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

The invention concerns a switchable support element for a valve train of an internal combustion engine, said support element comprising a housing in whose bore an axially displaceable inner element comprising a head for mounting a finger lever is received, a coupling means extending in the inner element can be brought partially into engagement with an entraining surface of the housing for achieving coupling [axially distant position of the inner element relative to the housing], a lost motion spring means being arranged for acting between the inner element and the housing, and said support element further comprising at least one vertical stop means that overlaps an annular groove between the inner element and the housing for defining a coupling position of said coupling means with coupling lash relative to said entraining surface.

Support elements of the pre-cited type are well known in the technical field. The vertical stop means is constituted, for example, by transversely extending pins that are fixed in a reception of one of the components (housing or inner element) and project into a corresponding groove on the respective other component. For instance, these pins are pressed into said reception. To a person skilled in the art, it is clear that this interference can come loose during the operation of the valve train. In addition, pressing-in introduces an undesired force into the surrounding material. Further, the pins cannot be removed if disassembly is required (selective pairing of thickness-grouped pins for adjusting coupling lash . . . ).

In other solutions known from older prior art, a bore-distal front end of the housing comprises a radially inward bent-over collar against which the inner element abuts through a respective counter surface. This collar proves to be relatively complex from the manufacturing point of view, especially because it likewise does not enable an appropriate adjustment of a coupling lash.

In still other prior art solutions, the vertical stop means is constituted by one or two locking rings/snap rings that extend in a groove of one of the components and, in case of abutment, function as a stop in cooperation with a corresponding edge of the respective other component. It is noted in this connection that handling of these snap rings is relatively difficult in practice.

The object of the invention is therefore to provide a switchable support element of the pre-cited type in which the aforesaid drawbacks are eliminated.

This object is achieved according to the invention by the fact that the vertical stop means is constituted by at least one thin-walled ring comprising a slot, the ring is placed or slipped axially, slot ahead, onto an outer peripheral surface of the housing to extend parallel a transverse plane of the support element, the housing comprises at least one aperture through which a corresponding inner peripheral segment of the ring extends, a longitudinal or annular grove extends in the outer peripheral surface of the inner element, into which groove the inner peripheral segment projects, and an underside of the inner peripheral segment comes to abut against a lower end of said groove for defining the coupling position.

In this way, a switchable support element is obtained in which the aforesaid drawbacks are effectively eliminated in a simple manner. The thin-walled, U-shaped ring constituting the vertical stop means is available, for example, as an extremely cheap mass article.

After pre-assembly of the switchable support element, the ring can be slipped onto the outer peripheral surface of the housing in a simple manner, with the slot ahead, preferably but not exclusively in parallel orientation to a transverse plane of the support element. According to a further development of the invention, for its axial fixing, the ring can be made to extend in a corresponding annular groove in the outer peripheral surface of the housing.

According to another provision of the invention, the outer peripheral surface of the housing comprises at least one slot (but preferably, two slots situated diametrically opposite each other), into which slot the ring, as a vertical stop means, projects with a respective inner peripheral segment. Thus, this inner peripheral segment extends radially inwards partially beyond the bore of the housing.

As a counter surface for the inner peripheral segment of the ring, a flattened longitudinal groove is arranged, for instance, on the corresponding inner peripheral segment-side of the outer peripheral surface of the inner element. An important feature of the invention is that a lower end of the longitudinal groove of the inner element serves as a stop surface for an underside of the inner peripheral segment for defining the coupling position.

Using off-the-shelf rings sorted in height groups as vertical stops, the coupling lash can be adjusted in a manner, known per se. By coupling lash (whose variation should be kept as constantly low as possible over a large series of elements) is to be understood the idle displacement of the inner element with extended coupling elements towards the housing into the stop position of the inner element on the ring when the coupling element comes to abut against the respective entraining surface of the housing.

The aforesaid ring constituting the vertical stop means may be made of spring steel or the like. However, it is also conceivable to configure it out of a light weight material like plastic.

According to a particularly advantageous development of the invention, the ring constituting the vertical stop acts at the same time as an anti-rotation device between the inner element and the housing. For this purpose, an inner peripheral surface of the inner peripheral segment of the ring can be configured as a chord-shaped key surface that directly adjoins the longitudinal groove in the inner element configured as a complementary, longitudinal flattened portion. It is clear to a person skilled in the art that preferably two opposing key surfaces will be used, but their number may also differ from this.

According to another provision of the invention, an upper end of the longitudinal or annular groove in the outer peripheral surface of the inner element is configured as a stop surface for defining a retracted position of the inner element. In this way, it can be avoided, for instance, that the lost motion spring (preferably a coiled compression spring or a coiled compression spring assembly) reaches it block position.

It is emphasized that the aforesaid measures like upper vertical stop, lower vertical stop and anti-rotation device may also be provided singly or in combination with only one of the other measures.

The aperture or apertures in the outer periphery of the housing can be generated, for example, with the help of a simple disk milling cutter.

Finally, according to another feature of the invention, the coupling means is at least one piston that extends in a radial bore of the inner element and can be displaced for achieving coupling into or under the entraining surface. Preferably, two coupling pistons situated diametrically opposite each other in the inner element are used. A coupling surface in the housing can be constituted, for example, by an annular groove, an annular groove segment, an aperture, an underside of a projection etc.

The invention is described more closely in the following with reference to the appended drawing.

FIGS. 1 , 2 each show longitudinal sections through the support element of the invention, offset by 90° from one another, and

FIG. 3 shows a ring constituting a vertical stop means.

FIGS. 1 and 2 disclose a switchable support element 1 . This support element 1 comprises a pot-shaped housing 2 that is closed by a bottom 24 . An inner element 4 extends within a bore 3 of the housing for axial displacement relative to the housing 2 . The inner element 4 comprises a hydraulic lash adjuster, not needing specific description here, and a head 5 of the inner element projects out of the housing 2 . A lost motion spring means 8 (coiled compression spring assembly) is installed between an underside 23 of the inner element 4 and the bottom 24 .

Directly above its underside 23 , the inner element 4 comprises a coupling means ( 6 ) in the form of two pistons situated diametrically opposite each other in a bore. These pistons can be displaced radially outwards by compression spring force into their coupling position illustrated in FIG. 2 . In the coupled state, these pistons project into a corresponding aperture serving as an entraining surface 7 in the housing 2 .

As best seen in FIG. 2 , a thin-walled ring comprising a slot 11 and forming a vertical stop means 10 is arranged in an annular groove 22 in the outer peripheral surface 12 of the housing 2 . For assembly, this ring is “slipped-on” in parallel orientation to a transverse plane of the support element 1 . Two diametrically opposed inner peripheral segments 14 of said ring project through corresponding apertures 13 of the housing 2 so as to extend radially inside, for example, in a longitudinal groove 16 in the outer peripheral surface 15 of the inner element 4 , so that they are seated with their inner peripheral surface 19 , configured as a chord-shaped key surface, directly in front of the respective longitudinal groove 16 of the inner element 4 .

FIG. 2 illustrates the end stop state of the inner element 4 with the lower end 17 of the longitudinal groove 16 bearing against an underside 18 of the inner peripheral segment 14 of the ring. Thus a coupled position, not needing further specification, with coupling lash of the coupling means 6 relative to the entraining surface 7 in the housing 2 is created.

At the same time, a simple anti-rotation device of the inner element 4 relative to the housing 2 is obtained through the aforesaid chord-like key surfaces of the inner peripheral surface 19 of the inner peripheral segments 14 of the ring that cooperate with the longitudinal groove 16 of the inner element 4 , so that the coupling means 6 is oriented in peripheral direction with respect to its entraining surface 7 . If the entraining surface 7 is configured as an annular groove, this anti-rotation device may be omitted, if appropriate.

Further, an upper end 21 of the longitudinal or annular groove 16 in the outer peripheral surface 15 of the inner element 4 can be used to define a retracted position of the inner element in the housing 2 . To define the retracted position, the upper end 21 of the longitudinal or annular groove 16 of the inner element 4 comes to abut against an upper side 20 of the inner peripheral segment 14 of the ring constituting the vertical stop means 10 (for uncoupling). This prevents a block position of the lost motion spring 8 .

During assembly, the outer peripheral surface of the ring constituting the vertical stop means 10 can, but does not have to, project beyond the outer peripheral surface 12 of the housing 2 .

1 Support element

2 Housing

3 Bore

4 Inner element

5 Head

6 Coupling means

7 Entraining surface

8 Spring means

9 Annular gap

10 Vertical stop means

11 Slot

12 Outer peripheral surface

13 Aperture

14 Inner peripheral segment

15 Outer peripheral surface

16 Longitudinal or annular groove

17 Lower end

18 Underside

19 Inner peripheral surface

20 Upper side

21 Uppers

22 Annular groove

23 Underside

24 Bottom