CN106368759B

CN106368759B - System for varying cylinder valve timing in an internal combustion engine

Info

Publication number: CN106368759B
Application number: CN201610584355.9A
Authority: CN
Inventors: A·特维斯; A·施米特; B·黑德曼; D·瓦德勒
Original assignee: Husco Automotive Holdings LLC
Current assignee: Husco Automotive Holdings LLC
Priority date: 2015-07-24
Filing date: 2016-07-22
Publication date: 2020-08-04
Anticipated expiration: 2036-07-22
Also published as: EP3121396A1; CN106368759A; EP3121396B1; JP2017025919A

Abstract

A control system for changing cylinder valve timing of an internal combustion engine is provided. The control system includes a cam phase actuator having first and second actuator ports to adjust a rotational phase of a camshaft relative to a crankshaft, a first control valve, a second control valve, and a dynamic regeneration valve. In one embodiment, the dynamic regeneration valve is configured to enable the cam phase actuator to switch between operating in an oil pressure actuation mode and a cam torque actuation mode when adjusting a rotational phase of the camshaft relative to the crankshaft.

Description

System for varying cylinder valve timing in an internal combustion engine

Cross Reference to Related Applications

This application is a continuation-in-part application entitled "System for Varying Cylinder valve timing in an Internal Combustion Engine" filed on 11.3.2013, entitled "System for Varying Cylinder valve timing" and is incorporated herein by reference.

Technical Field

The present invention relates to a cylinder variable valve timing system for an internal combustion engine, and particularly to an apparatus for hydraulically operating an actuator that changes the phase relationship between a crankshaft and a camshaft.

Background

Internal combustion engines have a plurality of cylinders containing pistons connected to drive a crankshaft. Each cylinder has two or more valves that control the flow of air into the cylinder and the flow of exhaust gas out of the cylinder. The camshaft operates the cylinder valves and is mechanically connected for rotation by a crankshaft. Gears, chains or belts are used to couple the crankshaft to the camshaft. Importantly, the valves open and close at the appropriate times during the combustion cycle of each cylinder. Heretofore, the valve timing relationship has been fixed by a mechanical coupling between the crankshaft and the camshaft.

The fixed setting of valve timing is a compromise that produces the best overall operation at all operating speeds of the engine. However, it has been recognized that optimal engine characteristics can be obtained if the valve timing is varied according to engine speed, engine load, and other factors. With the advent of computer control of engines, it has become possible to determine optimal cylinder valve timing based on current operating conditions and adjust that timing accordingly.

An exemplary variable cylinder timing system is shown in fig. 1, wherein an engine computer 11 determines optimal valve timing and current applied to a four-way electro-hydraulic valve 10, which 10 controls the flow of pressurized oil from a pump 13 to a cam phase actuator 12. The pump 13 is typically a conventional pump used to deliver lubricating oil through the engine. The cam phase actuator 12 couples the camshaft 14 to a pulley 16, and a timing belt engaging another pulley on the engine crankshaft drives the pulley 16. Instead of pulleys, a chain sprocket, gear, or other device may be used to mechanically couple camshaft 14 to the crankshaft. The sensor 15 provides a feedback electrical signal to the engine computer 11 that is indicative of the angular phase of the camshaft 14.

Referring additionally to fig. 2, the cam phase actuator 12 has a rotor 20 fixed to the camshaft 14. The cam phase actuator 12 has four lobes 22 that project outwardly into four chambers 25 in the timing pulley 16, thereby forming first and

second cavities

26 and 28 in each chamber on opposite sides of the respective lobe. The first port 18 in the actuator manifold 15 is connected to the first cavity 26 by a first passage 30, while a second passage 33 connects the second port 19 to the second cavity 28.

By selectively controlling the application of engine oil to the first and

second ports

18 and 19 of the cam phase actuator 12, the angular phase relationship between the rotating pulley 16 and the camshaft 14 may be varied to advance or retard cylinder valve timing. When the electro-hydraulic valve 10 is energized into a center, or neutral, position, fluid from the pump 10 is likewise fed into the first and

second cavities

26 and 28 in each timing pulley chamber 25. Equal pressure on both sides of rotor impeller 22 maintains the current position of the impeller within pulley chamber 25. Most of the time the engine is running, the electro-hydraulic valve 10 is running in a central position. It should be noted that current must be applied to the electro-hydraulic valve 10 to maintain this central position.

In another position of the electro-hydraulic valve 10, pressurized oil from the pump 13 is applied to the first port 18 and additional oil is discharged from the second port 19 to the reservoir 17 (e.g., an oil pan). The pressurized oil is communicated into the first cavity 26, thereby forcing the rotor 20 to rotate clockwise relative to the timing pulley 16 and advancing the valve timing. In another position of the electro-hydraulic valve 10, pressurised oil from the pump is applied to the second port 19, whilst oil is drained from the first port 18 to the reservoir 17. Pressurized oil is now delivered into the second cavity 28, thereby forcing the rotor 20 to rotate counterclockwise relative to the timing pulley 16, which retards valve timing.

References herein to directional relationships and movement, such as left and right, or clockwise and counterclockwise, refer to component relationships and movement of components in the orientation shown in the drawings, which may not be the same for components attached to the machine. The term "directly connected" as used herein means that the connected hydraulic components are connected together by conduits without any intervening elements, such as valves, orifices, or other devices, that restrict or control fluid flow beyond any conduit inherent restriction. Also as used herein, components that are referred to as being "fluidly connected" are operatively connected in a manner wherein fluid flows between the components.

Operation of cam phase actuator 12 requires significant oil pressure and flow from the engine oil pump to overcome the torque profile of the camshaft and adjust cam timing. Furthermore, the electro-hydraulic valve 10 consumes current when placed in a central position during most of the engine's operating time. There is a need to reduce the consumption of hydraulic and electrical energy, thereby increasing the efficiency of cam phasing systems.

Disclosure of Invention

In one aspect, some embodiments of the present invention provide a control system for changing cylinder valve timing of an internal combustion engine. An internal combustion engine includes a pump, a reservoir, a crankshaft, and a camshaft. The control system includes a cam phase actuator for adjusting a rotational phase of a camshaft relative to a crankshaft and having a first actuator port and a second actuator port. The control system further includes a first control valve including a first port operatively connected to receive fluid from the pump, a second port, and a first workport in fluid communication with the first port of the cam phase actuator. The first control valve has a first position in which fluid communication between the first port and the first workport is provided and has a second position in which fluid communication between the second port and the first workport is provided. The control system further includes a second control valve including a third port operatively connected to receive fluid from the pump, a fourth port, and a second workport in fluid communication with the second actuator port. The second control valve has a first position in which fluid communication between the third port and the second workport is provided and has a second position in which fluid communication between the fourth port and the second workport is provided. The control system further includes a dynamic regeneration valve configured to enable the cam phase actuator to switch between operating in an oil pressure actuation mode and a cam torque actuation mode when adjusting a rotational phase of the camshaft relative to the crankshaft.

In another aspect, some embodiments of the present invention provide a control system for changing cylinder valve timing of an internal combustion engine. An internal combustion engine includes a pump, a reservoir, a crankshaft, and a camshaft. The control system includes a cam phase actuator for adjusting a rotational phase of a camshaft relative to a crankshaft and having a first actuator port and a second actuator port. The control system further includes a first control valve including a first port operatively connected to receive fluid from the pump, a second port, and a first workport in fluid communication with the first port of the cam phase actuator, the first control valve having a first position in which fluid communication between the first port and the first workport is provided and a second position in which fluid communication between the second port and the first workport is provided. The control system further includes a second control valve including a third port operatively connected to receive fluid from the pump, a fourth port, and a second workport in fluid communication with the second actuator port. The second control valve has one position providing fluid communication between the third port and the second workport and another position providing fluid communication between the fourth port and the second workport. The control system further includes a dynamic regeneration valve configured to switch operation of the cam phase actuator between an oil pressure actuated mode and a cam torque actuated mode based on a pressure at an outlet of the pump.

Drawings

The following figures illustrate examples of variable cam adjustment systems according to the present invention to understand other components and hydraulic circuits that may be used to implement the present invention.

FIG. 1 is a schematic diagram of a prior art variable cam adjustment system including a cam phase actuator.

Fig. 2 is a cross-sectional view of the cam phase actuator taken along line 2-2 of fig. 1.

Fig. 3 is a schematic diagram of a first embodiment of a hydraulic circuit according to the present invention.

Fig. 4 is a radial cross-sectional view through the cam phase actuator of the first embodiment.

Fig. 5 is a schematic diagram of a second embodiment of a hydraulic circuit according to the present invention.

FIG. 6 is a cross-sectional view of a dynamic regeneration valve according to an embodiment of the present invention.

FIG. 7 is a schematic diagram of a third embodiment of a hydraulic circuit operating in an oil pressure actuated mode according to the present invention.

FIG. 8 is a schematic illustration of the hydraulic circuit of FIG. 7 operating in a cam torque actuated mode.

FIG. 9 is a schematic diagram of the hydraulic circuit of FIG. 7 illustrating the use of dual camshafts.

FIG. 10 is a cross-sectional view of a dynamic regeneration valve according to another embodiment of the present invention.

FIG. 11 is a schematic diagram of a fourth embodiment of a hydraulic circuit operating in an oil pressure actuated mode according to the present invention.

FIG. 12 is a schematic diagram of the hydraulic circuit of FIG. 11 illustrating elevated pressure at the regeneration port.

FIG. 13 is a schematic illustration of the hydraulic circuit of FIG. 11 operating in a cam torque actuated mode.

FIG. 14 is a schematic diagram of the hydraulic circuit of FIG. 11 illustrating the use of dual camshafts.

Detailed Description

Referring first to fig. 3, a first cam phasing control system 40 utilizes oil supplied by a conventional oil pump 42, the oil pump 42 supplying oil from a reservoir 44 to lubricate the engine. The outlet of the oil pump 42 is connected to first and

second control valves

46 and 48. The

control valves

46 and 48 are electro-hydraulic, on/off, or proportional three-way valves, respectively, that are operated by signals from the engine computer 45. In one implementation, the engine computer 45 applies a Pulse Width Modulation (PWM) signal to operate an on/off three-way valve to effect a proportional change in fluid flow through the valve. Each

exemplary control valve

46 or 48 includes an

integrated check valve

50 or 52, respectively. The first control valve 46 has a first port 53 that receives oil from the oil pump 42 outlet and has a second port 55 that is in fluid communication with the reservoir 44 through a return line 56. When the first control valve 46 is in the first position as shown, a first path is provided between the first port 53 and the first workport 54. The first spring 61 biases the first control valve 46 toward the first position. The first check valve 50 allows oil to flow in the first path only from the first port 53 to the first workport 54 and prevents oil from flowing in the opposite direction. When the first solenoid actuator 63 is actuated by current from the engine computer 45, the first control valve 46 moves to the second position. In this second position, the first control valve 46 provides a bi-directional second path between the first work port 54 and the second port 55, and thus to the reservoir 44.

The second control valve 48 has a third port 57 connected to the outlet of the oil pump 42 and has a fourth port 59 connected to the reservoir 44 by a return line 56. In one position of the second control valve 48 shown, a third path is provided between the third port 57 and the second workport 58. The second spring 62 biases the second control valve 48 toward the one position. The second check valve 52 restricts fluid flow through the third path only in the direction from the third port 57 to the second workport 58. Another position of the second control valve 48 provides a bi-directional fourth fluid path between the second workport 58 and the fourth port 59. Current from the engine controller actuates the second solenoid actuator 64 to move the second control valve 48 to the other position.

The first cam phasing control system 40 includes a cam phasing actuator 68 for varying the rotational relationship between the crankshaft and the camshaft of the engine. The cam phase actuator 68 is a conventional hydraulically operated device used for this purpose and may be similar to the actuator shown in fig. 1 and 2. A cam phase actuator 68 has a first actuator port 66 directly connected to the first workport 54 of the first control valve 46 and has a second actuator port 70 directly connected to the second workport 58 of the second control valve 48.

When the engine computer does not apply current to the first and

second solenoid actuators

63 and 64, the two

control valves

46 and 48 are biased by

springs

61 and 62 to the positions shown in FIG. 3. In this state, an equal pressure from the outlet of the oil pump 42 is applied to the two

actuator ports

66 and 70 of the cam phase actuator 68. Because the first and

second check valves

50 and 52 in the first and

second control valves

46 and 48 prevent oil from flowing out of the cam phase actuator 68, the actuator remains in the present phase position even when the engine is at low speed when the pump outlet pressure is low and when the engine is off. Holding the cam phase actuator in the last operating position ensures: when the engine is restarted, the appropriate valve timing will be used, although initially the speed is low and the oil pressure generated by the oil pump 42 is lowest.

De-energizing the first and

second control valves

46 and 48 to maintain the position of the cam phase actuator 68, which conserves electrical power and hydraulic energy of the oil pump, as occurs most of the time the engine is running. Thus, current cam phasing systems consume less energy than prior systems that use a four-way control valve such as that shown in FIG. 1.

Existing cam phase actuators also require a locking mechanism to hold the actuator in a fixed position when the cam phase is not being adjusted. The first cam phasing control system 40 does not require a locking mechanism because the

check valves

50 and 52 hold oil within the cam phasing actuator 68 and prevent a change in the cam phasing relationship when the cam phasing actuator 68 is not adjusting.

With continued reference to fig. 3, the first cam phasing control system 40 provides bi-directional energy harvesting of cam torque for adjusting cam phasing. This also conserves energy and enables the phase of the cam to be adjusted near zero supply pressure.

To adjust the cam phase actuator 68 and advance cylinder valve timing, the first control valve 46 remains de-energized while the second control valve 48 is operated to a position where the second workport 58 is connected to the fourth port 59 connected to the return line 56. This enables pressurized fluid to be fed from the oil pump 42 into the first actuator port 66 while other fluid is drained from the second actuator port 70 back to the reservoir 44. This causes the cam phase actuator 68 to change the phase relationship between the crankshaft and the camshaft, and thereby advance the cylinder valve timing. When the cam phase reaches the desired angle, as detected by a sensor on the cam phase actuator, the engine computer de-energizes the second solenoid actuator 64, which returns the second control valve 48 to the position shown where the adjusted cam phase is maintained.

It should be appreciated that engine cylinder valves exert a torque on the camshaft that tends to change the positional relationship of components within the cam phase actuator and, thus, the phase relationship between the crankshaft and the camshaft. During certain rotational segments of the camshaft, the net torque helps to adjust the cam phase in the desired direction, thereby supplementing the adjustment force from the pump pressure. During other rotational segments of the camshaft, the net torque opposes the requested cam phasing. Throughout these latter sections, camshaft torque tends to cause cam phase actuator 68 to push oil back through first control valve 46 to oil pump 42. Such backflow may occur, for example, at low engine speeds when the pump produces a low output pressure. With the first cam phasing control system 40, the first and

second check valves

50 and 52 prevent this reverse flow, thereby enabling the system to effectively operate over a wide range of engine operating conditions, such as low pump output pressure, low oil temperature, and low engine speed. Thus, the present system utilizes net camshaft torque in the direction of rotation that helps adjust cam phasing while inhibiting the effects of adverse cam torque opposing the required cam phasing. In other words, the present control system achieves positive cam torque energy while preventing the adverse effects of negative cam torque energy.

Obtaining cam torque for adjusting cam phase conserves energy and enables adjustment of cam phase at near zero supply pressure.

To adjust the cam phase actuator 68 to retard cylinder valve timing, the first control valve 46 is electrically operated to connect the first working port 54 to the second port 55, thereby allowing fluid from the cam phase actuator to drain to the reservoir 44. At the same time, second control valve 48 is de-energized, and thus, spring 62 biases second control valve 48 into the position shown. In this position, oil output from the pump 42 is applied to the second work port 58 and the second actuator port 70 of the cam phase actuator 68. In this state, the second check valve 52 can harvest positive cam torque energy while inhibiting the adverse effects of negative cam torque energy.

It should be understood for the circuit shown in fig. 3 that the

check valves

50 and 52 are not integral to the first and

second control valves

46 and 48, and that the

check valves

50 and 52 may be located outside of each valve in the conduit connected to the respective first and third ports 53 and 57.

Still referring to fig. 3, if the engine has dual camshafts, a second cam phase actuator 72 is provided for the other camshaft, and the second cam phase actuator 72 has actuator ports 74 and 75 connected to 54 and 58 of the first and

second control valves

46 and 48, respectively. The first and second

cam phase actuators

68 and 72 are similar to the actuator 12 of fig. 1 and 2, except that the first passage 30 communicates with the first actuator port and the second passage 33 communicates with the second actuator port only during a portion of each revolution of the camshaft 14. Referring additionally to fig. 4, which shows details of the first cam phase actuator 68, the first actuator port 66 in the actuator manifold 76 opens into an arcuate recess 77, the recess 77 extending 90 degrees around the circumference of the bore in which the rotor 20 rotates. A radial bore 78 in the rotor 20 extends from the outer circumferential surface to the first passage 30, which continues to the first cavity 26. The arcuate recesses 77 of the manifold and the radial holes 78 of the rotor are arranged: when the camshafts are rotationally positioned between 0 and 90 degrees, they are in fluid communication. The second actuator port 70 of the first cam phase actuator 68 is similarly arranged to: when the camshaft is positioned between 0 and 90 degrees, it is in fluid communication with the second passage 33 for the second cavity 28. One skilled in the art will recognize that other angles and ranges of angles may be used to control two or more cam phase actuators.

The second cam phase actuator 72 is of similar design, except that the arcuate recess 77 is positioned: during each rotation, the first and second actuator ports 74 and 75 communicate with the first and

second passages

30 and 33, respectively, when the camshaft is rotationally positioned between 180 and 270 degrees. Because of the angular offset of the arcuate recesses, the first and

second pockets

26 and 28 of the first cam phase actuator 68 are actively connected to the

control valve workports

54 and 58 at different times during each camshaft rotation than the first and

second pockets

26 and 28 of the second cam phase actuator 72 are actively connected to the control valve workports. This enables independent control of the camshaft phasing provided by the two

cam phase actuators

68 and 72. The engine computer operates the

control valves

46 and 48 to change the phase of the first cam phase actuator 68 when the dual camshaft is positioned between 0 and 90 degrees and operates the control valves to change the phase of the second cam phase actuator 72 when the dual camshaft is positioned between 180 and 270 degrees.

Referring to fig. 5, a second embodiment of the present control system uses fluid exhausted from a cam phase actuator to provide regeneration. The regenerative circuit reduces the amount of oil required to flow from the pump to only that required to replace fluid leaking from the cam phase actuators and control valves to the engine.

In the second cam phasing control system 80, a conventional oil pump 82 feeds fluid from a reservoir 84 (e.g., an engine oil sump) to a pair of electro-hydraulic, three-

way control valves

86 and 88. The outlet of the oil pump 82 is connected to a first port 92 of the first control valve 86, the first control valve 86 also having a second port 94 and a first work port 93. The first workport 93 is directly connected to a first actuator port 106 of a cam phase actuator 104, and the second port 94 is coupled to a second actuator port 108 through a first regeneration line 100. The third check valve 95 allows oil to flow through the first regeneration line 100 only in a direction from the second port 94 to the second actuator port 108.

The outlet of the oil pump 82 is also connected to a third port 96 of a second control valve 88, the second control valve 88 having a fourth port 98 and a second work port 97. The second workport 97 is directly connected to a second actuator port 108 of the cam phase actuator 104, and the fourth port 98 is coupled to a first actuator port 106 by a second regeneration line 102. The fourth check valve 99 allows oil to flow through the second regeneration line 102 only in a direction from the fourth port 98 to the first actuator port 106.

If the engine has multiple camshafts, a separate cam phase actuator may be provided for each camshaft, and such actuators are coupled to the working

ports

93 and 97 of the two

control valves

86 and 88 in the same manner as the cam phase actuator 104.

When both control

valves

86 and 88 are de-energized, the second cam phasing control system 80 performs the same function as the first cam phasing control system 40 when both control

valves

46 and 48 are de-energized. When it is desired to advance the cylinder valve timing, the first control valve 86 remains de-energized, while the second control valve 88 is electrically operated into a position connecting the second workport 97 to the fourth port 98. In this state, pressurized oil from the oil pump 82 is applied to the first actuator port 106 of the cam phase actuator 104 through the first control valve 86. Simultaneously, oil flows out of the second actuator port 108 through the second control valve 88, the fourth check valve 99, and the second regeneration line 102. The oil flowing through the second regeneration line 102 combines with the oil from the pump flowing out of the first work port 93. Therefore, the oil discharged from the second actuator port 108 is supplied to the first actuator port 106 in a regenerative manner, thereby reducing the amount of oil that needs to flow out of the oil pump 82 to operate the cam-phase actuator 104. This hydraulic regeneration reduces the amount of energy consumed by the oil pump 82. Furthermore, in order for the pump to also supply the second cam phasing control system 80, the oil pump 82 does not have to be significantly oversized beyond that required to effectively lubricate the engine.

Likewise, when it is desired to retard cylinder valve timing, the first control valve 86 is energized to a position where the first working port 93 is connected to the second port 94. At the same time, the second control valve 88 remains de-energized to provide a path for pump output oil to pass from the third port 96 to the second work port 97. In this mode of operation, oil discharged from the first actuator port 106 of the cam phase actuator 104 is fed in a regenerative manner through the first control valve 86, the third check valve 95 and the first regeneration line 100 back to the second actuator port 108. The regeneration flow is combined with any additional flow passing through the second control valve 88 to be bled from the oil pump 82 to actuate the cam phase actuator 104.

The second embodiment in fig. 5 can be altered by providing regeneration to only one of the

actuator ports

106 or 108, but not the other. For example, the first regeneration line 100 may be replaced by a line connecting the second port 94 of the first control valve 86 to the reservoir 84. In this variation, the flow exiting the second port 94 is returned to the reservoir 84, while the flow exiting the fourth port 98 of the second control valve 88 remains flowing through the second regeneration line 102 to the first actuator port 106.

As described above, the net torque acting on the camshaft may be used to provide cam phasing in a desired direction. When operating in the torque actuation mode, the cam phasing control system only requires sufficient oil flow to compensate for leakage, and therefore does not substantially affect the pressure in the main oil gallery of the engine. The main oil gallery of the engine, which is typically located in the cylinder block, provides a passage for oil to travel to many major components of the engine, such as crankshaft bearings, cam gear (s)/bearing(s), and crank rod bearings, for example. Thus, a sharp change in pressure in the main oil gallery of an engine may result in insufficient oil delivery to the main components of the engine and cause overheating and/or engine failure.

Referring to fig. 6 and 7, a third embodiment of the control system provides a hybrid cam phasing control system 200, the hybrid cam phasing control system 200 minimizing its effect on the pressure in the main oil gallery of the engine by controlling when the hybrid cam phasing control system 200 operates in either a cam torque actuated mode or an oil pressure actuated mode, as will be described in more detail below. The hybrid cam phasing control system 200 can utilize a dynamic regeneration valve 202, shown in fig. 6, which dynamic regeneration valve 202 enables the hybrid cam phasing control system 200 to switch between a cam torque actuation mode and an oil pressure actuation mode when adjusting cylinder valve timing. The dynamic regeneration valve 202 includes a housing 204 and a valve member 206 disposed within the housing 204. The housing 204 defines a pressure port 208, a regeneration port 210, and a tank port 212. The valve member 206 illustrated in fig. 6 is a spool valve. The valve member 206 is configured to be movable between a first valve member position (fig. 6) in which fluid communication between the regeneration port 210 and the tank port 212 is prevented, and a second valve member position in which fluid communication between the regeneration port 210 and the tank port 212 is provided. A regenerative spring 214 biases the valve member 206 toward the first valve member position. As the pressure at the pressure port 208 increases, the force acting on the bottom surface 216 of the valve member 206 will eventually overcome the force of the regenerative spring 214 and the valve member 206 will move from the first valve member position to the second valve member position.

Referring to fig. 7, in a hybrid cam phasing control system 200, a conventional oil pump 220 supplies fluid from a reservoir 222 (e.g., an engine oil sump) to a first control valve 224, a second control valve 226, and a dynamic regeneration valve 202. The first and

second control valves

224 and 226 are each electro-hydraulic three-way control valves operated by signals from the engine computer 227. The first port 228 of the first control valve 224 is in fluid communication with the outlet of the oil pump 220, and a first check valve 230 is disposed between the outlet of the oil pump 220 and the first port 228. The first check valve 230 only allows oil to flow from the outlet of the oil pump 220 to the first port 228 and prevents oil from flowing in the opposite direction. In another embodiment, the first check valve 230 may be disposed within the first control valve 224, similar to the check valves 50 and 90 described above.

When the first control valve 224 is in the first position illustrated in fig. 7, the first control valve 224 provides fluid communication between the first port 228 and the first workport 232. The first control valve 224 is biased toward the first position by a first spring 234. When the first solenoid actuator 236 is energized by current from the engine computer 227, the first solenoid actuator 236 overcomes the force of the first spring 234 and the first control valve 224 moves into the second position. In the second position, the first control valve 224 provides fluid communication between the first workport 232 and the second port 238. The second port 238 is in fluid communication with the regeneration port 210 of the dynamic regeneration valve 202.

The third port 240 of the second control valve 226 is in fluid communication with the outlet of the oil pump 220, and a second check valve 242 is disposed between the outlet of the oil pump 220 and the third port 240. The second check valve 242 allows only oil to flow from the outlet of the oil pump 220 to the third port 240 and prevents oil from flowing in the opposite direction. In another embodiment, the second check valve 242 may be disposed within the second control valve 226, similar to the

check valves

52 and 91 described above.

When the second control valve 226 is in one position, the second control valve 226 provides fluid communication between the third port 240 and the second workport 244. The second control valve 226 is configured by a second spring 246 toward the one position. When the second solenoid actuator 248 is activated by current from the engine computer 227, the second solenoid actuator 248 overcomes the force of the second spring 246 and the second control valve 226 moves into another position illustrated in fig. 7. In this other position, the second control valve 226 provides fluid communication between the second workport 244 and the fourth port 250. The fourth port 250 is in fluid communication with the regeneration port 210 of the dynamic regeneration valve 202.

With continued reference to fig. 6 and 7, the sensing line 252 provides fluid communication between the pressure port 208 of the dynamic regeneration valve 202 and the outlet of the oil pump 220. When the pressure at the outlet of the oil pump 220 does not provide sufficient force on the bottom surface 216 of the valve member 206 to overcome the force of the regeneration spring 214, the valve member 206 is forced into the first valve member position, and the dynamic regeneration valve 202 prevents fluid communication between the regeneration port 210 and the tank port 212 and thus to the reservoir 222. When the pressure at the outlet of the oil pump 220 reaches a sufficient level, the force acting on the bottom surface 216 of the valve member 206 overcomes the force of the regeneration spring 214 and the valve member 206 moves to the second valve member position illustrated in fig. 7. In the second valve member position, the dynamic regeneration valve 202 provides fluid communication between the regeneration port 210 and the tank port 212 and thus to the reservoir 222.

The hybrid cam phase control system 200 includes a cam phase actuator 254 for changing the rotational relationship between the crankshaft and the camshaft of the engine. Cam phase actuator 254 may be a conventional hydraulic actuator similar to the actuator shown in fig. 1 and 2. Additionally or alternatively, cam phase actuator 254 may be configured to operate similarly to cam phase actuator 68 shown in fig. 4 and described above. The cam phase actuator 254 includes a first actuator port 256 in fluid communication with the first work port 232 and a second actuator port 258 in fluid communication with the second work port 244. The hybrid cam phasing control system 200 also includes a third check valve 260, a fourth check valve 262, and a recirculation line 264. The third check valve 260 prevents fluid communication between the first workport 232 and the recirculation line 264, and also prevents fluid communication between the first actuator port 256 and the recirculation line 264. The fourth check valve 262 prevents fluid communication between the second workport 244 and the recirculation line 264, and also prevents fluid communication between the second actuator port 258 and the recirculation line 264. The recirculation line 264 provides fluid communication between the second port 238 and the second actuator port 258 and between the fourth port 250 and the first actuator port 256.

Operation of the hybrid cam phasing control system 200 will be described with reference to fig. 6-8. It should be appreciated that the following description of advancing and retarding cylinder valve timing is for one rotational direction of the crankshaft, and that the operation of the first and

second control valves

224, 226 would be reversed for the other rotational direction of the crankshaft. Thus, the following description is one non-limiting example of the operation of the hybrid cam phase control system 200.

The hybrid cam phase control system 200 may adjust the cam phase actuator 254 using a cam torque actuation mode or an oil pressure actuation mode. Regardless of whether the hybrid cam phase control system 200 is operating in the cam torque actuation mode or the oil pressure actuation mode, when the cam phase actuator 254 is adjusted to advance or retard cylinder valve timing, the operation of the first and

second control valves

224, 226 will be the same for both modes.

To adjust the cam phase actuator 254 and advance cylinder valve timing, the first solenoid actuator 236 is de-energized such that the first control valve 224 provides fluid communication between the first port 228 and the first workport 232, and the second solenoid actuator 248 is energized such that the second control valve 226 provides fluid communication between the second workport 244 and the fourth port 250. This allows oil to be supplied from the oil pump 220 into the first actuator port 256 and allows additional oil to be drained from the second actuator port 258 back to the reservoir 222.

To adjust the cam phase actuator 254 and retard the cylinder valve timing, the first solenoid actuator 236 is energized such that the first control valve 224 provides fluid communication between the first working port 232 and the second port 238 ahead, and the second solenoid actuator 248 is de-energized such that the second control valve 226 provides fluid communication between the third port 240 and the second working port 244. This allows oil to be supplied from the oil pump 220 into the second actuator port 258 and allows additional oil to be drained from the first actuator port 256 back to the reservoir 222.

Switching between the cam torque actuation mode and the oil pressure actuation mode is managed by the pressure at the outlet of the oil pump 220. When the pressure at the outlet of the oil pump 220, as sensed by sense line 252, provides a force on the bottom surface 216 of the valve member 206 that overcomes the force of the regeneration spring 214, the hybrid cam phasing control system 200 will operate in an oil pressure actuated mode and the pressurized oil provided by the oil pump 220 will adjust the cam phasing actuator 254. In the oil pressure actuated mode, valve member 206 is forced into the second valve member position and oil flowing from either the first workport 238 or the second workport 250 (depending on whether the cylinder valve timing is being advanced or retarded) is allowed to flow through the dynamic regeneration valve 202 to the reservoir 222. For example, when the cam phase actuator 254 is adjusted to advance the cylinder valve timing, pressurized oil is supplied from the pump 220 through the first control valve 224 to the first actuator port 256. Oil discharged from the second actuator port 258 is supplied to the reservoir 222 through the second control valve 226 and the dynamic regeneration valve 202, as shown in bold lines in fig. 7.

When the pressure at the outlet of the oil pump 220, as sensed by sense line 252, does not provide enough force on the bottom surface 216 of the valve member 206 to overcome the force of the regeneration spring 214, the hybrid cam phasing control system 200 will operate in a cam torque actuation mode and the net force acting on the camshaft will be used to adjust the cam phasing actuator 254. In the cam torque actuation mode, the biasing valve member 206 enters the first valve member position and oil is recirculated through the hybrid cam phasing control system 200. For example, when the net torque on the camshaft adjusts the cam phase actuator 254 to advance cylinder valve timing, oil from the oil pump 220 may be supplied into the first actuator port 256, and oil discharged from the second actuator port 258 is supplied through the second control valve 226, the recirculation line 264, and the third check valve 260, as shown in bold lines in fig. 8. Oil flowing through the recirculation line 264 and the third check valve 260 is fed back to the first actuator port 256. Thus, oil discharged from the second actuator port 258 is recirculated to the first actuator port 256, and the oil pump 220 only needs to supply enough oil to the first port 228 to compensate for the leakage. This minimizes the effect of hybrid cam phase control system 200 on the pressure in reservoir 222 and enables adjustment of cam phase actuator 254 at low oil pump pressure.

If the engine has dual camshafts, a second cam phase actuator 266 is provided for the other camshaft, as shown in FIG. 9. The second cam phase actuator 266 includes one actuator port 268 in fluid communication with the first workport 232 and another actuator port 270 in fluid communication with the second workport 244. In this embodiment,

cam phase actuators

254 and 266 may be designed similarly to

cam phase actuators

68 and 72 described above. For example, the cam phase actuator 254 may be designed such that the first and

second actuator ports

256 and 258 may be in fluid communication with the first and

second passages

30 and 33 when the camshaft is rotationally positioned between 0 and 90 degrees. Further, the second cam phase actuator may be designed such that the

actuator ports

268 and 270 may be in fluid communication with the first and

second passages

30 and 33 when the camshaft is rotationally positioned between 180 and 270 degrees. One skilled in the art will recognize that other angles and ranges of angles may be used to control two or more cam phase actuators.

Referring to fig. 10 and 11, a fourth embodiment of the control system provides a hybrid cam phasing control system 300, the hybrid cam phasing control system 300 minimizing its effect on the pressure in the main oil gallery of the engine by controlling when the hybrid cam phasing control system 300 operates in either a cam torque actuated mode or an oil pressure actuated mode, as will be described in more detail below. The hybrid cam phasing control system 300 may utilize a dynamic regeneration valve 302 shown in fig. 10, which dynamic regeneration valve 302 enables the hybrid cam phasing control system 300 to switch between a cam torque actuation mode and an oil pressure actuation mode when adjusting cylinder valve timing. The dynamic regeneration valve 302 includes a housing 304 and a valve member 306 disposed within the housing 304. The housing 304 defines a pressure port 308, a regeneration port 310, and a tank port 312. The valve member 306 illustrated in fig. 11 is a poppet valve. The valve member 306 is configured to be movable between a first valve member position (fig. 11) in which fluid communication between the regeneration port 310 and the tank port 312 is prevented, and a second valve member position in which fluid communication between the regeneration port 310 and the tank port 312 is provided. The regeneration spring 314 biases the valve member 306 toward the first valve member position. Valve member 306 includes a lower surface 316 in fluid communication with pressure port 308 and a central portion 318 in fluid communication with regeneration port 310. The central portion 318 defines a differential area 319. As the pressure at the pressure port 308 increases, the force acting on the bottom surface 316 of the valve member 306 will eventually overcome the force of the regenerative spring 314 and the valve member 306 will move from the first valve member position to the second valve member position.

Referring to fig. 11, in a hybrid cam phasing control system 300, a conventional oil pump 320 supplies fluid from a reservoir 322 (e.g., an engine oil sump) to a first control valve 324, a second control valve 326, and a dynamic regeneration valve 302. The first control valve 324 and the second control valve 326 are each electro-hydraulic three-way control valves operated by signals from an engine computer 327. The first port 328 of the first control valve 324 is in fluid communication with the outlet of the oil pump 320, and a first check valve 330 is disposed between the outlet of the oil pump 320 and the first port 328. The first check valve 330 only allows oil to flow from the outlet of the oil pump 320 to the first port 328 and prevents oil from flowing in the opposite direction. In another embodiment, the first check valve 330 may be disposed within the first control valve 324, similar to the check valves 50 and 90 described above.

When the first control valve 324 is in the first position illustrated in fig. 11, the first control valve 324 provides fluid communication between the first port 328 and the first workport 332. The first control valve 324 is biased toward the first position by a first spring 334. When the first solenoid actuator 336 is energized by current from the engine computer 327, the first solenoid actuator 336 overcomes the force of the first spring 334 and the first control valve 324 moves into the second position. In the second position, the first control valve 324 provides fluid communication between the first workport 332 and before the second port 338. The second port 338 is in fluid communication with the regeneration port 310 of the dynamic regeneration valve 302.

The third port 340 of the second control valve 326 is in fluid communication with the outlet of the oil pump 320, and a second check valve 342 is disposed between the outlet of the oil pump 320 and the third port 340. The second check valve 342 allows only oil to flow from the outlet of the oil pump 320 to the third port 340 and prevents oil from flowing in the opposite direction. In another embodiment, a second check valve 342 may be disposed within the second control valve 326, similar to the

check valves

52 and 91 described above.

When the second control valve 326 is in one position, the second control valve 326 provides fluid communication between the third port 340 and the second workport 344. The second control valve 326 is configured by a second spring 346 toward the one position. When the second solenoid actuator 348 is activated by current from the engine computer 327, the second solenoid actuator 348 overcomes the force of the second spring 346 and the second control valve 326 moves into another position illustrated in fig. 11. In this other position, the second control valve 326 provides fluid communication between the second workport 344 and the fourth port 350. The fourth port 350 is in fluid communication with the regeneration port 310 of the dynamic regeneration valve 302.

With continued reference to fig. 10 and 11, the sensing line 352 provides fluid communication between the pressure port 308 of the dynamic regeneration valve 302 and the outlet of the oil pump 320. When the pressure at the outlet of the oil pump 320 does not provide sufficient force on the bottom surface 316 of the valve member 306 to overcome the force of the regeneration spring 314, the valve member 306 is forced into the first valve member position, and the dynamic regeneration valve 302 prevents fluid communication between the regeneration port 310 and the tank port 312 and thus to the reservoir 322. When the pressure at the outlet of the oil pump 320 reaches a sufficient level, the force acting on the bottom surface 316 of the valve member 306 overcomes the force of the regenerative spring 314 and the valve member 306 moves to the second valve member position illustrated in fig. 11. In the second valve member position, the dynamic regeneration valve 302 provides fluid communication between the regeneration port 310 and the tank port 312 and thus to the reservoir 322.

The hybrid cam phase control system 300 includes a cam phase actuator 354 for changing the rotational relationship between the crankshaft and the camshaft of the engine. The cam phase actuator 354 may be a conventional hydraulic actuator similar to the actuator shown in fig. 1 and 2. Additionally or alternatively, the cam phase actuator 354 may be configured to operate similarly to the cam phase actuator 68 shown in fig. 4 and described above. Cam phase actuator 354 includes a first actuator port 356 in fluid communication with first work port 332 and a second actuator port 358 in fluid communication with second work port 344. The hybrid cam phasing control system 300 further includes a third check valve 360, a fourth check valve 362, and a recirculation line 364. The third check valve 360 prevents fluid communication between the first workport 332 and the recirculation line 364, and also prevents fluid communication between the first actuator port 356 and the recirculation line 364. The fourth check valve 362 prevents fluid communication between the second workport 344 and the recirculation line 364, and also prevents fluid communication between the second actuator port 358 and the recirculation line 364. A recirculation line 364 provides fluid communication between the second port 338 and the second actuator port 358, and provides fluid communication between the fourth port 350 and the first actuator port 356.

The operation of the hybrid cam phase control system 300 will be described with reference to fig. 10-13. It should be appreciated that the following description of advancing and retarding cylinder valve timing is for one rotational direction of the crankshaft, and that the operation of the first control valve 324 and the second control valve 326 will be reversed for the other rotational direction of the crankshaft. Thus, the following description is one non-limiting example of the operation of the hybrid cam phase control system 300.

The hybrid cam phase control system 300 may adjust the cam phase actuator 354 using either a cam torque actuation mode or an oil pressure actuation mode. Regardless of whether the hybrid cam phase control system 300 is operating in the cam torque actuation mode or the oil pressure actuation mode, when the cam phase actuator 354 is adjusted to advance or retard cylinder valve timing, the operation of the first control valve 324 and the second control valve 326 will be the same for both modes.

To adjust the cam phase actuator 354 and advance cylinder valve timing, the first solenoid actuator 336 is de-energized such that the first control valve 324 provides fluid communication between the first work port 328 and the first work port 332, and the second solenoid actuator 348 is energized such that the second control valve 326 provides fluid communication between the second work port 344 and the fourth port 350. This allows oil to be supplied from the oil pump 320 into the first actuator port 356 and allows additional oil to drain from the second actuator port 358 back to the reservoir 322.

To adjust the cam phase actuator 354 and retard cylinder valve timing, the first solenoid actuator 336 is energized such that the first control valve 324 provides fluid communication between the first working port 332 and the second port 338, and the second solenoid actuator 348 is de-energized such that the second control valve 326 provides fluid communication between the third port 340 and the second working port 344. This allows oil to be supplied from the oil pump 320 into the second actuator port 358 and allows additional oil to drain from the first actuator port 356 back to the reservoir 322.

Switching between the cam torque actuation mode and the oil pressure actuation mode is managed by the pressure at the outlet of the oil pump 320. When the pressure at the outlet of the oil pump 320, as sensed by sense line 352, provides a force on the bottom surface 316 of the valve member 306 that overcomes the force of the regeneration spring 314, the hybrid cam phasing control system 300 will operate in an oil pressure actuated mode and the pressurized oil provided by the oil pump 320 will be used to adjust the cam phasing actuator 354. In the oil pressure actuated mode, the valve member 306 is forced into the second valve member position and oil flowing from either the first workport 338 or the second workport 350 (depending on whether the cylinder valve timing is being advanced or retarded) is allowed to flow through the dynamic regeneration valve 302 to the reservoir 322. For example, when the cam phase actuator 354 is adjusted to advance the cylinder valve timing, pressurized oil is supplied from the pump 320 through the first control valve 324 to the first actuator port 356. Oil discharged from the second actuator port 358 is supplied to the reservoir 322 through the second control valve 326 and the dynamic regeneration valve 302, as shown in bold lines in fig. 11.

As described above, when the hybrid cam phasing control system 300 is operating in an oil pressure assisted mode, the valve member 306 is in the second valve member position. During this operation, the differential area 319 defined by the central portion 318 of the valve member 306 enables the valve member 306 to increase or decrease the flow area between the regeneration port 310 and the tank port 312 in response to the pressure at the regeneration port 310. For example, if there is a spike in pressure at the regeneration port 310, the illustrated differential area 319 enables the valve member 306 to increase the flow area between the regeneration port 310 and the tank port 312 as the valve member 306 lifts in response to the pressure spike. This function of valve member 306 is illustrated in fig. 11-14 by regeneration sensing line 365. Specifically, fig. 12 illustrates the above example in bold lines, where the hybrid cam phasing control system 300 is operating in an oil pressure actuated mode, and the pressure at the regeneration port 310 further forces the valve member 306 to rise and increase the flow area between the regeneration port 310 and the tank port 312.

Those skilled in the art will recognize that the differential region 319 may be designed to provide additional flow area between the regeneration port 310 and the tank port 312 during peaks in pressure at the regeneration port 310, or additional closing of the flow area between the regeneration port 310 and the tank port 312 during peaks in pressure at the regeneration port 310, as compared to the differential region 319 shown in fig. 10. Thus, the differential area 319 can be designed to reduce the resistance of the hydraulic circuit shown in FIGS. 11-14 and provide a faster transfer rate by providing additional flow area. Alternatively, the differential area 319 may be designed to ensure that if a constant pressure spike at the regeneration port 310 ceases to occur, the hybrid cam phase control system 300 will default to the oil pressure actuated mode.

When the pressure at the outlet of the oil pump 320, as sensed by sense line 352, does not provide enough force on the bottom surface 316 of the valve member 306 to overcome the force of the regeneration spring 314, the hybrid cam phasing control system 300 will operate in a cam torque actuation mode and the net force acting on the camshaft will be used to adjust the cam phasing actuator 354. In the cam torque actuation mode, the biasing valve member 306 enters the first valve member position and oil recirculates through the hybrid cam phasing control system 300. For example, when the net torque on the camshaft adjusts the cam phase actuator 354 to advance cylinder valve timing, oil from the oil pump 320 may be supplied into the first actuator port 356, and oil discharged from the second actuator port 358 is supplied through the second control valve 326, the recirculation line 364, and the third check valve 360, as shown in bold lines in fig. 13. Oil flowing through the recirculation line 364 and the third check valve 360 is fed back to the first actuator port 356. Thus, oil discharged from the second actuator port 358 is recirculated to the first actuator port 356, and the oil pump 320 only needs to supply enough oil to the first port 328 to compensate for the leakage. This minimizes the effect of the hybrid cam phase control system 300 on the pressure in the reservoir 322 and enables adjustment of the cam phase actuator 354 at low oil pump pressures.

If the engine has dual camshafts, a second cam phase actuator 366 is provided for the other camshaft, as shown in FIG. 14. The second cam phase actuator 366 includes one actuator port 368 in fluid communication with the first work port 332 and another actuator port 370 in fluid communication with the second work port 344. In this embodiment, the

cam phase actuators

354 and 366 may be designed similarly to the

cam phase actuators

68 and 72 described above. For example, the cam phase actuator 354 may be designed such that the first and

second actuator ports

356 and 358 may be in fluid communication with the first and

second passages

30 and 33 when the camshaft is rotationally positioned between 0 and 90 degrees. Further, the second cam phase actuator may be designed such that the actuator ports 368 and 370 may be in fluid communication with the first and

second passages

The foregoing description has been directed primarily to one or more embodiments of the invention. While various alternatives are contemplated as being within the scope of the invention, it is expected that one skilled in the art will likely realize additional alternatives that are apparent from disclosure of embodiments of the invention. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing disclosure.

Claims

1. A control system for varying cylinder valve timing of an internal combustion engine, the internal combustion engine comprising a pump, a reservoir, a crankshaft, and a camshaft; the control system includes:

a cam phase actuator for adjusting a rotational phase of the camshaft relative to the crankshaft and having a first actuator port and a second actuator port;

a first control valve including a first port operatively connected to receive fluid from the pump, a second port, and a first workport in fluid communication with the first port of the cam phase actuator, the first control valve having a first position in which fluid communication between the first port and the first workport is provided and having a second position in which fluid communication between the second port and the first workport is provided;

a second control valve including a third port operatively connected to receive fluid from the pump, a fourth port, and a second workport in fluid communication with the second actuator port, the second control valve having one position providing fluid communication between the third port and the second workport and another position providing fluid communication between the fourth port and the second workport; and

a dynamic regeneration valve including a housing and a valve member received within the housing and movable between a first valve member position and a second valve member position, the housing defining a pressure port, a regeneration port, and a tank port, wherein the dynamic regeneration valve is configured to enable the cam phase actuator to switch between operating in an oil pressure actuated mode and a cam torque actuated mode when adjusting the rotational phase of the camshaft relative to the crankshaft.

2. The control system of claim 1, wherein the valve member is in the first valve member position that prevents fluid communication between the regeneration port and the tank port when the cam phase actuator is operating in the cam torque actuated mode.

3. The control system of claim 1, wherein the valve member is in the second valve member position providing fluid communication between the regeneration port and the tank port when the cam phase actuator is operating in the oil pressure actuated mode.

4. The control system of claim 1, wherein the valve member is a spool valve.

5. The control system of claim 1, wherein the valve member is a poppet valve.

6. The control system of claim 1, wherein the valve member includes a portion defining a differential area.

7. The control system of claim 6, wherein the differential area enables the valve member to increase or decrease a flow area between the regeneration port and the tank port when the valve member is in the second valve member position.

8. The control system of claim 1, further comprising a first check valve operably connected to restrict fluid flow only in a direction from the pump to the first port.

9. The control system of claim 8, further comprising a second check valve operably connected to restrict fluid flow only in a direction from the pump to the third port.

10. The control system of claim 1, wherein the second port of the first control valve is in fluid communication with the second actuator port.

11. The control system of claim 10, further comprising a third check valve operably connected to restrict fluid flow only in a direction from the second port of the first control valve to the second actuator port.

12. The control system of claim 1, wherein the fourth port of the second control valve is in fluid communication with the first actuator port.

13. The control system of claim 12, further comprising a fourth check valve operably connected to restrict fluid flow only in a direction from the fourth port of the second control valve to the first actuator port.

14. The control system of claim 1, wherein the second port of the first control valve and the fourth port of the second control valve are in fluid communication with the regeneration port.

15. The control system of claim 1, wherein the tank port is in fluid communication with the reservoir.

16. The control system of claim 1, wherein the pressure port is in fluid communication with an outlet of the pump.

17. The control system of claim 1, wherein the valve member is biased into the first valve member position by a spring.

18. The control system of claim 1, wherein the first control valve and the second control valve are both three-way valves.

19. The control system of claim 1, wherein the cam phase actuator is a first cam phase actuator, and further comprising a second cam phase actuator having one actuator port in fluid communication with the first work port and another actuator port in fluid communication with the second work port, wherein phasing of the first cam phase actuator is varied over a first range of angles during rotation of the camshaft and phasing of the second cam phase actuator is varied over a second range of angles during rotation of the camshaft.

20. A control system for varying cylinder valve timing of an internal combustion engine, the internal combustion engine comprising a pump, a reservoir, a crankshaft, and a camshaft; the control system includes:

a dynamic regeneration valve configured to switch operation of the cam phase actuator between an oil pressure actuation mode and a cam torque actuation mode based on a pressure at an outlet of the pump.

21. The control system of claim 20, wherein the dynamic regeneration valve includes a housing and a valve member received within the housing and movable between a first valve member position and a second valve member position, the housing defining a pressure port, a regeneration port, and a tank port.

22. The control system of claim 21, wherein fluid communication between the regeneration port and the tank port is prevented when the valve member is in the first valve member position.

23. The control system of claim 21, wherein fluid communication between the regeneration port and the tank port is provided when the valve member is in the second valve member position.

24. The control system of claim 21, wherein the valve member is biased toward the first valve member position by a biasing member.

25. The control system of claim 24, wherein the biasing member is a spring.

26. The control system of claim 24, wherein the pressure at the outlet of the pump does not provide sufficient force on the valve member to overcome the force of the biasing member and the valve member is biased by the biasing member toward the first valve member position when the cam phase actuator is operating in the cam torque actuation mode.

27. The control system of claim 24 wherein when said cam phase actuator is operating in said oil pressure actuated mode, said pressure at said outlet of said pump provides sufficient force on said valve member to overcome the force of said biasing member and said valve member moves to said second valve member position.

28. The control system of claim 21, wherein the valve member includes a portion defining a differential area.

29. The control system of claim 28, wherein the differential area enables the valve member to increase or decrease a flow area between the regeneration port and the tank port in response to a change in the pressure at the outlet of the pump and/or a change in pressure at the regeneration port when the valve member is in the second valve member position.

30. The control system of claim 20, further comprising a first check valve operably connected to restrict fluid flow only in a direction from the pump to the first port.

31. The control system of claim 30, further comprising a second check valve operably connected to restrict fluid flow only in a direction from the pump to the third port.

32. The control system of claim 20, wherein the second port of the first control valve is in fluid communication with the second actuator port.

33. The control system of claim 32, further comprising a third check valve operably connected to restrict fluid flow only in a direction from the second port of the first control valve to the second actuator port.

34. The control system of claim 20, wherein the fourth port of the second control valve is in fluid communication with the first actuator port.

35. The control system of claim 34, further comprising a fourth check valve operably connected to restrict fluid flow only in a direction from the fourth port of the second control valve to the first actuator port.

36. The control system of claim 21, wherein the second port of the first control valve and the fourth port of the second control valve are in fluid communication with the regeneration port.

37. The control system of claim 21, wherein the tank port is in fluid communication with the reservoir.

38. The control system of claim 21, wherein the pressure port is in fluid communication with an outlet of the pump.

39. The control system of claim 20, wherein the first control valve and the second control valve are both three-way valves.

40. The control system of claim 20, wherein the cam phase actuator is a first cam phase actuator, and further comprising a second cam phase actuator having one actuator port in fluid communication with the first work port and another actuator port in fluid communication with the second work port, wherein phasing of the first cam phase actuator is varied over a first range of angles during rotation of the camshaft and phasing of the second cam phase actuator is varied over a second range of angles during rotation of the camshaft.

41. A control system for varying cylinder valve timing of an internal combustion engine, the internal combustion engine comprising a pump, a reservoir, a crankshaft, and a camshaft; the control system includes:

at least one control valve comprising at least two ports, the at least one control valve selectively providing fluid communication between one or more of the pump and the first actuator port, the pump and the second actuator port, the first actuator port and the reservoir, and the second actuator port and the reservoir; and

a dynamic regeneration valve disposed between one of the at least two ports and the reservoir, wherein the dynamic regeneration valve is configured to switch operation of the cam phase actuator between an oil pressure actuation mode and a cam torque actuation mode based on a pressure at an outlet of the pump.