WO2013142226A2

WO2013142226A2 - Spring-less directional solenoid valve for engine valve lift control

Info

Publication number: WO2013142226A2
Application number: PCT/US2013/031181
Authority: WO
Inventors: Joseph P. Reilly
Original assignee: Parker-Hannifin Corporation
Priority date: 2012-03-20
Filing date: 2013-03-14
Publication date: 2013-09-26
Also published as: WO2013142226A3

Abstract

A directional solenoid valve for engine valve lift control includes a poppet guide having a first port, a second port in communication with the first port, and a valve seat between the first port and the second port. The valve further includes a poppet slidably moveable in the poppet guide between a first position where the poppet is seated against the valve seat and a second position removed from the valve seat. A bias force is generated to move the poppet relative to the guide under pressure on either (i) a differential area of the poppet guide less a seat area in communication with the first port or (ii) the seat area in communication with the second port, relative to opposing pressure on an opposing side of the poppet.

Description

SPRING-LESS DIRECTIONAL SOLENOID VALVE FOR ENGINE VALVE LIFT

CONTROL

Related Applications

This application claims the benefit of U.S. Provisional Application No.

61/613,365 filed March 20, 2012, which is hereby incorporated herein by reference.

Field of the Invention

The invention described below relates to solenoid valves used in internal combustion engines to help control valve lift.

Background of the Invention

In an internal combustion engine, cams were traditionally used to control the lift of intake and exhaust valves. The cams controlled not only when the valves opened, but how far they opened. To increase engine efficiency, the amount of lift can be varied, particularly for the intake valve. Varying the lift can be accomplished in several ways, but typically decouples the valve from a direct physical contact with the cam. One way is to interpose a hydraulic pump and hydraulic cylinder between the cam and the valve stem. A solenoid valve can then be used to control the amount of hydraulic fluid, thereby varying the action of the hydraulic cylinder coupled to the valve, in particular the stroke of the hydraulic cylinder and thus the lift of the valve.

Traditional on/off solenoid cartridge valve designs use a spring to return and to bias a balanced area spool or poppet to a neutral position. The bias spring loads are designed with forces low enough to allow the solenoid armature to move the poppet to the energized state when current is applied, yet high enough to return the poppet to the neutral state when current is removed. Summary of the Invention

With advances in controllers, these solenoid cartridge valves have been operated digitally with a high frequency on/off switching signal as a way to achieve a proportionally averaging pressure or flow output from the valve. Unfortunately, the drive frequencies and the desired expected life of these valves have increased to the point that the material limitations of the traditional bias return springs have led to a substantial increase in spring failures.

The present invention provides a valve that can operate at high frequencies without a bias return spring. Elimination of the bias return spring is possible by replacing the balanced poppet with a hydraulically imbalanced arrangement. The unbalanced arrangement provides a bias return force from a first hydraulic pressure acting on the differential area of a poppet guide relative to seat areas at a first port as compared to a second hydraulic pressure acting on the seat area at a second port. The opposing pressure acting on the back side of the poppet is resolved to vent, via internal sense checks, to the lowest pressure at either the first port or the second port. This resolving feature ensures that the reactive force is acting in a directional vector to move the poppet to the neutral or open position.

More particularly, the present invention provides a directional solenoid valve for engine valve lift control that includes a poppet guide having a first port, a second port in communication with the first port, and a valve seat between the first port and the second port. The valve further includes a poppet slidably moveable in the poppet guide between a first position where the poppet is seated against the valve seat and a second position removed from the valve seat. A bias force is generated to move the poppet relative to the guide under pressure on either (i) a differential area of the poppet guide less a seat area in communication with the first port or (ii) the seat area in communication with the second port, relative to opposing pressure on an opposing side of the poppet.

The valve provided by the invention further includes one or more of the following features: (a) a valve where the first port is transverse to the second port; (b) a valve where the first port includes a passage that extends through the poppet guide, and the valve seat is adjacent the first port such that when the poppet is in the first position the poppet blocks the first port, such that the poppet is interposed between opposing passages of the first port; (c) a valve where the poppet is movable along an axis aligned with the axis of the second port; (d) a valve where the poppet guide includes a passage connected to the first port and the second port, the passage being sized to closely receive the poppet, the valve seat being formed at an end of the passage by an inwardly-facing surface dimensioned to receive a corresponding surface of the poppet to form a seal therebetween; (e) a valve having a housing to which the poppet guide is connected, a connecting rod in communication with the poppet, a magnetic coil, a magnetic stator, and a plunger movable in response to energization of the coil, the plunger in communication with the connecting rod to move the poppet against the bias force; (f) a valve where the poppet includes a passage open to the opposite side of the poppet, the passage including branches coupled to the first port and the second port, respectively, each branch including a resolver check valve, the passage thus venting pressure from the opposing side of the poppet to the lower pressure at either the first port or the second port whenever the opposing pressure exceeds the pressure at either the first port or the second port; and (g) a valve where the poppet has at an end opposite the valve seat a first pressure surface area greater than the area of the valve seat such that fluid pressure acting on opposite ends of the poppet will be unbalanced, thereby imparting to the poppet a biasing force that biases the poppet against the valve seat.

Further features of the invention will become apparent from the following detailed description when considered in conjunction with the drawings.

Brief Description of the Drawings

FIG. 1 is a cross-sectional view of a valve provided in accordance with the invention.

FIG. 2 is a cross-sectional view of an engine according to the prior art, of the kind described in U.S. Patent Application Publication No. 2010/0294220 A1 , hereby incorporated herein by reference, in which the on/off solenoid valve cartridge can be replaced by the valve of FIG. 1 .

Detailed Description

Referring now to the drawings in detail, the present invention provides a a directional solenoid valve for engine valve lift control that can operate at high frequencies without a bias return spring, and an exemplary embodiment of a directional solenoid valve 600 provided by the invention is shown in FIG. 1 .

Elimination of the bias return spring is possible by replacing the balanced poppet with a hydraulically imbalanced arrangement. The unbalanced arrangement provides a bias return force from a first hydraulic pressure acting on the differential area of a poppet guide 602 relative to an area of a valve seat (seat area) 610 at a first port 604 as compared to a second hydraulic pressure acting on the seat area 610 at a second port 606. The opposing pressure acting on the back side of a poppet 612 is resolved to vent, via internal sense checks, to the lowest pressure at either the first port 604 or the second port 606. This resolving feature ensures that the reactive force is acting in a directional vector to move the poppet 612 to the neutral or open position.

An exemplary use of such a solenoid valve is in an engine, such as the multi- cylinder engine illustrated in FIG. 2. This engine is described in U.S. Provisional Patent Application Publication No. 2010/0294220 A1 , the entire disclosure of which is hereby incorporated herein by reference. The engine is a multi-cylinder engine with a cylinder head 1 . For each cylinder, the head 1 has a cavity 2 that defines the combustion chamber. Two intake pipes 4 and 5 and two exhaust pipes 6 (one shown) connect to the cavity 2. The communication of the two intake pipes 4 and 5 with the combustion chamber 2 is controlled by two intake valves 7 (one shown), each of which includes a stem 8 slidably mounted in the body of the head 1 . Each valve 7 is returned towards its closing position by helical springs 9. The opening of the intake valves 7 is controlled by a camshaft 1 1 having a plurality of cams 14 for the valve actuation. Each cam 14 controls one intake valve 7 that cooperates with the cap 15 of a tappet 16 slidably mounted along an axis 17. The tappet 16 is slidably mounted within a bushing 18, which in turn is supported by a body 19 of a preassembled group 20. The group 20 embeds all the electric and hydraulic devices associated to the intake valve actuation. Tappet 16 can transmit a thrust to the stem 8 of the valve 7, in such a way as to cause the valve 7 to open against the action of the springs 9, by fluid under pressure (typically oil coming from the engine lubricating circuit). The oil flows from a chamber C to the chamber of a hydraulic actuator associated with the valve 7, where it causes the displacement of a piston 21 .

The pressure chamber C can be put into communication with the exhaust channel 23 via a solenoid valve 24. The solenoid valve 24 is controlled by electronic control means, schematically shown at 25, on the basis of signals S that indicate engine operating parameters, such as gas pedal position, engine rotating speed, room temperature, engine block temperature, engine cooling liquid temperature, pressure in the engine intake manifold, viscosity and/or temperature of the oil in the intake valve hydraulic actuating system.

When the solenoid valve 24 switches from the closed condition to the open condition, chamber C starts communicating with the channel 23, so that the fluid under pressure in chamber C flows into the channel 23 and an uncoupling is obtained of the tappet 16 from the respective intake valve 7, which therefore rapidly returns to its closing position, under the action of the return valve 9. By controlling the communication between chamber C and the outlet channel 23, it is therefore possible to vary at will the time in the opened condition and the lift of each intake valve 7.

The exhaust valves 70 associated with respective cylinders are

conventionally controlled by a camshaft 28 via respective tappets 29, even though as a principle it is also possible, both in the case of the said prior art document and in the present invention, to apply the variable valve actuating system to the exhaust valve control as well. The variable volume chamber defined within the bushing 22 of the piston 21 (the piston being shown in its end-of-stroke position) communicates with the pressurized fluid chamber C through an opening 30 obtained in an end wall of the bushing 22. This opening 30 is engaged by an end snug 31 .

During normal engine operation, when the solenoid valve 24 stops the communication of the pressurized fluid chamber C with the exhaust channel 23, the oil in the chamber transmits the movement of the tappet 16, imposed by the cam 14, to the piston 21 controlling the opening of the valve 7. At an early stage of the opening movement of the valve, the fluid coming from chamber C reaches the variable volume chamber of the piston 21 , passing through an axial hole obtained in the snug 30. The check valve 32 and further passages that make the inner cavity of the piston 21 communicate with the variable volume chamber. After a first displacement of the piston 21 , the snug 31 is extracted from the opening 30, so that the fluid coming from chamber C can directly flow into the variable volume chamber through the opening 30, which is now free. In the reverse movement of valve closing, as previously mentioned, during the final stage the snug 31 enters the opening 30, thus causing the hydraulic braking of the valve, in such a way as to avoid an impact of the valve body against its seat when pressure chamber C is devoid of the fluid. Further description of such a system can be found in the aforementioned publication.

Returning to the exemplary directional solenoid valve shown in FIG. 1 , the valve 600 includes a poppet guide 602 having a first port 604, a second port 606 in communication with the first port 604, and a valve seat 610 between the first port 604 and the second port 606. The valve 600 further includes a poppet 612 slidably moveable in the poppet guide 602 between a first position where the poppet is seated against the valve seat 610 and a second position removed from the valve seat. A bias force is generated to move the poppet 612 relative to the guide 602 under pressure from either (i) a differential area of the poppet guide 602 (poppet guide area AG) less a seat area (AS) in communication with the first port 604, or (ii) the seat area (AS) in communication with the second port 606, relative to opposing pressure on an opposing side 614 of the poppet 612.

The poppet guide 602 includes a passage 616 connected to the first port 604 and the second port 606. The passage 616 is sized to closely receive the poppet 612. The valve seat 610 is formed at an end of the passage 616 by an inwardly- facing surface dimensioned to receive a corresponding surface of the poppet 612 to form a seal therebetween. The poppet 612 is movable along an axis 620 aligned with an axis of the second port 606.

In the illustrated embodiment, the first port 604 is transverse to the second port 606. The valve seat 610 is adjacent the first port 602 such that when the poppet 600 is in the first position the poppet 612 blocks the first port 604. The first port 604 includes a passage that extends through the poppet guide 602. As a result, when the poppet 612 extends into the path of the first port 604, the poppet 612 is interposed between opposing passages of the first port 602, and the first port 604 provides access, and thus the ability to apply pressure, to the poppet 612 from at least two sides. Outside the valve 600, the separate passages that make up the first port 604 typically will be connected.

The poppet 612 has at an end 614 opposite the valve seat 610 a first pressure surface area greater than the area (AS) of the poppet 612 adjacent the valve seat 610 such that fluid pressure acting on opposite ends of the poppet 612 will be unbalanced, thereby imparting to the poppet 612 a biasing force that biases the poppet 612 against the valve seat 610. The valve 600 further includes a housing 622 to which the poppet guide 602 is connected, a connecting rod 624 in communication with the poppet 612, a magnetic coil 626, a magnetic stator 630, and a plunger 632 movable in response to energization of the coil 626. The plunger 632 is in communication with the connecting rod 624 to move the poppet 612 against the bias force. The poppet 612 also includes a passage 634 open to the opposite side 614 of the poppet 612. The passage 634 has branches coupled to the first port 604 and the second port 606, respectively, each branch including a resolver check valve 636 and 638. The passage 634 thus vents pressure from the opposing side 614 of the poppet 612 to the lower pressure at either the first port 604 or the second port 606 whenever the opposing pressure exceeds the pressure at either the first port 604 or the second port 606.

FIG. 3 illustrates a control system schematic.

The present invention provides a directional solenoid valve capable of meeting the digital switching demands, even as life expectancies of such valves have increased to 500,000,000 cycles in engines using digital valve lift control. Eliminating the spring, along with the stresses endured by the spring material, enables the solenoid valve described herein to meet such endurance and reliability requirements. Removal of the spring improves the predicted life cycle by

eliminating the limits of material properties, critical frequencies, and life

expectancies associated with the spring.

Further advantages can be realized in the fact that the bias load is no longer a function of spring height, but rather is a function of the reactive force from the pressure applied to the differential area created by the imbalance. In short, the bias load will vary with the pressure applied, and is not fixed to the mechanical envelope that the traditional spring operates within.

Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements

(components, assemblies, devices, compositions, etc.), the terms (including a reference to a "means") used to describe such elements are intended to

correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.

Claims

Claims What is claimed is:

1 . A directional solenoid valve for engine valve lift control, the solenoid valve comprising:

a poppet guide having a first port, a second port in communication with the first port, and a valve seat between the first port and the second port; and

a poppet slidably moveable in the poppet guide between a first position where the poppet is seated against the valve seat and a second position removed from the valve seat, where a bias force is generated to move the poppet relative to the guide under pressure on either (i) a differential area of the poppet guide less a seat area in communication with the first port or (ii) the seat area in communication with the second port, relative to opposing pressure on an opposing side of the poppet.

2. A valve as set forth in claim 1 or any other claim, where the first port is transverse to the second port.

3. A valve as set forth in claim 1 or any other claim, where the first port includes a passage that extends through the poppet guide, and the valve seat is adjacent the first port such that when the poppet is in the first position the poppet blocks the first port, [the poppet is interposed between opposing passages of the first port]

4. A valve as set forth in claim 1 or any other claim, where the poppet is movable along an axis aligned with the axis of the second port.

5. A valve as set forth in claim 1 or any other claim, where the poppet guide includes a passage connected to the first port and the second port, the passage being sized to closely receive the poppet, the valve seat being formed at an end of the passage by an inwardly-facing surface dimensioned to receive a corresponding surface of the poppet to form a seal therebetween.

6. A valve as set forth in claim 1 or any other claim, comprising a housing to which the poppet guide is connected, a connecting rod in communication with the poppet, a magnetic coil, a magnetic stator, and a plunger movable in response to energization of the coil, the plunger in communication with the connecting rod to move the poppet against the bias force.

7. A valve as set forth in claim 1 or any other claim, where the poppet includes a passage open to the opposite side of the poppet, the passage including branches coupled to the first port and the second port, respectively, each branch including a resolver check valve, the passage thus venting pressure from the opposing side of the poppet to the lower pressure at either the first port or the second port whenever the opposing pressure exceeds the pressure at either the first port or the second port.

8. A valve as set forth in claim 1 or any other claim, where the poppet has at an end opposite the valve seat a first pressure surface area greater than the area of the valve seat such that fluid pressure acting on opposite ends of the poppet will be unbalanced, thereby imparting to the poppet a biasing force that biases the poppet against the valve seat.