The present invention relates to internal combustion engines; more particularly, to valves for controlling the flow of oil to oil-activated engine components such as variable valve actuators and camshaft phasers; and most particularly, to a compound valve for controlling oil flow alternatively at a high pressure for element activation and at a low pressure for element deactivation.
It is known that for a portion of the duty cycle of a typical multiple-cylinder internal combustion engine, the load can be met by a functionally smaller engine having fewer firing cylinders, and that at low-demand times fuel efficiency can be improved if one or more cylinders of a larger engine can be withdrawn from firing service. It is known in the art to accomplish this by de-activating a portion of the valve train associated with pre-selected cylinders in any of various ways. For example, a special cam finger follower having a latching pin or slide which may be actuated and/or deactuated hydraulically. The cam finger follower is so configured that it causes low or no lift of the valve when the pin is disengaged and high lift of the valve when the pin is engaged. Various methods and apparatus for actuating this type of latching pin or slide are known. For example, U.S. Patent Application Publication No. U.S. 2003/0200947 A1 discloses a hydraulic apparatus and return spring for latching and delatching a latching pin of a deactivating roller finger follower. The latching pin is disposed in, and extends from, a bore in an outer finger arm which is supported by a hydraulic lash adjuster. When moved inwards of the outer finger arm, the pin engages a central slider member which follows the surface of a camshaft lobe. When valve deactivation is desired, engine oil pressure supplied to the apparatus is increased to a level sufficient to overcome the force of the return spring and move the latching pin out of engagement with the slider member. The slider member continues to follow the surface of the camshaft, but the cam motion is not translated to the outer finger arm, and the valve is not actuated thereby.
For another example, a special hydraulic valve lifter having radially-operative latching pins also may be actuated or deactuated hydraulically. When the lifter is deactuated by high-pressure oil overcoming a latching spring, a pushrod seat is disengaged to deactivate the associated engine valve, while the cam-follower portion continues to follow the cam lobe in lost motion.
In providing such actuation mechanisms, it can be advantageous to provide ordinary engine oil as the pressurized actuating medium, supplied conventionally from the main engine oil pump via a standard engine oil gallery with minimal special oil porting. Further, it is advantageous to be able to throttle the flow of oil between high-flow/high-pressure and low flow/low-pressure without ever completely shutting off the flow of oil, as is the case in prior art on/off solenoid-actuated spool valves.
It is a principal object of the present invention to controllably vary the flow of pressurized oil between a high-flow/high-pressure condition and a low flow/low-pressure condition.
It is a further object of the invention to provide such control electromechanically via a simple solenoid valve.
Briefly described, a compound valve assembly for controlling high and low oil flow and pressure in accordance with the invention includes a first valve and a second valve. The first valve serves as a pressure relief valve which, in the example shown, includes a spring-biased cup-shaped plunger disposed in a side gallery opening off a primary oil supply gallery leading to or from a device to be oil-actuated. The plunger is seated in a first valve seat, and the relief spring is sized such that the plunger is displaced conventionally from the first valve seat at a predetermined upper limit of oil pressure to allow some oil to flow past the plunger and to be returned to the oil sump. The side gallery is closable at its opposite end by a secondary valve seat and a solenoid-actuated/spring-returned valve head. A small passage through the plunger end leads to the second valve seat, whereby a chamber within the plunger is filled with oil. When the solenoid is deactivated, oil also flows through the passage, through the second valve, and is returned to the sump. Thus, the flow and pressure of oil-flowing through the primary oil gallery to the control device are both low because much of the supplied oil bypasses the control device. When high oil flow and pressure are desired at the control device, the solenoid is energized, closing the second valve and capturing oil within the plunger. Because of communication through the plunger passage, the captive oil assumes the same pressure as the supply pressure in the primary gallery, and the relief valve function is disabled. Thus the flow and pressure of oil flowing through the primary gallery to the control device are both high. To deactuate the valve assembly, the solenoid is de-energized, reopening the second valve and again permitting oil pressure relief around and through the plunger.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Referring to
First valve body 12 includes a second well 28 terminating in communication with first chamber 25 and defining an annular first valve seat 30 therebetween. A cup-shaped relief valve plunger 32 is disposed in second well 28 and is urged against first valve seat 30 by a compression spring 34 disposed within a second chamber 36 within relief valve plunger 32. A reduced-diameter portion 38 of first valve body 12 defines an annular space 40 between portion 38 and first well 14 of engine 16. Parasitic oil flow 42 being relieved by oil pressure displacement of relief valve plunger 32 from first valve seat 30 flows through radial port 44 into annular space 40.
A second valve 45 includes a second valve body 46 having a first diameter portion 48 that is close-fitted into second well 28 in first valve body 12 and a second diameter portion 50 that is sealed as by an O-ring 52 against flange 54 of first body 12. Second valve body 46 includes a third well 56 concentric with first and second wells 14,28, terminating in a second valve seat 58 surrounding a passage 60 between second chamber 36 and third chamber 62 in second valve body 46. Second valve body 46 further defines a spring seat 35 (
A solenoid actuator 70 having windings 71 is concentrically mounted onto second valve body 46 and includes a slidable armature 72 supportive of a secondary valve pintle 74 and valve head 76 for variably mating with second valve seat 58. A return spring 78 holds the secondary pintle valve 74 in the open position when the solenoid is de-energized.
A passage 67 is provided through the end 69 of plunger 32, permitting oil from first chamber 25 to enter second chamber 36 within relief valve plunger 32 and to flow through the secondary valve when open and return to the engine sump via port 64.
In operation in low-flow/low-pressure mode, as shown in
It is an important aspect of the present invention that oil flow through control gallery 22 is never shut off, as it is in prior art spool valves, and always flows at some predetermined minimum flow rate and pressure.
Referring to
Thus the primary and secondary objects of the invention are realized: to controllably vary the flow of pressurized oil between a high-flow/high-pressure condition and a low flow/low-pressure condition, and to provide such control electromechanically via a simple solenoid valve.
While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims.