Variable camshaft timing for internal combustion engine

Claim 2

An internal combustion engine comprising: a crankshaft; a camshaft, said camshaft being rotatable about its longitudinal central axis; first means mounted on said camshaft, said first means being oscillatable with respect to said camshaft about said longitudinal central axis at least through a limited arc; second means keyed to said camshaft for rotation therewith; rotary movement transmitting means interconnecting said crankshaft and one of said first means and said second means for transmitting rotary movement from said crankshaft to said camshaft; a first hydraulic cylinder having a body end pivotably attached to one of said first means and said second means and a piston end pivotably attached to the other of said first means and said second means; a second hydraulic cylinder having a body end pivotably attached to said one of said first means and said second means and a piston end pivotably attached to said other of said first means and said second means, said second hydraulic cylinder and said first hydraulic cylinder being disposed to act in opposite directions with respect to said longitudinal central axis and being hydraulically interconnected so that one of said first hydraulic cylinder and said second hydraulic cylinder extends as the other of said first hydraulic cylinder and said second hydraulic cylinder retracts; and control means for selectively permitting the extending of one of said first hydraulic cylinder and said second hydraulic cylinder and the retracting of the other of said first hydraulic cylinder and said second hydraulic cylinder in reaction to torque pulsations in said camshaft.

Claim 3

An internal combustion engine comprising: a crankshaft; a camshaft, said camshaft being rotatable about its longitudinal central axis; first means mounted on said camshaft, said first means being oscillatable with respect to said camshaft about said longitudinal central axis at least through a limited arc; second means keyed to said camshaft for rotation therewith; power transmitting means interconnecting said crankshaft and one of said first means and said second means for transmitting rotary movement from said crankshaft to said camshaft; a first hydraulic cylinder having a body end pivotably attached to one of said first means and said second means and a piston end pivotably attached to the other of said first means and said second means; a second hydraulic cylinder having a body end pivotably attached to said one of said first means and said second means and a piston end pivotably attached to said other of said first and second means, said first hydraulic cylinder and said second hydraulic cylinder being disposed to act in opposite directions with respect to said longitudinal central axis; hydraulic means interconnecting said first hydraulic cylinder and said second hydraulic cylinder so that one of said first hydraulic cylinder and said second hydraulic cylinder extends as the other of said first hydraulic cylinder and said second hydraulic cylinder retracts, said hydraulic means including control valve means for permitting one or another of said first hydraulic cylinder and said second hydraulic cylinder to extend and the other of said first hydraulic cylinder and said second hydraulic cylinder to retract in reaction to torque pulsations in said camshaft; and control means for controlling the operation of said control valve means.

Claim 4

An internal combustion engine comprising: a crankshaft; a camshaft, said camshaft being rotatable about its longitudinal central axis; first means mounted on said camshaft, said first means being oscillatable with respect to said camshaft about said longitudinal central axis at least through a limited arc; second means keyed to said camshaft for rotation therewith; power transmitting means interconnecting said crankshaft and one of said first means and said second means for transmitting rotary movement from said crankshaft to said camshaft; a first hydraulic cylinder having a body end pivotably attached to one of said first means and said second means and a piston end pivotably attached to the other of said first means and said second means; a second hydraulic cylinder having a body end pivotably attached to said one of said first means and said second means and a piston end pivotably attached to said other of said first and second means, said first hydraulic cylinder and said second hydraulic cylinder being disposed to act in opposite directions with respect to said longitudinal central axis; hydraulic means interconnecting said first hydraulic cylinder and said second hydraulic cylinder so that one of said first hydraulic cylinder and said second hydraulic cylinder extends as the other of said first hydraulic cylinder and said second hydraulic cylinder retracts, said hydraulic means including control valve means for permitting one or another of said first hydraulic cylinder and said second hydraulic cylinder to extend and the other of said first hydraulic cylinder and said second hydraulic cylinder to retract in reaction to torque pulsations in said camshaft; and control means for controlling the operation of said control valve means.

Claim 5

In an internal combustion engine having a rotatable crankshaft, at least one rotatable camshaft, the at least one camshaft being position variable relative to the crankshaft and being subject to torque reversals during the rotation thereof, the at least one camshaft further being subject to a unidirectionally acting torque during the rotation thereof, the method comprising: providing oppositely acting first and second hydraulic means for varying the position of the at least one camshaft; varying the position of the at least one camshaft relative to the crankshaft by transferring hydraulic fluid from one of the first and second hydraulic means to the other of the first and second hydraulic means; actuating the means for varying of the position of the at least one camshaft relative to the crankshaft in reaction to torque reversals in the at least one camshaft; and imposing a resilient force on one of the first and second hydraulic means to substantially neutralize the effects of the unidirectionally acting torque.

Claim 6

In an internal combustion engine having a rotatable crankshaft, at least one rotatable camshaft, the at least one camshaft being position variable relative to the crankshaft and being subject to torque reversals during the rotation thereof, the at least one camshaft further being subject to a unidirectionally acting torque during the rotation thereof, the method comprising: providing oppositely acting first and second hydraulic means for varying the position of the at least one camshaft; varying the position of the at least one camshaft relative to the crankshaft by transferring hydraulic fluid from one of the first and second hydraulic means to the other of the first and second hydraulic means; actuating the means for varying of the position of the at least one camshaft relative to the crankshaft in reaction to torque reversals in the at least one camshaft; and imposing a resilient force on one of the first and second hydraulic means to substantially neutralize the effects of the unidirectionally acting torque.

Claim 7

The method of claim 3 wherein the imposing of a resilient force on one of the first and second hydraulic means is accomplished by providing a torsional spring having a first end fixedly positioned relative to one of said first and second hydraulic means and a second end fixedly positioned relative to the other of said first and second hydraulic means.

Claim 8

The method of claim 3 wherein the first and second hydraulic means are first and second oppositely acting hydraulic cylinders, and wherein the imposing of a resilient force on one of the first and second hydraulic means is accomplished by providing a compression spring to act on a piston portion of one of said first and second hydraulic cylinders.

Claim 9

In an internal combustion engine having a rotatable crankshaft, at least one rotatable camshaft, and an engine control unit for controlling the operation of the engine, the at least one camshaft being position variable relative to the crankshaft and being subject to torque reversals, the camshaft further being subject to a unidirectionally acting torque during the rotation thereof, the method of varying the position of the at least one camshaft relative to the crankshaft comprising: actuating, in response to a control signal from the engine control unit, the means for varying of the position of the at least one camshaft in reaction to torque reversals in the at least one camshaft; and subjecting the camshaft to a countertorque acting in a direction opposed to the unidirectionally acting torque.

Claim 10

In an internal combustion engine having a rotatable crankshaft, at least one rotatable camshaft, and an engine control unit for controlling the operation of the engine, the at least one camshaft being position variable relative to the crankshaft and being subject to torque reversals, the camshaft further being subject to a unidirectionally acting torque during the rotation thereof, the method of varying the position of the at least one camshaft relative to the crankshaft comprising: actuating, in response to a control signal from the engine control unit, the means for varying of the position of the at least one camshaft in reaction to torque reversals in the at least one camshaft; and subjecting the camshaft to a countertorque acting in a direction opposed to the unidirectionally acting torque.

Claim 11

The method according to claim 6 wherein the step of actuating is performed by: providing oppositely acting first and second hydraulic means for varying the position of the at least one camshaft; and transferring hydraulic fluid from one of the first and second hydraulic means to the other of the first and second hydraulic means when permitted by a control signal from the engine control unit; and wherein the step of subjecting the camshaft to a countertorque is performed by providing resilient means acting on one of said first and second hydraulic means.

Claim 12

An internal combustion engine comprising: a rotatable crankshaft; a camshaft, said camshaft being rotatable about its longitudinal central axis and being subject to a unidirectionally acting torque during the rotation thereof; first means mounted on said camshaft, said first means being oscillatable with respect to said camshaft about said longitudinal central axis of said camshaft at least through a limited arc; second means keyed to said camshaft for rotation therewith; rotary movement transmitting means interconnecting said crankshaft and one of said first means and said second means for transmitting rotary movement from said crankshaft to said camshaft; a first hydraulic cylinder having a body end pivotably attached to one of said first means and said second means and a piston end pivotably attached to the other of said first means and said second means; a second hydraulic cylinder having a body end pivotably attached to said one of said first means and said second means and a piston end pivotably attached to said other of said first means and said second means, said second hydraulic cylinder and said first hydraulic cylinder being disposed to act in opposite directions with respect to said longitudinal central axis of said camshaft and being hydraulically interconnected so that one of said first hydraulic cylinder and said second hydraulic cylinder extends as the other of said first hydraulic cylinder and said second hydraulic cylinder retracts; resilient means acting on one of said first means and said second means to impose a countertorque on said camshaft during the rotation thereof, the countertorque being opposed in direction to the unidirectionally acting torque; and control means for selectively permitting the extending of one of said first hydraulic cylinder and said second hydraulic cylinder and the retracting of the other of said first hydraulic cylinder and said second hydraulic cylinder in reaction to torque pulsations in said camshaft.

Claim 13

An internal combustion engine comprising: a rotatable crankshaft; a camshaft, said camshaft being rotatable about its longitudinal central axis and being subject to a unidirectionally acting torque during the rotation thereof; first means mounted on said camshaft, said first means being oscillatable with respect to said camshaft about said longitudinal central axis of said camshaft at least through a limited arc; second means keyed to said camshaft for rotation therewith; rotary movement transmitting means interconnecting said crankshaft and one of said first means and said second means for transmitting rotary movement from said crankshaft to said camshaft; a first hydraulic cylinder having a body end pivotably attached to one of said first means and said second means and a piston end pivotably attached to the other of said first means and said second means; a second hydraulic cylinder having a body end pivotably attached to said one of said first means and said second means and a piston end pivotably attached to said other of said first means and said second means, said second hydraulic cylinder and said first hydraulic cylinder being disposed to act in opposite directions with respect to said longitudinal central axis of said camshaft and being hydraulically interconnected so that one of said first hydraulic cylinder and said second hydraulic cylinder extends as the other of said first hydraulic cylinder and said second hydraulic cylinder retracts; resilient means acting on one of said first means and said second means to impose a countertorque on said camshaft during the rotation thereof, the countertorque being opposed in direction to the unidirectionally acting torque; and control means for selectively permitting the extending of one of said first hydraulic cylinder and said second hydraulic cylinder and the retracting of the other of said first hydraulic cylinder and said second hydraulic cylinder in reaction to torque pulsations in said camshaft.

Claim 14

An internal combustion engine according to claim 8 wherein said resilient means is a compression spring, said compression spring acting on a piston portion of one of said first hydraulic cylinder and said second hydraulic cylinder.

Claim 15

An internal combustion engine according to claim 8 wherein said resilient means is a torsional spring, said torsional spring having a first end secured to one of said first means and said second means and a second end secured to the other of said first means and said second means.

Claim 16

An internal combustion engine according to claim 8 wherein one of said first means and said second means is a sprocket, wherein said rotary movement transmitting means is a chain and wherein said sprocket is driven by said chain.

Claim 17

An internal combustion engine comprising: a rotatable crankshaft; at least two camshafts, each of said at least two camshafts being rotatable about its longitudinal central axis and being subject to a unidirectionally acting torque during the rotation thereof; first means mounted on a first of said at least two camshafts, said first means being oscillatable with respect to said first of said at least two camshafts about the longitudinal central axis of said first of said at least two camshafts at least through a limited arc; second means keyed to a second of said at least two camshafts for rotation therewith; rotary movement transmitting means interconnecting said crankshaft and said first means and said second means for transmitting rotary movement from said crankshaft to said at least two camshafts; a first hydraulic cylinder having a body end pivotably attached to one of said first means and said second means and a piston end pivotably attached to the other of said first means and said second means; a second hydraulic cylinder having a body end pivotably attached to said one of said first means and said second means and a piston end pivotably attached to said other of said first means and said second means, said second hydraulic cylinder and said first hydraulic cylinder being disposed to act in opposite directions with respect to the longitudinal central axis of one of said at least two camshafts being hydraulically interconnected so that one of said first hydraulic cylinder and said second hydraulic cylinder extends as the other of said first hydraulic cylinder and said second hydraulic cylinder retracts; resilient means acting on one of said first means and said second means to impose a countertorque on said one of said at least two camshafts during the rotation thereof, the countertorque being opposed in direction to the unidirectionally acting torque; and control means for selectively permitting the extending of one of said first hydraulic cylinder and said second hydraulic cylinder and the retracting of the other of said first hydraulic cylinder and said second hydraulic cylinder in reaction to torque pulsations in said at least one camshaft.

Claim 18

An internal combustion engine comprising: a rotatable crankshaft; at least two camshafts, each of said at least two camshafts being rotatable about its longitudinal central axis and being subject to a unidirectionally acting torque during the rotation thereof; first means mounted on a first of said at least two camshafts, said first means being oscillatable with respect to said first of said at least two camshafts about the longitudinal central axis of said first of said at least two camshafts at least through a limited arc; second means keyed to a second of said at least two camshafts for rotation therewith; rotary movement transmitting means interconnecting said crankshaft and said first means and said second means for transmitting rotary movement from said crankshaft to said at least two camshafts; a first hydraulic cylinder having a body end pivotably attached to one of said first means and said second means and a piston end pivotably attached to the other of said first means and said second means; a second hydraulic cylinder having a body end pivotably attached to said one of said first means and said second means and a piston end pivotably attached to said other of said first means and said second means, said second hydraulic cylinder and said first hydraulic cylinder being disposed to act in opposite directions with respect to the longitudinal central axis of one of said at least two camshafts being hydraulically interconnected so that one of said first hydraulic cylinder and said second hydraulic cylinder extends as the other of said first hydraulic cylinder and said second hydraulic cylinder retracts; resilient means acting on one of said first means and said second means to impose a countertorque on said one of said at least two camshafts during the rotation thereof, the countertorque being opposed in direction to the unidirectionally acting torque; and control means for selectively permitting the extending of one of said first hydraulic cylinder and said second hydraulic cylinder and the retracting of the other of said first hydraulic cylinder and said second hydraulic cylinder in reaction to torque pulsations in said at least one camshaft.

Claim 19

An internal combustion engine according to claim 12 wherein said resilient means is a compression spring, said compression spring acting on a piston portion of one of said first hydraulic cylinder and said second hydraulic cylinder.

Claim 20

An internal combustion engine according to claim 12 wherein said resilient means is a torsional spring, said torsional spring having a first end secured to one of said first means and said second means and a second end secured to the other of said first means and said second means.

Claim 21

An internal combustion engine according to claim 12 wherein one of said first means and said second means is a sprocket, wherein said rotary movement transmitting means is a chain, and wherein said sprocket is driven by said chain.

Claim 22

An internal combustion engine comprising: a rotatable crankshaft; only one camshaft, said camshaft being rotatable about its longitudinal central axis; first means mounted on said camshaft, said first means being oscillatable with respect to said camshaft about a longitudinal central axis of said camshaft at least through a limited arc; second means keyed to said camshaft for rotation therewith; rotary movement transmitting means interconnecting said crankshaft and one of said first means and said second means for transmitting rotary movement from said crankshaft to said camshaft; a first hydraulic cylinder having a body end pivotably attached to one of said first means and said second means and a piston end pivotably attached to the other of said first means and said second means; a second hydraulic cylinder having a body end pivotably attached to said one of said first means and said second means and a piston end pivotably attached to said other of said first means and said second means, said second hydraulic cylinder and said first hydraulic cylinder being disposed to act in opposite directions with respect to said longitudinal central axis of said camshaft and being hydraulically interconnected so that one of said first hydraulic cylinder and said second hydraulic cylinder extends as the other of said first hydraulic cylinder and said second hydraulic cylinder retracts; and control means for selectively permitting the extending of one of said first hydraulic cylinder and said second hydraulic cylinder and the retracting of the other of said first hydraulic cylinder and said second hydraulic cylinder in reaction to torque pulsations in said camshaft.

Claim 23

An internal combustion engine comprising: a rotatable crankshaft; only one camshaft, said camshaft being rotatable about its longitudinal central axis; first means mounted on said camshaft, said first means being oscillatable with respect to said camshaft about a longitudinal central axis of said camshaft at least through a limited arc; second means keyed to said camshaft for rotation therewith; rotary movement transmitting means interconnecting said crankshaft and one of said first means and said second means for transmitting rotary movement from said crankshaft to said camshaft; a first hydraulic cylinder having a body end pivotably attached to one of said first means and said second means and a piston end pivotably attached to the other of said first means and said second means; a second hydraulic cylinder having a body end pivotably attached to said one of said first means and said second means and a piston end pivotably attached to said other of said first means and said second means, said second hydraulic cylinder and said first hydraulic cylinder being disposed to act in opposite directions with respect to said longitudinal central axis of said camshaft and being hydraulically interconnected so that one of said first hydraulic cylinder and said second hydraulic cylinder extends as the other of said first hydraulic cylinder and said second hydraulic cylinder retracts; and control means for selectively permitting the extending of one of said first hydraulic cylinder and said second hydraulic cylinder and the retracting of the other of said first hydraulic cylinder and said second hydraulic cylinder in reaction to torque pulsations in said camshaft.