Patent Grant
8746279
The present invention relates to on/off fluid control valves; and more particularly, to such valves as are commonly employed for switching two-step mechanisms in the valve train system of internal combustion engines; and most particularly, to on/off fluid control valves which improve the response time of the two-step mechanisms by priming the on/off fluid control valve and oil galleries.
On/off fluid control valves for controllably diverting the flow of fluids are well known which include a supply port, a control port, and a vent port. In a typical on/off fluid control valve, a valve member, for example a ball, is selectively seated and unseated from a valve seat for respectively preventing and allowing a high pressure working fluid from reaching a working device. In a high pressure mode of operation, a solenoid of the on/off fluid control valve axially positions a plunger to urge the ball to be unseated from the valve seat. In this way, high pressure working fluid from the supply port is communicated to the working device through the control port and working fluid is prevented from exiting the on/off fluid control valve through the vent port. In a venting mode of operation, the plunger is positioned axially to allow high pressure working fluid to seat the ball against the valve seat and to allow working fluid to pass from the control port to the vent port. In this way, high pressure working fluid is prevented from being communicated to the working device and working fluid is vented from the working device through the vent port.
A common usage for an on/off fluid control valve is to variably actuate engine control subsystems such as camshaft phasers and multi-step or valve deactivation mechanisms. In a two step valve mechanism, for example, the mechanism selects the engine intake valve lift profile (low or high) of an intake valve camshaft using a hydraulically activated roller finger follower (RFF).
In a simple configuration of this example, the on/off fluid control valve supplies high pressure oil, typically from an engine-driven oil pump, to activate the RFF, and shuts off the oil supply to deactivate and vent oil from the RFF. However, when the on/off fluid control valve is in the venting mode of operation for a sufficient amount of time, oil may vent from the on/off fluid control valve and an oil gallery leading from the control port to the RFF. This may lead to air taking the place previously occupied by oil. Consequently, when the on/off fluid control valve is placed in the high pressure mode of operation, a delay may take place in allowing pressurized oil from reaching the RFF because the air must first be purged.
What is needed is an on/off fluid control valve which keeps fluid passages free of air when the on/off fluid control valve is placed in the venting mode of operation.
Briefly described, a valve assembly is provided for receiving a working fluid from a working fluid source and then communicating the working fluid to and from a working that is switchable between a first mode of operation to a second mode of operation at a predetermined pressure of the working fluid. The valve assembly includes a housing with a housing control bore, a supply port in selective fluid communication with the housing control bore for receiving working fluid from the working fluid source, a control port in fluid communication with the housing control bore for communicating the working fluid to and from the working device, and a vent port in fluid communication with the housing control bore for selectively returning the working fluid to the working fluid source. A valve seat assembly is disposed within the housing control bore and includes a supply valve seat. A supply valve member is selectively seated and unseat with the supply valve seat such that working fluid is passed through the valve seat assembly to the control port at or above the predetermined pressure when the supply valve member is not seated with the supply valve seat and such that the working fluid is not passed through the valve seat assembly to the control port at or above the predetermined pressure when the supply valve member is seated with the supply valve seat. A bleed orifice is provided for communicating the working fluid from the supply port to the control port at a second pressure that is less than the predetermined pressure when the supply valve member is seated with the supply valve seat.
This invention will be further described with reference to the accompanying drawings in which:
In accordance with a preferred embodiment of this invention and referring to
Still referring to
Valve seat assembly 30 is disposed within housing control bore 24. Valve seat assembly 30 may be preferably made of plastic, but may alternatively be made of metal. Valve seat assembly 30 includes smaller diameter section 32 which is sized to be smaller in diameter than housing control bore 24. Valve seat assembly 30 also includes larger diameter section 34 which extends radially outward from smaller diameter section 32 and which is sized to be press fit within housing control bore 24 to substantially prevent working fluid from passing between the interface of housing control bore 24 and larger diameter section 34 by circumferentially sealing with housing control bore 24. An insignificant amount of working fluid that does not affect the operation of valve assembly 10 or working device 21 may pass between the interface of housing control bore 24 and larger diameter section 34 while still being considered to substantially prevent working fluid from passing between the interface of housing control bore 24 and larger diameter section 34. Larger diameter section 34 is positioned axially between exhaust port 20 and the bottom of housing control bore 24. Annular control chamber 36 is defined radially between smaller diameter section 32 and housing control bore 24 and axially between larger diameter section 34 and the bottom of housing control bore 24. Housing control/vent passage 28 provides fluid communication between annular control chamber 36 and control port 18.
Valve seat assembly 30 includes valve seat assembly bore 38 which extends axially part way into smaller diameter section 32 and which is terminated by conical supply valve seat 40. Valve seat control/exhaust passages 42 extend radially through valve seat assembly 30 axially between large diameter section 34 and conical supply valve seat 40 and are in fluid communication with valve seat assembly bore 38 through valve seat supply passage 44 which is coaxial with conical supply valve seat 40. Valve seat control/vent passages 42 provide fluid communication from valve seat supply passage 44 to annular control chamber 36. Valve seat assembly 30 also includes valve seat vent passage 46 which extends axially through larger diameter section 34 to provide fluid communication from valve seat control/vent passages 42 to exhaust port 20. Valve seat vent passage 46 may be coaxial with conical supply valve seat 40.
The end of smaller diameter section 32 distal from larger diameter section 34 is sealed against housing 22. This may be accomplished by providing housing 22 with raised annular ring 48 which extends axially away from the bottom of housing control bore 24. Raised annular ring 48 radially surrounds housing supply passage 26 and is located radially between housing supply passage 26 and housing control/vent passage 28. Raised annular ring 48 may be sized to interface with valve seat assembly bore 38 with a press fit such to substantially prevent working fluid passing between the interface of valve seat assembly bore 38 and raised annular ring 48. An insignificant amount of working fluid that does not affect the operation of valve assembly 10 or working device 21 may pass between the interface of raised annular ring 48 and valve seat assembly bore 38 still being considered to substantially prevent working fluid from passing between the interface of raised annular ring 48 and valve seat assembly bore 38. Alternatively, but not shown, raised annular ring 48 may be eliminated, and the sealing function between smaller diameter section 32 and housing 22 may be accomplished by bonding the axial end of smaller diameter section 32 distal from larger diameter section 34 to the bottom of housing control bore 24. Bonding may be accomplished, for example, by adhesives or welding.
A supply valve member, shown as ball 50, is disposed within valve seat assembly bore 38 axially between conical supply valve seat 40 and the bottom of housing control bore 24. Ball 50 is selectively seated and selectively unseated from conical supply valve seat 40 for respectively preventing and permitting fluid communication from supply port 16 to annular control chamber 36 through valve seat supply passage 44. Seating and unseating of ball 50 from conical supply valve seat 40 will be described in more detail later.
The axial end of larger diameter section 34 distal from smaller diameter section 32 defines vent valve seat 52. Vent valve seat 52 will be discussed in more detail later in the operation of valve assembly 10.
Bleed orifice 54 extends axially through housing 22 from supply port 16 to control port 18. Bleed orifice 54 is sized sufficiently small to produce a pressure differential between supply port 16 and control port 18. In this way, working fluid is supplied to control port 18 even when ball 50 is seated on conical supply valve seat 40. However, due to the pressure differential created by bleed orifice 54, the working fluid supplied to control port 18 through bleed orifice 54 is less than the predetermined pressure needed to cause working device 21 to switch from the first mode of operation to the second mode of operation. Working fluid that enters control port 18 through bleed orifice 54 when ball 50 is seated on conical supply valve seat 40 (
Actuator section 14 includes solenoid 60 having coil 62 and axially moveable armature 64 located coaxially within coil 62. Armature 64 is fixed to plunger 66 such that axial movement of armature 64 results in axial movement of plunger 66 between a high pressure position and a vent position. Guide bushing 68 includes guide bushing solenoid end 70 which is fixed coaxially within coil 62. Guide bushing solenoid end 70 is a magnetic pole which is part of the magnetic circuit of solenoid 60. Guide bushing 68 also includes guide bushing hydraulic end 72 which is fixed coaxially within housing control bore 24. Guide bushing bore 74 extends axially through guide bushing 68 coaxial with coil 62 and housing control bore 24 to closely guide plunger 66, thereby substantially preventing radial movement of plunger 66.
Solenoid 60 also includes return spring 76 which is located partly within spring pocket 78 of guide bushing 68. Spring pocket 78 extends axially part way into guide bushing solenoid end 70 coaxial with guide bushing bore 74. Return spring 76 biases armature 64 away from guide bushing 68.
When coil 62 is energized with an electric current, a magnetic field is generated resulting in an attractive force between armature 64 and guide bushing 68. Consequently, armature 64 is moved axially toward guide bushing 68, thereby compressing return spring 76. Conversely, when coil 62 is not energized with an electric current, armature 64 is moved axially away from guide bushing 68 by the force of return spring 76. Solenoids and their operation are well known to those skilled in the art and will not be further discussed herein.
Plunger 66 extends axially through guide bushing bore 74 and into housing control bore 24. Plunger 66 includes vent valve member 80 which extends radially outward from plunger 66. Vent valve member 80 is located axially between guide bushing 68 and valve seat assembly 30. Plunger 66 also includes a supply valve actuation section shown as ball actuation section 82 which extends axially away from vent valve member 80 toward valve seat assembly 30 and which extends axially through valve seat vent passage 46 and axially into valve seat supply passage 44. Ball actuation section 82 is sized to provide radial clearance between valve seat vent passage 46 and valve seat supply passage 44 to allow working fluid to flow between ball actuation section 82 and valve seat vent passage 46 and between ball actuation section 82 and valve seat supply passage 44.
Exhaust valve shoulder 84 is the surface of plunger 66 connecting vent valve member 80 to ball actuation section 82. Exhaust valve shoulder 84 may be substantially parallel to vent valve seat 52. Exhaust valve shoulder 84 will be discussed in more detail later in the operation of valve assembly 10.
In operation and referring to
In operation and referring to
While this invention has been described in terms of preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow.
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