EP2373874B1 - Hydraulic directional valve - Google Patents

Description

Field of the invention

The invention relates to a hydraulic directional control valve with a valve housing and a filter element, wherein at least one circumferentially extending groove is provided on the valve housing, wherein the filter element is disposed in the groove and at least one frame member and a fixedly connected to this filter fabric and wherein the groove a groove bottom and two substantially in the radial direction and circumferential direction extending side walls and a method for producing the directional control valve.

Such directional valves are used in internal combustion engines, for example for controlling hydraulic camshaft adjusters or switchable cam followers, for example switchable drag levers, bucket tappets or roller tappets. The directional control valves consist of an actuating unit and a valve section. The actuating unit may be, for example, an electromagnetic or hydraulic actuator. The valve section represents the hydraulic section of the directional control valve, wherein an inlet connection, at least one working connection and a tank connection are usually formed on the latter. By means of the actuator targeted specific connections of the valve section can be hydraulically connected to each other and thus the pressure medium flows are directed.

For the use of a directional control valve for controlling a camshaft adjuster, this is normally designed as a 4/3 proportional directional control valve. Such a proportional valve is for example in the DE 100 27 080 A1 disclosed.

The valve section consists of a valve housing and a control piston arranged axially displaceable therein. The valve housing is usually arranged within a cylindrical, blind hole-like receptacle of the cylinder head or a central bore of the camshaft adjuster. On the outer circumferential surface of the valve housing four annular grooves are formed in the groove bottom openings are formed, which serve as pressure medium connections. In the cylinder head, a pressure medium channel is formed per annular groove, which opens into the respective annular groove. Via the connections, pressure medium can enter the interior of the valve housing or emerge from the interior of the valve housing. In the interior of the valve housing, a control piston is arranged axially displaceable, wherein the outer diameter of the control piston is adapted to the inner diameter of the valve housing. Furthermore, ring grooves are likewise formed on the control piston, via which adjacent pressure medium connections can be connected to one another,

Inside the actuator, a coil and an armature are arranged. By energizing the coil, the armature is displaced in the axial direction, wherein this movement is transmitted to the control piston by means of a push rod attached to the armature. Furthermore, a spring acts on the control piston, which is supported on the valve housing and acts on the piston in the axial direction to the actuating unit with a force.

Directional valves for controlling switchable cam followers are usually designed as switching valves. Such a switching valve is, in one embodiment as a 3/2-way valve, for example, from DE 103 59 363 A1 known. The function and design of the electromagnetic actuator are largely analogous to that of the proportional valve.

In this case, an inlet connection, a working connection and a tank connection are formed on the valve section. The working connection communicates via a respective valve seat designed as opening with both the inlet and the tank connection. Within the valve housing, a control piston is further arranged, formed on which two closing elements are. Each closing element can, depending on the position of the control piston within the valve housing, block or release the pressure medium flow through one of the valve seats. Depending on the axial position of the control piston, the working connection can thus be selectively connected to the inlet connection or to the tank connection. The axial position of the control piston is in turn set via the axial position of the armature relative to the second magnetic yoke.

In the DE 100 27 080 A1 Each of the hydraulic connections is assigned a ring filter. Each ring filter is positioned in one of the annular grooves, each ring filter extending along the entire circumferential direction of the circular groove bottom. The ring filter has a frame element made of an elastic plastic. The frame member has two extending in the circumferential direction of the valve housing part elements which face each other in the axial direction and are connected to each other via cross braces. Between the sub-elements and the cross struts a filter fabric is arranged. The filter fabric can be inserted for example in the production of the frame member as an injection molded part in the injection mold and molded with the plastic. The frame member is flexible and has in the circumferential direction two opposing open ends, which can be connected to each other by means of a closure after inserting the ring filter in the groove.

A disadvantage of this embodiment is that the cross struts of the frame member, with a slight misalignment of the ring filter to the valve housing, radially to the openings of the terminals or directly adjacent to the opening of the formed in the cylinder head pressure fluid channel, with which the annular groove communicates, can be arranged. The misalignment can be caused during operation, for example, by the flow forces of the pressure medium and the game between the annular groove and the frame member. This results in a significant throttling of the pressure medium flow through the directional control valve, resulting in an unwanted, time-varying change the way valve characteristic, and thus in the worst case leads to failure of the control of the connected hydraulic consumer,

The US 2003/0226593 A1 shows a hydraulic Wegeventi mi9t a valve housing and a filter element. Enlang the circumference of the valve housing extends a groove in which the filter element is arranged. The filter element consists of a frame and a filter fabric. The groove is designed such that along a peripheral portion extending in the axial direction recesses narrow the width of the groove. The frame element is adapted to the geometry of the groove.

The WO 2008/03487 A1 has a hydraulic control valve to the object with a circumferential groove and a filter element inserted therein. At a portion along the circumference, the side walls of the groove indentations, engage in the bulges of the Filterlements.

Summary of the invention

The invention is therefore based on the object to avoid these disadvantages and thus to provide a hydraulic directional control valve having at least one filter element to protect one of the hydraulic connections from contamination of the pressure medium, wherein the intended valve characteristic over the entire life of the internal combustion engine is to be maintained.

According to the invention the object is achieved in that at least one of the side walls has at least one axial bulge which extends in the direction of the frame member and engages positively and or non-positively on the frame member.

The example cylindrical valve housing of the hydraulic directional valve has a groove which extends in the circumferential direction of the valve housing and is formed for example as an annular groove. The groove has a groove bottom in which radial openings are formed, via which the groove communicates with the interior of the valve housing. Thus, the groove acts as a hydraulic connection, can get into the interior of the valve housing via the pressure medium or can escape from this. Within the groove, the filter element, which may for example be designed as a ring filter, arranged. The filter element has a filter fabric, which is bounded by a frame element, which is made for example of a suitable plastic. In the case of a ring filter, the frame element on two circular sub-elements, which are arranged axially to each other and connected to each other via axial struts. The dimensions of the frame member are adapted to the dimensions of the groove such that pressure medium, which is supplied to the interior of the valve housing or discharged therefrom, must pass through the filter fabric. This ensures that impurities in the pressure medium do not get into the interior of the valve housing. The groove is designed to be open radially outward and is bounded radially inward by a groove bottom, for example of a cylinder jacket, and in the axial direction by a respective, for example, annular side wall. On at least one of the side walls, an axial protrusion is formed, which extends to the frame member. By means of the bulge, the filter element is secured against movements in the circumferential direction of the valve housing. This can be realized by a Formund or adhesion between the bulge and the frame member. The bulge can be formed, for example, only in a certain area of the side wall. Alternatively, the bulge may be formed, for example, along the entire extension of the groove in the circumferential direction. This prevents that the filter element unintentionally shifts out of its installation position at Druckmitteldurchfluss.

It can be provided that the bulge rests positively on an axial side surface of the frame member. The filter element is in this case under axial bias to the bulge. This can be realized that after inserting the filter element into the groove material of the side wall in the axial direction, for example by means of a caulking, is moved. The frame member is clamped in this case between the bulge and the opposite side wall. Advantageously, the frame element projects beyond the groove in the radial direction. This ensures that the axially extending bulge acts on the axial side surface of the frame element.

In an alternative embodiment it can be provided that the bulge is at least partially disposed radially outside of the frame member and frictionally rests against a radially outer surface, for example, the peripheral surface of the frame member. The filter element is pressed in this case radially inwardly against the groove bottom.

In a further alternative embodiment it can be provided that the bulge engages in a recess, for example a recess, of the frame element. In this case, recesses may be provided on the frame element, for example in an axial or radial side surface, into which material of the side wall is displaced. Alternatively, the material of the protrusion may dig into the frame member during its manufacture. Thus, the recesses of the frame member and the bulge of the side wall act as a stop and a counter-stop, whereby a movement of the filter element relative to the bulge and thus the groove bottom are prevented. In addition, in this embodiment, the bulge engage frictionally on the boundary walls of the recess.

Thus, relative movements between the filter element and the bulge are effectively prevented.

In a concretization of the invention it is provided that at least the side wall, which is provided with the bulge, is step-shaped, wherein the frame member is at least partially and the bulge are arranged radially within the step. In this case, after inserting the filter element into the groove, the caulking tool can engage the step to form the protrusion. Material of the step which is displaced radially outward during the stemming process is thus still located radially inside the groove. Thus, it is prevented that on the valve body a radial projection arises, whereby an assembly of the valve housing would be prevented in the recording.

• Einlegen des Filterelements in die Nut und
• Ausbilden zumindest einer axiale Ausbuchtung an zumindest einer der Seitenwände, die sich in Richtung des Rahmenelements erstreckt und form- und oder kraftschlüssig an dem Rahmenelement angreift.

The inventive method for producing a hydraulic directional control valve according to the invention comprises at least the following method steps:

• Insert the filter element into the groove and
• Forming at least one axial bulge on at least one of the side walls, which extends in the direction of the frame member and engages positively and or non-positively on the frame member.

In this case, the bulge may be formed, for example, by means of a caulking process, by means of an embossing process or ring embossing process. After inserting the filter element into the annular groove, for example by means of a caulking pressure on the valve housing, such as the stage, be exercised, so that the axial bulge is formed and comes to rest on the frame member, digging into the frame member or in the recess of the Engages frame element. Alternatively, the radially outer edge of the side wall or the step, for example by means of an embossing process or rolling process can be displaced in the axial direction such that the displaced material (the bulge) presses the frame member against the groove bottom.

Advantageously, the filter element is first inserted into the groove and then formed the bulge.

Brief description of the drawings

Figur 1

ein erfindungsgemäßes hydraulisches Wegeventil in einer Draufsicht,

Figur 2

die Einzelheit Z aus Figur 1 im Längsschnitt,

Figur 3

die Einzelheit Z aus Figur 1 einer weiteren erfindungsgemäßen Ausführungsform eines hydraulischen Wegeventils im Längsschnitt.

Further features of the invention will become apparent from the following description and from the drawings, in which embodiments of the invention are shown in simplified form. Show it

FIG. 1

an inventive hydraulic directional control valve in a plan view,

FIG. 2

the detail Z out FIG. 1 in longitudinal section,

FIG. 3

the detail Z out FIG. 1 a further embodiment of the invention a hydraulic directional control valve in longitudinal section.

Detailed description of the drawing

FIG. 1 shows a hydraulic directional control valve 1 according to the invention in a plan view, using the example of a 4/3-Wegeproprtionalventils directional control valve 1. The directional control valve 1 consists of an actuator 2 and a valve section 3. Such directional control valves 1 are used for example for the control of hydraulic camshaft adjusters.

The valve section 3 of the directional control valve 1 is usually accommodated in a receptacle of a surrounding construction, for example a cylinder head or a cylinder head cover. The valve section 3 has a substantially cylindrically designed valve housing 6 and a control piston 7. The valve housing 6 is formed as a separate component and firmly connected to the actuator 2.

On the outer circumferential surface 8 of the valve housing 6, a plurality of grooves 9, in the illustrated embodiment, annular grooves formed, which are designed to be open radially outward. The grooves 9 are bounded radially inwardly by a respective cylinder jacket-shaped groove bottom 10 and in the axial direction by an annular side wall 4. The grooves 9 communicate via openings 11 formed in the groove bottoms 10 with the interior of the substantially hollow cylindrical valve housing 6. The openings 11 of the grooves 9 and the electromagnetic actuator 2 facing away from the opening 11 of the valve housing 6 serve as pressure medium connections A, B, P, T.

Within the valve housing 6, the control piston 7 is arranged axially displaceable. On the outer circumferential surface of the control piston 7 are as ring lands executed control sections 12 are formed. The outer diameter of the control sections 12 is adapted to the inner diameter of the valve housing 6. By means of a suitable axial positioning of the control piston 7 relative to the valve housing 6, adjacent pressure medium connections A, B, P can be connected to one another. The work connection A, B which is not connected to the feed connection P is simultaneously connected to the tank connection T. In this way, the individual pressure chambers of the camshaft adjuster pressure medium can be selectively supplied or derived from these.

The control piston 7 is acted on one end with the force of a spring element, not shown, in the direction of the electromagnetic actuator 2. At the other axial end of the control piston 7 is located on a push rod, not shown, which is connected to an armature of the actuator 2, not shown.

In the de-energized state of the actuator 2, the control piston 7 is urged in the direction of the electromagnetic actuator 2 due to the force of the spring element. By energizing the actuator 2, the control piston 7 is moved against the force of the spring element.

Within the central groove 9, a filter element 13, in the illustrated embodiment, a ring filter is arranged, which extends along the entire circumference of the groove 9. The filter element 13 has a frame element 14 and a filter fabric 15. The frame member 14 comprises two extending in the circumferential direction of the valve housing 6 sub-elements 16 which are interconnected by means of axially extending transverse struts 17. Between the partial elements 16 and the transverse struts 17, the filter fabric 15 is arranged. In order to keep a disturbance of the pressure medium flow through the filter element 15 as low as possible, the transverse struts 17 are advantageously arranged between the openings 11. Pressure medium which is conveyed by the pressure medium pump, not shown, to the central groove 9, passes through the filter fabric 15 to the openings 11 and thus into the interior of the directional control valve 1, wherein foreign matter located in the pressure medium are kept away from the interior of the directional control valve 1.

FIG. 2 shows the detail Z out FIG. 1 in longitudinal section. The frame member 14 is completely disposed within the groove 9 and abuts against the side walls 4. At the radially outer end of the side walls 4 in each case an annular bulge 5 is formed, which extends in the axial direction. In this case, the bulge 5 is formed such that it presses the frame member 14 against the groove bottom 10. Thus, a frictional connection between the groove base 10, the frame member 14 and the protrusions 5 is made, which prevents movement of the filter element 13 relative to the groove bottom, in particular a rotation of the ring filter. The bulge 5, for example, on the peripheral surface of the frame member 14 abut ( FIG. 2 left side) or on the corner of the frame element 14 act ( FIG. 2 right side). In addition, 14 recesses may be provided at the corners of the frame member, in which engage the bulges 5, which in addition to the force closure is made a positive connection in the circumferential direction.

The assembly of the filter element 13 extends in several steps. After the manufacture of the valve housing 6, the filter element 13 is positioned in the groove 9. The side walls 4 have no bulges 5 at this time. Thus, the filter element 13 can easily insert into the groove 9. Subsequently, the bulges 5 are produced, for example, by means of a ring embossing process. Likewise conceivable are embodiments in which instead of the annular bulge 5 only local bulges 5 are formed. These can be produced, for example, by means of an embossing or caulking process.

Thus, it is excluded that the filter element 13 is rotated by the flow forces of the pressure medium in the circumferential direction relative to the valve housing 6.

FIG. 3 shows an alternative embodiment of a hydraulic directional control valve 1 in the illustration of FIG. 2 , In this embodiment, the side walls 4 are step-shaped in the radial direction. The groove 9 thus has a radially outer portion with a larger axial extent and a radially inner portion Section with smaller axial extent on. The areas are connected via a step 18. In the illustrated embodiment, the step 18 is straight and arranged at right angles to the sections of the side walls 4, although other embodiments are conceivable. The filter element 13 is positioned in the radially inner portion of the groove 9, wherein the frame member 14 abuts the inner portions of the side walls 4 and the step 18 projects beyond in the radial direction. The radially inner portion of the side wall 4 has below the step 18 on a bulge 5 extending in the axial direction. The bulge 5 engages in a depression 19, for example a recess formed on the frame element 14, on an axial side surface of the left part element 16 of the frame element 14. Thus, there is a positive connection between the side wall 4 and the filter element 13, which prevents a rotation of the filter element 13 in the groove 9. In addition, the bulge 5 may be formed such that it rests in the recess non-positively on the frame member 14, whereby larger forces can be intercepted in the circumferential direction. Likewise conceivable are embodiments in which no indentations 19 are provided on the frame element 14, but the bulges 5 only rest non-positively on an axial side surface of the part or elements 16. The assembly of the filter element 13 extends in several steps. After the manufacture of the valve housing 6, the filter element 13 is positioned in the groove 9 in the radially inner portion. The side walls 4 have no bulges 5 at this time. Thus, the filter element 13 can easily insert into the groove 9. Subsequently, the bulges 5 are produced, for example, by means of a caulking process. In this case, a stamp is pressed onto the step 18, whereby material of the side wall 4 is displaced in the axial direction, whereby the bulge 5 is formed. In addition to the embodiment in which the frame member is provided with recesses and embodiments are conceivable in which the frame member 14 prior to the formation of the bulge 5 has no recess, but the displaced material that will form the bulge 5, during the Verstemmvorgangs in the frame member 14 digs. In this case, there is automatically an additional frictional connection between the side wall 4 and the frame member 14 before. Since the frame element 14 projects beyond the step 18 in the radial direction, it is ensured that the bulge 5 acts on the frame element 14. Furthermore, it is prevented that material of the stage 18, which is displaced during the Verstemmvorgangs in the radial direction, protrudes beyond the groove 9 and thus the insertion of the valve housing 6 in the recording of the surrounding structure would be difficult or impossible.

Alternatively or additionally, in both embodiments by means of bulges 5 fastened filter elements 13 may be provided in the outer grooves 9, which serve as working ports A, B. The bulges can be formed on one or both side walls 4.

reference numeral

1

way valve

2

actuator

3

valve section

4

Side wall

5

bulge

6

valve housing

7

spool

8th

Outer casing surface

9

groove

10

groove base

11

opening

12

control section

13

filter element

14

frame element

15

filter cloth

16

partial elements

17

crossmember

18

step

19

deepening

P

inflow connection

T

tank connection

A

first work connection

B

second work connection

Claims (10)

1. Hydraulic directional valve (1) having a valve housing (6) and a filter element (13),

   - at least one groove (9) which extends in the circumferential direction being provided on the valve housing (6),

   - the filter element (13) being arranged in the groove (9) and having at least one frame element (14) and a filter fabric (15) which is connected fixedly to said frame element (14), and

   - the groove (9) having a groove bottom (10) and two side walls (4) which extend substantially in the radial direction and circumferential direction,

   - characterized in that at least one of the side walls (4) has at least one axial bulge (5) which extends in the direction of the frame element (14) and acts on the frame element (14) in a nonpositive manner.
2. Hydraulic directional valve (1) according to Claim 1, characterized in that the bulge (5) bears nonpositively against an axial side face of the frame element (14).
3. Hydraulic directional valve (1) according to Claim 2, characterized in that the frame element (14) protrudes beyond the groove (9) in the radial direction.
4. Hydraulic directional valve (1) according to Claim 1, characterized in that the bulge (5) is arranged at least partially radially outside the frame element (14) and bears nonpositively against a radially outer face of the frame element (14).
5. Hydraulic directional valve (1) according to Claim 1, characterized in that the bulge (5) engages into a depression (19) of the frame element (14).
6. Hydraulic directional valve (1) according to Claim 1, characterized in that at least the side wall (4) which is provided with the bulge (5) is of stepped configuration, the frame element (14) (at least partially) and the bulge (5) being arranged radially within the step (18).
7. Method for producing a hydraulic directional valve (1) according to one of the preceding claims having the following method steps:

   • insertion of the filter element (13) into the groove (9), and

   • formation of at least one axial bulge (5) on at least one of the side walls (4), which at least one axial bulge (5) extends in the direction of the frame element (14) and acts on the frame element (14) in a positive and/or nonpositive manner.
8. Method according to Claim 7, characterized in that the bulge (5) is formed by means of a calking process.
9. Method according to Claim 7, characterized in that the bulge (5) is formed by means of a stamping process or annular stamping process.
10. Method according to Claim 7, characterized in that first of all the filter element (13) is inserted into the groove (9) and subsequently the bulge (5) is formed.

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