Rocker arm for a valve train of an internal combustion engine

Abstract

Rocker arm (1) for a valve train of an internal combustion engine, which rocker arm (1) is intended for vertical installation, comprising a hydraulic insert element (4) with a piston (5) and a housing (6) seated in a receptacle (2) on the valve-side longitudinal side (3) of which the insert element (4) has a piston (5) and a housing (6), wherein the piston (5), which encloses a reservoir (8) for hydraulic fluid via its inner shell (7), bears at least indirectly against a base (10) of the receptacle (2) via its annular end face (9), and the housing (6), which encloses the piston (5) with its bore (11), extends axially movably in the receptacle (2) via its outer shell (12), and has a valve-side contact foot (13) for a follower element (29), wherein a high-pressure chamber (16) for hydraulic fluid is formed between a valve-side web (14) of the piston (5) and a base (15) of the housing (6), which is controlled by a check valve applied to the web (14). (17) can be supplied with hydraulic fluid,wherein means for preventing leakage of the reservoir (8) are provided, such that a separate disc-like closure body (18) is fixedly seated on the inner shell (7) of the piston (5), directly at its annular end face (9), which has a through-bore (20) arranged immediately in front of its outer edge (19), which in the case of vertical installation is located at a geodetically highest point, and wherein a separate pin (21) is provided for preventing rotation of the piston (5) relative to the receptacle (2), which is seated at one end in a bore (23) extending from an end face (22) of the rocker arm (1) and intersecting its receptacle (2), and at the other end engages in a recess (24) of the piston (5) at its annular end face (9).

Description

[0001] The invention relates to a rocker arm for a valve train of an internal combustion engine, which rocker arm is intended for vertical installation, comprising a hydraulic plug-in element seated in a receptacle on the valve-side longitudinal side thereof, with a piston and a housing, wherein the piston, which encloses a reservoir for hydraulic fluid via its inner jacket, rests at least indirectly on a base of the receptacle via its annular end, and the housing, which encloses the piston with its bore, extends axially movable in the receptacle via its outer jacket and has a valve-side contact foot for a follower element, wherein a high-pressure chamber for hydraulic fluid is formed between a valve-side web of the piston and a bottom of the housing, which high-pressure chamber can be supplied with hydraulic fluid via a check valve applied to the web, and wherein means for preventing the reservoir from leaking are provided such that on the inner jacket of the piston,directly at the annular end, a closure body is firmly seated, which has a through hole arranged directly in front of its outer edge, which in the case of vertical shoring is located at a geodetically highest point.

[0002] A rocker arm of this type, intended for vertical installation, is disclosed in DE 10 2021 114 644 A1. The closure body for preventing leakage from the piston's reservoir has a multi-part design. On the one hand, it consists of a cap-like base body. On the other hand, a radial web protrudes from the base body, which sits in a guide groove of the rocker arm mount.

[0003] The task is to propose a rocker arm for a vertical shoring whose means for preventing leakage of the piston storage space are simplified.

[0004] According to the invention, this object is achieved in that the closure body is a circumferentially disc-like body without radial projections and wherein a separate pin is provided to prevent the piston from rotating relative to the receptacle, which pin is seated at one end in a bore extending from an end face of the rocker arm and intersecting its receptacle and at the other end engages in a recess in the piston at its annular face.

[0005] This results in a rocker arm with a horizontal or nearly horizontal insert element, whose leak-prevention features are simplified and easy to install. The elimination of the longitudinal groove in the rocker arm mount is particularly advantageous here. The pin, which can also be polygonal or have a mushroom-shaped geometry, is preferably pressed into the lever bore. It can, for example, be joined to the bore before the insert element is inserted into the mount.

[0006] The term "rocker arm" also includes cam followers that are mounted at one end on an axle (rocker arm) or a support element (finger arm). It is also clear that the term "hydraulic insert element" refers to a hydraulic lash adjuster.

[0007] The use of the rocker arm, which in the "rest position" (internal combustion engine at a standstill and cam base circle contact) does not necessarily have to be exactly parallel to the vertical with its longitudinal extension and can also be arranged so that its one-ended plug-in element is upside down, is conceivable, for example, in the valve trains of boxer engines or engines that function as "range extenders". Another possible application is the valve trains of heavy-duty internal combustion engines, whereby this refers to machines such as those used to power trucks, vans, light transporters, agricultural equipment, ships, mining or construction equipment, etc. It is also clear that the through hole in the valve body can also be arranged in a slightly "lowered" position than its highest possible.

[0008] According to a particularly preferred development, the housing is to be freely guided axially in the rocker arm mount without the usual retaining rings. The annular grooves / stop shoulders previously used for this purpose can be retained if necessary, thus eliminating the need for redesign. Alternatively, the outer shell of the housing and the rocker arm mount can now also be completely smooth-cylindrical in their surrounding area, thus eliminating annular grooves.

[0009] A practical solution involves designing the closure body as a cap, which is firmly attached to the inner casing of the housing via its annular collar. Such a closure body can be easily and securely attached without jamming. Alternatively, a disc is also being considered. The cap is inserted into the housing with its base facing forward, enclosing a hydraulic fluid chamber in front of the "high" through-hole.

[0010] While the piston's recess for the pin can be a radial bore, it is more practical to design it as a simple pocket in the piston's annular face.

[0011] The latter piston can be positioned directly at the base of the housing via its annular face. Alternatively, a conventional spacer disk can be applied, which has circumferentially distributed radial grooves for the hydraulic fluid to flow into the interior of the cap.

[0012] About the drawing: • Fig. 1 shows a partial view of a rocker arm in longitudinal section and • Fig. 2 shows the plug-in element of the rocker arm in an enlarged view.

[0013] Shown is a rocker arm 1 for a valve train of an internal combustion engine. As can be seen, a longitudinal plane of the rocker arm 1 runs vertically or approximately vertically, whereby an angle of up to 45° with the vertical may also be included.

[0014] The rocker arm 1 has a hydraulic insert element 4 (hydraulic lash adjuster) located in a receptacle 2 on its valve-side longitudinal side 3, comprising a piston 5 and a housing 6. An inner casing 7 of the piston 5 encloses a reservoir 8 for hydraulic fluid. The piston 5 rests above its annular face 9 on a spacer disk 27, which in turn rests on a base 10 of the receptacle 2.

[0015] The latter piston 5 is telescopically assembled with the housing 6. The housing 6 encloses the piston 5 with its bore 11 and is guided axially movably via its smooth cylindrical outer casing 12 in the likewise smooth cylindrical receptacle 2 of the rocker arm 1. The housing 6 has a contact foot 13 designed as an elephant foot joint and is located according to Fig. 1 in contact with a valve bridge as a follower 29. The rocker arm 1 mounted on an axis 32 is actuated at least indirectly by a lifting cam / lifting cam package, not shown.

[0016] How best to Fig. 2, a high-pressure chamber 16 for hydraulic fluid is formed between a valve-side web 14 of the piston 5 and a bottom 15 of the housing 6. A check valve 17 is arranged on the web 14, via which the high-pressure chamber 16 can be supplied with hydraulic fluid from the reservoir 8.

[0017] On the inner surface 7 of the piston 5, directly at its annular face 9, a separate closure body 18, present as a cap, is pressed over its annular collar 25. A bottom 26 of the closure body 18 is aligned on the valve side so that hydraulic fluid can be accumulated axially between it and the spacer disc 27.

[0018] The closure body 18 has an off-axis through-bore 20 located directly in front of its outer edge 19, which is located "at the top" in the vertical installation shown here. To prevent rotation and thus secure the upper position of the through-bore 20, a separate pin 21 engages in the piston 5. The pin 21 is seated at one end in a bore 23 extending from an end face 22 of the rocker arm 1 and intersecting its receptacle 2. At the other end, the pin 21 engages in a recess 24 formed as a pocket in the annular face 9 of the piston 5.

[0019] The Fig.The horizontal line drawn in Figure 2 above a central passage 31 in the web 14 of the piston 5 at the check valve 17 represents the column of hydraulic fluid, which is securely held in the reservoir 8 of the piston 5, even after the internal combustion engine has been idle for a long time, by the leakage prevention measures described here. The hydraulic fluid is not lower than a lower edge of the offset / top passage bore 20 in the closure body 18. This effectively prevents unwanted re-suction of air into the high-pressure chamber 16 of the piston 5, with its known disadvantages, particularly after re-ignition of the internal combustion engine. List of reference numbers 1 rocker arm 2 recording 3 long side 4 Insert element 5 pistons 6 housings 7 inner jacket 8 Storage room 9 Ring forehead 10 Reason 11 Hole 12 Outer jacket 13 Contact foot 14 jetty 15 Floor 16 High-pressure room 17 Check valve 18 locking bodies 19 Outer edge 20 through hole 21 pen 22 End forehead 23 Hole 24 recess 25 ring collars 26 Floor 27 spacer 28 inner forehead 29 follower 30 Longitudinal channel 31 Passage 32 Axis QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] DE 10 2021 114 644 A1

[0002]

Claims

[1] Rocker arm (1) for a valve train of an internal combustion engine, which rocker arm (1) is provided for vertical installation, comprising a hydraulic plug-in element (4) which is seated in a receptacle (2) on the valve-side longitudinal side (3) of the receptacle (2), with a piston (5) and a housing (6), wherein the piston (5), which encloses a storage chamber (8) for hydraulic medium via its inner jacket (7), rests at least indirectly on a base (10) of the receptacle (2) via its annular end (9), and the housing (6), which encloses the piston (5) with its bore (11), extends axially movable in the receptacle (2) via its outer jacket (12) and has a valve-side contact foot (13) for a follower element (29), wherein between a valve-side web (14) of the piston (5) and a bottom (15) of the housing (6), a high-pressure chamber (16) for hydraulic medium is formed, which is connected to the receptacle (2) via a Check valve (17) can be supplied with hydraulic fluid,wherein means for preventing leakage of the storage chamber (8) are provided, such that a separate disc-like closure body (18) is firmly seated on the inner casing (7) of the piston (5), directly at its annular end face (9), which closure body has a through-bore (20) arranged immediately in front of its outer edge (19), which in the case of vertical installation lies at a geodetically highest point, and wherein a separate pin (21) is provided for securing the piston (5) against rotation relative to the receptacle (2), which pin is seated at one end in a bore (23) extending from an end face (22) of the rocker arm (1) and intersecting its receptacle (2), and at the other end engages in a recess (24) of the piston (5) at its annular end face (9). [2] Rocker arm according to claim 1, wherein the closure body (18) is a cap which, via its annular collar (25), rests firmly on the inner jacket (7) of the piston (5) and whose indented bottom (26) is on the valve side. [3] Rocker arm according to claim 1 or 2, wherein the closure body (18) is pressed with the inner jacket (7) of the piston (5). [4] Rocker arm according to claim 1, wherein the recess (24) of the piston (5) for the pin (21) is present as a pocket in its annular end (9). [5] Rocker arm according to claim 1, wherein a spacer disc (27) is arranged on the base (10) of the receptacle (2) of the rocker arm (1), against the inner end face (28) of which the piston (5) rests directly. [6] Rocker arm according to claim 1, wherein the housing (6) is guided in the receptacle (2) of the rocker arm (1) without a retaining ring. [7] Rocker arm according to claim 1 or 6, wherein the outer casing (12) of the housing (6) and the receptacle (2) of the rocker arm (1) are continuously smooth-cylindrical in their surrounding area.

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