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

Abstract

The invention relates to a hydraulic assembly (1) for arrangement in a rocker of a valve train of an internal combustion engine, characterized in that an adjusting screw (2) for guiding a hydraulic medium is provided for screwing into a threaded bore (6) on the rocker, a piston (9), into which a hydraulic medium is loaded and which has a valve contact surface (18), is movably connected to the adjusting screw (2) in order to transmit a valve lift, in such a way that the piston can be reset from a contact position for transmitting the valve lift to a contactless base position for closing the valve lift in the state of no hydraulic pressure, the maximum valve lift which can be transmitted on the rocker can be adjusted in the contact position of the piston (9) by screwing in the adjusting screw (2). The invention also relates to a rocker for a valve train of an internal combustion engine, comprising at least one such hydraulic assembly (1).

Description

Field of the Invention

[0001] The present invention relates to a hydraulic structural unit for being arranged in a rocker of a valve mechanism of an internal combustion engine. The present invention also relates to a rocker for a valve mechanism of an internal combustion engine, the rocker having at least one such hydraulic structural unit. Background Art

[0002] A hydraulic capsule having a hollow capsule body is known from WO 2020 / 216474. The capsule body includes a hydraulic port for fluid connection, a plunger, and a latch group, wherein the latter can be switched between a latched state and an unlocked state. An insert for adjusting the latch is provided, wherein the plunger is configured to push the latch group in the direction of the insert to adjust the latch. Summary of the Invention

[0003] The object of the present invention is to provide a hydraulic structural unit and a rocker of this type, which can achieve valve lift closing and adjustment of the maximum transmissible valve lift in a structurally simple and space-saving manner.

[0004] This object is achieved by the features of claim 1 and alternatively by the features of claim 10. Other advantageous and protected design solutions are derived from the corresponding dependent claims, the description, and the drawings.

[0005] Therefore, a hydraulic structural unit for being arranged in a rocker of a valve mechanism of an internal combustion engine is proposed. In order to achieve valve lift closing in a structurally simple and space-saving manner, an adjusting screw for guiding a hydraulic medium is provided, and the adjusting screw is used for screwing into a threaded hole on the rocker. Here, a piston having a valve contact surface and from which the hydraulic medium can be loaded is movably sleeved on the adjusting screw to transmit the valve lift, so that the piston can be reset from the contact position for transmitting the valve lift to a non-contact basic position for closing the valve lift in a state without hydraulic pressure. At the same time, by screwing the adjusting screw into the threaded hole on the rocker, the maximum transmissible valve lift on the rocker at the contact position of the piston can be adjusted.

[0006] In this way, the directly hydraulically controllable piston movable relative to the adjusting screw transmits the valve lift in the force flow between the rocker and at least one exchange valve of the internal combustion engine through direct contact with it on the valve contact surface. It is also conceivable to transmit the valve lift on the valve contact surface through indirect contact via a transmission element, such as via a valve bridge.

[0007] By resetting the piston to the non-contact basic position, the piston is disengaged from the exchange valve or the transmission element, so that the rocker can perform an idle stroke. Therefore, the closing of the valve lift can be achieved in the non-contact basic position of the piston.

[0008] The proposed hydraulic structural unit can particularly simply implement a hydraulically switchable decompression engine brake. In addition, it is possible to hydraulically control the early opening of one or more exhaust valves of an internal combustion engine in order to heat the exhaust gas catalyst, in particular. It is also conceivable to later close one or more intake valves of the internal combustion engine to increase the efficiency of the internal combustion engine.

[0009] Thus, a compactly constructed hydraulic structural unit for closing valve lift can be realized. The hydraulic structural unit, as a pre-assemblable structural unit, has its various components arranged along an axis and can be installed and fixed particularly simply and cost-effectively by screwing it into a threaded hole in the rocker arm, in particular a threaded hole in a standardized rocker arm, without the need for reworking. In addition, a complex switching mechanism with additional mechanical or hydraulic switching elements is avoided. Thereby, components can be reduced, the structure can be simplified, the moving mass can be reduced, and the valve train dynamics can be improved.

[0010] At the same time, by means of an adjusting screw that can be screwed into the threaded hole, it is possible to simply adjust the preset maximum valve lift that can be transmitted on the rocker arm.

[0011] The proposed hydraulic structural unit can be particularly advantageously applied in the valve train of internal combustion engines with heavy or medium loads, especially in the valve trains of goods vehicles, construction vehicles or construction machinery, transport vehicles, agricultural working equipment, especially tractors, ships and mining equipment. The hydraulic mechanism unit can particularly advantageously be integrated into forged and cast, especially standardized, rocker arms in a space- and weight-saving manner, with low manufacturing and installation complexity and in a cost-saving manner.

[0012] In a preferred design of the present invention, a check valve for hydraulically controlling the piston is provided. Preferably, a hydraulic medium can be loaded onto the piston via the check valve such that a hydraulic pressure buffer can be generated on the piston at the contact position to transmit the valve lift. Thus, the force can be transmitted from the rocker arm, via the piston that is held rigid by the hydraulic pressure buffer, to one or more gas exchange valves to effect valve operation.

[0013] Preferably, the check valve is pre-tensioned to the open state by a valve spring element. Thereby, the force flow between the rocker arm and the gas exchange valve can be interrupted by simply cutting off the hydraulic loading of the piston and resetting it to the non-contact basic position, thus interrupting the valve lift transmission. Here, the valve spring element ensures the rapid and effective opening of the check valve and ensures the rapid resetting of the piston to the non-contact basic position to close the valve lift. Additional hydraulic valves are avoided.

[0014] In order to adjust the maximum valve lift that can be transmitted to the piston, it is advantageous, preferably, that the piston is at least partially coaxially surrounded by a sleeve fixed to an adjusting screw and is arranged to be movable relative to the sleeve. At the contact position of the piston here, the relative movement of the piston relative to the adjusting screw is restricted by a stop in the sleeve, such that the stop position can move together with the adjusting screw by screwing in the adjusting screw, and the maximum valve lift that can be transmitted to the piston can be adjusted. For fixing, the sleeve can in particular be clamped, locked or welded to the adjusting screw. It is also conceivable that the sleeve and the adjusting screw are formed integrally.

[0015] Preferably, at the non-contact basic position of the piston here, the relative movement of the piston relative to the adjusting screw is restricted by a further stop in the sleeve. Preferably, the piston forms a circumferential flange protruding at the outer diameter at its free end, and the piston can abut against the further stop in the sleeve at the non-contact basic position through this circumferential flange.

[0016] In this way, when adjusting the maximum valve lift that can be transmitted to the piston, the stop positions not only at the contact position between the piston and the adjusting screw but also at the non-contact basic position can move together.

[0017] It is also advantageous that the stop includes a stop ring, which is fixed in a groove at the outer diameter of the piston and is arranged protruding thereon, such that the stop ring can move relative to the sleeve together with the piston and can abut against a stop formed on the sleeve at the contact position of the piston to restrict the relative movement.

[0018] Preferably, the stop is formed by a second sleeve fixed to the free end of the sleeve. The second sleeve can in particular be clamped or welded to the free end of the first sleeve for fixing.

[0019] In another preferably particularly simply constructed design of the present invention, the piston acts together with a return spring element such that the piston can be reset from the contact position to the non-contact basic position by the spring force in a state without hydraulic pressure to close the valve lift.

[0020] Another advantage can be achieved in such a way that the return spring element is arranged coaxially acting between the sleeve and the piston in the sleeve as a helical compression spring. Preferably, the piston is supported on the sleeve movably relative to the sleeve through the return spring element in the sleeve. Thereby, simple support of the piston and at the same time a particularly compact arrangement can be achieved.

[0021] Preferably, the return spring element is supported at one spring end on the second sleeve fixed to the free end of the sleeve and at the other spring end on the circumferential flange protruding from the outer diameter of the piston.

[0022] In this way, the second sleeve fixed to the first sleeve constitutes both a spring support for the return spring element and a stop for the piston in the contact position.

[0023] Preferably, according to the ratio of the size of the hydraulically loadable pressure surface of the piston and the cross-sectional area of the valve opening of the check valve, the spring force of the return spring element is designed to be greater than the spring force of the valve spring element. In this way, the valve spring element and the return spring element can be further optimized in terms of quickly and effectively opening the check valve and short switching times.

[0024] It is also particularly preferred that, as the material of the hydraulic structural unit in addition to the adjusting screw, preferably sheet metal, preferably steel sheet, is provided. Preferably, the piston and the sleeve can be respectively implemented as sheet metal forming members and can be simply and cost-effectively manufactured without cutting. By designing with sheet metal, a particularly light structure with lighter mass and weight can also be achieved, thereby further improving the switching dynamic performance of the hydraulic structural unit.

[0025] The object of the present invention is also achieved by a rocker arm for a valve mechanism of an internal combustion engine, the rocker arm having the aforementioned hydraulic structural unit. The hydraulic structural unit can be arranged on the rocker arm in a structurally simple manner to transmit the valve lift in the direct force flow between the rocker arm and at least one exchange valve of the internal combustion engine. Thus, the rocker arm, which is cost-effectively standardized, is configured to be hydraulically switchable in order to transmit and close the valve lift in a variable valve mechanism. The advantages described above also apply.

[0026] Preferably, the hydraulic structural unit is screwed into a threaded hole in the rocker arm here.

[0027] Preferably, the hydraulic structural unit can be reset from the contact position for transmitting the valve lift to at least one exchange valve of the internal combustion engine to the non-contact basic position for closing the valve lift through the valve contact surface in a state without hydraulic pressure. Preferably, by screwing the hydraulic structural unit into the threaded hole, the maximum valve lift that can be transmitted on the rocker arm at the contact position of the hydraulic structural unit can be adjusted.

[0028] In addition, the aforementioned rocker arm can be designed in particular by other features described below. Description of the Drawings

[0029] Other features claimed in the present invention are derived from the following description and the drawings further explaining the present invention. Shown therein:

[0030] Figure 1 A cross-sectional view of a hydraulic structural unit according to the present invention arranged in a rocker arm of a valve mechanism of an internal combustion engine in an activated operating state for valve lift transmission is shown,

[0031] Figure 2Shows a cross-sectional view of the hydraulic structural unit in a deactivated operating state for closing the valve lift,

[0032] Figure 3 Shows a perspective view of the hydraulic structural unit,

[0033] Figure 4 Shows the rocker arm in a standardized implementation before installing the hydraulic structural unit, having threaded holes for screwing in the hydraulic structural unit,

[0034] Figure 5 Shows the rocker arm with the hydraulic structural unit screwed into the threaded holes, Figure 4 in the,

[0035] Figure 6 Shows the rocker arm with the hydraulic structural unit in a deactivated operating state, Figure 4 in the side view of the rocker arm. Detailed description

[0036] In Figures 1 to 3 exemplarily shown are different views of the hydraulic structural unit 1 according to the invention for arrangement in a rocker arm of a valve mechanism of an internal combustion engine. Figure 5 And Figure 6 exemplarily shown is a rocker arm with such a hydraulic structural unit 1 according to the invention.

[0037] The hydraulic structural unit 1 is used to transmit the valve lift on the rocker arm and is arranged in the force flow between the rocker arm and at least one intake and exhaust valve to be actuated of the internal combustion engine. According to Figures 1 to 3 , the hydraulic structural unit has an adjusting screw 2 for guiding the hydraulic medium, which is screwed into the internal thread 5 of the threaded hole 6 through an elongated column 3 with an external thread 4. The threaded hole penetrates between the end of the valve-side lever arm 7 of the rocker arm, the upper lever side facing away from the valve, and the lower lever side facing the valve. The adjusting screw 2 is fixed by a lock nut 29 at the upper end protruding from the threaded hole 6 at the upper lever side facing away from the valve. Here, the adjusting screw has a free end section 8 that widens radially compared to the column 3 at the outer diameter and protrudes from the threaded hole 6 at the lower lever side facing the valve.

[0038] The hydraulic structural unit 1 further includes a cylindrical piston 9, which is implemented in a basin shape and is open on one side. The piston 9 is preferably implemented in a plate. The piston is socketed in a movable manner relative to the adjusting screw on the outer diameter or outer circumference of the protruding free end section 8 of the adjusting screw 2 through the open end with an inner diameter or inner circumference, such that the free end section 8 and the piston 9 define a hydraulic pressure chamber 10. The adjusting screw 2 with the free end section 8 and the piston 9 are coaxially arranged with respect to the central axis 11, and the piston 9 is guided on it in a movable manner along the central axis relative to the free end section 8 of the adjusting screw 2.

[0039] The pressure chamber 10 is hydraulically connected to the hydraulic medium storage chamber 13 formed in the adjusting screw 2 via a check valve 12. The latter can be loaded with hydraulic medium via a hydraulic medium connection 14 formed in the rocker. The loading of the hydraulic medium can be switched on and off by a preferably electrically controllable valve (not shown), in particular by an electromagnetic valve.

[0040] The hydraulic medium storage chamber 13 is partially formed in the column 3 and partially formed in the end section 8. The hydraulic medium storage chamber 13 is connected to a receiving chamber 15 which is widened relative to the hydraulic medium storage chamber 13 and is formed in the end section 8. The receiving chamber opens towards the free end of the end section 5. An insert 16 is received in the receiving chamber 15. The check valve 12 is formed and held in the insert 16, and the insert simultaneously defines the hydraulic medium storage chamber 13.

[0041] The pressure chamber 10 can be loaded with hydraulic medium from the hydraulic medium storage chamber 13 via the check valve 12, and the piston 9 can be loaded with hydraulic medium on a pressure surface 17 which forms the basin-shaped closed end on the inside in the pressure chamber 10. The pressure surface serves as a hydraulically acting piston surface. The pressure chamber forms a flat valve contact surface on the outside facing away from the pressure surface 17. The pressure chamber can be placed against an unshown operating gas exchange valve with the valve contact surface to transmit the valve lift. It is also conceivable that the piston 9 can be placed against a transmission element, such as a valve bridge, with the valve contact surface 18 to transmit the valve lift. In this way, the piston 9 is directly arranged in the force flow between the rocker and the unshown operating gas exchange valve to transmit the valve lift.

[0042] The check valve 12 is embodied as a ball valve and has a valve spring element 19 which pre-tensions a valve ball 21 for closing a valve opening 20 into an open state. A helical compression spring arranged in the valve opening 20 serves as the valve spring element 19.

[0043] Figure 1 The hydraulic structural unit 1 is shown in an activated state. The piston 9 is guided relative to the housing on the housing, against the spring force of a return spring element 22, and projects maximally relative to the basic position by the full piston lift H into a contact position for transmitting the valve lift. The basic position and the contact position of the piston 9 are each shown by a dashed line. Here, the piston 9 is in direct or indirect contact with at least one unshown gas exchange valve with the valve contact surface 18.

[0044] The return spring element 22 is arranged coaxially on the outer circumference of the piston 9 as a helical compression spring. When the piston 9 projects into the contact position according to Figure 1 , the return spring element 22 is compressed as shown in Figure 1 , and the return spring element 22 is pre-tensioned to reset the piston 9 into the Figure 2 shown non-contact basic position to close the valve lift.

[0045] In the unloaded and hydraulically unpressurized state of the piston 9, the check valve 12 can be held open by the spring force of the valve spring member 19. Thus, in order to reset the piston to the Figure 2 non-contact basic position according to, the hydraulic medium can be pressed out of the pressure chamber 10 through the piston 9 via the check valve 12 pre-tensioned to the open state by the valve spring member 19 into the hydraulic medium storage chamber 13. In Figure 2 the contact position and the basic position of the piston 9 and the reset piston lift H are again shown by dashed lines respectively.

[0046] In this case, the greater the spring force of the reset spring member 22 acting on the piston 9, the faster the hydraulic medium can be pressed out of the pressure chamber 10 through the piston 9, and the faster the piston 9 can be reset to the non-contact basic position to close the valve lift.

[0047] In order to optimally set the ratio of the force-pressure-acting surface of the valve spring member 12 to the reset spring member 22, preferably according to the ratio of the size of the pressure surface 17 of the piston 9 to the cross-sectional area of the valve opening 20 of the check valve 12, the spring force of the reset spring member 22 is designed to be greater than the spring force of the valve spring member 19. This ensures the reliable opening of the check valve 12 to reset the piston 9 and at the same time ensures a high reset speed for closing the valve lift.

[0048] In order to activate the hydraulic structural unit 1 to transmit the valve lift according to Figure 1 the described electrically controllable valve or solenoid valve is actuated so that the hydraulic medium storage chamber 13 is loaded with hydraulic medium via the hydraulic medium connection 14 in the rocker and the pressure chamber 10 is loaded with hydraulic medium via the check valve 12. If the piston is unloaded, the piston is pressed out to the Figure 1 contact position for transmitting the valve lift according to.

[0049] If the rocker deflected for operating the valve presses the extended piston 9 against the gas exchange valve to transmit the valve lift here, the hydraulic medium pressure in the pressure chamber 10 rises sharply, the valve ball 21 closes the valve opening 20 leading to the hydraulic medium storage chamber 13, whereby the hydraulic medium can only flow away via the defined leakage gap formed between the piston 9 and the end section 8 of the adjusting screw 2, so that the piston 9 is firmly held by the hydraulic pressure buffer contained in the pressure chamber 10, and the valve lift of the rocker can be transmitted to the gas exchange valve to be operated via the piston 9. Here, the valve clearance existing in the assembly can be compensated at the same time.

[0050] The proposed hydraulic unit 1 can simultaneously adjust the piston 9 in a particularly simple manner in Figure 1The maximum valve lift that can be transmitted on the piston contact surface 18 at the contact position shown. For this purpose, a sleeve 23 is provided which is arranged coaxially with the free end section 8 of the adjusting screw 2, and the piston 9 is guided movably on the sleeve.( Figure 1 and Figure 2 ). Starting from the interface of the widened end section 8 on the column 3 of the adjusting screw 2, the sleeve 23 surrounds the end section 8 and the piston 9 which can be guided with its free end thereon, wherein the free end of the end section 8 and the piston 9 having the valve contact surface 18 guided thereon project beyond the axial free end of the sleeve 23.

[0051] The sleeve 23 is radially connected to the outer diameter of the column 3 by means of an axially facing end of the column 3 with a basin-shaped radially inwardly extending annular flange 24, and is axially connected to the free end side of the end section 5 facing the column. For fixing, the sleeve 23 can be screwed, locked or welded, for example, to the adjusting screw 2.

[0052] Here, the inner diameter of the sleeve 23, and thus the inner circumference, and the outer diameter of the piston 9 which is movably sleeved on the end section 8 and guided thereon, and thus the outer circumference, are arranged radially spaced apart. Thereby, an annular space is defined radially between the sleeve 23 and the piston 9, and the return spring element 22 is coaxially arranged acting in this annular space between the piston 9 and the sleeve 23.

[0053] The relative movement of the piston 9 relative to the sleeve 23 is defined by a stop in the contact position of the piston 9. For this purpose, a second sleeve 25 is preferably coaxially sleeved on the free end of the sleeve 23, and it is fixed to the outer diameter of the first sleeve 23 with its inner diameter. The latter is provided with a radially inwardly extending annular flange 26 which axially defines an annular space. Preferably, the sleeves 23, 25 are each made of sheet metal.

[0054] A stop ring 27 is provided on the piston 9, which is fastened in a groove 28 on the outer diameter of the piston 9 and projects therefrom, such that the stop ring abuts against the flange 26 movably with the piston 9 relative to the sleeve 23 to define the relative movement of the piston 9 relative to the sleeve 23, and the flange is formed on the second sleeve 25 and serves as a stop in the contact position of the piston 9 for transmitting the maximum valve lift.

[0055] The flange 26 formed on the second sleeve 25 simultaneously serves as a spring support for the return spring element 22. The spring return member is supported at one spring end on the flange 26 and at the other spring end on the flange 30 which projects radially from the outer diameter of the free end of the piston 9.

[0056] Thus, by screwing the adjusting screw 2 into the threaded hole 6, the sleeve 23 fixed to the adjusting screw 2, the second sleeve 25 with a flange 26 fixed to the sleeve, and thus the stop position in the contact position of the piston 9 can move axially together with the adjusting screw 2 relative to the lever arm 7 on the valve side, and thus the maximum valve lift that can be transmitted on the piston 9 on the valve contact surface 18 can be set arbitrarily.

[0057] At the same time, the piston 9 is prevented from falling out by the return spring member 22, the stop ring 27, and the second sleeve 25 with a flange 26.

[0058] To define the relative movement of the piston 9 relative to the adjusting screw 2 in the non-contact basic position, the piston 9 can rest flat against the flange 24 with a flange 30, which is formed on the first sleeve 23 and serves as a stop in the basic position. In this way, the piston lift H of the piston 2 in the contact position relative to the basic position can be precisely set by the stops 24, 26. At the same time, thereby by the adjusting screw 2, the piston 9 can be moved in the contact position and the stop positions of the non-contact basic position when screwed in.

[0059] For exhaust and to allow the hydraulic medium to pass through, a plurality of axially distributed through-holes 34 are provided on the flange 24 ( Figures 1 to 3 ).

[0060] Figure 3 A perspective view of the hydraulic structural unit 1 is shown. The hydraulic structural unit can be screwed into the threaded hole 6 at the end of the lever arm 7 on the valve side of the rocker arm implemented in a standardized manner through the external thread 4 of the column 3 of the adjusting screw 2. The adjusting screw 2 is provided with a contour 31, here in the shape of an internal hexagon, at one axial end side for the form-fitting engagement of the tightening tool ( Figure 4 , Figures 1 to 3 , Figure 5 and Figure 6 ), and the tightening tool can screw the adjusting screw into the threaded hole 6 on the rocker arm.

[0061] Figure 5 and Figure 6 show the Figure 4 rocker arm in which the hydraulic structural unit 1 has been screwed into the threaded hole 6. The rocker arm is preferably implemented in a standardized manner for use in forged components of heavy or medium-duty load internal combustion engines.

[0062] The hydraulic structural unit 1 is arranged in the threaded hole 6 to directly transmit the valve lift in the force flow between the lever arm 7 on the valve side and an inoperative gas exchange valve (not shown) of an internal combustion engine. Here, the hydraulic structural unit is screwed into the threaded hole 6 with an adjusting screw 2 having a column 3 at the lower side of the lever, such that the piston 9 projects with a valve contact surface 18 at the lower side of the lever to transmit the valve lift, and the adjusting screw 2 is fixedly secured to the lever arm 7 on the valve side at the upper side of the lever with a lock nut screwed onto the upper end of the column 3. By screwing the adjusting screw 2 into the threaded hole 6, the maximum valve lift that can be transmitted at the rocker on the hydraulic structural unit 1 can be adjusted.

[0063] The rocker can be driven on the lever arm 32 on the drive side directly via a camshaft (not shown) via an acting element (not shown), such as a cam roller, or indirectly via a tappet having a cam lift movement to operate the valve. Here, the rocker is pivotally arranged about its axis (not shown) with the lever arms 7, 32. For this purpose, a receiving opening 33 for passing through the rocker axis is provided in the intermediate region of the rocker located between the lever arms 7, 32. An oil supply hole (not shown) is configured at the inner diameter of the receiving opening 35, and the rocker, in particular the hydraulic medium connection 14 on the lever arm 7 on the valve side, can be supplied with hydraulic medium via the oil supply hole through the rocker axis. Preferably, oil from the engine circuit is used as the hydraulic medium.

[0064] Figure 1 The rocker with the activated hydraulic structural unit 1 is shown. The piston 9 is loaded with hydraulic medium and projects from the non-contact basic position to the contact position with a full piston lift H. The non-contact basic position and the contact position are each shown by a dashed line.

[0065] Here, the rocker contacts at least one inoperative gas exchange valve (not shown) directly or indirectly via a transmission element with the valve contact surface 18. In this case, by screwing the adjusting screw 2 into the threaded hole 6, any predetermined maximum valve lift that can be transmitted at the hydraulic structural unit 1 and the rocker can be set.

[0066] In Figure 2 and Figure 6 the hydraulic structural unit 1 is deactivated. For this purpose, the loading of the piston 9 with hydraulic medium is interrupted. Here, the piston 9 returns from the contact position to the non-contact basic position by the spring force of a return spring element 22 and retracts into the threaded hole 6. The non-contact basic position and the contact position are also each shown by a dashed line.

[0067] Thereby, in the cam base circle phase of the drive cam, the piston 9 is arranged at a distance from the inoperative gas exchange valve or a transmission element for transmitting the valve lift with the length of the piston lift H by means of the valve contact surface 18.

[0068] If the rocker is in the pivoting position of the piston 9 that has the hydraulic structural unit 1 deactivated and returns to the contactless basic position during the cam lift phase, the rocker is arranged at a distance from the gas exchange valve or the transmission element for transmitting the valve lift by means of an air gap of length S during the maximum deflection or pivoting of the valve-side lever arm 7 with the valve contact surface 18. Thereby, the rocker executes an idle stroke, such that the valve lift cannot be transmitted to the hydraulic structural unit 1 and to the rocker arm, and the valve lift is closed.

[0069] The size of the air gap or the spacing length S can be adjusted by means of the piston lift H and is preferably selected such that operating disturbances are reliably avoided under the specific operating and running conditions of the internal combustion engine, in particular operating disturbances caused by thermally induced length changes of the components during operation, especially collisions between the open gas exchange valve and the working piston of the internal combustion engine during engine braking operation.

[0070] List of Reference Signs

[0071] 1 Hydraulic structural unit

[0072] 2 Adjusting screw

[0073] 3 Column

[0074] 4 External thread

[0075] 5 Internal thread

[0076] 6 Threaded hole

[0077] 7 Valve-side lever arm

[0078] 8 End section

[0079] 9 Piston

[0080] 10 Pressure chamber

[0081] 11 Central axis

[0082] 12 Check valve

[0083] 13 Hydraulic medium storage chamber

[0084] 14 Hydraulic medium connection

[0085] 15 Receiving chamber

[0086] 16 Insert

[0087] 17 Pressure surface

[0088] 18 Valve contact surface

[0089] 19 Valve spring element

[0090] 20 Valve opening

[0091] 21 Valve ball

[0092] 22 Return spring member

[0093] 23 First sleeve

[0094] 24 Flange, stop in the basic position

[0095] 25 Second sleeve

[0096] 26 Flange, stop in the contact position

[0097] 27 Stop ring

[0098] 28 Groove

[0099] 29 Locking nut

[0100] 30 Flange

[0101] 31 Profile

[0102] 32 Lever arm on the drive side

[0103] 33 Receiving port

[0104] 34 Flow port

[0105] H Piston lift

[0106] S Air gap, spacer length

Claims

1. A hydraulic structural unit (1) for being arranged in a rocker arm of a valve train of an internal combustion engine, characterized in that An adjusting screw (2) for guiding a hydraulic medium is provided, the adjusting screw being used to be screwed into a threaded hole (6) on the rocking arm, wherein a piston (9) having a valve contact surface (18) through which the hydraulic medium can be loaded can be movably mounted on the adjusting screw (2) to transmit a valve lift, so that the piston (9) can be reset from a contact position for transmitting the valve lift to a contactless basic position for closing the valve lift in a state without hydraulic pressure, and by screwing in the adjusting screw (2), the maximum valve lift that can be transmitted on the rocking arm at the contact position of the piston (9) can be adjusted.

2. The hydraulic structural unit (1) according to claim 1, characterized in that: A check valve (12) is provided for hydraulically controlling the piston (9), and the piston can be loaded with a hydraulic medium via the check valve (12) to transmit a valve lift in a contact position, wherein, in a state of the piston (9) without hydraulic pressure, the hydraulic medium can be returned via the check valve (12) to reset the piston to a contact-free basic position.

3. The hydraulic structural unit (1) according to claim 2, characterized in that: The nonreturn valve (12) is pretensioned into an open state by a valve spring element (19).

4. The hydraulic structural unit (1) according to any one of claims 1 to 3, characterized in that: The piston (9) is at least partially coaxially surrounded by a sleeve (23) fixed to the adjusting screw (2) and is arranged to be movable relative to the adjusting screw (2), wherein, in the contact position of the piston (9), the relative movement of the piston (9) relative to the adjusting screw (2) is limited by a stop member (26, 27) in the sleeve (23), so that the stop position can move together with the adjusting screw by screwing in the adjusting screw (2) and can adjust the maximum valve lift that can be transmitted on the piston (9).

5. The hydraulic structural unit (1) according to claim 4, characterized in that: In the contact-free basic position of the piston (2), the relative movement of the piston (9) relative to the adjusting screw (2) is limited in the sleeve (23) by a further stop (24).

6. The hydraulic structural unit (1) according to claim 4 or 5, characterized in that: The stop member comprises a stop ring (27), which is fixed in a groove (28) at the outer diameter of the piston (9) and is arranged protruding thereon, so that the stop ring and the piston (9) can move relative to the sleeve (23) and can abut against a stop (26) formed on the sleeve (23) in the contact position of the piston (9) to limit the relative movement.

7. The hydraulic structural unit (1) according to claim 6, characterized in that: The stop (26) is formed by a second sleeve (25) which is fixed to the free end of the sleeve (23).

8. The hydraulic structural unit (1) according to any one of claims 1 to 7, characterized in that: The piston (9) cooperates with a return spring element (22) to return to a contact-free basic position.

9. The hydraulic structural unit (1) according to claim 8, characterized in that: The return spring element (22) is arranged coaxially as a helical compression spring in the sleeve (23) between the sleeve and the piston (9).

10. A rocker lever for a valve train of an internal combustion engine, the rocker lever comprising at least one hydraulic unit (1) according to any one of claims 1 to 9.

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