DE102012218406B4 - Central valve for a camshaft adjuster - Google Patents

Abstract

Central valve for a camshaft adjuster of a vehicle with: - a spring-loaded control piston (1), which is displaceably guided in a control sleeve (2), and - an actuating surface (19), which is provided for the installation of an actuator (21) fixed to the vehicle, which is used for an actuation moves the control piston (1) in the control sleeve (2), characterized in that a spring-assisted locking mechanism (20) and a displaceable pressure piece (3) are provided on the central valve, wherein - the spring-assisted locking mechanism (20) has one or more locking parts (10), which is spring-assisted by a first actuation of the actuator (21) and a resulting displacement of the pressure piece (3) from a standby position into the pressure piece (3) with the control piston (1) in the direction of actuation of the actuator (21) connecting blocking position are movable; and - the spring-assisted blocking mechanism (20) in the blocking position connects the pressure piece (3) in the actuating direction (G) of the actuator (21) with the control piston (1) in terms of movement technology and at the same time presses against the actuator (21) with the actuating surface (19) , The actuating surface being provided on the pressure piece (3) and at least one conical clamping surface (14) being provided on the pressure piece (3) and / or the control piston (1); and - the spring force-assisted blocking mechanism (20) is directed with its spring force in such a way that the blocking parts (10) are urged against the conical clamping surface (14) in the blocking position.

Description

The invention relates to a central valve for a camshaft adjuster with the features of the preamble of claim 1.

Camshaft adjusters are driven via a chain or belt drive by the crankshaft of an internal combustion engine and serve to adjust the opening and closing times of the gas exchange valves of the internal combustion engine. By adjusting the opening and closing times of the gas exchange valves, the internal combustion engine can be operated optimally in terms of fuel consumption and performance, which is an important criterion in modern motor vehicles, in particular due to the rising fuel costs and environmental requirements. The camshaft adjuster itself has a stator which can be driven by the crankshaft, and a rotor which can be connected in a rotationally fixed manner to a camshaft controlling the gas exchange valves.

The stator is cup-shaped and provided with radially inwardly projecting projections which divide an existing between the stator and the rotor annulus in several working chambers. Further, a plurality of blades are provided on the rotor, which project radially outward from the rotor and subdivide the working chambers into two oppositely acting pressure chambers. The pressure chambers can be acted upon via a central valve with a pressure medium, which has a plurality of passage openings and control edges and can be axially displaced via an actuator. Depending on the position of the central valve, the pressure chambers are then subjected in groups with pressure medium and discharged the pressure medium from the respective oppositely acting pressure chambers in a pressure medium reservoir. The central valve itself is spring-loaded and has a control piston in a displaceably guided control piston, against which the actuator.

A problem of such a camshaft adjuster is that the actuator can never be placed so precisely in front of the central valve due to manufacturing tolerances that the actuator rests in the home position without play on the control piston of the central valve. The position of the actuator to the central valve is determined by a relatively long tolerance chain, which starts at the central valve, passes over the cylinder head of the internal combustion engine and ends at the actuator. In this case, the tolerance chain includes a plurality of individual components and attachment points, the manufacturing inaccuracies eventually lead in total to the inaccurate positioning of the actuator to the central valve.

From the EP 1 485 579 B1 a camshaft adjuster is already known, in which the actuator has a larger stroke compared to the control piston, so that, as a result, smaller air gaps between the control piston and the actuator can be realized with a low production cost. Despite this smaller air gap, the positioning of the actuator to the control piston is also in this solution depending on the manufacturing inaccuracies, ie of the tolerance chain between the control piston and the actuator.

From the JP 2011-247 346 A a device is known, which relates to the compensation of an axial clearance between a control piston and an electromagnet. A compensating member is slidably disposed on the control piston end facing the push rod; the axial length of the push rod including balancing member is referred to as effective length. The compensation mechanism is designed such that the compensation element can only be displaced in one direction. Thus, a shortening of the effective length is possible, an extension, however, not possible.

The object of the invention is to provide a central valve for a camshaft adjuster, in which the actuator is always applied gap-free regardless of the manufacturing inaccuracies in the tolerance chain described above on the control piston.

According to the invention a central valve with the features of claim 1 is proposed to solve the problem. Further preferred embodiments of the invention can be found in the subclaims, the figures and the associated description.

According to the basic idea of the invention, it is proposed that a spring-assisted blocking mechanism and a displaceable pressure piece be provided on the central valve, and the actuating surface is provided on the pressure piece, and the spring-assisted blocking mechanism connects the pressure piece in the actuating direction of the actuator with the control piston and at the same time spring assisted with the actuating surface against the actuator urges. The proposed solution ensures that the actuator always rests without gaps on the central valve, regardless of the aforementioned production inaccuracies. This is made possible in particular by the actuating surface of the central valve is provided on a movable pressure piece. Furthermore, the spring-assisted blocking mechanism is of particular importance, since this allows only the play-free coupling of the control piston to the movement of the actuator by one hand, the pressure piece connects in terms of movement with the control piston and on the other hand pushes the pressure piece against the nude author. The pressure piece is thereby practically clamped between the actuator and the blocking mechanism and transmits the movement of the actuator via the blocking mechanism on the control piston.

The blocking mechanism may have in a preferred development, one or more blocking parts, which are movable by a first actuation of the actuator and thereby effected a single displacement of the pressure element spring force-assisted from a standby position in a pressure piece with the control piston in the direction of actuation of the actuator blocking position. The blocking parts thus represent the connecting parts for establishing the connection between the pressure piece and the control piston, which only during the first actuation of the actuator, d. H. in a phase in which the actuator is necessarily applied to the actuating surface, establish the connection. Since the actuator rests permanently on the actuating surface after the first actuation due to the spring load of the control piston, the first-time assumed relative orientation of the pressure piece to the actuator and thus the arrangement of the control piston to the actuator is then no longer changed and the actuator is then permanently backlash-free on the actuating surface of the pressure piece.

This can be realized in a structurally particularly simple manner by providing at least one conical clamping surface on the pressure piece and / or the control piston, and the spring force of the blocking mechanism is directed in such a way that the blocking parts are urged against the conical clamping surface in the blocking position. The conical clamping surface tapers in the direction of actuation of the actuator, so that the blocking parts take the control piston by generating corresponding clamping forces upon actuation of the actuator and thereby caused displacement of the pressure piece. Since the return movement of the control piston is effected automatically by the spring load after the end of the actuation of the actuator, and the movement of the control piston is simultaneously transmitted via the spring-assisted blocking mechanism on the pressure piece, it is sufficient that the clamping mechanism is designed only for one effective direction.

It is also proposed that the pressure piece has one or more grooves in which the blocking parts are received after the first displacement of the pressure piece. The groove forms after the first shift of the pressure piece practically a receptacle for the blocking parts, from which they are no longer moved out during further operation of the central valve. The movement of the blocking parts is automatically enforced by the spring force support of the blocking mechanism during the movement of the pressure piece, since the movement of the pressure piece is directed against the spring load of the blocking mechanism, and the blocking parts are thereby held against the direction of movement of the pressure piece and automatically into the groove slip into.

The conical clamping surface is then preferably provided in the groove, so that the blocking parts can not move laterally during the application of the clamping forces. The groove thereby not only forms the receptacle for the blocking parts, but at the same time also the clamping surface for generating the clamping force. Furthermore, the groove simultaneously forms abutment surfaces for limiting the movement of the blocking parts, whereby the clamping movement and thus also the clamping forces can be limited.

Further, at least one groove may be provided on the control piston, in which the blocking parts are receivable in the standby position. The groove on the control piston practically forms a receptacle for the blocking parts in the assembled central valve before the first actuation of the Aktautors or the first time moving the pressure piece, from which they can not escape unintentionally. The blocking parts are thus pre-positioned in the groove, so that they can be kept in a ready for the initial commissioning of the central valve standby position.

It is further proposed that the blocking mechanism comprises a sliding sleeve, which can be locked against the acting spring force of the blocking mechanism in a free space for inserting the blocking parts releasing mounting position and the blocking parts after release of the blocking spring force assisted pushes into the standby position and / or the blocking parts of the first actuation of the actuator spring force assisted pushes into the blocking position. Through the sliding sleeve, the blocking parts are initially both in the ready position and then pushed into the blocking position. Since the sliding sleeve is self-spring loaded for the automatic triggering of the movement itself, it must be blocked for inserting the blocking parts in a mounting position against the acting spring force, so that a filling opening is released for inserting the blocking parts. The blocking of the sliding sleeve can, for. B. via a suitable assembly tool, which fixes the sliding sleeve by an external engagement.

It is also proposed that the control piston has a tubular extension in which the pressure piece is guided and on the approach a pressure piece against slipping out locking ring sleeve is provided. Through the annular sleeve, the pressure piece is secured against slipping out of the control piston. Since the annular sleeve has an opening in the middle, which is smaller than the outer diameter of the pressure piece, the pressure piece can not escape, and the actuator can simultaneously abut directly against the pressure piece for actuating the central valve.

The invention will be explained in more detail with reference to a preferred embodiment. Showing:

1 an inventively designed central valve before inserting the blocking parts;

2 an inventively designed central valve during insertion of the blocking parts;

3 an inventively designed central valve with inserted blocking parts;

4 an inventively designed central valve with arranged in a standby position blocking parts;

5 an inventively designed central valve during the first actuation of an adjacent actuator; and

6 an inventively designed central valve during a subsequent actuation of an adjacent actuator.

In the 1 is an inventively designed central valve before the introduction of spherical blocking parts 10 to recognize. The central valve has a basic structure with a control piston 1 , a control sleeve 2 and a central spring 7 which can be considered as known in the art. In the control sleeve 2 are a plurality of openings 8th and 9 provided, which by moving the control piston 1 can be optionally closed, so that a pressure medium supplied to the central valve can be selectively introduced into different pressure chambers of a camshaft adjuster for adjusting a camshaft relative to a crankshaft of an internal combustion engine. The central spring 7 supports itself fixedly to the central valve and urges the control piston 1 in the direction of one in the 5 and 6 indicated actuator 21 which the control piston 1 upon actuation in the control sleeve 2 shifts.

The control piston 1 is at its projecting from the central valve free end with a tubular extension 22 provided in which a pressure piece 3 slidably guided. Further, in the tubular extension 22 a spring assisted blocking mechanism 20 provided, which a compression spring 6 , a sliding sleeve 5 and a plurality of the spherical blocking portions 10 includes. The compression spring 6 supported on the one hand in a cylindrical recess 24 of the control piston 1 and on the other hand on the sliding sleeve 5 from. The sliding sleeve 5 has on its outside a circumferential groove 18 in which an indicated assembly tool 17 engages from the outside and the sliding sleeve 5 opposite to that of the compression spring 6 exerted spring force blocked in the illustrated mounting position. In the tubular extension 22 is also an opening 23 provided, which by the blocked in the mounting position sliding sleeve 5 is released. The pressure piece 3 is mushroom-shaped and has a first paragraph 11 with a relative to the inner diameter of the tubular extension 22 smaller outer diameter and a second paragraph 12 with a relative to the inner diameter of the tubular extension 22 identical outside diameter. The paragraphs 11 and 12 are through a groove 13 with a conical towards the first paragraph 11 tapered clamping surface 14 separated from each other. The pressure piece 3 is with the second bigger paragraph 12 in the tubular extension 22 slidably guided and in turn serves as a guide for those on the first paragraph 11 guided sliding sleeve 5 , Adjacent to the opening 23 is on the inner wall 15 of the tubular extension 22 a circumferential annular groove 16 provided, which deals with the opening 23 overlaps to increase the filling cross section. Due to the smaller outside diameter of the first paragraph 11 is between the paragraph 11 and the inner wall 15 of the extension 22 an annulus formed through the opening 23 is accessible from the outside.

At the front of the extension 22 is also an annular sleeve 4 with a central opening arranged in the base area 25 provided, whose opening width is smaller than the inner diameter of the extension 22 is, so the pressure piece 3 through the ring sleeve 4 secured against slipping out.

The spring-assisted locking mechanism 20 is assembled by the blocking parts 10 in the opening 23 introduced in the direction of arrow A and then laterally in the direction of arrow B in the groove 16 slip in, as in the 2 can be seen. The sliding sleeve 5 is during the filling process by means of the assembly tool 17 blocked in the mounting position until all blocking parts 10 are arranged in the groove, as in the 3 can be seen. Subsequently, the Montagewegzeug 17 solved, whereby the sliding sleeve 5 due to the pressure spring 6 applied spring force automatically moves in the direction of arrow D, resulting in the 4 can be seen. The sliding sleeve 5 thereby comes to rest on the blocking parts 10 and forces them into a readiness position. The 4 shows the central valve with the locking mechanism in the ready position 20 how it is delivered to the vehicle manufacturer as an assembly together with a camshaft adjuster, not shown.

In the 5 is the movement sequence of the blocking mechanism 20 upon first actuation by an indicated actuator 21 to recognize. The actuator 21 is located on one of the pressure piece 3 provided actuating surface 19 which is through the opening 25 the annular sleeve 4 is released. At the first actuation of the actuator 21 becomes the pressure piece 3 laterally in the direction of the sliding sleeve 5 shifted in the direction of arrow E, causing the blocking parts 10 in the direction of arrow F in the groove 13 slip into. In a subsequent deactivation of the actuator 21 becomes the pressure piece 3 along with those in the groove 13 located blocking parts 10 through the compression spring 6 spring-assisted via the sliding sleeve 5 pushed back, with the sliding sleeve 5 directly at the blocking parts 10 abuts and also the pressure piece 3 pushed back, and so far that the pressure piece 3 with the actuating surface 19 always neatly on the nude author 21 is applied. This position is in the 6 to recognize. It can due to the spring travel of the compression spring 6 different positions of the pressure piece 3 be realized.

In a subsequent actuation of the central valve by the actuator 2 becomes the pressure piece 3 with the control piston 1 due to the gap-free installation of the actuator 21 moved immediately and without time delay. The blocking mechanism connects 20 the pressure piece 3 over the at the conical clamping surface 14 adjacent blocking parts 10 with the control piston 1 by removing the blocking parts 10 through the conical clamping surface 14 be pushed outwards and on the inner wall 15 get to the plant with a clamping force. Due to the acting clamping force of the control piston 1 finally over the blocking parts 10 taken. Because the blocking parts 10 while constantly from the sliding sleeve 5 against the conical clamping surface 14 There is no risk that the blocking parts 10 together with the pressure piece 3 before taking the control piston 1 a relative movement relative to the control piston 1 perform and the actuator movement 21 not completely on the control piston 1 is transmitted.

The compression spring 6 causes the blocking parts 10 constantly and without play on the conical clamping surface 14 abutment and the pressure piece 3 with the actuating surface 19 backlash against the actuator 21 urges. It also ensures that the movement of the pressure piece 3 due to the adjacent blocking parts 10 directly or with the least possible delay on the control piston 1 is transmitted.

As a parameter for the design of the blocking mechanism 20 stand the inclination of the clamping surface 14 , the spring force of the compression spring 6 and the shape of the blocking parts 10 to disposal.

LIST OF REFERENCE NUMBERS

1

spool

2

control sleeve

3

Pressure piece

4

ring sleeve

5

sliding sleeve

6

compression spring

7

Rear shock

8th

opening

9

opening

10

blocking part

11

First paragraph

12

Second paragraph

13

groove

14

clamping surface

15

inner wall

16

groove

17

assembly tool

18

groove

19

actuating surface

20

blocking mechanism

21

actuator

22

extension

23

opening

24

recess

Claims (6)

Central valve for a camshaft adjuster of a vehicle, comprising: - a spring-loaded control piston ( 1 ), which in a control sleeve ( 2 ) is displaceably guided, and - an actuating surface ( 19 ), which for the installation of a vehicle fixed fixed actuator ( 21 ) is provided, which upon actuation of the control piston ( 1 ) in the control sleeve ( 2 ), characterized in that at the central valve, a spring-assisted locking mechanism ( 20 ) and a displaceable pressure piece ( 3 ) are provided, wherein The spring-assisted locking mechanism ( 20 ) one or more blocking parts ( 10 ), which by a first actuation of the actuator ( 21 ) and thereby caused a one-time displacement of the pressure piece ( 3 ) spring-assisted from a standby position in a pressure piece ( 3 ) with the control piston ( 1 ) in the actuating direction of the actuator ( 21 ) connecting blocking position are movable; and - the spring-assisted locking mechanism ( 20 ) in the blocking position the pressure piece ( 3 ) in the actuating direction (G) of the actuator ( 21 ) with the control piston ( 1 ) motion-related and at the same time spring-assisted with the actuating surface ( 19 ) against the actuator ( 21 ), wherein on the pressure piece ( 3 ) the actuating surface and on the pressure piece ( 3 ) and / or the control piston ( 1 ) at least one conical clamping surface ( 14 ) are provided; and - the spring-assisted locking mechanism ( 20 ) is directed with its spring force such that the blocking parts ( 10 ) in the blocking position against the conical clamping surface ( 14 ). Central valve according to claim 1, characterized in that - the pressure piece ( 3 ) one or more grooves ( 13 ) in which (n) the blocking parts ( 10 ) after the first displacement of the pressure piece ( 3 ). Central valve according to claim 2, characterized in that - the conical clamping surface ( 14 ) in the groove ( 13 ) is provided. Central valve according to one of claims 2 to 3, characterized in that - on the control piston ( 1 ) at least one groove ( 13 ) is provided, in which the blocking parts ( 10 ) are receivable in the standby position. Central valve according to one of claims 2 to 4, characterized in that - the blocking mechanism ( 20 ) a sliding sleeve ( 5 ), which - against the acting spring force of the blocking mechanism ( 20 ) in a free space for inserting the blocking parts ( 10 ) releasable mounting position is blocked, and - the blocking parts ( 10 ) after release of the blocking, spring-force-urged into the ready position, and / or - the blocking parts ( 10 ) after the first actuation of the actuator ( 21 ) spring force assisted in the blocking position urges. Central valve according to one of the preceding claims, characterized in that - the control piston ( 1 ) a tubular extension ( 22 ), in which the pressure piece ( 3 ), and - on the extension ( 22 ) one the pressure piece ( 3 ) against slipping out annular sleeve ( 4 ) is provided.

Images