WO2017148584A1

WO2017148584A1 - Hydraulic valve clearance compensation element for a valve gear of an internal combustion engine, corresponding valve gear, and method for operating a valve gear

Info

Publication number: WO2017148584A1
Application number: PCT/EP2017/000275
Authority: WO
Inventors: Andreas Schlinke; Andreas Dietz
Original assignee: Audi Ag
Priority date: 2016-03-02
Filing date: 2017-03-01
Publication date: 2017-09-08
Also published as: DE102016002513B4; DE102016002513A1

Abstract

The invention relates to a hydraulic valve clearance compensation element (1) for a valve gear of an internal combustion engine, which valve clearance compensation element (1) has a housing (2) with a housing bottom (3) and a pressure piston (5) which is arranged linearly movably in the housing (2), protrudes out of the housing (2), in which there is a storage chamber (9) for a fluid, and which, together with the housing (2), encloses a pressure chamber (16) for the fluid, which pressure chamber (16) can be flow-connected to the storage chamber (9) by way of a non-return valve (17), wherein the storage chamber (9) is flow-connected via a fluid connection (10) to a fluid connector (11) of the valve clearance compensation element (1), wherein a clearance compensation spring (24) is arranged in the pressure chamber (16), which clearance compensation spring (24) acts on one side on the housing (2) and on the other side on the pressure piston (5), and wherein the pressure piston (5) has a bearing surface (7) for a drag lever of the valve gear, which bearing surface (7) is penetrated by a passage recess (8) for the fluid. A control valve (25) is provided here which opens a flow connection between the storage chamber (9) and the passage recess (8) in a first switching position and interrupts it completely in a second switching position. Furthermore, the invention relates to a valve gear for an internal combustion engine and to a method for operating a valve gear.

Description

The invention relates to a hydraulic valve clearance compensation element for a valve train of an internal combustion engine, which has a housing with a housing bottom and a pressure piston which protrudes linearly from the housing in the housing, in the one

Reservoir for a fluid is present and the one together with the housing via a check valve with the reservoir

fluid communicable pressure space for the fluid, wherein the reservoir via a fluid connection with a fluid port of the

Valve play compensation element is fluidly connected, wherein in the

Pressure chamber is arranged a clearance compensating spring, which acts on the one hand on the housing and on the other hand on the pressure piston, and wherein the pressure piston has a bearing surface for a finger lever of the valve train, which is penetrated by a Durchtrittsausnehmung for the fluid. The invention further relates to a valve train for an internal combustion engine and to a method for operating a valve train of a

Internal combustion engine.

The hydraulic valve clearance compensation element is a component of the valve drive or the internal combustion engine. It forms a pivot bearing or a bearing point for a drag lever of the valve train, in particular a roller rocker. For example, the drag lever on the one hand on a bearing counter element, via which it is connected to the valve lash adjuster, in particular rests on this or its bearing surface. The bearing surface is, for example, partially spherical surface-shaped, in particular hemispherical surface-shaped. The bearing counter element is preferred for at least partial absorption

CONFIRMATION COPY the bearing surface formed. In particular, it has a shape adapted to the contour of the bearing surface. In addition to the counter bearing element of the drag lever has a contact point at which it is in operative connection with a gas exchange valve of the valve train, in particular an inlet valve or an outlet valve, or at least in

Active compound can be brought.

For example, it is provided that the drag lever between the bearing counter element and the contact point is periodically subjected to force by a cam of the valve train. Because the drag lever on the

Valve play compensation element is rotatably mounted, causes this

Applying force an actuation of the gas exchange valve. The

hydraulic valve clearance compensation element is intended to compensate for a game of the valve train, in particular the drag lever, for example, a game occurring as a result of wear, thermal expansion or manufacturing tolerances, automatically.

From the prior art, for example, the document US 4,840,153 is known. This also concerns a hydraulic

Lash adjuster.

It is an object of the invention to provide a hydraulic valve clearance compensation element for a valve train of an internal combustion engine, which has advantages over known valve clearance compensation elements, in particular a demand-based lubrication of the bearing between the valve lash adjuster and rocker arm allows.

This is inventively with a hydraulic

Valve clearance compensation element achieved with the features of claim 1. In this case, a control valve is provided which in a first switching position a Flow connection between the pantry and the

Durchtnttsausnehmung releases and in a second switching position

completely interrupts. The valve clearance compensation element has the housing and the pressure piston. The pressure piston is arranged linearly displaceable in the housing and protrudes at least partially out of the housing. At the protruding from the housing portion of the pressure piston, the bearing surface is provided, on which the drag lever is mounted or can be stored. The bearing surface is for example teilkugelflächenförmig, for example, hemispherical surface. The

Bearing surface is penetrated by the passage recess through which the fluid, such as lubricant or the like, the bearing point can be fed. For example, the storage area is centered by the

Passage recess penetrated. On its side facing away from the bearing surface, the passage opening opens into the reservoir for the fluid. The storage space is formed in the pressure piston.

The pressure piston defines together with the housing the pressure chamber, which via the check valve with the reservoir

is strömungsverbindbar. This means that the flow connection between the reservoir and the pressure chamber from the check valve either closed, in particular completely closed, or at least partially, in particular completely, is released. Preferably, the check valve allows a flow between the reservoir and the pressure chamber only in one direction, namely from the reservoir in the direction of the pressure chamber. A fluid flow from the pressure chamber in the direction of the storage space, however, is prevented by the check valve. However, it can also be provided that the check valve for different flow directions different

Sets flow cross-sections to always allow a fluid exchange between the reservoir and the pressure chamber. It is preferably provided that in a fluid flow from the reservoir into the pressure chamber, the check valve a larger

Durchströmungsquerschnitt and thus allows a larger mass flow of the fluid from the reservoir into the pressure chamber than at a

Fluid flow from the pressure chamber into the storage room.

The reservoir is fluidly connected via the fluid connection with the fluid connection of the valve lash adjuster, in particular

permanently connected to the flow. This means that the fluid can be supplied to the storage space via the fluid connection and the fluid connection, in particular from a fluid source, for example one

Fluid delivery device, preferably a pump. For example, the fluid connection to a fluid circuit, in particular one

Lubricant circuit connected to the valve train. The supply of the fluid via the fluid port is provided because the fluid can escape through the passage recess from the lash adjuster and is subsequently used for lubrication of the bearing.

To compensate for the valve clearance the play compensation spring is provided. This engages on the one hand on the housing and on the other hand on the

Pressure piston on. It preferably rests on its side facing away from the pressure piston on the housing bottom of the housing. The

Play compensation spring is designed for example as a compression spring which causes a directed away from the housing bottom spring force on the pressure piston. The play compensation spring urges the pressure piston in the direction away from the housing bottom direction. Preferably, the pressure piston lies with respect to its longitudinal central axis in the circumferential direction continuously close to the housing, so that the pressure chamber of the housing is limited fluid-tight together with the pressure piston. This means that the pressure chamber only over the

Check valve fluid from the reservoir can be fed. Alternatively, however, it can also be provided that the pressure piston is arranged in the housing such that a small leakage flow of the fluid between the housing and the pressure piston can escape from the pressure chamber.

The check valve of the lash adjuster points

For example, a check valve element and a check valve seat, wherein the check valve element is urged by a check valve spring in the direction of the check valve seat. It can

be provided that the check valve spring on their the

Non-return valve element side facing away from a pot-shaped

Supporting member supported, which has a retaining collar over which the

Play compensation spring acts on the pressure piston.

In this way, the check valve can be realized extremely space-saving. For example, the check valve spring is supported on a floor in the interior of the pot-shaped holding element. Of the

Retaining collar protrudes on the side facing away from the bottom of the retaining element in the radial direction to the outside. He is on the one hand to the pressure piston. On the other hand, the play compensation spring attacks him. Accordingly, the retaining collar and thus the retaining element is urged by the play compensation spring in the direction of the pressure piston or to the pressure piston. It can be provided that the pressure piston is multi-part and has a bearing surface exhibiting the support member and the check valve exhibiting valve member. The support member and the valve member may be fixed or rigidly connected to each other, for example

non-positively and / or cohesively. For example, it is provided that the support part has an end face facing the valve part, which abuts against an end face of the valve part facing the support part. The bearing surfaces are preferably aligned with each other, so they have the same dimensions. Of course, it can also be provided that the valve member engages in the support member, in particular in this

pressed in, or vice versa.

This results in the following function of the valve clearance compensation element: If the valve clearance compensation element is not or only slightly force-loaded by the drag lever, so the force exerted by the play compensation spring on the pressure piston spring force is greater than that introduced by the drag lever on the bearing surface in the pressure piston force, so urges the Backlash spring the pressure piston in the direction away from the housing bottom direction, so that the volume of the pressure chamber

increased. Accordingly, a fluid flow from the reservoir occurs in the direction of the pressure chamber, so that the check valve opens and the flow connection between the reservoir and the pressure chamber releases. If, in contrast, the valve clearance compensation element is acted upon by the drag lever with a greater force, in particular a force which is greater than the spring force caused by the play compensation spring, a force acting on the pressure piston acts in the direction of the housing bottom. This would be a reduction of the volume of the pressure chamber and, correspondingly, a fluid flow from the pressure chamber in the direction of Pantry occur. Consequently, the check valve interrupts the

Flow connection between the pressure chamber and the reservoir, so that the volume of the pressure chamber - assuming an incompressible fluid - is kept constant. Accordingly, the of the

Drag lever on the valve play compensation element force applied the pressure piston is not or at most slightly and / or with less

Shift the speed towards the bottom of the housing.

The above-mentioned supplying the fluid to the bearing,

especially for their lubrication and / or cooling, is not in every

Operating range of the internal combustion engine necessary, but causes a high fluid mass flow, which must be supplied to the valve clearance compensation element or implemented in the fluid circuit. For this reason, the control valve is provided, by means of which the

Flow connection between the pantry and the

Durchtrittsausnehmung can be interrupted. Specifically, in the first switching position, the flow connection is at least partially, in particular completely, released and completely interrupted in the second switching position. In the second switching position, therefore, no more fluid can escape from the storage space in the direction of the passage opening or flow through the passage opening. In this way, the fluid requirement of the valve lash adjuster and thus of the valve train in at least some operating ranges of

Internal combustion engine can be significantly reduced.

In a further embodiment of the invention it is provided that the control valve has a displaceable in the pressure piston, in particular linearly displaceable, control valve member and a control valve seat, wherein the control valve seat of the pressure piston or one in the

Arranged pressure piston, in particular in the pressure piston pressed-in, insert part is formed. The control valve has as essential components the control valve element and the control valve seat. Is the control valve member to the control valve seat, so is the flow connection between the reservoir and the

Through opening completely interrupted. Is that against

Control valve element spaced from the control valve seat, the flow connection is at least partially released. The control valve seat is located, for example, on the pressure piston itself or is formed by it. However, it can also be provided that the control valve seat is provided on the insertion part, which in the

Pressure piston is present. For example, the insert is pressed into the pressure piston, so it is non-positively connected thereto.

The control valve element may basically have any shape. For example, it is spherical. With such a shape, a small pressure loss is realized with open control valve.

Preferably, the control valve element in the radial direction is continuously spaced from an inner periphery of the pressure piston, so it is not or at least not on opposite sides of this at.

Of course, it can also be provided that the

Control valve element in the circumferential direction at least partially applied to the pressure piston. In such an embodiment, the

Control valve element have at least one flow channel, which preferably from the control valve element and the pressure piston

or whose inner circumference is limited together.

A preferred further embodiment of the invention provides that the control valve element is mounted on the pressure piston via a control valve spring, wherein the control valve spring, the control valve element away from the control valve seat and in the direction of the reservoir or in this in essence. The control valve spring engages on the one hand on the

Control valve element and on the other hand to the pressure piston.

For example, the control valve spring is supported on a wall of the pressure piston opposite the bearing surface. Preferably, the control valve spring surrounds the side facing away from the bearing surface of the

Passage recess in the circumferential direction with respect to the longitudinal center axis of the pressure piston at least partially, in particular completely. The control valve spring urges the control valve element away from the bearing surface and thus away from the control valve seat, ie in particular in the direction of the reservoir or even into it.

In the context of a further embodiment of the invention, it is provided that the control valve is designed as a pressure-controlled valve, wherein the control valve is designed such that it is at a smaller first

Fluid pressure in the reservoir the flow connection between the

Reservoir and the passage opening releases and interrupts at a larger second fluid pressure. The switching position or the switching state of the control valve is thus dependent on that in the

Reservoir fluid pressure present. The control valve or its control valve spring is designed for this purpose that the

Fluid communication is present as long as the fluid pressure in the reservoir corresponds to the first fluid pressure or at least smaller than the second fluid pressure, which is greater than the first fluid pressure. If, on the other hand, the fluid pressure exceeds or exceeds the first fluid pressure or if it exceeds the second fluid pressure, then the control valve interrupts the flow connection.

If, in the context of this description of the fluid pressure in the

Reservoir is mentioned, so an absolute pressure can be meant. However, under the fluid pressure, a pressure is preferred relative to a further pressure understood, ie a relative pressure with respect to the further pressure. The further pressure is for example the pressure in the passage or an ambient pressure. For example, it is provided here that the control valve is fully opened as long as the fluid pressure is less than or equal to the first fluid pressure. Likewise, the control valve is fully closed as soon as the

Fluid pressure equal to or exceeds the second fluid pressure. On the other hand, if there is a fluid pressure which is greater than the first fluid pressure and less than the second fluid pressure, then the control valve can have a

Take switching position in which the flow connection between the reservoir and the passage recess is only partially released, ie with a smaller flow area than when fully open control valve.

A further preferred embodiment of the invention provides that the control valve seat at a relative to a longitudinal center axis of the

Pressure piston circumferential wall projection is present. The wall projection is designed circumferentially in the circumferential direction with respect to the longitudinal central axis, so it is in the circumferential direction without interruption and surrounds the entire circumference of the control valve seat. The wall projection can

Part of the plunger or be attached to this. In the former case, it is preferably formed in one piece and / or the same material with the pressure piston. On the other hand, if the wall projection is formed separately from the pressure piston, then it can be subsequently inserted into it.

For example, this is the wall projection part of the insert or is formed by this. In such a variant, the wall projection may be materialuniformly with the pressure piston, that is to say consist of a different material than this. In addition, the Wall projection usually not integrally formed with the pressure piston.

Within the scope of a preferred embodiment of the invention

provided that the wall projection is made by forming the pressure piston, in particular by forming a bead. In which

Forming is a side wall of the pressure piston in the direction of

Reservoir formed, so usually in the radial direction with respect to the longitudinal center axis of the pressure piston to the inside. For example, in this case, the bead is configured on an outer circumference of the pressure piston, so that the inner circumference for forming the wall projection in

Direction of the storage space, ie in the radial direction inward, arches. The wall projection is in other words in the form of a curvature. A development of the invention provides that the pantry

spaced from the control valve and / or to the check valve has a constriction. The constriction is to be understood as a reduction of the cross section with respect to the longitudinal center axis. On both sides of the constriction - seen in the axial direction - the reservoir has a larger cross-section than in the region of the constriction. For example, the fluid connection opens between the fluid port and the

Storage space in the constriction, thus penetrating a wall of the pressure piston in the region of the constriction. The constriction may analogously to the above statements to the wall projection by forming the pressure piston, in particular by forming a bead, be prepared. This means that an outer circumference of the pressure piston in the region of the constriction of the housing

is present at a distance, while it rests on both sides of the constriction respectively on the housing, in particular lies tightly. Using the constriction can insofar as the fluid connection between the fluid connection and the storage space can be produced in a simple manner, wherein the

Fluid connection in the radial direction on the outside of a

Inner peripheral surface of the housing and is limited in the radial direction on the inside by an outer peripheral surface of the pressure piston.

It can be provided that the constriction has internal dimensions which are larger than the internal dimensions of the control valve seat. The reduction in cross-section is thus not as pronounced in the region of the constriction as in the region of the control valve seat. Additionally or alternatively, it can be provided that the inner dimensions of the constriction are greater than dimensions of the control valve element, in particular in a direction perpendicular to the longitudinal center axis, and / or that the

Inner dimensions of the control valve seat are smaller than the dimensions of the control valve element.

Due to the larger inner dimensions of the constriction with respect to the dimensions of the control valve element, it is ensured that the fluid can always reliably flow into the reservoir, in particular if the fluid connection originating from the fluid connection has flow over the reservoir

Constriction leads into the storeroom. By with respect to the dimensions of the control valve member smaller inner dimensions of the control valve seat is a reliable interrupting the

Flow connection between the pantry and the

Durchtrittsausnehmung ensured.

Finally, it can be provided within the scope of a further embodiment of the invention that a guide element for the control valve element is arranged in the pressure piston. The guide element can

basically be configured arbitrarily. For example, it does that Control valve element in the axial direction, so allows only a shift of the control valve member in the axial direction. However, it may also be provided to limit a displacement of the control valve element in the direction away from the control valve seat, so that it as

End stop for the control valve element is used.

The invention further relates to a valve train for an internal combustion engine, with a hydraulic valve clearance compensation element, in particular a valve clearance compensation element according to the above. On the advantages of such an embodiment of the valve train or the valve train or the valve clearance compensation element has already been noted. Both the valve train and the

Valve lash adjuster can according to the above

Be further developed versions so that reference is made to this extent.

The invention further relates to a method for operating a

Valve train of an internal combustion engine with a hydraulic

Valve lash adjuster, in particular with a hydraulic

Valve lash adjuster according to the preceding embodiments, wherein the hydraulic valve lash adjuster a housing with a

Has a housing bottom and a linearly displaceable in the housing, protruding from the housing pressure piston, in which a

Reservoir for a fluid is present and the common with the housing via a check valve with the pantry

Valve play compensation element is fluidly connected, wherein in the

Pressure chamber a clearance compensation spring is arranged, which acts on the one hand on the housing and on the other hand on the pressure piston, and wherein the Pressure piston has a bearing surface for a cam follower of the valve train, which is penetrated by a Durchtrittsausnehmung for the fluid.

In this case, a control valve is provided, which is displaced into a specific switching position, which is selected from at least a first switching position and a second switching position, wherein in the first switching position, a flow connection between the reservoir and the

Passage opening released and completely interrupted in the second switching position. Again, the above

Remarks pointed out, according to which the valve train, the

Valve clearance compensation element and / or the method can be developed.

A preferred embodiment of the invention provides that the

Control valve is designed as a pressure-controlled valve, wherein the

Control valve at a smaller first fluid pressure in the reservoir, the flow connection between the reservoir and the

Passage recess releases and interrupts at a larger second fluid pressure, and wherein the fluid pressure in the reservoir by adjusting a voltage applied to the fluid port supply pressure is set to a certain fluid pressure which is selected from at least the first fluid pressure and the second fluid pressure.

This has already been mentioned before. Setting the

Supply pressure, for example, by adjusting a pressure in the fluid circuit of the valve train or the

Internal combustion engine, to which the fluid connection of the

Valve clearance compensation element is connected. By adjusting the supply pressure to the respective fluid pressure, the desired switching position of the control valve can be adjusted so that the Flow connection between the reservoir and the passage recess is either released or completely interrupted. The invention will be explained in more detail with reference to the embodiments illustrated in the drawings, without any limitation of the invention. Showing:

Figure 1 is a hydraulic valve clearance compensation element for a

Valve gear of an internal combustion engine, wherein a control valve is present in a first switching position, and

2 shows the valve clearance compensation element, wherein the control valve is present in a second switching position.

1 shows a schematic sectional view of a hydraulic valve clearance compensation element 1, as it can be used for example for a valve train of an internal combustion engine. The

Valve clearance compensation element 1 has a housing 2 with a housing bottom 3 and is in the longitudinal section shown here with respect to a longitudinal central axis 4 is substantially U-shaped. In addition to the housing 2, the valve lash adjuster 1 has a pressure piston 5, which is arranged to be linearly displaceable in the housing 2, in particular in the axial direction with respect to the longitudinal central axis 4.

The pressure piston 5 projects in regions out of the housing 2, namely on the side facing away from the housing bottom 3. For this purpose, the

Housing 2 a corresponding opening 6. In the outside of the housing 2 arranged region of the pressure piston 5, a bearing surface 7 is provided. The bearing surface 7 serves for supporting or rotatable bearings of a rocker arm, not shown here

Valve train. The bearing surface 7 forms a bearing point for the extent

Cam followers. It is penetrated by a passage recess 8, through which a fluid can be discharged from the pressure piston 5.

In the pressure piston 5, a reservoir for the fluid is provided. The storage space 9 is in fluid communication with a fluid connection 11 of the valve clearance compensation element 1 via a fluid connection 10. The fluid is made available to the valve clearance compensation element 1 at the fluid connection 11, for example by means of a fluid source. Preferably, the fluid port 11 to a fluid circuit of the valve train or the

Internal combustion engine connected.

The fluid connection 10 extends at least in regions between an inner circumference 12 of the housing 2 and an outer circumference 13 of the

Pressure piston 5. To form the fluid connection 10, the

Reservoir 9, for example, a constriction 14, which may be made by forming a bead. In the region of the constriction 14, a flow channel 15 opens into the pressure piston 5 or is formed in a wall of the pressure piston 5. On the

Flow channel 15, the reservoir 9 is fluidly connected to the fluid port 11. The flow channel 15 in this case represents a part of the fluid connection 10. The pressure piston 5 is limited together with the housing 2 and

in particular the housing bottom 3 a pressure chamber 16 for the fluid. The pressure chamber 16 is connected via a check valve 17 to the reservoir 9 fluidly connected. This means that the storage space 9 and the pressure chamber 16 with open check valve 17 with each other in

Flow connection, but this flow connection at closed check valve 17 is interrupted. The check valve 7 has a check valve element 18, a check valve seat 19 and a check valve spring 20. The check valve element 18 is, for example, spherical.

The check valve seat 19 is located on the pressure piston 5

or is trained by this. The check valve spring 20 engages on the one hand on the check valve element 18 and on the other hand on a cup-shaped retaining element 21. In particular, lies the

Check valve spring 20 with its end facing away from the check valve 18 at a bottom 22 of the support member 21 at. The holding element 21 has a retaining collar 23, which extends in the radial direction to the outside. In the pressure chamber 16, a clearance compensation spring 24 is arranged. This relies on the one hand on the housing 2, in particular on the

Housing bottom 3, and on the other hand on the pressure piston 5 from.

For example, it engages on the retaining collar 23 on the pressure piston 5. Thus, the retaining collar 23 rests on the one hand on the pressure piston 5 and on the other hand on the play compensation spring 24.

The valve clearance compensation element 1 further has a control valve 25, by means of which the flow connection between the reservoir 9 and the passage recess 8 can be selectively interrupted or released. The control valve 25 has a control valve element 26, a control valve seat 27 and a control valve spring 28. Die

Control valve spring 28 urges the control valve member 26 of the

Control valve seat 27 continues, in particular in the direction of the storage space 9. The control valve element 26 is in principle on the storage space 9 facing side of the control valve seat 27 before. The control valve 25 is designed as a pressure-controlled valve. The

Control valve 25 and its control valve spring 28 is thus designed such that the control valve 25 at a first fluid pressure in the reservoir 9, the flow connection between the reservoir 9 and the passage opening 8 releases and interrupts at a second fluid pressure. The second fluid pressure is preferably greater than the first fluid pressure. In the switching position of the control valve 25 shown here, the flow connection is released, so that fluid according to the arrows 29 and 30 flow through the control valve 25 and from the

Passage recess 8 can escape. Accordingly lies in the

Reservoir 9, a fluid pressure before, which corresponds to the first fluid pressure.

To provide reliable guidance of the control valve element 26 in the

To achieve the pressure piston 5, a guide member 31 may be provided. This can for example cause a longitudinal guide of the control valve element 26 and / or serve as an end stop in the axial direction with respect to the longitudinal central axis 4. In the embodiment shown here, the control valve seat 27 is formed by the pressure piston 5 and the wall itself. He is doing on a wall projection 32, which is prepared by forming the pressure piston 5, in particular by forming a bead 33 on the pressure piston 5. The wall projection 32 is in axial

Direction spaced from the constriction 14 before. It is indicated that the control valve element 26 has a diameter D or at least in the radial direction dimensions D. Also in the radial direction, the control valve seat 27 has a smallest diameter di or smallest dimensions in the radial direction di on, while the constriction 14th has a smallest diameter d ₂ and smallest dimensions 62 in the radial direction. In this case, it is preferable that di <D <62.

The pressure piston 5 is preferably designed in several parts and has this for a bearing surface 7 exhibiting support member 34 and a

Non-return valve 17 exhibiting valve member 35. The support member 34 and the valve member 35 may be attached to each other, in particular non-positively and / or materially. Of course, however, a one-piece design of the pressure piston 5 may be provided.

FIG. 2 shows the valve play compensation element 1 in a second switching position of the control valve 25. Reference is made in full to the above explanations. It becomes clear that now that

Control valve element 26 tightly against the control valve seat 27 is applied, so that the flow connection between the reservoir 9 and the

Passage recess 8 is interrupted. This is the

Control valve element 26, starting from the previously described with reference to Figure 1 switching position in the direction of arrow 36 in the direction of the control valve seat 27 and the Durchtrittsausnehmung 8 moves. This switching position is according to the above embodiments preferably at the second fluid pressure, which is greater than the first fluid pressure at which the control valve 25, the flow connection between the reservoir 9 and the passage opening 8 releases. With the help of the valve lash adjuster 1 described can be a simple way a need-based fluid supply of

Bearing to be ensured at which the drag lever engages the lash adjuster element 1. As a result, the fluid consumption of the valve train can be significantly reduced.

Claims

claims

1. Hydraulic valve clearance compensation element (1) for a valve drive of an internal combustion engine, which has a housing (2) with a housing bottom (3) and one in the housing (2) arranged linearly displaceable, from the housing (2) outstanding pressure piston (5), in the one

Supply chamber (9) is present for a fluid and a common with the housing (2) via a check valve (17) with the reservoir (9)

the reservoir (9) via a fluid connection (10) with a fluid port (11) of the lash adjuster (1) is fluidly connected, wherein in the pressure chamber (16) has a play compensation spring (24) is arranged , which acts on the one hand on the housing (2) and on the other hand on the pressure piston (5), and wherein the pressure piston (5) has a bearing surface (7) for a finger lever of the valve train, which penetrated by a Durchtrittsausnehmung (8) for the fluid characterized by a control valve (25) which in a first switching position, a flow connection between the reservoir (9) and the passage opening (8) releases and completely interrupts in a second switching position.

2. Hydraulic valve clearance compensation element according to claim 1,

characterized in that the control valve (25) is in the

Pressure piston (5) displaceable, in particular linearly displaceable,

Control valve member (26) and a control valve seat (27), wherein the control valve seat (27) of the pressure piston (5) or one in the

Pressure piston (5) arranged, in particular in the pressure piston (5) pressed, insert part is formed.

3. Hydraulic valve clearance compensation element according to one of

previous claims, characterized in that the Control valve element (26) via a control valve spring (28) on the

Pressure piston (5) is mounted, wherein the control valve spring (28) the

Control valve member (26) from the control valve seat (27) away and in the direction of the storage space (9) or pushes into it.

4. Hydraulic valve clearance compensation element according to one of the preceding claims, characterized in that the

Control valve (25) is designed as a pressure-controlled valve, wherein the control valve (25) is designed such that it at a smaller first fluid pressure in the reservoir (9) the flow connection between the reservoir (9) and the passage recess (8) releases and at a larger second fluid pressure interrupts.

5. Hydraulic valve clearance compensation element according to one of the preceding claims, characterized in that the

Control valve seat (27) on a relative to a longitudinal central axis (4) of the pressure piston (5) encircling wall projection (32) is present.

6. Hydraulic valve clearance compensation element according to one of the preceding claims, characterized in that the

Reservoir (9) spaced from the control valve seat (27) and / or to the check valve (17) has a constriction (14).

7. Hydraulic valve clearance compensation element according to one of the preceding claims, characterized in that in the

Pressure piston (5) a guide element (31) for the control valve element (26) is arranged.

8. Valve drive for an internal combustion engine, with a hydraulic valve clearance compensation element (1), in particular a Valve clearance compensation element (1) according to one or more of

The preceding claims, comprising a housing (2) with a housing bottom (3) and a in the housing (2) arranged linearly displaceable, from the housing (2) protruding plunger (5), in which a

Reservoir (9) is present for a fluid and the common with the housing

(2) one via a check valve (17) with the reservoir (9)

9. A method for operating a valve train of an internal combustion engine with a hydraulic valve clearance compensation element (1), in particular with a hydraulic valve clearance compensation element (1) according to one or more of the preceding claims, wherein the hydraulic

Valve clearance compensation element (1) a housing (2) with a housing bottom

(3) and one in the housing (2) arranged linearly displaceable, from the housing (2) protruding plunger (5), in which a

flow-connected pressure chamber (16) for the fluid, wherein the storage space (9) via a fluid connection (10) with a fluid port (11) of the lash adjuster (1) is fluidly connected, wherein the pressure chamber (16) a clearance compensation spring (24) is arranged, on the one hand on the housing (2) and on the other hand on the pressure piston (5) engages, and wherein the pressure piston (5) has a bearing surface (7) for a drag lever of the valve train , which is penetrated by a through-passage (8) for the fluid, characterized by a control valve (25) which is displaced into a specific switching position, which is selected from at least a first switching position and a second switching position, wherein in the first switching position, a flow connection between the storage space (9) and the passage opening (8) released and completely interrupted in the second switching position.

10. The method according to claim 9, characterized in that the control valve (25) is designed as a pressure-controlled valve, wherein the control valve (25) at a smaller ersteh fluid pressure in the reservoir (9), the flow connection between the reservoir (9) and the

Passage recess (8) releases and at a larger second

Fluid pressure interrupts, and wherein the fluid pressure in the reservoir (9) by adjusting a voltage applied to the fluid port (11)

Supply pressure is set to a certain fluid pressure, at least from the first fluid pressure and the second fluid pressure

is selected.