EP2215332B1 - 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

Field of the invention

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

Background of the invention

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

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

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

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

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

A disadvantage of this embodiment is the fact that the pressure accumulator is emptied even if the system pressure is not due to an adjustment, but due to other external circumstances, for example, by a decrease in speed drops. Thus, for a subsequent Phasenverstellvorgang lower pressure support and a lower pressure medium volume from the pressure accumulator available.

A further disadvantage is that the maximum pressure with which the pressure accumulator can support the pressure medium supply device corresponds to the pressure which prevailed in the pressure medium supply device immediately before the phase adjustment process. Will at high temperatures and low speeds from the engine control an adjustment request addressed to the device, the pressure support of the accumulator falls lower, since the system pressure at which the pressure accumulator was filled, was low. This can result in that the adjustment process can not be carried out, or the adjustment speed is significantly reduced. Thus, an interpretation of the pressure medium pump on the peak load with the resulting disadvantages is also required in this case.

Object of the invention

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

The object is achieved in that the displaceable element has a counter-pressure surface which limits a counter-pressure space at least partially, which can be displaced by pressure medium loading of the counter-pressure space, the displaceable element in the direction of the starting position.

The displaceable element may be formed, for example, as a pressure piston, which can be moved within a pressure vessel against the force of an example designed as a spring element force accumulator. When pressure medium supply to the reservoir increases its volume at the expense of the back pressure chamber. If the system pressure in the pressure medium supply device falls, then the force of the energy accumulator exceeds the force caused by the system pressure on the first pressure surface. Thus, the pressure piston is urged by the energy storage in an initial position in which the volume of the storage space is minimal.

As an alternative to the spring element, other forms of energy storage can be used, for example, reversibly deformable body, such as elastomers, or gas-filled bubbles.

If the counterpressure space is subjected to pressure medium in the operating phases of the internal combustion engine, in which the pressure accumulator is to deliver pressure medium to the pressure medium supply device, a further force acting on the displaceable element acts in addition to the force of the energy accumulator, urging it in the direction of the starting position. This additional force results from the pressure in the back pressure chamber, which acts on the counter pressure surface. For their amount F: F = pA _G , where p corresponds to the pressure acting on the counter-pressure surface and A _G corresponds to the surface area of the counter-pressure surface.

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

In a further development of the invention can be provided that the displaceable element has at least a second pressure surface, which limits a control room partially, wherein the displaceable element can be moved against the force of the energy storage by pressurizing the control chamber and wherein within the pressure accumulator a pressure medium flow of the Reservoir is prevented in the control room. In addition, it can be provided that the reservoir and the control chamber do not communicate with each other within the pressure accumulator. Advantageously, a pressurizing of the storage space displaces the displaceable element in the same direction as a pressurizing of the control chamber, advantageously of the advantageously away from the starting position of the displaceable element.

Due to the design of the pressure accumulator with a displaceable element, which partially isolated pressure chambers within the pressure accumulator, these two pressure chambers can be controlled separately, i. filled and / or emptied. Apart from leakage, there is no connection between the pressure chambers. For example, different pressure sources for filling the storage space and the control room can be used.

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

ansteigen, abhängig von der Last, die in diesem Zeitpunkt auf den Kraftspeicher wirkt. Dabei entspricht A₁ dem Flächeninhalt der ersten Druckfläche und A₂ dem Flächeninhalt der zweiten Druckfläche. Wird als Kraftspeicher beispielsweise ein Federelement eingesetzt, so steigt der Druck bei Beginn des Unterstützungsvorgangs um den vollen Faktor $\frac{A_1+A_2}{A_1}$

an, solange die Feder noch nicht ihren maximal komprimierten Zustand erreicht hat.If it is provided that a pressurization of the storage space displaces the displaceable element in the same direction as a pressurizing of the control space, the control space can support the filling of the storage space. For this purpose, the control chamber is also filled with pressure medium during the filling process of the storage space. As a result, a force acts on both pressure surfaces of the pressure piston, whereby a higher force is stored in the energy store (the spring element is compressed more strongly). Receives the filled pressure accumulator from the engine control command to support the Phasenverstellvorgang, so the control room can be emptied independently of the storage room. That is, while the storage space is emptied into the pressure medium supply device, and thus supports the Phasenverstellvorgang, the control chamber can be vented against atmospheric pressure in a tank. By suitable design, the venting of the control chamber can be done faster than the emptying of the reservoir into the pressure medium supply device. Thus, the entire force that was stored in the energy storage acts on the first pressure surface on the pantry. As a result, the pressure at the beginning of the assist process can be reduced by up to a factor of $$\frac{A_1+A_2}{{\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">A</figure-callout>}}_1}$$

increase, depending on the load that acts on the energy storage at this time. Here A ₁ corresponds to the surface area of the first pressure surface and A ₂ corresponds to the surface area of the second pressure surface. If, for example, a spring element is used as the force store, the pressure at the start of the assistance process increases by the full factor $\frac{A_{}}{}$$\frac{{}_1+A_2}{{\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">A</figure-callout>}}_1}$

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

In a further development of the invention, the counterpressure space can optionally be connected to a pressure source or a tank.

It can be provided control means, wherein the counter-pressure space can be selectively connected by means of the control means with a tank or a pressure source.

In this case, the counterpressure space can be connected to the pressure medium pump of the internal combustion engine. The counter-pressure space can be connected to the tank of the internal combustion engine.

The pressure source can be, for example, the pressure medium supply device or its pressure medium pump or a separate source, for example the pressure source of a servo consumer (eg the power steering). In the second case, the pressure accumulator can be completely filled even in operating phases with low system pressure. The optional connection to a pressure source or the tank is via control means, for example a 3/2-way valve in the form of a switching valve (for example seat valve) or a proportional valve (for example slide valve). Alternatively, two control means come into consideration, one of the control means blocks the connection pressure source -> back pressure chamber and the other control means the connection back pressure chamber -> tank or releases. The control means may be, for example, electromagnetically actuated hydraulic valves, such as directional control valves (for example switching or proportional valves), pilot operated check valves or the like. These control means receive from an engine control unit of the internal combustion engine control signals, according to which the counter-pressure chamber is filled or emptied, that is, whether the pressure accumulator to be filled or the emptying process to be supported.

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

If the tank and / or the pressure medium pump of the internal combustion engine used for filling or venting the back pressure chamber, so no other components are needed than already present in the internal combustion engine. Furthermore, the requirements for the seal between the pressure medium container and the pressure piston are lower, since a mixing of the pressure medium in the reservoir and the back pressure chamber is permitted. Thus, it is possible to dispense with a sealing element which acts between the pressure piston and the pressure vessel.

Furthermore, it can be provided that a directional control valve is provided as the control means, each having a connection which is connected to the pressure source, the tank, and the counter-pressure space. In a development of the invention, a further connection can be provided, which is connected to the storage space or the control space.

The pressure support of the pressure accumulator can thus be activated by simply switching one or more control means. In this case, the pressure medium volume is provided which is collected in the operating phase of the internal combustion engine in which the phase position is kept constant in the storage space.

The pressure support of the accumulator can be used with each Phasenverstellvorgang. For this purpose, the control means (directional valves and / or unlockable check valves) are always brought into the position in which the storage space is emptied when a phase adjustment is requested. In the operating phases between the Phasenverstellanforderungen the accumulator can fill.

Another possibility is to switch on the pressure support of the pressure accumulator as needed. If the engine control detects that the pressure or volume flow delivered by the pressure medium pump is insufficient for phase adjustment, it releases the pressure support through the pressure accumulator. This procedure extends the times in which the accumulator can be filled and thus the performance of the pressure accumulator during pressure support.

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

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

Advantageously, the maximum volume of the storage space corresponds to at least twice the volume required for a phase adjustment from a maximum late position to a maximum advance position.

The pressure accumulator can open, for example, in the pressure medium line between the pressure medium pump and the control valve.

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

Brief description of the drawings

Figur 1

nur sehr schematisch eine Brennkraftmaschine,

Figur 2a

einen Längsschnitt durch die Stelleinrichtung

Figur 2b

einen Querschnitt durch eine Stelleinrichtung,

Figur 3

eine erste erfindungsgemäße Ausführungsform einer Vorrichtung,

Figur 4

eine zweite erfindungsgemäße Ausführungsform einer Vorrich- tung,

Figur 5

eine dritte erfindungsgemäße Ausführungsform einer Vorrichtung.

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. 2a

a longitudinal section through the actuator

FIG. 2b

a cross section through an adjusting device,

FIG. 3

a first embodiment of a device according to the invention,

FIG. 4

A second embodiment of a device according to the invention,

FIG. 5

a third embodiment of a device according to the invention.

Detailed description of the drawings

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, each with a traction drive 5 with an intake camshaft 6 and exhaust camshaft 7 in conjunction, wherein a first and a second device 10 for a relative rotation between the crankshaft 2 and the camshafts 6, 7 provide. The devices 10 each comprise a hydraulic actuator 10a, b and a pressure medium supply device 37. Cams 8 of the camshafts 6, 7 actuate one or more inlet gas exchange valves 9a or one or more exhaust gas exchange valves 9b. Likewise, it may be provided to equip only one of the camshafts 6, 7 with a device 10, or to provide only one camshaft 6, 7, which is provided with a device 10.

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

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

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

On an outer circumferential surface of the peripheral wall 29, a sprocket 21 is arranged, by means of which, via a chain drive, not shown, torque can be transmitted from the crankshaft 2 to the outer rotor 22.

Depending on one of the side covers 24, 25 is arranged on one of the axial side surfaces of the housing 22a and rotatably fixed thereto. For this purpose, an axial opening is provided in each projection 30, which is penetrated by a fastening element 32, for example a screw, which serves for the rotationally fixed fixing of the side covers 24, 25 on the housing 22a.

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

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

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

For supplying pressure medium to or removing pressure medium from the pressure chambers 35, 36, a pressure medium supply device 37 is provided, which in FIG. 3 is shown. The pressure medium supply device 37 comprises a pressure source, which is designed as a pressure medium pump 38, a tank 39, a control valve 40 and a plurality of pressure medium lines 41. The control valve 40 has an inlet port P, a tank port T and two working ports A, B on. In each case, one of the pressure medium line 41 connects the pressure medium pump 38 with the inlet port P, the first working port A with the first pressure chamber 35, the second working port B with the second pressure chamber 36 and the tank port T to the tank 39. Thus, pressure medium from the pressure medium pump 38 via the pressure medium line 41 to the inlet port P of the control valve 40 pass.

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

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

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

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

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

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

The pressure piston 45 has two pressure surfaces 47, 48. Together with the pressure vessel 44, the first pressure surface 47 delimits a reservoir 49, the first pressure surface 47 delimiting the reservoir 49 in the direction of displacement of the pressure piston 45. The pressure vessel 44 and the pressure piston 45 define a control chamber 50, the second pressure surface 48 also delimits the control chamber 50 in the direction of displacement of the pressure piston 45. In this case, the pressure piston 45 and the pressure vessel 44 are formed such that within the pressure accumulator 43, there is no connection between the two pressure chambers 49 and 50. Apart from leakage, no pressure medium exchange between these pressure chambers 49, 50 takes place in this embodiment. In the illustrated embodiment, the pressure surfaces 47, 48 are arranged offset to one another in the displacement direction of the pressure piston 45, wherein the first pressure surface 47 in the plane which is pierced perpendicularly by the displacement direction of the pressure piston 45, surrounded by the second pressure surface 48. The first pressure surface 47 is circular and the second pressure surface 48 is annular. By pressurizing the pressure chambers 49, 50, the pressure piston 45 is displaced against the force of the spring element 46, whereby the volume of the pressure chambers 49, 50 increases. The way that the pressure piston 45 can be displaced against the spring element 46 is limited by stops 54 which are formed within the pressure vessel 44. The stops 54 are arranged such that a connection of the storage space 49 is prevented with the control chamber 50.

The spring element 46 is supported, on the one hand, on the side of the pressure piston 45 facing away from the pressure chambers 49, 50 and, on the other hand, on the side of the pressure vessel 44 facing away from the pressure chambers 49, 50. In this case, the spring element 46 is mounted with bias in the pressure accumulator 43, so that the volume of the pressure chambers 49, 50 is minimal at low system pressure. In this initial position of the pressure piston 45 is located on the spring element 46 facing away from the pressure vessel 44 at.

The area of the pressure vessel 44 facing away from the pressure surfaces 47, 48 is designed as a pressure space (counterpressure space 58). In this case, the surface of the pressure piston 45 facing the counter-pressure chamber 58 acts as a counterpressure surface 59. By applying pressure medium to the counterpressure space 58, a force acts on the pressure piston 45 via the counterpressure surface 59, which force is directed parallel to the force of the spring element 46. In the illustrated embodiment, the counter-pressure surface 59 is formed flat, which is oriented perpendicular to the direction of movement of the pressure piston 45. Also conceivable are salaried areas or that the counter-pressure surface 59 has further functional elements, so that it deviates from the planar shape. For example, holders for the spring element 46 could be formed on the counter-pressure surface 59.

The storage space 49 is connected by means of a supply line 51 to the pressure medium supply device 37. The supply line 51 opens on the one hand downstream of the check valve 42a in the pressure medium supply means 37 and on the other hand via a connection 56 in the reservoir 49. In the supply line, a check valve 42c is arranged, which allows a flow of pressure medium from the reservoir 49 to the pressure medium supply means 37 and prevents an opposite pressure medium flow , It is thereby achieved that in the adjusting devices 10a, b generated pressure peaks can not penetrate up to the reservoir 49 of the pressure accumulator 43, but are supported on the check valve 42c. Thus, the hydraulic rigidity of the device 10 is increased.

The control chamber 50 can optionally be connected to a tank 39 or by means of a control line 52 to a pressure source. In the illustrated embodiment serves as a pressure source, the pressure medium pump 38 of the pressure medium supply device 37. It is also conceivable that another source of pressure, such as the pressure medium pump 38 of a servo load, eg. The power steering, is used. In this case, that will be done by the Control chamber 50 outflowing pressure fluid is not directed into the tank 39 of the lubricating oil circuit of the internal combustion engine 1, but to the corresponding tank 39 of the servo consumer.

In the control line 52, a further check valve 42 b is provided, which prevents a backflow of pressure medium from the control chamber 50 to the pressure medium supply device 37.

In order to control the pressure medium flow to and from the control chamber 50 and the back pressure chamber 58, a control means 60 in the form of a directional control valve 53 is provided. The directional control valve 53 is designed as a 4/2-way valve and has a pressure port P ₁ , two working ports A ₁ , B ₁ and a tank port T ₁ . The pressure port P ₁ is connected to the pressure source, in the illustrated embodiment via the control line 52 to the pressure medium supply means 37. The third working port A ₁ is connected to the control chamber 50, the fourth working port B ₁ to the counter-pressure chamber 58 and the tank port T ₁ to the tank 39. In a first control position of the directional valve 53, the third working port A ₁ is connected to the pressure port P _1, while the fourth working port B ₁ communicates with the tank port T. ₁

In a second control position of the directional valve 53, the third working port A ₁ is connected to the tank port T _1, while the pressure port P ₁ communicates with the fourth working port _B1.

The control line leads to the directional control valve 53 via a second connection 56 in the control chamber 50. Furthermore, a connecting line 55 is provided which connects the control line 52 to the supply line 51. The connecting line 55 opens on the one hand between the check valve 42c and the first terminal 56 of the storage space 49 in the supply line 51 and on the other hand between the directional control valve 53 and the second port 56 of the control chamber 50 in the control line 52. In the connecting line 55, a further check valve 42d is arranged , which allows a flow of pressure medium from the control line 52 to the supply line 51 and prevents an opposing flow of pressure medium.

plus des Drucks der durch die Befüllung der Gegendruckkammer 58 erzeugt wird. Dies gilt, wenn der Druckkolben 45 noch nicht vollständig ausgelenkt wurde, also nicht an den Anschlägen 54 anliegt. Dabei entspricht p_sys dem Systemdruck der Druckmittelversorgungseinrichtung 37, welcher bei Beginn der Entleerung des Druckspeichers 43 vorlag.If no adjustment request is directed to the device 10 during operation of the internal combustion engine 1 by the engine control, the control valve 40 is in the second (middle) position and the directional control valve 53 is in the first position. Consequently, no pressure fluid flows to or from the actuator 10a. A pressure medium flow from that of the pressure medium supply device 37 via the supply line 51 to the reservoir 49 is prevented by the check valve 42d. Via the control line 52 and the directional control valve 53, the control chamber 50 is acted upon by pressure medium. At the same time pressure medium passes through the control line 52, the connecting line 55 and the supply line 51 into the reservoir 49. At the same time, the counter-pressure chamber 58 is connected via the directional control valve 53 to the tank 39. The introduced into the reservoir 49 and the control chamber 50 pressure medium acts on the first and second pressure surface 47, 48, whereby the pressure piston 45 is displaced in the direction of the stops 54 against the force of the spring element 46, so that the volume of both the control chamber 50th and the storage space 49 increases. At the same time the back pressure chamber 58 is vented into the tank 39. If a phase angle adjustment is requested by the engine control unit, the control valve 40 is transferred into its first or third position. Thus, pressure medium passes from the pressure medium pump 38 to the first and second pressure chambers 35, 36, whereby a phase adjustment by the actuator 10a, b is caused. If the volume flow delivered by the pressure medium pump 38 is too low to ensure the adjustment or if a higher adjustment speed is to be achieved, the first directional control valve 53 is transferred into its second control position. In this control position, the control chamber 50 is connected to a tank 39. The under pressure in the control chamber 50 pressure medium is thus connected to atmospheric pressure, whereby a rapid draining of the control chamber 50 takes place. At the same time, the storage space 49 is emptied into the pressure medium supply device 37. If the pressure fluid emptying of the control chamber 50 so fast that the pressure piston 45 is supported exclusively on the first pressure surface 47 relative to the reservoir 49, the entire force of the spring element 46 acts only on the reservoir 49. Thus applies to the pressure p in the reservoir 49 at the beginning of the emptying process: $$p=\frac{p_{\mathit{sys}}\left(A_1+A_2\right)}{{\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">A</figure-callout>}}_1}$$

plus the pressure generated by the filling of the back pressure chamber 58. This applies if the pressure piston 45 has not yet been completely deflected, that is, it does not bear against the stops 54. In this case, p _sys corresponds to the system pressure of the pressure medium supply device 37, which was present at the beginning of the emptying of the pressure accumulator 43.

Since the check valve 42a is arranged in the pressure medium line 41 upstream of the supply line 51, it is ensured that the total pressure p and the entire volume of the reservoir 49 of the actuator 10a is available and not drained into the oil gallery of the internal combustion engine 1. Thus, not only, as in applications with conventional accumulators, the current system pressure is available, but by a factor of 1 + A ₂ / A ₁ increased pressure.

In addition, pressure medium from the control line 52 is passed into the counter-pressure chamber 58. This acts on the counter-pressure surface 59 of the pressure piston 45 with a force which acts in the same direction as that of the spring element 46. As a result, the pressure in the reservoir 49 is additionally increased.

The pressure medium supply device 37 can thus learn by adjusting the second control position on the first directional control valve 53, a pressure support, which is above the conventional pressure accumulator. Thus, the adjustment speed of the adjusting device 10a can be increased significantly with the same dimensioning or the adjusting device 10a can be made smaller at the same adjustment speed without having to accept the disadvantages of an oversized or regulated pressure medium pump 38.

wobei A₁ dem Flächeninhalt der ersten Druckfläche 47, A₂ dem Flächeninhalt der zweiten Druckfläche 48, p_max dem während der Befüllphase maximal auftretenden Systemdruck und D der Federkonstante des Federelements 46 entspricht. Dabei ist der maximale Verschiebeweg durch die Anschläge 54 begrenzt.Likewise conceivable are embodiments in which the connecting line 55 and the arrangement of a check valve 42c in the supply line 53 are dispensed with. In operating phases of the internal combustion engine 1, in which the phase position is kept constant, the pressure accumulator 43 fills over the storage space 51 and the control line 52. If the system pressure drops, then no pressure medium flows from the control chamber 50 from. This has the consequence that the volume of the control chamber 50 and the storage space 49 remains constant despite the pressure drop in the pressure medium supply device 37. In this case, for the way x, the pressure piston 45 has been deflected from its initial position: $$x=\frac{p_{\mathrm{Max}}\left(A_1+A_2\right)}{D}.$$

wherein A ₁ corresponds to the surface area of the first pressure surface 47, A ₂ corresponds to the surface area of the second pressure surface 48, p _{max to} the system pressure occurring maximally during the filling phase, and D corresponds to the spring constant of the spring element 46. The maximum displacement is limited by the stops 54.

plus des Drucks der durch die Befüllung der Gegendruckkammer 58 erzeugt wird.If the directional control valve 53 is transferred into the second switching position, the following applies for the pressure p provided by the pressure accumulator 43, when the pressure piston 45 is not yet completely deflected: $$p=\frac{p_{\mathrm{Max}}\left(A_1+A_2\right)}{{\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">A</figure-callout>}}_1}$$

plus the pressure generated by the filling of the back pressure chamber 58.

gelten. Um dies zu erreichen ist vorgesehen, dass für den minimalen Durchflussquerschnitt zwischen dem Steuerraum 50 und dem Tank 39 A_D $$A_D>\frac{A_2}{A_1}{A}_V$$

gilt, wobei Av dem minimalen Durchflussquerschnitt zwischen dem Vorratsraum 49 und der Stelleinrichtung 10a bzw. der Stelleinrichtung 10a und dem Tank 39 entspricht.In order to realize the pressure increase must for the ratio of the pressure medium flow from the control chamber 50 to the pressure medium flow from the reservoir 49 Q _D / Q _V $$\frac{Q_D}{Q_V}>\frac{A_2}{{\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">A</figure-callout>}}_1}.$$

be valid. To achieve this, it is provided that for the minimum flow cross section between the control chamber 50 and the tank 39 A _D $$A_D>\frac{A_2}{{\mathrm{<figure-callout\; id="1"\; label="A"\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">A</figure-callout>}}_1}{A}_V$$

where Av is the minimum flow area between the reservoir 49 and the actuator 10a and the actuator 10a and the tank 39 corresponds.

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

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

It is also conceivable to arrange the check valve 42a downstream of the branch to the supply line 51. In this case, the support of the pressure peaks between the actuator 10a, b and the branch to the supply line 51. The pressure peaks thus can not reach the pressure accumulator 43, whereby a stiffer torque transmission by the actuator 10a, b is achieved.

Also conceivable is the use of a respective check valve 42a in the pressure medium line 41 upstream and downstream of the branch to the supply line 51. In this case, both a rigid torque transmission by the actuator 10a, b is achieved and prevents the pressure, or the pressure center volume of the reservoir 49th flows into the oil gallery of the internal combustion engine 1.

In a slight modification of the embodiment, the check valve 42b and / or the entire pressure medium line 41, in which the check valve 42a is arranged, between the orifice points of the pressure accumulator 43 could be omitted.

FIG. 4 shows a further embodiment of the invention an apparatus 10. The pressure piston 45 of the accumulator 43 separates in this embodiment, the pressure vessel 44 in a reservoir 49 and the back pressure chamber 58, wherein no control chamber 50 is provided. The pantry 49 is limited in the direction of displacement of the pressure piston 45 of the first pressure surface 47 and the back pressure chamber 58 of the reaction surface 59. The storage space 49 can be acted upon by the supply line 51 with pressure medium from the pressure medium supply device 37. Via the control line 52, the counter-pressure space 58 can be connected to a pressure source. In the illustrated embodiment, the control line opens into the pressure medium supply means 37. The control line 52 is thus connected to the pressure medium pump 38 of the internal combustion engine 1. Alternatively, other pressure sources, such as the pressure medium pump of a servo load can be used.

In the control line 51 designed as a 3/2-way valve control valve 53 is provided. The directional control valve 53 has a pressure port P ₁ , a working port B ₁ and a tank port T ₁ . The pressure port P ₁ is connected to the pressure medium pump 38, the working port B ₁ to the back pressure chamber 58 and the tank port T ₁ to the tank 39.

In the first control position of the directional valve 53, the working port B ₁ is connected to the tank port T _1, while the pressure port P ₁ with any of the other terminals B _1, T communicates. ₁ The directional control valve 53 is in this control position, the back pressure chamber 58 is connected to the tank 39.

In the second control position of the directional valve 53, the working port B ₁ is connected to the pressure port P _1, while the tank port T ₁ with any of the other terminals B _1, P ₁ communicates. If the directional control valve 53 is in this control position, then the counter-pressure chamber 58 is acted upon by the pressure medium pump 38 with pressure medium.

During the filling phases of the pressure accumulator 43, the directional control valve 53 is in the first control position. Pressure medium is supplied to the reservoir 49. As a result, the pressure piston 45 is displaced against the force of the spring element 46. The volume of the storage space 49 increases at the expense of the volume of the counter-pressure space 58.

In the pressure assist phases, the directional control valve is in the second control position. In this position, the counter-pressure chamber 58 pressure medium is supplied, which acts on the counter-pressure surface 59. The resulting Pressure force increases the force exerted by the spring element 46 on the pressure piston 45 force. Thus, the support pressure provided from the accumulator 43 from the reservoir 49 is increased.

Also conceivable are embodiments in which the surface area of the counterpressure surface 59 exceeds the surface area of the first pressure surface 47. As a result, a pressure boost is achieved, which has a positive effect on the deliverable pressure value.

In FIG. 5 a further embodiment of a device according to the invention is shown. This essentially corresponds to the one in FIG. 4 illustrated embodiment. In contrast to the embodiment of FIG. 4 in each case a check valve 42b, c in the supply line 51 and the control line 52 is arranged. Furthermore, the directional control valve is designed as a 4/2-way valve, wherein the additional working port A _{1 is} connected to the reservoir 49. In the first control position of the directional control valve 53, the additional working port A _{1 is} connected to the pressure port P ₁ . In the second control position of the directional control valve 53, the working port A ₁ communicates with none of the other ports B ₁ , P ₁ , T ₁ .

Pressure medium can reach in this embodiment of the pressure medium pump 38 via the control line 52 and the directional control valve 53 into the reservoir 49, as long as the directional control valve is in the first control position. At the same time the back pressure chamber 58 is vented to the tank 39.

The directional control valve 53 is in the second control position, the working port A _{1 is} closed and the counter-pressure chamber 58 is acted upon by the pressure medium pump 38 with pressure medium. At the same time, the storage space 49 empties into the pressure medium supply device 37.

The check valve 42c shields the accumulator 43 against pressure peaks, which arise in the adjusting devices 10a, b.

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

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

reference numeral

1

Internal combustion engine

2

crankshaft

3

piston

4

cylinder

5

traction drive

6

intake camshaft

7

exhaust

8th

cam

9a

Inlet gas exchange valve

9b

Auslassgaswechselventil

10

contraption

10a

first adjusting device

10b

further adjusting device

21

Sprocket

22

outer rotor

22a

casing

23

inner rotor

24

side cover

25

side cover

26

hub element

27

wing

27a

wing feathers

28

vane

29

peripheral wall

30

head Start

32

fastener

33

cavity

34

boundary wall

34a

early stop

34b

late stop

35

first pressure chamber

36

second pressure chamber

37

Pressure medium supply device

38

Hydraulic pump

39

tank

40

control valve

41

Pressure medium line

42a

check valve

42b

check valve

42c

check valve

42d

check valve

43

accumulator

44

pressure vessel

45

pressure piston

46

spring element

47

first printing surface

48

second printing surface

49

pantry

50

control room

51

supply line

52

control line

53

way valve

54

attack

55

connecting line

56

connection

58

Counterpressure chamber

59

Counterpressure surface

60

control means

A

first work connection

B

second work connection

P

inflow connection

T

drain connection

A ₁

third work connection

B ₁

fourth work connection

P ₁

pressure connection

T ₁

tank connection

Claims (10)

1. Device (10) for variably adjusting the control times of gas exchange valves (9a,b) of an internal combustion engine (1), having
   a drive input element (22), a drive output element (23), at least one pressure chamber (35, 36), a pressure medium supply device (37) and at least one pressure accumulator (43),
   with it being possible for pressure medium to be supplied to or discharged from the at least one pressure chamber (35, 36) by means of the pressure medium supply device (37),
   with it being possible for a phase position of the drive output element (23) relative to the drive input element (22) to be varied by means of the supply of pressure medium to or discharge of pressure medium out of the pressure chamber (35, 36),
   with the pressure accumulator (43) having a movable element (45) which is provided with a first pressure surface (47) which partially delimits a store chamber (49),
   with the store chamber (49) being connected or being able to be connected to the pressure medium supply device (37),
   with a force store loading the movable element (45) with a force in the direction of an initial position, and
   with it being possible by means of the pressurization of the store chamber (49) for the movable element (45) to be moved counter to the force of the force store (46), characterized in that the movable element (45) has a counterpressure surface (59) which at least partially delimits a counterpressure chamber (58), with it being possible by means of the pressurization of the counterpressure chamber (58) for the movable element (45) to be moved in the direction of the initial position.
2. Device (10) according to Claim 1, characterized in that the movable element (45) has at least one second pressure surface (48) which partially delimits a control chamber (50), with it being possible by means of the application of pressure medium to the control chamber (50) for the movable element (45) to be moved counter to the force of the force store (46), and with a pressure medium flow within the pressure accumulator (43) from the store chamber (49) into the control chamber (50) being prevented.
3. Device (10) according to Claim 2, characterized in that an application of pressure medium to the store chamber (49) moves the movable element (45) in the same direction as an application of pressure medium to the control chamber (50).
4. Device (10) according to Claim 1, characterized in that the counterpresssure chamber (58) can be selectively connected to a pressure source (38) or to a tank (39).
5. Device (10) according to either of Claims 1 and 2, characterized in that control means (60) are provided, with it being possible for the counterpressure chamber (58) to be selectively connected to a tank (39) or to a pressure source (38) by the control means (60).
6. Device (10) according to Claim 1, characterized in that the counterpressure chamber can be connected to the pressure medium pump (38) of the internal combustion engine (1).
7. Device (10) according to Claim 1, characterized in that the counterpressure chamber can be connected to the tank (39) of the internal combustion engine (1).
8. Device (10) according to Claim 5, characterized in that a directional valve (56) is provided as a control means (60), which directional valve (56) has in each case one port (G, B, T) connected to the pressure source (38), to the tank (39) and to the counterpressure chamber (58).
9. Device (10) according to Claim 8, characterized in that the directional valve (56) has a further port (A) which is connected to the store chamber (49) or to the control chamber (50).
10. Device (10) according to Claim 2, characterized in that the store chamber (49) and the control chamber (50) do not communicate with one another within the pressure accumulator (43).

Images