EP0343931A1
Expired / Lapsed
EP
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Mechanism for switching valve operation modes in an internal combustion engine
Assignee: Honda Motor Co Ltd
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Filing: 1989-05-23
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Granted: —
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Expires: 2009-05-23
Abstract
Abstract A mechanism for switching valve operation modes in an internal combustion engine has a valve operating mechanism with a high- (4) and low-speed cams (3a,3b) having different cam profiles corresponding to rotational speed ranges of the engine, a pair of valves disposed in intake or exhaust ports of a combustion chamber and normally urged to be closed by spring means, a pair of directly moving rocker arms (5,7) for imparting the list of the low-speed cams to the valves, an idling rocker arm (6) for transmitting the lift of said high-speed cam (4) to the pair of valves and a selective coupling mechanism (14) for selectively connecting the rocker arms when mutually adjacent portions of the rocker arms are in a predetermined positional relationship. The diameter (D2) of the base-circle portion of the high-speed cam (4) is smaller than the diameter (D1) of the base-circle portion of the low-speed cam (3a,3b) whereby the selective coupling mechanism may be readily operated to connect the rocker arms without compressing the valve springs.
Inventors
- 👤 Koichi Fukuo
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 06:23
CPC Classifications
F; F01; F01L; F01L1/00; F01L1/26; F01L1/267
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
132 words
A mechanism for switching valve operation modes in an internal combustion engine having high- and low-speed cams with different cam profiles corresponding to rotational speed ranges of the engine, a valve disposed in an intake or exhaust port of a combustion chamber and normally urged to be closed by spring means, a directly moving transmitting member for imparting a lift of said low-speed cam to said valve, an idling transmitting member for transmitting a lift of said high-speed cam to said valve, and selective coupling means for selectively connecting said transmitting members when mutually adjacent portions of the transmitting members are in a predetermined positional relationship, characterised in that the diameter of a base-circle portion of said high-speed cam is smaller than the diameter of a base-circle portion of said low-speed cam.
Claim 2
Dependent Claim
132 words
A mechanism for switching valve operation modes in an internal combustion engine having high- and low-speed cams with different cam profiles corresponding to rotational speed ranges of the engine, a valve disposed in an intake or exhaust port of a combustion chamber and normally urged to be closed by spring means, a directly moving transmitting member for imparting a lift of said low-speed cam to said valve, an idling transmitting member for transmitting a lift of said high-speed cam to said valve, and selective coupling means for selectively connecting said transmitting members when mutually adjacent portions of the transmitting members are in a predetermined positional relationship, characterised in that the diameter of a base-circle portion of said high-speed cam is smaller than the diameter of a base-circle portion of said low-speed cam.
Claim 3
Dependent Claim
57 words
A mechanism according to claim 1, wherein said selective coupling means comprises an engaging portion defined on an axis extending across said transmitting members, and a coupling member fittable into said engaging portion, at least one of an inlet opening of said engaging portion and an entering end of said coupling member having a tapered beveled surface.
Claim 4
Dependent Claim
18 words
A mechanism according to claim 2, wherein each inlet opening and entering end has a tapered, beveled surface.
Claim 5
Dependent Claim
63 words
A mechanism according to claim 1, wherein urging means are provided for continuous urging said idling transmitting means against said high-speed cam, said urging means including means for imposing a small urging force when said idling transmitting means engages said base-circle portion of said high-speed cam and a larger urging force when said transmitting means engages any other portion of said high-speed cam.
Claim 6
Dependent Claim
182 words
A mechanism for switching valve operation modes in an internal combustion engine, having high- and low-speed cams with different cam profiles corresponding to rotational speed ranges of the engine and having base-circle portions, a valve disposed in an intake or exhaust port of a combustion chamber, a directly moving transmitting means engaging said low-speed cam for imparting a lift of said low-speed cam to said valve, an idling transmitting means engaging said high-speed cam for transmitting a lift of said high-speed cam to said valve, and selective coupling means for selectively connecting said transmitting means when mutually adjacent portions of the transmitting means are in a predetermined positional relationship, said transmitting means having an ideal position of positional relationship wherein the selective coupling means are aligned for ready selective connecting, characterized in that said transmitting means and said cam have predetermined dimensions for causing said idling transmitting means to be offset by a small amount from said ideal position in the direction of closing the valve when the directly moving and idling transmitting means are disconnected and engaging the cam base-circle portions.
Claim 7
Dependent Claim
182 words
A mechanism for switching valve operation modes in an internal combustion engine, having high- and low-speed cams with different cam profiles corresponding to rotational speed ranges of the engine and having base-circle portions, a valve disposed in an intake or exhaust port of a combustion chamber, a directly moving transmitting means engaging said low-speed cam for imparting a lift of said low-speed cam to said valve, an idling transmitting means engaging said high-speed cam for transmitting a lift of said high-speed cam to said valve, and selective coupling means for selectively connecting said transmitting means when mutually adjacent portions of the transmitting means are in a predetermined positional relationship, said transmitting means having an ideal position of positional relationship wherein the selective coupling means are aligned for ready selective connecting, characterized in that said transmitting means and said cam have predetermined dimensions for causing said idling transmitting means to be offset by a small amount from said ideal position in the direction of closing the valve when the directly moving and idling transmitting means are disconnected and engaging the cam base-circle portions.
Claim 8
Dependent Claim
57 words
A mechanism according to claim 5, wherein said selective coupling means comprises an engaging portion defined on an axis extending across said transmitting means, and a coupling member fittable into said engaging portion, at least one of an inlet opening of said engaging portion and an entering end of said coupling member having a tapered beveled surface.
Claim 9
Dependent Claim
19 words
A mechanism according to claim 6 wherein said axes of said transmitting means are aligned in said ideal position.
Claim 10
Dependent Claim
72 words
A mechanism according to claim 5 wherein said selective coupling means include a piston slidably mounted in a guide hole in a transmitting means and movable into a guide hole in an adjacent transmitting means for coupling said transmitting means, said guide holes each having an axis, said guide hole axes being aligned in said ideal position and offset in the position of the transmitting means, each engaging a cam base-circle portion.
Claim 11
Dependent Claim
59 words
A mechanism according to any of claims 5 to 8 wherein urging means are provided for continuously urging said idling transmitting means into engagement with said high-speed cam, said urging means including means for imposing a substantially lower urging force when said idling transmitting means engages said base-circle portion than when it engages a lobe of the high-speed cam.
References Cited (Backward Citations)
EP0264253A1
Cited
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