EP2324212B1 - Camshaft adjustment device for an internal combustion engine - Google Patents

Abstract

A device for variable adjustment of the timing of gas exchange valves of an internal combustion engine, which has a hydraulic phase shifting device, a camshaft and a pressurizing medium distributor. The phase shifting device can come into drive linkage with a crankshaft and is rigidly connected to the camshaft. A phase position of the camshaft relative to the crankshaft can be variably adjusted by the phase shifting device. The interior of the camshaft has a cavity that communicates with one or more camshaft bearings which are separate from a rotating pressurizing medium conveyor. The pressurizing medium distributor is disposed in a receiving area of the camshaft. The camshaft has an opening in the area of the pressurizing medium distributor, which communicates with the interior of the camshaft and the pressurizing medium conveyor. A pressurizing medium path is inside the camshaft, which communicates the opening and hydraulic phase shift device.

Description

Field of the invention

The invention relates to a camshaft adjusting device with a drive wheel and a driven part arranged rotatably relative thereto, the drive wheel and driven part being in operative connection via at least one pressurizable pressure chamber, and at least one regulating device being provided for regulating the pressure medium supply to the pressure chamber and the pressure fluid discharge from the pressure chamber, wherein at least one pressure medium inlet connection between the regulating device and a pressure medium supply device is designed for supplying pressure medium.

Such a camshaft adjusting device is made DE 101 03 876 A1 / US 6,553,951 B2 and US 2006/0213471 A1 known. There, a housing component drivable by the engine of an internal combustion engine and a rotor component rotatably connected to a camshaft of the engine are arranged so as to be rotatable relative to one another. For setting a relative phase rotation angle between the rotor component and the housing component, these are in operative connection via a plurality of pressure chambers, each of which is connected in a rotationally fixed manner to the rotor component by two pressure chambers which can be acted upon by pressure medium and act against each other. The pressure medium is applied to the pressure chambers via a pressure medium connection between the pressure chambers and a pressure medium pump, which promotes pressure medium from a pressure medium reservoir. The pressure medium supply to the pressure chambers and the pressure medium discharge from the pressure chambers is regulated via a control valve arranged in the pressure medium connection. For pressure medium supply, the control valve is connected via a pressure medium supply line to the pressure medium pump and the pressure medium reservoir.

With an adjustment of the relative phase rotation angle between the rotor component and the housing component, a pressure difference arises between the respectively acting in the oppositely acting pressure chambers pressure fluid pressures. As a result, the wing parts are not hydraulically clamped in the pressure chambers and perform in accordance with the force acting on the camshaft alternating torques oscillatory movements. When swinging back the wing parts against the adjustment direction, an overpressure may occur in the pressure chambers to be filled. If the excess pressure exceeds the pressure medium admission pressure prevailing in the pressure medium inlet connection, the overpressure can continue via the pressure medium connection to the control valve and via the internal connections in the control valve into the pressure medium supply line between control valve and pressure medium pump or pressure medium reservoir. In order to prevent a backflow of the pressure medium in the direction of the pressure medium pump or the pressure medium reservoir, a check valve is arranged in the pressure medium supply line.

A disadvantage of this embodiment, the fact that in an operating condition with higher prevailing in the pressure fluid system pressure medium pressure, the check valve in the forward direction at Druckmittelbeaufschlagung generates a large flow resistance in the pressure medium supply line, which leads to throttling the pressure medium supply and thereby to a deteriorated adjustment of the camshaft adjustment.

In US 2006/0213471 A1 is in the pressure medium inlet connection to a check valve in a bypass in parallel, controllable check valve provided which is opened or closed depending on the temperature of the pressure medium. At low pressure medium temperatures and high viscosity of the pressure medium, the check valve is opened. As a result, the pressure medium flows through the open shut-off valve via the bypass with lower flow resistance. If the pressure medium temperature is greater than a predetermined threshold at which the pressure medium viscosity is small, the check valve closed, whereby the bypass is locked and the pressure medium is passed through the check valve.

A disadvantage of this embodiment, the fact that the temperature-controlled opening and closing of the check valve additional control means are required, which increase the production cost.

Another disadvantage of this arrangement is the fact that at high pressure medium temperature and high pressure medium admission pressure, the shut-off valve and the bypass are closed in temperature-controlled manner. As a result, in high-speed engine operation, the pressure medium supply via the check valve at high flow resistance and throttled Druckmitteldurchfluss, whereby the dynamics of the adjustment process is significantly deteriorated.

In addition, at a pressure medium in an operating condition with low pressure medium temperature with open check valve occurring due to operation in the pressure chambers overpressure continue over the open bypass and cause a backflow of the pressure medium in the direction of the pressure medium pump or in the direction of the pressure fluid reservoir, with the result also a considerable deteriorated Verstelldynamik.

Another camshaft adjuster is in the EP 0 924 393 A2 disclosed. In the hydraulic circuit two check valves are arranged. One is located between the pressure medium pump and the control valve (directional control valve) and is intended to prevent the return or a pressure peak of the pressure medium, triggered by a counter to the adjustment acting camshaft alternating torque from the pressure chamber in the direction of the pressure medium pump. The other non-return valve bypasses the control valve, branches and opens into two pressure chambers acting congruently. The two pressure chambers are permanently supplied with pressure medium from the pressure medium pump. This check valve also prevents backflow from the two pressure chambers to the pressure medium pump, but the two pressure chambers do not have to do an adjustment task. Rather, between the two pressure chambers provided geometrically defined throttles, which can flow during the adjustment pressure medium from one chamber to the adjacent. The continuity of the rotational movement of the adjustment is improved and the influence of pressure pulsations is minimized.

Summary of the invention

The invention is therefore an object of the invention to provide a camshaft adjusting device of the aforementioned type which avoids the aforementioned disadvantages. The object is solved by the features of claim 1.

By the present invention, at least two in the pressure medium inlet connection between the regulating device and pressure medium supply means connected in parallel check valves on the one hand by a in the Druckmittelzulaufverbindung before the check valves prevailing pressure medium pressure (differential pressure) dependent backflow of the fluid from the Druckmittelzulaufverbindung in the pressure medium pump or the pressure medium reservoir in safely avoidable in all operating conditions.

On the other hand, the pressure medium supply via a non-return valve with a small passage cross-section or via both check valves connected in parallel at the same time with an enlarged passage cross-section in the pressure medium inlet connection can be performed by a in the pressure medium inlet connection in the forward direction before the check valve prevailing pressure medium (differential pressure) dependent opening a check valve or both check valves.

In this way, especially in operating conditions in which a sufficient pressure medium pressure in the pressure fluid system for quick adjustment of the camshaft adjusting device is present, for example, in high-speed operation in hot or cold condition of the engine, by simultaneously opening both check valves in parallel operation over the State of the art increased adjustment speed of the camshaft adjusting device achievable.

Furthermore, since the pressure-dependent opening and closing of the non-return valves takes place automatically, complex control means are avoided at the same time.

In this case, the first and second check valve on different opening pressures, wherein the opening pressure required to open the check valve pressure difference between the pressure medium before and behind the check valve in the pressure medium inlet connection (differential pressure) is to be understood. If the first check valve is designed with a low opening pressure and the second check valve with a higher opening pressure, the pressure medium flow is passed through the low opening pressure having a first check valve, while the higher opening pressure having second check valve remains closed at a pressure medium loading in a low pressure medium pre-operating condition. Since the first check valve opens at low differential pressure, a fast opening of the same is achieved with a low pressure medium admission pressure and a high pressure medium passage with a high adjustment speed is achieved with a small flow resistance.

Preferably, the first check valve has a small passage cross-section. In this case, the passage cross-section can be reduced for optimization so that in the operating state at low pressure medium admission pressure throttling the pressure medium supply by the first check valve impairing the adjustment is barely avoided. As a result, the blocking body of the first check valve is executable with the lowest possible passage cross-section with the lowest possible mass and lowest possible inertia, whereby particularly short reaction times of the first check valve during opening and locking of the pressure medium inlet connection can be achieved.

In this way, for example, in the hot idle phase or during warm start of the engine at a very low pressure medium level in the pressure medium system, the pressure medium supply during an adjustment over the opened first check valve with a small passage cross-section with short reaction times and optimized adjustment.

If the higher pressure medium admission pressure (differential pressure) required for opening the second check valve is reached when the pressure medium admission pressure in the pressure medium supply connection increases, the second check valve opens automatically and the pressure medium supply takes place simultaneously via both check valves connected in parallel. As a result, with an enlarged passage cross-section in the pressure medium inlet connection, the pressure medium flow rate is increased.

The opening pressure of the second check valve can be adjusted such that when the pressure medium admission pressure in the pressure medium inlet connection by opening the second check valve, a deterioration of the adjustment by a throttle effect of the first check valve is barely avoided. An optimal setting is achieved when the opening pressure of the second check valve corresponds to the pressure medium pressure (differential pressure) in the pressure medium inlet connection, in which a swinging back of the wings in the pressure chambers is reduced so far that the first check valve is permanently open. On the one hand, too early opening of the second check valve at low pressure medium admission pressure with the consequence of slower reaction times when opening and blocking the Druckmittelzulaufverbindung is prevented and on the other hand, a timely opening of the second check valve to avoid throttle effect in individual operation guaranteed. As a result, an optimized pressure medium flow in parallel operation can be achieved at high pressure medium pre-pressure for rapid adjustment. In this way, for example, in high-speed operation in hot or cold condition of the engine optimum adjustment dynamics possible.

Brief description of the drawings

Figur 1:

eine perspektivische Teilseitenansicht der Nockenwellenverstellvorrichtung,

Figur 2:

eine vereinfachte schematische Darstellung des Aufbaus des Druckmittelsystems der Nockenwellenverstellvorrichtung.

Further features of the invention will become apparent from the following description and from the drawings, in which an embodiment of the invention is shown in simplified form. Show it:

FIG. 1:

a perspective partial side view of the camshaft adjusting device,

FIG. 2:

a simplified schematic representation of the structure of the pressure fluid system of the camshaft adjuster.

Detailed description of the drawings

FIG. 1 shows a perspective view of a hydraulic camshaft adjusting device 1 without front cover from the motor side facing away from 1a. The camshaft adjusting device 1 has a driving wheel 2 mounted rotatably on a driven part 3 for this purpose. The drive wheel can be driven via an engagement point 2a, an exemplarily illustrated, non-rotatably connected to the drive wheel 2 sprocket, on whose teeth can attack a driven by a crankshaft, not shown, chain. It is also conceivable that the drive wheel 2 is driven by a belt or wheel drive. The driven part 3 is designed as an impeller and rotatably connected via a central receptacle 3a with a camshaft, not shown, for example by means of a screw or welded connection. At the output part 3, five symmetrically distributed over the circumference, extending in the radial direction wings 10 are formed. Starting from the outer circumference 3b, the driven part 3 has radial recesses forming, axially extending vane grooves 3c, in which the vanes 10 are arranged rotatably connected to the driven part 3. On the motor side facing away 1a and on the engine facing Side 1 b of the camshaft adjusting device 1 is a side cover, not shown, arranged on each of the side surfaces of the drive wheel 2 and rotatably fixed on five mounting screws 11 at this. In the drive wheel 2, five symmetrically arranged pressure chambers 4 are provided in the circumferential direction. The pressure chambers are bounded in each case at two substantially radially extending, opposite boundary walls 2b, 2c adjacent projections 2d of the drive wheel 2 in the circumferential direction. In the radial direction, the pressure chambers 4 are each bounded radially outwardly by a peripheral wall 2e of the drive wheel 2 and radially inward by the outer circumference 3b of the driven part 3. In each of the pressure chambers 4 projects one of the wings 10, wherein the wings 10 are formed such that they both abut against the peripheral wall 2e as well as on the boundary walls 2b, 2c of the projections 2d can be applied. Each of the vanes 10 divides the respective pressure chamber 4 into two counteracting pressure chambers 4a, 4b.

The drive wheel 2 is arranged rotatable in a defined angular range to the output part 3. The angular range is limited in a direction of rotation in that the wings 10 come to rest on a formed on the boundary wall 2 b of the pressure chamber 4 late stop 12. Similarly, the angle range in the other direction of rotation is limited by the fact that the wings 10 come to rest on the formed on the opposite boundary wall 2c of the pressure chamber early stop 13. FIG. 1 shows the camshaft adjuster 1 in the maximum late position at which the wings 10 are applied to the late stop 12. In order to avoid high loads when striking the wings 10 in the weakened by the axial bore 3d region of the driven part 3, the two adjacent to the axial bore 3d arranged wings 10 are released when reaching the maximum early or late position and beat on the respective boundary walls 2b , 2c not on.

By pressurizing a group of pressure chambers 4a, 4b and depressurizing the other group of pressure chambers 4a, 4b, the angular phase position of the drive wheel 2 relative to the driven part 3 in the direction of rotation of the camshaft adjusting device 1 in the direction of earlier control times (opening and closing times) of the gas exchange valves, not shown or against the direction of rotation of the camshaft adjusting device 1 are varied in the direction of later timing. By applying pressure medium to both groups of pressure chambers 4a, 4b, the phase position of drive wheel 2 and driven part 3 relative to each other can be kept constant.

For the supply of pressure medium to or pressure medium removal from the pressure chambers 4a, 4b, a pressure medium system is provided which comprises a pressure medium pump 14, a tank 15, a control valve designed as a hydraulic control device 5 and the pressure medium connections 16, 17. As hydraulic pressure medium usually the lubricating oil of the internal combustion engine is used.

About a locking unit 18 output member 3 and drive wheel 2 are mechanically coupled. The locking unit 18 has an axially displaceable in an axial bore 3d in the driven part 3 arranged locking bolt 18a, which can engage in the locked state on the driven part 3 facing the inside of the side cover, not shown in a complementarily shaped recess. In order to transfer the locking pin 18a from the locked to the unlocked state, it is provided that the recess is acted upon by pressure medium. As a result, the locking bolt 18a is pushed back against the force of the spring element into the axial bore and thus the coupling between the drive wheel 2 and the driven part 3 is canceled. The pressure medium is applied to the recess via the pressure medium connection 16 between the control valve and the pressure chambers 4a.

FIG. 2 shows in a hydraulic diagram very schematically and by way of example the structure of the pressure medium system of the camshaft adjusting device 1. There is a cross section through one of the five pressure chambers 4, each by a wing 10 in a first pressure chamber 4a and a second pressure chamber 4b are divided, indicated. The pressure medium supply and the pressure medium discharge to and from the groups of the pressure chambers 4a, 4b takes place via separate pressure medium connections 16, 17 between these and the control valve designed as a control device 5. It is provided that the control valve, the pressure medium flows to and from the first and second Pressure chambers 4a, 4b regulated. Two ports A, B connect the control valve to the pressure chambers 4a, 4b. A first working port A communicates with the pressure medium connection 16, via which the group of the first pressure chamber 4a is supplied with pressure medium. The second working port B communicates with the pressure medium connection 17, via which the group of the second pressure chambers 4b is supplied with pressure medium. Via an inlet connection P, the control valve is connected to a pressure medium supply device 7. For this purpose, a pressure medium inlet connection 6 is provided, which connects the control valve with the pressure medium supply device 7. The pressure medium supply means 7 consists of a pressure medium pump 14, which provides the camshaft adjusting device 1 permanently a pressure medium flow available, and designed as a tank 15 pressure medium reservoir. Via a discharge port T, which communicates directly with a pressure medium drain connection 19, the pressure medium can flow into the tank 15. The ports P and T may be connected to the engine oil circuit of the engine, for example, the cylinder head gallery, the oil pressure of which depends on engine speed and oil temperature. The port P then allows the supply of pressure medium in the camshaft adjusting device 1 from the oil circuit of the engine, while via the port T, the displaced in the camshaft adjusting device 1 oil can flow back into the oil circuit of the engine.

The control valve, which may be designed as a plug-in valve or as a central valve, consists of an electric actuator 5a and a hydraulic section 5b. The hydraulic section 5b has a valve housing 5c and an axially displaceable control piston 5d. Depending on the electrical energization of the electric actuating unit 5a, the control piston 5d in the valve housing 5c can be displaced axially. The spring force acting in the opposite direction of a valve spring 5e enables a return of the control piston 5d. By axial displacement of the control piston 5d, the working ports A, B can be selectively connected to the inlet port P, the drain port T or neither. In the in FIG. 2 schematically indicated control piston 5d, the internal connections of the terminals of the control valve are shown symbolically for three switching positions 5f, 5g, 5h. In order to shift the timing (opening and closing times) of the gas exchange valves, not shown in the direction of earlier timing, the first working port A is connected to the inlet port P and the second working port B to the drain port T in the advanced position 5f of the control valve. As a result, the group of the first pressure chambers 4a is acted upon by the pressure medium connection 16 with pressure medium. At the same time, pressure medium from the group of second pressure chambers 4b passes via pressure medium connection 17 to the control valve and is ejected into the tank 15 via the outlet connection T. Due to the resulting pressure difference between the two groups of pressure chambers 4a, 4b, the vanes 10 can execute oscillating movements in the pressure chambers corresponding to the alternating torques acting on the camshaft. Since there is a higher pressure medium pressure in the group of the first pressure chambers 4a than in the group of the second pressure chambers 4b, the vibration angle in the direction of late is smaller than in the direction of early. Characterized the wings 10 are moved in periodic swinging movements in the direction of the early stop 13, whereby a rotary movement of the driven part 3 is achieved relative to the drive wheel 2 in the early direction. Analogously, an adjustment in the direction of later control times in the trailing position 5h is achieved. Here, the second working port B is connected to the inlet port P and the first working port A to the drain port T. In this case, by pressurizing the group of the second pressure chambers 4b via the pressure medium connection 17 and simultaneous discharge of pressure medium from the group of the first pressure chambers 4a via the pressure medium connection 16 via the discharge port T in the tank 15 in the group of the second pressure chambers 4b a higher pressure medium pressure than generated in the group of the first pressure chambers 4a. As a result, the swing angle of the wings 10 in the direction of early is smaller than in the direction of late. In this way the wings 10 are moved in periodic oscillatory movements in the direction of the late stop 12 and achieved a rotational movement of the driven part 3 relative to the drive wheel 2 in the direction of late. The adjustment in the direction of the spring takes place counter to the forces acting on the camshaft friction moments, while assisting in an adjustment in the late direction, the friction forces acting on the camshaft support the adjustment. In order to keep the control times constant, the pressure medium supply to all pressure chambers 4a, 4b is suppressed (switching position 5g). As a result, the wings 10 are hydraulically clamped within the respective pressure chambers 4 and prevents a rotational movement of the driven part 3 relative to the drive wheel 2.

In the advanced position 5f the Druckmittezulaufverbindung 6 is via the inlet port P and the working port A of the control valve with the group of the first pressure chambers 4a in fluid communication. Analogously, in the trailing position 5h, the pressure-medium inlet connection 6 and the group of the second pressure chambers 4b are connected to one another via the inlet connection P and via the working connection B of the control valve.

In the pressure medium inlet connection 6 between the control valve and the pressure medium supply means 7, a first check valve 8 and a parallel to this second check valve 9 are arranged, via which the pressure medium inlet connection 6 in the direction of the pressure medium supply means 7 can be blocked.

Since the check valves 8, 9 in the forward direction at a Druckmittelbeaufschlagung the passage of the pressure medium only at the respective opening pressure, ie the opening respectively required differential pressure before and behind the check valve 8, 9, allow, during an adjustment both in the advanced position and in the Nacheilstellung of the control valve in the pressure medium inlet connection 6 pressure medium flow only in the direction of the group of the first pressure chambers 4a and 4b in the direction of the group of the second pressure chambers. If the respective differential pressure required for opening is not reached, the check valves 8, 9 each close automatically and lock directly in the pressure medium feed connection 6 the passage of the pressure medium in the direction of the pressure medium supply device 7. This is a reverse flow of the pressure medium from the pressure medium inlet connection 6 in the pressure medium supply means 7 reliably prevented during an adjustment.

In the forward direction, the pressure medium flow is conducted via the low opening pressure having a first check valve 8, while a higher opening pressure having second check valve 9 is closed at a pressure medium in the operating state low pressure medium pre-pressure. In this case, the first check valve 8 opens at a very small opening pressure. As a result, pressure medium can quickly be fed into the pressure chambers 4a, 4b to be filled during the adjustment process when the wings 10 oscillate in the adjustment direction with low differential pressure and low flow resistance at low reaction times. At the same time the back swing of the wings in the pressure chambers 4 against the adjustment and falls below the differential pressure required to open by quickly blocking the passage of the pressure medium in the direction of the pressure medium supply means 7 prevents a backflow of the pressure medium.

At low passage cross-section, the first check valve 8 is designed with a blocking body 8b low mass and low inertia, whereby particularly short reaction times for opening and locking the pressure medium inlet connection 6 are achieved.

In this way, at low engine speeds and high pressure medium temperatures, when the pressure medium supply pressure provided by the pressure medium supply means 7 is at a very low level, for example in the so-called hot idle phase of the engine in the engine speed range from about 600 U / min to about 900 U / min. and at a pressure medium temperature of about 140 ° C, optimizes high adjustment speeds possible.

With increasing pressure medium pre-pressure in the pressure medium inlet connection 6, the flow resistance increases in the pressure medium inlet connection on the first check valve 8 and when reaching the required to open the second check valve 9 differential pressure, this opens automatically. The pressure medium supply is then at higher pressure medium upstream pressure via both parallel check valves 8, 9 simultaneously. In parallel operation, the passage cross section in the pressure medium inlet connection 6 is increased compared to the individual operation. As a result, a larger flow of pressure medium into the pressure chambers 4a, 4b to be filled and the adjustment speed can be increased during an adjustment process at high pressure medium admission pressure via the pressure medium inlet connection 6.

The opening pressure of the second check valve 9 is set according to a pressure medium upstream pressure (differential pressure) in the pressure medium inlet connection 6, in which the first check valve 8 is permanently open when the engine speed increases. A generated by the swinging back of the wings 10 in the pressure chambers 4 overpressure in the pressure medium inlet connection 6 then no longer has an effect. In this case, the second check valve 9 opens at a prevailing in the pressure medium inlet connection 6 pressure medium upstream pressure (differential pressure), in which a Verstellgeschwindigkeit impairing throttling of the pressure medium supply through the small passage cross section at the first check valve 8 is reliably prevented. In this way, an optimally high pressure medium flow is ensured in the pressure medium inlet connection 6 with an optimal adjustment dynamics with increasing engine speed in parallel operation with both open check valves 8, 9.

When the opening pressure is optimized, the second check valve 9 opens in a warm state of the engine, for example at a pressure medium temperature of about 140 ° C at an engine speed of about 1700 U / min.

In the cold state of the engine at low pressure medium temperatures required for opening the second check valve pressure medium admission pressure (differential pressure) is achieved in the pressure medium inlet connection due to the high viscosity and density of the pressure medium even at very low engine speeds. As a result, stands during an adjustment even at low Pressure medium temperatures, at an engine cold start or a high-speed engine operation in a cold state, in parallel operation with both open check valves 8, 9 an optimized high pressure medium flow in the pressure medium inlet connection 6 available.

The first and the second check valve 8, 9 are each carried out with a by the spring force of a valve spring 8a, 9a in the reverse direction loaded locking body 8b, 9b hermetically seals the pressure medium inlet connection in the locked direction to the pressure medium supply means 7. In this case, the valve spring 8a of the first check valve 8 has a low spring force. This opens at low opening pressure. The valve spring 9a of the second check valve 9 is formed with a larger spring force, whereby a larger differential pressure for opening the same in the pressure medium inlet connection 6 is required.

LIST OF REFERENCE NUMBERS

1

Camshaft adjusting device

1a

motor side facing away

1 b

motor-facing side

2

drive wheel

2a

point of attack

2 B

boundary wall

2c

boundary wall

2d

head Start

2e

peripheral wall

3

stripping section

3a

admission

3b

outer periphery

3c

vane

3d

axial bore

4

pressure chamber

4a

first pressure chamber

4b

second pressure chamber

5

regulator

5a

actuator

5b

hydraulic section

5c

valve housing

5d

spool

5e

valve spring

5f

lead position

5g

switch position

5h

trailing position

6

Pressure inflow connection

7

Pressure fluid supply means

8th

check valve

8a

valve spring

8b

blocking body

9

check valve

9a

valve spring

9b

blocking body

10

wing

11

fixing screw

12

late stop

13

early stop

14

Hydraulic pump

15

tank

16

Pressure fluid connection

17

Pressure fluid connection

18

locking unit

18a

locking bolt

19

Pressure fluid outlet connection

A

working port

B

working port

P

inflow connection

T

drain connection

Claims (5)

1. Camshaft adjustment device (1) with a driving wheel (2) and an output part (3) arranged rotatably relative thereto, wherein the driving wheel (2) and output part (3) are operatively connected via at least one pressure space (4) which can be acted upon by pressure medium, and at least one regulating device (5) is provided for regulating the supply of pressure medium to the pressure space (4) and the removal of pressure medium from the pressure space (4), and wherein, for the supply of pressure medium, at least one pressure medium inflow connection (6) is formed between the regulating device (5) and a pressure medium supply device (7), characterized in that the passage of the pressure medium through at least two nonreturn valves (8, 9), which are connected parallel to each other, in the pressure medium inflow connection (6) can be blocked in the direction of the pressure medium supply device (7), and the first nonreturn valve (8) and second nonreturn valve (9) having different opening pressures.
2. Camshaft adjustment device (1) according to Claim 1, characterized in that the first nonreturn valve (8) is designed with a low opening pressure and the second nonreturn valve (9) is designed with a higher opening pressure.
3. Camshaft adjustment device (1) according to either of Claims 1 and 2, characterized in that the first nonreturn valve (8) has a small transmitting cross section.
4. Camshaft adjustment device (1) according to one of Claims 1 to 3, characterized in that the opening pressure of the second nonreturn valve (9) corresponds to the pressure medium pressure (differential pressure) at which the first nonreturn valve (8) is permanently open upon actuation by pressure medium.
5. Camshaft adjustment device (1) according to one of Claims 1 to 4, characterized in that, in an operating state with a high pressure medium pressure and high pressure medium temperature, the supply of pressure medium can be guided simultaneously via both nonreturn valves (8, 9).

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