KR20100093528A - Apparatus for variably adjusting the control times of gas exchange valves in an internal combustion engine - Google Patents

Abstract

An apparatus for variably adjusting 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 supply device allows pressurized medium to be fed to or discharged from the pressure chamber. A phase angle of the output element relative to the input element can be changed by feeding 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 or can be connected to the supply device. An energy store applies a force to the movable element in the direction of an initial position. The movable element can be moved against the force of the energy store by pressurizing the storage space.

Description

Apparatus for variablely adjusting the control time of the gas exchange valve of an internal combustion engine {APPARATUS FOR VARIABLY ADJUSTING THE CONTROL TIMES OF GAS EXCHANGE VALVES IN AN INTERNAL COMBUSTION ENGINE}

The present invention relates to an apparatus for varying the control time of gas exchange valves of an internal combustion engine, comprising a drive member, an output member, one or more pressure chambers, a pressure medium supply device, and one or more pressure accumulators. By means of the pressure medium supply device, a pressure medium may be supplied to or discharged from the pressure chamber, or the pressure medium may be supplied to or discharged from the pressure chamber. The phase position of the output member can vary, and the pressure accumulator includes a displaceable member having a first pressure surface that partially limits the storage space, in which case the storage space can be connected or connected to the pressure medium supply device, The energy accumulator applies a force in the direction of the starting position to the displaceable member. In this case, the displaceable member can be displaced against the force of the energy accumulator by applying pressure to the storage space.

In modern internal combustion engines, in order to be able to variably construct the phase relationship between the crankshaft and the camshaft in a defined angular range, i.e. between the maximum advance position and the maximum retard position, An apparatus for varying the control time of the exchange valves is used. Such a device typically includes an actuating device which is driven by the crankshaft and transmits the torque of the crankshaft to the camshaft. Here, inside the actuating device, a hydraulic actuator is formed which allows to influence the phase position between the crankshaft and the camshaft as desired. A pressure medium supply device is provided for supplying pressure medium to the operating device.

Devices of the aforementioned type are known, for example, from EP 1 025 343 B1. The device comprises two rotors that are rotatable with each other, wherein the outer rotor is driven in connection with the crankshaft, and the inner rotor is connected in a non-rotatable manner with the camshaft. The apparatus comprises a plurality of hollow spaces, each of which is divided by vanes into two interacting pressure chambers. The vanes are displaced inside the pressure chambers by supplying pressure medium to the pressure chambers or withdrawing the pressure medium from the pressure medium, whereby the rotation of the rotors and thus the rotation of the camshaft about the crankshaft as desired. Is done.

Supplying or evacuating the pressure medium to the pressure chambers is controlled by a pressure medium supply device comprising a pressure medium pump, a tank, a control valve and a plurality of pressure medium lines. In this connection the pressure medium line connects the pressure medium pump to the control valve. Each additional pressure medium line connects one of the working ports of the control valve to the pressure chambers. The pressure medium is typically provided from the lubricating oil circuit of the internal combustion engine.

To ensure the function of the device, the pressure in the pressure medium system must exceed a certain value in each operating stage of the internal combustion engine. This is particularly important in the idling stage of the internal combustion engine, since the pressure medium pump is driven by the crankshaft and thereby the system pressure rises with the speed of the internal combustion engine. In addition, the system pressure supplied by the pressure medium pump depends on the pressure medium temperature, that is, the system pressure drops as the temperature rises. Therefore, the pressure medium pump should be configured in such a way that the pressure medium pump can provide sufficient system pressure in the worst condition so that the phase position of the inner rotor relative to the outer rotor can be adjusted quickly enough. The pressure medium pump must be configured accordingly so as to ensure the required speed of adjustment in the worst pressure conditions, such as high pressure medium temperatures and / or low rotational speeds. As a result, pressure medium pumps are used, which are configured to meet the maximum requirements of the actuating device so that the size is set too large of most of the operating stages of the internal combustion engine. According to an alternative embodiment to this an adjustable pressure medium pump can be used which provides the pressure medium as required. The increased complexity in these two cases negatively impacts the cost, mounting space requirements and fuel consumption of the internal combustion engine.

Such a device is also known in another form in US Pat. No. 5,775,279 A. According to an embodiment of this publication, a pressure accumulator connected to the pressure medium supply device is arranged between the pressure medium pump and the control valve. This pressure accumulator is filled with a pressure medium at high system pressure levels. If the system pressure drops, the pressure accumulator is emptied automatically, thereby providing additional pressure medium to the pressure medium supply. As a result, phase adjustment of the device is supported. Disadvantages of this embodiment include the situation where the pressure accumulator is emptied when the system pressure drops not on the basis of the adjustment process but on the basis of another external situation, for example by deceleration of the rotational speed. As such, lower pressure support and smaller pressure medium volume are provided from the pressure accumulator for subsequent phase adjustment procedures. A further disadvantage is that the maximum pressure that the pressure accumulator can support the pressure medium supply corresponds to the pressure present in the pressure medium supply just before the phase adjustment process. If the adjustment request is sent from the engine control unit to the device at high temperature and low rotational speed conditions, the pressure support of the pressure accumulator is less because the system pressure that was filled in the pressure accumulator was low. As a result, the adjustment process may not be carried out or the speed of adjustment may be significantly reduced. Therefore, even in this case, the pressure medium pump must be configured to meet the peak load which results in disadvantages.

It is an object of the present invention to provide a device for variably adjusting the control time of gas exchange valves of an internal combustion engine, so that safe adjustment of the control time is ensured even at high regulation speed conditions in each operating stage of the internal combustion engine. Another object is to allow the pressure medium pump to be set to an oversize (a configuration that matches the expected peak load), just as the use of a variable pressure medium pump is excluded.

This object is achieved according to the invention by the displaceable member comprising a back pressure surface that at least partially restricts the back pressure space, in which case the displaceable member can be displaced in the direction of the starting position by supplying a pressure medium to the back pressure space. have. The displaceable member may be formed as, for example, a pressure piston that can be displaced in the pressure tank against the force of an energy accumulator formed as a spring member, for example. When the pressure medium is supplied to the storage space, the volume of the storage space increases the cost for the back pressure space. If the system pressure in the pressure medium supply drops, the force of the energy accumulator exceeds the force caused on the first pressure surface due to the system pressure. The pressure piston is thereby pressurized by the energy accumulator to a starting position with a minimum volume of storage space.

As an alternative to the spring member, it is also possible to use other forms of energy accumulators, such as for example reversible deformable bodies made of elastomer, or gas filled gas pockets. When the pressure medium is supplied to the back pressure space during the operating stage of the internal combustion engine where the pressure accumulator must deliver the pressure medium to the pressure medium supply device, in addition to the force of the energy accumulator on the displaceable member, an additional force is applied to the starting position in the direction of the starting position. Power of work. This additional force is formed from the pressure in the back pressure chamber acting on the back pressure surface. For the value F, F = pA _G is applied, in which p corresponds to the pressure acting on the back pressure surface, and A _G corresponds to the area of the back pressure surface.

As the pressure provided from the pressure accumulator rises, the pressure accumulator can resist peak consumption, so the pressure medium pump can be designed for normal operation of the internal combustion engine. To ensure safe and fast phase positioning, it is not necessary to oversize or adjust the pressure medium pump. In addition, the adjusting speed of the operating device increases. Alternatively, the operating device can be set smaller if the adjustment speeds are the same. Thus, mass, mass moment of inertia and cost can be reduced.

In an improvement of the invention, the displaceable member comprises at least one second pressure surface which partially limits the control space, the displaceable member being displaced against the force of the energy accumulator by applying pressure to the control space and The pressure medium flow from the storage space to the control space in the pressure accumulator is inhibited. Moreover, the storage space and the control space may not be connected to each other in the pressure accumulator. Preferably, the displaceable member is displaced in the same direction as when the pressure medium is supplied to the control space by supplying the pressure medium to the storage space, preferably in a direction away from the starting position of the displaceable member.

By forming a pressure accumulator that includes a displaceable member that partially limits the pressure spaces that are isolated from each other within the pressure accumulator, the two pressure spaces can be controlled separately from each other, that is, filled and / or Can be emptied. There is no connection between the pressure spaces except for leaks. Thus, for example, various pressure sources can be used for filling the storage space and the control space. According to an alternative embodiment, a pressure medium connection between the storage space and the control space may be provided inside the pressure accumulator. The pressure medium supplied to the control space can reach the storage space via the pressure medium connection. In this case, however, it must be ensured that a pressure medium flow reverses from the storage space to the control space. This can be realized, for example, via a pressure medium channel provided inside a pressure tank or pressure piston of the pressure accumulator and in which a check valve is arranged. In this case, the filling of the storage space and the control space can be made only by filling the control space. And if the pressure accumulator has to be emptied, the control space is connected to the tank. The storage space is emptied into the pressure medium supply device, and the control space is emptied into the tank and becomes pressureless. Overflow of the pressure medium, which can be made from the storage space to the control space, is prevented by the check valve. If the displaceable member is displaced in the same direction as when the pressure medium is supplied to the control space by supplying the pressure medium to the storage space, the control space can support the filling of the storage space. For this purpose, the control space is likewise filled with a pressure medium during the filling process of the storage space. This forces one force on the two pressure planes of the pressure piston to act on the two pressure planes, whereby a larger force is stored in the energy accumulator (the spring member is compressed more strongly). If the filled pressure accumulator is commanded by the engine control unit to support the phase adjustment process, the control space can be emptied regardless of the storage space. In other words, while the storage space is emptied into the pressure medium supply, the control space can be vented into the tank against atmospheric pressure to support the phase adjustment process. With a suitable configuration, the air discharge of the control space can be made faster than the storage space is emptied into the pressure medium supply. This causes all forces stored in the energy accumulator to act on the storage space through the first pressure surface. As a result, the pressure may rise by a factor of up to the following equation depending on the load acting on the energy accumulator at that point at the start of the support process.

)만큼 상승한다.In the above formula, A ₁ corresponds to the area of the first pressure surface and A ₂ corresponds to the area of the second pressure surface. If, for example, a spring member is used as the energy accumulator, the pressure is at the start of the support process, as long as the spring has not yet reached its maximum compressed state.

Rise by)

In a refinement of the invention the back pressure space can be selectively connected to a pressure source or to a tank. Control means may be provided, in which case the back pressure space can be selectively connected to the tank or to the pressure source by the control means. The back pressure space may be connected to the pressure medium pump of the internal combustion engine. The back pressure space may be connected to the tank of the internal combustion engine.

The pressure source may be, for example, a pressure medium supply device or a pressure medium pump of the pressure medium supply device, or may be a pressure source independent of the pressure source, for example, a servo consumer (eg, a power steering system). In this case, in the case of the pressure source of the servo-consuming device, the pressure accumulator can be completely filled even in the operating stage indicating low system pressure. The selective connection with the pressure source or tank is via control means, for example via a 3 / 2-way control valve in the form of a switching valve (eg seat valve) or a proportional valve (eg slide valve). According to an alternative embodiment two control means are contemplated, wherein one of the control means blocks or opens the connection from the pressure source to the back pressure space, and the other control means blocks the connection from the back pressure space to the tank. Or open. The control means may be an electromagnetically actuated hydraulic valve, for example a directional control valve (eg a switching or proportional valve), or a check valve which may be released. Such control means receive control signals from the engine control unit of the internal combustion engine, which determine whether the back pressure space is filled or emptied, i.e. whether the pressure accumulator is to be filled or the emptying process is to be supported. . Similarly, the use of hydraulic actuation control means may be considered. In this case, the hydraulic actuating device of the control means can be connected to the pressure medium supply device. The control means can thus automatically switch to below the specified value when the pressure in the pressure medium supply drops. This significantly reduces the regulatory complexity.

If the tank of the internal combustion engine and / or the pressure medium pump are used for filling or evacuating the back pressure space, no additional parts other than those already present in the internal combustion engine are needed. There is also a lower demand for a seal between the pressure medium tank and the pressure piston, because mixing of the pressure medium in the storage space and back pressure space is allowed. Thereby the sealing member acting between the pressure piston and the pressure tank can be omitted.

It can also be presented that a directional control valve comprising a pressure source, a tank and one port each connected to the back pressure space is provided as control means. In a refinement of the invention further ports may be provided connected to the storage space or the control space.

The pressure support of the pressure accumulator can be activated through simple switching of one or more control means. In this regard, in the operating stages of the internal combustion engine where the phase position is kept constant, the pressure medium volume accumulates in the storage space is supplied. Pressure support of the pressure accumulator may be used during each phase adjustment process. For this purpose, whenever a phase adjustment is required, the control means (direction control valve and / or check valve which can be released) move to the position where the storage space is emptied. The pressure accumulator can be filled in the operating stage between phase adjustment requests. There is also another possibility of providing pressure support of the pressure accumulator as needed. If the engine control unit detects that the pressure or volume flow supplied from the pressure medium pump is not sufficient for phase adjustment, the engine control unit allows for pressure support through the pressure accumulator. This measure extends the time that the pressure accumulator can be filled, thus increasing the performance of the pressure accumulator during pressure support. According to an alternative embodiment to this, the pressure support of the pressure accumulator can only be used as a "boost" function for a critical adjustment process that requires, for example, high volume flow or high adjustment speed. If at the engine control unit it is detected that the threshold adjustment process should be guided, the engine control unit activates the pressure support through appropriate adjustment of the control means.

It is likewise conceivable to form the control means as a single member with a control valve which controls the pressure medium flow directed to or exiting the pressure chambers of the actuating device.

Preferably the maximum volume of the storage space corresponds to at least twice the volume required for phase adjustment from the maximum perceptual position to the maximum advance position.

The pressure accumulator may for example be introduced into the pressure medium line between the pressure medium pump and the control valve. According to an alternative embodiment the pressure accumulator can be introduced into the pressure medium line, which connects one of the operating ports of the control valve to one of the pressure chambers of the one side of the pressure medium lines. In addition to this embodiment, a second pressure accumulator may be provided which flows into the pressure medium line connecting the other actuation port of the control valve to the pressure chambers of the other group.

Further features of the invention are presented in the following detailed description and in the drawings, in which embodiments of the invention are schematically illustrated.
1 is a schematic diagram showing only an internal combustion engine very schematically.
2A is a longitudinal cross-sectional view of the actuating device.
2b is a cross-sectional view of the actuating device.
3 is a view of a first embodiment of the device according to the invention.
4 is a view of a second embodiment of the device according to the invention.
5 is a diagram of a third embodiment of an apparatus according to the invention.

1 shows a schematic representation of an internal combustion engine 1 and a piston 3 seated on the crankshaft 2 in the cylinder 4. The crankshaft 2 is connected to the intake camshaft 6 or the exhaust camshaft 7, respectively, via one traction drive 5 according to the illustrated embodiment, and the first and second devices 10 are It is possible to provide relative rotation between the crankshaft 2 and the camshafts 6, 7. The devices 10 each comprise one hydraulic actuating device 10a, b and a pressure medium supply device 37. The cams 8 of the camshafts 6, 7 actuate one or more intake gas exchange valves 9a or one or more exhaust gas exchange valves 9b. Similarly, the device 10 may be mounted only on one of the camshafts 6, 7, or may be provided with only one camshaft 6, 7 on which the device 10 is mounted.

3 shows a first embodiment of a device 10 according to the invention with actuating devices 10a, b, a pressure medium supply device 37, and a pressure accumulator 43. 2a and 2b show the actuating devices 10a and b respectively in longitudinal and cross sectional views. The actuating devices 10a and b comprise a drive member formed as the outer rotor 22 and an output member formed as the inner rotor 23. The outer rotor 22 comprises a housing 22a and two side covers 24, 25 arranged on the axial side of the housing 22a. The inner rotor 23 is embodied in the form of an impeller and comprises a hub member 26 which is substantially cylindrical in shape. From the outer cylindrical circumferential surface of the hub member five vanes 27 are shown in the embodiment shown. It extends outward in the radial direction. The vanes 27 are formed independently toward the inner rotor 23 and are disposed in the vane groove 28 formed in the hub member 26. The vanes 27 are energized outwardly in the radial direction by vane springs 27a respectively disposed between the groove bottoms of the vane grooves 28 and the vanes 27.

The plurality of protrusions 30 extend inwardly in the radial direction starting from the outer circumferential wall portion 29 of the housing 22a. According to the embodiment shown, the protrusions 30 are formed of a single member together with the circumferential wall 29. The outer rotor 22 is supported on this inner rotor rotatably with respect to the inner rotor 23 by such circumferential wall portions located radially inward as the circumferential walls of the projections 30.

A chain wheel 21 is arranged on the outer jacket surface of the circumferential wall 29, by which the chain wheel can transmit torque from the crankshaft 2 to the outer rotor 22 via a chain drive not shown. have.

Each of the side covers 24 and 25 is disposed on one axial side of the axial sides of the housing 22a, respectively, and is rotatably fixed to the axial side. To this end, each projection 30 is provided with a fixing member 32, for example an axial opening through which the screw passes, which rotatably secures the side covers 24, 25 to the housing 22a.

Inside the operating devices 10a and b, a hollow space 33 is formed between each of the two protruding portions 30 neighboring in the circumferential direction. Each of the hollow spaces 33 is constrained by such limiting wall portions 34, which are opposite each other and extend substantially radially as limiting wall portions 34 of neighboring protrusions 30 in the circumferential direction, It is constrained by the side covers 24, 25 in the axial direction, by the hub member 26 facing inward in the radial direction, and by the circumferential wall 29 facing outward in the radial direction. A vane 27 protrudes into each of the hollow spaces 33, and this vane 27 is formed in such a manner that the vanes come into contact with the circumferential wall 29 as well as the side covers 24 and 25. . Each vane 27 thus divides the corresponding hollow space 33 into two interacting pressure chambers 35, 36.

The inner rotor 23 can be rotated relative to the outer rotor 22 in a defined angle range. The angular range is limited by the vane 27 in contact with the corresponding limiting wall portion 34 (advance stop 34a) of the hollow spaces 33 in one direction of rotation of the inner rotor 23. Similarly the angular range is limited in the other direction of rotation by the vane 27 being in contact with the other limiting wall portions 34 of the hollow spaces 33 serving as the crust stop 34b.

By supplying pressure to the pressure chambers 35 and 36 of one group and depressurizing the pressure chambers of the other group, the phase position of the outer rotor 22 relative to the inner rotor 23 can be varied. When pressure is supplied to both groups of pressure chambers 35 and 36, the phase positions of the two rotors 22 and 23 can be kept constant with each other. According to an alternative embodiment to this, the pressure medium may not be supplied to any of the pressure chambers 35, 36 during the phase phase constant phase. As a hydraulic pressure medium, the lubricating oil of the internal combustion engine 1 is used normally.

The pressure medium supply device 37 shown in FIG. 3 is provided for supplying pressure medium to the pressure chambers 35 and 36 or for discharging pressure medium from the pressure chambers. The pressure medium supply device 37 comprises a pressure source embodied 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 includes a supply port P, a tank port T and two operation ports A and B. Each of the pressure medium lines 41 connects the supply port P and the pressure medium pump 38, connects the first pressure chamber 35 and the first operating port A, and the second pressure chamber 36. ) And the second operation port (B), and connects the tank 39 and the tank port (T). The pressure medium is thereby able to reach the supply port P of the control valve 40 from the pressure medium pump 38 via the pressure medium line 41. In the first position of the control valve 40, the supply port P is connected to the first pressure chamber 35, while the second pressure chamber 36 is connected to the tank 39. In the second position of the control valve 40 neither of the pressure chambers 35, 36 is connected to the tank 39 and the supply port P. In the third position of the control valve 40 the supply port P is connected to the second pressure chamber 36, while the first pressure chamber 35 is connected to the tank 39.

On the camshafts 6, 7 during the operation of the internal combustion engine 1, alternating torques caused by the rolling contact of the cams 8 to the cam followers are applied. The force of the valve spring then acts on the camshafts 6, 7 in a manner that is braked until the gas exchange valve is fully open. Following this, the camshafts 6 and 7 are accelerated by the force of the valve spring. The result is a pressure peak inside the actuators 10a, b which causes the pressure chambers 35, 36 connected to the supply port P to be emptied with respect to the pressure medium pump 38. This greatly reduces the speed of adjustment. To prevent this, a check valve 42a is provided in the pressure medium line 41 connecting the control valve 40 and the pressure medium pump 38. The check valve 42a prevents backflow of the pressure medium, which may be made to the pressure medium pump 38 through the control valve 40 from the pressure chambers 35, 36. The pressure peak is reserved at the check valve 42a, whereby undesirably emptying the pressure chambers 35 and 36 is effectively prevented, thereby increasing the stability and speed of adjustment of torque transmission.

The speed of adjustment of the actuating devices 10a, b depends on the pressure medium volume flow provided by the pressure medium pump 38 or the pressure provided by the pump. The pressure provided or the pressure medium volume flow provided is itself dependent on a number of factors, such as the speed of the internal combustion engine 1 and the pressure medium temperature. The pressure medium pump 38 must be configured accordingly in order to ensure the required speed of regulation even in the worst conditions such as high pressure medium temperatures and / or low rotational speeds. Thereby a pressure medium pump 38 is used, which is configured to meet the maximum requirements of the actuating devices 10a, b, and thus is set to an oversize during most of the operating stages of the internal combustion engine 1. In addition, according to an alternative embodiment, an adjustable pressure medium pump 38 may also be used which provides the pressure medium as required. The increased complexity in these two cases negatively affects the fuel consumption and cost of the internal combustion engine 1.

In order to avoid this disadvantage, the device 10 is provided with a pressure accumulator 43. The pressure accumulator 43 includes a displaceable member that is formed as a pressure piston 45, which can be displaced against the force of the energy accumulator inside the pressure tank 44. In the illustrated embodiment the energy accumulator is implemented as a spring member 46. However, other types of energy accumulators are also conceivable, such as, for example, suitably formed elastomeric bodies or gas filled gas pockets.

The pressure piston 45 includes two pressure surfaces 47, 48. The first pressure surface 47 confines the storage space 49 together with the pressure tank 44, in which case the first pressure surface 47 confines the storage space 49 in the displacement direction of the pressure piston 45. do. The pressure tank 44 and the pressure piston 45 restrict the control space 50, in which case the second pressure surface 48 likewise limits the control space 50 in the displacement direction of the pressure piston 45. In this case the pressure piston 45 and the pressure tank 44 are formed such that no connection is made between the two pressure spaces 49, 50 in the pressure accumulator 43. In the case of the above embodiment, in order to prevent leakage, no pressure medium exchange is performed between the pressure spaces 49 and 50. In the illustrated embodiment, the pressure surfaces 47, 48 are offset from one another in the displacement direction of the pressure piston 45, in which case the first pressure surface 47 passes through the displacement direction of the pressure piston 45 vertically. It is surrounded by a second pressure surface 48 in the plane. The first pressure surface 47 is formed in a circular shape, and the second pressure surface 48 is formed in an annular shape. Since the pressure piston 45 is displaced against the force of the spring member 46 by supplying the pressure medium to the pressure spaces 49 and 50, the volume of the pressure spaces 49 and 50 increases. The path through which the pressure piston 45 can be displaced against the spring member 46 is limited by a stop 54 formed in the pressure tank 44. The stop 54 is arranged such that the storage space 49 is not connected to the control space 50.

The spring member 46 is supported on the one side of the pressure piston 45 opposite the pressure spaces 49 and 50, and on the other hand is supported on the side of the pressure tank 44 opposite the pressure spaces 49 and 50. In this case, the spring member 46 is prestressed and assembled in the pressure accumulator 43, so that the volume of the pressure spaces 49 and 50 is minimal when the system pressure is low. In this embodiment the side of the pressure piston 45 opposite the spring member 46 abuts the pressure tank 44.

The region of the pressure tank 44 opposite the pressure surfaces 47, 48 is formed as a pressure space (back pressure space 58). In this case, the surface of the pressure piston 45 toward the back pressure space 58 acts as the back pressure surface 59. By supplying a pressure medium to the back pressure space 58, a force parallel to the force of the spring member 46 acts on the pressure piston 45 via the back pressure surface 59. In the illustrated embodiment the back pressure surface 59 is formed flat and oriented perpendicular to the direction of movement of the pressure piston 45. The fact that the surface or the back pressure surface 59 includes additional functional members can likewise be considered as the surface is not flat. Thus, for example, a holding portion for the spring member 46 may be formed on the back pressure surface 59.

The storage space 49 is connected to the pressure medium supply device 37 by a storage line 51. The storage line 51, on the one hand, flows into the pressure medium supply device 37 at the rear of the check valve 42a in the flow direction and on the other hand, into the storage space 49 by the port 56. The storage line is arranged with a check valve 42c which allows the pressure medium flow from the storage space 49 to the pressure medium supply device 37 and prevents the opposite pressure medium flow. Therefore, the pressure peak generated in the operating devices 10a and b does not reach the storage space 49 of the pressure accumulator 43 and is reserved on the check valve 42c. This increases the hydraulic stiffness of the device 10.

Optionally, control space 50 may be connected to tank 39 or to a pressure source by control line 52. In the illustrated embodiment, the pressure medium pump 38 of the pressure medium supply device 37 is used as the pressure source. However, the use of other pressure sources may likewise be considered, such as the pressure medium pump 38 of a servo consumer device such as a power steering system. In this case the pressure medium discharged from the control space 50 is not guided 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. The control line 52 is provided with an additional check valve 42b which prevents the backflow of the pressure medium from the control space 50 to the pressure medium supply device 37.

Control means in the form of a directional control valve 53 for controlling the pressure medium flow directed toward or out of the control space 50 and the pressure medium flow directed toward or from the back pressure space 58. 60 is provided. The directional control valve 53 is formed as a 4/2 directional control valve and includes a pressure port P ₁ , two operation ports A ₁ and B ₁ , and a tank port T ₁ . The pressure port P ₁ is connected to a pressure source and in the illustrated embodiment is connected to the pressure medium supply device 37 via a control line 52. The third operating port A ₁ is connected to the control space 50, the fourth operating port B ₁ is connected to the back pressure space 58, and the tank port T ₁ is connected to the tank 39. . In the first control position of the directional control valve 53, the third actuation port A ₁ is connected to the pressure port P ₁ , while the fourth actuation port B _{1 is} connected to the tank port T ₁ . do. In the second control position of the directional control valve 53, the third actuation port A ₁ is connected to the tank port T ₁ , while the pressure port P _{1 is} connected to the fourth actuation port B ₁ . do.

The control line flows into the control space 50 through the second port 56 behind the directional control valve 53. In addition, a connection line 55 is provided which connects the control line 52 to the storage line 51. The connecting line 55 is introduced into the storage line 51 between the check valve 42c and the first port 56 of the storage space 49 on the one hand, and the directional control valve 53 and the control space on the other hand. Flows into the control line 52 between the second ports 56 of 50. The connection line 55 is arranged with an additional check valve 42d which allows the pressure medium flow from the control line 52 to the storage line 51 and prevents the opposite pressure medium flow.

If the adjustment request from the engine control unit is not transmitted to the device 10 during operation of the internal combustion engine 1, the control valve 40 is in the second (middle) position and the directional control valve 53 is in the first position. have. Thus no pressure medium flows into or out of the actuating device 10a. The pressure medium flow flowing from the pressure medium supply device 37 via the storage line 51 to the storage space 49 is prevented by the check valve 42d. The pressure medium is supplied to the control space 50 by the control line 52 and the direction control valve 53. At the same time, the pressure medium reaches the storage space 49 by the control line 52, the connection line 55, and the storage line 51. At the same time, the back pressure space 58 is connected to the tank 39 by the direction control valve 53. The pressure piston 45 stops against the force of the spring member 46 by acting on the first or second pressure surface 47, 48 the pressure medium introduced into the storage space 49 or the control space 50. Since it is displaced in the direction of the portion 54, the volume of the storage space 49 as well as the control space 50 increases. At the same time, the back pressure space 58 is exhausted into the tank 39. If phase angle adjustment is required from the engine control unit, the control valve 40 is switched to the first or third position of the control valve. The pressure medium thus reaches the first or second pressure chambers 35, 36 from the pressure medium pump 38, so that the phase is adjusted by the operating devices 10a, b. If the volume flow discharged from the pressure medium pump 38 must reach an adjustment speed that is too small or higher to ensure adjustment, the directional control valve 53 is switched to its second control position. In this control position the control space 50 is connected to the tank 39. This causes the pressure medium under pressure in the control space 50 to be connected to atmospheric pressure, so that the control space 50 is emptied quickly. At the same time the storage space 49 is emptied into the pressure medium supply device 37. Since the pressure medium in the control space 50 is emptied quickly so that the pressure piston 45 is supported by the first pressure surface 47 only with respect to the storage space 49, the total force of the spring member 46 is stored in the storage space. (49) acts only on. Therefore, the following equation applies to the pressure p in the storage space 49 at the beginning of the emptying process, plus the pressure formed by the filling of the back pressure chamber 58.

This is the case when the pressure piston 45 is not yet fully deflected, ie not in contact with the stop 54. In this case p _sys corresponds to the system pressure of the pressure medium supply device 37 which was provided at the start of the emptying of the pressure accumulator 43. In the pressure medium line 41, since the check valve 42a is arranged in front of the storage line 51 in the flow direction, the total pressure p and the total volume of the storage space 49 are operated by the apparatus 10a. Is not discharged into the oil passage of the internal combustion engine (1). Thus not only the current system pressure is provided, as in the case of use with a conventional pressure accumulator, but also a pressure raised by a factor of 1 + A ₂ / A ₁ .

In addition, the pressure medium is guided from the control line 52 to the back pressure space 58. The pressure medium supplies a force acting in the same direction as that of the spring member 46 to the back pressure surface 59 of the pressure piston 45. Therefore, the pressure in the storage space 49 further rises.

The pressure medium supply device 37 is thus subjected to pressure support by setting the first directional control valve 53 to the second control position, which pressure support is provided by a conventional pressure accumulator. Thus, if the size setting is the same, the adjusting speed of the actuating device 10a is significantly increased, or if the adjusting speed is the same, the actuating device 10a can be implemented smaller, which is a pressure medium pump 38 that is set or regulated to an oversize. Without taking the disadvantages of

Embodiments in which the connection line 55 is omitted and the check valve 42c does not have to be arranged in the storage line 51 are similarly considered. In the operating stage of the internal combustion engine 1 in which the phase position is kept constant, the pressure accumulator 43 is filled by the storage space 51 and the control line 52. If the system pressure drops, no pressure medium is discharged from the control space 50. As a result, the volume of the control space 50 and the storage space 49 remains constant despite the pressure drop in the pressure medium supply device 37. In this case, the following equation applies to the path x in which the pressure piston 45 is deflected from its starting position.

In the above formula A ₁ corresponds to the area of the first pressure surface 47, A ₂ corresponds to the area of the second pressure surface 48, p _max corresponds to the maximum system pressure occurring during the filling step, D corresponds to the spring constant of the spring member 46. The maximum displacement path is then limited by the stops 54. When the directional control valve 53 is switched to the second control position, it is formed by the filling of the back pressure space 58 for the pressure p provided from the pressure accumulator 43 when the pressure piston 45 is not yet fully deflected. The following equation, which is added to the pressure, applies:

In order to realize the pressure rise, the following equation should be applied to the ratio Q _D / Q _V of the pressure medium flow discharged from the control space 50 to the pressure medium flow discharged from the storage space 49.

To achieve this, the following equation applies for the minimum perfusion cross section A _D between the control space 50 and the tank 39.

In the above equation, A _V corresponds to the minimum perfusion cross section between the storage space 49 and the actuating device 10a or between the actuating device 10a and the tank 39.

Likewise, in addition to the first actuating device 10a, one or more further actuating devices 10b, 10c may be controlled by the pressure medium supply device 37 via the additional pressure medium lines 41 and the additional control valves 40. You can also think about it. The further actuating device 10b can likewise be supported by the pressure accumulator 43. For this purpose a branch to the actuating device 10b is located behind the check valve 42a in the flow direction. If the pressure accumulator 43 must support only the first actuating device 10a, the branch directed to the further actuating device 10c must be arranged in front of the check valve 42a in the flow direction.

It is likewise conceivable that the check valve 42a is arranged at the rear of the branch towards the storage line 51 in the flow direction. In this case a pressure peak is reserved between the actuating devices 10a and b and the branch to the storage line 51. As a result, the pressure peak does not reach the pressure accumulator 43, whereby a more stable torque transmission through the actuators 10a, b is achieved. It is likewise conceivable to insert one check valve 42a into the pressure medium line 41, respectively, in front of and behind the branch towards the storage line 51 in the flow direction. In this case, not only stable torque transmission is achieved through the operating devices 10a and b, but also the pressure medium volume or pressure in the storage space 49 is prevented from being discharged to the oil passage of the internal combustion engine 1.

In a slightly modified variant of the above embodiment, the check valve 42b and / or the entire pressure medium line 41 in which the check valve 42a is arranged may be omitted between the inlet points of the pressure accumulator 43. .

4 shows another embodiment of an apparatus 10 according to the invention. In this embodiment the pressure piston 45 of the pressure accumulator 43 separates the pressure tank 44 into the storage space 49 and the back pressure space 58, in which case the control space 50 is not provided. The storage space 49 is limited by the first pressure surface 47 in the displacement direction of the pressure piston 45, and the back pressure space 58 is limited by the back pressure surface 59. The storage space 49 may receive the pressure medium provided from the pressure medium supply device 37 through the storage line 51. The back pressure space 58 may be connected to the pressure source by the control line 52. In the illustrated embodiment, the control line is introduced into the pressure medium supply device 37. The control line 52 is thereby connected to the pressure medium pump 38 of the internal combustion engine 1. Alternatively, other pressure sources may be used, such as the pressure medium pump of the servo consuming device. The control line 51 is provided with a directional control valve 53 formed as a 3/2 switching valve. The direction control valve 53 includes a pressure port P ₁ , an operation port B ₁ , and a tank port T ₁ . The pressure port P ₁ is connected to the pressure medium pump 38, the operating port B ₁ is connected to the back pressure chamber 58, and the tank port T ₁ is connected to the tank 39. In the first control position of the directional control valve 53 the actuation port B ₁ is connected to the tank port T ₁ , while the pressure port P ₁ is any of the other ports B ₁ , T ₁ . It is not connected to either. When the directional control valve 53 is in the control position, the back pressure space 58 is connected to the tank 39. In the second control position of the directional control valve 53 the operating port B ₁ is connected to the pressure port P ₁ , while the tank port T ₁ is any of the other ports B ₁ , P ₁ . It is not connected to either. When the directional control valve 53 is in the control position, the back pressure space 58 receives the pressure medium from the pressure medium pump 38. The direction control valve 53 is in the first control position during the filling phase of the pressure accumulator 43. The pressure medium is provided in the storage space 49. As a result, the pressure piston 45 is displaced against the force of the spring member 46. The volume of the storage space 49 is enlarged as the volume of the back pressure space 58 is reduced. The direction control valve is in the second control position in the pressure support step. In this position a pressure medium is provided in the back pressure space 58, which pressure medium acts on the back pressure surface 59. The pressure created therefrom increases the force exerted on the pressure piston 45 from the spring member 46. This raises the support pressure provided from the storage space 49 of the pressure accumulator 43. Embodiments in which the area of the back pressure surface 59 exceeds the area of the first pressure surface 47 may also be considered. This leads to a pressure ratio which acts positively on the pressure value which can be provided.

In figure 5 another embodiment of a device according to the invention is shown. Substantially this embodiment corresponds to the embodiment shown in FIG. Unlike the embodiment of FIG. 4, one check valve 42b, c is disposed in the storage line 51 and the control line 52, respectively. The directional control valve is also formed as a 4/2 directional control valve, in which case an additional actuation port A ₁ is connected to the storage space 49. In the first control position of the directional control valve 53, an additional actuation port A ₁ is connected to the pressure port P ₁ . In the second control position of the directional control valve 53 the actuation port A ₁ is not connected to any of the other ports B ₁ , P ₁ , T ₁ . In this embodiment the pressure medium reaches from the pressure medium pump 38 via the control line 52 and the direction control valve 53 into the storage space 49 as long as the direction control valve is in the first control position. At the same time, the back pressure space 58 is exhausted into the tank 39. When the directional control valve 53 is in the second control position, the operating port A ₁ is closed and the back pressure space 58 is supplied with the pressure medium from the pressure medium pump 38. At the same time the storage space 49 is emptied into the pressure medium supply device 37. The check valve 42c lubricates the pressure accumulator 43 against pressure peaks occurring in the operating devices 10a and b.

In all illustrated embodiments, the pressure accumulator 43 is introduced into the pressure medium line 41 connecting the control valve (s) 40 and the pressure medium pump 38. Similarly, an embodiment is conceivable in which the pressure accumulator (s) 43 are introduced into a pressure medium line 41 connecting the actuating devices 10a, b and the control valve (s) 40.

In addition to using the pressure accumulator 43 in applications for variable control of the control time in the internal combustion engine 1, this pressure accumulator 43 is used in another vehicle field, for example in a switchable cam follower, or in an automated manner. It may also be used in the field of transmissions.

1: internal combustion engine
2: crankshaft
3: piston
4: cylinder
5: traction drive
6: intake camshaft
7: exhaust camshaft
8: Cam
9a: intake gas exchange valve
9b: exhaust gas exchange valve
10: device
10a: first operating device
10b: additional actuating device
21: chain wheel
22: external rotor
22a: housing
23: inner rotor
24: side cover
25: side cover
26: hub member
27: vane
27a: vane spring
28: vane groove
29: circumferential wall
30: protrusion
32: fixed member
33: hollow space
34: limited wall
34a: advance stop
34b: crust 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
43: pressure accumulator
44: pressure tank
45: pressure piston
46: spring member
47: first pressure surface
48: second pressure surface
49: storage space
50: control space
51: storage line
52: control line
53: directional control valve
54: stop
55: connection line
56: port
58: back pressure space
59: back pressure surface
60 control means
A: first operating port
B: second operating port
P: supply port
T: discharge port
A ₁ : third operating port
B ₁ : fourth operating port
P ₁ Pressure port
T ₁ Tank port

Claims (10)

It is an apparatus 10 for variably adjusting the control time of the gas exchange valves 9a and b of the internal combustion engine 1,
A drive member 22, an output member 23, one or more pressure chambers 35, 36, a pressure medium supply device 37, and one or more pressure accumulators 43,
The pressure medium supply device 37 can supply or discharge pressure medium to or from one or more pressure chambers 35 and 36,
The phase position of the output member 23 relative to the drive member 22 can be varied by supplying pressure medium to the pressure chambers 35 and 36 or withdrawing pressure medium from the pressure chamber,
The pressure accumulator 43 comprises a displaceable member 45 having a first pressure surface 47 which partially restricts the storage space 49,
The storage space 49 may or may be connected to the pressure medium supply device 37,
The energy accumulator supplies a force to the displaceable member 45 in the direction of the starting position,
In the device for variably adjusting the control time of the gas exchange valve of the internal combustion engine, the displaceable member 45 can be displaced against the force of the energy accumulator 46 by applying pressure to the storage space 49. ,
The displaceable member 45 includes a back pressure surface 59 at least partially restricting the back pressure space 58, and the displaceable member 45 is supplied in the direction of the starting position by supplying a pressure medium to the back pressure space 58. Apparatus (10) for varying the control time of a gas exchange valve of an internal combustion engine, characterized in that it can be displaced. 2. The displaceable member 45 comprises at least one second pressure surface 48 which partially constrains the control space 50, wherein the displaceable member 45 is displaceable by supplying pressure to the control space 50. Internal combustion, characterized in that 45 may be displaced against the force of the pressure accumulator 46 and the pressure medium flow from the storage space 49 to the control space 50 in the pressure accumulator 43 is inhibited. Apparatus 10 for variably adjusting the control time of the gas exchange valve of the engine. The internal combustion engine according to claim 2, wherein the displaceable member (45) is displaced in the same direction as when the pressure medium is supplied to the control space (50) by supplying the pressure medium to the storage space (49). Apparatus for variably adjusting the control time of the gas exchange valve of the apparatus 10. Apparatus for variably adjusting the control time of a gas exchange valve of an internal combustion engine, according to claim 1, characterized in that the back pressure space 58 can be selectively connected to the pressure source 38 or to the tank 39. 10). A control means (60) is provided, in which case the back pressure space (58) can be selectively connected to the tank (39) or to the pressure source (38) by the control means (60). Apparatus (10) for varying the control time of a gas exchange valve of an internal combustion engine, characterized in that there is. The device (10) according to claim 1, characterized in that the back pressure space can be connected to a pressure medium pump (38) of the internal combustion engine (1). The device (10) according to claim 1, characterized in that the back pressure space can be connected to the tank (39) of the internal combustion engine (1). 6. The directional control valve 56 according to claim 5, comprising a pressure source 38, a tank 39, and one port G, B, T connected to the back pressure space 58, respectively. Device (10) for variable adjustment of the control time of the gas exchange valve of the internal combustion engine. 9. The control time of the gas exchange valve of the internal combustion engine according to claim 8, characterized in that the directional control valve (56) comprises an additional port (A) connected to the storage space (49) or the control space (50). Device 10 for variable adjustment. An apparatus for variably adjusting the control time of a gas exchange valve of an internal combustion engine according to claim 2, characterized in that the storage space 49 and the control space 50 are not connected to each other in the pressure accumulator 43. 10).

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