EP0384361A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Valve train for automotive engine
Assignee: Nissan Motor Co Ltd
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Filing: 1990-02-19
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Granted: —
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Expires: 2010-02-19
Abstract
Abstract In a valve train for an I.C. engine, a cam shaft (1) has cams (2, 3) formed with compound curvatures which allow the valve timing to be altered while the engine is operating, to suit the engine driving conditions by shifting the cam shaft (1) along its axis. To reduce the force necessary to shift the cam shaft along its axis the valve closure springs are replaced by closure cams (3). In some embodiments pivoting arrangements comprising a pair of ball (11) and socket joints (7) are provided to eliminate lateral sway of the rocker arms allowing precise adjustment of the valve timing when the cam shaft is shifted along its axis. In other embodiments the rocker arms are journalled on a rocker shaft provided with stops for preventing lateral sway. In some embodiments the closure rocker arms (15) have cupped ends in which either the valve stem retainer (17) or the valve stem seal is received.
Inventors
- 👤 Yutaka Matayoshi
- 👤 Shigeru Kamegaya
- 👤 Shigeru Sakuragi
- 👤 Hiroshi Komatsu
- 👤 Kozaburo Okawa
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 06:24
CPC Classifications
F; F01; F01L; F01L1/00; F01L1/30; F01L1/12; F01L1/18; F01L13/00; F01L13/0015; F01L13/0036; F01L13/0042; Y; Y10; Y10T; Y10T74/00; Y10T74/21; Y10T74/2101
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
198 words
A valve train for an internal combustion engine comprising: a cam shaft, said cam shaft being operatively connected with a crank shaft of said engine; an opening cam, said opening cam being formed so as to have a cam profile which varies along the axis of said cam shaft; a closure cam, said closure cam being formed so as to have a cam profile which varies along the axis of said cam shaft; axial driving means for driving said cam shaft along its axis; an opening rocker arm, said opening rocker arm having formed thereon a valve stem engaging portion for engaging a valve stem of a poppet valve and for exerting a force thereon in an opening direction; an opening cam follower, said opening cam follower being formed on said opening rocker arm for engagement with said opening cam; a closure rocker arm, said closure rocker arm having formed thereon a valve stem engaging portion for engaging a valve stem of a poppet valve and for exerting a force thereon in a valve closing direction; and a closure cam follower, said closure cam follower being formed on said closure rocker arm for engagement with said closure cam.
Claim 2
Dependent Claim
198 words
A valve train for an internal combustion engine comprising: a cam shaft, said cam shaft being operatively connected with a crank shaft of said engine; an opening cam, said opening cam being formed so as to have a cam profile which varies along the axis of said cam shaft; a closure cam, said closure cam being formed so as to have a cam profile which varies along the axis of said cam shaft; axial driving means for driving said cam shaft along its axis; an opening rocker arm, said opening rocker arm having formed thereon a valve stem engaging portion for engaging a valve stem of a poppet valve and for exerting a force thereon in an opening direction; an opening cam follower, said opening cam follower being formed on said opening rocker arm for engagement with said opening cam; a closure rocker arm, said closure rocker arm having formed thereon a valve stem engaging portion for engaging a valve stem of a poppet valve and for exerting a force thereon in a valve closing direction; and a closure cam follower, said closure cam follower being formed on said closure rocker arm for engagement with said closure cam.
Claim 3
Dependent Claim
27 words
A valve train for an internal combustion engine as set forth in claim 1 wherein said closure cam follower and said opening cam follower have convex crowns.
Claim 4
Dependent Claim
97 words
A valve train for an internal combustion engine as set forth in claim 1 wherein the profile of said closure cam is such that, when said valve stem is urged in the closing direction by the closure rocker arm in response to the rotation of said cam shaft, it moves in a manner which causes said valve stem to exert a force on said valve stem engaging portion of said opening rocker and causes said opening cam follower to be maintained in one of engagement and near engagement with a non-thrust face portion of said opening cam.
Claim 5
Dependent Claim
218 words
A valve train for an internal combustion engine comprising: a cam shaft, said cam shaft being operatively connected with a crank shaft of said engine; an opening cam; a closure cam; an opening rocker arm, said opening rocker arm having formed thereon a valve stem engaging portion for engaging a valve stem of a poppet valve and for exerting a force thereon in an opening direction; an opening cam follower, said opening cam follower being formed on said opening rocker arm for engagement with said opening cam; a closure rocker arm, said closure rocker arm having formed thereon a valve stem engaging portion for engaging a valve stem of a poppet valve and for exerting a force thereon in a valve closing direction, said closure rocker arm being pivotally mounted on said opening rocker arm so as to pivot with respect thereto along a first axis; a closure cam follower, said closure cam follower being formed on said closure rocker arm for engagement with said closure cam; and a pair of ball and socket pivots, said pair of ball and socket pivots pivotably coupling one of said opening and said closing rocker arms to an cylinder head and defining a second pivoting axis about which said one of said rocker arms pivots with respect to said cylinder head.
Claim 6
Dependent Claim
218 words
A valve train for an internal combustion engine comprising: a cam shaft, said cam shaft being operatively connected with a crank shaft of said engine; an opening cam; a closure cam; an opening rocker arm, said opening rocker arm having formed thereon a valve stem engaging portion for engaging a valve stem of a poppet valve and for exerting a force thereon in an opening direction; an opening cam follower, said opening cam follower being formed on said opening rocker arm for engagement with said opening cam; a closure rocker arm, said closure rocker arm having formed thereon a valve stem engaging portion for engaging a valve stem of a poppet valve and for exerting a force thereon in a valve closing direction, said closure rocker arm being pivotally mounted on said opening rocker arm so as to pivot with respect thereto along a first axis; a closure cam follower, said closure cam follower being formed on said closure rocker arm for engagement with said closure cam; and a pair of ball and socket pivots, said pair of ball and socket pivots pivotably coupling one of said opening and said closing rocker arms to an cylinder head and defining a second pivoting axis about which said one of said rocker arms pivots with respect to said cylinder head.
Claim 7
Dependent Claim
74 words
A closure rocker arm for an internal combustion engine comprising: a valve stem closure portion, said valve stem closure portion comprising a horizontally extending web portion; and a flange portion, said flange portion extending at a side of said horizontally extending web portion at substantially right angles thereto for stiffening said web portion, said web portion engaging a valve stem of a poppet valve for exerting a force thereon in a valve closing direction.
Claim 8
Dependent Claim
74 words
A closure rocker arm for an internal combustion engine comprising: a valve stem closure portion, said valve stem closure portion comprising a horizontally extending web portion; and a flange portion, said flange portion extending at a side of said horizontally extending web portion at substantially right angles thereto for stiffening said web portion, said web portion engaging a valve stem of a poppet valve for exerting a force thereon in a valve closing direction.
Claim 9
Dependent Claim
39 words
A closure rocker arm for an internal combustion engine as set forth in claim 5 wherein a pair of said flange portions extend at either side of said web portion and a valve stem retainer member is accommodated therebetween.
Claim 10
Dependent Claim
39 words
A closure rocker arm for an internal combustion engine as set forth in claim 5 wherein a pair of said flange portions extend at either side of said web portion and a valve stem seal member is accommodated therebetween.
Claim 11
Dependent Claim
65 words
An adjustable valve train for an internal combustion engine as set forth in claim 1 wherein one of said closure rocker arm and said opening rocker arm is pivotally connected to a cylinder head so as to pivot along a first axis and said closure rocker arm and said opening rocker arm are mutally pivotally connected so as to mutually pivotable along a second axis.
Claim 12
Dependent Claim
49 words
An adjustable valve train for an internal combustion engine as set forth in claim 8 wherein said first pivoting axis is defined to intersect a ball a socket joint by which one of said closure rocker arm and said opening rocker arm is pivotally connected to said cylinder head.
Claim 13
Dependent Claim
63 words
An adjustable valve train for an internal combustion engine as set forth in claim 9 wherein a side face of one of said closure rocker arm and said opening rocker arm is engaged by an alignment means for restricting said one of said closure rocker arm and said opening rocker arm pivotally connected to said cylinder head to pivot about said first axis.
Claim 14
Dependent Claim
59 words
An adjustable valve train for an internal combustion engine as set forth in claim 8 wherein said first pivoting axis is defined by a pair of ball and socket joints, arranged on a line parallel to said cam shaft, by which one of said closure rocker arm and said opening rocker arm is pivotally connected to said cylinder head.
Claim 15
Dependent Claim
54 words
An adjustable valve train for an internal combustion engine as set forth in claim 8 wherein said first pivoting axis is defined by a rocker shaft whose axis extends parallel to said cam shaft, by which one of said closure rocker arm and said opening rocker arm is pivotally connected to said cylinder head.
Claim 16
Dependent Claim
47 words
An adjustable valve train for an internal combustion engine as set forth in claim 8 wherein said closure or said opening rocker arm is pivotally connected to said cylinder head to pivot at said first axis and said second axis is defined at a central section thereof.
Claim 17
Dependent Claim
153 words
In a variable valve timing arrangement for operating a valve of an internal combustion engine: a rotatably driven camshaft, said cam shaft being supported in said engine so as to be axially displaceable therein; servo means for selectively displacing said cam shaft along the axis thereof; first and second cams mounted on said cam shaft, said first and second cams having first and second predetermined cam configurations; a first rocker arm operatively interconnecting said valve and said cam shaft, said first rocker arm being arranged to be motivated by said first cam in a manner to open said valve; a second rocker arm operatively interconnecting said valve and said cam shaft, said second rocker arm being arranged to be motivated by said second cam in a manner to close said valve; and means associated with said first and second rocker arms for obviating movement thereof in the axial direction of said cam shaft.
Claim 18
Dependent Claim
153 words
In a variable valve timing arrangement for operating a valve of an internal combustion engine: a rotatably driven camshaft, said cam shaft being supported in said engine so as to be axially displaceable therein; servo means for selectively displacing said cam shaft along the axis thereof; first and second cams mounted on said cam shaft, said first and second cams having first and second predetermined cam configurations; a first rocker arm operatively interconnecting said valve and said cam shaft, said first rocker arm being arranged to be motivated by said first cam in a manner to open said valve; a second rocker arm operatively interconnecting said valve and said cam shaft, said second rocker arm being arranged to be motivated by said second cam in a manner to close said valve; and means associated with said first and second rocker arms for obviating movement thereof in the axial direction of said cam shaft.
References Cited (Backward Citations)
No citation records indexed.
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