Switchable rocker arm for a valve train of an internal combustion engine

Abstract

The invention relates to a switchable rocker arm for a valve train of an internal combustion engine, characterized in that a switchable check valve (5) is provided for the hydraulic control of at least one valve lift transmission element (2) which can be controlled for valve lift transmission and deactivation, which is arranged displaceably with a sliding body (6) in a receiving bore (7) communicating with a hydraulic medium connection (3, 4) for switching by an actuator

Description

The invention relates to a switchable rocker arm for a valve drive of an internal combustion engine.WO 2020 / 216474 discloses a rocker arm with a hydraulic capsule having a hollow capsule body which comprises a hydraulic connection for fluid connection and a tappet and a locking set, the latter being switchable between a locked state and an unlocked state. An insert is provided for adjusting the latch, the plunger configured to urge the latch set toward the insert for adjusting the latch.The object of the invention is therefore to propose a rocker lever of the aforementioned type, in which the hydraulic control for shifting is simplified in a structurally simple manner and the shifting times are shortened.The object is achieved by the features of claim 1. Further advantageous and claimed embodiments are evident from the respective dependent claims, the description and the drawings.Thus, a switchable rocker arm for a valve drive of an internal combustion engine is proposed, wherein for the hydraulic actuation of at least one valve lift transmission element that can be actuated for valve lift transmission and valve lift deactivation, a switchable check valve is integrated into the rocker arm, which is arranged with a sliding body so as to be displaceable in a receiving bore communicating with a hydraulic medium connection for switching by an actuator.Since the hydraulic control for switching the rocker lever takes place via the switchable nonreturn valve, additional hydraulic control valves are avoided. Consequently, the switchable rocker lever for supplying hydraulic medium can be directly acted upon by the hydraulic medium pressure provided by the internal combustion engine. As a result, the hydraulic medium pressure made available from the hydraulic medium supply of the internal combustion engine is directly present at the hydraulic medium connection in the rocker lever. In this way, losses due to the hydraulic loading of additional hydraulic components, in particular additional control valves, are avoided during the shifting, whereby the shifting times can be shortened.The hydraulic structural unit proposed can be used particularly advantageously in valve drives for heavy- and medium-load internal combustion engines, in particular for trucks, construction vehicles or construction machines, transporters, agricultural working equipment, in particular tractors, shipbuilding and mining equipment. In this case, it can be integrated in a further particularly advantageous manner in cast or forged, in particular standardized, rocker levers in a space-saving and weight-saving manner with little production and assembly effort and at low cost.In a preferred embodiment of the invention, by displacing the sliding body into an activating control position, the valve lift transmission element can be loaded with hydraulic medium for valve lift transmission via the check valve. By restoring the sliding body into a deactivating basic position, the hydraulic medium loading of the valve lift transmission element can be deactivated and the hydraulic medium can be discharged from the latter into the environment via the nonreturn valve.In this way, in particular a hydraulically switchable decompression engine brake can be realized in a simple manner. In addition, by hydraulic actuation, early opening of one or more exhaust valves of the internal combustion engine is possible, in particular for heating an exhaust gas catalytic converter. It is also conceivable to close one or more intake valves of the internal combustion engine late in order to increase the efficiency of the internal combustion engine.It is furthermore advantageous if the hydraulic medium connection comprises a hydraulic medium supply channel, which can be acted upon by hydraulic medium and opens out into the receiving bore with an outlet-side end, and a hydraulic medium connection channel, which opens out from the receiving bore with an inlet-side end and communicates with the valve stroke transmission element, wherein the respective ends of the aforementioned channels are arranged offset with respect to one another in the displacement direction of the sliding body.A simple embodiment of the check valve can be achieved in that a hydraulic medium passage channel is preferably formed in the sliding body for the hydraulic medium application to the valve lift transmission element. Preferably, a blocking body arranged in the hydraulic medium passage channel in a valve seat is provided for hydraulically tightly blocking the hydraulic medium passage channel in the blocking direction. In this way, in the activating control position, by applying hydraulic medium via the check valve, a hydraulic pressure cushion for transmitting force to the valve stroke transmission element for valve actuation of one or more gas exchange valves can be generated.Preferably, the hydraulic medium passage channel forms an inwardly offset valve seat on the inner circumference, in which the blocking body is arranged as a valve ball. Preferably, the blocking body is prestressed for blocking by valve spring means arranged in the hydraulic medium passage channel into the valve seat in a sealing manner.Preferably, the valve spring means are arranged with one spring end on the blocking body and with the other spring end on the inner wall of the receiving bore. When the sliding body is displaced, the valve spring means can thus slide with a spring end supported on the inner wall of the receiving bore.In a next development of the invention, for evacuation of the hydraulic medium from the valve stroke transmission element via the check valve during a valve stroke deactivation, an evacuation channel formed in the sliding body is provided, via which the hydraulic medium can be discharged from the valve stroke transmission element into a free space in the receiving bore communicating with the environment.Such an evacuation channel can be realized in a simple manner in that, starting from one end of the sliding body in the displacement direction, a first blind bore is provided, into which a second blind bore, starting from the outer periphery of the sliding body, runs transversely to the first blind bore opens.The switchable nonreturn valve makes it possible to achieve simple actuation of the valve stroke transmission element for the application of hydraulic medium by virtue of the fact that, in the activating control position of the sliding body, the hydraulic medium passage channel has its inlet-side end aligned opposite the outlet-side end of the hydraulic medium supply channel and its outlet-side end aligned opposite the inlet-side end of the hydraulic medium connection channel in flow communication.In a further particularly preferred embodiment of the invention, the hydraulic medium passage channel is designed as a through bore running perpendicular to the displacement axis of the sliding body. Preferably, a radial depression extending from the edge of the receiving bore in the displacement direction to the sliding body is provided at the outlet-side end of the hydraulic medium passage channel on the outer periphery of the sliding body, so that the outlet-side end of the hydraulic medium passage channel, in the activating control position of the sliding body, comes into flow connection via the depression with the inlet-side end of the hydraulic medium connection channel.Furthermore, a simple deactivation of the hydraulic medium loading of the valve lift transmission element via the check valve can preferably be achieved by the fact that, in the deactivating basic position of the sliding body, the hydraulic medium passage channel is covered with the inlet-side end and the outlet-side end on the inner wall of the receiving bore. At the same time, the evacuation channel with the inlet-side end aligned opposite comes into flow connection with the end of the hydraulic medium connection channel in the receiving bore, so that the hydraulic medium can be discharged from the valve stroke transmission element via the evacuation channel into the environment.It is furthermore advantageous if the sliding body cooperates with restoring spring means for restoring from the activating control position into the deactivating basic position, which restoring spring means are preferably arranged in the receiving bore in a manner saving installation space.Within the scope of a further preferred embodiment of the invention, the valve stroke transmission element has a piston with a valve contact surface, which is movably guided on a housing guiding hydraulic medium and from this piston can be acted upon with hydraulic medium for valve stroke transmission. Preferably, the piston can be reset from a contact position for valve lift transmission into a contact-free basic position for valve lift deactivation.It is particularly advantageous if the valve stroke transmission element preferably has an adjusting screw which is screwed into a threaded bore on the rocker arm with a free end section projecting therefrom, and the piston is supported coaxially at least partially surrounding the free end section by restoring spring means on the free end section, so that the maximum valve stroke which can be transmitted in the contact position of the piston on the rocker arm can be adjusted by screwing in the adjusting screw.The proposed rocker arm can be actuated individually for switching by the integrated switchable nonreturn valve via an actuator which is of mechanical, electro-mechanical, pneumatic or hydraulic design. It is also conceivable to actuate a plurality of such rocker levers individually or combined in groups, e.g. two or three or six rocker levers, simultaneously via a corresponding actuating device. In this way, in particular, an engine brake of any stepped configuration adapted to the respective operating conditions can be realized.Further claimed features of the invention will become apparent from the following description and from the drawings, on the basis of which the present invention is explained further. The following are shown: FIG. 1 shows a sectional partial plan view of a switchable rocker arm according to the invention in a first operating state, FIG. 2 shows a sectional partial plan view of a switchable rocker arm according to the invention in a second operating state, FIG. 3 shows a cross section of the switchable nonreturn valve with the sliding body in a single view, FIG. 4 shows a perspective individual view of the switchable nonreturn valve, FIG. 5 shows a plan view of the switchable nonreturn valve from FIG. 4, FIG. 6 shows a sectional view of the switchable nonreturn valve from FIG. 5, FIGS. 7 and 8 show the rocker lever in different perspective side views, FIG. 9 is a side view of the rocker arm in the first operating state, FIG. 10 shows a sectional top view of the rocker arm from FIG. 9, FIG. 11 is a front perspective view of the rocker arm of FIG. 9, FIG. 12 is a sectional side view of the rocker arm of FIG. 11, FIG. 13 shows an enlarged detail from FIG. 12, FIG. 14 is a side view of the rocker arm in the second operating state, FIG. 15 shows a sectional top view of the rocker lever from FIG. 9, an enlarged detail from FIG. 14, FIG. 16 is a front perspective view of the rocker arm of FIG. 14, FIG. 17 is a sectional side view of the rocker arm of FIG. 16, FIG. 18 shows an enlarged detail from FIG. 17.Various views and embodiments of a switchable rocker arm according to the invention are illustrated by way of example in the figures.FIGS. 1 and 2 each show an enlarged detail of the valve-side lever arm 1 of the rocker lever. A hydraulic valve stroke transmission element 2 is arranged at the end of the valve-side lever arm 1 for valve stroke transmission in the force flow between the latter and at least one gas exchange valve, not shown, of the internal combustion engine. The valve stroke transmission element 2 can be hydraulically activated via a hydraulic medium connection 3, 4 formed in the rocker arm with a switchable nonreturn valve 5 for valve stroke transmission and deactivation.For hydraulic actuation of the valve lift transmission element 2, the switchable nonreturn valve 5 is integrated into the valve-side lever arm 1. The check valve 5 is arranged with a sliding body 6 in a receiving bore 7 communicating with the hydraulic medium connection 3, 4 so as to be displaceably guided along a displacement axis 8 for switching. The receiving bore 7 extends perpendicular to the lever longitudinal axis 9 between the lever longitudinal sides of the valve-side lever arm 1 and is designed to be open at its axial ends.By displacing the sliding body 6 into an activating control position according to FIG. 1, the valve lift transmission element 2 can be acted upon with hydraulic medium via the check valve 5 for valve lift transmission at the rocker arm. By restoring the sliding body 6 into a deactivating basic position according to FIG. 2, the hydraulic medium loading of the valve stroke transmission element 2 can be deactivated by the check valve for valve stroke deactivation. At the same time, the hydraulic medium can be discharged from the valve stroke transmission element 2 via the nonreturn valve 5 into the environment.The check valve 5 is designed according to FIGS. 3 to 6 with a cylindrical sliding body 6, which has a flattened portion 11 on its upper side over its entire axial length (FIGS. 3 and 4 ). Corresponding to this on the sliding body 6, the receiving bore 7 is formed on its upper inner side with a corresponding flattened portion, so that the sliding body 6 with the flattened portion 11 on the flattened portion is guided displaceably in the bore 7 in a manner secured against rotation.The sliding body 6 protrudes from the receiving bore 7 with a flat engagement surface formed at its actuation-side axial end 13 (FIGS. 1 and 2 ). The planar axial engagement surface 13 serves for engaging an actuator, not shown, for transmitting an axial displacement force, as indicated by an arrow, for displacing and switching the nonreturn valve 5 in the receiving bore 7. At the axial end 26 open to the environment, which is remote from the actuation-side end, the receiving bore 7 is embodied in a receiving housing 10 which projects on the longitudinal side of the valve-side lever arm 1 and is formed integrally with the valve-side lever arm 1.The receiving bore 7 forms, in the region of its end on the side of its actuation, an end stop 14, on which the sliding body 6 is limited in its displacement movement in the basic position according to FIG. 2. For this purpose, the receiving bore 7 is retracted on the inner diameter at the end stop 14 by means of an annular shoulder, on which the sliding body 6 can be placed in the base position in the region of its actuating-side end 13 by means of a corresponding stop surface 32. For this purpose, the sliding body 6 is offset on the outer circumference by a retraction (FIGS. 1 to 4 and 6 ).For resetting, the check valve 5 interacts at the axial end of the sliding body 6 remote from the actuation-side axial end 13 with resetting spring means 15 which are arranged in a free space 16 of the receiving bore 7 and prestress the sliding body 6 for resetting. The restoring spring means 15 are arranged coaxially in the receiving bore 7 as a helical compression spring and are supported with one spring end on the flat spring support surface formed on the facing end face 17 of the sliding body 6. With the other spring end, they are supported on a securing ring 18 arranged radially protruding in the free space 16 in a groove on the inner diameter of the cylindrical end section of the receiving bore 7.For the application of hydraulic medium to the valve stroke transmission element 2, the check valve 5 comprises a hydraulic medium passage channel 19 which is formed in the sliding body 6 and is designed as a through bore (FIGS. 1 to 6 ). The hydraulic medium passage channel 19 runs perpendicular to the displacement axis 8 in the lever longitudinal direction with the inlet-side and outlet-side ends 20, 21 located on the cylindrical outer periphery of the displacement body 6. The outlet-side end 21 is widened, with a radial depression 45 which originates at the outer periphery of the sliding body 6 from the edge of the receiving bore 7, is open toward the inner wall of the receiving bore 7 and extends in the direction of the displacement axis 8 toward the axial spring-support-side end 17.In a valve seat 22 which is offset at the inner diameter in the hydraulic medium passage channel 19 at the inlet, a blocking body 23 for hydraulically tightly blocking the hydraulic medium passage channel 19 is arranged (FIGS. 1, 2 and 6 ). The blocking body 23 is designed as a valve ball and is prestressed in the blocking direction by valve spring means 24 into the valve seat 22. The valve spring means 24 are arranged coaxially as a helical compression spring in the hydraulic medium passage channel 19. They are supported with one spring end on the blocking body 23 and with the other spring end on the open end 21 of the hydraulic medium passage channel 19 on the inner wall of the receiving bore 7 (FIGS. 1 and 2 ). When the sliding body 6 is displaced, the valve spring means 24 are thus supported with one spring end slidingly on the inner wall of the receiving bore 7.The check valve 5 has an evacuation channel 25 formed in the sliding body 6, via which the hydraulic medium for valve lift deactivation can be discharged from the valve lift transmission element 2 into the free space 16 in the receiving bore 7 and via the open end 26 of the receiving bore 7 on the receiving housing 10 into the environment.The evacuation channel 25 is formed by two blind holes 27, 28 running perpendicular to one another. A first blind bore 27 extends in the direction of the displacement axis 8, into which a second blind bore 28, which extends perpendicularly to the first blind bore 27 starting from the outer periphery of the sliding body 6 opens (FIGS. 1, 2 and 6 ).The hydraulic medium connection 3, 4 to the valve stroke transmission element 2 comprises a hydraulic medium supply channel 3, which communicates with a hydraulic medium reservoir, not shown, of the internal combustion engine and opens with an outlet-side end 29 into the receiving bore 7. The hydraulic medium connection 3, 4 furthermore comprises a hydraulic medium connection channel 4 which, with one end 30, originates from the receiving bore 7 and connects the valve stroke transmission element 2 to the receiving bore 7. The hydraulic medium supply channel 3 and the hydraulic medium connection channel 4 extend in the direction of the lever longitudinal axis 9 in parallel offset relationship to one another.The hydraulic medium system pressure provided by the reservoir of the internal combustion engine prevails in the hydraulic medium supply channel 3. In this way, the hydraulic medium system pressure of the internal combustion engine is permanently applied directly to the rocker arm and to the check valve 5 integrated therein.By displacing the sliding body 6 from a deactivating basic position according to FIG. 2 into an activating control position shown in FIG. 1, as indicated by an arrow, the check valve 5 with the inlet-side end 20 of the hydraulic medium passage channel 19 in flow connection comes in flush alignment with the outlet-side end 29 of the hydraulic medium supply channel 3. At the same time, it is positioned on the outlet-side end 21 of the hydraulic medium passage channel 19 with the depression 45 in alignment opposite the end 30 of the hydraulic medium connection channel 4 in flow connection.As a result, the hydraulic medium passage channel 19 is charged with hydraulic medium from the hydraulic medium supply channel 3 and the spring-loaded blocking body 23 is pressed out of the valve seat 22 into the open state. At the same time, the valve stroke transmission element 2 communicating with the latter is actuated with hydraulic medium via the depression 45 at the outlet-side end 21 of the hydraulic medium passage duct 19 of the hydraulic medium connection duct 4 for valve stroke transmission via the nonreturn valve 5. At the same time, by displacing the sliding body 6 into the activating control position, the restoring spring means 15 interacting with the latter are prestressed for restoring the sliding body 6 into the basic position.By restoring or displacing the sliding body 6 back by the spring force of the prestressed restoring spring means 15 from the activating control position into the deactivating basic position illustrated in FIG. 2, the nonreturn valve 5 with the inlet-side and outlet-side ends 20, 21 of the hydraulic medium passage duct 19 comes out of flow connection with the hydraulic medium supply duct 3 and the hydraulic medium connection duct. The outlet end 29 of the hydraulic medium supply channel 3 is covered by the sliding body 6, and the inlet and outlet ends 20, 21 of the hydraulic medium passage channel 19 are covered by the inner wall of the receiving bore 7. Accordingly, the hydraulic fluid supply to the valve lift transmitting member 2 is cut off by the check valve 5. In addition, the spring-biased blocking body 23 of the check valve 5 is pressed into the valve seat 22 and the hydraulic medium passage channel 19 is blocked.At the same time, in the deactivating basic position of the sliding body 6, the end 30 of the hydraulic medium connection channel 4 comes opposite the inlet-side end 33 of the blind bore 28 of the evacuation channel 25 in alignment and is in flow connection therewith. Consequently, the hydraulic medium can be conducted out of the valve stroke transmission element 2 via the check valve 5 into the free space 16 in the receiving bore 7 and out of the latter via the open end 26 on the receiving housing 10 into the environment.FIGS. 7 and 8 show the proposed rocker arm with the switchable nonreturn valve 5 integrated into the valve-side lever arm 1 and the hydraulically actuatable valve stroke transmission element 2 arranged at the end of the valve-side lever arm 1. It protrudes perpendicularly with the axial engagement surface 13 formed at the actuation-side end of the sliding body 6 out of the receiving bore 7 for actuation by an actuator, not shown (FIG. 8 ). On the opposite longitudinal side of the valve-side lever arm 1, the receiving housing 10 protrudes perpendicularly with the open end 26 of the receiving bore 7.The rocker arm is preferably produced by casting as a cast component and is provided for use in a heavy-duty and medium-duty internal combustion engine. An embodiment as a forged component is also conceivable. The rocker arm can be driven on a drive-side lever arm 33 by a camshaft, not shown, directly via pick-off means, not shown, for example a cam roller, or indirectly via a pushrod with a cam lifting movement for valve actuation. It can be arranged on a not shown rocker lever axle so as to be pivotable about the latter with the lever arms 1, 33. For this purpose, a receiving opening 34 is provided in a central region of the rocker arm situated between the lever arms 1, 33 for the passage of the rocker arm axis. An oil supply bore 35 is formed on the inner diameter of the receiving opening 34, via which the rocker arm, in particular the hydraulic medium connection 3, 4 on the valve-side lever arm 1, can be supplied with hydraulic medium via the rocker arm axis. Oil from the engine oil circuit is preferably used as hydraulic medium.FIGS. 9 to 13 show the rocker arm with the activated hydraulically actuatable valve stroke transmission element 2; according to FIG. 13, the valve stroke transmission element 2 comprises a hollow cylindrical housing 36 arranged at the end of the valve-side lever arm 1 on the lever underside facing the valve, which housing is configured integrally with the valve-side lever arm 1 and open on one side toward the lever underside.At the open end of the housing 36, a hollow cylindrical piston 37, open on one side, is inserted with its open end with the outer diameter at the inner diameter of the housing 36 and is arranged movably guided on the latter. The piston 37 and the housing 36 delimit a pressure chamber 38; the latter and the piston 37 can be acted upon with hydraulic medium via the hydraulic medium connection channel 4 indicated guided through on the housing 36.An adjusting screw 39 is screwed into a threaded bore 40 on the valve-side lever arm 1 with a free end section 41 on the lever underside facing the valve, projecting into the pressure chamber 38. On the lever top side facing away from the valve, the adjusting screw 39 is fastened by a lock nut 42. At the upper end of the adjusting screw situated on the lever top side, a contour 46 for positively engaging a screwing tool, for example an internal hexagon for engaging a screwing tool, is provided on the end side.The piston 37 comprises the free end portion 41 coaxially and is supported relatively movably therewith by return spring means 43. The restoring spring means 43 are preferably designed as a helical compression spring and are arranged coaxially in the piston 37 so as to act between the latter and the free end section 41 of the adjusting screw 39.The piston 37 forms on its outer end face a valve contact surface 44, with which it is in contact with at least one gas exchange valve, not shown, in the illustrated contact position for valve lift transmission. A valve lift transmission at the valve contact surface 39 via a transmission element, for example a valve bridge, is also conceivable.The piston 37 is guided movably on the housing 36 in a hydraulically actuatable manner via the hydraulic medium connection channel 4 and the pressure chamber 38. From the contact position for valve lift transmission shown, it can be reset into a contact-free basic position for valve lift deactivation shown in FIG. 18, via which the restoring spring means 43 can be reset.In FIGS. 9 to 13, the check valve 5 is switched into the activating position. The pressure chamber 38 and the piston 37 are charged with hydraulic medium via the hydraulic medium connection 3, 4 in the rocker arm and via the check valve 5. If the piston 37 is free of load, it is forced out into the contact position for valve lift transmission according to FIG. 13. As a result, it is extended into the contact position with the full piston stroke H relative to the contact-free basic position into the contact position (FIG. 13 ). The contact-free basic position and the contact position are each indicated by a dashed line in FIG. 13.In this case, the piston 37 is in direct or indirect contact with the valve contact surface 44 with at least one gas exchange valve, not shown, to be actuated for valve lift transmission. If the rocker lever deflected for valve actuation is pressed with the extended piston 37 against the gas exchange valve for valve lift transmission, the hydraulic medium pressure in the pressure chamber 38 rises abruptly, the blocking body 21 closes the check valve 5, as a result of which the piston 37 is held rigidly by the hydraulic pressure cushion enclosed in the pressure chamber 38 and a valve lift can be transmitted from the rocker lever via the piston 37 to the gas exchange valve to be actuated.In this case, by screwing the adjusting screw 39 into the threaded bore 40, an arbitrarily predetermined valve stroke which can be transmitted at the piston 37 of the valve stroke transmission element 1 and thus the maximum valve stroke which can be transmitted at the rocker lever can be adjusted.FIGS. 14 to 18 show the rocker arm with the deactivated hydraulically actuatable valve lift transmission element 2. As a result, the hydraulic medium loading of the piston 37 is switched off. The piston 37 is reset from the contact position into the contact-free basic position by the spring force of the restoring spring means 43 and is retracted into the housing 36. In this case, the hydraulic medium is led out of the pressure chamber 38 by the piston 37 via the hydraulic medium connection channel 4 and the evacuation channel 25 which communicates with the check valve 5 in the deactivating basic position thereof into the environment. The contact-free basic position and the contact position are each again indicated by a dashed line in FIG. 18.If the rocker arm is again in the cam stroke phase in the pivoted position with the valve stroke transmission element 2 deactivated and the piston 37 reset into the non-contact base position, the latter is arranged with the valve contact surface 44 at a distance from the gas exchange valve by an air gap with a distance S when the valve-side lever arm 1 is deflected or pivoted to the maximum extent. As a result, the rocker arm executes an idle stroke, so that no valve lift can be transmitted to the valve lift transmission element 2 and thus to the rocker arm, and a valve lift deactivation is achieved.The size of the air gap or the spacing length S can be adjusted in particular by the piston stroke H and is preferably selected such that operating disturbances in the specific operating and operating conditions of the internal combustion engine, in particular due to thermal changes in length of the components during operation, in particular in engine braking operation a collision of an open gas exchange valve with the working piston of the internal combustion engine, are reliably avoided.List of reference characters1 Valve-side lever arm 2 Valve stroke transmission element 3 Hydraulic medium connection, hydraulic medium supply channel 4 Hydraulic medium connection, hydraulic medium connection channel 5 Check valve 6 Sliding body 7 Receiving bore 8 Displacement axis 9 Lever longitudinal axis 10 Receiving housing 11 Flattened portion 13 Actuation-side end of the sliding body, engagement surface 14 End stop 15 Restoring spring means, helical compression spring 16 Free space 17 End of the sliding body, spring support surface 18 Securing ring 19 Hydraulic medium passage channel 20 Inlet-side end of the hydraulic medium passage channel 21 Outlet-side end of the hydraulic medium passage channel 22 Valve seat 23 Blocking body, valve ball 24 Valve spring means, Helical compression spring 25 Evacuation channel 26 Axial end of the receiving bore 27 First blind bore 28 Second blind bore 29 Outlet-side end of the hydraulic medium supply channel 30 End of the hydraulic medium connection channel 32 Stop surface 33 Drive-side lever arm 34 Receiving opening 35 Oil supply bore 36 Housing 37 Piston 38 Pressure chamber 39 Adjusting screw 40 Threaded bore 41 End section 42 Counter nut 43 Restoring spring means 44 Valve contact surface 45 Depression 46 Contour at the adjusting screw H Piston stroke S Air gap, distance lengthReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedWO 2020 / 216474

[0002]

Claims

Switchable rocker arm for a valve drive of an internal combustion engine, characterized in that a switchable nonreturn valve (5) is provided for hydraulically actuating at least one valve lift transmission element (2) which can be actuated for valve lift transmission and valve lift deactivation, said nonreturn valve being arranged displaceably with a sliding body (6) in a receiving bore (7) which communicates with a hydraulic medium connection (3, 4) for switching by an actuator.Switchable rocker arm according to Claim 1, characterized in that, by displacing the sliding body (6) into an activating control position, the valve stroke transmission element (2) can be acted upon with hydraulic medium via the nonreturn valve (5) for valve stroke transmission, and, by restoring the sliding body (6) into a deactivating basic position, the hydraulic medium action on the valve stroke transmission element (2) can be deactivated for valve stroke deactivation, and the hydraulic medium can be discharged from the latter into the environment via the nonreturn valve (5).Switchable rocker lever according to either of Claims 1 and 2, characterized in that the hydraulic medium connection comprises a hydraulic medium supply duct (3) which can be acted upon by hydraulic medium and opens out into the receiving bore (7) with an outlet-side end (29), and a hydraulic medium connection duct (4) which communicates with the valve stroke transmission element (2) with an end (30), starting from the receiving bore (7), the respective ends (20, 29) of the abovementioned ducts (3, 4) being arranged offset with respect to one another in the displacement direction of the sliding body (6).Switchable rocker lever according to one of Claims 1 to 3, characterized in that the nonreturn valve (5) for the application of hydraulic medium to the valve stroke transmission element (2) has a hydraulic medium passage channel (19) which is formed in the sliding body (6) and a blocking body (23) which is arranged in the latter in a valve seat (22) and is spring-loaded in the blocking direction for hydraulically sealing off the hydraulic medium passage channel (19).Switchable rocker arm according to one of Claims 1 to 4, characterized in that the nonreturn valve (5) has an evacuation channel (25) which is formed in the sliding body (6) and via which the hydraulic medium for valve lift deactivation can be discharged from the valve lift transmission element (2) into a free space (16), open towards the environment, in the receiving bore (7).Switchable rocker lever according to either of Claims 4 and 5, characterized in that, in the activating control position of the sliding body (6) for the application of hydraulic medium to the valve stroke transmission element (2), the nonreturn valve (5) comes into flow connection with the inlet-side end (20) of the hydraulic medium passage duct (19), aligned opposite the outlet-side end (29) of the hydraulic medium supply duct (3), and with the outlet-side end (21) of the hydraulic medium passage duct (19), aligned opposite the inlet-side end (30) of the hydraulic medium connection duct (4).Switchable rocker lever according to one of Claims 4 to 6, characterized in that the hydraulic medium passage channel (19) is designed as a through bore running transversely with respect to the displacement axis (8) of the sliding body (6), wherein a radial depression (45), which originates from the edge of the receiving bore (7) and extends in the displacement direction to the sliding body (6), is provided on the outlet-side end (21) of the hydraulic medium passage channel (19) on the outer periphery of the sliding body (6) in such a way that, in the activating control position of the sliding body (6), said depression comes into flow connection with the end (30) of the hydraulic medium connection channel (4).Switchable rocker lever according to one of Claims 5 to 7, characterized in that, in the deactivating basic position of the sliding body (6) for switching off the hydraulic medium loading of the valve stroke transmission element (2), the nonreturn valve (5) is covered on the inner wall of the receiving bore (7) by the inlet-side and the outlet-side ends (21) of the hydraulic medium passage duct (19), and the evacuation duct (25) comes into flow connection with the inlet-side end (33), aligned opposite the end (30) of the hydraulic medium connection duct (4).Switchable rocker lever according to one of Claims 2 to 8, characterized in that the sliding body (6) interacts with restoring spring means (15), which are arranged in the receiving bore (7), for restoring from the activating control position into the deactivating basic position.Switchable rocker arm according to one of Claims 1 to 9, characterized in that the valve stroke transmission element (2) has a piston (37), which is guided movably on a housing (36) which conducts hydraulic medium and can be acted upon by hydraulic medium from the housing for valve stroke transmission and has a valve contact surface (44), which can be reset from a contact position for valve stroke transmission into a contact-free basic position for valve stroke deactivation.

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