Title: Torque measuring apparatus for rotating body
Abstract: A torque measuring apparatus includes a rotor having a hollow body portion formed between a drive-side flange portion and a load-side flange portion. Light emitting elements are disposed on a periphery of the rotor, for emitting optical signals based on an output from a torque detection unit attached to a hollow portion of the hollow body portion. A transparent plate attached to a chassis is disposed outside the rotor, for allowing the optical signals to pass therethrough, and a signal receiving unit is arranged on the chassis, for receiving the optical signals via the transparent plate, wherein the transparent plate is detachable from the chassis.
Patent Number: 6,907,794 Issued on 06/21/2005 to Arai
| Inventors:
|
Arai; Tooru (Kanagawa-ken, JP)
|
| Assignee:
|
Minebea Co., Ltd. (Nagano-ken, JP)
|
| Appl. No.:
|
805950 |
| Filed:
|
March 22, 2004 |
Foreign Application Priority Data
| Mar 28, 2003[JP] | 2003-091400 |
| Current U.S. Class: |
73/862.324; 73/862 |
| Intern'l Class: |
G01L 003/02 |
| Field of Search: |
73/862,862324-862326
|
References Cited [Referenced By]
U.S. Patent Documents
| 4459759 | Jul., 1984 | Hulsing, II.
| |
| 4992826 | Feb., 1991 | Nakabayashi.
| |
| 5369322 | Nov., 1994 | Maruyama et al.
| |
| 5369583 | Nov., 1994 | Hazelden.
| |
| 5632546 | May., 1997 | Lee.
| |
| 6504275 | Jan., 2003 | Nondahl et al.
| |
| Foreign Patent Documents |
| 1 170 577 | Jan., 2002 | EP.
| |
| 2002/-022566 | Jan., 2002 | JP.
| |
Other References
Patent Abstracts of Japan, vol. 0110, No. 87 (P-557), Mar. 17, 1987 & JP 61 240219
A (Hitachi Ltd.), Oct. 25, 1986.
|
Primary Examiner: Noori; Max
Assistant Examiner: Ellington; Alandra
Attorney, Agent or Firm: Fay, Sharpe, Fagan, Minnich & McKee, LLP
Claims
1. A torque measuring apparatus comprising:
a rotor having a hollow body portion formed between a drive-side flange portion
and a load-side flange portion;
light emitting elements disposed on a periphery of the rotor, for emitting optical
signals based on an output from a torque detection unit arranged on a hollow portion
of the hollow body portion;
a transparent plate attached to a chassis disposed outside the rotor, for allowing
the optical signals to pass therethrough;
a signal receiving unit attached to the chassis, for receiving the optical signals
via the transparent plate, wherein the transparent plate is detachable from the
chassis; and
a slide mechanism for sliding the transparent plate.
2. The torque measuring apparatus according to claim 1, wherein the slide mechanism
comprises a manually operated element.
3. The torque measuring apparatus according to claim 1, wherein the slide mechanism
comprises a motor for sliding the transparent plate by operation of an operating switch.
4. The torque measuring apparatus according to claim 3, wherein the transparent
plate is caused to slide by means of the motor driven slide mechanism when contamination
is detected on the transparent plate.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a torque measuring apparatus for which cleaning
operations can easily be performed for removing oil mist or the like attached onto
signal receiving units adapted to receive optical signals from a rotor.
2. Description of the Related Art
A torque measuring apparatus is arranged between a rotating shaft at a drive
end
and a rotating shaft at a load end to measure rotational torque without contact
with these shafts. In one application, the torque measuring apparatus is used to
measure rotational torque between a measuring roller and a brake mechanism in a
chassis dynamo adopted to be rotated by the wheel of an automobile (see, e.g.,
Japanese Patent Application Laid-Open No. 2002-22566).
FIG. 1 is a front view of a conventional torque measuring apparatus, while FIG.
2 is a partial cross sectional side view of the conventional torque measuring apparatus.
As shown in FIGS. 1 and 2, a conventional torque measuring apparatus
50
is constructed from a rotor
51 arranged between a drive-side shaft
91
and a load-side shaft
93, and a fixed body
55 fixed to the outside
of the rotor
51, and is attached between the drive-side shaft
91
and the load-side shaft
93. The rotor
51 is integrated with a drive-side
flange portion
52 attached to a flange
92 of the drive-side shaft
91, a load-side flange portion
54 attached to the flange
94
of the load-side shaft
93, and a hollow body portion
53 between the
drive-side flange portion
52 and the load-side flange portion
54,
and the fixed body
55 is constructed from an annular portion
56 provided
on the outside of the load-side flange portion
54 and a chassis
57
to which the annular portion
56 is fixed via a fixture portion
58.
A primary coil
87 is provided in the annular portion
56 arranged
on the outside of the load-side flange portion
54, and a secondary coil
88 is provided around the outer periphery of the load-side flange portion
54, the primary coil
87 and secondary coil
88 forming a rotary
transformer
89 to supply power to the rotor
51.
In a hollow portion
59 of the hollow body portion
53, a strain
gauge
torque detection unit
61 is provided, a plurality of light emitting elements
67a to
67n for emitting light or optical signals based
on the output from a torque detection unit
61 are provided around the outer
periphery of the load-side flange portion
54, an optical fiber
31
for receiving the optical signals from the light emitting elements
67a
to
67n is arranged alongside the primary coil
87 in the
annular portion
56, and at the end portion of the optical fiber
71
an optical signal conversion unit (not shown) for conversion to electrical signals
is provided.
Consequently, the torque measuring apparatus
50, when the drive-side
shaft
91 rotates and drives, detects the output from the torque detection
unit
61 via the light emitting elements
67a to
67n
and the optical fiber
31, by means of the optical signal conversion
unit, whereby the rotational torque is detected.
As described above, although the conventional torque measuring apparatus
50
is interposed between the drive-side shaft
91 and the load-side shaft
93
and can measure torque without being in contact with its rotating portion, the
torque measuring apparatus are installed in many cases in the environment in which
oil mist or the like is generated.
As a result, the oil mist or the like attached onto the light receiving fiber
71 as a light receiving portion may cause damage to measuring precision
and abnormal conditions such as impossibility of measurement, so that the light
receiving fiber
71 must be cleaned. However, the cleaning operation is rather
difficult because the light receiving optical fiber
31 is arranged inside
the annular portion
56, leading to a demand for improvement in the cleaning operation.
SUMMARY OF THE INVENTION
The present invention was conceived in light of the above problem of the prior
art, and it is therefore an object of the present invention to provide a torque
measuring apparatus for which cleaning operations on the light receiving portions
for receiving optical signals from the rotor is easy.
In order to attain the above object, according to a major aspect of the present
invention there is provided a torque measuring apparatus comprising a rotor having
a hollow body portion formed between a drive-side flange portion and a load-side
flange portion; light emitting elements disposed on a periphery of the rotor, for
emitting optical signals based on an output from a torque detection unit attached
to a hollow portion of the hollow body portion; a transparent plate attached to
a chassis disposed outside the rotor, for allowing the optical signals to pass
therethrough; and a signal receiving unit arranged on the chassis, for receiving
the optical signals via the transparent plate, wherein the transparent plate is
detachable from the chassis.
Preferably, the torque measuring apparatus of the present invention may
comprise a slide mechanism for sliding the transparent plate by manual operation.
The torque measuring apparatus may further comprise a motor driven slide mechanism
for sliding the transparent plate by operation of an operating switch. When abnormal
contamination is detected on the transparent plate, the transparent plate may be
slidable by means of the motor driven slide mechanism.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects, features, aspects and advantages of the present invention
will become better understood with reference to the following description, appended
claims and accompanying drawings, in which:
FIG. 1 is a front view of a conventional measuring apparatus;
FIG. 2 is a partial cross sectional side view of the conventional torque measuring apparatus;
FIG. 3 is a front view of a torque measuring apparatus according to an embodiment
of the present invention;
FIG. 4 is a partially cut-away side view of the torque measuring apparatus according
to the embodiment of the present invention;
FIG. 5 is an exploded perspective view showing a transparent plate being attached
to a chassis by means of a protective cover; and
FIG. 6A is an exploded perspective view showing a transparent plate being attached
to a chassis by means of a protective cover and being slidable by means of a sliding
mechanism, and
FIG. 6B is a cross sectional view of the sliding mechanism.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiments of the present invention will be described hereinbelow.
FIG. 3 is a front view of a torque measuring apparatus according to an embodiment
of the present invention, and FIG. 4 is a partially cut-away side view of the torque
measuring apparatus shown in FIG.
3.
As shown in FIGS. 3 and 4, a torque measuring apparatus
10 of the embodiment
of the present invention is composed of a rotor
11 arranged between a drive-side
shaft
91 and a load-side shaft
93, and a fixed body
15 fixed
to the outside of the rotor
11, and is disposed between the drive-side shaft
91 and the load-side shaft
93. The rotor
11 is integrated
with a drive-side flange portion
12 attached to a flange
92 of the
drive-side shaft
91, a load-side flange portion
14 attached to a
flange
94 of the load-side shaft
93, and a hollow body portion
13
between the drive-side flange portion
12 and the load-side flange portion
14. The fixed body
15 is constructed from a half structured annular
portion
16 provided on the outside of the load-side flange portion
14
and a chassis
17 to which the half structured annular portion
16
is fixed.
The drive-side flange portion
12 is fixed to the flange
92 by a
screw (not shown) passing through a threaded hole
12a in the drive-side
flange portion
12 and an attachment hole
92a in the flange
92. Also, the load-side flange portion
14 is fixed to the flange
94 by a screw (not shown) passing through a threaded hole
14a
in the drive-side flange portion
14 and an attachment hole
94a
in the flange
94. The hollow body portion
13 is twisted by the
drive-side flange portion
12 and the load-side flange portion
14
to form a strain-causing body.
The half structured annular portion
16 has semi-annular portions
16a
and
16b whose upper ends are both connected by a conductive connecting
member
16T, the lower ends of the semi-annular portions
16a and
16b being fixed in an insulated state to fixture members
18a
and
18b mounted on the chassis
17. That is, because the
half structured annular portion
16 is of a discontinuous annular shape notched
at its lower end, and fixed in an insulated state, the half structured annular
portion
16 can serve as a primary coil and can be easily attached or detached.
This primary coil forms a rotary transformer
39 together with a secondary
coil
38 provided on the outer periphery of the load-side flange portion
14, and can supply electric power to the rotor
11.
In a hollow portion
19 of the hollow body portion
13 is provided
a strain gauge torque detection unit
21, and a plurality of light emitting
elements
27a to
27n are provided along the outer periphery
of the load-side flange portion
14 for emitting light in response to the
output of the torque detection unit
21 and transmitting an optical signal
L. In the chassis
17, an optical fiber
31, for receiving optical
signals from the light emitting elements
27a to
27n,
is arranged in a linear shape with both end portions bent into L shapes so that
it can be compactly housed inside the chassis
17. Also, in the chassis
17
on its upper surface is attached a transparent plate
43 that allows the
optical signal to pass through, and the transparent plate
43 serves to prevent
oil mist, dust or the like from entering to the interior of the chassis
17
and protect the light receiving fiber
31. A protective cover
41 for
protecting the transparent plate
43 is attached to the chassis
17,
and the transparent plate
43 is detachably mounted on the protective cover
41.
Facing the end surfaces of the optical fiber
31, optical signal conversion
units
33a and
33b for receiving optical signals via
optical high pass filters
32a and
32b and converting
them to electrical signals are provided. Electrical components of the rotor
11
are mounted on a mounting base plate
28.
FIG. 5 shows the transparent plate being attached to the chassis
17 by
means of the protective cover
41.
As shown in FIG. 5, the protective cover
41 has a light conducting opening
41a for allowing the optical signal L to pass onto its upper surface,
and holes
41b for insertion of the transparent plate
43 opened
on its left and right side surfaces. The protective cover
41 is fixed to
the chassis
17 by threading screws
42 through holes
41c
into threaded holes
41d. A channel
44 is formed in the
chassis
17 and the transparent plate
43 can be inserted from the
insertion holes
41b into the protective cover
41 attached
to the chassis
17. The transparent plate
43 is slid and detached
as indicated by an arrow S so that the oil mist or the like attached on the transparent
plate
43 can be cleaned off. A light conducting hole
45 is provided
in the chassis
17, and the optical signal L passing through the light conducting
opening
41a passes through the transparent plate
43 and the
light conducting hole
45, and is incident on the optical fiber
31
arranged inside the chassis
17 as shown in FIG.
3.
FIG. 6A is an exploded perspective view showing a sliding mechanism provided
in the chassis and FIG. 6B is a cross sectional view of the sliding mechanism.
As shown in FIG. 6B, a sliding mechanism
40 is arranged inside the chassis
17. The sliding mechanism
40 has an operating knob
47 and
a roller
48 attached to a shaft
49, which is rotated by the operating
knob
47, when the transparent plate
43 is inserted through the insertion
hole
41b into the channel
44, comes into contact with the
roller
48. The transparent plate
43 can be slid in the channel
44
and detached as indicated by the arrow S by rotating the operating knob
47
so that the oil mist or the like which is on the transparent plate
43 can
be cleaned off. The optical signal L passing through the light conducting hole
41a passes through the transparent plate
43 and the light
conducting hole
45, and is incident on the optical fiber
31 arranged
inside the chassis
17.
The slide mechanism
40 can be driven by a motor (not shown) to rotate
the shaft
49 so that the transparent plate
43 can be slid and detached
to clean off the oil mist or the like thereon.
Contaminants on the transparent plate
43 can be detected in terms
of a level of the optical signal passing through the transparent plate
43,
and the oil mist or the like on the transparent plate
43 can automatically
be cleaned off by sliding the transparent plate
43 by means of the motor
provided in the slide mechanism
40 on the basis of the contaminant level
thus detected.
Further, a thin film may be applied to the surface of the transparent plate
43 and by peeling off this film, the oil mist or the like on the transparent
plate
43 can be cleaned off.
Next, the operation of the torque measuring apparatus according to the embodiment
of the present invention will be described.
As shown in FIG. 4, strain gauges are affixed on the hollow portion
19
of the hollow body portion
13 of the strain-causing body along the circumferential
direction, and the strain gauges constitute a part of a Wheatstone bridge to form
the torque detection unit
21. An analog output from the torque detection
unit
21 is converted to the optical signal L by the light emitting elements
27a to
27n which in turn is transmitted.
In the fixed body
15, the optical signal L from the light emitting elements
27a to
27n via the transparent plate
43 is received
by the optical fiber
31 after being diffused by a diffusion plate
34,
and the received optical signal L transmits in the optical fiber
31 in the
left and right directions. The optical high pass filters
32a and
32b remove incidental light caused by fluorescent lamps or the like,
and torque detection is performed by converting the optical signal to a torque
signal which is an electrical signal by means of the optical signal conversion
units
33a and
33b. The transparent plate
43
is slidable and detachable, and therefore the oil mist or the like attached to
the transparent plate
43 can be cleaned off by taking out the transparent
plate
43.
In the fixed body
15, an electric power of a given frequency is generated
and is transmitted to the rotor side via the rotary transformer
39. Then
the electric power is converted to direct current and supplied to the rotor
11.
As described above, according to the torque measuring apparatus
10 of
the
first embodiment of the present invention, when the drive-side shaft
91
is driven, the output from the torque detection unit
21 is converted to
the optical signal L by the light emitting elements
27a to
27n
which is transmitted whereby measurement of the rotational torque is performed.
The optical fiber
31 that receives the optical signal L is installed inside
the chassis
17, and the transparent plate
43 is detachably installed
on the optical signal receiving side of the chassis
17 whereby the oil mist
or the like on the transparent palate
43 can be easily cleaned off.
Although the torque measuring apparatus of the embodiment of the present
invention has been explained in a case where the single optical fiber
31
is used, more than one optical fibers may be used in combination with one or more
optical signal conversion units at both ends of these fibers to receive optical signals.
In the torque measuring apparatus according to this embodiment of the present
invention, the number of light emitting elements
27a to
27n
is set so that the optical fiber
31 can continuously receive optical
signals from any one of the plurality of light emitting elements
27a
to
27n, rotational torque can be measured even when the shafts
of the driven-side flange portion
12 and the load-side flange portion
14
are stopped or rotating at a low speed.
A torque measuring apparatus of the present invention comprises a rotor having
a hollow body portion formed between a drive-side flange portion and a load-side
flange portion; light emitting elements disposed on a periphery of the rotor for
emitting optical signals based on an output from a torque detection unit arranged
on a hollow portion of the hollow body portion; a transparent plate attached to
a chassis disposed outside the rotor for allowing the optical signals to pass therethrough;
and a signal receiving unit attached to the chassis for receiving the optical signals
via the transparent plate, the transparent plate being detachable from the chassis.
Removal and cleaning of oil mist or the like attached to the transparent plate
can be easily performed and the cleaning operation for light receiving portions
can be easily performed.
The torque measuring apparatus may have the slide mechanism for sliding the transparent
plate by manual operation and therefore, the transparent plate can be easily detached
so that oil mist or the like attached to the transparent plate can be easily cleaned off.
Further, the torque measuring apparatus may have a motor driven slide mechanism
that slides the transparent plate by the operation of an operating switch, and
therefore the transparent plate can be simply detached so that oil mist or the
like attached to the transparent plate can be easily cleaned off.
Furthermore, the transparent plate may be slid by the motor driven slide
mechanism when undesired contamination is detected on the transparent plate, and
therefore oil mist and the like attached to the transparent plate can be cleaned
off at an appropriate time.
While preferred embodiment of the present invention has been described in detail
for illustrative purpose herein, it is to be understood that the inventive concepts
may be otherwise variously embodied and employed and that the appended claims are
intended to be construed to include such variations except insofar as limited by
the prior art.
*
