Switchable rocker arm for a valve train of an internal combustion engine with a rotation lock for its coupling piston.

Abstract

Switchable rocker arm (1) for a valve train of an internal combustion engine, with an outer lever (2) which encloses an inner lever (3) which is pivotable relative to it, at least which inner lever (3) has a lift cam contact surface (4), wherein the outer lever (2) has on its underside (5) at one longitudinal end (6) a support element bearing surface (7) and at another longitudinal end (8) a gas exchange valve assembly (42), at which other longitudinal end (8) the inner lever (3, 2) is connected to the outer lever (3, 2) via a pivot axis (10), wherein the outer lever (2) is provided on its upper side (11) at one longitudinal end (6) with a guide housing (12) having a bore (13) extending in the longitudinal direction of the rocker arm (1) with a coupling piston (14) therein, the piston having a sectional flattening (17) on its upper side (16) starting from its end face (15) furthest from the bore,via which, in the case of coupling, it can be displaced under a drive surface (18) of an end transverse web (19) of the inner lever (3), wherein a cam return spring element (20) acts between the inner and outer levers (3, 2) and wherein the coupling piston (14) is secured by an anti-rotation element (21), characterized in that the anti-rotation element (21) is in the form of a U-shaped spring plate, which extends with its transverse web (22) over an upper face (23) of the guide housing (12) and is spring-loaded with legs (9) hanging from both ends of the transverse web (22) on side surfaces (24) of the guide housing (12), wherein the guide housing (12) has a transverse slot (25) extending from its upper face (23) and through to its bore (13), in which a tab projecting from the transverse web (22) of the spring plate (21) (26) is inside,which, by means of a transverse face (27), interacts with the flattened surface (17) of the coupling piston (14) to prevent its rotation, and wherein the tab (26) is simultaneously provided with a lifting-off device (28, 34) for the spring plate (21) from the guide housing (12).

Description

[0001] The invention relates to a switchable rocker arm for a valve train of an internal combustion engine, comprising an outer lever which encloses an inner lever which is pivotable relative to the outer lever, at least which inner lever has a lift cam contact surface, wherein the outer lever has a support element bearing surface at one longitudinal end on its underside and a gas exchange valve assembly at another longitudinal end, at which other longitudinal end the inner lever is connected to the outer lever via a pivot axis, wherein the outer lever is provided at its upper side at one longitudinal end with a guide housing having a bore extending in the longitudinal direction of the rocker arm and a coupling piston therein, the piston having a section-wise flattening on its upper side starting from its end face furthest from the bore, over which it can be displaced under a drive surface of an end transverse web of the inner lever in the coupling case.wherein a cam return spring means acts between the inner and outer levers and wherein the coupling piston is secured by an anti-rotation device.

[0002] DE 10 2015 215 278 A1 discloses a switchable rocker arm as described above with an anti-rotation device designed as a pin / needle. The latter is mounted at both ends in the guide housing of the outer lever and covers the flattened area of ​​the coupling piston. The anti-rotation device is connected to the outer lever at its end faces via an ultrasonic weld.

[0003] According to DE 10 2016 219 705 A1, a spring-groove connection is provided as an anti-rotation device for the flattened coupling piston of a switchable rocker arm.

[0004] The task is to design a switchable rocker arm that has a simple and easily mountable anti-rotation device for its coupling piston.

[0005] According to the invention, this problem is solved by providing the anti-rotation device as a U-shaped spring plate, which extends with its transverse web over an upper face of the guide housing and is spring-loaded to side surfaces of the guide housing by means of legs hanging from both ends of the transverse web, wherein the guide housing has a transverse slot extending from its upper face and through to its bore, in which a tab projecting from the transverse web of the spring plate is inserted, which interacts with the flattening of the coupling piston by means of a transverse face to prevent its rotation, and wherein the tab is simultaneously provided with a lifting-off device for the spring plate from the guide housing.

[0006] The innovative spring plate, a simple stamped sheet metal part, is attached to the guide housing by simply pushing it on and clipping / snapping it into place. The essential anti-lift device for the spring plate is achieved by its bent tab. In addition to the spring plate's ease of installation, its non-destructive removal is a key advantage. Furthermore, the tab provides the coupling piston with a slightly spring-loaded end stop in its coupling direction. The coupling piston can also be actuated directly or indirectly in at least one direction via another slide-type piston with a ramp mechanism and / or can itself run transversely to the longitudinal extent of the rocker arm.

[0007] Particularly preferred embodiments of the invention relate to advantageous designs of the spring plate's tab. For example, the tab can be configured as a loop-like bent tongue with a first and second tongue section, the transverse end being located at the apex connecting these two sections. The free end of this second tongue section is simply snapped under the bore on the second, lever-side tongue section to act as a safety device against lifting.

[0008] Alternatively, it is proposed to return a free end on the second tongue piece through the transverse slot to the upper face of the guide housing, with the second tongue piece engaging under the bore as the anti-lift device in the direction of travel after the apex with a bulge.

[0009] The tab is inserted into the transverse slot of the guide housing by simply squeezing it together. Due to its spring-like properties, the tab prevents the coupling piston from twisting, thus minimizing wear.

[0010] According to a further development of the invention, it is proposed to additionally lock the legs of the spring plate, which are guided around the guide housing, there. In this case, the legs have slightly inwardly bent sections at their ends, which engage in transverse grooves of the guide housing.

[0011] Furthermore, a simple longitudinal stop is provided for the crossbar of the spring plate on the upper face of the guide housing. For this purpose, the upper face has at least two steps, with the crossbar abutting a transverse wall between the steps with its end facing away from the tab. If necessary, the spring plate can also be installed such that its tab is located on the opposite longitudinal side, so that the step on the upper face of the guide housing is correspondingly reversed.

[0012] A suitable servo device for actuating the coupling piston is the subject of a further dependent claim. According to this claim, the coupling piston is to be actuated in at least one of its two displacement directions via hydraulic means, for example, in its decoupling direction, whereby its displacement can be achieved, for example, via a compression spring force. Thus, a coupled state is realized at the rocker arm when no hydraulic pressure is applied. Alternatively, internal or external electromagnetic or other mechanical actuation of the coupling slide is also possible.

[0013] Finally, the rocker arm is intended to be designed simply as a stroke switch, with only the inner lever having a roller as a cam contact surface. Alternatively, the inner lever can also be designed with a sliding pad or similar for a stroke cam contact.

[0014] Regarding the drawing: • Fig. Figure 1 shows a switchable rocker arm in spatial view with a first variant of an anti-rotation device; • Fig. Figure 2 shows a partial longitudinal section through the aforementioned trailing arm in the section from one end of it; • Fig. Figure 3 shows in detail the anti-rotation device, which is in the form of a U-shaped spring plate, according to the preceding figures; • Fig. Figure 4 shows a partial longitudinal section through the switchable rocker arm in the section from one end of its body with a second variant of its anti-rotation device and • Fig. Figure 5 shows in detail the anti-rotation device, which is in the form of a U-shaped spring plate, according to Fig. 4.

[0015] The one from Fig. The resulting switchable rocker arm 1 consists of a box-shaped outer lever 2, which encloses an inner lever 3 that can pivot relative to it and has a lifting cam contact surface 4 designed as a roller. The outer lever 2 has a support element bearing surface 7, shaped like a spherical cap, at one longitudinal end 6 (shown here on the left) on its underside 5. At its other longitudinal end 8 (shown here on the right), the outer lever 2 has a gas exchange valve assembly 42 on its underside 5.

[0016] This can be seen in Fig. 1, that at the other longitudinal end 8 the outer lever 2 has a dome 43 with a pivot axis 10. At the end face of the pivot axis 10, the inner lever 3, 2 is rotatably connected to the outer lever 3, 2.

[0017] The outer lever 2 is provided with a guide housing 12 on its upper side 11 at one longitudinal end 6. A coupling piston 14 (sa) runs in a bore 13 of the box-shaped guide housing 12, which extends longitudinally along the rocker arm 1. Fig. 2, Fig. 4) The latter is not cylindrical throughout. Rather, starting from its end face 15 furthest from the bore, it has a sectional flattening 17 on its upper surface 16. It is shaped like the Fig. 2, Fig. As can be seen from Figure 4, in a coupling case, the inner lever 3 can be displaced with the outer lever 2 under a drive surface 18 of an end crossbar 19 of the inner lever 3 by the force of a compression spring 44. A return displacement of the coupling piston 14 is accomplished by hydraulic means, which can be directed via the support element bearing surface 7 of the outer lever 2 into a pressure chamber 40 in front of a pressure face 41 of the coupling piston 14. In addition, the inner and outer levers 3 and 2 are pre-tensioned by a cam return spring 20, which is also referred to as a lost-motion spring.

[0018] The coupling piston 14 is secured by an anti-rotation device 21. In both variants, which will be explained in more detail below, the anti-rotation device 21 is a U-shaped spring plate. As shown in the following diagram... Fig. The latter, which is removable, extends with its crossbar 22 over an upper surface 23 of the guide housing 12. Legs 9 hang from the crossbar 22 on both sides and are spring-loaded against side surfaces 24 of the guide housing 12. Fig. 1 indicates that the legs 9 are additionally engaged at their ends in transverse grooves 35 of the guide housing 12.

[0019] The guide housing 12 has, as can be seen from the Fig. 1, Fig. 2 and 4 removable, a transverse slot 25 extending from its upper face 23 and through to the bore 13. A tab 26 bent from the transverse web 22 of the spring plate 21 projects into this slot, which originates from one side of the transverse web 22 facing the other longitudinal end 8.

[0020] According to the variant according to the Fig. In sections 1-3, the tab 26 is formed as a loop-like bending tongue with a first and second tongue section 29, 30. A transverse face 27 of the tab 26, located at a vertex connecting the tongue sections 29, 30, provides anti-rotation protection for the coupling piston 14, such that the transverse face 27 runs directly in front of / on the flattened surface 17 of the coupling piston 14. Fig. Figure 2 shows that a free end 31 of the second tongue piece 30 has snapped under the bore 13, so that a lifting protection 28 for the spring plate 21 is present, thus securing it against falling out of the transverse slot 25.

[0021] The Fig. 4, Fig. Figure 5 shows another variant of the spring plate 21. A free end 32 on the second tongue piece 30 of the tab 26 is guided back through the transverse slot 25 onto the upper face 23 of the guide housing 12. At the same time, the second tongue piece 30 engages with a protrusion 33 under the bore 13 to form the anti-lift device 34.

[0022] Furthermore, how from Fig. The upper face 23 of the guide housing 12, viewed in the longitudinal direction of the trailing arm 1, is stepped downwards from one longitudinal end 6 to the other longitudinal end 8. Two steps 36, 37 are indicated. The transverse web 22 of the spring plate 21, for further position fixing, abuts with its transverse face 38 facing away from the tab 26 against a transverse wall 39 between the steps 36, 37. Reference symbol list 1 rocker arm 2 external levers 3 inner levers 4 Hub cam contact surface 5 Underside 6 Long end (of one) 7 Support element bearing surface 8 Long end (other) 9 thighs 10 Swivel axis 11 Top (Outer Lever) 12 guide housings 13 bore 14 coupling pistons 15 Forehead (far from the drill hole) 16 Top side (coupling piston) 17 Flattening 18 drive area 19 Crossbar (Inner lever) 20 Cam return spring components 21 Anti-rotation device, spring plate 22 Crossbar (spring plate) 23 Upper forehead 24 side surface 25 cross slots 26 tab 27 Transverse forehead 28 Lift-off protection 29 Tongue piece (first) 30 tongue piece (second) 31 End 32 End 33 Bulge 34 Lift-off protection 35 transverse groove 36th level 37th level 38 Transverse forehead 39 Cross wall 40 printing room 41 Pressure forehead 42 Gas exchange valve system 43 Cathedral 44 Compression spring components QUOTES INCLUDED IN THE DESCRIPTION

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

[0000] DE 10 2015 215 278 A1

[0002] DE 10 2016 219 705 A1

[0003]

Claims

Switchable rocker arm (1) for a valve train of an internal combustion engine, with an outer lever (2) which encloses an inner lever (3) which is pivotable relative to it, at least which inner lever (3) has a lift cam contact surface (4), wherein the outer lever (2) has on its underside (5) at one longitudinal end (6) a support element bearing surface (7) and at another longitudinal end (8) a gas exchange valve assembly (42), at which other longitudinal end (8) the inner lever (3, 2) is connected to the outer lever (3, 2) via a pivot axis (10), wherein the outer lever (2) is provided on its upper side (11) at one longitudinal end (6) with a guide housing (12) having a bore (13) extending in the longitudinal direction of the rocker arm (1) with a coupling piston (14) therein, the piston having a sectional flattening (17) on its upper side (16) starting from its end face (15) furthest from the bore,via which, in the case of coupling, it can be displaced under a drive surface (18) of an end transverse web (19) of the inner lever (3), wherein a cam return spring element (20) acts between the inner and outer levers (3, 2) and wherein the coupling piston (14) is secured by an anti-rotation element (21), characterized in that the anti-rotation element (21) is in the form of a U-shaped spring plate, which extends with its transverse web (22) over an upper face (23) of the guide housing (12) and is spring-loaded with legs (9) hanging from both ends of the transverse web (22) on side surfaces (24) of the guide housing (12), wherein the guide housing (12) has a transverse slot (25) extending from its upper face (23) and through to its bore (13), in which a tab projecting from the transverse web (22) of the spring plate (21) (26) is inside,which, by means of a transverse face (27), interacts with the flattened surface (17) of the coupling piston (14) to prevent its rotation, and wherein the tab (26) is simultaneously provided with a lifting-off device (28, 34) for the spring plate (21) from the guide housing (12). Switchable rocker arm according to claim 1, characterized in that the tab (26) of the spring sheet (21) is provided as a loop-like bending tongue with a first and second tongue piece (29, 30), wherein the transverse front (27) is located at a vertex connecting these and wherein its free end (31) is snapped into the bore (13) as the lifting safety device (28) on the second tongue piece (30). Switchable rocker arm according to claim 1, characterized in that the tab (26) of the spring sheet (21) is provided as a loop-like bending tongue with a first and second tongue piece (29, 30), wherein the transverse end (27) is located at a vertex connecting these and its free end (32) is guided back to the upper end (23) of the guide housing (12) opposite the transverse web (22) of the spring sheet (21) on the second tongue piece (30) through the transverse slot (25), wherein the second tongue piece (30) engages in the direction of travel after the vertex with a protrusion (33) under the bore (13) as the anti-lift device (34). Switchable rocker arm according to one of the preceding claims, characterized in that the legs (9) of the spring plate (21) are engaged at their ends in the respective transverse grooves (35) of the guide housing (12). Switchable tow lever according to claim 1, characterized in that the upper end face (23) of the guide housing (12) is provided with at least two steps (36, 37) in the longitudinal direction of the tow lever (1), wherein the transverse web (22) of the spring plate (21) with its transverse end face (38) facing away from the tab (26) abuts a transverse wall (39) between the steps (36, 37). Switchable rocker arm according to claim 1, characterized in that the coupling piston (14) is displaceable in at least one of its displacement directions via hydraulic means, which can be directed via the support element bearing surface (7) of the outer lever (2) into a pressure chamber (40) enclosed by its bore (13) in front of a pressure face (41) of the coupling piston (14). Switchable rocker arm according to claim 1, characterized in that the rocker arm (1) is provided as a stroke cut-off switch, wherein only the inner lever (3) has the stroke cam contact surface (4) designed as a roller.

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