DE4212253C1 - Engine valve timing and stroke adjustment - has stroke control piston spring-loaded against valve in cylinder separate from rocker-supporting cylinder - Google Patents

Abstract

The piston (21) of the control unit (19), which is mounted on the cylinder head separate from the supporting cylinder (10), is held by a return spring (22) against the engine valve (9). A regulator (36) controls the flow of the medium under pressure to and from the pressure chamber (16) of the supporting cylinder (10) dependent on the position of the calibration (35). The pressure chamber (16) is in flow communication with the pressure medium supply whereby the regulator can hinder the flow from the chamber so long as the valve stroke remains below the marker (35). Flow of the pressure medium is allowed so long as the valve is opened further than the marker. ADVANTAGE - Simplicity, and stepless control of engine load without throttle butterfly.

Description

The invention relates to a device for adjusting Valve control times and valve lift with a cam-controlled Valve train of an internal combustion engine.

From DE-OS 40 00 531 an adjustment device for Ver change in valve timing and valve lift known at a cylinder-piston arrangement consisting of a cylinder with control bore and a piston with angled control edge, serves as an adjustable support for a rocker arm or acts directly on the valve. The adjustment of the cylinder col ben arrangement is done by rotating the piston, causing the sloping control edge the control hole when pushing the Device locked from a predetermined position and thus further pushing together is prevented.

The disadvantage of this device is that only symme tric valve lift curves can be displayed. Au In addition, a reduction in the valve opening time leads automatically to reduce the valve lift.

The object of the invention is to provide a device for To create setting of valve timing and valve lift, with the simple means with the elimination of a throttle valve variable, stepless engine load control is made possible, being in the region of the valve opening by the cam shape  Fixed course of the valve lift curve for everyone Control times and for all valve strokes, with the exception of the Nullhu bes, is preserved.

The object is achieved by the features of the kenn drawing part of the main claim solved.

By dividing the device into a control and a separate actuating pistons it is possible to set one by the cam shape Fixed valve lift curve up to a specified one Point to go through and only then in the course of this Ven intervention curve by either closing the door gear initiated prematurely or the valve lift up to the cam shape-related closing process kept at a constant value becomes. Because here the control piston is in direct operative connection with the valve stem, the degree of opening of the gas exchange valve as a direct control parameter for the position of the Support device can be used.

Since the device according to the invention is zero-stroke capable, Using such a variable engine control, the engine load even without the use of a throttle valve be put. In addition to the elimination of the Throttle valve, an improvement in fuel consumption, the Torque curve and exhaust gas values.

When using a pressure accumulator, unwanted pressure can occur peaks in the engine oil circuit can be avoided, as the supply hydraulic system only the amount of leakage oil from the engine oil circuit must be supplied. In addition, this will during the Closing stroke quickly oil, which is also under increased Pressure is provided.  

The arrangement of a second inclined control edge in a second Angular range of the control piston makes it possible to change the gas Selventil also during the cam curve-related closing movement close quickly. To make an unwanted The gas exchange valve closes during the opening movement prevent the control unit until the Maximum valve stroke disabled.

The use of an electronic encoder to record the Valve stroke and an evaluation device for controlling the Finally, the actuator has the advantage that further loading drive parameters and additional control interventions without any problems can be realized.

Further advantages of the invention emerge from the subclaims and the description.

Embodiments of a device according to the invention described below with reference to the drawing, wherein in individual

Fig. 1 shows a first embodiment of a device according to the invention partly in section,

Fig. 2 valve lift curves when using the apparatus of Fig. 1 at different angular positions of the STEU erkolbens,

Fig. 3 shows a second embodiment of a device according to the invention partly in section,

Fig. 4 shows a third embodiment of a device according to the invention partly in section,

Fig. 5 valve lift curves when using the device of Fig. 3 or Fig. 4 at different angular positions of the control piston and

FIG. 6 shows a further exemplary embodiment of a device according to the invention, with which valve lift curves according to FIG. 2 can be shown.

Fig. 1 shows the valve train 1 of an internal combustion engine, not shown. A trained as a rocker arm 2 Ven tilbetschlußhebel, the tread 3 is acted upon by the control cam 4 of a camshaft 5 is supported at one end with a base 6 on a support device 7 , while the other end is operatively connected to a valve stem 8 of a gas exchange valve 9 . The support device 7 consists of a support cylinder 10 in which a support piston 11 is movably guided against the force of a return spring 12 . In the bottom of the support cylinder 10 is a return valve 14 provided with a Rückschlagven valve 13 , which is acted upon by an engine oil pressure line 15 with oil. In Be a pressure chamber 16 , which forms between the support piston 11 and the bottom of the support cylinder 10 , a bottom 17 is provided in the wall of the support cylinder 10 in the immediate vicinity of the cylinder bottom.

On the valve stem 8 in the direction of the valve longitudinal axis 18 opposite side of the rocker arm 2 , a control unit 19 is arranged. The control unit 19 consists of a control housing 20 in which a control piston 21 is movably guided against the force of a second return spring 22 . In the lateral surface of the control piston 21 , a cutout 23 is introduced , the extent of which increases in the direction of the longitudinal axis of the piston over the radial circumference of the control piston 21 , so that the rocker arm 2 facing edge of the cutout 23 forms a helically inclined control edge 24 . In addition, in the end of the control piston 21 facing the rocker arm 2, a ring gear 25 in which a control rod 26 engages to adjust the desired valve stroke H _is arranged.

In the control housing 20 , a control bore 27 , and an outlet bore 28 is provided, the control bore 27 being arranged in the region between the outlet bore 28 and the rocker arm 2 facing end of the control piston 21 . The control bore 27 is connected via a first section 29 of a control line 30 with the bore 17 in the support device 7 and the outlet bore 28 via a second section 31 of the control line 30 with a pressure accumulator 32 . In addition, a transverse channel 34 secured by a second check valve 33 runs between the first section 29 and the second section 31 of the control line 30 . The control bore 27 forms, together with the outlet bore 28 and the inclined control edge 24 provided as a marking 35 , an actuator 36 .

During operation of the internal combustion engine, the control cam 4 presses on the running surface 3 of the rocker arm 2 in the course of one revolution of the camshaft 5 . As a result, the support piston 11 is loaded and pressed down against the force of the return spring 12 . The check valve 13 is closed by the resulting oil pressure, so that no oil can flow out through the engine oil pressure line 15 . The bore 17 is in flow connection with the control bore 27 via the control line 30 . If this is closed by the control piston 21 , the oil cannot flow out here either, so that the position of the support piston 11 is fixed. If the control cam 4 now presses the rocker arm 2 further down, it is pivoted against the support piston 11 , as a result of which the valve stem 8 moves downward and the gas exchange valve 9 is thus opened. The control piston 21 follows, due to the force of the return spring 22 , the movement of the rocker arm 2 and also moves downward until the diagonal control edge 24 arranged on the control piston 21 releases the control bore 27 . Thus, the oil from the support device 7 through the bore 17 , the first part 29 of the control line 30 , the control bore 27 , the cutout 23 , the outlet bore 28 and the second portion 31 of the control line 30 flow into the pressure accumulator 32 .

In this case, the movement of the control cam 4 causes the rocking lever 2 to lower the support piston 11 instead of a pivoting movement, so that the gas exchange valve 9 is not opened any further. However, if the gas exchange valve 9 closes again, the control piston 21 is pressed upwards, the inclined control edge 24 closing the control bore 27 again and thus preventing a further outflow of the oil from the support device 7 . Through this interplay of opening and closing the control bore 27 , the Ven tilhub _{is kept} approximately constant at a value H des corresponding to the position of the inclined control edge 24 until the falling course of the control cam 4 mechanically initiates the closing movement of the gas exchange valve 9 . The control piston 21 moves by the force of the Ven tilfeder not shown up and closes the control bore 27th

At the same time, the support piston 11 is relieved, as a result of which oil flows from the pressure accumulator 32 into the support cylinder 10 against the now opened second check valve 33 . If the game between the control cam 4 and the rocker arm 2 , be respectively between the rocker arm 2 and the support piston 11 , for example due to leaks in the hydraulic system, increases, can be relieved of the support device 7 through the open check valve 13 oil from the engine oil - Pressure line 15 flow into the support cylinder 10 , so that the support device 7 also works as a play compensation element.

The desired valve target stroke H _{should of} the gas exchange valve 9 can be set by rotating the control piston 21 with the aid of the control rod 26 , which engages in the ring gear 25 arranged on the control piston 21 , by rotating the control piston 21 between the basic position = 0 degrees and the maximum position = 360 degrees valve strokes between zero and _maximum valve lift H _max can be displayed. For this purpose, the stroke of the support device 7 is designed so that the entire stroke of the control cam 4 can be absorbed.

In order to brake the movement of the control piston 21 , rocker arm 2 and gas exchange valve 9 at the end of the partial stroke, a damping device 37 is integrated in the control unit 19 . For this purpose, the end of the control piston 21 designed as a brake piston 38 has a decreasing radial cross section in its end region facing away from the gas exchange valve 9 , so that between the brake piston 38 and an outlet bore 39 arranged in the control housing 20 there is a narrowing annular gap with increasing stroke height of the brake piston 38 40 trains. The outlet bore 39 is connected via a channel 41 to the engine oil pressure line 15 or a further pressure accumulator. In the ceiling of the control housing 20 is also an inlet bore 42 which is in flow connection with the engine oil pressure line 15 and is secured by a further check valve 43 . Through the inlet bore 42 flows during the opening movement of the gas exchange valve 9 with the check valve 43 now open, oil from the engine oil pressure line 15 into the space between the brake piston 38 and the ceiling of the control housing 20 . During the closing movement, this oil is then, with the check valve 43 now closed, pressed out via the annular gap 40 , which narrows with increasing lifting height, and the outlet bore 39 , as a result of which a targeted braking effect can be achieved.

In addition, a small throttle bore 44 , which is also connected to the engine oil pressure line 15, can be arranged in the ceiling of the control housing 20 for venting the entire control and braking system. The cross section of the throttle bore 44 is chosen so that the in the closing movement of the gas exchange valve 9 through the throttle bore 44 from flowing oil does not affect the braking effect of the brake piston 38 . In addition, an annular channel 45 can be provided in the lower region of the control piston 21 , which is used at the same time for lubricating the control piston 21 and for receiving high-pressure leakage oil from the cutout 23 and also via a channel 46 with the engine oil pressure line 15 connected is. Finally, the space between the storage piston 47 and the ceiling of the storage cylinder 48 for damping via another channel 49 with oil from the engine oil pressure line 15 be opened. At the same time, however, this leads to the pressure fluctuations in the engine oil pressure line 15 increasing further.

FIG. 2 shows valve lift curves of the device from FIG. 1 for different angles of rotation of the control piston 21 . The solid line corresponds to an angle of rotation of 360 degrees, which corresponds to a _maximum valve lift H _max , or a permanently closed control bore 27 . As the angle of rotation decreases (dashed lines), the valve lift decreases. It can be seen in FIG. 2 that the start of the stroke and the characteristic of the elevation do not change for all the valve lift curves possible within the cam lift curve. All valve lift curves follow the course of the valve maximum lift curve to the point where the oblique control edge 24 releases the control bore 27 . From this point, the curve then flattens out and remains at an approximately constant value until the closing movement is finally initiated mechanically by the control cam profile. In addition, it can be clearly seen that a reduction in the valve lift also leads to a shortening of the opening duration of the gas exchange valve 9 .

This is because the support piston 11 remains fixed in its uppermost position at valve _maximum stroke H _max and the gas exchange valve 9 is only completely closed when the entire falling control cam flank has passed. In the case of a partial stroke, however, the support piston 11 is fixed in a lower position, so that the gas exchange valve 9 is closed earlier due to the lower support point 6 .

In Fig. 3, a second embodiment of the device according to the Invention is shown, wherein the same parts are identified with the same reference numerals as in Fig. 1. In contrast to FIG. 1, the pressure accumulator 32 has an annular seat 50 arranged in the region of the bottom of the accumulator cylinder 48 , on which the accumulator piston 47 is seated hydraulically in the unloaded state by the force of a return spring 51 . In the area of the radial contact surface between the storage cylinder 48 and the storage piston 47 , an annular channel 52 extends from the ring seat 50 . The ring channel 52 is connected to the pressure chamber 16 via a channel 65 . In addition, a bore 53 is provided which connects the ring channel 52 to the first section 29 of the control line 30 . The outlet bore 28 is connected via the second section 31 of the control line 30 to an inlet opening 54 of the pressure accumulator 32 .

In operation, according to the first exemplary embodiment, the rocking lever 2 is pivoted against the support piston 11 until the inclined control edge 24 of the control piston 21 , which follows the movement of the gas exchange valve 9 , clears the control bore 27 . As a result, oil flows out of the support device 7 through the ring channel 52 of the pressure accumulator 32 and the first section 29 of the control line 30 to the control bore 27 . Since this is no longer closed, the oil can flow through the cutout 23 and the outlet bore 28 into the second section 31 of the Steuerlei device 30 . From there, the oil flows through the inlet opening 54 into the space between the inlet opening 54 and the ring seat 50 . The accumulator piston 47 is lifted off the ring seat 50 by the oil pressure building up. As a result, the oil pressure of the pressure chamber 16 present in the ring channel 52 above the ring seat 50 passes directly below the accumulator piston 47 , as a result of which the piston rises quickly and the support device 7 can thus be completely lowered. As a result, the Gaswechselven valve 9 closes immediately.

When the support device 7 is relieved, due to the falling control cam flank, the support piston 11 is pushed upwards by the force of the return spring 12 . This allows oil to flow back from pressure accumulator 32 and engine oil pressure line 15 into pressure chamber 16 .

In order to be able to control the valve opening time also in the area of the falling control cam flank, the control piston 21 has a second marking 35 designed as an inclined control edge 55 . The two oblique control edges 24 , 55 run on opposite sides of the control piston 21 spirally over 180 degrees, but in opposite directions. The second oblique control edge 55 works together with a second from bore 56 , which is arranged on the abge facing the first outlet bore 28 side of the control bore 27 and is also connected to the second section 31 of the control line 30 . However, using the second inclined control edge 55, the passing through of the opening movement of the gas exchange valve 9 without undesirable flow of control to ensure, is arranged in the control line 30 is a one-way solenoid valve 57, which during remains of the opening closed and is opened only after exceeding the Ventilmaximalhubes H _max.

In operation, the desired opening time of the Gaswechselven valve 9 can in turn be controlled by turning the control piston 21 . If the gas exchange valve 9 is already closed during the opening stroke, the control piston 21 is rotated into a position corresponding to the desired opening time of the first inclined control edge 24 . When the gas exchange valve 9 is completely closed, the lower part of the control piston 21 closes both outlet bores 28 , 56 and the control bore 27 . In the course of the opening stroke, the control piston 21 moves downward and first releases the first outlet bore 28 . However, the oil from the pressure chamber 16 can only flow out when the control bore 27 is also released in the course of the further opening movement. As soon as the control bore 27 is released, the support device 7 is completely relieved and the gas exchange valve 9 is closed immediately.

If, on the other hand, the gas exchange valve 9 is only to be closed in the course of the closing stroke, the control piston 21 is rotated to such an extent that the second inclined control edge 55 takes effect. In addition, the one-way solenoid valve 57 is brought into the closed position. When the gas exchange valve 9 is closed, one or more of the outlet and control bores 28 , 56 , 27 are now open. Through the closed one-way solenoid valve 57 , an outflow of oil from the pressure chamber 16 is prevented ver. During the opening stroke of the gas exchange valve 9 , all outlet and control bores 28 , 56 , 27 are successively closed by the upper part of the control piston 21 . Only when the valve _maximum stroke H _{max is reached} , that is, when all the bores 28 , 56 , 27 are closed, can the one-way magnetic valve 57 be opened. During the closing stroke, the second outlet bore 56 and then the control bore 27 are then released according to the position of the inclined control edge 55 , so that a control flow is possible and the gas exchange valve 9 is closed.

Fig. 4 shows a third embodiment of the device according to the invention, wherein again the same parts are marked with the same reference characters. The valve lift curves that can be set with this device correspond to those of the device from FIG. 3. In contrast to the device from FIG. 3, an electronic displacement sensor 58 is provided here for detecting the valve lift. For this purpose, a solenoid 59 is integrated in the control housing 20 and a metal core 60 serving as a marking 35 is integrated in the control piston 21 . In addition, in the bottom of the support cylinder 10, an additional outlet bore 61 is angeord net, which is connected via the control line 30 to the inlet opening 54 of the pressure accumulator 32 . In the control line 30, the designed as a one-way solenoid valve 57 actuator 36 is arranged. In addition, parallel to the one-way solenoid valve 57, a bypass channel 62 with integrated check valve 63 is provided.

To control the one-way solenoid valve 57 , an evaluation device 64 is provided, which determines a valve closing point from the valve stroke signal of the electronic displacement sensor 58 and from a pedal angle signal, and generates a control signal for opening the one-way solenoid valve 57 after this valve closing point has been reached. By opening the one-way solenoid valve 57 , the accumulator piston 47 is lifted from the ring seat 50 by the oil pressure prevailing in the pressure chamber 16 . Since the oil from the pressure chamber 16 also passes directly through the channel 65 under the accumulator piston 47 , so that the support piston 11 is immediately lowered and thereby the gas exchange valve 9 is closed. The bypass channel 62 is used to return the oil from the pressure accumulator 32 to the pressure chamber 16 more quickly when the support piston 11 is relieved.

Fig. 5 shows valve lift curves of the devices of Fig. 3 and Fig. 4 for different rotational angle of the control piston 21. The solid line a corresponds to an angle of rotation of 360 degrees, which corresponds to a _maximum valve lift H _max or a permanently closed control bore 27 . Various positions of rotation of the control piston 21 are used to represent the valve lift curves denoted by b and c, but in both cases the first inclined control edge 24 is active. Only when the valve lift curve d is the control piston 21 turned so far that the second inclined control edge 55 is activated. In order to prevent unwanted premature closing of the gas exchange valve 9 , the one-way solenoid valve 57 is kept closed until the valve _maximum stroke H _{max is} exceeded. It can also be seen here that the stroke start and the elevation characteristic do not change in all the valve lift curves possible within the cam lift curve. All valve lift curves follow the course of the valve maximum lift curve up to a predetermined point by the oblique control edges 24 , 55 . If this point is reached, the support device 7 is relieved by the release of the control bore 27 and thereby the gas exchange valve 9 is closed.

Finally, FIG. 6 shows a device with which valve lift curves according to FIG. 2 can also be represented using the same method as in FIG. 1. For this purpose, the electronic displacement sensor 58 is used in combination with the evaluation device 64 instead of the control unit 19 according to FIG. 1. It is geous before to arrange the pressure accumulator 32 in the region of the support device 7 . A single-use solenoid valve 57 with a bypass channel 62 and a check valve 63 , which is actuated by the evaluation device 64, can in turn be used as the actuator 36 .

Using multi-valve technology, the gas exchange valves 9 per cylinder can be controlled in pairs or individually via a hydraulic unit in all devices according to the invention. With single valve control, individual gas exchange valves 9 of different cylinders can be controlled via common control rods 26 , so that different valve openings per cylinder, depending on the speed and load, but can be represented uniformly for all cylinders of the internal combustion engine.

Tolerance and wear-related differences in the valve opening from gas exchange valve 9 to gas exchange valve 9 and cylinder to cylinder can be set individually on each hydraulic unit by height or angle correction on the control housing 20 and / or control piston 21 during assembly or, if necessary, readjusted by customer service. In order to keep the moving masses and the temperature-related gap clearance small, all hydraulic components can also be made of ceramic materials.

Claims (12)

1. Device for setting valve timing and valve lift in a cam-controlled valve train of an internal combustion engine with hydraulic support of valves for actuating gas change valves of the valve train provided valve actuating levers on a support device, which comprises a support cylinder provided for each valve actuation lever and a cylinder therein, including a pressure chamber there is a displaceably guided support piston which is acted upon by pressure medium fed into the pressure chamber and a return spring and which bears against a support point of the valve actuation lever, furthermore with a control unit with a control piston which is displaceably guided in a control housing and has a marking, of which from dependent on operating parameters of the internal combustion engine to change the position of the base controlled pressure medium fed into the pressure chamber of the support cylinder or is derived from the pressure chamber, dadu rch characterized in that the control piston ( 21 ) of the control unit ( 19 , 58 ), which is arranged separately from the support cylinder ( 10 ) on the cylinder head, is held by means of a return spring ( 22 ) in contact with the gas exchange valve ( 9 ) and that an actuator ( 36 ) controls the supply or discharge of pressure medium into or out of the pressure chamber ( 16 ) of the support cylinder ( 10 ) depending on the position of the marking ( 35 ). 2. Apparatus according to claim 1, characterized in that the pressure chamber ( 16 ) via a control line ( 30 ), in which the actuator ( 36 ) is arranged, is in flow connection with the pressure medium supply, the actuator ( 36 ) being derived from pressure medium from the pressure chamber (16) verhin changed as long as the valve lift of the gas exchange valve (9) is below the marking (35), the discharge of pressure medium allows and as long as the gas exchange valve (9) is opened further than up to the mark (35). 3. Apparatus according to claim 1, characterized in that the pressure chamber ( 16 ) via a control line ( 30 ), in which the actuator ( 36 ) is arranged, is in flow connection with the pressure medium supply, the actuator ( 36 ) being derived from Pressure medium from the pressure chamber ( 16 ) prevents as long as the valve lift of the gas exchange valve ( 9 ) is below the marking ( 35 ), and releases the pressure medium for the rest of the valve clearance when the valve lift of the gas exchange valve ( 9 ) clears the mark ( 35 ) reached. 4. Apparatus according to claim 2 or 3, characterized in that the control line ( 30 ) for supplying pressure medium with the engine oil pressure line ( 15 ) is in flow connection. 5. Apparatus according to claim 2 or 3, characterized in that the control line ( 30 ) for supplying pressure medium with a pressure accumulator ( 32 ) is in flow connection. 6. The device according to claim 5, characterized in that the pressure accumulator ( 32 ) consists of a storage piston ( 47 ) which is movably guided in a storage cylinder ( 48 ) and hydraulically by the force of a spring ( 51 ) on an annular seat ( 50 ) sits tightly that starting from the ring seat ( 50 ) extends an annular channel ( 52 ) along the lateral surface of the SpeI cher piston ( 47 ) which is connected via a channel ( 65 ) to the pressure chamber ( 16 ), and that the control line ( 30 ) via an inlet opening ( 54 ) opens into the area below the ring seat ( 50 ) in the pressure accumulator ( 32 ). 7. Apparatus according to claim 2 or 6, characterized in that on the control piston ( 21 ) an inclined control edge ( 24 ), which serves as an adjustable by turning the control piston ( 21 ) mark ( 35 ), that is arranged in the area the oblique control edge ( 24 ) a control ( 27 ) and an outlet bore ( 28 ) are introduced as an actuator ( 36 ) in the control housing ( 20 ) that the control line ( 30 ) is interrupted, a portion ( 29 ) of the control line ( 30 ) with the control bore ( 27 ) and the other section ( 31 ) with the outlet bore ( 2 S), and that the inclined control edge ( 24 ) depending on the valve stroke a flow connection between the control ( 27 ) and the outlet bore ( 28 ) releases or closes. 8. The device according to claim 7, characterized in that on the control piston ( 21 ) two oppositely running inclined control edges ( 24 , 55 ) and in the control housing ( 20 ), a second outlet bore ( 56 ) with the first outlet bore ( 28 ) is in flow connection, are arranged such that in a first angular range of the control piston ( 21 ) the first inclined control edge ( 24 ), depending on the valve lift, a flow connection between the control ( 27 ) and the first outlet bore ( 28 ) and in a second Angular range of the control piston ( 21 ) the second inclined control edge ( 55 ) opens or closes a flow connection between the control ( 27 ) and the second outlet bore ( 56 ) and that a one-way solenoid valve ( 57 ) is provided in the control line ( 30 ) which switches off the control unit ( 19 ) until the maximum valve lift is exceeded when the control piston ( 21 ) is in the second angular range. 9. Apparatus according to claim 2 or 3, characterized in that on the control piston ( 21 ) a metal core ( 60 ) is arranged as a marker ( 35 ) which in connection with a housing in the Steuerge ( 20 ) arranged magnetic coil ( 59 ) Valve lift signal generated and that in an evaluation device ( 64 ) from the Ven tilhubsignal and a pedal angle signal as a function of operating parameters, a control signal for actuating the one-way solenoid valve ( 57 ) executed actuator ( 36 ) he testifies. 10. The device according to claim 2 or 3, characterized in that all gas exchange valves ( 9 ) of a cylinder are controlled independently of each other. 11. The device according to claim 2 or 3, characterized in that gas exchange valves ( 9 ) of different cylinders can be controlled in groups. 12. The apparatus of claim 2 or 3, characterized in that the control piston ( 21 ) serves simultaneously as a brake piston ( 38 ) for the damping device designed as a cylinder-piston arrangement ( 37 ) of the gas exchange valve ( 9 ).