US4862845A — Variable camshaft timing system

Claim 1

Independent Claim 90 words

A variable camshaft timing system for an internal combustion engine having intake and exhaust valves and a camshaft for each of said intake and exhaust valves, an intake sprocket and an exhaust sprocket keyed to their respective camshaft, only one of said camshafts being directly driven by an engine crankshaft, and a timing chain engaging both sprockets, the improvement comprising a single bracket carrying at least one idler sprocket engaging said timing chain, said bracket being mounted for movement to alter the timing relationship between said intake and exhaust sprockets.

Claim 2

Dependent Claim 90 words

A variable camshaft timing system for an internal combustion engine having intake and exhaust valves and a camshaft for each of said intake and exhaust valves, an intake sprocket and an exhaust sprocket keyed to their respective camshaft, only one of said camshafts being directly driven by an engine crankshaft, and a timing chain engaging both sprockets, the improvement comprising a single bracket carrying at least one idler sprocket engaging said timing chain, said bracket being mounted for movement to alter the timing relationship between said intake and exhaust sprockets.

Claim 3

Dependent Claim 99 words

A variable camshaft timing system for an internal combustion engine having intake and exhaust valves and a camshaft for each of said intake and exhaust valves, an intake sprocket and an exhaust sprocket keyed to their respective camshafts, one camshaft being driven by an engine crankshaft, and a timing chain engaging both sprockets, the improvement comprising a single bracket having a pair of spaced idler sprockets engaging said chain between said intake and exhaust sprockets to form a generally rhomboidal path for the chain, said bracket being adjustable to alter the timing relationship between said intake and exhaust sprockets.

Claim 4

Dependent Claim 99 words

A variable camshaft timing system for an internal combustion engine having intake and exhaust valves and a camshaft for each of said intake and exhaust valves, an intake sprocket and an exhaust sprocket keyed to their respective camshafts, one camshaft being driven by an engine crankshaft, and a timing chain engaging both sprockets, the improvement comprising a single bracket having a pair of spaced idler sprockets engaging said chain between said intake and exhaust sprockets to form a generally rhomboidal path for the chain, said bracket being adjustable to alter the timing relationship between said intake and exhaust sprockets.

Claim 5

Dependent Claim 23 words

A variable camshaft timing system as set forth in claim 1, wherein said bracket includes an idler sprocket and a spaced chain tensioner.

Claim 6

Dependent Claim 22 words

A variable camshaft timing system as set forth in claim 2, wherein chain control devices can be integrated into said bracket design.

Claim 7

Dependent Claim 39 words

A variable camshaft timing system as set forth in claim 1, wherein a timing mark on the exhaust sprocket remains stationary while the timing setting of the intake sprocket will change upon movement of said bracket and idler sprocket.

Claim 8

Dependent Claim 108 words

A variable camshaft timing system for an internal combustion engine having intake and exhaust valves and a camshaft for each of said intake and exhaust valves, an intake sprocket and an exhaust sprocket keyed to their respective camshafts, one camshaft being driven by an engine crankshaft, and a timing chain engaging both sprockets, the improvement comprising a single L-shaped bracket pivotally mounted on one of said camshafts and having a pair of spaced idler sprockets rotatably mounted on the legs of said bracket, and means for adjustably moving said bracket to alter the positions of said idler sprockets and the timing relationship batten said intake and exhaust sprockets.

Claim 9

Dependent Claim 108 words

A variable camshaft timing system for an internal combustion engine having intake and exhaust valves and a camshaft for each of said intake and exhaust valves, an intake sprocket and an exhaust sprocket keyed to their respective camshafts, one camshaft being driven by an engine crankshaft, and a timing chain engaging both sprockets, the improvement comprising a single L-shaped bracket pivotally mounted on one of said camshafts and having a pair of spaced idler sprockets rotatably mounted on the legs of said bracket, and means for adjustably moving said bracket to alter the positions of said idler sprockets and the timing relationship batten said intake and exhaust sprockets.

Claim 10

Dependent Claim 27 words

A variable camshaft timing system as set forth in claim 6, in which said bracket includes a chain tensioner and at least one snubber for the chain.

Claim 11

Dependent Claim 24 words

A variable camshaft timing system as set forth in claim 6, wherein said bracket has a centrally located pivotal mounting cooperating with said camshaft.

Claim 12

Dependent Claim 108 words

A variable camshaft timing system for an internal combustion engine having intake and exhaust valves and a camshaft for each of said intake and exhaust valves, an intake sprocket and an exhaust sprocket keyed to their respective camshafts, one camshaft being driven by an engine crankshaft, and a timing chain engaging both sprockets, the improvement comprising a primary bracket carrying an idler sprocket and a secondary bracket carrying a second idler sprocket, at least said primary bracket being pivotally mounted on a camshaft, and a tensioner in one bracket urging said brackets apart, said brackets being adjustable to alter the timing relationship between said intake and exhaust sprockets.

Claim 13

Dependent Claim 108 words

A variable camshaft timing system for an internal combustion engine having intake and exhaust valves and a camshaft for each of said intake and exhaust valves, an intake sprocket and an exhaust sprocket keyed to their respective camshafts, one camshaft being driven by an engine crankshaft, and a timing chain engaging both sprockets, the improvement comprising a primary bracket carrying an idler sprocket and a secondary bracket carrying a second idler sprocket, at least said primary bracket being pivotally mounted on a camshaft, and a tensioner in one bracket urging said brackets apart, said brackets being adjustable to alter the timing relationship between said intake and exhaust sprockets.

Claim 14

Dependent Claim 21 words

A variable camshaft timing system as set forth in claim 9, wherein both brackets are pivotally mounted on the same camshaft.

Claim 15

Dependent Claim 36 words

A variable camshaft timing system as set forth in claim 9, wherein said secondary bracket is pivotally mounted on said primary bracket, and said tensioner is carried by said primary bracket to urge said brackets apart.

Claim 16

Dependent Claim 23 words

A variable camshaft timing system as set forth in claim 9, wherein said secondary bracket is yieldably urged away from said primary bracket.

Claim 17

Dependent Claim 31 words

A variable camshaft timing system as set forth in claim 12, wherein said secondary bracket has a piston opposite its idler sprocket received in a cylinder formed in said primary bracket.

Claim 18

Dependent Claim 105 words

A variable camshaft timing system for an internal combustion engine having intake and exhaust valves and a camshaft for each of said intake and exhaust valves, an intake sprocket and an exhaust sprocket keyed to their respective camshafts, one camshaft being driven by an engine crankshaft, and a timing chain engaging both sprockets, the improvement comprising a bracket pivotally mounted on a camshaft and carrying an idler sprocket, and a chain tensioner yieldably urged away from and carried by said bracket to engage the chain opposite to said idler sprocket, said bracket being adjustable to alter the timing relationship between said intake and exhaust sprockets.

Claim 19

Dependent Claim 105 words

A variable camshaft timing system for an internal combustion engine having intake and exhaust valves and a camshaft for each of said intake and exhaust valves, an intake sprocket and an exhaust sprocket keyed to their respective camshafts, one camshaft being driven by an engine crankshaft, and a timing chain engaging both sprockets, the improvement comprising a bracket pivotally mounted on a camshaft and carrying an idler sprocket, and a chain tensioner yieldably urged away from and carried by said bracket to engage the chain opposite to said idler sprocket, said bracket being adjustable to alter the timing relationship between said intake and exhaust sprockets.

Claim 20

Dependent Claim 27 words

A variable camshaft timing system as set forth in claim 14, in which said tensioner has an enlarged head with a curved outer surface engaging the chain.

Claim 21

Dependent Claim 45 words

A variable camshaft timing system as set forth in claim 1, wherein said bracket is an elongated member having a longitudinal axis and carries an idler sprocket at each end, and means to move said bracket in a linear direction parallel to said longitudinal axis.

Claim 22

Dependent Claim 23 words

A variable camshaft timing device a set forth in claim 16, wherein said bracket is formed of two parts longitudinally yieldably urged apart.

Claim 23

Dependent Claim 21 words

A variable camshaft timing system as set forth in claim 17, wherein one portion of the bracket provides a chain tensioner.

Claim 24

Dependent Claim 61 words

A variable camshaft timing system as set forth in claim 1, wherein said bracket is elongated with a longitudinal axis and mounted for linear motion in the direction of said axis, said bracket carrying an idler sprocket at one end and a chain tensioner at the opposite end, said tensioner having an enlarged head with a curved surface engaging said chain.

Claim 25

Dependent Claim 26 words

A variable camshaft timing system as set forth in claim 19, wherein said tensioner is yieldably urged away from the idler sprocket in the longitudinal direction.

Claim 26

Dependent Claim 32 words

A variable camshaft timing system as set forth in claim 16, wherein said bracket is mounted for linear movement in a direction other than parallel to the longitudinal axis of the bracket.

Claim 27

Dependent Claim 40 words

A variable camshaft timing system as set forth in claim 21, wherein the path of the chain has a rhomboid shape and the path of travel of said bracket is parallel to a pair of opposed strands of the chain.

Claim 28

Dependent Claim 22 words

A variable camshaft timing system as set forth in claim 21, wherein chain control means are mounted on the stationary engine surface.

Claim 29

Independent Claim 73 words

A method of adjusting the timing of a pair of camshafts for an internal combustion engine wherein each camshaft has a sprocket and a timing chain engaging said sprockets to provide a camshaft-to-camshaft drive, the method comprising providing a bracket carrying at least one idler sprocket engaging said chain, and shifting said bracket relative to one camshaft to alter the chain path and angular position of the camshaft sprockets relative to each other.

Claim 30

Independent Claim 73 words

A method of adjusting the timing of a pair of camshafts for an internal combustion engine wherein each camshaft has a sprocket and a timing chain engaging said sprockets to provide a camshaft-to-camshaft drive, the method comprising providing a bracket carrying at least one idler sprocket engaging said chain, and shifting said bracket relative to one camshaft to alter the chain path and angular position of the camshaft sprockets relative to each other.

Claim 31

Dependent Claim 26 words

A method as set forth in claim 24, wherein said method includes the step of pivoting said bracket about the axis of one of the camshafts.

Claim 32

Dependent Claim 29 words

A method as set forth in claim 25, wherein said bracket includes a pair of spaced idler sprockets which are shifted at the same rate over the actuation range.

Claim 33

Dependent Claim 22 words

A method as set forth in claim 25, including providing means associated with said bracket to control the tension of said chain.

Claim 34

Dependent Claim 24 words

A method as set forth in claim 24, wherein said method includes the step of shifting said bracket along a linear path of movement.

Claim 35

Dependent Claim 21 words

A method as set forth in claim 28, wherein said bracket carries a pair of idler sprockets at each end thereof.

Claim 36

Independent Claim 92 words

A method of adjusting the timing of a pair of camshafts for an internal combustion engine wherein each camshaft has a sprocket and a timing chain engaging said sprockets, the method comprising providing a bracket carrying an idler sprocket at each end engaging said chain, and shifting said bracket along a linear path of movement relative to one camshaft to alter the chain path and angular position of the camshaft sprockets relative to each other, said bracket being shifted along a path perpendicular to a line intersecting the axes of said camshafts.

Claim 37

Independent Claim 92 words

A method of adjusting the timing of a pair of camshafts for an internal combustion engine wherein each camshaft has a sprocket and a timing chain engaging said sprockets, the method comprising providing a bracket carrying an idler sprocket at each end engaging said chain, and shifting said bracket along a linear path of movement relative to one camshaft to alter the chain path and angular position of the camshaft sprockets relative to each other, said bracket being shifted along a path perpendicular to a line intersecting the axes of said camshafts.

Claim 38

Dependent Claim 27 words

A method as set forth in claim 29, in which said bracket is shifted along a path parallel to a pair of opposite strands of said chain.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-09-04	1993-03-06	1993-09-05	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-09-04	1997-03-06	1997-09-05	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-09-04	2001-03-06	2001-09-05	$7700.00	Window Closed / Lapsed

Variable camshaft timing system

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