GB2180039A

GB2180039A - Solenoid operated fluid control valve

Info

Publication number: GB2180039A
Application number: GB08617852A
Authority: GB
Inventors: Takeo Kushida
Original assignee: Diesel Kiki Co Ltd
Current assignee: Bosch Corp
Priority date: 1985-07-31
Filing date: 1986-07-22
Publication date: 1987-03-18
Also published as: KR920007707B1; JPS6231786A; GB8617852D0; KR870001390A; DE3625918A1

Abstract

A quick response solenoid valve includes a valve element 8 connected to an armature 4, and a pair of first and second springs 17,22 disposed on opposite sides of the armature 4 in such a manner as to cancel out the preloading on the respective springs. With the springs thus preloaded, the use of each spring in an unstable non-linear zone of its stress-strain diagram can be avoided. Preferably the coil assembly includes concentric annular coils 7a-7d such that the current in adjacent coils flows in opposite directions. The preloading on the springs may be adjustable by means of a bolt 28 and/or shim(s) 21. <IMAGE>

Description

SPECIFICATION Solenoid operated fluid control valve The present invention relates to a solenoid operated fluid control valve suitable for use with a fuel injection pumpfordiesel engines to control afuel to be supplied to or overflowing from the fuel injection pump.

Typical solenoid operated fluid control valves of the type described are disclosed in Japanese Patent Laid-open Publication Nos. 59-166778 and 60-56137.

The disclosed valves comprise an electromagnetic actuator or solenoid composed of a stator and a reciprocably movable armature, a valve element connected with the armature and adapted to be displaced in one direction when the solenoid is energized, and a spring for urging the valve element in the opposite direction to return to its original position when the solenoid is de-energized.

The spring ofthe prior valve is disposed on only one side ofthe valve element under preloaded condition so asto avoid an unstable non-linearzone of its spring property curve or stress-strain diagram which appears when the spring is elastically deformed to a predetermined extent from its free state.

With this construction, the armature and hence the valve element is kept immovable until the electromagnetic forces acting thereon exceed the preload on the spring even though the exciting current is supplied to an exciting coil ofthe solenoid. Thus a quick response of the valve element cannot be expected. Furthermore, excess electromagnetic energy is necessaryto actuatethevalveelement,thusincreas- ing loads on the solenoid and lowering the working efficiency ofthe solenoid.

It is accordingly an object of the present invention to provide a solenoid operated fluid control valve with spring means which may be active in a stable linear zone of its spring property curve, while enabling the valve to operate in quick response to the energization and de-energization of a solenoid without causing a loss of energy and a reduction of working efficiency.

The invention provides a solenoid operated fluid control valve comprising: (a) an electromagnetic actuator including a statorwith an exciting coil assemblythereon and an armature disposed opposite to said stator and reciprocably movable in responseto energization and de-energization of said exciting coil; (b) a valve element secured to said armature of said electromagnetic actuator; (c) a valve housing having a flow passage defined therein and a valve seat against which said valve element is releasably seated to open and close said flow passage; (d) a firstspringforurging said armature in one direction; and (e) a second spring for urging said armature in the opposite direction.

With this construction, the armature and hence the valve element may gives a preload on each ofthefirst and second springs so that each spring acts only in a stable linear zone of its spring poiperty curve or stress-strain diagram. Furthermore, the first and second springs are preloaded in opposite directions so as to take up or cancel out the preload exerted thereon with the result that the armature and the valve element connected thereto are held in substan tiallynon-loaded conditionswhentheelectro- magnetic actuator is de-energized.

Many other advantages, features and other objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheet of drawing in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example.

The Figure is a vertical cross-sectional view of a solenoid operated fluid control valve embodying the present invention.

As shown in the drawing figure, a solenoid oper atedfluidcontrol valve embodyingthe present in- vention is suitable for use with a fuel injection device (not shown) to control a fuel to be supplied to or overflowing from the fuel injection device. The control valve includes a valve housing 1 adapted to bethrea- ded to the fuel injection device. The housing 1 has a generally stepped cup-likeshape and includes an in ternally threaded annular upper end portion to which an externallythreaded peripheral portion of a stator2 is threaded, the stator 2 being made of a magnetic material. The valve housing 1 and the stator 2 thus connected jointly define therebetween an annular armature-working chamber3 in which an armature4 of magnetic material is movably received.

The stator2 and the armature 4each haveadisc- like shape and they are disposed one above the other with a lower end face ofthe stator 2 confronting to an upper end face ofthe armature 4. The stator 2 and the armature 4thus arranged jointly constitute an electromagnetic actuator or solenoid 5. The stator 1 of the solenoid 5 includes a plurality (four in the illustrated embodiment) of annular grooves 6 defined concentrically in the lower end face thereof for receiving respectively therein a plurality of annular exciting coils 7a-7d. The exciting coils 7a-7d jointly constitute an exciting coil assembly for exciting the solenoid 5 to pull the armature 4toward the magnetized stator 1.The exciting coil assembly is energized such that one ofthe exciting coils 7a-7d, for example, the exciting coil 7b receives an exciting currentflowing therethrough in a direction which is opposite to the direction of flow of an exciting currentflowing through an adjacent exciting coil 7a, 7c. When energized, the exciting coil assembly produces, in the vicinity of the respective exciting coils 7a-7d, a plurality of lines of magnetic flux flowing between the stator 2 and the armature 4 in different directions. With this arrangement, leakage of magnetic flux is substantially negligible and a highly efficient magnetic circuit is produced between the stator 2 and the armature 4.

Avalve element8 is in the form of an elongate rod and includes an externally threaded upper end portion of a reduced diameter extending through a central hole 9 in the armature 4. A lower spring seat or retainer 27 is threaded overthethreaded upper end portion ofthe valve element 8 to secure the latterto the armature 4 with a shoulder ofthe valve element8 abutting against a lower end face of the armature 4.

The valve element 8 extends downwardly from the armature 4 and is slidably received in a central axial bore 10 in the valve housing 1. The valve element8 includes, at its lower end, a valve head or poppet 11 which is brought into and out of engagement with a valve seat 12 defined in a lower end face ofthe hous- ing 1 and extending around a lower end ofthe axial bore 10.The valve housing 1 includes a pair of fuel inlets 13a, 13b, a pair offuel passageways 14a, 14b extending inwardly from the respective fuel inlets 13a, 13b, and a fuel sump 15 defined around the valve element8 and communicating with the axial bore 10 and with thefuel passageways 14a, 14b.Thus, one of the inlets 13a, 13b, a corresponding one of the passageways 14a, 14b,thefuel sump 15, andtheaxial bore 10 jointlyform a flow passage which is closed and opened by the valve head 11.

The valve housing 1 also includes a plurality of internal overflow grooves 1 6a - 1 6d for returning therethrough the fuel, which has leaked into the pumpworking chamber 3, to a low-pressure side of the fuel injection device.

Afirst spring 17 is provided for urging the armature 4 and the valve element 8 connected thereto toward the stator 2. In the illustrated embodiment,the first spring 17 is composed of a compression coil spring and disposed in the armature-working chamber3 below the armature 4. The first spring 17 is retained at its upper end by an upper spring seat or retainer 18 and at its lower end by a lower spring seat or retainer 19. The upper spring retainer 18 is fitted over a cylindrical central lower end portion of the armature 4.

The lower spring retainer 19 is fitted over a cylindri cal central upper end portion of a base 20 which is fitted around the valve element 8 and threaded to the housing 1 with a spacerwasher or shim 21 disposed therebetween. By changing the thickness of the shim 21 for varying distance between the upper and lower spring retainers 18, 19, the magnitude of preloading on the first spring 17 can be adjusted.

A second spring 22 is provided for urging the armature 4 and the valve element8 connected thereto in a direction away from the stator 2. The second spring 22 is in the form of a compression coil spring disposed in a spring chamber 25 which is defined by and between a bored central portion ofthe stator 2 and a cup-shaped cover 24 secured buy a screw 23two an upperend of the stator2. The second spring 22is retained at its upper end by an upper spring seat or retainer 26 and at its lower end by the lower spring retainer 27 which is threaded on the upper end portion ofthe valve element 8, as described above. The upper spring retainer 26 is coupled with an adjust ment bolt28threaded axiallythrough the central portion ofthe cup-shaped cover 24.The adjustment boit 28 is secured to the cover 24 by a lock nut 29. With this construction, with the lock nut 29 loosened, the adjustment bolt 28 is turned in either direction to varythe distance between the upper and lower spring retainers 26,27, thereby adjusting the magnitude of preloading on the second spring 22.

The solenoid operated fluid control valve thus constructed operates as follows. An electric current is supplied to the exciting coils 7a - 7d of the solenoid 5 to magnetize the stator 2 whereupon the armature 4 is pulled upwardly toward the magnetized stator 2.

The upward movement of the armature 4 causes the valve head 11 of the valve element 8 to seat against the valve seat 12, thereby closing the flow passage in the housing to block the fuel, as shown in the drawing figure. When cu rrent supply to the exciting coils 7a - 7d is interrupted to de-magnetize the stator 2, the armature 4 and the valve element 8 are forced downwardly away from the stator 2 by a combined force of the first and second springs 17,22. The downward movement of the valve element 8 causes the valve head 11 to move away from the valve seat 12, thereby opening the flow passage in the housing 1.The second spring 22 has a spring force greater than the force of the first spring 17 so thatthe downward movement of the valve element 8 continues until the spring forces of the first and second springs 17,22 balance two each other. In this instance, the armature4 and hence the valve element 8 is kept in non-loaded condition. Partly because the first and second springs 17,22 are preloaded in such a manner as to avoid unstable non-linearzones of their spring property curves orstress-strain diagrams, and partly becausethe armature 4 and the valve element 8 are kept in non-loaded conditions when the solenoid 5 is deenergized, the armature 4 and the valve element 8 are actuated to close the flow passage, in immediate responseto energization of the solenoid 5.

Although the first and second springs 17,22 in the illustrated embodiment comprise compression coil springs, they may be replaced by springs of other types, such as tension springs.

Obviously, many modifications and variations of the present invention are possible in the light ofthe above teachings. It is therefore to be understood that within the scope ofthe appended claims, the invention may be practised otherwisethan as specifically described.

Claims

1. A solenoid operated fluid control valve comprising; (a) an electromagnetic actuator including a stator with an exciting coil assembly thereon and an armature disposed opposite to said stator and reciprocably movable in response to energization and deenergization ofsaid exciting coil; (b) a valve element secured to said armature of said electromagnetic actuator; (c) a valve housing having a flow passage defined therein and a valve seat againstwhich said valve element is releasably seated to open and close said flow passage; (d) a first spring for urging said armature in one direction; and (e) a second spring for urging said armature in the opposite direction;

2.A solenoid operated fluid control valve accord ing toclaim 1,said exciting coil assembly including a plurality of annular exciting coils disposed in concentric relation to one another, each adjacent pair of said exiting coils being adapted to be energized by sending currentthrough them in opposite directions.

3. A solenoid operated fluid control valve accord ingto claim 1 or 2 including a shim for adjusting the magnitude of preloading on either one of said first and second springs.

4. A solenoid operated fluid control valve according to any preceding claim, including an adjustment bolt for adjusting the magnitude of preloading on either one of said first and second springs.

5. A solenoid operated fluid control valve according to any preceding claim, said first and second springs comprising compression coil springs.

6. A solenoid operated fluid control valve su b- stantially as described with reference to, and as shown in, the accompanying drawing.