EP2215331A1

EP2215331A1 - Apparatus for variably adjusting the control times of gas exchange valves in an internal combustion engine

Info

Publication number: EP2215331A1
Application number: EP08851456A
Authority: EP
Inventors: Jochen Auchter; Andreas Hempfling
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2007-11-24
Filing date: 2008-11-04
Publication date: 2010-08-11
Anticipated expiration: 2028-11-04
Also published as: CN102625874B; KR101468262B1; EP2215331B1; KR20100097117A; DE102007056683A1; US20100313834A1; CN102625874A; ATE514839T1; WO2009065728A1

Abstract

An apparatus for variably adjusting the control times of gas exchange valves in an internal combustion engine. The apparatus has a driving element, an output element, at least one pressure chamber, a pressurized medium supply device, and at least one pressure accumulator. The pressurized medium supply device allows pressurized medium to be fed to or discharged from the at least one pressure chamber. A phase angle of the output element relative to the driving element can be changed by supplying or discharging pressurized medium to or from the pressure chamber. The pressure accumulator encompasses a movable element that has a first pressure surface which partially delimits a storage space. The storage space is connected to the pressurized medium supply device. The movable element can be moved against the force of an energy store by pressurizing the storage space.

Description

Name of the invention

Device for the variable adjustment of the timing of gas exchange valves of an internal combustion engine

description

Field of the invention

The invention relates to a device for the variable adjustment of the timing of gas exchange valves of an internal combustion engine with a drive element, an output element, at least one pressure chamber, a pressure medium supply device and at least one pressure accumulator, by means of the pressure medium supply means of the at least one pressure chamber pressure medium supplied or can be removed from this, wherein a phase position of the output element relative to the drive element is variable by pressure medium supply to or pressure medium discharge from the pressure chamber, wherein the pressure accumulator has a displaceable element which is provided with a first pressure surface which partially defines a storage space, wherein the storage space is connected to the pressure medium supply device, wherein the displaceable element can be moved against the force of a force accumulator by pressurizing the storage space.

Background of the invention

In modern internal combustion engines devices for variable adjustment of the timing of gas exchange valves are used to make the phase relation between the crankshaft and camshaft in a defined Winkelbe- rich, between a maximum early and a maximum late position variable. The device usually comprises an adjusting device, which is driven by a crankshaft and transmits its torque to the camshaft. In this case, within the actuating device, a hydraulic trained raulischer actuator, which makes it possible to influence the phase angle between the crankshaft and camshaft targeted. To supply the adjusting device with pressure medium, a pressure medium supply device is provided.

Such a device is known, for example, from EP 1 025 343 B1. The device comprises two mutually rotatable rotors, wherein an outer rotor is in driving connection with the crankshaft and the inner rotor is rotatably connected to the camshaft. The device comprises a plurality of cavities, wherein each of the cavities is divided by means of a wing into two counteracting pressure chambers. By supplying pressure medium to or pressure fluid removal from the pressure chambers, the wings are moved within the pressure chambers, whereby a targeted rotation of the rotors to each other and thus the camshaft is caused to the crankshaft.

The pressure fluid inlet to, or the pressure drain from the pressure chambers is controlled by a pressure medium supply device, the pump, a pressure medium, a tank, a control valve, and a plurality of pressure medium lines comprises. In this case, a pressure medium line connects the pressure medium pump with the control valve. In each case a further pressure medium line connects one of the working ports of the control valve with the pressure chambers. The pressure medium is usually taken from the lubricant circuit of the internal combustion engine.

In order to ensure the function of the device, the pressure in the pressure medium system in each Bethebsphase the internal combustion engine must exceed a certain value. This is critical especially in the idling phases of the internal combustion engine, since the pressure medium pump is driven by the crankshaft and thus the system pressure increases with the speed of the internal combustion engine. The system pressure provided by the pressure medium pump is further dependent on the pressure medium temperature, wherein the system pressure decreases with increasing temperature. Thus, the pressure medium pump must be designed such that under the most unfavorable conditions it provides sufficient system pressure to ensure a sufficiently rapid adjustment of the phase angle of the inner rotor to the outer rotor. In order to ensure the required adjustment speed even under the most unfavorable pressure conditions, such as high pressure medium temperatures and / or low speeds, the pressure medium pump must be designed accordingly. This means that pressure medium pumps are used, which are designed for the peak requirements of the adjusting device and thus are dimensioned too large during most operating phases of the internal combustion engine. Alternatively, controllable pressure medium pump can be used, which provide demand-pressure means available. In both cases, the increased effort has a negative effect on the costs, the space requirement and the fuel consumption of the internal combustion engine.

In US 5,775,279 A discloses another such device. In this embodiment, a pressure accumulator is arranged between the pressure medium pump and the control valve, which communicates with the pressure medium supply device. This accumulator is filled in phases of high system pressure with pressure medium. If the system pressure drops, the accumulator automatically empties, whereby the Druckmittelversorgungseinhchtung additional pressure medium is provided. Thus, the phase adjustment of the device is supported.

A disadvantage of this embodiment is the fact that the pressure accumulator is emptied even if the system pressure is not due to an adjustment process, but due to other external circumstances, for example by a decrease in the speed drops. Thus, for a subsequent Phasenverstellvorgang lower pressure support and a lower pressure medium volume from the pressure accumulator available. A further disadvantage is that the maximum pressure with which the pressure accumulator can support the pressure medium supply device corresponds to the pressure which prevailed directly before the phase adjustment process in the pressure medium supply device. Is at high temperatures and low speeds of the engine control an adjustment to the Directed device, the pressure support of the pressure accumulator falls lower because the system pressure with which the pressure accumulator was filled, was low. This can result in that the adjustment process can not be carried out, or the adjustment speed is significantly reduced. Thus, an interpretation of the pressure medium pump on the peak load with the resulting disadvantages is also required in this case.

Object of the invention

The invention has for its object to provide a device for variable adjustment of the timing of gas exchange valves of an internal combustion engine, with a functionally reliable adjustment of the timing should be ensured at high adjustment speeds in each phase of operation of the internal combustion engine. It should also be possible to dispense with an oversizing of the pressure medium pump (design for the expected peak loads) as well as the use of variable pressure medium pumps.

The object is achieved in that the displaceable element has at least a second pressure surface, which limits a control chamber partially, which can be displaced by pressurizing the control chamber, the movable element against the force of the energy storage and wherein within the pressure accumulator, a pressure medium flow from the storage room in the control room is prevented.

It can be provided that the reservoir and the control chamber do not communicate with each other within the pressure accumulator.

The displaceable element can for example be designed as a pressure piston, which can be displaced within a pressure vessel against the force of an energy accumulator designed as a spring element. Alternatively, other forms of energy storage can be used, for example, reversibly deformable body, for example made of elastomers, or gas-filled bubbles. Due to the design of the accumulator with a verlagerba ren element, which partially isolated spaces within the pressure accumulator, these two spaces can be controlled separately, ie filled and / or emptied, be. Apart from leakage there is no connection between the rooms. For example, different pressure sources for filling the storage space and the control room can be used.

Alternatively, a pressure medium connection between the reservoir and the control chamber can be provided within the pressure accumulator. Pressure medium which is supplied to the control room, can get over this pressure medium connection in the storage room. However, it should be noted that a reverse flow of pressure medium, is prevented by the storage space in the control room. This can be realized for example via a pressure medium channel in the pressure piston or the housing of the pressure accumulator, in which a check valve is arranged. In this case, the filling of the storage space and the control room can be done solely by the filling of the control room. If the accumulator is emptied, the control room is switched to tank. The storage room empties into the pressure medium supply device, the control chamber depressurized into the tank. A transfer of pressure medium from the reservoir into the control chamber is prevented by the check valve.

If it is provided that a pressurization of the reservoir displaces the displaceable element in the same direction as a pressurizing of the control chamber, the control chamber can support the filling of the reservoir space. For this purpose, the control chamber is also filled with pressure medium during the filling process of the storage space. As a result, a force acts on both pressure surfaces of the pressure piston, whereby a higher force is stored in the energy store (the spring element is compressed more strongly). Receives the filled pressure accumulator from the engine control command to support the Phasenverstellvorgang, so the control room can be emptied independently of the storage room. That is, while the storage space is emptied into the pressure medium supply device, and thus supports the Phasenverstellvorgang, the control room vented against atmospheric pressure in a tank. By suitable design, the venting of the control chamber can be done faster than the emptying of the reservoir into the pressure medium supply device. Thus, the entire force that was stored in the energy storage acts on the first pressure surface on the pantry. As a result, the pressure at the beginning of the assist process can be reduced by up to a factor of

A rise, depending on the load at that time on the

Energy storage acts. Here A ₁ corresponds to the surface area of the first pressure surface and A ₂ corresponds to the surface area of the second pressure surface. Is used as

Force memory, for example, a spring element used, so the pressure increases

A + A at the beginning of the support process by the full factor - 'on,

A as long as the spring has not yet reached its maximum compressed state.

The invention is based on the fact that in a device for variably setting the timing of gas exchange valves of an internal combustion engine with a drive element, an output element, at least one pressure chamber, a pressure medium supply device and at least one pressure accumulator, wherein by means of

Pressure medium supply means of the at least one pressure chamber can be supplied with pressure medium or removed therefrom, wherein a phase position of the output element relative to the drive element is variable by pressure medium supply to or pressure medium discharge from the pressure chamber, a displaceable element of the pressure accumulator at least two independently formed and pressurizable spaces in Displacement direction of the element limited. In this case, at least one of the spaces (storage space) is connected to the pressure medium supply device and can be emptied into the pressure medium supply device during a Phasenverstellvorgangs. Furthermore, at least one additional space (control space) is also pressurized during the filling process of the storage space. beats and emptied faster than this during the emptying process of the storage room. This can be done, for example, against atmospheric pressure, in a tank. Thus, the control chamber supports the filling process in such a way that the displaceable element is deflected more strongly than would be the case without the center of pressure of the control chamber.

By increasing the pressure provided by the pressure accumulator, the pressure accumulator can intercept peak consumption, so that the pressure medium pump can be designed for normal operation of the internal combustion engine. There are no oversized or regulated pressure medium pumps needed to ensure a reliable and fast adjustment of the phase position. In addition, the adjustment speed of the adjusting device is increased. Alternatively, the adjusting device can be dimensioned smaller at the same adjustment speed. What can reduce the mass, the moment of inertia and the costs.

In a further development of the invention it can be provided that the control chamber can be selectively connected to a pressure source or a tank during operation of the internal combustion engine. The pressure source can be, for example, the pressure medium supply device or its pressure medium pump or a separate source, for example the pressure source of a servo consumer (eg the power steering). In the second case, the pressure accumulator can be completely filled even in operating phases with low system pressure. The selective connection to a pressure source or the tank is established via control means, for example a 3/2-way valve in the form of a switching valve (for example a seat valve) or a proportional valve (for example a slide valve). Alternatively, two control means come into consideration, one of the control means the connection pressure source -> control room and the other control means the connection control room -> tank locks or releases. The control means may be, for example, electromagnetically actuated hydraulic valves, such as directional control valves (for example switching or proportional valves), pilot operated check valves or the like. These control means receive from an engine control unit of Internal combustion engine control signals according to which the accumulator is filled or emptied. Thus, a variety of support strategies can be realized.

Also conceivable is the use of hydraulically operated control means. It can be provided that the hydraulic actuating device of the control means communicates with the pressure medium supply device. Thus, when the pressure in the pressure medium supply device drops, the control means will automatically be switched below a defined value. This reduces the regulatory burden considerably.

In a concretization of the invention it is provided that the control room, without detour via a consumer, can be emptied into a tank. In this case, the control chamber is preferably emptied against atmospheric pressure, usually via a proportional or switching valve.

In one embodiment of the invention, control means are provided, wherein the control chamber can be selectively connected by means of the control means with a tank or the pressure source. The control means may be formed, for example, as a directional control valve.

In an alternative development of the invention, it is provided that control means are provided which lock in a first state a pressure medium flow from the reservoir to the pressure medium supply device and allow a pressure medium flow to the reservoir and the control chamber and in a further state, the pressure medium flow of the Allow storage space to the pressure medium supply device and connect between the control room and a tank, without detour via a consumer produce. It can be provided that the storage space and the control chamber are connected via a check valve, wherein the connection between the control means and the spaces is arranged and wherein the check valve blocks a pressure medium flow from the storage space to the control room. Thus, it is prevented that the storage space communicates with the pressure medium supply device in operating phases of the internal combustion engine, in which no phase adjustment takes place, but the system pressure nevertheless drops. Thus, the pressure medium volume and the pressure in the reservoir are kept at a high level.

In this case, a supply line may be provided, which connects the pressure medium supply device to the storage space and be provided a control line which connects the control chamber with a pressure source. Furthermore, the control means may be formed as a single-way valve, each having a connection for the supply line, the control line, the control room, the storage room and the tank. As a result, the number of components and the control effort during operation of the internal combustion engine is reduced. Alternatively, the control means may comprise at least a first directional valve, which is arranged in the control line. Furthermore, it can be provided that the control means further comprise a second directional control valve, which is arranged in the supply line. In this case, the directional control valves can be designed, for example, as switching or proportional valves. Alternatively, the control means may further comprise a pilot operated check valve disposed in the supply line.

Advantageously, in the device according to the invention between the control chamber and the pressure source, a check valve may be provided, which blocks a pressure medium flow from the control chamber in the direction of the pressure source. Thus, the pressure medium volume located in the control chamber is trapped until it is connected to a tank. As a result, the displaceable element is held in the deflected position, even if the system pressure drops and thus prevents unwanted emptying of the storage space.

In one embodiment of the invention can be provided that between the reservoir and the pressure medium supply device, a check valve is provided, which blocks a pressure medium flow from the pressure medium supply device in the direction of the storage space. This prevents that pressure peaks that are generated in the actuator are transmitted to the pressure accumulator. Thus, the pressure fluid flowing back out of the pressure chamber of the actuating device during a pressure peak is supported on the non-return valve, thereby increasing the hydraulic rigidity of the device and thus increasing the adjustment speed and improving torque transmission from the crankshaft to the camshaft.

The pressure support of the pressure accumulator can thus be activated by simply switching one or more control means. In this case, the pressure medium volume is provided which is collected in the operating phase of the internal combustion engine in which the phase position is kept constant in the storage space. Depending on the embodiment, the pressure provided by the pressure accumulator corresponds either to the current system pressure multiplied by a factor which can amount to 1 + A ₂ / Ai or to a maximum system pressure which exists during the filling phase multiplied by the same factor. The full factor 1 + A ₂ / Ai is always present when the full storage capacity of the energy storage has not been exhausted, the spring element is not yet compressed to block or the pressure piston is still applied to the attacks. In one embodiment of the invention, it is provided that the displaceable element has a third pressure surface, which at least partially limits a counter-pressure space, wherein a pressure medium loading of the counter-pressure chamber displaces the displaceable element in the opposite direction, such as a pressurizing of the control chamber or the storage space. Thus, the pressure available from the pressure accumulator pressure is increased again, since now the force exerted by the energy storage on the displaceable element force is increased by the pressure acting on the third pressure surface, caused force.

The pressure support of the pressure accumulator can be used with every phase adjustment process. For this purpose, always the control means (Directional valves and / or unlockable check valves) in the position in which the reservoir is emptied when a phase adjustment is requested. In the operating phases between the phase adjustment requirements, the pressure accumulator can fill up. Another possibility is to switch on the pressure support of the pressure accumulator as needed. If the engine control detects that the pressure or volume flow delivered by the pressure medium pump is insufficient for phase adjustment, it releases the pressure support through the pressure accumulator. This procedure extends the times in which the accumulator can be filled and thus the performance of the pressure accumulator during pressure support.

Alternatively it can be provided to use the pressure support of the pressure accumulator only as a "boosf function for critical adjustment processes that require, for example, a high volume flow or a high adjustment speed. If the engine control system detects that such a critical adjustment procedure is to be initiated, it will release the pressure support by suitably setting the control means.

It is also conceivable to form the control means in one piece with a control valve which controls the pressure medium flow to and from the pressure chambers of the adjusting device.

In a concretization of the invention, it is proposed that the ratio between the minimum flow cross-section between the control chamber and the tank and the minimum flow cross-section between the reservoir and the actuator is greater than the ratio between the surface area of the second pressure surface and the surface area of the first pressure surface.

Advantageously, the maximum volume of the storage space corresponds to at least twice the volume required for a phase adjustment from a maximum late position to a maximum advance position. The pressure accumulator can open, for example, in the pressure medium line between the pressure medium pump and the control valve.

Alternatively it can be provided that the pressure accumulator opens into one of the pressure medium lines, which connects one of the working ports of the control valve with a group of pressure chambers. In addition, in this embodiment, a second pressure accumulator may be provided, which opens into the pressure medium line, which connects the other working port of the control valve with the other group of pressure chambers.

Brief description of the drawings

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

FIG. 1 shows very schematically an internal combustion engine,

Figure 2a shows a longitudinal section through the adjusting device

FIG. 2b shows a cross section through an adjusting device,

FIG. 3 shows a first embodiment of a device according to the invention,

Figure 4 - 12 further embodiments of a device according to the invention.

Detailed description of the drawings

1 shows an internal combustion engine 1 is sketched, wherein a seated on a crankshaft 2 piston 3 is indicated in a cylinder 4. The crankshaft 2 is in the illustrated embodiment via a respective traction drive 5 with an intake camshaft 6 and exhaust camshaft 7 in combination, with a first and a second device 10 for a relative rotation between the crankshaft 2 and the camshafts 6, 7 can provide. The devices 10 each comprise a hydraulic actuating device 10a, b, c and a pressure medium supply device 37. Cams 8 of the camshafts 6, 7 actuate one or more inlet gas exchange valves 9a or one or more exhaust gas exchange valves 9b. Likewise, it may be provided to equip only one of the camshafts 6, 7 with a device 10, or to provide only one camshaft 6, 7, which is provided with a device 10.

FIG. 3 shows a first embodiment of a device 10 according to the invention, with adjusting devices 10a, b, c of a pressure medium supply device 37 and a pressure accumulator 43. FIGS. 2a and 2b show an adjusting device 10a, b, c in longitudinal section or in cross section.

The adjusting device 10a, b, c has a drive element designed as an outer rotor 22 and an output element designed as an inner rotor 23. The outer rotor 22 has a housing 22a and two side covers 24, 25 disposed on the axial side surfaces of the housing 22a. The inner rotor 23 is designed in the form of an impeller and has a substantially cylindrically designed hub member 26, extend from the outer cylindrical surface in the illustrated embodiment, five wings 27 in the radial direction outwards. The vanes 27 are formed separately from the inner rotor 23 and arranged in vane grooves 28 formed on the hub member 26. The vanes 27 are acted upon radially outwardly by means of winged springs 27a, which are arranged between the groove bottoms of the vane grooves 28 and the vanes 27.

Starting from an outer peripheral wall 29 of the housing 22a, a plurality of projections 30 extend radially inwardly. In the illustrated embodiment, the projections 30 are formed integrally with the peripheral wall 29. The outer rotor 22 is mounted by means of radially inner circumferential walls of the projections 30 relative to the inner rotor 23 rotatably mounted on this.

On an outer circumferential surface of the peripheral wall 29, a sprocket 21 is arranged, by means of which, via a chain drive, not shown, torque can be transmitted from the crankshaft 2 to the outer rotor 22. Depending on one of the side covers 24, 25 is arranged on one of the axial side surfaces of the housing 22a and rotatably fixed thereto. For this purpose, an axial opening is provided in each projection 30, which is penetrated by a fastening element 32, for example a screw, which serves for the rotationally fixed fixing of the side covers 24, 25 on the housing 22a.

Within the adjusting device 10a, b, c, a cavity 33 is formed between two respective projections 30 adjacent in the circumferential direction. Each of the cavities 33 is bounded circumferentially by opposing substantially radially extending boundary walls 34 of adjacent protrusions 30, axially from the side covers 24, 25, radially inwardly of the hub member 26 and radially outward of the peripheral wall 29. In each of the cavities 33 projects a wing 27, wherein the wings 27 are formed such that they rest against both the side covers 24, 25, and on the peripheral wall 29. Each wing 27 thus divides the respective cavity 33 into two counteracting pressure chambers 35, 36th

The inner rotor 23 is rotatable in a defined Winkeibreich to the outer rotor 22. The angular range is limited in one direction of rotation of the inner rotor 23 in that the wings 27 come to rest on a respective boundary wall 34 (early stop 34a) of the cavities 33. Similarly, the angular range in the other direction of rotation is limited by the fact that the wings 27 come to rest on the other boundary walls 34 of the cavities 33, which serve as a late stop 34b.

By pressurizing a group of pressure chambers 35, 36 and pressure relief of the other group, the phase angle of the outer rotor 22 to the inner rotor 23 can be varied. By pressurizing both groups of pressure chambers 35, 36, the phase position of the two rotors 22, 23 are kept constant to each other. Alternatively it can be provided, none of the pressure chambers 35, 36 during phases of constant phase position with Apply pressure medium. As hydraulic pressure medium usually the lubricating oil of the internal combustion engine 1 is used.

For supplying pressure medium to or removing pressure medium from the pressure chambers 35, 36, a pressure medium supply device 37 is provided, which is shown in FIG. The pressure medium supply device 37 comprises a pressure source, which is designed as a pressure medium pump 38, a tank 39, a control valve 40 and a plurality of pressure medium lines 41. The control valve 40 has an inlet port P, a tank port T and two working ports A, B on. In each case one of the pressure medium line 41 connects the pressure medium pump 38 with the Zuiaufanschluss P, the first working port A with the first pressure chamber 35, the second working port B with the second pressure chamber 36 and the tank port T to the tank 39. Thus, pressure medium from the pressure medium pump 38 via the pressure medium line 41 to the inlet port P of the control valve 40 pass.

In a first position of the control valve 40, the inlet port P is connected to the first pressure chambers 35, while the second pressure chambers 36 are connected to the tank 39. In a second position of the control valve 40 is provided that none of the pressure chambers 35, 36 communicates with the tank 39 and the inlet port P.

In a third position of the control valve 40, the inlet port P is connected to the second pressure chambers 36, while the first pressure chambers 35 are connected to the tank 39.

During operation of the internal combustion engine 1 acts on the camshaft 6, 7 a change moment, which is caused by the rolling of the cam 8 on Nockenfolgem. The force of valve springs until the complete opening of the gas exchange valve braking effect on the camshaft 6, 7 a. Subsequently, the camshaft 6, 7 is accelerated by the force of the valve springs. As a consequence, within the control device 10a, b, c, pressure peaks are generated, which lead to the pressure chambers 35, 36 connected to the inlet port P being in opposition to the pressure ports Pressure medium pump 38 are emptied, resulting in a significant reduction in the adjustment speed. To prevent this, a check valve 42 a is provided in the pressure medium line 41 which connects the pressure medium pump 38 to the control valve 40. The check valve 42a prevents backflow of the pressure medium from the pressure chambers 35, 36 via the control valve 40 to the pressure medium pump 38. The pressure peaks are based on the check valve 42a, whereby an unwanted emptying of the pressure chambers 35, 36 is effectively prevented and thus the stiffness of the torque transmission and the adjustment speed is increased.

The adjustment speed of the actuating devices 10a, b, c is dependent on the pressure provided or the pressure medium volume flow of the pressure medium pump 38 provided. The pressure provided or the pressure medium volume flow provided are in turn dependent on a multiplicity of factors, for example on the rotational speed of the internal combustion engine 1 and the pressure medium temperature. In order to ensure the required adjustment speed even in the most unfavorable conditions, such as high pressure medium temperatures and or low speeds, the pressure medium pump 38 must be designed accordingly. As a result, pressure medium pumps 38 are used, which are designed for the peak requirements of the actuating device 10a, b, c and are thus dimensioned too large during most operating phases of the internal combustion engine 1. Alternatively, controllable pressure medium pumps 38 can be used which provide pressure medium as needed. In both cases, the increased expense has a negative effect on the cost and fuel consumption of the internal combustion engine 1.

In order to avoid these disadvantages, a pressure accumulator 43 is provided in the device 10 according to the invention. The pressure accumulator 43 comprises a displaceable element designed as a pressure piston 45, which can be displaced within a pressure vessel 44 against the force of an energy accumulator. In the illustrated embodiment, the energy accumulator is designed as a spring element 46. However, other types of force gearing are also conceivable. such as suitably shaped elastomeric bodies or gas filled bladders.

The pressure piston 45 has two pressure surfaces 47, 48. Together with the pressure vessel 44 limits the first pressure surface 47 a reservoir 49 and the second pressure surface 48 a control chamber 50. In this case, the pressure piston 45 and the pressure vessel 44 are formed such that within the pressure accumulator 43 is no connection between the two spaces 49 and 50. In the illustrated embodiment, the displacement path of the pressure piston 45 is limited by stops 54 for this purpose

The storage space 49 is connected by means of a supply line 51 to the pressure medium supply device 37, wherein the supply line 51 downstream of the check valve 42a opens into this. The control chamber 50 can optionally be connected to a tank 39 or by means of a control line 52 to a pressure source or. In the illustrated embodiment serves as a pressure source, the pressure medium supply means 37. Also conceivable, however, that another pressure source, such as the pressure medium pump 38 of a servo load, eg. The power steering, is used. In this case, the pressure fluid flowing out from the control chamber 50 is not directed into the tank 39 of the lubricating oil circuit of the internal combustion engine 1, but to the corresponding tank 39 of the servo consumer.

In order to control the pressure medium flow to and from the control chamber 50, a control means 60 in the form of a first directional valve 53 is provided. The first directional control valve 53 has a pressure port Pi, a control chamber port Ai and a discharge port Ti. The pressure port P ₁ is connected to the pressure source, in the illustrated embodiment via the control line 52 to the pressure medium supply means 37. The control chamber connection A ₁ is connected to the control chamber 50 and the drain port T ₁ to the tank 39. In a first control position of the first directional control valve 53, the control chamber connection A _{1 is} connected to the pressure connection P ₁ , while the outflow connection T _{1 is} connected to none of the other Ports P ₁ , Ai communicates.

In a second control position of the first directional control valve 53 of the control chamber terminal Ai is connected to the drain terminal Ti, while the pressure port P ₁ with any of the other terminals T _1, A ₁ communicates.

In addition, a further check valve 42b may be provided, which is arranged in the control line 52 and prevents backflow of pressure medium from the control chamber 50 to the pressure medium supply device 37. If no adjustment request is directed to the device 10 during operation of the internal combustion engine 1 by the engine control, then the control valve 40 is in the second (middle) position and the first directional control valve 53 is in the first position. Consequently, no pressure fluid flows to or from the actuator 10a. At the same time pressure medium passes both via the supply line 51 into the reservoir 49 and via the control line 52 into the control chamber 50. The introduced into the reservoir 49 and the control chamber 50 pressure acting on the pressure surface 47 and the pressure surface 48 whereby the pressure piston 45 in Direction of the stops 54 is displaced against the force of the spring element 46, so that the volume of both the control chamber 50 and the storage space 49 increases. Due to the pressure gradient between the control chamber 50 and the pressure medium supply device 37 closes the check valve 42b in the control line 52, whereby a pressure drop in the control chamber 50 and a pressure medium flow is avoided from this. This has the consequence that the volume of the control chamber 50 and the storage space 49 remains constant despite the pressure drop in the pressure medium supply device 37. In this case, for the way x, the pressure piston 45 has been deflected from its rest position:

D where A ₁ corresponds to the surface area of the first pressure surface 47, A ₂ corresponds to the surface area of the second pressure surface 48, p _ma χ the maximum system pressure occurring during the filling phase, and D is the spring constant of the spring element 46. speaks. The maximum displacement is limited by the stops 54. Under the rest position is the state of the pressure piston 45 to understand, in which the spring element 46 is maximally relaxed. If a phase angle adjustment is requested by the engine control unit, the control valve 40 is transferred into its first or third position. Thus, pressure medium from the pressure medium pump 38 passes to the first and second pressure chambers 35, 36, whereby a phase adjustment by the actuator 10a, b, c is caused. If the volume flow delivered by the pressure medium pump 38 is too low to ensure the adjustment or if a higher adjustment speed is to be achieved, the first directional control valve 53 is transferred into its second control position. In this control position, the control chamber 50 is connected to a tank 39. The under pressure in the control chamber 50 pressure medium is thus connected to atmospheric pressure, whereby a rapid draining of the control chamber 50 takes place. At the same time, the storage space 49 is emptied into the pressure medium supply device 37. Is this done?

Relieving pressure medium of the control chamber 50 so fast that the pressure piston 45 is supported exclusively on the first pressure surface 47 relative to the reservoir 49, the entire force of the spring element 46 acts only on the reservoir 49. Thus applies to the pressure p in the reservoir 49 at the beginning the emptying process:

P =

A

As long as the pressure piston 45 has not been fully deflected, so it does not abut the stops 54. Since the check valve 42a is arranged in the pressure medium line 41 upstream of the supply line 51, it is ensured that the total pressure p and the entire volume of the reservoir 49 of the actuator 10a is available and not drained into the oil gallery of the internal combustion engine 1. Thus, not only is the current system pressure or the maximum filling pressure available, as in applications with conventional pressure accumulators, but a pressure increased by the factor 1 + A ₂ / Ai. The pressure medium supply device 37 can thus by adjusting the second control position on the first Directional valve 53 undergo pressure support. Thus, the adjustment speed of the adjusting device 10a can be increased significantly with the same dimensioning or the adjusting device 10a can be made smaller at the same adjustment speed without having to accept the disadvantages of an oversized or regulated pressure medium pump 38.

Likewise conceivable are embodiments in which the arrangement of a check valve 42b in the control line 52 is dispensed with. In operating phases of the internal combustion engine 1, in which the phase position is kept constant, the pressure accumulator 43 fills in analogy to the embodiment described above. If the system pressure drops, then pressure medium flows both from the reservoir 49 and from the control chamber 50. This leads to a pressure drop in both chambers 49, 50, which leads to a displacement of the pressure piston 45 in the direction of its rest position. Thus, in this embodiment, both the pressure medium volume that can be provided for the phase adjustment and the pressure that can be provided in the storage space 49 are lowered. Nevertheless, the pressure increase in the reservoir 49 takes place when the first directional control valve 53 is transferred to the second switching position. In this case, for the pressure p provided with the pressure piston 45 not yet fully deflected, the following applies:

P = - 4 where p _sys corresponds to the system pressure prevailing at the beginning of the pressure support. Conceivable is the use of this embodiment in internal combustion engines 1 in which the required peak system pressure is only slightly above the capacity of the pressure medium pump 38. In this case, the check valve 42b in the control line 52 can be dispensed with, whereby the costs are reduced.

In order to realize the pressure increase must for the ratio of the pressure medium flow from the control chamber 50 to the pressure medium flow from the reservoir 49 Q _D / Qv Qv A 'apply. To achieve this, it is provided that for the minimum flow cross section between the control chamber 50 and the tank 39 A _D

A _D > ^ A _V

applies, wherein A _v corresponds to the minimum flow area between the reservoir 49 and the actuator 10a and the actuator 10a and the tank 39.

It is also conceivable that, in addition to the first control device 10a, one or more further control devices 10b, 10c can also be controlled by the pressure medium supply device 37 via further pressure medium lines 41 and further control valves 40. In this case, the further adjusting device 10 b can also benefit from the pressure accumulator 43. For this purpose, the branch leading to this adjusting device 10b lies downstream of the check valve 42a.

If the accumulator 43 only supported the first actuator 10a, the branch to the further actuator 10c in the flow direction in front of the check valve 42a is to be arranged.

In order to ensure the functionality of the pressure accumulator 43, a vent 46a of the spring chamber to the tank 39 is provided.

It is also conceivable to arrange the check valve 42a downstream of the branch to the supply line 51 (FIG. 4). In this case, the support of the pressure peaks between the adjusting device 10a, b and the branch to the supply line 51 takes place. The pressure peaks can thus not reach the pressure accumulator 43, as a result of which a stiffer torque transmission is achieved by the adjusting device 10a, b. Also conceivable is the use of a check valve 42a in the pressure medium line 41 upstream and downstream of the branch to the supply line 51 (FIG. 5). This is both a stiff torque transfer achieved by the actuator 10a, b and prevents the pressure, or the pressure center volume of the reservoir 49 flows into the oil gallery of the internal combustion engine 1.

Another embodiment of the device 10 according to the invention is shown in FIG. In contrast to the embodiment illustrated in FIG. 3, in this embodiment an additional check valve 42 c is arranged in the supply line 51. This check valve 42c prevents a flow of pressure medium from the pressure medium supply device 37 to the reservoir 49, which generated in the actuators 10a, b, c pressure peaks can not penetrate to the reservoir 49 of the accumulator 43, but supported on the check valve 42c. Thus, the hydraulic rigidity of the device 10 is increased analogous to the embodiment of Figure 5. In order to fill the storage space 49 of the pressure accumulator 43, a connecting line 55 is provided, which opens on the one hand between the pressure medium supply means 37 and the first directional control valve 53 in the control line 52 and on the other hand between the check valve 42c and the storage space 49 in the supply line 51. In this case, an additional check valve 42d may be arranged in the connection line 55, which prevents pressure medium from the storage space 49 between the pressure medium pump 38 and the check valve 42a from flowing into the pressure medium supply device 37. In a slight modification of the embodiment, the check valve 42b and / or the entire pressure medium line 41, in which the check valve 42a is arranged, between the orifice points of the pressure accumulator 43 could be omitted.

FIGS. 7 to 11 show further embodiments of a device 10 according to the invention. In these embodiments, control means 60 are provided both in the control line 52 and in the supply line 51, which can block the flow of pressure medium at least in one direction. In the embodiment shown in Figure 7, a single control valve in the form of a directional control valve 56 is provided. The directional control valve 56 has a pressure connection P ₁ , a control chamber connection A ₁ , a supply connection V ₁ , a reservoir connection B ₁ and a discharge connection T ₁ . The pressure connection P ₁ and the supply connection V ₁ are connected to the pressure source, in the illustrated embodiment via the control line 52 or the supply line 51 to the pressure medium supply device 37. The control chamber connection A ₁ is connected to the control chamber 50, the reservoir connection B ₁ to the reservoir 49 and the drain port T ₁ to the tank 39.

Furthermore, a connecting line 55 is provided, which opens on the one hand between the directional control valve 56 and the control chamber 50 in the control line 52 and on the other hand between the directional control valve 56 and the reservoir 49 in the supply line 51. In the connecting line 55, a check valve 42 d is arranged, which prevents a pressure medium flow from the supply line 51 to the control line 52.

In a first control position of the directional control valve 56, only the control chamber connection A _{1 is} connected to the pressure connection P ₁ , while all other connections B ₁ , T ₁ , V _{1 are} closed. In a second control position of the directional control valve 56, the supply connection V ₁ communicates with the reservoir connection B ₁ and the control chamber connection A ₁ with the tank connection T ₁ , while the pressure connection P ₁ communicates with none of the other connections A ₁ , B ₁ , T ₁ , V ₁ , communicated.

If no adjustment request is directed to the device 10 during operation of the internal combustion engine 1 by the engine control, then the directional control valve 56 is in the first control division. In this state, pressure medium from the pressure medium supply device 37 via the control line 52 and the directional control valve 56 can get into the control chamber 50. At the same time, the storage space 49 is also filled via the connecting line 55. In this state, the pressure accumulator 43 behaves similar to the pressure accumulator 43 shown in Figure 3. The pressure piston 45 is displaced against the force of the spring element 46 and the spaces 49, 50 with pressure medium filled. However, the pressure in the control chamber 50 also decreases. The reservoir 49, however, maintains the high pressure state since it is insulated on the one hand by the directional control valve 56 and on the other hand by the check valve 42d with respect to the pressure medium supply device 37. Thus, the pressure accumulator 43 maintains its filled state.

If the directional control valve 56 is transferred to the second control state, then the control chamber 50 is emptied into the tank 39 on the one hand and the reservoir 49 into the pressure medium supply device 37 on the other hand. This process is analogous to the first embodiment (FIG. 3).

FIG. 8 shows a further embodiment according to the invention, which differs from the previous embodiment only in the arrangement of the check valve 42a. In this case, the check valve 42a is arranged analogously to the embodiment from FIG. Also conceivable is an embodiment analogous to FIG. 5 with two non-return valves 42a, one upstream and downstream of the supply line 51, respectively.

FIGS. 9 to 11 show further devices 10 according to the invention which essentially resemble those of FIGS. 7 and 8. In contrast to these, the devices 10 shown in FIGS. 9 to 11 are provided with two control means 60 instead of a single control means 60 (in the illustrated embodiment with a single way valve 56). In this case, the first control means 60 controls the communication between the pressure medium supply means 37 and the storage space 49, while the second control means 60 controls the communication between the pressure medium supply means 37, the control chamber 50 and the tank 39.

In the embodiment shown in Figure 9, the first control means 60 is designed as a pilot-operated check valve 42e, which allows a pressure medium flow from the pressure medium supply means 37 to the reservoir 49 in a first control position, but an opposite pressure medium flow in derogation. In the second control position, the pressure medium flows are permitted in both directions.

The second control means 60 in this case is the first directional control valve 53 shown in the first embodiment.

In contrast to the embodiment according to FIG. 9, FIG. 10 shows an embodiment in which the pilot-operated check valve 42e is replaced by a second directional valve 57, in the specific embodiment a 2/2-way valve. In a first control position, the second directional control valve 57 does not allow any pressure medium flow between the pressure medium supply device 37 and the reservoir 49. In a second control position, the pressure medium can flow in both directions.

In contrast to the embodiment according to FIG. 10, FIG. 11 shows an embodiment in which the first directional control valve 53 has been modified such that in the first control position only one pressure medium valve is permitted by the pressure medium supply device 37 in the direction of the control chamber 50, whereas an opposite pressure medium flow is prevented in the first directional control valve 53.

FIG. 12 shows a further aspect of the invention, which will be explained with reference to the embodiment shown in FIG. It is expressly pointed out that this aspect can be used in all previous embodiments. The device 10 differs from the device 10 shown in Figure 6 in that the connecting line 55 between the first directional control valve 53 and the control chamber 50 opens into the control line 52 and that no vent 46a of the spring chamber is provided. The spring chamber is rather equipped as a back pressure chamber 58, which can be filled with pressure medium. The first directional valve 53 is provided in this embodiment with an additional back pressure port G, which communicates with the back pressure chamber 58. In a first control position of the first directional valve 53 is the Control chamber port A ₁ connected to the pressure port P ₁ , while the back pressure port G communicates with the drain port T ₁ . In a second control position of the first directional control valve 53, the control chamber connection A _{1 is} connected to the outlet connection T ₁ , while the pressure connection P ₁ communicates with the counterpressure connection G.

If the first directional control valve 53 is in the first control position, there are no changes compared to the embodiment from FIG. In the second control position, however, additional pressure medium is conducted into the counterpressure space 58. This acts on a third pressure surface 59 of the pressure piston 45 with a force acting in the same direction as the spring element 46. As a result, the pressure in the reservoir 49 is additionally increased.

In all the illustrated embodiments, the pressure accumulator 43 opens with the pressure medium line 41, which connects the pressure medium pump 38 with the control valve or valves 40. Likewise conceivable are embodiments in which the pressure accumulator 43 opens into the pressure medium lines 41, which connects the control valve or valves 40 to the actuating devices 10a, b.

In addition to the use of the pressure accumulator 43 in applications for the variable adjustment of the timing of an internal combustion engine 1, the pressure accumulator 43 can also be used in other vehicle applications, for example in switchable cam followers or in applications in automated transmissions.

reference numeral

1 internal combustion engine

2 crankshaft

3 pistons

4 cylinders

5 traction drive

6 intake camshaft

7 exhaust camshaft

8 cams

9a inlet gas exchange valve

9b outlet gas exchange valve

10 device

10a first adjusting device

10b, c further adjusting device

21 sprocket

22 outer rotor

22a housing

23 inner rotor

24 side covers

25 side lids

26 hub element

27 wings

27a wing feathers

28 wing grooves

29 peripheral wall

30 advantage

32 fastener

33 cavity

34 boundary wall

34a early attack

34b Late stop 35 first pressure chamber

36 second pressure chamber

37 pressure medium supply device

38 pressure medium pump

39 tank

40 control valve

41 pressure medium line

42a check valve

42b check valve

42c check valve

42d check valve

42e unlockable check valve

43 accumulator

44 pressure vessels

45 pressure piston

46 spring element

46a venting

47 first printing surface

48 second printing area

49 storage room

50 control room

51 supply line

52 control line

53 first directional control valve

54 stop

55 connection line

56 way valve

57 second directional valve

58 back pressure chamber

59 third printing area

60 control means

A first work connection

B second work connection P inlet connection

T drain connection

P ₁ pressure connection

T ₁ drain connection A ₁ control room connection

B-i pantry connection

V ₁ supply connection

G back pressure connection

Claims

claims

1. Device (10) for variably setting the control times of gas exchange valves (9a, b) of an internal combustion engine (1) with a drive element (22), an output element (23), at least one pressure chamber (35, 36), a pressure medium supply device (37 ) and at least one pressure accumulator (43),

Wherein by means of the pressure medium supply device (37) the at least one pressure chamber (35, 36) can be supplied with pressure medium or removed therefrom, β wherein a phase position of the output element (23) is provided by pressure medium supply to or pressure medium discharge from the pressure chamber (35). relative to the drive element (22) is variable,

Wherein the pressure accumulator (43) has a displaceable element (45) which is provided with a first pressure surface (47) which partially delimits a reservoir (49),

Wherein the storage space (49) is connected to the pressure medium supply device (37),

• wherein by pressurizing the storage space (49), the displaceable element (45) against the force of an energy storage device (46) can be moved, characterized in that

The displaceable element (45) has at least one second pressure surface (48) which partially delimits a control space (50),

• wherein by pressurization of the control chamber (50), the displaceable element (45) against the force of the force accumulator (46) can be moved and

Wherein within the pressure accumulator (43) a flow of pressure medium from the reservoir (49) into the control chamber (50) is prevented.

2. Device (10) according to claim 1, characterized in that the control chamber (50) during operation of the internal combustion engine (1) optionally with a pressure source (38) or a tank (39) can be connected.

3. Device (10) according to claim 1, characterized in that the control chamber (50), without detour via a consumer, in a tank (39) can be emptied.

4. Device (10) according to claim 2, characterized in that control means (60) are provided, wherein the control chamber (50) by means of the control means (60) optionally with a tank (39) or the pressure source (38) can be connected.

5. Device (10) according to claim 2, characterized in that control means (60) are provided,

• lock in a first state a center of pressure IfI uss from the reservoir (49) to the pressure medium supply device (37) and a pressure medium flow to the reservoir (49) and the control chamber (50) allow and ® in another state, the pressure medium flow from the storage space (49) to the pressure medium supply device (37) and establish a connection between the control chamber (50) and a tank (39), without detour via a consumer.

6. Device (10) according to claim 5, characterized in that a supply line (51) is provided, which connects the pressure medium supply device (37) with the storage space (49) and a control line (52) is provided which the control chamber (50). connected to a pressure source (38).

7. Device (10) according to claim 6, characterized in that the control means (60) as a single-way valve (56) is formed, each having a connection (Ai, B ₁ , Pi, T ₁ , Vi,) for the supply Iiitung (51), the control line (52), the control chamber (50), the reservoir (49) and the tank (39).

8. Device (10) according to claim 6, characterized in that the control means (60) comprise at least a first directional control valve (53) which is arranged in the control line (52).

9. Device (10) according to claim 8, characterized in that the control means (60) further comprise a second directional control valve (57) or a entsperrba- res check valve (42e) which is arranged in the supply line (51).

10. Device (10) according to claim 8, characterized in that the control means (60) further comprise a pilot-operated check valve (42e) which is arranged in the supply line (51).

11.Vorrichtung (10) according to claim 5, characterized in that the storage space (49) and the control chamber (50) via a check valve (42 d) are connected, wherein the connection between the control means (60) and the spaces (49,50 ) and wherein the check valve (42d) blocks a pressure medium flow from the reservoir (49) to the control chamber (50).

12. Device (10) according to claim 1, characterized in that between the control chamber (50) and the pressure source (38), a check valve (42 b) is provided which a flow of pressure medium from the control chamber (50) in the direction of the pressure source (38). locks.

13. Device (10) according to claim 1, characterized in that between the reservoir (49) and the pressure medium supply means (37) a check valve (42c) is provided which a pressure medium flow from the pressure medium supply means (37) in the direction of the storage space (49). locks.

14. Device (10) according to claim 1, characterized in that a pressure medium loading of the storage space (49) the displaceable EIe- ment (45) moves in the same direction as a pressurizing of the control chamber (50).

15. Device (10) according to claim 1, characterized in that the displaceable element (45) has a third pressure surface (59) which at least partially delimits a counterpressure space (58), wherein a pressurization of the counterpressure space (58) the displaceable element (59). 45) displaces in the opposite direction as a Druckmitteibeauf- schlaguπg the control chamber (50) or the storage space (49).

16. Device (10) according to one of claims 2 or 5, characterized in that the ratio between the minimum flow cross section between the control chamber (50) and the tank (39) and the minimum flow cross section between the reservoir (49) and the Stelleinin- unit (10a, b) is greater than the ratio between the surface area of the second pressure surface (48) and the surface area of the first pressure surface (47).

17. Device (10) according to claim 1, characterized in that the storage space (49) and the control chamber (50) within the pressure accumulator

(43) do not communicate with each other.

18. Device (10) according to claim 4, characterized in that the control means (60) are designed as a directional control valve (53).