Patent Application
20120272932
The present disclosure relates to a fluid pressure control valve.
A valve is a device that regulates the flow of a fluid by opening, closing, or partially obstructing various passageways. Some valves are operated manually, while others are configured to operate automatically in response to changing conditions with the subject fluid passage. Valves may be used in complex automatic control systems and may require an actuator, such as a solenoid, to actuate a particular valve based on an external input.
Valves are employed in a multitude of industries and are often used to regulate flows of various fluids in motor vehicles. In vehicle internal combustion engines, valves are commonly employed for regulating flows of coolant and oil. For example, valves may be used to control the engine's valve train by regulating a supply of pressurized oil to the engine's hydraulic lash adjusters.
A valve assembly configured to provide feed-back control of pressurized fluid in a gallery includes a housing and a pressure chamber. The valve assembly also includes a first passage configured to provide continuous flow of fluid through the gallery and a second passage configured to supply the pressurized fluid from an external source to the gallery. The valve assembly additionally includes a piston configured to move or shift within the pressure chamber between a first position and a second position and having a third passage configured to establish fluid communication between the first passage and the pressure chamber. The first position of the piston opens the second passage and the second position of the piston closes the second passage. Furthermore, the valve assembly includes a spring disposed between the piston and the housing. The spring is configured to move the piston to the first position when pressure of the fluid in the gallery is less than a threshold fluid pressure value. The spring is also configured to permit the piston to shift to the second position when pressure of the fluid in the gallery is equal to or greater than the threshold fluid pressure value.
The pressure chamber may include a reaction surface configured to generate a hydraulic force sufficient to overcome the spring and shift the piston to the second position when the fluid pressure is at or above the threshold fluid pressure value.
The valve assembly may also include a cap assembled onto the housing. The reaction surface may then be arranged on the cap.
The third passage may be arranged substantially perpendicular to the first passage.
The valve assembly may additionally include a fourth passage configured to purge fluid that escapes from the pressure chamber past the piston.
The third passage may include an orifice configured to establish a rate of movement of the piston within the pressure chamber in response to fluid pressure changes in the gallery.
The external source supplying pressurized fluid to the gallery may be a fluid pump.
The gallery may be arranged in an internal combustion engine of a vehicle. In such a case, the fluid may be engine oil, and the gallery may then be configured to supply the oil to a hydraulic lash adjuster in a valve train system of the engine.
The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.
Referring to the drawings, wherein like reference numbers refer to like components,
The engine 10 includes cylinders 18 and a valve train system 20 configured to open and close an entryway for air or a fuel/air mixture into the cylinders. As shown, the valve train system 20 includes a camshaft 22 and rocker arms 24 configured to actuate intake valves 26 and a camshaft 23 configured to actuate exhaust valves 28 for controlling intake, compression, ignition, and exhaust cycles of the engine 12. The valve train system 20 also includes hydraulic lash adjusters 30 configured to control clearances in the valve train system 20. Each individual lash adjuster 30 controls the clearance between a particular valve actuating lobe 31 of camshaft 22 or 23, a respective rocker arm 24, and either the intake valve 26 or the exhaust valve 28.
As shown in
As shown in
The piston 46 additionally includes a second narrowed section 58 that generates a second passage 60 between the pump 32 and the gallery 38. Consequently, the second passage 60 is configured to supply the pressurized oil 34 from the pump 32 to the gallery 38. The first narrowed section 54 of the piston 46 includes a channel 62 that is fluidly connected to a third passage 64. Accordingly, the third passage 64 is configured to establish fluid communication between the first passage 56 and the pressure chamber 52. As shown, the third passage 64 is arranged substantially perpendicular to the first passage 56 such that the oil flow exiting the third passage 64 into the pressure chamber 52 is directed toward the cap 44.
The piston 46 is configured to move or shift relative to the housing 42 and within the pressure chamber 52 between a first position 66 (shown in
The threshold oil pressure value is indicative of the magnitude of oil pressure which, if exceeded, may “over-pump” the lash adjusters 30 and eliminate all valve train clearances. Such over-pumping of the lash adjusters 30 may result in excessive preloading of the valve actuating lobes 31 against the respective rocker arms 24 and the valves 26, 28. Additionally, exceeding the threshold oil pressure value may result in increased rate of oil leakage that is generally detrimental to efficiency of the engine's lubrication system. The threshold oil pressure value may be predetermined or established based on requirements of a specific engine configuration. In a particular embodiment, the threshold oil pressure may be set at 60 Psi, or approximately 4 Bar.
With continued reference to
During operation of the engine 12, the valve assembly 40 facilitates a continuous flow of oil to traverse the gallery 38 in order to pressurize lash adjusters 30 without interruption. Simultaneously, the valve assembly 40 is fed by the pressurized oil 34 from the pump 32 via the main gallery 36 to an oil gallery 38. Due to the operation of the pump 32, the pressurized oil 34 is primary delivered to the main gallery 36, and the oil pressure inside the main gallery initially exceeds the pressure of the oil in the gallery 38. As the pressure of the oil in the gallery 38 remains lower than the threshold oil pressure value, the piston 46 stays in the first position 66 and permits the pressurized oil 34 to be supplied into the gallery 38. As the pressurized oil 34 continues to be added to the gallery 38, the pressure inside the gallery will rise and is likely to eventually reach the threshold oil pressure value. As the pressure of the oil in the gallery 38 is increased, the pressure is also increased inside the pressure chamber 52 due to the oil from the gallery being supplied to the chamber via the third passage 64.
When the oil pressure reaches the predetermined oil pressure value the hydraulic force generated inside the pressure chamber 52 exceeds the force provided by the spring 48, and the piston 46 shifts to the second position 68. When the piston shifts to the second position 68, the second passage 60 becomes substantially closed such that the flow of pressurized oil 34 from the pump 32 is generally blocked. As the pressure of the oil in the gallery 38 slowly decreases below the threshold oil pressure value due to various factors, such as leakage, the pressure inside the pressure chamber 52 is also decreased because of the chamber's communication with the gallery via third passage 64. Such a decrease in pressure inside the pressure chamber 52 permits the spring to shift the piston 46 back toward the first position 66, which allows the pressurized oil 34 to again be supplied into the gallery 38.
The described feed-back control of pressurized fluid by the valve assembly 40 may be continuous during the entire operation of the engine 12. Accordingly, because the pressure of oil in the gallery 38 is not permitted to increase past the established threshold oil pressure value, the actual amount of oil flowing through the gallery is reduced. The feed-back control provided by the valve assembly 40 serves to also reduce oil leakage in the lubrication system of the engine 12 by controlling oil flow from the second passage 60 to the first passage 56 according to the threshold oil pressure value. Additionally, such reduced amount of oil pressure and flow tends to reduce parasitic losses in the valve train 20 and further improve operating efficiency of the engine 12.
While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.
