US20060260578A1

US20060260578A1 - Apparatus for the variable setting of the control times of gas exchange valves of an internal combustion engine

Info

Publication number: US20060260578A1
Application number: US11/419,301
Authority: US
Inventors: Olaf Boese; Gerhard Scheidig; Andreas Strauss; Rainer Ottersbach
Original assignee: Schaeffler KG
Current assignee: IHO Holding GmbH and Co KG
Priority date: 2005-05-20
Filing date: 2006-05-19
Publication date: 2006-11-23

Abstract

The invention relates to an apparatus (1) for the variable setting of the control times of gas exchange valves of an internal combustion engine, having a stator (2) and an output element (3) which is arranged coaxially with respect to the former, the two components being mounted such that they can rotate with respect to one another, and having a housing (11) which is configured separately with respect to the stator (2) and with respect to the output element (3) and which surrounds the stator (2) and the output element (3) at least partly and prevents engine oil escaping from the apparatus (1), an outer circumferential surface of the stator (2) being configured in the circumferential direction with a radial profile, into which the housing (11) protrudes in such a way that a form-fitting connection of both components is produced in the circumferential direction.

Description

FIELD OF THE INVENTION

The invention relates to an apparatus for the variable setting of the control times of gas exchange valves of an internal combustion engine, having a stator and an output element which is arranged coaxially with respect to the former, the two components being mounted such that they can rotate with respect to one another, and having a housing which is configured separately with respect to the stator and with respect to the output element and which surrounds the stator and the output element at least partly.
In internal combustion engines, camshafts are used to actuate the gas exchange valves. Camshafts are attached in the internal combustion engine in such a way that cams which are attached to them bear against cam followers, for example cup tappets, drag levers or valve rockers. If a camshaft is set in rotation, the cams roll on the cam followers which in turn actuate the gas exchange valves. Both the opening duration and the opening amplitude, and also the opening and closing times of the gas exchange valves, are therefore fixed by the position and the shape of the cams.
Modern engine concepts tend to design the valve timing mechanism in a variable manner. Firstly, the valve stroke and the valve opening duration are to be designed to be variable, extending as far as the complete switching-off of individual cylinders. For this purpose, concepts are provided such as switchable cam followers or electrohydraulic or electric valve actuating systems. Furthermore, it has proven advantageous to be able to influence the opening and closing times of the gas exchange valves during operation of the internal combustion engine. Here, it is particularly desirable to be able to influence the opening and closing times of the inlet and the outlet valves separately, in order, for example, to set a defined valve overlap in a targeted manner. As a result of the setting of the opening and closing times of the gas exchange valves as a function of the current range of the characteristic diagram of the engine, for example as a function of the current rotational speed or the current load, the specific fuel consumption can be reduced, the exhaust-gas behaviour can be influenced positively, and the engine efficiency, the maximum torque and the maximum power output can be increased.
The above-described variability of the valve control times is achieved by a relative change in the phase position of the camshaft with respect to the crankshaft. Here, the camshaft is usually drive-connected to the crankshaft via a chain drive, belt drive, gearwheel drive, or drive concepts which function in an identical manner. An apparatus for changing the control times of an internal combustion engine, also called a camshaft adjuster in the following text, is attached between the chain drive, belt drive or gearwheel drive which is driven by the crankshaft and the camshaft, which apparatus transmits the torque from the crankshaft to the camshaft. Here, this apparatus is configured in such a way that, during operation of the internal combustion engine, the phase position between the crankshaft and the camshaft is maintained reliably and, if desired, the camshaft can be rotated in a defined angular range with respect to the crankshaft.
Belt-driven camshaft adjusters are usually arranged outside the cylinder head. It is to be noted here that the camshaft adjuster must be sealed off completely with respect to the surroundings, in order to prevent leakage of engine oil into the engine compartment. Any leakage oil which occurs must be collected and led back into the cylinder head.
In internal combustion engines having in each case one camshaft for the inlet valves and one camshaft for the outlet valves, the said camshafts can be equipped with in each case one camshaft adjuster. As a result, the opening and closing times of the inlet and outlet valves can be shifted temporally relative to one another and the valve overlaps can be set in a targeted manner.
Modern camshaft adjusters are usually seated at the drive-side end of the camshaft. However, the camshaft adjuster can also be arranged on an intermediate shaft, a non-rotating component or the crankshaft. The said camshaft adjuster comprises a drive wheel which is driven by the crankshaft and maintains a fixed phase relationship with respect to the latter, an output part which is drive-connected to the camshaft and an adjusting mechanism which transmits the torque from the drive wheel to the output part. In the case of a camshaft adjuster which is not arranged on the crankshaft, the drive wheel can be configured as a chain sprocket, a belt pulley or a gearwheel and is driven by the crankshaft by means of a chain drive, a belt drive or a gearwheel drive. The adjusting mechanism can be operated electrically (by means of a driven three-shafted gear mechanism), hydraulically or pneumatically.
One preferred embodiment of hydraulic camshaft adjusters is what is known as the rotary piston adjuster. In the latter, the drive wheel is connected fixedly in terms of rotation to a stator. The stator and an output element are arranged concentrically with respect to one another, the output element being connected to a camshaft, an extension of the camshaft or an intermediate shaft with a force-transmitting, form-fitting or material-to-material connection, for example by means of a press fit, a screw connection or welded connection. A plurality of hollow spaces which are spaced apart in the circumferential direction and extend radially outwards starting from the output element are formed in the stator. The hollow spaces are delimited in a pressure-tight manner in the axial direction by side covers. A vane which is connected to the output element and divides every hollow space into two pressure chambers extends into each of these hollow spaces. The phase of the camshaft relative to the crankshaft can be set or maintained by targeted connection of the individual pressure chambers to a pressure-medium pump or to a tank.
In order to control the camshaft adjuster, sensors detect the characteristic data of the engine, such as the load state and the rotational speed. This data is fed to an electronic control unit which, after comparison of the data with an engine data map of the internal combustion engine, controls the inflow and the outflow of pressure medium to and from the different pressure chambers.
In order to adjust the phase position of the camshaft with respect to the crankshaft, in hydraulic camshaft adjusters one of the two pressure chambers, which act against one another, of a hollow space is connected to a pressure-medium pump and the other is connected to the tank. As a result, the vane is displaced and the camshaft is therefore rotated directly with respect to the crankshaft by the application of pressure to one chamber and by the pressure relief of the other chamber. In order to maintain the phase position, both pressure chambers are either connected to the pressure-medium pump or are disconnected both from the pressure-medium pump and from the tank.
The pressure-medium flows to and from the pressure chambers are controlled by means of a control valve, usually a 4/3-way proportional valve. A valve housing is provided with in each case one connection for the pressure chambers (working connection), one connection to the pressure-medium pump and at least one connection to a tank. An axially displaceable control piston is arranged within the valve housing which is of substantially hollow-cylindrical configuration. The control piston can be moved axially into every position between two defined end positions by means of an electromagnetic actuator counter to the spring force of a spring element. Furthermore, the control piston is provided with annular grooves and control edges, as a result of which the individual pressure chambers can be connected optionally to the pressure-medium pump or the tank. A position of the control piston can likewise be provided, in which position the pressure chambers are disconnected both from the pressure-medium pump and also from the pressure-medium tank.
DE 199 08 934 A1 has disclosed an apparatus of this type. Here, it is an apparatus of the rotary piston construction type. A stator is mounted rotatably on an output element which is connected fixedly in terms of rotation to a camshaft. The stator is configured with recesses which are open towards the output element. Compensation washers are provided in the axial direction of the apparatus, which compensation washers delimit the recesses in the axial direction in a sealing manner. The recesses are closed in a pressure-tight manner by the stator, the output element and the compensation washers and therefore form pressure spaces. Vanes which extend into the recesses are formed on the outer circumferential face of the output element. The vanes are configured in such a way that they divide the pressure spaces into in each case two pressure chambers which act against one another. The phase position of the output element with respect to the stator and therefore of the camshaft with respect to the crankshaft can be maintained or adjusted optionally by introducing or discharging pressure medium to or from the pressure chambers. For this purpose, a device is provided for supplying pressure medium having pressure-medium lines and a control valve.
The stator, the output element and the compensation washers are encapsulated by a two-part housing which is connected fixedly in terms of rotation to a drive wheel which is configured as a toothed belt pulley by means of fastening means.
The flat bases of the housing halves ensure pressure-tight contact of the compensation washers with the stator and the output element.
Furthermore, the drive torque of the crankshaft is transmitted with a friction fit to the stator via the drive wheel and the bases of the compensation washers. As an alternative, it is proposed that the side faces of the stator have a profile, as a result of which an additional form-fitting connection can be attained.
In this embodiment, a large number of components are required to realize the apparatus, as a result of which increased assembly expenditure and therefore manufacturing costs occur. Furthermore, the above-described transmission of the torque from the drive wheel to the stator involves increased manufacturing expenditure which has a negative effect on the costs of the apparatus.

SUMMARY OF THE INVENTION

The invention is therefore based on the object of avoiding these described disadvantages and therefore of proposing an apparatus for the variable setting of the control times of gas exchange valves of an internal combustion engine, in which the number of components and therefore the assembly complexity and the manufacturing costs of the apparatus are reduced. Furthermore, the apparatus is to be improved in such a way that the transmission of the torque of the crankshaft to the stator is improved and is achieved with less expensive measures.
According to the invention, the object is achieved in that an outer circumferential surface of the stator is configured in the circumferential direction with a radial profile, into which the housing protrudes in such a way that a form-fitting connection of both components is produced in the circumferential direction.
Apparatuses of this type can be provided with a chain sprocket, a belt pulley or a gearwheel and can be drive-connected to the crankshaft via a chain drive, a toothed-belt drive or a gearwheel drive.
If the apparatus is to be driven by means of a toothed belt, the housing is to be configured in such a way that it prevents pressure-medium escaping from the apparatus.
Here, there can be provision for at least one pressure space to be formed between the stator and the output element, the housing to comprise at least two housing elements, and at least one flat section of the housing which stands perpendicularly with respect to the axial direction of the apparatus to act as a sealing face for the pressure space in the axial direction.
In developments of the invention, the stator and/or at least one of the housing elements can be configured as a sheet-metal part which is formed without cutting. As an alternative, the stator can be of solid configuration, for example as a sintered component.
If the stator and/or the at least one housing element are configured as a sheet-metal part which is formed without cutting, these components can be manufactured by a deep-drawing process.
The two housing elements can be connected to one another by means of a welded connection, as a result of which the housing prevents pressure medium escaping from the apparatus.
In one advantageous development of the invention, there can be provision for a cylindrical section which extends in the axial direction to be formed on the housing for sealing off the apparatus with respect to a radial shaft sealing ring. In addition, there can be provision for a camshaft to engage into the section, and for a gap to be formed between the internal diameter of the section and the camshaft. As a result, the apparatus can be arranged outside the cylinder head, the section engaging into an opening of the cylinder head and being sealed off with respect to the latter by means of the radial shaft seal. Leakage oil which occurs can be guided back into the cylinder head and therefore into the crankcase via the gap between the section and the camshaft.
In a further advantageous development of the invention, there is provision for shaped elements to be formed on at least one of the housing elements in order to increase the surface area. These shaped elements serve firstly to reinforce the housing, and secondly to increase its surface area, which leads to improved cooling of the apparatus. The shaped elements can be configured, for example, as cooling fins.
The following two objects, inter alia, are achieved by the encapsulation of the stator and the output element by way of a housing. Firstly, the housing serves to close the pressure spaces in the axial direction of the apparatus in a pressure-tight manner. This can take place either indirectly, by pressing sealing washers against the stator, or directly, by the formation of sealing faces on the housing. In the case of apparatuses which are driven by toothed belts and are usually arranged outside the cylinder head, the housing additionally serves as an encapsulation of the apparatus which prevents pressure medium escaping from the apparatus into the engine compartment. Any leakage oil which occurs is collected within the housing and guided back into the engine compartment via an axial section. The output element is usually configured as a sintered component in these embodiments, which sintered component has to be sealed in a work step which follows the shaping process. This work step is usually very time-intensive and therefore cost-intensive.
Sealing work steps of this type can be dispensed with by the configuration of the housing as a sheet-metal part which is formed without cutting and is inherently oil-tight. Furthermore, the number of connecting points to be sealed will be reduced from at least two (between the side covers and the stator) to one (between the housing halves).
In comparison with the apparatus which is described in the prior art, a cost advantage can be achieved by the fact that at least the function of one of the sealing washers is integrated into the housing. To this end, at least one base of a section of the housing of cup-shaped configuration is configured to be flat. This base bears in a pressure-tight manner both against the stator and against the output element in the axial direction.
The housing comprises two housing elements, into which the stator and the output element can be placed. Here, both housing elements can be of cup-shaped configuration. An embodiment with a cup-shaped housing element and a flat housing element is likewise conceivable. The housing elements can be connected to one another by means of connecting means, such as screws or bolts, or with a force-fitting or material-to-material fit. The base of at least one of the cup-shaped sections is flat and configured in such a way that it delimits the pressure spaces which are formed between the stator and the output element in a pressure-tight manner in an axial direction. It is likewise conceivable that the pressure spaces are delimited in both axial directions by flat sections of the housing which stand perpendicularly with respect to the axial direction of the apparatus.
The costs of the apparatus can be reduced considerably by the reduction in the number of components and the associated lower assembly expenditure. Here, the inexpensive manufacture of the housing elements by way of a forming process without cutting, for example a deep-drawing process, likewise has a positive effect.
The use of a stator which is manufactured from a sheet-metal blank in a forming process without cutting is likewise conceivable. A radial profile is formed in the circumferential direction of the stator by the configuration of the stator as a thin-walled shaped sheet-metal part. In this case, the stator comprises radially outer circumferential walls, radially inner circumferential walls and side walls which in each case connect an inner circumferential wall to an outer circumferential wall. This profile can be used to transmit the torque, which is transmitted from the drive wheel to the housing, to the stator. To this end, the internal diameter of the circumferential surface of the cup-shaped section or sections is adapted to the external diameter of the outer circumferential walls. As a consequence, the stator can be accommodated in the housing, the said stator being centred at the same time relative to the housing. Formed recesses are provided between the outer circumferential walls of the stator on the cup-shaped section or sections of the housing element or housing elements, which formed recesses are configured in such a way that they bear against the respective side walls. As a result, a form-fitting connection is produced in the circumferential direction, via which the torque can be transmitted from the housing to the stator. The stator can be manufactured so as to be thinner and therefore lighter and less expensive as a result of the transmission of the torque by means of surfaces which are in contact in the circumferential direction and the increased contact surface area. Moreover, this type of connection can be manufactured considerably more reliably.
Furthermore, the formed recesses in the housing can be used for the engagement of the drive wheel. A connection which is form-fitting in the circumferential direction can also be produced at this point by the shaping of an internal circumferential surface of the drive wheel which is complementary to the external circumferential surface of the housing.
The use of this form-fitting connection between the housing and a stator of solid configuration, for example made from sintered metal, is likewise conceivable. For this purpose, the profile of the external circumferential surface of the stator is advantageously taken into consideration as early as in the shaping die. As a result, no additional costs are produced, whereas the quality of the connection between the stator and the housing can be improved considerably.
The invention is of course also conceivable in apparatuses which are driven by chain sprockets or gearwheels.
In one advantageous development of the invention, a locking device is provided, a locking pin engaging into a slotted guide which is formed on a sealing washer, and the sealing washer being composed of a hardenable steel.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features of the invention result from the following description and the drawings, in which exemplary embodiments of the invention are shown in a simplified manner and in which:
FIG. 1 a shows an internal combustion engine in a purely diagrammatic manner,
FIG. 1 shows a longitudinal section through an apparatus according to the invention,
FIG. 2 shows a plan view of the apparatus according to the invention from FIG. 1, along the line II-II,
FIG. 3 shows a perspective view of a housing element of the apparatus according to the invention according to FIG. 1, and
FIG. 4 shows a plan view of the further apparatus according to the invention, in an analogous manner to that from FIG. 1, along the line II-II.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 a outlines an internal combustion engine 100, a piston 102 which sits on a crankshaft 101 being indicated in a cylinder 103. In the embodiment shown, the crankshaft 101 is connected to an inlet camshaft 106 and an outlet camshaft 107 via in each case one flexible drive 104 and 105, respectively, it being possible for a first and a second apparatus 1 to ensure a relative rotation between the crankshaft 101 and the camshafts 106, 107. Cams 108, 109 of the camshafts 106, 107 actuate an inlet gas exchange valve 110 and the outlet gas exchange valve 111. There can likewise be provision to equip only one of the camshafts 106, 107 with an apparatus 1, or to provide only one camshaft 106, 107 which is provided with an apparatus 1.
FIGS. 1 and 2 show a first embodiment of an apparatus 1 for the variable setting of the control times of gas exchange valves of an internal combustion engine. In the following text, the invention will be explained using an apparatus 1 which is driven by a belt. Apparatuses which are driven by chains or gearwheels are likewise conceivable. The special feature of the apparatuses which are driven by belts lies in their pressure-medium-tight encapsulation which is not necessary in the other embodiments. An adjusting apparatus 1 a essentially comprises a stator 2 and an output element 3 which is arranged concentrically with respect to the former. FIG. 2 shows a plan view of a sealing washer 12, components which lie behind the said sealing washer 12 being indicated by dashed lines.
The output element 3 comprises a wheel hub 4, on the outer circumference of which axially extending vane slots 5 are formed, and five vanes 6 which are arranged in the vane slots 5 and extend radially outwards. Furthermore, the output element 3 is provided with a stepped central hole 4 a, into which a camshaft (not shown) engages in the mounted state of the apparatus 1, from the right in FIG. 1. In the mounted state of the apparatus 1, the latter is connected fixedly in terms of rotation to the camshaft, for example by means of a force-transmitting, frictional, form-fitting or material-to-material connection, or by means of fastening means.
The stator 2 is configured as a thin-walled sheet-metal part, the latter comprising inner circumferential walls 7 and outer circumferential walls 8 which are connected to one another via side walls 9. The inner and the outer circumferential walls 7, 8 extend substantially in the circumferential direction, whereas the side walls 9 extend substantially in the radial direction. The stator 2 is manufactured in one piece from a sheet-metal blank, by means of a forming process without cutting. Here, there can be provision to manufacture the stator 2 without cutting by means of a deep-drawing method, for example from a steel sheet. The stator 2 is mounted rotatably on the output element 3 via the inner circumferential walls 7 which bear against a cylindrical circumferential wall of the output element 3. Starting from the inner circumferential walls 7, the side walls 9 extend substantially in the radial direction outwards and merge into the outer circumferential walls 8. As a result of this construction, a plurality of pressure spaces 10, five in the embodiment shown, are formed which, as described in the following text, are closed off in a pressure-tight manner in the axial direction by a housing 11 or by a sealing washer 12.
The vanes 6 are arranged on the outer circumferential surface of the output element 3 in such a way that in each case one vane 6 extends into a pressure space 10. Here, the vanes 6 bear in a pressure-tight manner against the outer circumferential walls 8 of the stator 2 in the radial direction. For this purpose, spring elements 13 which displace the vanes 6 radially outwards are arranged in the vane slots 5. The width of the vanes 6 is configured in such a way that the vanes 6 bear against the housing 11 or the sealing washer 12 in the axial direction. As a result, it is achieved that each vane 6 divides a pressure space 10 into two pressure chambers 14, 15 which act against one another.
The stator 2 and the output element 3 are arranged within the housing 11 which is configured in such a way that it encapsulates these components in an oil-tight manner. The housing 11 comprises a first housing element 16 which is of substantially cup-shaped configuration and a disc-shaped second housing element 17. The connecting point of the housing elements 16, 17 can be sealed by means of a sealing medium (not shown) or by means of sealing joining processes. In the embodiment shown, a welded connection 16 a is provided which runs in the circumferential direction. The first housing element 16 is arranged on that side of the apparatus 1 which faces the camshaft. A flat section, which stands perpendicularly with respect to the axial direction of the apparatus 1, of a cup-shaped section of the first housing element 16, called the base 18 in the following text, is positioned symmetrically with respect to the rotational axis of the first housing element 16, a cylindrical section 19 which extends in the axial direction being formed. The section 19 serves firstly to accommodate the camshaft (not shown) or a pressure-medium distributor. Secondly, the outer circumferential surface of the cylindrical section 19 can be used as a seat for a radial shaft seal 20 in the case of a belt-driven apparatus 1, which radial shaft seal 20 seals the apparatus 1 with respect to a cylinder head (not shown).
The internal diameter of the substantially cylindrical circumferential surface of the cup-shaped section of the first housing element 16 is adapted to the external diameter of the outer circumferential walls 8 of the stator 2. This ensures a centered accommodation of the stator 2 in the first housing element 16. Furthermore, the substantially cylindrical circumferential surface of the first housing element 16 is provided with formed recesses 21 which extend radially inwards between adjacent outer circumferential walls 8 of the stator 2. The formed recesses 21 are configured in such a way that they bear against the respective two side walls 9 of the stator 2 in the circumferential direction. As a result, a form-fitting connection is produced in the circumferential direction between the stator 2 and the housing 11, as a result of which the two components are connected to one another fixedly in terms of rotation. Here, there can be provision for the formed recesses 21 to extend as far as the inner circumferential walls 7 of the stator 2, or for the formed recesses 21 to engage only partly into this hollow space.
Furthermore, a radially extending collar 22, in which holes 23 are formed, is formed on that end of the first housing element 16 which faces away from the camshaft.
The second housing element 17 is arranged coaxially with respect to the first housing element 16, the outer circumferential surface of the second housing element 17 being configured in a complementary manner to the collar 22 of the first housing element 16. The two housing elements 16, 17 and a drive wheel 24 which is configured as a belt pulley are connected to one another fixedly in terms of rotation by means of connecting means 24, screws in the exemplary embodiment shown. As an alternative, force-transmitting or material-to-material connecting methods can also be provided. In addition, the inner circumferential surface of the drive wheel 24 can be configured in a complementary manner to the outer circumferential surface of the first housing element 16, as a result of which the drive wheel 24 engages into the formed recesses 21 of the first housing element 16 and the two components are therefore connected in a form-fitting manner in the circumferential direction. The introduction of the torque which is transmitted from the crankshaft to the drive wheel 24 can then be transmitted via the form-fitting connections between the drive wheel 24 and the formed recesses 21 of the first housing element 16 and, furthermore, via the form-fitting connections between the formed recesses 21 and the stator 2 to the latter. This form-fitting connection of the components in the circumferential direction replaces the frictional connection which is described in the prior art between the bases of the housing elements and an axial side face of the stator 2. The transmitted forces therefore act in the direction of the connection between the components and over a considerably greater surface area, as a result of which the forces can be transmitted reliably. The transmitted force is distributed to a greater connecting surface area, as a result of which the stator 2 can be configured with thinner walls. As a result, in addition to the functional safety of the torque transmission, the weight of the apparatus 1 and therefore its moment of inertia and also the costs are reduced.
As shown in FIG. 1, the second housing element 17 can be provided with a central opening 17 a. In one embodiment of the apparatus 1, in which the output element 3 is fastened to the camshaft by means of a central screw, this opening 17 a serves as an engagement opening for a tool in order to tighten the central screw. In this case, the opening 17 a can be closed in an oil-tight manner by means of a cover (not shown) after assembly of the apparatus 1 on the camshaft.
Embodiments of the apparatus 1 are likewise conceivable, in which the second housing element 17 is configured without an opening 17 a.
Shaped elements 11 a are formed on the second housing element 17, which firstly reinforce the component and secondly increase the surface area of the housing 11 and therefore contribute to improved cooling. An embodiment of the shaped elements 11 a as cooling fins is particularly advantageous.
FIG. 3 shows a perspective view of the first housing element 16. The formed recesses 21 are clearly visible, which engage inwardly into the hollow spaces of the stator 2 in the radial direction. On the outer circumferential surface, the formed recesses 21 likewise make engagement of the drive wheel 24 possible, the inner circumferential surface of the drive wheel 24 advantageously being adapted to the outer circumferential surface of the first housing element 16.
As can be seen in FIG. 1, the pressure spaces 10 are closed in a pressure-tight manner in the axial direction on that side of the apparatus 1 which faces the camshaft by the base 18 of the first housing element 16. For this purpose, the base 18 of the first housing element 16 is of flat configuration and is arranged in such a way that it adjoins the output element 3 or the stator 2 directly in the axial direction. A sealing washer 12 is arranged on that side of the apparatus 1 which faces away from the camshaft between the second housing element 17 and the stator 2 or the output element 3. The outer circumference of the sealing washer 12 is adapted to the inner contour of the first housing element 16, as a result of which the latter is connected fixedly in terms of rotation to the housing 11 and therefore to the stator 2. It bears both against the output element 3 and against the stator 2, at least in the region of the pressure spaces, and is pressed against the stator 2 by means of the second housing element 17, as a result of which the pressure spaces 10 are closed in a pressure-tight manner in this axial direction. As an alternative, it is likewise conceivable to omit this sealing washer 12 and to seal the pressure spaces 10 axially by way of the second housing element 17. For this purpose, this second housing element 17 would likewise have to be of flat configuration.
As a result of the fact that the base 18 of the first housing element 16 is used as a sealing face for the pressure spaces 10 in the axial direction, a second sealing washer can be omitted, as a result of which the number of components and therefore the assembly expenditure and the costs of the apparatus 1 can be reduced. These advantages could be increased by virtue of the fact that the sealing washer 12 is likewise omitted and the pressure spaces are likewise sealed in this axial direction by the second housing element 17.
Furthermore, the apparatus 1 is provided with two groups of pressure- medium lines 25, 26 which, starting from the central hole 4 a of the output element 3, extend outwards in the radial direction. Here, the first pressure-medium lines 25 open into the first pressure chambers 14, whereas the second pressure-medium lines 26 open into the second pressure chambers 15. Pressure medium can be optionally fed to or guided away from the first or the second pressure chambers 14, 15 by means of a pressure-medium distributor which is arranged in the central hole 4 a of the output element 3, or alternatively by means of a control valve, via the pressure- medium lines 25, 26. A pressure gradient can therefore be built up between the first and second pressure chambers 14, 15, as a result of which the vanes 6 are displaced in the circumferential direction and the relative phase position of the output element 3 with respect to the stator 2 can therefore optionally be set in a variable manner or maintained. As a result of the adjustment of the phase position between the output element 3 which is connected fixedly in terms of rotation to the camshaft and the stator 2 which is drive-connected to the crankshaft, the phase position between the crankshaft and the camshaft can be influenced in a targeted manner and the control times of the gas exchange valves can therefore be influenced relative to the position of the crankshaft.
Furthermore, FIG. 2 shows an apparatus 27 for restricting the angle of rotation, which is realized by a pin 28 which is connected fixedly in terms of rotation to the output element 3 and a cut-out 29 which is formed on the sealing washer 12. The pin 28 engages into the cut-out 29, the cut-out 29 extending in the circumferential direction in such a way that the pin 28 comes to bear against a substantially radially extending wall of the cut-out 29 in both extreme positions of the output element 3 with respect to the stator 2. As a result, it is prevented that the vanes 6 dip into the transition region between the outer circumferential walls 8 and the side walls 9. This prevents the vanes 6 from jamming on the radii which are formed there.
In the event of insufficient pressure-medium supply to the apparatus 1, for example during the starting phase of the internal combustion engine or during idling, the output element 3 is moved in an uncontrolled manner relative to the stator 2 on account of the alternating torques and drag torques which the camshaft exerts on the said output element 3. In a first phase, the drag torques of the camshaft displace the output element 3 relative to the stator 2 in the circumferential direction which lies opposite to the rotational direction of the stator 2, until this movement is stopped by the apparatus 27 for restricting the angle of rotation. Subsequently, the alternating torques which the camshaft exerts on the output element 3 lead to the output element 3 and therefore the vanes 6 oscillating to and fro in the pressure spaces 10, until at least one of the pressure chambers 14, 15 is filled completely with pressure medium. This leads to higher wear and to noise development in the apparatus 1. Furthermore, the phase position between the output element 3 and the stator 2 oscillates at a high amplitude in this operational phase, which leads to irregular operation of the internal combustion engine. In order to prevent this, a locking device 30 is provided in the apparatus 1. The said locking device 30 comprises a locking pin 31 which is arranged in a recess of the output element 3 and is displaced in the direction of the sealing washer 12 by means of a spring. A slotted guide 32 is formed on the sealing washer 12, into which slotted guide 32 the locking pin 31 is displaced in a maximum early position or a maximum late position of the output element 3 with respect to the stator 2. In this case, the locking pin 31 bears against the radial delimiting walls of the slotted guide 32, the said locking pin 31 extending at the same time into the receptacle which is formed on the output element 3. As a result, a form-fitting, mechanical connection is produced between the output element 3 and the stator 2 in a relative phase position which corresponds to an optimum position for starting and/or idling of the internal combustion engine. In addition to the locking of the output element 3 to the stator 2 in one of the maximum end positions, there can also be provision for both components to be locked relative to one another in a centre position. The sealing washer 12 is advantageously configured from a hardenable steel. The sealing washer 12 is subjected to a hardening process after being formed, as a result of which it can absorb the forces which are transmitted via the locking pin 31 in a functionally reliable way. This leads to an increased service life of the apparatus 1.
Furthermore, means are provided, in order to displace the locking pin 31 back into the receptacle when the apparatus 1 is supplied sufficiently with pressure medium, and therefore to cancel the locking action. In the embodiment shown, there is provision for pressure medium to act on the slotted guide 32 via pressure-medium channels 33. The pressure-medium channels 33 are configured as grooves which are formed in the side face of the output element 3 and extend from at least one of the pressure chambers 14, 15 as far as the slotted guide 32.
The pressure medium which is guided into the slotted guide 32 displaces the locking pin 31 back into the receptacle counter to the force of the spring, as a result of which the fixed phase relationship between the output element 3 and the stator 2 is cancelled.
Here, there is provision for the pressure-medium channels 33 to communicate with the slotted guide 32 only in a defined small angular interval of the phase position between the stator 2 and the output element 3.
The housing 11 is advantageously configured as a sheet-metal housing, the two housing elements 16, 17 being manufactured from a sheet-metal blank by means of in each case one forming process without cutting. Here, techniques such as deep-drawing processes are to be considered, for example. The reliable sealing action of the apparatus 1 is ensured by the formation of the housing 11 from a steel-sheet blank, as a result of which the apparatus 1 can be used as a belt-driven camshaft adjuster. Camshaft adjusters of this type are usually arranged outside the cylinder head, as a result of which reliable sealing of the apparatus 1 becomes necessary. Leakage oil which occurs is collected by the formation of the housing 11 as a sheet-metal formed part within the apparatus 1, and can be returned into the cylinder head by channels which are formed on the cylindrical section 19. As an alternative, an annular gap can be formed between the section 19 and the camshaft, in order to guide leakage oil back into the cylinder head. The first housing element 16 is advantageously sealed relative to the cylinder head via a radial shaft seal 20 which is arranged on the section 19.
Expensive post-treatment for sealing the output element 3 which is normally configured as a porous sintered component can be omitted as a result of the encapsulation of the stator 2 and the output element 3 within the housing 11. Any small leakage which occurs as a result of the sintered material or at the sealing locations is held within the apparatus 1 by the housing 11 and can be returned into the cylinder head.
In the embodiment in which the pressure spaces 10 are closed in a pressure-tight manner by means of a sealing washer 12 on that side of the apparatus 1 which faces away from the camshaft, this sealing washer 12 can at the same time serve as a compensation washer, in order to compensate for any tolerances which occur of the two housing elements 16, 17.
FIG. 4 shows a further embodiment of an apparatus 1 according to the invention. In this illustration, the sealing washer 12 has been removed. This embodiment is largely identical to the first embodiment, for which reason identical components have been provided with identical reference numerals. In contrast to the first embodiment, the stator 2 a is not configured here as a thin-walled sheet-metal formed part, but as a solid component. Here, this can be, for example, a stator 2 a made from a sintered material. In this embodiment, the housing 11 fulfils the same functions as in the first embodiment (torque transmission, sealing of the pressure spaces 10), as a result of which the same advantages are attained. The formed recesses 21 engage into indentations 21 a which are formed on the stator 2 a. These indentations can be formed on the sintered component without additional costs by virtue of them already being taken into consideration in the forming die.

LIST OF REFERENCE NUMERALS

1 Apparatus
1 a Adjusting apparatus
2 Stator
2 a Stator
3 Output element
4 Wheel hub
4 a Central hole
5 Vane slot
6 Vane
7 Inner circumferential wall
8 Outer circumferential wall
9 Side wall
10 Pressure space
11 Housing
11 a Shaped element
12 Sealing washer
13 Spring element
14 First pressure chamber
15 Second pressure chamber
16 First housing element
16 a Welded connection
17 Second housing element
17 a Opening
18 Base
19 Section
20 Radial shaft seal
21 Formed recesses
22 Collar
23 Holes
24 Drive wheel
25 First pressure-medium line
26 Second pressure-medium line
27 Apparatus for restricting the angle of rotation
28 Pin
29 Cut-out
30 Locking device
31 Locking pin
32 Slotted guide
33 Pressure-medium channel
100 Internal combustion engine
101 Crankshaft
102 Piston
103 Cylinder
104 Flexible drive
105 Flexible drive
106 Inlet camshaft
107 Outlet camshaft
108 Cam
109 Cam
110 Inlet gas exchange valve
111 Outlet gas exchange valve

Claims

1. Apparatus for the variable setting of the control times of gas exchange valves of an internal combustion engine, comprising:

a stator and an output element which is arranged coaxially with respect to the stator,

the stator and the output element being mounted such that they can rotate with respect to one another,

a housing which is configured separately with respect to the stator and with respect to the output element and which surrounds the stator and the output element at least partly, wherein

an outer circumferential surface of the stator is configured in the circumferential direction with a radial profile, into which the housing protrudes in such a way that a form-fitting connection of both components is produced in the circumferential direction.

2. Apparatus according to claim 1, the housing prevents pressure medium from escaping from the apparatus.

3. Apparatus according to claim 1, wherein at least one pressure space is formed between the stator and the output element, the housing comprises at least two housing elements, and at least one flat section of the housing which stands perpendicularly with respect to the axial direction of the apparatus acts as a sealing face for the pressure space in the axial direction.

4. Apparatus according to claim 1, wherein the stator is configured as a sheet-metal part which is formed without cutting.

5. Apparatus according to claim 4, wherein the stator is manufactured by a deep-drawing process.

6. Apparatus according to claim 3, wherein at least one of the housing elements configured as a sheet-metal part which is formed without cutting.

7. Apparatus according to claim 6, wherein at least one housing element is manufactured by a deep-drawing process.

8. Apparatus according to claim 1, wherein the two housing elements are connected to one another by means of a welded connection.

9. Apparatus according to claim 1, wherein a cylindrical section which extends in the axial direction is formed on the housing for sealing off the apparatus with respect to a radial shaft sealing ring.

10. Apparatus according to claim 9, wherein a camshaft engages into the section, and in that a gap is formed between the internal diameter of the section and the camshaft.

11. Apparatus according to claim 1, wherein shaped elements are formed on at least one of the housing elements in order to increase the surface area.

12. Apparatus according to claim 1, wherein a locking device is provided, a locking pin engaging into a slotted guide which is formed on a sealing washer, and the sealing washer being composed of a hardenable steel.