of said choke-activating link member from said first radial
distance, and an arc surface region extending from the radially outer end
of said flat surface region to the leading side of the rotatable body to
form an arc having a radius of said second radial distance about said
rotation center, wherein
when said rotatable body is located at said first rotational position, said
proximal end of said choke-activating link member is located in said
elongated slot on the trailing side with respect to said flat surface
region, and
when said rotatable body is moved from said first rotational position to
said third rotational position, said proximal end of said choke-activating
link member is moved along said flat surface and arc surface regions.
17. The working machine as defined in claim 15, wherein said operation unit
further includes a guide portion for guiding said proximal end of said
choke-activating link member from said leading end zone to said trailing
end zone along said elongated slot when said rotatable body is moved from
said first rotational position to said second rotational position, and for
holding said proximal end of said choke-activating link member in said
trailing end zone when said rotatable body is moved from said second
rotational position to said third rotational position, and
said rotatable body has a substantially circular shape, wherein said
leading end zone is located inward in the radial direction and on the
leading side of said rotatable body, said trailing end zone being located
outward in the radial direction and on the trailing side of said rotatable
body, said trailing end zone being spaced apart from the rotation center
of said rotatable body by a first radial distance, and said elongated slot
body extending obliquely with respect to said radial direction from said
leading end zone to said trailing end zone, wherein
said guide portion has a flat surface region extending straight in the
radial direction of said rotatable body up to a position of a second
radial distance derived by subtracting the outside dimension of said
proximal end of said choke-activating link member from said first radial
distance, and an arc surface region extending from the radially outer end
of said flat surface region to the leading side of the rotatable body to
form an arc having a radius of said second radial distance about said
rotation center, wherein
when said rotatable body is located at said first rotational position, said
proximal end of said choke-activating link member is located in said
elongated slot on the trailing side with respect to said flat surface
region, and
when said rotatable body is moved from said first rotational position to
said third rotational position, said proximal end of said choke-activating
link member is moved along said flat surface and arc surface regions.
Description
FIELD OF THE INVENTION
The present invention relates to a working machine driven by an internal
combustion engine. In particular, the present invention relates to a
working machine driven by an internal combustion engine and provided with
a single operation unit for switching between stop, start and choke
operations of the internal combustion engine.
BACKGROUND OF THE INVENTION
A working machine equipped with an internal combustion engine as a power
source typically includes a choke-valve open/close mechanism for opening
and closing a choke valve of an intake system of the engine, a
throttle-valve open/close mechanism for opening and closing a throttle
valve of the intake system, an interlock mechanism for interlocking the
choke-valve open/close mechanism and the throttle-valve open/close
mechanism, and a release mechanism for releasing the interlock mechanism.
For starting the internal combustion engine, an electric switch is moved
from a stop position to a start position to electrically turn on an
ignition unit. Additionally, if the internal combustion engine is cold,
the engine is started after activating the choke-valve open/close
mechanism to close the choke valve. In this operation, the choke-valve
open/close mechanism is interlocked with the throttle-valve open/close
mechanism by the interlock mechanism to allow the throttle valve to be
partially opened for the operation-period of the choke-valve open/close
mechanism.
For example, Japanese Patent Laid-open Publication No. 5-214972 discloses a
chain saw, as a working machine, having a single operation unit for
switching between stop, start and choke operations of an internal
combustion engine. In the working machine, the operation unit is provided
at the front end portion of a handle extending in the lengthwise direction
of the body of the working machine. Further, a choke-valve open/close
mechanism, a throttle-valve open/close mechanism and an interlock
mechanism therefor are housed in an interior space of the rear end portion
of the handle. These mechanisms are operationally coupled with the
operation unit through a link mechanism to transmit the movement of the
operation unit to the mechanisms provided at the rear end portion.
This working machine is highly advantageous in that the stop, start and
choke operations of the internal combustion engine can be switched only by
a single operation unit. However, the link mechanism provided inside the
working machine has a complicated structure, resulting in an increased
number of components, deteriorated workability during the assembly process
and increased cost.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a working
machine having a single operation unit capable of switching between stop,
start and choke operations of an internal combustion engine, with a
simplified mechanism for transmitting operational movements.
In order to achieve the above object, according to a first aspect of the
present invention, there is provided a working machine including an
internal combustion engine serving as a power source. The working machine
includes a single operation unit for switching between stop, start and
choke operations of the engine, which includes a rotatable body capable of
being rotationally moved according to a manual operation; a choke
open/close mechanism for an intake system of the engine, which includes a
choke valve, a choke shaft for rotating the choke valve, and an arm
attached to the choke shaft; and a choke-activating link member adapted to
be moved in its longitudinal direction to transmit the movement of the
rotatable body to the arm so as to close the choke valve. The
choke-activating link member has a distal end coupled with the arm and a
proximal end coupled with the rotatable body, and extends between the
distal and proximal ends. In the working machine, the rotatable body is
adapted to be switchably moved in turn from a first rotational position
for stopping the engine, through a second rotational position for allowing
the engine to be started, to a third rotational position for activating
the choke open/close mechanism. Further, the rotatable body is formed with
an elongated slot which receives therein the proximal end such that when
the rotatable body is rotated from the first rotational position to the
second rotational position, the proximal end is allowed to displace
relative to the rotatable body along the elongated slot without causing
any movement of the choke-activating link member in the longitudinal
direction. When the rotatable body is rotated from the second rotational
position to the third rotational position, the proximal end is restricted
in its displacement along the elongated slot so that the choke-activating
link member is moved in the longitudinal direction in response to the
rotational movement of the rotatable body to transmit the movement of the
rotatable body to the arm.
The working machine according the first aspect of the present invention is
operated as follows. The operation unit is first moved from the first
rotational position or an engine-stop position for stopping the internal
combustion engine to the second rotational position or an engine-start
position for starting the engine. Through this operation, an ignition unit
is turned on to allow the engine to be started. When the rotatable body is
rotated from the first rotational position to the second rotational
position, the proximal end of the choke-activating link member is allowed
to displace relative to the rotatable body along the elongated slot of the
rotatable body, that is, the proximal end of the choke-activating link
member is not displaced relative to the body of the working machine. Thus,
the choke-activating link member is not moved in the longitudinal
direction. For example, if the internal combustion engine is cold, the
operation unit will be further moved to the third position for activating
the choke open/close mechanism. When the rotatable body is rotated from
the second rotational position to the third rotational position, the
proximal end is restricted in its displacement along the elongated slot so
that the choke-activating link member is moved in the longitudinal
direction in response to the movement of the rotatable body. Thus, the arm
coupled with the distal end of the choke-activating link member is swung
to rotate the choke shaft and close the choke valve. This facilitates the
cold start of the internal combustion engine.
Thus, the first aspect of the present invention can provide a working
machine having a simplified structure for reliably transmitting the
movement of the operation unit to the choke open/close mechanism to
facilitate its assemble process and achieve reduced cost.
According to a second aspect of the present invention, there is provided a
working machine including an internal combustion engine serving as a power
source therefor. The working machine includes a single operation unit for
switching between stop, start and choke operations of the engine, which
includes a rotatable body capable of being rotationally moved according to
a manual operation; a choke open/close mechanism for an intake system of
the engine, which includes a choke valve, a choke shaft for rotating the
choke valve, and an arm attached to the choke shaft; and a
choke-activating link member adapted to be moved in its longitudinal
direction to transmit the movement of the rotatable body to the arm so as
to close the choke valve. The choke-activating link member has a distal
end coupled with the arm and a proximal end coupled with the rotatable
body, and extends between the distal and proximal ends. In this working
machine, the rotatable body is adapted to be switchably moved in turn from
a first rotational position for stopping the engine, through a second
rotational position for allowing the engine to be started, to a third
rotational position for activating the choke open/close mechanism.
Further, the rotatable body is formed with an elongated slot which
receives therein the proximal end such that when the rotatable body is
rotated from the first rotational position to the second rotational
position, the proximal end is allowed to displace relative to and in the
radial direction of the rotatable body along the elongated slot so as to
cause a swing movement of the choke-activating link member about the
distal end. When the rotatable body is rotated from the second rotational
position to the third rotational position, the proximal end is restricted
in its displacement along the elongated slot so that the choke-activating
link member is moved in the longitudinal direction in response to the
movement of the rotatable body to transmit the movement of the rotatable
body to the arm.
In the working machine according to the second aspect of the present
invention, when the rotatable body is rotated from the first rotational
position to the second rotational position, the proximal end is allowed to
displace relative to the rotatable body along the elongated slot so as to
case only the swing movement of the choke-activating link member about the
distal end. That is, the distal end of the choke-activating link member
has substantially no movement. Thus, the arm attached to the choke shaft
is not swung, and the choke valve is not closed. Further, when the
rotatable body is rotated from the second rotational position to the third
rotational position, the proximal end is restricted in its displacement
along the elongated slot so that the movement of the rotatable body is
transmitted to the choke-activating link member to move the
choke-activating link member in the longitudinal direction so as to
transmit the movement of the rotatable body to the arm.
Further, in order to achieve the above object, according to a third aspect
of the present invention, there is provided a working machine including an
internal combustion engine serving as a power source therefor. The working
machine comprises: a single operation unit for switching between stop,
start and choke operations of the engine, which includes a rotatable body
capable of being rotationally moved according to a manual operation; a
choke open/close mechanism for an intake system of the engine, which
includes a choke valve, a choke shaft for rotating the choke valve, and an
arm attached to the choke shaft; and a choke-activating link member
adapted to be moved in its longitudinal direction to transmit the movement
of the rotatable body to the arm so as to close the choke valve. The
choke-activating link member having a distal end coupled with the arm and
a proximal end coupled with the rotatable body, and extending in the
crosswise direction with respect to the distal and proximal ends
therebetween. In this working machine, the rotatable body is adapted to be
switchably moved in turn from a first rotational position for stopping the
engine, through a second rotational position for allowing the engine to be
started, to a third rotational position for activating the choke
open/close mechanism. Further, the rotatable body is formed with an
elongated slot or escape hole extending in the crosswise direction. The
elongated slot has a leading end zone located on a leading side with
respect to the rotation direction of the rotatable body and a trailing end
zone located on a trailing side with respect to the rotation direction.
The rotatable body is adapted to receive therein the proximal end such
that: when the rotatable body is located at the first rotational position,
the proximal end is located in the leading end zone. When the rotatable
body is rotated from the first rotational position to the second
rotational position, the proximal end is moved from the leading end zone
to the trailing end zone while displacing relative to and in the radial
direction of the rotatable body along the elongated slot to cause a swing
movement of the choke-activating link member about the distal end. When
the rotatable body is rotated from the second rotational position to the
third rotational position, the proximal end is held in the trailing end
zone so that the choke-activating link member is moved in the longitudinal
direction in response to the movement of the rotatable body to transmit
the movement of the rotatable body to the arm.
In one embodiment of the present invention, the working machine further
includes a throttle open/close mechanism for opening and closing a
throttle valve of the intake system, an interlock mechanism for
interlocking the throttle open/close mechanism and the choke open/close
mechanism, and a release mechanism including a release lever for releasing
the interlock mechanism. In this case, the operation unit and the release
lever are disposed at the front end portion of a handle extending in the
lengthwise direction of the working machine. The choke open/close
mechanism, the throttle open/close mechanism and the interlock mechanism
are housed in an interior space of the rear end portion of the handle.
Further, the choke-activating link member is a rod-shaped member extending
from the rotatable body to the arm attached to the choke shaft, in the
lengthwise direction through the internal space of the handle. The release
mechanism includes a rod-shaped throttle-releasing link member having a
proximal end coupled with the release lever and a distal end coupled with
the interlock mechanism, and extends in the longitudinal direction through
the interior space of the handle along the choke-activating link member.
In another embodiment of the present invention, the operation unit further
includes a guide portion for guiding the proximal end of the
choke-activating link member from the leading end zone to the trailing end
zone along the elongated slot when the rotatable body is moved from the
first rotational position to the second rotational position, and for
holding the proximal end of the choke-activating link member in the
trailing end zone when the rotatable body is moved from the second
rotational position to the third rotational position. Further, the
rotatable body has a substantially circular shape. The leading end zone is
located inward in the radial direction and on the leading side of the
rotatable body, and the trailing end zone is located outward in the radial
direction and on the trailing side of the rotatable body. The trailing end
zone is spaced apart from the rotation center of the rotatable body by a
first radial distance, and the elongated slot extends obliquely with
respect to the radial direction from the leading end zone to the trailing
end zone. Furthermore, the guide portion has a flat surface region
extending straight in the radial direction of the rotatable body up to a
position of a second radial distance derived by subtracting the outside
dimension of the proximal end of the choke-activating link member from the
first radial distance, and an arc surface region extending from the
radially outer end of the flat surface region to the leading side of the
rotatable body to form an arc having a radius of the second radial
distance about the rotation center. In this case, when the rotatable body
is located at the first rotational position, the proximal end of the
choke-activating link member is located in the elongated slot on the
trailing side with respect to the flat surface region. When the rotatable
body is moved from the first rotational position to the third rotational
position, the proximal end of the choke-activating link member is moved
along the flat surface and arc surface regions.
Thus, the present invention can provide a working machine capable of
switching an internal combustion engine between stop, start and choke
operations by a single operation unit, with a simplified mechanism for
transmitting operational movements.
Other features and advantages of the present invention will be apparent
from the accompanying drawings and from the detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a right side outer view of a chain saw according to one
embodiment of the present invention;
FIG. 2 is an enlarged left side view of the internal mechanisms in a handle
of the chain saw;
FIG. 3 is an enlarged left side view of the internal mechanisms in the
handle of the chain saw, wherein the operation unit is located at an
engine-start position;
FIG. 4 is an enlarged left side view of the internal mechanisms in the
handle of the chain saw, wherein the operation unit is located at a
choke-activation position; and
FIGS. 5A-5C are explanatory diagrams of the operations of a choke
open/close mechanism, throttle-valve open/close mechanism and an interlock
mechanism therefor.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to the drawings, a working machine according to one
embodiment of the present invention will now be desribed. In this
embodiment, the present invention will be described as a chain saw being
one example of the working machine.
FIG. 1 is a right side outer view of a chain saw, more particularly a top
handle chain saw, according to an embodiment of the present invention. In
this figure, a chain saw bar portion, i.e., working member, is indicated
by the two-dot chain lines.
As shown in FIG. 1, the working machine or the chain saw 2 comprises a main
body 6 having a housing 4, an internal combustion engine E, such as an
air-cooled 2-cycle gasoline engine housed in the house 4, and a chain saw
bar portion 8 extending forward from the main body 6. A handle 10 to be
gripped by an operator's right hand is provided on the upper surface of
the housing 4 of the main body extending in the lengthwise direction of
the working machine. A single operation unit 12 is provided on the upper
surface of the front end portion 10b of the handle 10. The single
operation unit 12 is adapted to switch between stop, start and choke
operations of the internal combustion engine E. The handle 10 is provided
on the upper surface of the housing 4 of the main body to form an
inverted-U shape, so as to provide a gripping portion 10a extending
straight in the lengthwise direction to allow an operator to get a firm
grip there, the front end portion 10b extending vertically at the front
end thereof, and a rear end portion 10c extending vertically at the rear
end thereof.
FIGS. 2 to 4 are enlarged left side views of internal mechanisms located
within the handle of the chain saw, wherein FIG. 2 shows the state when
the operation unit is located at an engine-stop position, FIG. 3 showing
the state when the operation unit is located at an engine-start position,
and FIG. 4 showing the state when the operation unit is located at a
choke-activation position. FIGS. 2 to 4 are illustrated back to front with
respect to FIG. 1, and thereby the left-hand side and right-hand side of
FIGS. 2 to 4 correspond to the front side and rear side of the chain saw
in FIG. 1, respectively. FIGS. 5A-5C show the operations of a choke
open/close mechanism, throttle-valve open/close mechanism and an interlock
mechanism therebetween.
As shown in FIG. 2, the operation unit 12 is disposed in the interior space
of the front end portion 10b of the handle 10. The operation unit 12
includes a rotatable body 14 capable of being rotationally moved according
to manual operation. More specifically, the rotatable body 14 is adapted
to be switchably moved from the near side to the distant side with
respective to the grip portion 10a, or from the rear side to front side of
the chain saw along the longitudinal direction X of the grip portion 10a.
Body 14 moves from a first rotational position (engine-stop position as
shown in FIG. 2) P1 for stopping the engine E, through a second rotational
position (engine-start position as shown in FIG. 3) P2 for allowing the
engine E to be started and to a third rotational position
(choke-activation position as shown in FIG. 4) P3 for activating a choke
open/close mechanism 18. Thus, when an operator pushes a knob 14a of the
rotatable body 14 frontward, for example, by the thumb of the operator's
right hand gripping the grip portion 10a, the upper half portion of the
rotatable body 14 is rotated away the grip portion 10a while the lower
half portion of the rotatable body 14 is rotated to move forward the grip
portion 10a. That is, the rotatable body 14 is rotated counterclockwise in
FIG. 2.
As described in detail herein and with reference to FIGS. 5A-C, the
interior space of the rear end portion of the handle houses the choke
open/close mechanism 18 for opening and closing a choke valve 16 of a
diaphragm-type carburetor 60, the throttle open/close mechanism 22 for
opening and closing a throttle valve of the carburetor, and the interlock
mechanism 24 for interlocking these mechanisms. In order to facilitate
starting of the engine E when it is cold (i.e., during cold start), the
choke open/close mechanism 18 is activated to close the choke valve 16. In
this operation, the interlock mechanism 24 is operable to interlock the
choke open/close mechanism 18 and the throttle open/close mechanism 22 to
partially open the throttle valve so as to provide a slightly higher
engine speed than the idling speed in the engine E.
Referring once again to FIG. 2, the interior space of the grip portion 10a
is provided with a choke activation mechanism 26 for activating the choke
open/close mechanism 18, and a release mechanism 28 for releasing the
interlock mechanism 24.
With reference to FIGS. 5A-C, the choke open/close mechanism will be
described in more detail. The choke open/close mechanism 18 includes the
choke valve 16, a choke shaft 30 for rotating the choke valve 16, and a
choke-activating arm member 32 fixedly attached at the outer end of the
choke shaft 30 to extend in the crosswise (radial) direction of the choke
shaft. The throttle open/close mechanism 22 includes the throttle valve
20, and a throttle shaft 34 for rotating the throttle valve 20.
With reference to FIG. 2, the choke activation mechanism 26 will be
described in more detail. In the interior space of the handle 10, the
choke activation mechanism 26 includes a choke-activating link member 36
adapted to be moved in the longitudinal direction X to transmit the
movement of the rotatable body 14 to the choke-activating arm member 32 so
as to close the choke valve 16. The choke-activating link member 36 has a
distal end 36a coupled with the choke-actuating arm member 32 and a
proximal end 36b coupled with the rotatable body 14, and extends between
the distal and proximal ends. More specifically, the choke-activating link
member 36 is one piece of elongated rod-shaped member (wire rod having
rigidity and circular cross-section) extending from the rotatable body 14
to the choke-actuating arm member 32. The choke-activating link member 36
also has a shape in conformity with the shape of the interior space of the
inverted-U-shaped handle 10. The choke-activating link member 36 includes
a straight portion extending straight along the grip portion 10a of the
handle 10 and a bent portion extending downward toward the
choke-activating arm member 32 of the interlock mechanism 24, to form an L
shape as a whole. In this embodiment, the choke-activating link member 36
is formed by bending an elongated rod-shaped member to have the above
shape.
The rotatable body 14 is formed with an elongated slot 38 receiving the
bent proximal end 36b. When the knob 14a of the rotatable body 14 is
rotated to more across a click stop device 13 from the first position P1
to the second position P2, the proximal end 36b of the choke-activating
link member 36 is allowed to be displaced relative to the rotatable body
14 along the elongated slot 38 so that the choke-activating link member 36
has substantially no movement relative to the main body 4 in the direction
X. More specifically, the escape hole is an elongated slot. The elongated
slot 38 has a leading end zone 38a which is located inward in the radial
direction of the rotatable body 14 and on a leading side with respect to
the counterclockwise rotation direction of the rotatable body 14, and a
trailing end zone 38b which is located outward in the radial direction and
on a trailing side with respect to the rotation direction. The elongated
slot 38 extends obliquely with respect to the radial direction of the
rotatable body 14 from the leading end zone 38a to the trailing end zone
38b. That is, in the side view of the rotatable body 14 shown in FIG. 2,
the elongated slot 38 is located in the lower region of the circular
rotatable body 14 and in the quarter region of the rotatable body on the
trailing side of the counterclockwise rotation direction, and extends
toward the trailing side of the counterclockwise rotation direction in the
longitudinal direction X of the rod-shaped choke-activating link member
36, from the leading end zone 38a located obliquely downward with respect
to the rotation center O of the rotatable body 14 to the trailing end zone
38b. The elongated slot 38 is slightly curved downward to form an arc
shape.
The rotatable body 14 has a substantially circular shape as a whole, and
the trailing end zone 38b is located to protrude radially outward from the
peripheral portion of the circular rotatable body 14. That is, the
rotatable body 14 is formed with a raised portion 50 (FIG. 2) protruding
radially outward, and the elongated slot 38 extends up to the raised
portion 50. On the other hand, the proximal end 36b of the
choke-activating link member 36 is bent at a right angle. The bent portion
is inserted into the elongated slot 38. The trailing end zone 38b of the
elongated slot 38 is formed with a dent zone 38c for receiving therein the
bent portion, on the leading side of the rotatable body 14.
A guide portion 40 is provided adjacent to the elongated slot 38. The guide
portion 40 is adapted to guide the proximal end 36b of the
choke-activating link member 36 from the leading end zone 38a to the
trailing end zone 38b along the elongated slot 38 when the rotatable body
14 is moved from the first rotational position P1 to the second rotational
position P2, and to hold the proximal end 36b of the choke-activating link
member 36 at a constant position in the trailing end zone 38b of the
elongated slot 38 when the rotatable body 14 is moved from the second
rotational position P2 to the third rotational position P3. The guide
portion 40 has a flat surface region 40a extending radially straight from
the rotation center O of the circular rotatable body 14 up to the
peripheral portion of the rotatable body 14, and an arc surface region 40b
extending from the radially outer end of the flat surface region 40a to
the leading side of the rotatable body 14 to form an arc having a second
radial distance r2 inside the peripheral portion about the rotation
center. Thus, the guide portion 40 has a substantially L-shaped surface.
More specifically, the trailing end zone 38b is spaced apart from the
rotation center O of the rotatable body 14 by a first radial distance r1.
Further, in the guide portion 40, the flat surface region 40a extends
straight in the radial direction of the rotatable body 14 up to a position
of the second radial distance derived by subtracting the outside dimension
of the bent proximal end 36b of the choke-activating link member 36 from
the first radial distance, and the arc surface region 40b extends from the
radially outer end of the flat surface region 40a to the leading side of
the rotatable body 14 to form an arc having the radius r2 of the second
radial distance about the rotation center O of the rotatable body 14.
The guide portion 40 is formed to protrude from the inner surface of the
housing 4 in the front end region 10b of the handle 10. In the first
rotational position P1, the proximal end 36b of the choke-activating link
member 36 is located in the elongated slot 38 on the trailing side of the
counterclockwise rotation direction with respect to the flat surface
region 40a. When the rotatable body 14 is moved from the second rotational
position P2 to the third rotational position P3, the proximal end 36b of
the choke-activating link member 36 is moved along the flat surface region
40a and arc surface region 40b.
The interlock mechanism 24 will now be described with reference to FIGS.
5A-5C. The interlock mechanism 24 has a similar structure to that of
auto-return choke devices of conventional carburetors, and thereby it will
be described briefly. As can be seen from FIGS. 5A-5C, the choke-actuating
arm member 32 is disposed adjacent to an after-mentioned
throttle-releasing arm member 44. The interlock mechanism 24 comprises an
engagement pawl 42a formed at the top of the rotation member 42 rotated
integrally with the choke-activating arm member 32 attached at the outer
end of the choke shaft, and another engagement pawl 44a formed at the top
of the throttle-releasing arm member 44. These engagement pawls 42a, 44a
are engaged with and disengaged from one another in response to the
respective rotations of the choke shaft 30 and the throttle shaft 34 to
act as the interlock mechanism 24.
The release mechanism 28 used for releasing the interlock mechanism 24 for
interlocking the choke-valve open/close mechanism 18 and the
throttle-valve open/close mechanism 22 will be described below. This
release mechanism 28 is also similar to a conventional trigger-type
throttle control device, and thereby it will be described briefly. The
release mechanism 28 includes a sector-shaped trigger member 46 disposed
on the lower surface side of the front end region of the grip 10a and
swingably attached to the main body, the throttle-releasing arm member 44
attached to the throttle shaft 34, and a rod-shaped throttle-releasing
link member 48 having a bent proximal end 48b attached to the trigger
member 46 and a bent distal end 48a attached to the throttle-releasing arm
member 44. The throttle-releasing link member 48 is one piece of elongated
circular-sectional wire rod member extending from the trigger member 46 to
the throttle-releasing link member 48, and has a shape in conformity with
the interior space of the inversed-U-shaped handle 10. The
throttle-releasing link member 48 includes a straight portion extending
straight along the grip portion 10a of the handle 10, and a bend portion
extending downward toward the throttle-releasing arm member 44 of the
interlock mechanism 24, to form an L shape as a whole.
A safety hold lever 51 is provided on the upper surface of the front end
region of the grip portion 10a. The safety hold lever 51 prevents the
interlock mechanism 24 from being released by an unintentional operation
of the trigger 46. The trigger member 46 can be pulled only if the safety
hold lever 51 is being pushed while firmly gripping the grip portion 10a.
The choke-activating link member 36 and the throttle-releasing link member
48 are disposed in parallel with one another in the interior space of the
handle 10 without any interference therebetween.
As already described, the trailing end zone 38b of the elongated slot 38 is
formed as the raised portion 50 protruding radially outward from the
peripheral portion of the substantially circular rotatable body 14, as
shown in FIG. 2. A movable switch terminal 52 is disposed adjacent to the
raised portion 50. At a pushed position where the movable switch terminal
52 is pushed by the raised portion 50 (see FIG. 2), the movable switch
terminal 52 is pressed onto a fixed switch terminal 53 protrudingly
provided on the inner surface of the front end region 10b of the handle 10
to disenable the igniting function of the ignition unit. On the other
hand, at a released position where the raised portion 50 is offset (see
FIGS. 3 and 4), the igniting function of the ignition unit is enabled to
allow the engine E to be started.
With reference to FIGS. 2 to 5C, the operations of the choke-valve
open/close mechanism 18, the throttle-valve open/close mechanism 22, the
interlock mechanism 24, the choke activation mechanism 26 and the release
mechanism 28 will be described below.
As shown in FIG. 2, at an initial position, the operation unit 12 is
located at the engine-stop position, and the rotatable body 14 is located
at the first rotational position P1. In this state, the proximal end 36b
of the choke-activating link member 36 is located at the leading end zone
38a of the elongated slot 38. On the other hand, as shown in FIG. 5A, the
choke valve 16 of the choke open/close mechanism 18 is opened, the
throttle valve 20 of the throttle open/close mechanism 22 being at an
opening for an idling speed, and the interlock mechanism 24 is released.
Further, as shown in FIG. 2, the movable switch terminal 52 is pushed by
the raised portion 50 of the rotatable body 14, and thereby is brought
into contact with the fixed switch terminal 53 to disenable the igniting
function of the ignition unit.
Then, as shown in FIG. 3, when the operation unit 12 is moved to the
engine-start position, the rotatable body 14 is rotated counterclockwise
to pass over the click-stop device 13 from the first rotational position
P1 to the second rotational position P2. When the rotatable body 14 is
moved from the first rotational position P1 to the second rotational
position P2, the elongated slot 38 is moved relative to the guide portion
40 toward the leading side while allowing the flat surface region 40a of
the guide portion 40 to move across the elongated slot 38. The proximal
end 36b of the choke-activating link member 36 is guided by the guide 40
to displace toward the trailing side up to the trailing end zone 38b along
the elongated slot 38. When the rotatable body 14 is moved from the first
rotational position P1 to the second rotational position P2, the proximal
end 36b is allowed to displace along the escape hole (elongated slot) 38
to displace relative to and in the radial direction of the rotatable body
14 so as to cause only a small amount of swing movement of the
choke-activating link member 36 about the distal end 36a thereof. That is,
the distal end 36a has substantially no movement in the longitudinal
direction. Thus, the choke open/close mechanism 18 is not activated, and
maintained in the opened position as shown in FIG. 5A to allow the engine
to be started.
Then, as shown in FIG. 4, when the operation unit 12 is moved to the
choke-activation position under the condition of extremely low ambient
temperature, the rotatable body 14 is rotated counterclockwise from the
second rotational position P2 to the third rotational position P3. When
the rotatable body 14 is moved from the second rotational position P2 to
the third rotational position P3, the proximal end 36b of the
choke-activating link member 36 is moved along the arc surface region 40a
of the guide portion 40 while maintaining its position in the trailing end
zone 38b of the elongated slot 38 located on the radial outside of the arc
surface region 40b of the guide portion 40, so as to transmit the movement
of the rotatable body 14 to the choke-activating arm member 32. Thus, as
shown in FIG. 5A, the choke-activating arm member 32 is pushed to rotate
the choke shaft 30 and consequently close the choke valve 16.
Simultaneously, as shown in FIG. 5B, the engagement pawl 42a at the top of
the rotation member 42 and the engagement pawl 44a at the top of the
throttle-releasing arm member 44 are engaged with one another according to
the rotation of the choke shaft 30. Thus, the throttle shaft 34 is rotated
according to the rotation of the choke shaft 30 to partially open the
throttle valve 20 (at an opening for increasing the idling speed) and
maintained at this opening. Then, the engine E will be started by a recoil
starter (not shown) provided in the main body 6.
Upon hearing an initial detonation sound, the operator returns the
operation unit 12 from the choke-activation position (P3) to the
engine-start position (P2). Through this operation, as shown in FIG. 5C,
the choke-activating arm member 32 is pulled frontward by the
choke-activating link member 36, and thereby swung to open the choke valve
16. In this state, the throttle valve 20 is maintained at the partial
opening.
Then, by pulling the trigger member 46 while pushing the safety hold lever
51, the throttle-releasing link member 48 is moved frontward in the
longitudinal direction X in response to the swing movement of the trigger
member 46. Thus, the throttle-releasing arm member 44 is pulled and swung
in response to the movement of the throttle-releasing link member 48 to
release the engagement between the two engagement pawls 42a, 44a of the
interlock mechanism 24, and thereby the throttle valve 20 is return to the
opening position for the idling speed.
According to this embodiment, the stop, start and choke operations can be
performed only by the single operation unit 12. In addition, the choke
operation can be performed by the choke-actuating link member 36 comprised
of a single rod-shaped member extending from the front end region 10b to
the rear end region of the handle 10. This makes it possible to provide
the chain saw 2 with a simplified structure, reduced number of components,
enhanced workability during its assembly process and reduced cost.
Further, this embodiment allows the choke-activating link member 36 to be
reliably guided along the elongated slot 38 by the guide portion 40. This
can achieve reliable operation of the choke open/close mechanism 18.
Furthermore, in this embodiment, the choke-activation link member 36 is
comprised of a rod-shaped member disposed in parallel with the
throttle-activating link member 48. Thus, the choke-activation link member
36 does not interference with the throttle release mechanism, and thereby
any need for design change of existing throttle control mechanisms will be
eliminated.
The present invention is not limited to the above embodiment, and it will
be evident that various modifications and changes may be made to the
embodiment without departing from the spirit and scope of the present
invention as set forth in the claims attached hereto. Accordingly, it is
intended that all such modifications are to be encompassed by the present
invention.
For example, in the above embodiment, based on the longitudinal direction X
of the grip portion extending in the lengthwise direction of the working
machine, the e
