U.S. patent application number 11/500652 was filed with the patent office on 2007-03-15 for control valve and method for its production.
Invention is credited to Jens Hoppe, Andreas Rohr.
Application Number | 20070056540 11/500652 |
Document ID | / |
Family ID | 37478903 |
Filed Date | 2007-03-15 |
United States Patent
Application |
20070056540 |
Kind Code |
A1 |
Hoppe; Jens ; et
al. |
March 15, 2007 |
Control valve and method for its production
Abstract
The invention relates to a control valve for influencing the
action of a pressure medium on a camshaft adjuster of an internal
combustion engine. A control valve of said type comprises a valve
housing (72), in which a displaceable control piston (71) is
arranged in a blind bore. According to the invention, the valve
housing (72) is produced with a through bore (73) instead of a
blind bore, into which through bore (73) a housing insert (79) is
clipped into a groove (80). The housing insert can serve to support
a pressure spring (76), and can also additionally have recesses, in
the region of which the housing insert (79) serves to form a port,
for example to a tank T.
Inventors: |
Hoppe; Jens; (Erlangen,
DE) ; Rohr; Andreas; (Heroldsbach, DE) |
Correspondence
Address: |
HEDMAN & COSTIGAN P.C.
1185 AVENUE OF THE AMERICAS
NEW YORK
NY
10036
US
|
Family ID: |
37478903 |
Appl. No.: |
11/500652 |
Filed: |
August 8, 2006 |
Current U.S.
Class: |
123/90.17 |
Current CPC
Class: |
F01L 1/3442 20130101;
F16K 31/061 20130101; F01L 2001/34426 20130101; F01L 2001/3444
20130101 |
Class at
Publication: |
123/090.17 |
International
Class: |
F01L 1/34 20060101
F01L001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 9, 2005 |
DE |
102005037480.8 |
Claims
1. Control valve for influencing the action of a pressure medium on
a camshaft adjuster of an internal combustion engine, having a
valve housing (72), a control piston (71) which is arranged in the
valve housing (72) and is axially displaceable under the action of
a spring element (pressure spring 76), and a pressure medium port
(P), a tank port (T) and two working ports (A, B), wherein, for one
axial position of the control piston (71), a first working port (A)
can be connected to the or a tank port (T2), and the second working
port (B) can be connected to the pressure medium port (P), while
for another axial position of the control piston (71), the second
working port (B) can be connected to the or a tank port (T1) and
the first working port (A) can be connected to the pressure medium
port (P), characterized in that the spring element (pressure spring
76) is supported, by means of the foot point (78) situated at the
opposite side from the control piston (71), on a housing insert
(79).
2. Control valve according to claim 1, characterized in that the
housing insert (79) has recesses (88), through which the pressure
medium can pass out of the control valve (70) in order to form a
port (T2).
3. Control valve according to claim 2, characterized in that the
recesses (88) extend inwards from an outer edge (85) of the housing
insert (79).
4. Control valve according to one of the preceding claims,
characterized in that the housing insert (79) is clipped into the
valve housing (72).
5. Control valve according to claim 4, characterized in that, in
longitudinal section, the housing insert (79) is approximately in
the form of the longitudinal section of a hat or of a pot, and the
"brim" (84) of the hat or the edge (85) of the pot is clipped into
a groove (80) of an inner lateral surface (81) of the valve housing
(72).
6. Control valve according to claim 5, characterized in that the
mid-region (86) of the hat-shaped housing insert (79) is conical,
said mid-region (86) adjoining the brim (84).
7. Control valve according to one of the preceding claims,
characterized in that the diameter of a bore (73) for holding the
housing insert (79) approximately corresponds to the diameter of
the region for holding the control piston (71) in an axially
displaceable fashion.
8. Control valve according to one of the preceding claims,
characterized in that the housing insert (79) forms a stop (83) for
the control piston (71), in order to predefine an axial end
position of the control piston (71).
9. Control valve according to one of the preceding claims,
characterized in that the control valve (70) is suitable for being
integrated into a camshaft.
10. Method for producing a control valve for influencing the action
on a camshaft adjuster of an internal combustion engine, in
particular a control valve according to one of claims 1 to 9,
characterized by the following method steps: a) forming a bore (73)
in the valve housing (72), said bore (73) being at least of a
length which permits it to hold both a control piston (71) and also
a housing insert (79), b) forming a groove (80) in the bore (73) of
the valve housing (72), c) radially compressing a housing insert
(79), d) inserting the housing insert (79), in the radially
compressed state, into the bore (73) of the valve housing (72) and
e) radially expanding the housing insert (72) in such a way that
the radially outer edge (85) of the housing insert (79) is received
in the groove (80) of the valve housing (72).
11. Method according to claim 10, characterized in that the bore
(73) is formed in the valve housing (72) in the form of a through
bore.
12. Method according to claim 10 or 11, characterized in that a
housing insert (79) is produced in the form of a "hat", with a
conical mid-region (86), and the housing insert (79) is radially
elastically expanded and compressed by changing the opening angle
(90) of the conical mid-region (86).
13. Method according to claim 12, characterized in that, in order
to insert the housing insert (79) into the valve housing (72), the
housing insert (79) is held in a tool (91) such that the opening
angle (90) of the conical mid-region (86) is reduced.
Description
DESCRIPTION
[0001] 1. Field of the Invention
[0002] The invention relates to a control valve for influencing the
action of a pressure medium on a camshaft adjuster of an internal
combustion engine, in particular according to the preamble of claim
1. The invention additionally relates to a method for producing a
control valve, in particular according to the preamble of claim
10.
[0003] 2. Background of the Invention
[0004] A control valve for influencing the action of a pressure
medium on a camshaft adjuster of an internal combustion engine is
known from the applicant's patent application DE 10 2004 036 096.0,
which was not published before the priority date of the present
application, in which control valve a control piston is axially
displaceable in a blind bore of a valve housing, wherein the action
on a spring element is varied with the displacement of the control
piston. The spring element is supported with one foot point on an
end side of the control piston and with the opposite foot point on
the base of the blind bore of the valve housing. The control valve
has a pressure medium port, two tank ports and two working ports,
which are associated with oppositely-acting working chambers of a
hydraulic camshaft adjuster. In one axial position of the control
piston, in the control valve, a first working port is connected to
a tank port and the second working port is connected to the
pressure medium port, so that it is possible to effect an actuating
movement of the camshaft adjuster during which the working chamber
which is associated with the second working port increases in
volume. In another axial position of the control piston, the second
working port is connected to a tank port and the first working port
is connected to the pressure medium port, so that it is possible to
effect an actuating movement of the camshaft adjuster during which
the working chamber which is associated with the first working port
increases in volume.
OBJECT OF THE INVENTION
[0005] The invention is based on the object of simplifying
production of the control valve mentioned in the introduction while
further ensuring or improving its functions.
SUMMARY OF THE INVENTION
[0006] According to the invention, the object is achieved by means
of a control valve according to the features of independent patent
claim 1. Preferred embodiments of a control valve according to the
invention emerge corresponding to the features of dependent patent
claims 2 to 9. A further solution of the object on which the
invention is based is provided by means of a method according to
independent patent claim 10. Embodiments of the method according to
the invention emerge from dependent patent claims 11 to 13.
[0007] The invention is based on the realization that the
manufacture of the valve housing with a blind bore for holding the
control piston has potential for optimization. Imprecise
manufacture of the position of a base of the blind bore
corresponding to the prior art can in some circumstances influence
the function of the control valve, for example the foot point of a
spring element, an end position of the control piston and/or the
hydraulic conditions, for which reason the blind bore must be
manufactured with a high degree of accuracy. It can additionally be
necessary for the base of the blind bore to have an additional
opening which forms a port, for example a tank port, and for the
production of which a further bore must be formed in the valve
housing in the region of the base of the blind bore. Here,
impurities and burrs must be carefully avoided in the interior of
the valve housing which, in an embodiment with a blind bore, is
only completely open at one side, since said impurities and burrs
can lead, during operation of the control valve, to adverse
mechanical effects, increased wear to the point of failure of the
control valve or of components which are hydraulically connected to
the control valve. On the other hand, the production of a blind
hole requires the use of a special tool, in particular a reamer,
which, for example, makes an additional undercut necessary in the
region of the base of the blind bore. In some circumstances, this
requires an increased installation length of the control valve. In
addition, the shape of the end face of the tool predefines the
shape of the base of the blind bore which can be obtained, so that,
in some circumstances, integration of further functions into the
base of the blind bore is only possible with difficulty. For
example, the base of the blind bore cannot delimit the actuating
movement of the control piston. Such delimitation of the actuating
movement of the control piston is, however, of increased
significance since, for example, when a predefined end position of
the control piston is exceeded, for example as a result of
tolerances of the components of the control valve, the hydraulic
connection to a port is only insufficiently opened or closed. Known
solutions operate in that an end stop of the control piston is
provided by the spring element "being compressed fully" for the end
stop to be reached, wherein the end position is however still
dependent on tolerances, also in the manufacture of the blind
bore.
[0008] According to the invention, the previously explained
realizations are implemented in that the spring element is
supported not on a base of the blind bore, but rather, by means of
the foot point situated at the opposite side from the control
piston, on a housing insert. This means that both the valve housing
and the housing insert can be produced separately, as a result of
which [0009] further manufacturing possibilities can be utilized,
[0010] the housing insert can be produced with defined tolerances,
[0011] the mechanical properties of the housing insert can be
configured in a targeted fashion [0012] and there is greater scope
for configuring the geometry of the housing insert than a base of
the blind bore.
[0013] The embodiment according to the invention having a housing
insert makes it possible, for example, for the bore of the valve
housing for holding the control piston to be formed as a through
bore, so that said bore can be produced more simply and with
greater precision, and the formation of burrs is reliably avoided.
The foot point of the spring element is then exactly predefined by
inserting the housing insert into the valve housing, as a result of
which the position of the foot point can be predefined with high
accuracy. On the other hand, for different control valves, it is
possible in some circumstances for the same valve housing to be
used in connection with different housing inserts, different
positions of the housing insert relative to the valve housing
and/or different support locations of the spring element by means
of different geometries of the housing inserts which are used.
[0014] According to a preferred embodiment of the control valve
according to the invention, the housing insert is embodied in a
multifunctional fashion in that, in addition to the support of the
foot point for the spring element, said housing insert has recesses
through which the pressure medium can pass out of the control valve
in order to form a port, in particular a tank port. The production
of the recesses in a housing insert is simplified with respect to
such production for the design having a blind bore, with additional
configuration possibilities for the recesses, for the number of
recesses and for their distribution over the housing insert also
being provided. By way of example, the recesses can extend inwards
from an outer edge of the housing insert, so that radially
outwardly situated webs or spring lips are formed between the
recesses, which webs or spring lips can advantageously be used for
a connection between the housing insert and the valve housing,
while in some circumstances, a closed central region of the housing
insert is provided in a radially inward region.
[0015] There are many possibilities for a connection between the
housing insert and the valve housing. For example, the connection
can be a form-fitting, force-fitting or cohesive connection. The
housing insert can be pressed or screwed into the valve housing.
According to one particular proposal for a simple design of the
connection of the housing insert to the valve housing, which
connection is also simple to assemble and, if appropriate, to
disassemble, the invention proposes that the housing insert is
clipped into the valve housing.
[0016] According to a refinement of the invention, in longitudinal
section, the housing insert is approximately in the form of the
longitudinal section of a hat or of a pot. By elastically deforming
the housing insert, the "brim" of the hat or the edge of the pot
can be radially compressed and expanded, so that the edge or brim
is clipped into a suitable groove of an inner lateral surface of
the valve housing. Accordingly, for manufacture, only one suitably
formed groove, if appropriate with at least one insertion slope,
must be formed in the lateral surface of the valve housing, while
the housing insert can be produced cost-effectively, for example as
a sheet metal part or a shaped part. The previously mentioned
recesses can be advantageous in promoting the elastic compression
and expansion of the edge or of the brim in the radial direction,
said recesses forming elastic webs or spring lips as mentioned
previously.
[0017] According to a further proposal of the invention, the
mid-region of the hat is conical, said mid-region adjoining the
edge or the brim. The desired deformation for clipping the housing
insert in can be provided in this case by elastically deforming the
conical mid-region and/or by changing the cone angle of the
mid-region. In addition, the conical design of the mid-region
offers improved possibilities for mounting the housing insert into
the valve housing, as will be explained in more detail in the
following.
[0018] According to a refinement of the invention, in addition to
the function of supporting a foot point of the spring element and
the function of forming the recesses for the port, the housing
insert fulfills the additional function of providing a stop for the
control piston, in order to predefine an axial end position of the
control piston. This results in a defined end position of the
control piston, as a result of which insufficient desired opening
positions to one of the ports are avoided. At the same time, it is
possible to avoid the situation where a stop for the control piston
is provided only by the spring element "being compressed fully".
The position of the stop can be predefined exactly by means of the
separately produced housing insert which is inserted into the valve
housing. A spring action and/or damping action for an "impact" of
the control piston against the stop can be obtained by suitably
configuring the mechanical properties of the housing insert and/or
the hydraulic properties in the region of the housing insert.
[0019] A particularly compact design is obtained if the control
valve is suitable for being integrated into a camshaft. This
additionally results, in some circumstances, in short hydraulic
transmission paths between the control valve and the associated
working chambers of the camshaft adjuster.
[0020] To produce a control valve, a bore is initially formed in
the valve housing, said bore being at least of a length which
permits it to hold both a control piston and also a housing insert.
In the simplest case, said bore is a through bore with a constant
cross section, wherein different cross-sectional configurations
along the length of the bore are, however, also possible. In a
subsequent working operation, a groove is formed in the bore of the
valve housing, into which bore a housing insert can later be
clipped. The housing insert is subsequently radially compressed.
Said compression preferably takes place in such a way that the
outer diameter of the housing insert is less than the diameter of
the bore in that region in which the housing insert is inserted
into the valve housing. In said state, the housing insert is then
inserted into the bore of the valve housing, approximately as far
as into the region of the groove, where the housing insert is then
radially expanded, in particular by means of elastic forces of the
housing insert. In the "clipped-in position", the radially outer
edge of the housing insert is ultimately received in the groove of
the valve housing. The radial compression and/or the insertion of
the housing insert into the groove can be assisted by means of
suitable insertion slopes in the region of the valve housing.
Alternatively, or in addition, the compression and expansion can
take place using suitable tools.
[0021] According to a refinement of the invention, the housing
insert has a conical mid-region, wherein the housing insert is
radially elastically expanded and compressed by changing the
opening angle of the conical mid-region.
[0022] Assembly is particularly simple if the housing insert is
held in the compressed state by means of a tool which "retains" the
previously mentioned reduced opening angle of the cone until the
housing insert is arranged in the valve housing at the appropriate
position for expansion.
[0023] Advantageous refinements of the invention emerge from the
dependent patent claims and from the entire description. Further
features can be gathered from the drawings--in particular the
illustrated geometries and the relative dimensions of several
components with respect to to one another and their relative
arrangement and operative connection. The combination of features
of different embodiments of the invention, or of features of
different patent claims, deviating from the selected references
back, is likewise possible and is hereby encouraged. This also
relates to features which are illustrated in separate drawing
figures or are mentioned in the description thereof. Said features
can also be combined with features of different patent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
In the figures:
[0024] FIG. 1 shows a longitudinal section through a device for
changing the control times of an internal combustion engine having
a pressure medium circuit,
[0025] FIG. 2 shows a cross section through the device illustrated
in FIG. 1, along the line II-II,
[0026] FIG. 3 shows a longitudinal section through a control
valve,
[0027] FIG. 4 shows a longitudinal section through a second
embodiment of a control valve,
[0028] FIG. 5 shows a longitudinal section through a third
embodiment of a control valve,
[0029] FIG. 6 shows a longitudinal section though a fourth
embodiment of a control valve,
[0030] FIG. 7 shows a longitudinal section through a further
embodiment of a control valve,
[0031] FIG. 8 shows the control valve according to FIG. 7 in an end
position predefined by a housing insert,
[0032] FIG. 9 shows a front view of a housing insert,
[0033] FIG. 10 shows a longitudinal section of a housing insert
and
[0034] FIG. 11 shows an assembly step for inserting the housing
insert into the valve housing with a tool for holding the housing
insert in a compressed state.
DETAILED DESCRIPTION OF THE DRAWING
[0035] FIGS. 1 and 2 show a device 1 for changing the control times
of an internal combustion engine. The device 1 substantially
comprises a stator 2 and a rotor 3 which is arranged concentrically
with respect thereto. A drive wheel 4 is rotationally fixedly
connected to the stator 2 and in the illustrated embodiment is
embodied as a sprocket. Embodiments of the drive wheel 4 as a belt
or as a gearwheel are likewise conceivable. The stator 2 is
rotatably mounted on the rotor 3, wherein in the illustrated
embodiment, five recesses 5 which are spaced apart from one another
in the circumferential direction are provided on the inner lateral
surface of the stator 2. The recesses 5 are delimited in the radial
direction by the stator 2 and the rotor 3, in the circumferential
direction by two side walls 6 of the stator 2, and in the axial
direction by a first and a second side cover 7, 8. Each of the
recesses 5 is closed off in a pressure-tight manner in this way.
The first and second side covers 7, 8 are connected to the stator 2
by means of connecting elements 9, for example screws.
[0036] Axially running vane grooves 10 are formed on the outer
lateral surface of the rotor 3, with one radially extending vane 11
being formed in each vane groove 10.
[0037] One vane 11 extends into each recess 5, with the vanes 11
bearing against the stator 2 in the radial direction and against
the side covers 7, 8 in the axial direction. Each vane 11 divides a
recess 5 into two pressure chambers 12, 13 which act counter to one
another. In order to ensure that the vane 11 bears against the
stator 2 in a pressure-tight manner, leaf spring elements 15 are
attached between the groove bases 14 of the vane grooves 10 and the
vanes 11, said leaf spring elements exerting a force on the vanes
11 in the radial direction.
[0038] The first and second pressure chambers 12, 13 can be
connected via a control valve 18 to a pressure medium pump 19 or to
a tank 20 by means of first and second pressure medium lines 16,
17. This forms an actuating drive which permits a relative rotation
of the stator 2 with respect to the rotor 3. Here, it is provided
either that all the first pressure chambers 12 are connected to the
pressure medium pump 19 and all the second pressure chambers 13 are
connected to the tank 20, or that the connections are in the exact
opposite configuration. If the first pressure chambers 12 are
connected to the pressure medium pump 19 and the second pressure
chambers 13 are connected to the tank 20, the first pressure
chambers 12 expand at the expense of the second pressure chambers
13. This results in a displacement of the vanes 11 in the
circumferential direction, in the direction illustrated by the
arrow 21. The rotor 3 is rotated relative to the stator 2 as a
result of the displacement of the vanes 11.
[0039] In the illustrated embodiment, the stator 2 is driven by
means of a crankshaft chain drive (not illustrated) which engages
on the drive wheel 4 of said stator 2. It is likewise conceivable
for the stator 2 to be driven by means of a belt drive or toothed
drive. The rotor 3 is connected to a camshaft (not illustrated) in
a force-fitting, form-fitting or cohesive fashion, for example by
means of a press fit or by a screw connection by means of a central
screw. The relative rotation of the rotor 3 with respect to the
stator 2, as a consequence of the inlet or outlet of pressure
medium into or out of the pressure chambers 12, 13, results in a
phase shift between the camshaft and the crankshaft. Targeted inlet
and outlet of pressure medium into the pressure chambers 12, 13 can
therefore be used to vary the control times of the gas exchange
valves of the internal combustion engine in a targeted fashion.
[0040] In the illustrated embodiment, the pressure medium lines 16,
17 are formed as substantially radially arranged bores which extend
from a central bore 22 of the rotor 3 to the outer lateral surface
thereof. A central valve (not illustrated) can be arranged within
the central bore 22, by means of which central valve the pressure
chambers 12, 13 can be connected to the pressure medium pump 19 or
the tank 20 in a targeted fashion. A further option is to arrange a
pressure medium distributor within the central bore 22, which
pressure medium distributor connects the pressure medium lines 16,
17 via pressure medium ducts and annular grooves to the ports of an
externally attached control valve 18.
[0041] The substantially radially running side walls 6 of the
recesses 5 are provided with moldings 23 which extend into the
recesses 5 in the circumferential direction. The moldings 23 serve
as stops for the vanes 11 and ensure that the pressure chambers 12,
13 can be supplied with pressure medium even when the rotor 3
assumes one of its extreme positions relative to the stator 2, in
which position the vanes 11 bear against one of the side walls
6.
[0042] In the event of insufficient pressure medium supply to the
device 1, for example during the starting phase of the internal
combustion engine, the rotor 3 is moved relative to the stator 2 in
an uncontrolled fashion as a result of alternating and drag torques
which the camshaft exerts on said rotor 3. In a first phase, the
drag torques of the camshaft push the rotor relative to the stator
in a circumferential direction which opposes the rotational
direction of the stator, until said rotor and stator come into
contact at the side walls 6. Subsequently, the alternating torques
which the camshaft exerts on the rotor 3 lead to reciprocating
oscillation of the rotor 3 and therefore of the vane 11 in the
recesses 5, until at least one of the pressure chambers 12, 13 is
completely filled with pressure medium. This leads to increased
wear and to noise generation in the device 1. In order to avoid
this, a locking element 24 is provided in the device 1. In
addition, a pot-shaped piston 26 is arranged in an axial bore 25 of
the rotor 3, which pot-shaped piston 26 is acted on with force in
the axial direction by means of a spring 27. The spring 27 is
supported at one side in the axial direction on a ventilation
element 28 and is arranged with its remote axial end within the
pot-shaped piston 26. A slotted guide 29 is formed in the first
side cover 7 such that the rotor 3 can be locked, relative to the
stator 2, in a position which corresponds to the position during
starting of the internal combustion engine. In said position, the
piston 26 is pushed into the slotted guide 29 by means of the
spring 27 when there is insufficient pressure medium supply to the
device 1. In addition, means are provided to push the piston 26
back into the axial bore 25, and therefore to release the locking,
when there is sufficient pressure medium supply to the device 1.
This is conventionally achieved by means of pressure medium which
is conducted via pressure medium lines (not illustrated) into a
cut-out 30 which is formed on the cover-side face end of the piston
26. In order to be able to conduct leakage oil out of the spring
space of the axial bore 25, the ventilation element 28 is provided
with axially running grooves, along which the pressure medium can
be conducted to a bore in the second side cover 8.
[0043] FIG. 1 additionally illustrates the pressure medium circuit
31. A pressure medium port P of a control valve 18 is supplied with
pressure medium from a tank 20 by means of a pressure medium pump
19. At the same time, pressure medium is conducted from the control
valve 18 into the tank 20 via a tank port T. The control valve 18
additionally has two working ports A, B. The control valve 18 can
be placed in 3 positions by means of an electromagnetic actuating
element 32 which acts counter to the spring force of a first spring
element 33. In a first position of the control valve 18, which
corresponds to a state of the actuating element 32 in which no
electrical current is supplied, the working port A is connected to
the tank port T and the pressure medium port P is connected to the
working port B and therefore to the second pressure chamber 13. In
a middle position, both the working port A and the working port B
are disconnected both from the pressure medium port P and from the
tank port T. In a third position of the control valve 18, the
pressure medium port P is connected to the working port A and
consequently to the first pressure chamber 12, while the second
pressure chamber 13 is connected to the tank port T via the working
port B.
[0044] FIG. 3 illustrates a control valve 18 in longitudinal
section. The substantially hollow cylindrical valve housing 34 is
provided with a radial pressure medium port P, a radial tank port
T.sub.1, two working ports A, B and an axial tank port T.sub.2. The
radial ports P, T.sub.1, A, B are formed as first annular grooves
35 which are spaced apart from one another axially and are formed
in the outer lateral surface of the valve housing 34. The first
annular grooves 35 are provided with a plurality of first openings
36 which open out into the interior of the valve housing 34.
[0045] A control piston 37 which is likewise of substantially
hollow cylindrical form is arranged in an axially displaceable
fashion within the valve housing 34. One axial end of the control
piston is delimited in a pressure-tight fashion by means of a wall
section 37a. The wall section 37a can be formed in one piece with
the control piston or can be formed separately from the latter. The
control piston 37 can be placed and held in any desired position
within two extreme values, counter to the spring force of the first
spring element 33, by means of an actuating element 32 (not
illustrated).
[0046] The outer lateral surface of the control piston 37 is
provided with a second, a third and a fourth annular groove 38, 39,
40. The second and the third annular grooves 38, 39 communicate
with the interior of the control piston 37 via second and third
openings 41, 42. The second annular groove 38 is formed in such a
way that it communicates with the first openings 36 of the first
annular groove 35 of the pressure medium port P in all positions of
the control piston 37 relative to the valve housing 34.
[0047] During operation of the internal combustion engine, pressure
medium passes from the pressure medium port P, via the second
annular groove 38 and the second openings 41, into the interior of
the control piston 37. In the first position of the control piston
37, illustrated in FIG. 3, the pressure medium passes via the third
openings 42 and the third annular groove 39 to the working port B.
As a result of the action of pressure medium on the second pressure
chambers 13 via the working port B, pressure medium is pushed out
of the second pressure chambers 12 to the working port A, and
passes to the axially arranged tank port T.sub.2 via the first
openings 36 of said working port A.
[0048] If the electromagnetic actuating element 32 is supplied with
electrical current, the control piston 37 is displaced counter to
the spring force of the first spring element 33. As a result, the
overlap of the first openings 36 of the working port B by a first
control edge 43 of the third annular groove 39 increases. The
overlap of the first openings 36 of the working port A by a second
control edge 44 of the control piston 37 likewise increases. When
the control piston 37 reaches a middle position (not illustrated),
the working port A is no longer connected to the axial tank port
T.sub.2 as a result of complete overlap of the second control edge
44. In addition, neither the working port A nor the working port B
communicates with the third annular groove 39. Alternatively, the
control piston 37 can be designed in such a way that, in the middle
position, both working ports A, B communicate with the third
annular groove 39.
[0049] If the control piston 37 is displaced further counter to the
spring force of the first spring element 33, a third control edge
45 unblocks the first openings 36 of the working port A to the
third annular groove 39. Pressure medium which flows in from the
pressure medium port P now passes only to the working port A. At
the same time, the fourth annular groove 40 communicates both with
the working port B and with the radial tank port T.sub.l. In this
way, pressure medium passes from the pressure medium pump 19 into
the first pressure chambers 12 which leads to a relative rotation
of the rotor 3 with respect to the stator 2. The pressure medium
which is pushed out of the second pressure chambers 13 passes via
the working port B and the fourth annular groove 40 to the radial
tank port T.sub.1. The third control edge 45 and the fourth annular
groove 40 can be formed in such a way that, during displacement of
the control piston 37, the working port A is initially connected to
the pressure medium pump 19 and the working port B is then
connected to the tank 20. Alternatively, both connections can be
produced at the same time.
[0050] A substantially cylindrical filter 46 is arranged within the
control piston 37. The filter 46 comprises a frame 47, preferably
made from plastic, and at least one filter section 48. The filter
section 48 is preferably composed of a mesh of plastic or metal,
with the frame 47 being non-detachably connected to the filter
sections 48. At the axial ends of the filter 46, the frame 47 has
in each case one substantially circular segment 49, with the
circular segments 49 being connected to one another by means of a
plurality of longitudinal struts 50. The filter 46 is fixed within
the control piston 37 in a force-fitting fashion by means of the
circular segments 49. Here, it is advantageous to form an axial
stop 51 within the control piston 37, said axial stop 51 serving as
a travel delimitation when pressing the filter 46 into the control
piston 37. Alternatively, the filter 46 can be pressed in in a
manner which is controlled in terms of travel.
[0051] The filter 46 is arranged in the region of, and completely
overlaps, the second openings 41. The filter 46 bears, at one of
its axial ends, against the axial stop 51. The other axial end
rests on a pot-shaped sleeve 52 which is fixed in the interior of
the control piston 37 in a force-fitting manner. This ensures that
the filter 46 maintains its position during operation of the
internal combustion engine.
[0052] The sleeve 52 additionally closes off the control piston 37
in the axial direction and can serve as an engagement point of a
plunger rod (not illustrated) of the actuating element 32.
[0053] The circular segments 49 of the filter 46 are connected in
the radial direction to an inner lateral surface 53 of the control
piston 37 in a pressure-tight manner, while a gap 54 is provided
between the longitudinal struts 50 and the inner lateral surface
53.
[0054] Pressure medium flowing in from the pressure port P passes
via the second openings 41 into an annular groove which is formed
between the filter sections 48 and the inner lateral surface 53 and
runs around the filter 46. The pressure medium passes via the
filter sections 48 into the interior of the control piston 37, as a
result of which any impurities which are present in the pressure
medium are effectively kept away from the control edges 43, 44,
45.
[0055] FIG. 4 illustrates a further embodiment of a control valve
18. The design and function of said variant are approximately
identical to the first embodiment. In contrast to the first
embodiment, no axial stop 51 is formed in the inner lateral surface
53 of the control piston 37 here. During assembly of the control
valve 18, the filter 46 is pressed into the control piston 37 in a
manner which is controlled in terms of travel. In said embodiment,
a non-return valve 55 is arranged between the filter 46 and the
working ports A, B. Said non-return valve 55 comprises a housing 56
which is arranged within the control piston 37 in a force-fitting
manner. A blocking body 57, which is pressed into a seat 59 of the
non-return valve 55 by means of a second spring element 58, is
situated within the housing 56. Instead of the ball non-return
valve illustrated here, other embodiments, for example a plate
non-return valve, can also be used.
[0056] Pressure medium flowing into the control valve 18 passes to
the non-return valve 55 after passing through the filter 46. As a
result of the arrangement of the filter 46 directly downstream of
the pressure port P, the control edges 43, 44, 45 and the
non-return valve 55 are effectively protected from damage on
account of dirt particles in the pressure medium. Above a certain
pressure within the control piston 37, the blocking body 57 is
displaced counter to the spring force of the second spring element
58, and pressure medium can pass to the working ports A, B via
fourth openings 60, which are formed in the housing 56, and the
third openings 42.
[0057] During operation of the internal combustion engine, pressure
pulsations are generated within the device 1 as a result of
alternating torques of the camshaft. In the process, pressure peaks
occur which are transmitted into the hydraulic system and can
damage other consumers. The arrangement of a non-return valve 55
between the pressure chambers 12, 13 and the pressure medium port P
prevents transmission of said pressure peaks into the hydraulic
system. This protects both the pressure medium pump 19 and further
consumers which are connected to said pressure medium circuit. In
said embodiment, the non-return valve 55 is advantageously arranged
within the control piston 37, and thus requires no additional
installation space. A further advantage is that, specifically when
using the control valve 18 as a central valve, the path between the
location at which the pressure pulsations are generated and the
non-return valve 55 is a minimum. Pressure fluctuations are
intercepted practically at the point of generation.
[0058] FIG. 5 illustrates a further embodiment of a control valve
18. The design and function of said control valve 18 are
approximately identical to the variant shown in FIG. 4. In this
embodiment, the filter 46 is advantageously arranged within the
housing 56 of the non-return valve 55. The housing 56 can be
embodied as a cost-effective plastic shaped part. By integrating
the filter 46 into the housing 56 of the non-return valve 55, the
assembly outlay when assembling the control valve 18 is reduced
considerably. Only one component must now be positioned and
fastened within the control piston 37.
[0059] In this embodiment, that face end of the control piston 37
which faces away from the tank port T.sub.2 is formed such that it
is closed off. The housing 56 is H-shaped in longitudinal section,
with the filter 46 being arranged in one chamber of the H and the
blocking body 57 with the second spring element 58 being arranged
in the other chamber. The second spring element 58 is supported on
a closure 61. The radially running part of the housing 56 is
provided with an opening which is matched to the blocking body 57
and serves as a seat 59.
[0060] FIG. 6 shows a fourth variant of a control valve 18, in
which a control piston 37 is arranged in an axially displaceable
fashion within a substantially hollow cylindrical valve housing 34.
The control piston 37 is likewise of substantially hollow
cylindrical design, with that end side which faces toward the
axially aligned pressure medium port P being formed such that it is
open. The outer lateral surface of the control piston 37 is
provided with a first annular groove 35 and a group of first
openings 36.
[0061] During operation of the internal combustion engine, pressure
medium passes into the interior of the valve housing 34 via the
axially aligned pressure medium port P. Depending on the position
of the control piston 37 within the valve housing 34, the pressure
medium passes either via second openings 41 to the working port B
or via third openings 42 to the working port A. At the same time,
the respective working port A, B which is not being acted on by
pressure medium is connected via the first annular groove 35 to the
tank port T.
[0062] A filter 46 is arranged between the pressure medium port P
and the working ports A, B. The filter 46 is formed in the shape of
a pot and comprises a frame 47 and filter sections 48. At the side
which faces toward the pressure port P, the frame 47 is provided
with a radially extending collar which serves as an axial stop of
the filter 46. In addition, it is possible to fix the filter 46 to
the valve housing 34 in a form-fitting, force-fitting or cohesive
manner. As in the embodiments described previously, a non-return
valve 55 can also be arranged between the pressure medium port P
and the working ports A, B here.
[0063] A control valve 70 according to the invention has a control
piston 71 which is arranged in a valve housing 72 in an axially
displaceable fashion. The control valve 70 and the control piston
71 are, for example, formed corresponding to one of the exemplary
embodiments illustrated in FIGS. 1 to 6. However, the bore 73 of
the valve housing 72 is formed according to FIG. 7 as a through
bore of constant diameter, with end-side chamfers 74, 75 which
widen outwards. A pressure spring 76, which substantially
corresponds to the spring element 33 in the exemplary embodiments
of FIG. 1 to FIG. 6, has a foot point 77, which is supported on an
end side of the control piston 71, and a foot point 78, which is
supported on a housing insert 79. The housing insert 79 is clipped
into a groove 80 of the inner lateral surface 81 of the valve
housing 72. In the region of that end face of the control piston 71
which bears against the foot point 77, the control piston 71
radially surrounds the pressure spring 76 by means of an annular
shoulder 82, resulting, in some circumstances, in the pressure
spring 76 being guided. In addition, a stop 83, here having an
annular stop face, projects from the annular shoulder 82 in the
direction of the housing insert 79, said stop 83 coming into
contact with the housing insert 79 in the end position of the
control valve 70 as illustrated in FIG. 8.
[0064] FIG. 9 shows a front view of the housing insert 79, while
FIG. 10 shows a longitudinal section of the housing insert 79. The
housing insert 79 is substantially of pot-shaped or hat-shaped form
with [0065] a circular brim 84 having a radially outer edge 85
which is received in the groove 80, [0066] a conical mid-region 86
and [0067] an approximately circular central region 87.
[0068] As illustrated in FIG. 7, the pressure spring 78 is held in
the mid-region 86, so that, in some circumstances, the housing
insert 79 can radially guide the pressure spring 76. According to
FIG. 9, three notches or recesses 88 extend radially inwards from
the edge 85, said notches or recesses 88 [0069] being approximately
rectangular in the exemplary embodiment illustrated in FIG. 9,
[0070] ending approximately in the central region 78 or the edge
thereof and [0071] being uniformly distributed about the
circumference.
[0072] Annular corners 89 or tapers are provided in the transition
region between the recesses 88 and the edge 85, said annular
corners 89 or tapers, together with the rest of the design of the
housing insert 79, being intended to prevent the housing insert 79
becoming jammed in the valve housing during assembly. The conical
mid-region 86 has an opening angle 90. For elastic radial
compression of the housing insert 79, the opening angle 90 is
reduced and/or the mid-region 86 is elastically deformed. During
radial expansion for clipping the housing insert 79 into the groove
80, the opening angle 90 increases again.
[0073] The housing insert 79 is preferably inserted into the valve
housing 72 using a tool 91 according to FIG. 11. The tool 91 is
rotationally symmetrical about the longitudinal axis 95-95. The
tool 91 has a central blind bore which can be of cylindrical or
conical form. In each case, the opening angle of the blind bore 92
is less than the opening angle 90 of the housing insert 79 in the
expanded state. Consequently, the conical mid-region is radially
outwardly pressed against the inner face of the blind bore and is
held therein in a force-fitting manner. Accordingly, the housing
insert 79 can be inserted in the radially compressed state into the
blind bore 92, with the outer diameter of the housing insert 79
approximately corresponding to the diameter of the bore 73 or being
less than said diameter. In said state, the housing insert 79 can
be inserted into the valve housing 72 by means of the tool 91, as
illustrated in FIG. 11. Here, a shoulder 93 of the tool 91 can
predefine how far the tool 91, with the housing insert 79, can be
pushed into the valve housing 72. When the housing insert 79 is
approximately in the region of the groove 80, the housing insert 79
can be pushed out of or ejected from the tool 91. Here, an ejecting
force can be exerted on the housing insert 79 by means of an
auxiliary device which is inserted into a longitudinal bore 94
which opens out into the blind bore 92. If the blind bore 92 is
conical rather than cylindrical, the radial outer diameter of the
housing insert 79 can be increased continuously with
displacement.
[0074] The recesses 88 form a flow cross section to the port, for
example in the direction of the tank. Here, a suitable selection of
the ratio between the flow cross sections at port B in the control
valve 70 and the recesses 88 is significant. If the outflow cross
section, which is predefined by the recesses 88, is too small
relative to the flow cross sections of the other ports involved, an
undesired dynamic pressure can build up in the valve.
[0075] In an assembly process, the housing insert 79 can be
supplied continuously, for example by means of an oscillating
conveyer. Through suitable selection of the geometry of the housing
insert, of the sheet metal thickness, and by specifying the
curvatures and the opening angle 90 as well as the material and
suitable material treatment processes, the force required for
deforming the housing insert 79 and the securing effect which can
be obtained by clipping the housing insert 79 into the groove 80
can be structurally predefined. The mechanical strength of the
housing insert 79 and/or the surface hardness, in particular in the
support region of the pressure spring 76, is preferably increased
by means of case-hardening and tempering.
LIST OF REFERENCE SYMBOLS
[0076] 1 Device
[0077] 2 Stator
[0078] 3 Rotor
[0079] 4 Drive wheel
[0080] 5 Recesses
[0081] 6 Side wall
[0082] 7 First side cover
[0083] 8 Second side cover
[0084] 9 Connecting element
[0085] 10 Vane groove
[0086] 11 Vane
[0087] 12 First pressure chamber
[0088] 13 Second pressure chamber
[0089] 14 Groove base
[0090] 15 Leaf spring element
[0091] 16 First pressure medium line
[0092] 17 Second pressure medium line
[0093] 18 Control valve
[0094] 19 Pressure medium pump
[0095] 20 Tank
[0096] 21 Arrow
[0097] 22 Central bore
[0098] 23 Moldings
[0099] 24 Locking element
[0100] 25 Axial bore
[0101] 26 Piston
[0102] 27 Spring
[0103] 28 Ventilation element
[0104] 29 Slotted guide
[0105] 30 Cut-out
[0106] 31 Pressure medium circuit
[0107] 32 Actuating element
[0108] 33 First spring element
[0109] 34 Valve housing
[0110] 35 First annular groove
[0111] 36 First openings
[0112] 37 Control piston
[0113] 37 a Wall section
[0114] 38 Second annular groove
[0115] 39 Third annular groove
[0116] 40 Fourth annular groove
[0117] 41 Second opening
[0118] 42 Third opening
[0119] 43 First control edge
[0120] 44 Second control edge
[0121] 45 Third control edge
[0122] 46 Filter
[0123] 47 Frame
[0124] 48 Filter section
[0125] 49 Segment
[0126] 50 Longitudinal struts
[0127] 51 Axial stop
[0128] 52 Sleeve
[0129] 53 Lateral surface
[0130] 54 Gap
[0131] 55 Non-return valve
[0132] 56 Housing
[0133] 57 Blocking body
[0134] 58 Second spring element
[0135] 59 Seat
[0136] 60 Fourth opening
[0137] 61 Closure
[0138] 70 Control valve
[0139] 71 Control piston
[0140] 72 Valve housing
[0141] 73 Bore
[0142] 74 Chamfer
[0143] 75 Chamfer
[0144] 76 Pressure spring
[0145] 77 Foot point, left
[0146] 78 Foot point, right
[0147] 79 Housing insert
[0148] 80 Groove
[0149] 81 Lateral surface
[0150] 82 Annular insert
[0151] 83 Stop
[0152] 84 Brim
[0153] 85 Edge
[0154] 86 Mid-region
[0155] 87 Central region
[0156] 88 Recesses
[0157] 89 Annular corner
[0158] 90 Opening angle
[0159] 91 Tool
[0160] 92 Blind bore
[0161] 93 Shoulder
[0162] 94 Bore
[0163] 95 Longitudinal axis
[0164] P Pressure medium port
[0165] T Tank port
[0166] T.sub.1Radial tank port
[0167] T.sub.2Axial tank port
[0168] A First working port
[0169] B Second working port
* * * * *