Claims
- 1. A valve drive device of an internal combustion engine, comprising a switching mechanism incorporated in a support element for support of a cam follower disposed in driving relationship between a camshaft and a gas exchange valve for switching the gas exchange valve to different valve lift curves in response to an operation of a cam arrangement, said support element including:
- a hollow cylindrical housing including an axis and received within an enveloping outer casing;
- an inner element axially displaceable relative to the housing and so received within the housing as to form at their interface an annular gap;
- and said switching mechanism including
- coupling means movable in a radial direction of said housing in a first radial bore arrangement so as to couple the inner element with the housing during a base circle phase of the cam arrangement by bridging the annular gap to thereby maintain a contact of the cam follower upon the cam arrangement, said coupling means being movable in the radial direction of said housing in a second bore arrangement which is spaced from the first radial bore arrangement in a direction of the axis so as to effect a disengagement of the cam follower from the cam arrangement in a phase of maximum cam lift.
- 2. The device of claim 1 wherein the coupling means includes a coupling element in the form of a piston displaceably received in the first radial bore arrangement comprised of one bore formed in the housing and another bore formed in the inner element, said bores of the first bore arrangement being aligned in the base circle phase of the cam arrangement for allowing the coupling element to bridge the annular gap, thereby coupling the housing and the inner element to one another, wherein the housing or the inner element has formed therein the second bore arrangement for engagement of the coupling element in the phase of maximum cam lift to thereby bridge the annular gap between the housing and the inner element for uncoupling of the cam follower from the cam arrangement.
- 3. The device of claim 2 wherein the cam follower is a finger lever.
- 4. The device of claim 2 wherein the coupling means includes a compression spring for loading the coupling element to move radially outwards for seeking a position in which the cam follower is disengaged from the cam arrangement, and further comprising hydraulic force-transmitting means acting in opposition to the spring for displacing the coupling element in a radially inward direction by a hydraulic medium to re-establish a contact between the cam follower and the cam arrangement during a closing phase of the gas exchange valve between a maximum valve lift and a minimum valve lift.
- 5. The device of claim 4 wherein the hydraulic force-transmitting means includes a supply duct formed in the outer casing and communicating with a longitudinally extending annular gap which, at least partially, surrounds an outer peripheral surface of the housing for permitting hydraulic medium to urge the coupling element in a radially inward direction.
- 6. The device of claim 2 wherein the second bore arrangement exhibits a bevel for engagement by the piston to effect an additional travel of the housing in a cam-distal direction when the cam follower is uncoupled from the cam arrangement.
- 7. The device of claim 2 wherein the cam follower is a finger lever, and further comprising a clasp-like connection for linking the housing in driving relationship to the finger lever.
- 8. The device of claim 1 wherein the support element includes a hydraulic clearance compensation unit.
- 9. The device of claim 1 wherein at least one component selected from the group consisting of the housing and the inner element is made of a light weight or polymeric material.
- 10. The device of claim 1 wherein the coupling means includes a first coupling element in the form of a piston displaceably received in the first radial bore arrangement comprised of one bore formed in the housing and another bore formed in the inner element, said bores of the first bore arrangement being aligned in a base circle phase of a cam arrangement of the camshaft for allowing the first coupling element to bridge the annular gap for coupling the housing and the inner element to one another, and a second coupling element so displaceably received in the second bore arrangement formed in the outer casing or the housing as to bridge an annular gap between the housing and the outer casing in a phase of maximum cam lift for uncoupling the cam follower from the cam arrangement.
- 11. The device of claim 10 wherein the outer casing is formed with a supply duct to convey a hydraulic medium to radial channels formed in the housing and the inner element and aligned at least in the base circle phase of the cam arrangement for forcing the first and second coupling elements in a radially outward direction.
- 12. The device of claim 10 wherein the outer casing is formed with a first supply duct to convey a hydraulic medium to radial channels formed in the housing and the inner element and aligned at least in the base circle phase of the cam arrangement for forcing the first coupling element in a radially outward direction, said housing having formed therein a second supply duct communicating with the second bore for conveying hydraulic medium to act upon the second coupling element, said second supply duct extending at a slight inclination with respect to a central longitudinal plane of the support element and being connected, at least in the phase of maximum cam lift, with the first supply duct.
- 13. The device of claim 10 wherein the second bore arrangement exhibits a bevel for engagement by the second coupling element to effect an additional travel of the housing in a cam-distal direction upon disconnection of the cam follower from the cam arrangement.
- 14. The device of claim 10 wherein the cam follower is a finger lever, and further comprising a clasp-like connection for linking the housing in driving relationship to the finger lever.
- 15. The device of claim 10 wherein the support element includes a hydraulic clearance compensation unit.
- 16. The device of claim 10 wherein at least one component selected from the group consisting of housing and inner element is made of a light-weight or polymeric material.
Priority Claims (1)
Number |
Date |
Country |
Kind |
44 04 145.4 |
Feb 1994 |
DEX |
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CROSS-REFERENCES TO RELATED APPLICATIONS
This application is a division of prior filed copending application Ser. No. 08/682,639, filed as PCT/DE95/00088 Jan. 26, 1995.
US Referenced Citations (14)
Foreign Referenced Citations (7)
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A 42 10 567 |
Oct 1992 |
DEX |
93 06 685 |
Jun 1993 |
DEX |
U 93 19 435 |
Feb 1994 |
DEX |
A 43 14 619 |
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DEX |
60-1 11 009 |
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JPX |
61-2 01 807 |
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JPX |
A 2 268 242 |
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GBX |
Divisions (1)
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Number |
Date |
Country |
Parent |
682639 |
Oct 1996 |
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