DE102012204617A1 - Control valve of camshaft adjuster used in internal combustion engine, has control piston which is secured against rotation to housing so that partial control edge at outer periphery cooperates with opening of housing - Google Patents

Abstract

The control valve (1) has a hollow cylindrical housing (3) having several openings (5). An axially movable control piston (4) is provided in the housing. The peripheral control edge (6) of the control piston is axially positioned to the opening of the housing, for controlling the hydraulic fluid flow so as to change the flow area for hydraulic fluid flow between the ports through the opening. The control piston is secured against rotation to the housing so that partial control edge (2) at outer periphery cooperates with opening.

Description

Field of the invention

The invention relates to a control valve of a camshaft adjuster.

Background of the invention

Camshaft adjusters are used in internal combustion engines to vary the timing of the combustion chamber valves in order to make the phase relation between a crankshaft and a camshaft in a defined angular range, between a maximum early and a maximum late position, variable. Adjusting the timing to the current load and speed reduces fuel consumption and emissions. For this purpose, camshaft adjuster are integrated into a drive train, via which a torque is transmitted from the crankshaft to the camshaft. This drive train may be formed for example as a belt, chain or gear drive.

In a hydraulic camshaft adjuster, the output element and the drive element form one or more pairs of mutually acting pressure chambers, which can be acted upon by hydraulic fluid. The drive element and the output element are arranged coaxially. By filling and emptying individual pressure chambers, a relative movement between the drive element and the output element is generated. The rotationally acting on between the drive element and the output element spring urges the drive element relative to the output element in an advantageous direction. This advantage direction can be the same or opposite to the direction of rotation.

One type of hydraulic phaser is the vane phaser. The vane cell adjuster comprises a stator, a rotor and a drive wheel with an external toothing. The rotor is designed as a driven element usually rotatably connected to the camshaft. The drive element includes the stator and the drive wheel. The stator and the drive wheel are rotatably connected to each other or alternatively formed integrally with each other. The rotor is coaxial with the stator and located inside the stator. The rotor and the stator are characterized by their, radially extending wings, oppositely acting oil chambers, which are acted upon by oil pressure and allow relative rotation between the stator and the rotor. The wings are either formed integrally with the rotor or the stator or arranged as "inserted wings" in designated grooves of the rotor or the stator. Furthermore, the vane cell adjusters have various sealing lids. The stator and the sealing lids are secured together via several screw connections.

Another type of hydraulic phaser is the axial piston phaser. Here, a displacement element is axially displaced via oil pressure, which generates a helical gear teeth relative rotation between a drive element and an output element.

The hydraulic camshaft phaser control valves control the flow of hydraulic fluid between the phaser and the oil pump or reservoir.

The control valve has a hollow cylindrical housing and a rotationally symmetrical control piston. Within the housing of the control valve, the control piston is arranged. The control piston is movable in the axial direction and guided by the housing. Thus, the control piston can be positioned to the housing in any axial position. The positioning is carried out by an electromagnet, which contacted with its actuating pin one end of the control piston and can move the control piston. A spring ensures the contact between the control piston and the actuating pin. By the axial positioning of the control piston, the various ports of the control valve are hydraulically connected to each other or separated from each other and can communicate with each other or not. For guiding the hydraulic fluid between the terminals are control piston and housing with openings, for. B. grooves and / or holes provided. The control piston has control edges which, together with the edges of the openings of the housing, control the flow. The control edges themselves are the edges of the respective opening, z. B. grooves, the control piston. To control the flow, the edges of the openings of the housing and the control edges are positioned to each other such that an opening of the housing with an opening of the control piston as far as possible faces and forms, over the axial positionability of the control piston, variable flow area for the hydraulic medium.

A control valve designed as a central valve is arranged coaxially to the axis of symmetry or rotation of the camshaft adjuster or the camshaft. In addition, the central valve is placed inside the camshaft adjuster, ie central valve and camshaft adjuster build on each other in the radial direction. Optionally, the camshaft can be arranged between the camshaft adjuster and the central valve. The housing of the central valve may be formed as a central screw, whereby the camshaft adjuster is braced against rotation with the camshaft. Of the Electromagnet is arranged as a central magnet largely aligned with the central valve and usually fixed to the frame, in particular on the cylinder head arranged.

Alternatively, a control valve with an electromagnet fixedly secured thereto may be disposed at any position in the hydraulic fluid gallery, outside the phaser and the camshaft, and control the flow of hydraulic fluid.

The WO 2010/015541 A1 shows a camshaft adjuster with a central valve. The central valve has two inlet ports, one coaxial with the central valve and the other with the central valve. The inlet connections are designed as bores. Next, the central valve has two working ports on the outer periphery, which face the hydraulic fluid channels to the pressure chambers. On the camshaft side facing away from the tank port is arranged to return displaced hydraulic fluid in the reservoir of the internal combustion engine.

The DE 198 17 319 A1 shows a central valve of a camshaft adjuster. The inlet connection is arranged on the outer circumference of the central valve. The inlet connection is flanked in the axial direction by the two working connections. The tank connection is located at the camshaft-facing end of the central valve and opens into a radial bore of the camshaft.

Summary of the invention

The object of the invention is to provide a control valve of a camshaft adjuster, which allows an improved control of the hydraulic camshaft adjuster.

According to the invention, this object is solved by the features of claim 1.

A control valve of a camshaft adjuster, wherein the control valve for controlling the camshaft adjuster is flowed through by the hydraulic fluid and the control valve has an inflow port, a plurality of working ports and a tank port, wherein the control valve comprises a hollow cylindrical housing having a plurality of openings and a housing movable axially in the control piston, wherein for control the hydraulic fluid flow, a control edge of the control piston is axially positionable to an opening of the housing so as to change the flow area for the hydraulic fluid flow between the terminals through the opening, solves the problem according to the invention in that the control piston is secured against rotation to the housing and on its outer periphery a Partial control edge, which cooperates with an opening of the housing.

The control edge of the control piston is formed on the outer circumference of the control piston, wherein the outer circumference of the control piston is guided by an inner circumference of the housing and thereby contact each other, wherein the inner circumference of the housing has the opening which, from the control edge of the control piston in the axial positioning of the control piston is swept over relative to the housing.

By the partial control edge of the control piston, which cooperates with an opening of the housing and the non-rotating control piston is achieved that openings can be circumferentially distributed, the openings can control the hydraulic fluid independently to different ports. As a result, space is saved and realized a compact arrangement.

In one embodiment of the invention, the rotation of the control piston to the housing is formed by means of a positive connection. Advantageously, ensures a positive fit extremely accurate, the relative angular position of the control piston and the housing to each other in each axial position of the control piston to the housing.

In a further embodiment of the invention, the control piston is acted upon by a compression spring with an axial force and formed against rotation by the compression spring. The compression spring secures contact with the actuating pin of an electromagnet. The rotation can on the one hand by the compression spring by a non-round, z. B. oval or polygonal, spring body can be achieved, which is in a complementary receptacle of the housing and / or the control piston. On the other hand, the rotation can be realized by the fixation of the spring ends, in particular angled spring ends, the compression spring respectively on the housing and on the control piston.

The partial control edge on the outer circumference of the control piston can be defined as a boundary edge of an opening or partial recess, for example a bore, a window and / or a not completely circumferential groove on the outer circumference, or by a non-circumferential web on the outer periphery. The partial control edge according to the invention is not formed completely circumferentially or not closed circumferentially on the outer circumference of the control piston. Advantageously, so concentrates the controllability of the flow of the hydraulic fluid to a discrete point in the control valve.

In an advantageous embodiment of the invention, the partial control edge is formed by a not completely circumferential web of the control piston. Advantageously, such a web engage with its circumferentially bounding edges in an axial groove of the housing and at the same time form the rotation. The web can sweep the opening of the housing with its control edge until the web, in particular completely, covers the opening, so that no or a minimum flow area for the hydraulic fluid is provided. The flow area due to the radial clearance between the control piston and housing is disregarded in this invention.

In a particularly advantageous embodiment of the invention, the web is penetrated by a passage opening in the radial direction. Advantageously, the hydraulic fluid can be passed through this passage opening. If the control piston is displaced in the axial direction, the mouth of the passage opening facing the inner circumference of the housing can be displaced outside the opening of the housing and thus the flow area for the hydraulic medium can be varied.

In a further embodiment of the invention, the partial control edge cooperates with an opening formed as a bore. The partial control edge may itself be formed by a bore, a window or a partial web. Holes of the housing can be economically introduced and have the advantage of their round shape that the flow area increases steadily and gradually with axial positioning of the control piston. The controllability is thus advantageously better controllable.

In an alternative embodiment of the invention, the partial control edge cooperates with an opening formed as a window. Windows are ideally aligned parallel or transverse to the axis of symmetry of the housing. An angled arrangement of the windows is advantageous, because thus the flow area changes continuously and gradually with axial positioning of the control piston. The controllability is thus better controllable.

In one embodiment of the invention, the opening, which cooperates with the partial control edge, directs the hydraulic fluid flow to a working port of the control valve and communicates with a lock of the camshaft adjuster. Advantageously, a more compact arrangement of a plurality of working connections, in particular a working connection for a lock, is realized in this way. In a smaller space can be accommodated in the control valve several control possibilities of the latches of the camshaft adjuster with more than one lock and more complex concepts of Verrieglungsstrategie be implemented.

In a preferred embodiment, the lock locks the phaser in the center position.

In a particularly preferred embodiment of the invention, the control valve is designed as a central valve. Advantageously, the central valve is arranged radially inside the camshaft adjuster or the camshaft. Short hydraulic paths from the central valve to the camshaft phaser result in a shortened control delay, and thus the camshaft adjuster arrangement improves the performance of the entire camshaft phasing system.

The inventive design of the control piston a variety of new connection configurations is possible, at the same time the axial space is reduced or at least is almost constant. In addition, the new connection configurations can include more functional connections in almost the same space, especially in the axial direction.

Brief description of the drawings

Embodiments of the invention are illustrated in the figures.

Show it:

1 a control valve designed as a central valve,

2 the housing insert of the central valve after 1 .

3 follow the control piston of the central valve 1 and

4 another designed as a central valve control valve with one of the control piston to 1 different control piston.

Detailed description of the drawings

1 shows a trained as a central valve control valve 1 ,

The control valve 1 has a hollow cylindrical central screw 12 , a housing insert 11 , a sleeve-shaped housing 3 , a control piston 4 , a compression spring 10 , a spring support element 17 and other components, which will not be discussed here. All of the aforementioned components are coaxial with each other and to a common axis of rotation 18 arranged, which at the same time the axis of rotation 18 a camshaft adjuster or a camshaft.

The hollow cylindrical central screw 12 is intended for non-rotatable mounting of the camshaft adjuster with the camshaft. The housing insert 11 is from an inner circumference of the central screw 12 added. The housing insert 11 has channels and openings to supply hydraulic fluid from an inlet port P of the control valve 1 to the working connections A, B, C to guide. The working ports A, B, C are at different, angularly offset positions on the outer circumference of the control valve 1 arranged. The inlet connection P is located on the thread-side end face of the control valve 1 , The tank connection is located on the end face of the control valve opposite the feed connection P. 1 ,

The control piston 4 is from a compression spring 10 subjected to force and against a circlip 19 pressed. The circlip 19 secures the axial position of the housing insert 11 and the control piston 4 inside the central screw 12 , The compression spring 10 supported on the one hand on the control piston 4 and on the other hand on the spring support 17 from. The spring support element 17 is, as is the case 3 , with the housing insert 11 firmly connected.

The control piston 4 gets over its outer circumference 7 from the case 3 guided. The housing 3 has each distributed over the circumference openings 5 . 20 . 21 . 22 on, with the openings 20 the inlet port P, the openings 21 the working connection B, the openings 22 the working connection A and the openings 5 assigned to the working port C. At the outer circumference 7 are partial, ie not completely around the outer circumference 7 circumferential or circumferentially not closed control edges 2 , These partial control edges 2 stand the opening 5 across from. The opening 5 directs the hydraulic fluid to the working port C, which in contrast to the working ports A and B, leading to the working chambers of the camshaft adjuster. The working chambers of the camshaft adjuster are known from the prior art and generate when filled with hydraulic means, the relative displacement between the camshaft and crankshaft. The working port C is assigned to a lock of the camshaft adjuster. The lock is known to lock the camshaft adjuster in its angular position in the intermediate position, ideally in the likewise known center position.

In contrast, the control piston 4 for example, a control edge 6 on which of an opening 20 faces. This control edge 6 however, is formed closed in the circumferential direction, in particular as an edge of a diameter paragraph to the outer periphery 7 , The control edge 6 also controls the flow through the openings 21 that lead to the work connection B. The partial control edge 2 however, extends only over an angular range less than 360 °. Preferably, the partial control edge 2 as non-circumferential footbridge 8th of the control piston 4 educated. The non-circumferential footbridge 8th is similar to a local dome. The openings 5 and 20 are as windows of the housing 3 formed, however, wherein the openings 21 are formed as holes.

The control piston 4 has a first pair of non-circumferential ridges 8th on which are spaced apart in the axial direction. There is also a second pair of non-rotating bars 8th , which are arranged in the same axial position as the first pair, but in a different angular position. Every pair of non-rotating bars 8th there is an opening 5 across from. All both pairs of non-rotating bars 8th have the partial control edges at the edges facing each other in the pair 2 because these are used to control the flow through the opening 5 intended. In the illustrated, unactuated position of the control piston 4 closes a not completely circumferential web 8th of each pair the respective opening 5 , The control piston 4 is to the housing 3 against rotation, whereupon in the 2 and 3 will be discussed in more detail.

Will the spool 4 shifted by an actuating pin of an electromagnet, in particular a central magnet, in its axial position, the partial control edge 2 a not completely circumferential ridge 8th the respective opening 5 compared. With progressive axial displacement of the control piston 4 is the opening 5 between the respective pair of non-circumferential webs 8th and thus also between the partial control edges 2 the pair of not completely encircling webs 8th , In this position is the maximum flow of hydraulic fluid through the opening 5 given, because the hydraulic fluid can, starting from the inlet port P through the opening 20 in the circumferential direction around the control piston 4 distribute, circumferentially flows around the first and the second pair of non-circumferential webs 8th and thus passes through the opening 5 through to port C. The control of the hydraulic fluid flow through the ports 20 . 21 and 22 knows the expert from the prior art.

2 indicates the housing insert of the central valve 1 , Good to see the circumferentially distributed and arranged in different axial planes openings 22 . 5 . 20 and 21 , The openings 22 . 5 . 20 and 21 Do not communicate peripherally over the housing insert 11 or the housing 3 with each other, but only on the flow around the here hidden control piston 4 due to its axial positioning.

The attention in 2 be on the spring suspension 15 directed. The spring suspension 15 is formed as a passage recess, for example. A bore. In addition, the spring suspension extends 15 in the housing insert 11 into it. In the spring suspension 15 engages the one, angled spring end of the compression spring 10 one.

3 indicates the control piston of the central valve 1 , Complementary to in 2 described spring suspension 15 has the spool 4 a spring suspension 13 , which as a depression of the spring system 14 is trained. At the spring system 14 finds the compression spring 10 Contact, so that the control piston 4 is acted upon in the axial direction by the spring force. In the spring suspension 13 grips the other, also angled spring end of the compression spring 10 one. In this way, an anti-rotation between the control piston 4 and housing 3 realized.

Well recognizable in 3 the two pairs of incomplete webs 8th , which are diametrically opposed as far as possible. At both ends of the control piston 4 are the same diameter of the outer circumference 7 guide surfaces 16 for the axial guidance of the control piston 4 in the case 3 , Ideally, the pairs are not completely circumferential webs 8th on its outer circumference 7 the same diameter.

To improve the flow around the non-circumferential webs 8th For example, the edges may be rounded or another cross-sectional shape may be provided instead of the largely rectangular cross-sectional shape shown here, for example an oval or drop-shaped cross-sectional shape.

4 shows another designed as a central valve control valve 1 with one of the spool 4 to 1 different control piston 4 , With the control piston shown here 4 have the not completely circumferential ridges 8th in each case one passage opening 9 on that the respective footbridge 8th completely penetrated in the radial direction. This passage opening 9 leaves in the extreme positions of the control piston 4 the hydraulic fluid from the working port C, in particular in use for a locking of the camshaft adjuster run off to the tank connection. The hydraulic fluid passes through the hollow cylindrical interior of the control piston 4 and passes through further openings at one end of the control piston 4 to a tank or reservoir. In the formation of the control piston 4 according to 1 in which the webs 8th no passage opening 9 have a drain of the hydraulic fluid from the locking mechanism is otherwise realized in the camshaft adjuster itself.

The control piston 4 in training 1 or 4 is preferably made by a primary molding process, such as injection molding, sintering or MIM, wherein to increase the accuracy of the outer periphery 7 a subsequent grinding process may be required. A produced by a forming process control piston 4 is conceivable. An adjoining grinding process to increase the accuracy of the outer circumference 7 can be provided.

LIST OF REFERENCE NUMBERS

1

control valve

2

partial control edge

3

casing

4

spool

5

Opening (for C)

6

circumferential control edge

7

outer periphery

8th

not completely circumferential bridge

9

Through opening

10

compression spring

11

housing insert

12

central screw

13

spring suspension

14

suspension system

15

spring suspension

16

guide surfaces

17

spring support

18

axis of rotation

19

circlip

20

Opening (for P)

21

Opening (for B)

22

Opening (for A)

A

working port

B

working port

C

working port

P

inflow connection

T

tank connection

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2010/015541 A1 [0010]
• DE 19817319 A1 [0011]

Claims (10)

Control valve ( 1 ) of a camshaft adjuster: - wherein the control valve ( 1 ) is flowed through by the hydraulic medium for controlling the camshaft adjuster and - the control valve ( 1 ) has an inflow port (P), a plurality of working ports (A, B, C) and a tank port (T) and the control valve ( 1 ): - a hollow cylindrical housing ( 3 ) with several openings ( 5 ), - one in the housing ( 3 ) axially movable control piston ( 4 ), - wherein for controlling the flow of hydraulic fluid, a control edge ( 6 ) of the control piston ( 4 ) to an opening ( 5 ) of the housing ( 3 ) is axially positionable so as to allow the flow area for the flow of hydraulic fluid between the ports (P, T, A, B, C) through the port (Fig. 5 ), characterized in that the control piston ( 4 ) to the housing ( 3 ) is secured against rotation and on its outer circumference ( 7 ) a partial control edge ( 2 ) provided with an opening ( 5 ) of the housing ( 3 ) cooperates. Control valve ( 1 ) according to claim 1, characterized in that the rotation of the control piston ( 4 ) to the housing ( 3 ) is formed by means of a positive connection. Control valve ( 1 ) according to claim 1 or 2, characterized in that the control piston ( 4 ) of a compression spring ( 10 ) is acted upon by an axial force and the rotation by the compression spring ( 10 ) is trained. Control valve ( 1 ) according to one of the preceding claims, characterized in that the partial control edge ( 2 ) of a not completely circumferential web ( 8th ) of the control piston ( 4 ) is trained. Control valve ( 1 ) according to claim 4, characterized in that the web ( 8th ) from a passage opening ( 9 ) are penetrated in the radial direction. Control valve ( 1 ) according to one of claims 1 to 5, characterized in that the partial control edge ( 2 ) with an opening formed as a bore ( 5 ) cooperates. Control valve ( 1 ) according to one of claims 1 to 5, characterized in that the partial control edge ( 2 ) with an opening formed as a window ( 5 ) cooperates. Control valve ( 1 ) according to claim 1, characterized in that the opening ( 5 ), with the partial control edge ( 2 ), the hydraulic fluid flow to a working port (A, B, C) passes, which communicates with a lock of the camshaft adjuster. Control valve ( 1 ) according to claim 1, characterized in that the lock locks the camshaft adjuster in the center position. Control valve ( 1 ) according to one of the preceding claims, characterized in that the control valve ( 1 ) is designed as a central valve.

Images