Hydraulic unit for arrangement in a rocker arm for a valve train of an internal combustion engine

Abstract

The invention relates to a hydraulic unit (1) for arrangement in a rocker arm for a valve train of an internal combustion engine, characterized in that an adjusting screw (2) carrying hydraulic fluid is provided for screwing into a threaded bore (6) on the rocker arm, wherein a piston (9) which can be acted upon by hydraulic fluid from the adjusting screw and has a valve contact surface (18) for valve lift transmission is movably mounted on the adjusting screw (2) in such a way that, in a hydraulically pressureless state, it can be reset from a contact position for valve lift transmission to a contact-free basic position for valve lift deactivation, and by screwing in the adjusting screw (2), the maximum valve lift that can be transmitted at the rocker arm in the contact position of the piston (9) can be adjusted. The invention further relates to a rocker arm for a valve train of an internal combustion engine, comprising at least one such hydraulic unit (1).

Description

[0001] The invention relates to a hydraulic assembly for arrangement in a rocker arm for a valve train of an internal combustion engine. The invention further relates to a rocker arm for a valve train of an internal combustion engine with at least one such hydraulic assembly.

[0002] WO 2020 / 216474 discloses a hydraulic capsule comprising a hollow capsule body, a hydraulic connection for fluid connection, a plunger, and a locking set, the latter being switchable between a locked state and an unlocked state. An insert is provided for adjusting the locking, and the plunger is configured to push the locking set toward the insert for adjusting the locking.

[0003] The invention is therefore based on the object of proposing a hydraulic unit and a rocker arm of the aforementioned type, which enable valve lift shutoff and adjustment of the maximum transferable valve lift in a structurally simple and space-saving manner.

[0004] The object is achieved by the features of claim 1 and alternatively by the features of claim 10. Further advantageous and claimed embodiments emerge from the respective subclaims, the description and the drawings.

[0005] A hydraulic unit is therefore proposed for arrangement in a rocker arm for a valve train of an internal combustion engine. In order to implement valve lift deactivation in a structurally simple and space-saving manner, an adjusting screw carrying hydraulic fluid is provided for screwing into a threaded hole on the rocker arm. A piston, which can be pressurised with hydraulic fluid from this screw and has a valve contact surface for valve lift transmission, is movably mounted on the adjusting screw so that the piston, in a hydraulically depressurised state, can be reset from a contact position for valve lift transmission to a contact-free basic position for valve lift deactivation. At the same time, by screwing the adjusting screw into the threaded hole on the rocker arm, the maximum transferable valve lift in the contact position of the piston on the rocker arm can be adjusted.

[0006] The piston, which can be directly hydraulically controlled in this way and is movable relative to the adjusting screw, enables valve lift transmission in the force flow between the rocker arm and at least one gas exchange valve of the internal combustion engine through direct contact with the valve contact surface. Valve lift transmission at the valve contact surface through indirect contact via a transmission element, for example, a valve bridge, is also conceivable.

[0007] By returning the piston to its contact-free home position, it is released from contact with the gas exchange valve or the transmission element, allowing the rocker arm to perform an idle stroke. Thus, valve lift deactivation is achievable in the contact-free home position of the piston.

[0008] The proposed hydraulic unit makes it possible to easily implement, in particular, a hydraulically switchable decompression engine brake. Furthermore, the hydraulic control of an early opening of one or more exhaust valves of the internal combustion engine is possible, particularly for heating up an exhaust gas catalytic converter. A late closing of one or more intake valves of the internal combustion engine is also conceivable to increase engine efficiency.

[0009] As a result, a compact hydraulic unit for valve lift deactivation can be achieved, which can be assembled and fastened as a pre-assembled unit with the individual components arranged along an axis in a space-saving manner by screwing it into a threaded hole on the rocker arm, especially on a standardized rocker arm, in a particularly simple and cost-effective manner, without the need for reworking.

[0010] In addition, a complex switching mechanism with additional mechanical or hydraulic switching elements is avoided. This allows for a reduction in components, a simplified design, and a reduction in moving mass, improving valve train dynamics.

[0011] At the same time, the adjusting screw that can be screwed into the threaded hole enables easy adjustment of a predetermined maximum valve lift that can be transmitted to the rocker arm.

[0012] The proposed hydraulic unit is particularly advantageous for use in valve trains for heavy-duty or medium-duty internal combustion engines, especially for trucks, construction vehicles or construction machinery, vans, agricultural equipment, especially tractors, marine and mining equipment. It is particularly advantageous for integration into forged or cast, particularly standardized, rocker arms, saving space and weight with minimal manufacturing and assembly effort.

[0013] In a preferred embodiment of the invention, a check valve is provided for hydraulically controlling the piston. Preferably, the piston can be pressurized with hydraulic fluid via the check valve, so that, in the contact position, a hydraulic pressure cushion can be generated on the piston to transmit the valve stroke. Accordingly, a force from the rocker arm can be transmitted via the piston, which is held rigidly by the hydraulic pressure cushion, to one or more gas exchange valves for valve actuation.

[0014] Preferably, the check valve is preloaded into the open state by valve spring means.

[0015] Thus, by simply deactivating the hydraulic pressure on the piston and returning it to its contact-free home position, the force flow between the rocker arm and the gas exchange valve, and thus the valve lift transmission, can be shut off. The valve spring means ensure a quick and effective opening of the check valve and thus a rapid return of the piston to its contact-free home position for valve lift deactivation. An additional hydraulic valve is thus avoided.

[0016] To adjust the maximum valve lift that can be transmitted by the piston, it is advantageous if the piston is at least partially coaxially enclosed by a sleeve fastened to the adjusting screw and is arranged to be movable relative to this. The relative movement of the piston with respect to the adjusting screw in the contact position of the piston is limited by stop means in the sleeve, so that the stop position can be moved by screwing in the adjusting screw and the maximum valve lift that can be transmitted by the piston can be adjusted. The sleeve can be pressed on, caulked or welded for attachment to the adjusting screw. It is also conceivable for the sleeve to be designed as a single piece with the adjusting screw.

[0017] Preferably, the relative movement of the piston relative to the adjusting screw is limited by a further stop in the sleeve in the contact-free basic position of the piston. Preferably, the piston forms an annular collar at its free end, protruding from the outer diameter, with which it can be applied to the further stop in the sleeve in the contact-free basic position.

[0018] In this way, the stop positions can be moved with the adjusting screw both in the contact position and in the contact-free basic position of the piston when setting the maximum valve stroke that can be transmitted to the piston.

[0019] It is furthermore advantageous if the stop means comprise a stop ring which is fixed in a groove on the outer diameter of the piston and is arranged protruding therefrom, so that it can be moved with the piston relative to the sleeve and can be applied to a stop formed on the sleeve in the contact position of the piston in order to limit the relative movement.

[0020] Preferably, the stop is formed by a second sleeve attached to the free end of the sleeve. This second sleeve can be pressed or welded onto the free end of the first sleeve for attachment.

[0021] In a further preferred particularly simple embodiment of the invention, the piston cooperates with return spring means so that in the hydraulically pressureless state it can be reset by the spring force from the contact position into the contact-free basic position for valve lift shutdown.

[0022] A further advantage can be achieved by arranging the return spring means as a helical compression spring in the sleeve, acting coaxially between the sleeve and the piston. Preferably, the piston is supported in the sleeve by the return spring means, allowing it to move relative to the sleeve, against the sleeve. This allows for simple support of the piston and, at the same time, a particularly compact arrangement.

[0023] Preferably, the return spring means are supported with one spring end on the second sleeve fastened to the free end of the sleeve and with the other spring end on the annular collar formed protruding on the outer diameter of the piston.

[0024] In this way, the second sleeve attached to the first sleeve forms both a spring support for the return spring means and the stop for the piston in the contact position.

[0025] Preferably, depending on the ratio of the size of the hydraulically actuated pressure surface of the piston to the size of the cross-sectional area of ​​the valve opening of the check valve, the spring force of the return spring means is designed to be greater than the spring force of the valve spring means. In this way, the valve spring and return spring means can be further optimized with regard to rapid and effective opening of the check valve and short switching times.

[0026] It is also particularly advantageous if the material for the hydraulic assembly, with the exception of the adjusting screw, is preferably sheet metal, preferably steel. Preferably, the piston and sleeves are each designed as formed sheet metal components and can be manufactured easily and cost-effectively without cutting. The sheet metal design also allows for a particularly lightweight construction with reduced mass and weight, which further improves the switching dynamics of the hydraulic assembly.

[0027] The object of the invention is also achieved by a rocker arm for a valve train of an internal combustion engine with at least one hydraulic unit as described above. The latter can be arranged in a structurally simple manner on the rocker arm for valve lift transmission in the direct power flow between the rocker arm and at least one gas exchange valve of the internal combustion engine. This allows a cost-effective, standardized rocker arm to be designed to be hydraulically switchable for valve lift transmission and deactivation in a variable valve train. In addition, the advantages already described above result.

[0028] Preferably, the hydraulic unit is screwed into a threaded hole on the rocker arm.

[0029] Preferably, it can be reset with a valve contact surface from a contact position for valve lift transmission to at least one gas exchange valve of the internal combustion engine, in a hydraulically depressurized state, to a contact-free basic position for valve lift deactivation. Preferably, the maximum valve lift that can be transmitted in the contact position of the hydraulic unit on the rocker arm can be adjusted by screwing the hydraulic unit into the threaded bore.

[0030] Furthermore, the rocker arm described above can be designed in particular with further features from the following description.

[0031] Further claimed features of the invention will become apparent from the following description and the drawings, which further explain the present invention. They show: Fig. 1 a sectional view of a hydraulic assembly according to the invention for arrangement in a rocker arm for a valve train of an internal combustion engine in the operating state activated for valve lift transmission, Fig. 2 a sectional view of the hydraulic unit in the deactivated operating state for valve lift shutdown, Fig. 3 a perspective view of the hydraulic unit, Fig. 4 a standardized rocker arm with a threaded hole for screwing in the hydraulic unit before assembly, Fig. 5 the rocker arm Fig. 4 with a hydraulic unit screwed into the threaded hole, Fig. 6 the rocker arm Fig. 4 with a hydraulic unit in deactivated operating state in a side view.

[0032] In the Fig. 1 to 3 show various views of a hydraulic assembly 1 according to the invention for arrangement in a rocker arm for a valve train of an internal combustion engine. Fig. 5 and Fig. 6 show an example of a rocker arm according to the invention with such a hydraulic unit 1.

[0033] The hydraulic unit 1 serves to transmit the valve lift to the rocker arm and is arranged in the power flow between the rocker arm and at least one gas exchange valve of the internal combustion engine. Fig. 1 to 3, an adjusting screw 2 conducting hydraulic fluid, which is screwed with a narrow shaft 3 with an external thread 4 into an internal thread 5 of a threaded bore 6 at the end of the valve-side lever arm 7 of the rocker arm between the upper side of the lever facing away from the valve and the lower side of the lever facing the valve. The adjusting screw 2 is fastened with a lock nut 29 at its upper end protruding from the threaded bore 6 on the upper side of the lever facing away from the valve. It protrudes from the threaded bore 6 on the lower side of the lever facing the valve with a free end section 8 which is radially wider on the outer diameter than the shaft 3.

[0034] The hydraulic assembly 1 further comprises a cylindrical piston 9, which is pot-shaped and open on one side. The piston 9 is preferably made of sheet metal. Its open end with the inner diameter or inner circumference is attached to the outer diameter or outer circumference of the protruding free end section 8 of the adjusting screw 2 so that it can move relative to the latter, so that the free end section 8 and the piston 9 delimit a hydraulic pressure chamber 10. The adjusting screw 2 with the free end section 8 and the piston 9 are arranged coaxially to a central axis 11, along which the piston 9 is guided so as to be displaceable relative to the free end section 8 of the adjusting screw 2.

[0035] The pressure chamber 10 is hydraulically connected via a check valve 12 to a hydraulic fluid reservoir 13 formed in the adjusting screw 2. The latter can be pressurized with hydraulic fluid via a hydraulic fluid connection 14 formed in the rocker arm. The hydraulic fluid supply can be switched on and off by a preferably electrically controllable valve (not shown), in particular by a solenoid.

[0036] The hydraulic fluid reservoir 13 is formed partially in the shaft 3 and partially in the end section 8. Adjacent to the hydraulic fluid reservoir 13 is a receiving chamber 15 formed in the end section 8, which is wider than the hydraulic fluid reservoir 13 and open toward the free end of the end section 5. An insert 16 is received in the receiving chamber 15, in which the check valve 12 is formed and held and which simultaneously delimits the hydraulic fluid reservoir 13.

[0037] The pressure chamber 10 can be pressurized with hydraulic fluid via the check valve 12 from the hydraulic fluid reservoir 13, and the piston 9 in the pressure chamber 10 can be pressurized with hydraulic fluid at a pressure surface 17 formed on the inside of its pot-shaped, closed end as a hydraulically effective piston surface. On the outside facing away from the pressure surface 17, it forms a flat valve contact surface 18 with which it can be applied to a gas exchange valve (not shown) to be actuated for valve stroke transmission. It is also conceivable that the piston 9 can be applied with the valve contact surface 18 to a transmission element, for example a valve bridge, for valve stroke transmission. In this way, the piston 9 is arranged directly in the force flow between the rocker arm and the gas exchange valve to be actuated for valve stroke transmission.

[0038] The check valve 12 is designed as a ball valve and has valve spring means 19 that preload the valve ball 21, arranged to close the valve opening 20, into the open state. A helical compression spring arranged in the valve opening 20 is provided as the valve spring means 19.

[0039] Fig. Figure 1 shows the hydraulic unit 1 in the activated state. The piston 9 is guided relative to the housing 3, acting against the spring force of the return spring means 22, with the full piston stroke H extended to the maximum relative to the home position into the contact position for valve stroke transmission. The home position and the contact position of the piston 9 are each indicated by a dashed line. The piston 9, with its valve contact surface 18, is in direct or indirect contact with at least one gas exchange valve (not shown).

[0040] The return spring means 22 are arranged as a helical compression spring coaxially on the outer circumference of the piston 9. When the piston 9 extends into the contact position according to Fig. 1, the return spring means 22 are arranged as in Fig. 1 and preloaded to return the piston 9 to the contact-free basic position for valve lift shutdown, which is shown in Fig. 2 is shown.

[0041] When the piston 9 is in a load-free and hydraulically pressure-free state, the check valve 12 is held open by the spring force of the valve spring means 19. This allows the piston to return to the contact-free basic position according to Fig. 2 by the return spring means 22 acting on the piston 9, hydraulic fluid can be forced out of the pressure chamber 10 via the check valve 12, which is biased into the open state by the valve spring means 19, into the hydraulic fluid reservoir 13. In Fig. 2, the contact position and the basic position of the piston 9 and the reset piston stroke H are each indicated by a dashed line.

[0042] The greater the spring force of the return spring means 22 acting on the piston 9, the faster the hydraulic fluid can be pressed out of the pressure chamber 10 by the piston 9 and the faster the piston 9 can be returned to the contact-free basic position for valve stroke shutdown.

[0043] In order to optimally adjust the force-pressure-effective area ratio of the valve spring means 12 to the return spring means 22, Preferably, depending on the ratio of the size of the pressure surface 17 of the piston 9 and the size of the cross-sectional area of ​​the valve opening 20 of the check valve 12, the spring force of the return spring means 22 is designed to be greater than the spring force of the valve spring means 19. This ensures reliable opening of the check valve 12 to return the piston 9 and, at the same time, a high return speed for valve stroke deactivation.

[0044] To activate the hydraulic unit 1 for valve stroke transmission according to Fig. 1, the previously described electrically controlled valve or solenoid is controlled in such a way that the hydraulic fluid reservoir 13 is supplied with hydraulic fluid via the hydraulic fluid connection 14 in the rocker arm and the pressure chamber 10 via the check valve 12. If the piston 9 is load-free, it is moved by the hydraulic fluid pressure into the contact position for valve stroke transmission according to Fig. 1 pushed out.

[0045] If the rocker arm, which is deflected for valve actuation, is pressed against the gas exchange valve with the extended piston 9 for valve stroke transmission, the hydraulic fluid pressure in the pressure chamber 10 increases abruptly, the valve ball 21 closes the valve opening 20 to the hydraulic fluid reservoir 13, as a result of which the hydraulic fluid can only flow out via a defined leakage gap formed between the piston 9 and the end section 8 of the adjusting screw 2, so that the piston 9 is held rigidly by the hydraulic pressure cushion enclosed in the pressure chamber 10 and a valve stroke can be transmitted from the rocker arm via the piston 9 to the gas exchange valve to be actuated. At the same time, any valve play present in the arrangement can be compensated for.

[0046] The proposed hydraulic unit 1 also enables a particularly simple adjustment of the piston 9 on the valve contact surface 18 in the contact position according to Fig. 1 maximum transferable valve stroke. For this purpose, a sleeve 23 is provided which is arranged coaxially to the free end section 8 of the adjusting screw 2 and the piston 9 which is movably guided thereon ( Fig. 1 and Fig. 2). Starting from the connection of the widened end section 8 to the shaft 3 of the adjusting screw 2, the sleeve 23 comprises the end section 8 and the piston 9 guided thereon with its free end, wherein the free end of the end section 8 and the piston 9 guided thereon with the valve contact surface 18 protrude from the free axial end of the sleeve 23.

[0047] The sleeve 23, with its axial end facing the shaft 3, is connected radially to the outer diameter of the shaft 3 by a cup-shaped, radially inwardly extending annular collar 24 and axially to the free end face of the end section 5 facing the latter. For fastening, the sleeve 23 can be screwed, caulked, or welded to the adjusting screw 2, for example.

[0048] The sleeve 23 is arranged with its inner diameter and thus its inner circumference radially spaced from the outer diameter and thus from the outer circumference of the piston 9, which is movably mounted and guided on the end section 8. Thus, the sleeve 23 and the piston 9 radially delimit an annular space in which the return spring means 22 are arranged coaxially between the piston 9 and the sleeve 23.

[0049] The relative movement of the piston 9 relative to the sleeve 23 is limited by stop means in the contact position of the piston 9. For this purpose, a second sleeve 25 is preferably coaxially attached to the free end of the sleeve 23, with its inner diameter matching the outer diameter of the first sleeve 23. The latter is designed with a radially inwardly extending annular collar 26 that axially delimits the annular space. The sleeves 23, 25 are preferably each made of sheet metal.

[0050] A stop ring 27 is provided on the piston 9, which is fixed in a groove 28 on the outer diameter of the piston 9 and is arranged protruding therefrom in such a way that it can be applied to the sleeve 23, movable relative to the latter with the piston 9, to limit the relative movement of the piston 9 with respect to the sleeve 23, on the collar 26 formed on the second sleeve 25 as a stop in the contact position of the piston 9 for transmitting a maximum valve stroke.

[0051] The collar 26 formed on the second sleeve 25 also serves as a spring support for the return spring means 22. These are supported with one spring end on this collar 26 and with the other spring end on a collar 30 formed radially projecting on the outer diameter of the free end of the piston 9.

[0052] Consequently, by screwing the adjusting screw 2 into the threaded bore 6, the sleeve 23 fastened to the adjusting screw 2 and the second sleeve 25 fastened to the latter with the collar 26 and thus the stop position in the contact position of the piston 9 relative to the valve-side lever arm 7 can be moved axially with the adjusting screw 2 and thus the maximum valve stroke that can be transmitted on the piston 9 at the valve contact surface 18 can be adjusted as desired.

[0053] At the same time, the piston 9 is secured against falling out by the return spring means 22, the stop ring 27 and the second sleeve 25 with the collar 26.

[0054] To limit the relative movement of the piston 9 relative to the adjusting screw 2 in the contact-free home position, the piston 9 can be placed with the collar 30 flush against the collar 24 formed on the first sleeve 23 as a stop in the home position. In this way, the piston stroke H in the contact position relative to the home position of the piston 2 can be precisely adjusted by the stops 24, 26. At the same time, the stop position of the piston 9 can be shifted both in the contact position and in the contact-free home position with the adjusting screw 2 when screwing in.

[0055] For venting and passage of hydraulic fluid, several axial passage openings 34 distributed over the circumference are provided on the collar 24 ( Fig. 1 to 3).

[0056] Fig. 3 shows a perspective view of the hydraulic assembly 1. This is connected to the external thread 4 of the shaft 3 of the adjusting screw 2 in a threaded hole 6 at the end of the valve-side lever arm 7 of the Fig. 4 shown standardized rocker arm. The adjusting screw 2 is designed on one axial end face with a contour 31, here in the form of a hexagon socket, for the positive engagement of a screwing tool ( Fig. 1 to 3, 5 and 6), with which it can be screwed into the threaded hole 6 on the rocker arm.

[0057] Fig. 5 and Fig. 6 show the rocker arm Fig. 4 with the hydraulic assembly 1 screwed into the threaded bore 6. The rocker arm is preferably designed as a standardized forged component for use in a heavy-duty or medium-duty internal combustion engine.

[0058] The hydraulic assembly 1 is arranged in the threaded bore 6 for valve lift transmission, directly in the power flow between the valve-side lever arm 7 and a gas exchange valve (not shown) of the internal combustion engine to be actuated. It is screwed into the threaded bore 6 with the adjusting screw 2 and the shaft 3 on the underside of the lever, so that the piston 9 with the valve contact surface 18 for valve lift transmission protrudes on the underside of the lever, and the adjusting screw 2 is fastened to the valve-side lever arm 7 on the upper side of the lever with the lock nut screwed onto the upper end of the shaft 3. By screwing the adjusting screw 2 into the threaded bore 6, the maximum valve lift that can be transmitted at the rocker arm on the hydraulic assembly 1 can be adjusted.

[0059] The rocker arm is driven on a drive-side lever arm 32 by a camshaft (not shown) directly via a pickup means (not shown), for example a cam roller, or indirectly via a pushrod with a cam lift movement for valve actuation. It is arranged on a rocker arm axis (not shown) so that it can be pivoted about this axis with the lever arms 7, 32. For this purpose, a receiving opening 33 for the passage of the rocker arm axis is provided in a central region of the rocker arm located between the lever arms 7, 32. An oil supply bore (not shown) is formed on the inner diameter of the receiving opening 35, via which the rocker arm, in particular the hydraulic fluid connection 14 on the valve-side rocker arm 7, can be supplied with hydraulic fluid via the rocker arm axis. Oil from the engine oil circuit is preferably used as the hydraulic fluid.

[0060] Fig. Figure 1 shows the rocker arm with the activated hydraulic assembly 1. Piston 9 is pressurized with hydraulic fluid and extended into the contact position with the full piston stroke H, opposite the contact-free basic position. The contact-free basic position and the contact position are each indicated by a dashed line.

[0061] In this case, it is in direct or indirect contact with the valve contact surface 18 for valve lift transmission via a transmission element with at least one gas exchange valve (not shown) to be actuated. By screwing the adjusting screw 2 into the threaded bore 6, any predetermined maximum valve lift that can be transmitted to the hydraulic unit 1 and thus to the rocker arm can be set.

[0062] In Fig. 2 and Fig.6, the hydraulic assembly 1 is deactivated. For this purpose, the hydraulic fluid supply to the piston 9 is interrupted. The piston 9 is returned from the contact position to the contact-free home position by the spring force of the return spring means 22 and retracted into the threaded bore 6. The contact-free home position and the contact position are each indicated by a dashed line.

[0063] As a result, in the cam base circle phase of the driving cam, the piston 9 with the valve contact surface 18 is arranged at a distance of the length of the piston stroke H from the gas exchange valve (not shown) or from a transmission element arranged for valve stroke transmission.

[0064] If the rocker arm is again in the cam lift phase in a pivoted position with the hydraulic unit 1 deactivated and the piston 9 returned to the contact-free basic position, the rocker arm is arranged with the valve contact surface 18 at maximum deflection or pivoting of the valve-side lever arm 7, spaced by an air gap with a distance length S from the gas exchange valve or a transmission element arranged for valve lift transmission. As a result, the rocker arm performs an idle stroke, so that no valve lift can be transmitted to the hydraulic unit 1 and thus to the rocker arm, and valve lift deactivation is achieved.

[0065] The size of the air gap or the distance length S is adjustable by the piston stroke H and is preferably selected so that, under the specific operating and usage conditions of the internal combustion engine, operational disturbances, in particular due to thermal length changes of the components during operation, especially during engine braking, a collision of an open gas exchange valve with the working piston of the internal combustion engine, are reliably avoided. List of reference symbols 1 hydraulic unit 2 adjusting screws 3 shaft 4 external threads 5 internal threads 6 threaded hole 7 valve-side lever arm 8 Final section 9 pistons 10 Printing room 11 Central axis 12 Check valve 13 Hydraulic fluid storage room 14 Hydraulic fluid connection 15 Recording room 16 deployment 17 printing area 18 Valve contact surface 19 Valve spring means 20 valve opening 21 Valve ball 22 Return spring means 23 first sleeve 24 Collar, stop in the basic position 25 second sleeve 26 Collar, stop in the contact position 27 Stop ring 28 grooves 29 Lock nut 30 collars 31 Contour 32 drive-side lever arm 33 Receiving opening 34 Passage opening H piston stroke S air gap, distance length QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2020 / 216474

[0002]

Claims

[1] Hydraulic unit (1) for arrangement in a rocker arm for a valve train of an internal combustion engine, characterized by that an adjusting screw (2) carrying hydraulic medium is provided for screwing into a threaded bore (6) on the rocker arm, wherein a piston (9) which can be acted upon by hydraulic medium from this and has a valve contact surface (18) for valve stroke transmission is movably attached to the adjusting screw (2), in such a way that the piston (9) can be reset in a hydraulically pressure-free state from a contact position for valve stroke transmission into a contact-free basic position for valve stroke shutdown, and by screwing in the adjusting screw (2) the maximum valve stroke which can be transmitted on the rocker arm in the contact position of the piston (9) can be adjusted. [2] Hydraulic assembly (1) according to claim 1, characterized bythat a check valve (12) is provided for hydraulically controlling the piston (9) and the piston (9) can be acted upon via the check valve (12) with hydraulic medium for valve stroke transmission in the contact position, wherein the hydraulic medium can be returned via the check valve (12) in the hydraulically pressure-free state of the piston (9) for returning the piston to the contact-free basic position. [3] Hydraulic assembly (1) according to claim 2, characterized by that the check valve (12) is preloaded into the open state by valve spring means (19). [4] Hydraulic assembly (1) according to one of claims 1 to 3, characterized byin that the piston (9) is at least partially coaxially surrounded by a sleeve (23) fastened to the adjusting screw (2) and is arranged to be movable relative to the latter, the relative movement of the piston (9) with respect to the adjusting screw (2) in the contact position of the piston (9) being limited by stop means (26, 27) in the sleeve (23) in such a way that the stop position can be moved by screwing in the adjusting screw (2) and the maximum valve stroke that can be transmitted on the piston (9) can be adjusted. [5] Hydraulic assembly (1) according to claim 4, characterized by that the relative movement of the piston (9) relative to the adjusting screw (2) in the sleeve (23) is limited by a further stop (24) in the contact-free basic position of the piston (2). [6] Hydraulic assembly (1) according to one of claims 4 or 5, characterized bythat the stop means comprise a stop ring (27) which is fixed in a groove (28) on the outer diameter of the piston (9) and is arranged protruding therefrom in such a way that it is movable with the piston (9) relative to the sleeve (23) and can be applied to a stop (26) formed on the sleeve (23) in the contact position of the piston (9) in order to limit the relative movement. [7] Hydraulic assembly (1) according to claim 6, characterized by that the stop (26) is formed by a second sleeve (25) attached to the free end of the sleeve (23). [8] Hydraulic assembly (1) according to one of claims 1 to 7, characterized by that the piston (9) cooperates with return spring means (22) to return to the contact-free basic position. [9] Hydraulic assembly (1) according to claim 8, characterized by that the return spring means (22) are arranged as a helical compression spring in the sleeve (23) acting coaxially between the latter and the piston (9). [10] Rocker arm for a valve train of an internal combustion engine, with at least one hydraulic unit (1) according to one of claims 1 to 9.

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