Switchable support element for a valve train of an internal combustion engine

Abstract

Switchable support element (1) for a valve train of an internal combustion engine, comprising a thin-walled, tubular or pot-shaped housing (2) which can be fixedly arranged in a receptacle of the internal combustion engine via its outer shell (3), wherein an axially movable pressure piston (5) which is provided with an anti-rotation device (17) runs in a bore (4) of the housing (2), the head (7) of which serves as a bearing for a rocker arm projects beyond an edge (8) of the housing (2) and is acted upon from the housing (2) by a helical compression spring (6) which is located axially below the pressure piston (5) in a spring chamber (25) and acts at one end against a base (23) of the housing (2) farther from the edge and at the other end against an underside (24) of the pressure piston (5), wherein two Coupling pistons (10) are diametrically opposed, which,Starting from their respective outer faces (12), on the underside (13) of which they have a section-wise flattening (14), wherein a compression spring (19) is located centrally in the through-bore (9) and acts with one end against the inner faces (20) of the coupling pistons (10), by means of which the coupling pistons (10), which are provided with an anti-rotation device (18) relative to their through-bore (9), can be displaced radially outwards with their respective flattening (14) onto a drive surface (11) of the housing (2) in the case of coupling, which drive surface (11) is the underside (15) of a window-like, punched opening (16) of the bore (4) of the housing (2), which opening (16) extends only as a section on the side of the respective coupling piston (10), wherein, in the case of decoupling, the coupling pistons (10) are displaced radially inwards into the through-bore (9) the pressure piston (5) can be restored via hydraulic means,which is guided into an annular groove (21) in the outer shell (3) of the housing (2) in front of its outer faces (12) and wherein the pressure piston (5) experiences a height stop from the housing (2) via a stack of two superimposed ring parts (32) which sit near the edge (8) of the housing (2) in its bore (4) and on whose underside (33) the pressure piston (5) abuts with a shoulder (34), at which stop an extension of the coupling pistons (10) in the coupling direction is enabled.

Description

[0001] The invention relates to a switchable support element for a valve train of an internal combustion engine, comprising a thin-walled, tubular or pot-shaped housing which can be fixedly arranged in a receptacle of the internal combustion engine via its outer shell, wherein an axially movable pressure piston, equipped with an anti-rotation device, runs in a bore of the housing, the head of which serves as a bearing for a rocker arm, projects beyond an edge of the housing and is acted upon from within the housing by a helical compression spring, wherein in a radial through-bore of the pressure piston, which runs along its underside furthest from the head, two coupling pistons are diametrically opposed to each other, which, starting from their respective outer faces, have a section-wise flattening on their underside, wherein a compression spring is located centrally in the through-bore, acting with one end against the inner faces of the coupling pistons.via which the coupling pistons, which are provided with an anti-rotation device relative to their through-bore, can be displaced radially outwards with their respective flattening onto a drive surface of the housing for a coupling case, and wherein, for a decoupling case, a displacement of the coupling pistons radially inwards back into the through-bore of the pressure piston can be effected by means of hydraulic fluid which is directed in front of the outer faces of the coupling pistons.

[0002] A switchable support element goes out Fig. 2 of DE 601 11 117 T2. The housing has an annular groove in its bore, to be installed from the bore side, for engagement of the two stepped coupling pistons in the coupling case. Hydraulic fluid is supplied for the decoupling case via radial bores in the housing, which are aligned upstream of the two coupling pistons (sa Fig. 4, Fig. 5) It can also be seen that the helical compression spring is arranged radially in an annular space of the support element between the housing and the pressure piston and is clamped at both ends by separate stop rings. The lower of the stop rings provides a guide for the pressure piston in its extension direction.

[0003] DE 102 45 301 A1 discloses an oscillating roller tappet of switchable type for a pushrod valve train. The roller tappet has two opposing coupling pistons in the pressure piston, which are in turn flattened. An annular groove is machined into the bore of the housing, into which the coupling pistons move when coupled. The housing has two radial bores to guide the hydraulic fluid into the annular groove.

[0004] German patent DE 42 06 166 A1 discloses a switchable tappet which is arranged between a cam assembly and a gas exchange valve. Its outer part has circumferentially distributed slides with radially internal pins which, in the case of coupling, engage in an annular groove on the outer surface of the inner part of the tappet.

[0005] A cup or roller tappet with coupling slides that can be displaced radially inwards can be found in US Patent 5,253,621 A. Fig. 10 (roller tappets) are located in the housing, with two double-stepped coupling pistons on the inner end face for their radial inward displacement. The inner element has, opposite the coupling pistons, two bowstring-like milled recesses on its outer surface for engagement of the coupling pistons.

[0006] WO 94 / 21 899 A1 discloses a tappet in whose housing three circumferentially distributed coupling pistons are located radially inwards for coupling engagement.

[0007] A coupling of a single cylindrical coupling piston into a complementary bore of a housing of a switchable support element is known from the publications DE 101 22 373 A1 and DE 100 55 014 A1.

[0008] The task is to create a simply constructed, switchable support element that has a coupling mechanism that is easy to manufacture and simple to actuate.

[0009] According to the invention, this problem is solved by the new features of claim 1.Accordingly, the drive surface for the coupling pistons in the housing is designed as the underside of a window-like, stamped opening in the housing bore, which is only present in the section of the coupling pistons, wherein the helical compression spring for resetting the pressure piston sits axially below it in a spring chamber and acts at one end against a base of the housing far from the edge and at the other end against an underside of the pressure piston, wherein an annular groove is provided in the outer shell of the housing to guide the hydraulic fluid in front of the outer faces of the coupling pistons, and wherein the pressure piston experiences a height stop from the housing via a stack of two superimposed ring parts, which sit near an edge of the housing in its bore and against the underside of which the pressure piston abuts with a shoulder, at which stop extension of the coupling pistons in the coupling direction is enabled.

[0010] Thus, a simple engagement of the coupling pistons is achieved through a simple, window-like opening in the housing. Due to the two coupling pistons being diametrically opposed within the inner element, the surface pressure is relatively low when coupled. Instead of a single through-hole in the inner element, a blind hole can also be provided for each coupling piston. A helical compression spring assembly is also considered as an alternative to the simple helical compression spring in the inner element in front of the coupling pistons.

[0011] Simultaneously, simple height stop devices for the pressure piston are provided in the form of two stacked retaining rings at the upper edge of the housing. When the pressure piston abuts the underside of the lower retaining ring, the coupling pistons can extend into the window-like opening. It is clear that the use of height-grouped retaining rings can also be used to adjust the coupling play. More precisely, at least one of the two rings is grouped by thickness.

[0012] The simultaneously proposed annular groove for the hydraulic fluid in the outer shell of the housing in front of the coupling piston allows for the elimination of a rotation lock for the entire support element relative to its mounting in the housing.

[0013] Furthermore, the helical compression spring acting on the pressure piston, also known as a "lost-motion spring," should be located in a spring chamber between the base of the housing and the underside of the pressure piston. A helical compression spring assembly is also conceivable here.

[0014] For example, a simple anti-rotation device for the pressure piston relative to the housing could be an element applied between the two components, such as a ball, a needle, a spring-groove connection, but also flattening or the like.

[0015] According to an advantageous embodiment of the invention, a transverse opening leads from the aforementioned spring chamber at least indirectly to the outside, such that air is not unnecessarily compressed during the immersion movement of the pressure piston in the case of decoupling.

[0016] The thin-walled housing is lightweight and can be manufactured, for example, using a deep-drawing or flow-forming process.

[0017] The invention is explained in more detail with reference to the drawing. The drawing shows: Fig. 1, Fig. 2 longitudinal sections, each offset by 90° from each other, through a support element and the Fig. 3 a cross-section through the support element in the area of ​​its coupling pistons.

[0018] The illustration shows a switchable support element 1 for a valve train of an internal combustion engine. This element has a hollow cylindrical housing 2 in whose bore 4 an axially movable pressure piston 5 is arranged. The support element 1 can be permanently installed in a mounting of an internal combustion engine via an outer shell 3 of the housing 2.

[0019] A stack of two helical compression springs 6 runs between a bottom surface 24 of the pressure piston 5 and a base 23 of the housing 2. Furthermore, the pressure piston 5 has a head 7, which here forms part of an internal element 31 of a hydraulic backlash compensation device 30 and on which a lever-like cam follower, such as a rocker arm, can be supported at one end. Optionally, a rocker arm bearing can also be provided, or alternatively, the support element 1 can be used as an actuating element in a switchable lever valve train.

[0020] In a lower area, the pressure piston 5 has a through-bore 9. In this bore, two diametrically opposed coupling pistons 10 are located in the case of decoupling. These can be acted upon radially outwards by the force of a centrally arranged compression spring 19, which acts against the inner faces 20 of the coupling pistons 10.

[0021] The through-bore 9 is cut centrally and axially downwards by a radial pin 18, which has a through-channel 27. The through-channel 27 serves to drain air and hydraulic fluid into a spring chamber 25. From the spring chamber 25, air and, if applicable, hydraulic fluid contained therein can be discharged to the outside via a transverse opening 26.

[0022] At the same time, the radial pin 18 serves as a radially internal stop for the coupling pistons 10 and as a means of preventing them from rotating. For this purpose, the coupling pistons 10 each have a longitudinal slot 22 on their inner faces 20, which, in the event of contact, partially engages the radial pin 18.

[0023] The coupling pistons 10 have a flattened section 14 on their respective undersides 13, extending from their outer faces 12. This flattened section allows them to be moved onto the underside 15 of a window-like opening 16 in the housing 2 when coupled. This opening 16 thus extends only as a section on the side of the respective coupling piston 10. It can be generated, for example, by punching or a simple parallel milling operation. The coupling pistons 10 are stopped in the coupling direction by their stepped sections 28 bearing against the bore 4 at the edge.

[0024] The coupling pistons 10 are displaced radially inwards by means of hydraulic fluid. This fluid can be directed into an annular groove 21 in the outer shell 3 of the housing 2, which annular groove 21 communicates with the respective opening 16.

[0025] Furthermore, it is from Fig.2 can be seen in more detail that an anti-rotation device 17 (here a ball) is installed in the bore 4 of the housing 2. This interacts with a counter-surface 29 (here a longitudinal slot) in the anti-rotation direction.

[0026] A height stop for the pressure piston 5 extending from the housing 2 is formed by a stack of ring parts 32. The pressure piston 5 abuts with its shoulder 34 against a bottom surface 33 of the stack of ring parts (here, two stacked on top of each other). Simultaneously, a coupling clearance can also be adjusted via the stack of ring parts 32, in which at least one of the two stacked ring parts is provided with a thickness grouping (see WO 2003 / 067 038 A1). List of reference figures 1 support element 2 cases 3 Outer jacket 4 holes (housing) 5 pressure pistons 6 helical compression springs 7 heads 8 rand 9 through holes 10 coupling pistons 11 Carrier area 12 Outer forehead 13 Underside 14 Flattening 15 Underside 16 Breakthrough 17 Anti-rotation device 18) Radial pin, anti-rotation device 19 Compression spring 20 Inner forehead 21 Ring groove 22 longitudinal slots 23 Base Case 24 Underside of pressure piston 25 spring space 26 Cross opening 27 Through channel 28-step range 29 Opposite surface 30 Game compensation device 31 Interior element 32 Height stop, ring part 33 Underside of ring part 34 Shoulder

Claims

[1] Switchable support element (1) for a valve train of an internal combustion engine, comprising a thin-walled, tubular or pot-shaped housing (2) which can be fixedly arranged in a receptacle of the internal combustion engine via its outer shell (3), wherein an axially movable pressure piston (5) which is provided with an anti-rotation device (17) runs in a bore (4) of the housing (2), the head (7) of which serves as a bearing for a rocker arm projects beyond an edge (8) of the housing (2) and is acted upon from the housing (2) by a helical compression spring (6) which is located axially below the pressure piston (5) in a spring chamber (25) and acts at one end against a base (23) of the housing (2) farther from the edge and at the other end against an underside (24) of the pressure piston (5), wherein a radial through-bore (9) of the pressure piston (5), which runs along its underside (24) farther from the head two coupling pistons (10) are diametrically opposed, which,Starting from their respective outer faces (12), on the underside (13) of which they have a section-wise flattening (14), wherein a compression spring (19) is located centrally in the through-bore (9) and acts with one end against the inner faces (20) of the coupling pistons (10), by means of which the coupling pistons (10), which are provided with an anti-rotation device (18) relative to their through-bore (9), can be displaced radially outwards with their respective flattening (14) onto a drive surface (11) of the housing (2) in the case of coupling, which drive surface (11) is the underside (15) of a window-like, punched opening (16) of the bore (4) of the housing (2), which opening (16) extends only as a section on the side of the respective coupling piston (10), wherein, in the case of decoupling, the coupling pistons (10) are displaced radially inwards into the through-bore (9) the pressure piston (5) can be restored via hydraulic means,which is guided into an annular groove (21) in the outer shell (3) of the housing (2) in front of its outer faces (12) and wherein the pressure piston (5) experiences a height stop from the housing (2) via a stack of two superimposed ring parts (32) which sit near the edge (8) of the housing (2) in its bore (4) and on whose underside (33) the pressure piston (5) abuts with a shoulder (34), at which stop an extension of the coupling pistons (10) in the coupling direction is enabled. [2] Support element according to claim 1, wherein the anti-rotation device (17) of the pressure piston (5) relative to the housing (2) is represented by an element such as a ball or a needle applied to one of the components (housing (2), pressure piston (5)) in the separation area to the respective other component (5, 2), which engages with a respective longitudinally extending counter surface (29) on the respective other component (5, 2), or that the anti-rotation device (17) of the pressure piston (5) relative to the housing (2) is represented by mutually engaging flats in the separation area between the components (2, 5). [3] Support element according to claim 1, wherein at least one transverse opening (26) leads away from the spring space (25) radially encompassed by the housing (2).

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