Title: Filter device
Abstract: A filter device having a filter element arranged in a filter housing that can be sealed by a housing lid with a sealing ring. The medium to be filtered is supplied to the filter element through an inlet opening in the filter housing. On the filtered side of the filter element, the filtered medium is discharged through an outlet opening in the filter housing. The housing lid is constructed in two parts and includes an inner lid and an outer lid. The inner lid can be inserted into a housing opening, with the sealing ring arranged between the inner lid and the wall of the housing opening. The outer lid covers the housing opening and is connected with the wall of the housing opening by a locking mechanism.
Patent Number: 6,918,939 Issued on 07/19/2005 to Dworatzek, et al.
| Inventors:
|
Dworatzek; Klemens (Edingen, DE);
Muenkel; Karlheinz (Oberderdingen-Flehingen, DE);
Hartmann; Marion (Hockenheim, DE)
|
| Assignee:
|
Mann & Hummel GmbH (Ludwigsburg, DE)
|
| Appl. No.:
|
619554 |
| Filed:
|
July 16, 2003 |
Foreign Application Priority Data
| Jul 16, 2002[DE] | 102 32 046 |
| Current U.S. Class: |
55/313; 55/385.3; 55/DIG.28; 210/450 |
| Intern'l Class: |
B01D 035/30 |
| Field of Search: |
55/310,312,313,314,385.3,DIG.28
210/450
|
References Cited [Referenced By]
U.S. Patent Documents
| 5429101 | Jul., 1995 | Uebelhoer et al.
| |
| 5450835 | Sep., 1995 | Wagner.
| |
| 5601710 | Feb., 1997 | Yoon et al.
| |
| 6723149 | Apr., 2004 | Ernst et al.
| |
| Foreign Patent Documents |
| 19647256 | May., 1998 | DE.
| |
| WO 01/9054/0 | Nov., 2001 | WO.
| |
Other References
Copy of German Search Report.
|
Primary Examiner: Hopkins; Robert A.
Attorney, Agent or Firm: Crowell & Moring LLP
Claims
1. A filter device comprising a filter element arranged in a filter housing that
can be sealed by a housing lid with a sealing ring, wherein a medium to be filtered
is supplied to the filter element through an inlet opening in the filter housing,
and filtered medium is discharged on the filtered side of the filter element through
an outlet opening in the filter housing; the housing lid is divided into two parts
and comprises an inner lid and an outer lid; the inner lid can be inserted into
a housing opening with the sealing ring arranged between the inner lid and a wall
of the housing opening, and the outer lid covers the housing opening and is secured
to a wall of the housing opening in a locked position by a locking mechanism.
2. A filter device according to claim 1, wherein the locking mechanism comprises
a locking thread.
3. A filter device according to claim 2, wherein the locking thread has sections
of different thread pitch.
4. A filter device according to claim 3, wherein the locking thread on the housing
opening has a section of a smaller pitch in the area adjacent to the locked position
of the outer lid.
5. A filter device according to claim 1, wherein the inner lid is secured to
the outer lid by an attachment mechanism arranged between the inner lid and the
outer lid.
6. A filter device according to claim 5, wherein the attachment mechanism comprises
at least one attachment projection that engages an attachment groove in a positively
locking manner.
7. A filter device according to claim 1, wherein the inner lid carries the sealing ring.
8. A filter device according to claim 7, wherein the sealing ring is disposed
in a circumferential sealing groove on the outside of the inner lid.
9. A filter device according to claim 1, wherein a pressure relief valve subject
to the pressure on the intake side of the filter element is integrated into the
inner lid.
10. A filter device according to claim 1, wherein a discharge path is formed
between the inner lid and the outer lid.
11. A filter device according to claim 1, wherein said filter device is a crankcase
ventilation filter.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a filter device comprising a filter element
arranged in a filter housing that can be sealed by a housing lid with a sealing
ring, wherein a medium to be filtered is supplied to the filter element through
an inlet opening in the filter housing, and filtered medium is discharged on the
filtered side of the filter element through an outlet opening in the filter housing.
The filter device of the present invention is particularly suitable for use as
a crankcase ventilation filter.
Filter devices for crankcase ventilation, which are also referred to as oil
separators, are used to filter and purify oil-containing air from the crankcase.
The separated oil is returned to the oil circuit, and the cleaned air is normally
introduced into the intake tract of the internal combustion engine. The filter
device comprises a filter element in a filter housing, to which the oil-containing
air is supplied through an inlet opening. The purified air is removed through an
outlet opening in the filter housing. For safety reasons, a pressure relief valve
is integrated into the housing lid. This pressure relief valve is under the pressure
of the inlet side or the unfiltered side of the filter element, and when an overpressure
limit is exceeded it moves to the open position to relieve the pressure in the
filter housing.
Such filter devices are normally cylindrical in shape. The pressure relief valve
is usually located in a housing lid that is placed on an axial end face of the
filter housing. The pressure relief valve is fixed to the housing lid and is held
in the closed position by a valve spring. As soon as the pressure in the filter
housing exceeds a value that causes the pressure relief valve to open against the
force of the valve spring, the oil-containing air flows through the valve out of
the filter housing.
The housing lid is disposed on or in an axial housing opening on the end face
of the filter housing and is sealed by a circumferential sealing ring located between
the inside of the wall of the housing opening and the outside of the housing lid.
The housing lid is normally screwed into the housing opening. For this purpose,
a thread is provided between the wall of the housing opening and the housing lid.
When the housing lid has to be removed, e.g., for maintenance purposes, there
is a risk that the rotational motion that is required to open the housing lid may
damage the sealing ring. Especially if the sealing ring has remained installed
for a prolonged period of time between the wall of the housing opening and the
housing lid, it may be tightly stuck between the two components. As a result, a
relative rotational motion between the filter housing and the housing lid can lead
to strong forces acting on the sealing ring in circumferential direction, which
can damage the sealing ring. The adhesion of the sealing ring also requires substantially
more force to open the housing lid.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide an improved filter device
suitable for use as a crankcase ventilation filter.
Another object of the invention is to provide a filter device which has a
simple design with a filter housing and a removable housing lid.
A further object of the invention is to provide a filter device with a filter
housing
having a closeable lid which reliably seals the housing interior in a pressure
tight manner when closed.
It is also an object of the invention to provide a filter device having a housing
with a lid having a sealing ring in which forces acting on the sealing ring when
the housing lid is opened and closed are minimized.
These and other objects are achieved in accordance with the present invention
by providing a filter device comprising a filter element arranged in a filter housing
that can be sealed by a housing lid with a sealing ring, wherein a medium to be
filtered is supplied to the filter element through an inlet opening in the filter
housing, and filtered medium is discharged through an outlet opening in the filter
housing on the filtered side of the filter element; the housing lid is divided
into two parts and comprises an inner lid and an outer lid; the inner lid can be
inserted into a housing opening with the sealing ring arranged between the inner
lid and a wall of the housing opening, and the outer lid covers the housing opening
and is secured to a wall of the housing opening by a locking mechanism.
Advantageous preferred features and embodiments are described in further
detail hereinafter.
According to the invention, the housing cover is constructed in two parts
and comprises an inner lid and an outer lid. This makes it possible to allocate
different functions to the inner lid and the outer lid. The inner lid is sealed
by the sealing ring in a pressure-tight manner relative to the wall of the housing
opening. The outer lid assumes a closing and retaining function. For this purpose
it is provided with a locking mechanism between the outer lid and the wall of the
housing opening. Thus the inner lid has a sealing function, while the outer lid
has a retaining function and transmits the forces in longitudinal direction.
To mount the housing lid, the inner lid including the sealing ring is first inserted
into the housing opening, for which different motions with axial, rotational or
axial/rotational components come into consideration. After the inner lid has been
inserted, the outer lid can be mounted, and the locking mechanism, which serves
to connect the outer lid to the wall of the housing opening so as to transmit axial
forces, can be closed.
The closing motion of the outer lid, due to its separate configuration, can be
distinct from the closing or insertion motion of the inner lid. For example, it
is possible to use a rotational motion to close and open the outer lid, in which
case the locking mechanism is configured as a locking thread, which is advantageously
formed on the outside of the housing wall and on the inside of the outer lid.
The locking thread can have sections with different thread pitch. In particular,
the section adjacent to the locked position can have a smaller pitch than the section
of the locking thread through which the outer lid passes at the beginning of the
mounting and closing motion. This configuration has the advantage that when the
outer lid is closed, it has to travel a relatively large axial closing path because
of the greater thread pitch, but as it gets closer to the closed position it travels
through a smaller axial path because of the smaller thread pitch, which makes it
easier to control the force or makes it possible to use the force better.
Allowing a relative rotational motion between the outer lid and the inner
lid has the effect of moving the inner lid translationally if the seal sticks when
the lid is being removed. As a result, much less force is required to remove the
lid, and the sealing ring can be removed from the interior of the housing wall
without destroying it.
In one advantageous preferred embodiment, the inner lid is secured to the filter
housing by an attachment mechanism. This attachment mechanism is advantageously
located between the inner lid and the outer lid, so that the inner lid is not directly
connected to the wall of the filter housing. Rather, the latching position is reached
only when the outer lid is mounted and an axial clamping force is applied via the
outer lid, so that axial forces acting on the inner lid are first applied to the
outer lid and through the outer lid are introduced into the wall of the housing
opening and into the filter housing.
The pressure relief valve is advantageously integrated into the inner lid. Between
the inner lid and the outer lid, a discharge path is formed through which the medium
can escape from the interior of the filter housing when the pressure relief valve
is open. The discharge path between the inner lid and the outer lid reduces the
pressure pulse of the medium to be discharged. The discharge path can be configured,
in particular, as an approximately plate-shaped outlet space, which essentially
extends across the axial surface of the inner lid and outer lid. A discharge into
the environment can occur via axial flow paths, which are formed in an overlapping
circumferential section between the outer lid and the inner lid. In this configuration
the outer lid covers the pressure relief valve to protect it from dirt and mechanical damage.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in further detail hereinafter with reference
to illustrative preferred embodiments shown in the accompanying drawing figures,
in which:
FIG. 1 is a perspective view of a filter device having a housing lid in which
a pressure relief valve is disposed;
FIG. 2 is a longitudinal section of the filter device of FIG. 1;
FIG. 3 is a schematic view of a two-part housing lid for a filter device according
to the invention;
FIG. 4 shows mechanical details of the two-part housing lid of FIG. 3;
FIG. 5 is a schematic view of a pressure relief valve in which the valve body,
with the valve in the closed position, is subject to a clamping force of a clamping
mechanism acting perpendicularly to the displacement direction of the valve body, and
FIG. 6 shows a modified pressure relief valve embodiment with two separately
configured clamping mechanisms which apply a clamping force to the body of the
pressure relief valve in both the closed position and in the open position.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The filter device
1 shown in FIG. 1 has a filter element through which
a medium to be filtered flows and which is located inside an approximately cylindrical
housing
2 that can be sealed by a removable housing lid
3. The medium
to be filtered can be introduced into the interior of the filter device in the
direction indicated by the arrow
5 through an inlet
4 that is disposed
on the side of the filter housing
2. After being filtered, the medium is
discharged in the direction of the arrow
7 through an outlet
6, which
is likewise disposed on the side of the housing. The medium to be filtered can
be a gas or possibly also a liquid.
According to a preferred embodiment, the filter device
1 is configured
as an oil separator in which oil droplets are separated from an oil/air mixture
formed, for example, in the crankcase of an internal combustion engine. The air
discharged from the crankcase is filtered and supplied, in particular, to an inlet
port of the internal combustion engine. However, the filter device can also be
used in a gas filter or a liquid filter.
As can be seen from FIG. 1 in conjunction with FIG. 2, a pressure relief valve
8 is integrated into the housing lid
3 disposed in the area of an
axial end face of the filter housing
2. This pressure relief valve is subject
to the pressure of the inlet side of the filter element. If an allowable pressure
limit is exceeded, this valve moves to the open position, so that the medium introduced
on the unfiltered side can escape the filter housing to prevent overload.
On the filtered side of the filter device, a pressure regulating valve
9
is disposed in the region of the outlet
6. This pressure regulating valve
serves to prevent an excessive negative pressure in the crankcase. There must always
be a relatively low negative pressure here, which varies within a very small pressure
range. If the negative pressure on the side of the intake manifold were very high,
it would propagate counter to the direction of arrow
7 through the normally
open pressure regulating valve
9, counter to the direction of arrow
5
all the way into the crankcase.
The pressure regulating valve
9 is always in the open position when a
relative negative pressure within the desired pressure range with respect to the
outside of the filter device
1 is present on the filtered side. This is
achieved by biasing the pressure regulating valve
9 with a valve spring
23 (See FIG.
5). However, if the relative negative pressure of the
filter device
1 in relation to the outside pressure exceeds the bias of
the valve spring
23 acting against this pressure, the pressure regulating
valve moves to the closed position.
As the sectional view according to FIG. 2 further shows, the medium to be filtered
is introduced into the interior of the filter housing
2 through the inlet
4. The filter housing contains a cylindrical filter element
11 whose
radial interior forms the inlet or unfiltered side, from where the fluid to be
filtered flows radially through the filter element from the inside to the outside.
In the case of a separator, the separated oil droplets drain in downward direction
along the radial inner surface of the filter element
11. The filtered air
passes radially through the filter element from the inside to the outside, is collected
in an annular space that radially encircles the filter element
11 and after
passing through the pressure regulating valve
9 is discharged toward the outside.
A bypass valve
10 is disposed in the bottom region in the interior of
the
filter element
11. If a minimum pressure is exceeded, this bypass valve
moves to the open position, whereupon the separated oil droplets drain in downward
direction through a conically tapering region of the filter housing
2 and
are discharged through a discharge opening
12.
FIGS. 3 and 4 show a modified embodiment of a housing lid
3. The housing
lid
3 is constructed in two parts and comprises an inner lid
13 and
an outer lid
14. The inner lid
13 is inserted into a housing opening
15 of the filter housing
2. A sealing ring
16 is mounted on
the outside of the inner lid
13 and fits against the inner wall of the housing
opening
15 to form a seal.
The outer lid
14 is approximately parallel to the inner lid
13
and covers the housing opening
15, so that the inside of a cylindrical wall
section of the outer lid
14 is adjacent the outside wall of the housing
opening
15. The outer lid
14 is connected to the wall of the housing
opening
15 via a locking mechanism
17.
The inner lid
13 carries the pressure relief valve
8, which in
the open position opens a flow path through the inner lid
13 into a discharge
path
18 formed between the inner lid
13 and the outer lid
14.
This discharge path
18 is formed, in particular, because the inner lid
13
and the outer lid
14 are spaced apart from each other to form an approximately
plate-shaped flow space that essentially extends across the end face of the inner
lid and the outer lid.
It may also be advantageous to provide flow grooves on the outside of the inner
lid
13 and/or on the inside of the outer lid
14 for the excess pressure
that is to be discharged from the interior of the filter housing
2. The
medium flowing into the discharge path
18 when the pressure relief valve
8 is open is guided radially outwardly and leaves the discharge path
18
between the inner lid
13 and the outer lid
14 through axial flow
gaps formed between the outer wall of the housing opening
15 and the inside
of the cylindrical section of the outer lid
14.
As FIG. 4 shows in detail, the locking mechanism
17 which connects the
outer lid
14 to the wall of the housing opening
15 is configured
as a locking thread. The locking thread has sections of different pitch. The section
with the smaller pitch is located in a region adjacent to the locked position of
the outer lid
14, which in FIG. 4 is formed by the lower part of the thread
on the outer wall of the housing opening.
A section with a larger pitch is arranged in the region of the axial end face
of
the housing opening. As a result, when the outer lid
14 is placed onto the
locking thread, a relatively large axial displacement occurs initially along the
longitudinal filter axis
19 in the direction of the locked position because
of the large thread pitch.
In contrast, when the section with the smaller pitch is reached near the tight
seat or the locked position of the outer lid
14, the outer lid is displaced
more slowly in axial direction. As a result, especially if the housing lid is tightened
manually, more force or a better controllable force is available to get a tight seat.
Axial flow grooves may be made in the locking thread to enable the fluid to
flow freely in the outflow space or the discharge path
18.
In addition to the locking mechanism
17 between the wall of the housing
opening
15 and the outer lid
14, an attachment mechanism
20
is provided, which is disposed between the inner lid
13 and the outer lid
14 and enables positive locking in axial direction between the inner and
the outer lid. The attachment mechanism
20 comprises one or more attachment
projections, which are preferably arranged on the outer circumferential side of
the inner lid
13, and an attachment groove formed in the inner lateral surface
of the outer lid
14. The attachment mechanism
20 enables a rotatable
by axially fixed connection between the inner lid and the outer lid.
Advantageously, the latched position is reached only after a tight
seat is achieved. To construct a bayonet lock requiring an axial displacement and
a rotational motion to be executed consecutively, it may furthermore be advantageous
not to make the attachment projections on the outside of the inner lid
13
circumferentially contiguous but with intermittent gaps by distributing, for example,
three individual attachment projections at a 120° angle, which are associated
with correspondingly configured attachment groove sections on the outer lid. The
attachment mechanism
20 represents an additional safeguard against accidental
detachment of the housing lid.
As FIG. 4 further shows, the sealing ring
16 is disposed in a circumferential
sealing groove
21 formed on the outside of the inner lid
13. The
partition of the housing lid
3 into two separate lid parts has the advantage
that there is a functional separation between the inner lid and the outer lid.
The inner lid
13 carries the sealing ring
16, while the outer lid
14 has the function of locking the two lid parts on the filter housing
2
and furthermore protecting the pressure relief valve
8 against dirt.
This functional separation has the further advantage that the sealing ring is
not twisted when the lid is opened and closed, but needs only to be translationally
displaced in the direction of the longitudinal axis
19 together with the
inner lid
13. Since the sealing ring
16, particularly after having
been in its sealing position for a prolonged period of time, can adhere to the
adjacent inner wall of the housing opening
15, less force is required for
a translational axial removal of the inner lid than would be necessary for a rotational
motion. This protects the sealing ring and prevents damage during insertion and removal.
In addition, the two-part configuration of the housing lid
3 has the advantage
of reducing the design complexity of the discharge path
18, which is formed
between these two parts and through which the excess pressure escaping from the
interior of the housing when the valve
8 is open can be discharged toward
the outside.
The inner lid
13, the outer lid
14, the locking mechanism
17
and the attachment mechanism
20 can all be made of synthetic resin material
(i.e., plastic).
FIG. 5 shows a special embodiment of a pressure relief valve
8. The pressure
relief valve
8 has a valve body
22, which must be displaced axially
in displacement direction
26 in a valve body guide
27 between the
closed position shown in FIG. 5 and a lifted, open position. The valve body guide
27 is formed in a housing part
25.
The valve body
22 is urged into the closed position by a valve spring
23, which is supported on a valve disk
24 that is fixed to the valve
body
22. If an overpressure in the interior of the housing exceeds the closing
force of the valve spring
23, the valve body
22 moves to the open
position so that the excess pressure can escape.
To influence the spring characteristic and the opening or closing behavior, the
pressure relief valve
8 is provided with a clamping mechanism
28,
which applies a clamping force to the valve body
22. This clamping force
acts in radial direction as indicated by arrow
29 perpendicularly to the
displacement direction
26 and firmly clamps the valve body
22 in
the valve body guide
27.
The clamping mechanism
28 is fixed to the valve body
22 and comprises
an additional spring
30, which is configured, in particular, as a compression
spring whose spring effect extends in the direction of arrow
29. The additional
spring
30 is connected to latching balls
31 on its two axial end
faces. The force of the additional spring applies a clamping force to these latching
balls
31 in a radially outward direction so that they are pressed into latching
recesses
32 that are formed in the inner wall of the valve body guide
27
and are advantageously adapted to the shape of the latching balls
31.
In the closed position of the valve body
22 the clamping mechanism
28
is in the latching position, so that a higher overpressure is required to move
the pressure relief valve
8 into the open position than in embodiments without
such a clamping mechanism
28. The amount of additional pressure required
to detach the clamping mechanism
28 and to move the valve to the open position
can be influenced through the force of the additional spring
30, the geometry
of the latching elements subject to the pressure of the additional spring, and
the geometry of the latching recesses.
Once the pressure limit above which the valve moves to the open position has
been reached, the latching balls
31, because of the axial displacement of
the valve body in the direction of the open position, are first pushed inwardly
against the force of the additional spring
30 and, as the opening motion
proceeds, fit against the inner wall of the valve body guide
27. The clamping
force exerted by the clamping mechanism on the inner wall of the valve body guide
in the intermediate transitional section between the closed position and the open
position is clearly smaller than the clamping force in the closed position of the
valve. This is true because in the clamping position the clamping mechanism assumes
a positive-locking latched position, while in the intermediate transitional section
it only glides along the inner wall.
Furthermore, it must be taken into account that in the initial position
of the valve body, increased static friction must be overcome between the latching
elements biased by the additional spring and the latching recesses. In contrast,
when the valve body is moving, a smaller gliding effect acts between the latching
elements pushed in outward direction and the inner wall of the valve body guide.
This marked drop of the clamping force changes the overall spring characteristic
and the opening behavior of the valve. Compared to configurations of the prior
art, the valve body can move more rapidly from the closed position to the open
position. The valve can be abruptly actuated to the open position.
The embodiment illustrated in FIG. 6 also shows a pressure relief valve
8,
which is in the closed position and must be moved axially in displacement direction
26 between the closed position and the open position. This valve, like the
valve of the preceding embodiment, has a clamping mechanism
28 applying
pressure to the valve body
22 in the closed position in the direction of
the arrow
29 with a clamping force perpendicular to the displacement direction
26.
Furthermore, a second clamping mechanism
33 is provided, which
is configured correspondingly to the first clamping mechanism
28 and comprises
an additional spring
34 and axial latching balls
35 subject to the
pressure of the additional spring
34. In the open position of the valve
the latching balls
35 engage latching recesses
36 formed in the inner
wall of the valve body guide
27. Thus, the valve body
22 is in a
latched position both in the closed position and in the open position and can be
moved to the respectively opposite end position only with increased force compared
to embodiments without clamping mechanisms.
The closing movement of the valve is supported by the force of the valve spring
23. As soon as the overpressure in the interior of the housing falls below
a limit, the force of the valve spring is sufficient to displace the valve body
22 axially against the remaining overpressure in the interior of the housing
and against the clamping force of the second clamping mechanism
33 in the
direction of the closed position.
Analogous to the opening movement, the valve can be abruptly closed with
the aid of the second clamping mechanism
33 because the clamping force is
abruptly reduced as soon as the latching balls
35 of the second clamping
mechanism
33 are lifted out of their seat in the latching recesses
36.
The foregoing description and examples have been set forth merely to illustrate
the invention and are not intended to be limiting. Since modifications of the described
embodiments incorporating the spirit and substance of the invention may occur to
persons skilled in the art, the invention should be construed broadly to include
all variations within the scope of the appended claims and equivalents thereof.
*
