EP2459850B1 - Device for the variable adjusting of the control timing of gas exchange valves of an internal combustion engine - Google Patents

Description

Field of the invention

The invention relates to 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 and a volume accumulator, wherein the output element is rotatably arranged to the drive element, and the pressure chamber is at least partially limited by these components a phase position between the output element and the drive element is variably adjustable by pressure medium supply to or pressure fluid discharge from the pressure chamber, wherein pressure medium lines are provided, via which the pressure chamber pressure medium supplied or can be discharged therefrom, wherein the volume storage at least one housing and a movable therein separating element having a storage space communicating with one of the pressure medium lines, separated from a vented complementary space, wherein by pressure medium loading of the storage space, the separating element in such Housing is shifted, that the volume of the storage space increases at the expense of the Complementary space.

Background of the invention

In modern internal combustion engines devices for variable adjustment of the timing of gas exchange valves are used to the phase angle of a camshaft relative to a crankshaft in a defined angular range, between a maximum early and a maximum late position, variable to be able to shape. For this purpose, the device is integrated into a drive train, via which torque is transmitted from the crankshaft to the camshaft. This drive train can be realized for example as a belt, chain or gear drive.

Such a device is for example from the DE 10 2007 041 552 A1 known. The device comprises a phase adjusting device with a drive element, which is in driving connection with the crankshaft, and an output element, which is non-rotatably connected to the camshaft. In addition, the phase adjusting device comprises a plurality of pressure chambers, wherein each of the pressure chambers is divided by means of a wing into two counteracting pressure chambers. By supplying pressure medium to or pressure medium discharge from the pressure chambers, the wings are displaced within the pressure chambers, whereby a change in the phase position between the output element and the drive element takes place.

The pressure medium inflow to, or the pressure drain from the pressure chambers is controlled by means of a hydraulic circuit comprising a pressure medium pump, a pressure medium reservoir, a control valve, and a plurality of pressure medium lines. The control valve has a plurality of pressure medium connections, wherein 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, each with a group of oppositely acting pressure chambers.

During operation of the internal combustion engine acting on the camshaft alternating torques, which are caused by the rolling of the cams on each biased with a valve spring gas exchange valves. These torques are transmitted to the phase adjusting device and have a braking or accelerating effect on the adjustment speed of the phase position. In this case, during the opening of the gas exchange valve, a phase adjustment in the direction of later control times and during the closing of the gas exchange valve, a phase adjustment in the direction of early control times supported. During the phases in which the alternating torques times supported. During the phases in which the alternating torques support the phase adjustment, the pressure medium requirement of the phase adjusting device increases rapidly and can exceed the volume flow delivered by the pressure medium pump. In this case, the Phasenverstellgeschwindigkeit is not determined by the supporting alternating torque, but by the flow rate of the pressure medium pump. In this case, the supporting contribution of the alternating torques can not be fully exploited. This negative effect occurs all the more clearly, the smaller the pressure medium pump is dimensioned.

The publication DE102007056683 A1 discloses a similar device.

In order to ensure the function of the phase adjusting device, the pressure medium pump must deliver the volume flow required by the phase adjusting device in each operating phase of the internal combustion engine. For this purpose is in the DE 10 2007 041 552 A1 a volume accumulator is provided which communicates with the pressure medium line which connects the pressure medium pump with the control valve. In phases in which the pressure medium requirement of the phase adjusting device is less than the pressure medium volume delivered by the pressure medium pump, the volume reservoir is filled. In this case, a piston within a housing against an energy storage, in the illustrated embodiment, a compression spring, moved. In these phases, the energy storage is tensioned, ie the energy storage takes on an amount of energy that can be supplied to the hydraulic system again. If the system pressure drops, the volume accumulator empties into the hydraulic circuit under the influence of the relaxing force accumulator and thus supports the phase adjustment of the camshaft relative to the crankshaft.

A disadvantage of the illustrated embodiment is that, due to the tensioned compression spring, the emptying of the volume accumulator already begins at a time when the volume flow delivered by the pressure medium pump is sufficient to ensure the adjustment. The displaced in this phase from the volume memory pressure medium volume is no longer available in the phases of deficient supply of the phase adjusting device.

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, wherein the force acting on the phase control braking effect caused by pressure medium shortage supply should be minimized without having to size the pressure medium pump of the engine larger.

Solution of the task

The object is achieved in that the volume storage no energy storage, which is stretched when filling the pantry has.

The phase adjusting device is designed for example in the form of an impeller and has a drive element, which is driven for example by means of a Zugmittel- or gear drive by a crankshaft of the internal combustion engine. Furthermore, an output element is provided, which has a constant phase position to a camshaft, for example, by means of a frictional, cohesive or cohesive connection or screw rotatably connected thereto. The output element is rotatably arranged to the drive element and at least partially received in this. Within the phase adjusting device, at least one pressure chamber is provided. By supplying pressure medium to or pressure medium discharge from the pressure chamber, the relative phase position of the output element to the drive element and thus the camshaft can be adjusted to the crankshaft changeable. For this purpose, pressure medium lines are provided, via which the pressure chamber, for example with the interposition of a hydraulic control valve, can communicate with a pressure medium pump and a pressure medium reservoir of the internal combustion engine.

Alternatively, other embodiments of a phase adjusting device may be provided, for example phase adjusting device in Axialverstellerbauweise, in which an axially displaceable piston by pressure means cooperates by means of helical gears with the output element and the drive element. Such a phase adjusting device is for example from the DE 42 18 078 C1 known.

In addition, a volume accumulator is provided which has at least one housing and a separating element arranged inside the housing. The separator may be formed, for example, as a piston or non-elastic membrane and separates inside the housing a reservoir of a complementary space. In this case, the storage space communicates with one of the pressure medium lines, while the complementary space has a vent and, for example, communicates with the interior of the internal combustion engine. If the pressure medium line connected to the volume accumulator carries pressure medium, the supply chamber fills and the dividing element is displaced within the housing, so that the volume of the storage space is increased and the volume of the complementary space is reduced to the same extent. It can be provided that the complementary space has a vent opening, which communicates with the interior of the internal combustion engine. Thus, gas can escape from the complementary space, for example in the crankcase or the cylinder head of the internal combustion engine, so that no pressure builds up in the complementary space.

If a piston is used as a separating element, then this is displaced within the housing during filling of the volume accumulator. In the case of a membrane, this inverts in the direction of the complementary space.

Since no energy storage is provided, which is stretched during the filling of the volume memory, the filling takes place already at minimum operating pressures. In addition, the filled volume accumulator does not initially empty with decreasing pressure in the pressure medium line. Only when the pressure in the pressure medium line under the pressure which prevails in the complementary space and thus, for example, within the crankcase, drops, the reservoir is emptied into the pressure medium line. Thus, the entire volume of the volume memory of the phase adjusting device is only available from the time at which the pressure medium requirement is greater than the volume flow provided by the pressure medium pump. Thus, the on the camshaft acting alternating torques are used to a greater extent, which leads to significantly higher adjustment speeds.

During the standstill of the internal combustion engine no forces act on the separating element, so that it is freely displaceable. During operation of the internal combustion engine acts on the surface of the separating element, which limits the storage space, only a force which is determined by the pressure prevailing in the communicating with the reservoir pressure medium line. The surface of the separating element which delimits the complementary space is kept substantially powerless due to the venting. In particular, no force acts on this surface which increases with the degree of filling of the reservoir, which is the case with pressure retentate reservoirs. If the pressure in the pressure medium line, which communicates with the storage space, exceeds the atmospheric pressure (= pressure in the space with which the complementary space communicates), then the volume reservoir is filled. Only when the pressure in the pressure medium line drops below the atmospheric pressure, pressure medium is sucked from the volume storage in the pressure medium line and is thus available for phase adjustment. Thus, the separating element is displaced exclusively by the prevailing in the communicating with the volume storage pressure medium line pressure.

In a concretization of the invention it is provided that the device further comprises a control valve and at least a second pressure chamber which acts against the first pressure chamber and that a first pressure medium line communicates with the control valve and the first pressure chamber, that a second pressure medium line with the control valve and the second pressure chamber communicates and that a third pressure medium line communicates with the control valve and a pressure medium pump, wherein the reservoir communicates with the third pressure medium line.

In this embodiment, a pressure chamber is provided within the phase adjusting device, which is separated by a piston or a wing of an impeller into two oppositely acting pressure chambers. Each of the pressure chambers communicates via a pressure medium line with a working port of a control valve. In addition, another pressure medium line provided, which connects the pressure medium pump with an inlet port of the control valve. By means of the control valve, the pressure medium pump can be selectively connected to the first or second pressure chamber. At the same time, the other pressure chamber is connected to the pressure medium reservoir, so that the piston or the wing is displaced within the pressure chamber. This movement is converted directly or indirectly into an adjustment of the phase position of the output element relative to the drive element. Through the connection of the storage space to the pressure medium line, which connects the pressure medium pump with the control valve, the pressure medium is available both for adjusting operations in the direction earlier and for adjusting operations in the direction of later control times available. It is provided that the storage space between the control valve and the pressure medium pump opens into the third pressure medium line.

In addition, it can be provided that in the communicating with the reservoir pressure medium line upstream of a check valve and a check valve downstream of the volume memory is arranged, both check valves prevent backflow of pressure medium in the direction of the volume accumulator or the pressure medium pump. The check valves prevent pressure fluid from the pressure chambers to be filled, for example, the pressure chambers, which are connected to the inlet port of the control valve, flows back into the volume accumulator or to the pressure medium pump when due to the acting on the camshaft alternating torques arise in these pressure chambers pressure peaks. The pressure medium is thus supported on the check valves, whereby the Phasenverstellgeschwindigkeit increases and phase fluctuations are avoided.

The separating element may be formed, for example, as a piston. It can be made of plastic, for example, and additionally provided with stiffening ribs. Alternatively, the piston may be pot-shaped and made from a sheet metal blank. Also conceivable are disk-shaped pistons. The piston can separate the reservoir from the complementary space by means of a clearance fit in the housing. Alternatively, the Piston to be provided with a sealing element which cooperates sealingly with the housing.

In a development of the invention, it is provided that an end stop for the piston is provided in the complementary space. The end stop may be integrally formed with the housing or made separately therefrom. It can be provided that the contact surface of the end stop is smaller than the surface of the piston is formed, which limits the complementary space. Thus, it is prevented that the piston surface comes to rest on the housing or the end stop, whereby adhesion forces, which counteract an emptying of the volume memory can be reduced. The end stop may for example be formed circumferentially around a vent opening of the complementary space. In this case, the end stop can completely rotate around the vent opening or be formed with one or more interruptions.

The volume accumulator can be arranged, for example, within the internal combustion engine. In this case, gas and pressure medium from the complementary space can be vented directly into the interior of the internal combustion engine via a simple vent, additional seals are not necessary. Alternatively it can be provided that the volume accumulator is arranged outside the internal combustion engine, wherein a vent line is provided which communicate on the one hand with the complementary space and on the other hand with the interior of the internal combustion engine. The vent line can be formed for example in the housing of the volume memory or an additional housing which encapsulates the volume memory. In this embodiment, seals are provided which seal the vent line and the connection between the reservoir and the pressure medium line to the environment.

The volume accumulator can be connected, for example by means of a thread formed on this with the cylinder head, the crankcase or any other surrounding construction. Advantageously, the thread comprises an opening through which the storage space communicates with the pressure medium line.

In a concretization of the invention it is provided that the volume accumulator is arranged within a camshaft. Thus, the volume accumulator can be integrated into the internal combustion engine without the space requirement of the internal combustion engine. Furthermore, this realizes a minimum distance between the volume memory and the phase adjusting device and thus improves the response. In this case, the inner wall of the camshaft can serve as a housing in which the separating element is received.

Brief description of the drawings

Figur 1

nur sehr schematisch eine Brennkraftmaschine,

Figur 2

eine erfindungsgemäße Vorrichtung, wobei die Phasenstelleinrichtung in einer Draufsicht und der Hydraulikkreislauf schematisch dargestellt sind,

Figur 3

einen Längsschnitt durch die Phasenstelleinrichtung aus Figur 2 entlang der Linie III-III,

Figur 4

eine Darstellung des auf die Nockenwelle wirkenden Wechseldrehmoments,

Figur 5

eine erste Ausführungsform eines Volumenspeichers,

Figur 6

eine zweite Ausführungsform eines Volumenspeichers,

Figur 7

eine dritte Ausführungsform eines Volumenspeichers,

Figur 8

eine vierte Ausführungsform eines Volumenspeichers.

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

only very schematically an internal combustion engine,

FIG. 2

a device according to the invention, wherein the phase adjusting device is shown schematically in a plan view and the hydraulic circuit,

FIG. 3

a longitudinal section through the phase adjusting device FIG. 2 along the line III-III,

FIG. 4

a representation of the force acting on the camshaft alternating torque,

FIG. 5

a first embodiment of a volume memory,

FIG. 6

a second embodiment of a volume memory,

FIG. 7

a third embodiment of a volume memory,

FIG. 8

a fourth embodiment of a volume memory.

Detailed description of the drawing,

In FIG. 1 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 11 for a relative rotation between the crankshaft 2 and the camshafts 6, 7 can provide. Cams 8 of the camshafts 6, 7 actuate one or more inlet gas exchange valves 9 or one or more Auslassgaswechselventile 10. Likewise, it may be provided only one of the camshafts 6, 7 with a device 11, or provide only a camshaft 6, 7, which with a Device 11 is provided.

The FIGS. 2 and 3 show a first embodiment of a device 11 according to the invention, wherein a phase adjusting device 11a in a plan view or in cross section and the hydraulic circuit are shown schematically. The phase adjusting device 11a has a drive element 13 and an output element 14. On the axial side surfaces of the drive member 13, a side cover 15 is rotatably mounted in each case. The output element 14 is designed in the form of an impeller and has a substantially cylindrically designed hub member 16, extend from the outer cylindrical surface in the illustrated embodiment, five wings 17 in the radial direction outwards. The vanes 17 are formed separately from the output element 14 and arranged in vane grooves of the hub element 16. The wings 16 are acted upon by means of wing springs 18, which are arranged between the Nutgründen the vane grooves and the wings 17, radially outwardly with a force.

Starting from an outer peripheral wall 19 of the drive element 13, a plurality of projections 20 extend radially inwardly. In the illustrated embodiment, the projections 20 are formed integrally with the peripheral wall 19. The drive element 13 is mounted by means of radially inner circumferential walls of the projections 20 relative to the output element 14 rotatably mounted on this.

On an outer circumferential surface of the drive element 13, a sprocket 12 is arranged, by means of which a torque transmission from the crankshaft 2 to the drive element 13 can be transmitted via a chain drive, not shown.

Within the phase adjusting device 11 a between each two circumferentially adjacent projections 20, a pressure chamber 21 is formed. Each of the pressure chambers 21 is circumferentially bounded by opposite, in the Wezeitlichen radially extending boundary walls 22 adjacent projections 20, in the axial direction of the side covers 15, radially inwardly of the hub member 16 and radially outwardly from the peripheral wall 19. In each of the pressure chambers 21 protrudes a wing 17, wherein the wings 17 are formed such that they rest against both the side covers 15, and on the peripheral wall 19. Each wing 17 thus divides the respective pressure chamber 21 into two oppositely acting pressure chambers 23, 24th

The output element 14 is received in the drive element 13 and rotatably supported in a defined Winkelbreich to this. The angular range is limited in one direction of rotation of the driven element 14 in that the wings 17 come into contact with a corresponding boundary wall 22 (early stop 22a) of the pressure chambers 21. Similarly, the angular range in the other direction of rotation is limited by the fact that the wings 17 come to rest on the other boundary walls 22 of the pressure chambers 21, which serve as a late stop 22b.

By pressurizing a group of pressure chambers 23, 24 and Pressure relief of the other group, the phase angle of the output member 14 can be varied relative to the drive member 13. By pressurizing both groups of pressure chambers 23, 24, the phase position can be kept constant. Alternatively, it may be provided that none of the pressure chambers 23, 24 are subjected to pressure medium during phases of constant phase position. 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 23, 24, a hydraulic circuit 25 is provided which comprises a pressure medium pump 26, a pressure medium reservoir 27, a control valve 28 and a plurality of pressure medium lines 25a, b, p. The control valve 28 has an inlet connection P, a tank connection T and two working connections A, B. The first pressure medium line 25a connects the first working port A with the first pressure chambers 23. The second pressure medium line 25b connects the second working port B with the second pressure chambers 24. The third pressure medium line 25p connects the pressure medium pump 26 with the inflow port P.

Pressure medium conveyed by the pressure medium pump 26 is supplied to the feed port P of the control valve 28 via the third pressure medium line 25p. Depending on the control state of the control valve 28, the inlet connection P is connected to the first pressure medium line 25a, the second pressure medium line 25b or to both or none of the pressure medium lines 25a, b.

In order to shift the control times (opening and closing times) of the gas exchange valves 9, 10 in the direction early, the pressure medium supplied to the control valve 28 via the third pressure medium line 25p via the first pressure medium line 25a to the first pressure chambers 23. At the same time, pressure medium from the second pressure chambers 24 reaches the control valve 28 via the second pressure medium line 25b and is ejected into the pressure medium reservoir 27. As a result, the wings 17 are displaced in the direction of the early stop 22a, whereby a rotary movement of the output element 14 relative to the drive element 13 in the direction of rotation of the phase adjusting device 11a is achieved.

In order to shift the timing of the gas exchange valves 9, 10 toward late, the pressure medium supplied to the control valve 28 via the third pressure medium line 25p via the second pressure medium line 25b to the second pressure chambers 24 is passed. At the same time, pressure medium from the first pressure chambers 23 reaches the control valve 28 via the first pressure medium line 25a and is ejected into the pressure medium reservoir 27. As a result, the wings 17 are displaced in the direction of the late stop 22b, whereby a rotary movement of the output element 14 relative to the drive element 13 against the direction of rotation of the phase adjusting device 11a is achieved.

In order to keep the control times constant, the pressure medium supply to all pressure chambers 23, 24 is either prevented or permitted. As a result, the wings 17 are hydraulically clamped within the respective pressure chambers 21, and thus prevents a rotational movement of the output element 14 relative to the drive element 13.

During operation of the internal combustion engine 1, the camshaft 6, 7 rotates about its longitudinal axis. Each gas exchange valve 9, 10 is periodically opened against the force of a valve spring 30 and closed again. During the opening phase of the gas exchange valve 9, 10 (auflaufender cam) acts on the camshaft 6, 7, a braking torque, which corresponds to the vector product of the force of the valve spring 30 with the lever arm of the cam 8. During the closing of the gas exchange valve 9, 10 (expiring cam) acts on the camshaft 6, 7 an accelerating torque, which corresponds to the vector product of the force of the valve spring 30 with the lever arm of the cam 8. Thus acts on the camshaft 6, 7, a periodic alternating torque M, in FIG. 4 is plotted against the crankshaft angle α.

During a phase adjustment toward later (earlier) control times the in FIG. 4 represented positive (negative) share of the alternating torque M, the phase adjustment. In this case, the output element 14 is both by the system pressure provided by the pressure medium pump 26, as well as by the positive (negative) share of the alternating torque M in the direction later (earlier) adjusted timing and thus increases the Phasenverstellgeschwindigkeit. In internal combustion engines 1 with high alternating torques M, this can lead to the adjustment process induced by the alternating torques M occurring at such high speeds that the pressure medium volume delivered by the pressure medium pump 26 is insufficient to sufficiently accommodate the expanding second (first) pressure chambers 24 (23) to supply with pressure medium. As a result, in the second (first) and third pressure medium line 25b (a), p, a negative pressure, which counteracts the adjustment process. Thus, the acting on the camshaft 6, 7 alternating torques M not be optimally used, but are effective only up to a limiting torque M. ₁

At the same time, the negative (positive) portion of the alternating torque M counteracts the phase adjustment. If the negative (positive) portion of the alternating torque M exceeds the torque generated by the pressure medium pump 26, pressure medium is displaced from the second (first) pressure chambers 24 (23) back into the second (first) and third pressure medium lines 25b (a), p For a short time a phase adjustment against the desired direction.

In order to prevent this, the pressure medium pump 26 can be dimensioned correspondingly larger, whereby the space requirement, the cost and the fuel consumption of the internal combustion engine 1 are increased.

Alternatively, according to the invention, a volume accumulator 31 may be provided. FIG. 5 shows a possible embodiment of the volume memory 31, which is arranged within the internal combustion engine 1. This comprises a housing 32 in which a separating element 33 is arranged freely displaceable. The partition 33 is formed in the illustrated embodiment as a piston which divides the housing 32 into a reservoir 34 and a complementary space 35. The piston carries a sealing element 38, which seals the two spaces against each other. The reservoir 34 opens between two (optional) check valves 29 in the third pressure medium line 25p. The complementary space 35 communicates via a vent opening 36 with the interior of the internal combustion engine 1.

If the pressure in the third pressure medium line 25p exceeds the pressure prevailing in the interior of the internal combustion engine 1, the piston is displaced in the direction of an end stop 37 by the pressure medium flowing into the housing 32. Thus, the volume of the reservoir 34 increases at the expense of the volume of the complementary space 35 until the piston abuts the end stop 37 ( FIG. 5 , upper illustration of the volume memory 31). At the same time, the gas present in the complementary space 35 can escape via the vent opening 36 into the interior of the internal combustion engine 1.

In contrast to the known from the prior art Druckfeder- or bladder memory here no power storage is provided, for example, a compression spring or a compressible gas cushion, which is stretched during the filling. In this case, the volume memory 31 is arranged such that the displacement of the separating element 33 is perpendicular to gravity. Thus, the force of gravity does not act in the direction of displacement of the separating element 33, whereby the volume memory 31 is not emptied even during the stoppage of the internal combustion engine 1.

The volume memory 31 reaches its fully filled state even at low system pressures. In addition, there is no automatic emptying of the volume memory 31 at decreasing system pressure in the third pressure medium line 25 p, as long as the pressure is greater than or equal to the pressure prevailing in the interior of the internal combustion engine 1 pressure.

Acts on the camshaft 6, 7 a phase adjustment assisting alternating torque M, pressure medium from the first and second pressure medium line and the third pressure medium line 25a, b, p is sucked into the expanding pressure chambers 23, 24, whereby the pressure in these pressure medium lines 25a, b, p drops below the pressure which prevails within the internal combustion engine 1. As a result, the pressure medium volume stored in the reservoir 34 is drawn into the third pressure medium line 25p, and further to the respective pressure chambers 23, 24. In this case, the piston is displaced within the housing 32 in the direction of the outlet opening of the storage space 34 ( FIG. 5 , bottom view of the volume memory 31). Thus, the phase adjusting device 11a is an additional pressure medium volume available, which is mobilized only when that of the Pressure medium pump 26 funded pressure medium volume is smaller than the pressure medium volume, which is required for the induced by the alternating torque M phase adjustment. Thus, the maximum usable limit torque M ₂ and thus the Phasenverstellgeschwindigkeit is significantly increased. If the alternating torque M acting on the camshaft 6, 7 acts against the phase adjustment direction, then the check valves 29 prevent pressure fluid from the pressure chambers 23, 24 from being expelled into the volume accumulator 31 or into the hydraulic circuit 25, the pressure medium resting on the check valves 29 from.

Thus, the assisting portion of the alternating torque M is utilized to a greater extent to increase the Phasenverstellgeschwindigkeit and intercepted the counteracting portion. The emptying of the volume accumulator 31 on the basis of the freely displaceable piston (i.e., the lack of force accumulator) begins only when the pressure medium volume delivered by the pressure medium pump 26 is smaller than the required pressure medium volume.

In this embodiment, the piston is formed as a cylindrical member and may consist of a metallic material or a suitable plastic. The end stop 37 runs around the vent opening 36, wherein the piston-facing surface is smaller than the piston surface is formed in order to reduce adhesion forces.

FIG. 6 shows a second embodiment of a volume memory 31 of a device 11 according to the invention. In contrast to the first embodiment, the piston is cup-shaped and made by means of a deep-drawing process of a sheet metal part. The seal between the reservoir 34 and the complementary space 35 via a tightly tolerated sealing gap between the outer surface of the piston and the inner circumferential surface of the housing 32. The end stop 37 is formed integrally with the housing 32. Likewise conceivable are embodiments in which the end stop 37 is manufactured as a separate component and fixed in the housing 32. In this case, the separate end stop 37 may be formed as a sealing ring, whereby the sealing effect between the piston and the housing 32 increases is when the volume memory 31 is completely filled.

The housing 32 has a pin 40 with a through hole, which opens on the one hand into the reservoir 34 and on the other hand into the third pressure medium line 25p. By means of a formed on the outer circumferential surface of the pin 40 thread, the housing 32 is attached to a surrounding structure 42, such as a cylinder head or a crankcase.

FIG. 7 shows a third embodiment of a volume memory 31 of a device 11 according to the invention. In contrast to the first embodiment, the end stop 37 is interrupted in the circumferential direction by recesses 39, whereby the contact surface between the piston and end stop 37 and thus acting between these components adhesion forces are further reduced. The piston consists in this embodiment of a suitable plastic and may be provided with stiffening ribs.

FIG. 8 shows a fourth embodiment of a volume memory 31 of a device 11 according to the invention. In contrast to the previous embodiments, this volume memory 31 is arranged outside of the internal combustion engine 1. The housing 32 has a pin 40 with a through hole, which opens on the one hand into the reservoir 34 and on the other hand into the third pressure medium line 25p. The housing 32 is encapsulated by a second housing 41, which is fastened to the cylinder head 42 by means of a screw connection. Within the second housing 41, a vent line 43 is formed, by means of which the complementary space 35 communicates with the interior of the internal combustion engine 1. Thus, gas and pressure medium from the complementary space 35 can be passed into the interior of the internal combustion engine 1 when the piston is moved in the direction of the end stop 37. At the contact surface between the cylinder head 42 and the first and second housing 31, 41 sealing rings 44 are provided to prevent the escape of pressure medium. Likewise conceivable are embodiments in which only a thick-walled housing 31 is provided, in which the vent line 43 is formed.

reference numeral

1

Internal combustion engine

2

crankshaft

3

piston

4

cylinder

5

traction drive

6

intake camshaft

7

exhaust

8th

cam

9

Inlet gas exchange valve

10

Auslassgaswechselventil

11

contraption

11a

Phase adjustment device

12

Sprocket

13

driving element

14

output element

15

side cover

16

hub element

17

wing

18

wing feather

19

peripheral wall

20

head Start

21

pressure chamber

22

boundary wall

22a

early stop

22b

late stop

23

first pressure chamber

24

second pressure chamber

25

Hydraulic circuit

25a

first pressure medium line

25b

second pressure medium line

25p

third pressure medium line

26

Hydraulic pump

27

Pressure fluid reservoir

28

control valve

29

check valve

30

valve spring

31

volume storage

32

casing

33

separating element

34

pantry

35

complementary space

36

vent

37

end stop

38

sealing element

39

recess

40

spigot

41

second housing

42

adjacent construction

43

vent line

44

seal

A

first work connection

B

second work connection

P

inflow connection

T

drain connection

α

crankshaft angle

M

alternating torque

M ₁ , M ₂

limit torque

Claims (12)

1. Device (11) for variably setting the control timing of gas exchange valves (9, 10) of an internal combustion engine (1), having

   - a drive element (13), an output element (14), at least one pressure chamber (23) and a volume accumulator (31),

   - wherein the output element (14) is arranged so as to be rotatable with respect to the drive element (13), and the pressure chamber (23) is bounded at least partially by these components (13, 14),

   - wherein a phase angle between the output element (14) and the drive element (13) can be set variably by supplying pressure medium or discharging pressure medium to or from the pressure chamber (23),

   - wherein pressure medium lines (25a, b, p) are provided via which pressure medium can be fed to the pressure chamber (23) or discharged therefrom,

   - wherein the volume accumulator (31) has at least one housing (32) and a dividing element (33) which can be moved therein and which divides a reservoir space (34), which communicates with one of the pressure medium lines (25a, b, p), from the vented complementary space (35),

   - wherein by applying pressure medium to the reservoir space (34) the dividing element (33) is moved in the housing (32) in such a way that the volume of the reservoir space (34) increases at the expense of the complementary space (35),

   - characterized in that the volume accumulator (31) does not have an energy accumulator which is tensioned when the reservoir space (34) is filled.
2. Device (11) according to Claim 1, characterized in that the dividing element (33) is moved exclusively by the pressure present in the pressure medium line (25a, b, p) which communicates with the volume accumulator (31).
3. Device (11) according to Claim 1, characterized in that the complementary space (35) has a venting opening (36) which communicates with the interior of the internal combustion engine (1).
4. Device (11) according to Claim 1, characterized in that the device (11) also has a control valve (28) and at least one second pressure chamber (24) which acts counter to the first pressure chamber (23), and in that a first pressure medium line (25a) communicates with the control valve (28) and the first pressure chamber (23), in that a second pressure medium line (25b) communicates with the control valve (28) and the second pressure chamber (24), and in that a third pressure medium line (25p) communicates with the control valve (28) and a pressure medium pump (26), wherein the reservoir space (34) communicates with the third pressure medium line (25p).
5. Device (11) according to Claim 1, characterized in that in the pressure medium line (25a, b, p) which communicates with the reservoir space (34), a non-return valve (29) is arranged upstream, and a non-return valve (29) is arranged downstream, of the volume accumulator (31), wherein the two non-return valves (29) prevent a return flow of pressure medium in the direction of the volume accumulator (31) or of the pressure medium pump (26).
6. Device (11) according to Claim 1, characterized in that the dividing element (33) is embodied as a piston.
7. Device (11) according to Claim 6, characterized in that the piston is embodied in a pot shape and is manufactured from a sheet-metal blank.
8. Device (11) according to Claim 6, characterized in that an end stop (37) for the piston is provided in the complementary space (35).
9. Device (11) according to Claim 8, characterized in that the bearing surface of the end stop (37) is made smaller than the area of the piston which bounds the complementary space (35).
10. Device (11) according to Claim 8, characterized in that the end stop (37) is embodied so as to run around a venting opening (3.6) in the complementary space (35).
11. Device (11) according to Claim 1, characterized in that the volume accumulator (31) is arranged inside the internal combustion engine (1).
12. Device (11) according to Claim 1, characterized in that the volume accumulator (31), is arranged outside the internal combustion engine (1), wherein a venting line (43) is provided which communicates at one end with the complementary space (35) and at the other end with the interior of the internal combustion engine (1).

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