US3036808A - Stepped-opening solenoid valve - Google Patents

Description

L. C. FOX

STEPPED-OPENING SOLENOID VALVE May 29, 1962 Filed June 29, 1959 Cl MD M Y 3 E: 3;: r; m 4

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I NVE NTO R LEONARD C. FO BYg /z I HIS AGFNT United States 3,036,808 STEPPED-OPENING SOLENOID VALVE Leonard C. Fox, Moiine Acres, Ma, assignor, by mesne assignments, to Emerson-White-Rodgers Company, a corporation of Missouri Filed June 29, 1959, Ser. No. 823,608 7 Claims. (Cl. 25154) This invention relates to normally closed, solenoid operated valves for controlling the flow of fuel to gas-fired furnaces and more particularly to the provision of means for effecting the stepped-opening operation of the. valve, wherein, upon energization of the solenoid, the valve opens partially a predetermined amount so as to supply a limited, initial amount of fuel to establish a limited, initial combustion in the furnace combustion chamber, then dwells in this partially open position for an interval to permit the development of natural draft through the combustion chamber and then moves to its full open position. This manner of valve operation precludes objectionable flame roll-out in compact furnaces of relatively large heat output.

An object of the invention is to provide a normally closed solenoid operated gas valve having means operative to arrest the valve at a predetermined partially open position as it is being opened by the solenoid, to detain it in this partially open position for a predetermined interval and to then permit it to continue to a full open position;

A further object is to include means in a steppedopening solenoid operated gas valve of the above character for selectively varying the point at which the valve, when being opened, is momentarily detained;

More specifically, it is an object to utilize the characteristic, slowly yielding resistance to separation of a pair of very closely spaced parallel plates immersed in a viscous liquid to detain the valve in some partially open position for a predetermined interval.

Further objects and advantages will appear from the following description and accompanying drawing in which;

FIG. 1 is a longitudinal cross-sectional view of a solenoid valve constructed in accordance with the present invention;

FIG. 2 is a fragmentary portion of the view in FIG. 1, showing the device in a different operative position;

FIG. 3 is a transverse cross-sectional view of the solenoid valve taken along line 33 of FIG. 1; and

FIG. 4 is an enlarged fragmentary crosssectional view of the parallel plates showing means for uniformly spacing the plates in close proximity.

Referring to the drawing in more detail, a valve body is indicated at having an inlet passageway 12, an outlet passageway 14, and a partition 16 separating the inlet and outlet passages. The partition 16 has a port 18 therein fitted with a resilient valve seat 20. Mounted on the valve body and attached thereto by suitable means is an upper casing 24 which houses the solenoid valve actuator. The casing is filled with a viscous liquid 22 and is provided with a sealing top cover 26 of magnetic material from which the solenoid actuator is suspended in the liquid.

The solenoid actuator comprises a winding 28, a com tral plunger sleeve 30 of non-magnetic material, and a plunger 32 of magnetic material slidably arranged in the plunger guide sleeve 30. The solenoid Winding 28 is encased in a supporting frame of magnetic material consisting of members 34 and 36 each having a formed leg indicated at 38 and 40 respectively, which legs are attached to the underside of the cover 26 in any suitable manner such as welding. A centrally perforated plunger stop member 42 of magnetic material fixed in the right end of sleeve 36 limits the travel of plunger 32 toward the right when the winding 28 is energized and serves to complete with frame members 34 and 36 and the cover 26, a low reluctance path for the magnetic field generated by the winding 28.

A push rod 44, press fitted into a longitudinal bore in plunger 32, projects from the right end of the plunger and extends through stop member 42 and engages the upper free end of an upstanding arm 46. The arm 46 is attached at its lower end by a screw 48 to the interiorly extending portion of a rocker shaft 50, which rocker shaft is journalled in opposite walls 52 and 54- of the casing 24 and extends exteriorly of the casing through the casing wall 54, as shown in FIG. 3. In order to provide a seal against leakage of liquid from casing 24 through the rocker shaft journal in wall 54-, a pair of rubber 0 rings 55 are fitted in suitable annular grooves in the rocker shaft 50. Attached at one end to the exteriorly extending portion of shaft Si} by a screw 56 is a second horizontally arranged arrn57 which carries at its free end a valve 58 arranged to cooperate with the valve seat 20 to control the flow of fuel through the valve body 10. A compression spring 60 acting through the arms 46 and 57 biases the valve 58 in a closed position on valve seat 20 and returns plunger 32 to the left when the winding 28 is de-energized.

The mm 46 carries a plate 62 which is pivotally mounted at its lower end to the arm 46. The pivotal connec tion of the lower end of plate 62 to arm 46 is accomplished by providing a pair of formed tangs 64 on the lower end of plate 62. which are entered into the perforations 63 as indicated. The arm 46 and plate 62 have enlarged, circular, upper portions which provide extensive, fiat, adjacent, matching surfaces. The plate 62 is provided with a plurality of small circular coined bosses 66 of uniform height to provide a minimum spacing between the meeting flat surfaces of arm 46 and plate 62. A formed leaf spring 68 attached at one end at 70 to arm 46 presses at its free end against plate 62 to urge it toward the arm 46. The plate 62 is provided with a perforation 72 at the center of its upper circular portion to permit the plunger push rod 44- to pass freely therethrough to engage arm 46. The arm 46 is provided with a clearance perforation 74 for the free passage therethrough of a threadedly adjustable stop screw 76 adapted to be engaged by the plate 62 when the arm 46 and plate 62 are rotated together with shaft 50 in a clockwise direction. The offset of the hinge tangs 64 on the plate 62 is made somewhat greater than the thickness of the arm 46 through which they pass so that the entire plate 62 may be moved perpendicular a slight amount with respect to the arm.

Operation The device is shown in a de-energized position in FIG. 1 with valve 58 in a closed position on seat 20, the plunger 32 in its returned position, and the plate 62 biased in close proximity with the upper part of arm 46 as limited by the small bosses 6. Under these conditions when solenoid winding 28 is energized the plunger 32 moves toward the right and through the push rod 44 the arm 46 with hinged plate 62 and arm 57 with connected valve 28 are rotated together with shaft 50* in a clockwise direction. When the hinged plate 62 engages the end of adjustable stop screw '76, movement of arm. 46 is arrested by the resistance to separation of the closely spaced surfaces of plate 62 and arm 46 and the valve 58 is therefore detained.

This resistance to separation of plate 62 and arm 46 is due to molecular friction or the resistance to flow of the surrounding viscous liquid into the space between the closely spaced surfaces of these members. It is to be understood that while the movement of the solenoid plunger and valve is not stopped completely when the plate 62. engages stop screw 76, their movement is, nevertheless, retarded for some definite interval to a very low velocity wherein motion is imperceptible and entirely negligible in its effect to increase fuel flow, and this retardation is therefore referred to hereinafter as an arrest or detention of the valve as it is being opened. The interval of detention of the valve will vary with the force applied by the solenoid plunger, the area and shape of the closely spaced surfaces, the viscosity of the liquid in which they are immersed, and the spacing between the surfaces.

By way of example; an average valve detention of seven (7) seconds was achieved in an experimental construction in which the meeting flat surfaces of hinged plate 62 and arm 46 were rectangular in shape, .562. x .437 inch, with a central perforation of .110 inch diameter, result ing in a net area of .23 66- square inch, the spacing of the surfaces being .0005 inch, the liquid in which they were immersed being a silicone oil of 10,000 centistokes viscosity and the net separating force applied by the solenoid plunger at the center of the flat surface of arm 46 being 20 grams. The reaction force applied to plate 62 by stop screw 76 was applied at a point outside of the surface area. By spacing the surfaces slightly as in the order of .0005 inch and using a more viscous liquid, rather than using a less viscous liquid and permitting the surfaces to come into direct contact, greater uniformity of the de tention interval was achieved. Moreover, by providing this fixed slight spacing of the surfaces, the time required for the surfaces to return to their minimum spacing at a given bias force is greatly reduced and flatness of the surfaces required to attain uniform detention time is rendered considerably less critical than when the surfaces are permitted to contact over their whole area, thereby rendering the device adaptable to low-cost manufacture.

At the termination of the interval of detention the arm 46 characteristically breaks away abruptly from the plate 62' and continues its counterclockwise rotation under the force of the solenoid plunger until the plunger engages its limiting stop 42. At this point the valve 58 is fully open, as indicated in FIG. 2. Upon dc-energization of the winding 28, the return spring 60 acting on arm 46 returns the valve 58 to its seat and the plunger to its de-energized position. As the arm 46 is being returned counterclockwise from its position in FIG. 2 to the position shown in FIG. 1 by the spring 60, the leaf spring 68 acts to return plate 62 to its closely spaced relationship with arm 46. As the surfaces on plate 6 2. and arm 46 approach their minimum spacing as provided by the bosses 66, their relative movement toward each other is slowed down considerably due to the viscosity of the liquid in which they are immersed and the time required for the plates to arrive at their minimum spacing will vary with the strength of leaf spring 68 for a given viscosity liquid.

It is to be understood that plate 62 and arm 46 may be independently slidably mounted for relative movement axially of the plunger if desired so that the entire relative and unidirectional movement of these members is perpendicular to their fiat surfaces. Also, the adjustable stop means may be so arranged that its reacting force will be applied to the center of the flat surface of the engaging member and in line with the axis of the plunger. In such arrangement there would be no peeling action during plate separation as occurs in the arrangement shown in the drawing, and less area of the meeting surfaces or a less viscous liquid could be employed to attain the same detention interval, but it is not found that any greater uniformity of detention time could be attained with such arrangement.

The foregoing description is intended to be illustrative and not limiting, the scope of the invention being set forth in the appended claims.

I claim:

1. In a solenoid valve assembly, a normally closed valve, a solenoid actuator operatively connected to said valve and which when energized opens said valve, means forming a chamber, a viscous liquid in said chamber, a first movably mounted member in said chamber having a flat surface immersed in said liquid and being mounted for movement in a plane to move its fiat surface transversely in said liquid, means including an element extending through a wall of said chamber for connecting said first member to said valve for movement therewith, a second member in said chamber carried by said first member and having a flat surface immersed in said liquid and arranged in face to face relationship with the flat surface of said first member, and said second member being movably mounted on said first member for movement of its fiat surface toward and away from the flat surface of said first member, and being arranged on that side of said first member which becomes the trailing side thereof when said first member is moved with said valve in a valve opening direction by said actuator, resilient means acting on said second member to bias its flat surface against that of said first member, whereby said first and second members normally move in unison with said valve, and stop means arranged to be engaged by said second member as it is being moved with said first member in a valve opening direction, thereby to momentarily detain the opening movement of said valve until said contiguous immersed surfaces separate under the force of said solenoid actuator.

2. In a solenoid valve assembly, a normally closed valve, means forming a chamber, a liquid in said chamber, a solenoid actuator in said chamber having a reciprocating plunger immersed in said liquid, means including a member extending through a wall of said chamber operatively connecting said valve with said plunger whereby said valve is moved to a fully open position as said plunger is moved in one direction upon energization of said actuator, resilient means operative to move said plunger in an opposite direction and said connected valve to a closed position when said actuator is d e-energized, a pair of movable members in said chamber, each having a flat surface immersed in said liquid and arranged face to face with that of the other, said members being mounted for relative movement in a plane transverse to their flat surfaces, one of said members being operatively connected to said plunger and being arranged to be moved by said plunger in a direction to tend to separate its flat surface from that surface of the other member as said plunger moves in a valve opening direction, resilient means biasing the surface of said other member against that of said one member, whereby said members normally move in unison with their flat surfaces together in a valve opening direction, stop means arranged to be engaged by said other member as said members are moved by said plunger in a valve opening direction, thereby to arrest valve opening movement until said members are separated, and said meeting fiat surfaces being of such area and the liquid in which they are immersed being of such viscosity as to require a predetermined interval. to effect the separation of said flat surfaces under the force of said actuator.

3. In a solenoid valve assembly, a valve, means biasing said valve in a closed position, a solenoid actuator operatively connected to said valve and which "when energized moves said valve to an open position, means forming a chamber, a viscous liquid in said chamber, a pair of flat plate members in said chamber immersed in said liquid, said plate members being arranged face to face and each being mounted for movement through said liquid perpendicular to its flat side, means including a member extending through a Wall of said chamber connecting one of said plate members with said valve in a manner to be moved in a direction away from the other of said plate members as said valve is moved openward by said actuator, means biasing said other plate member against said one plate member face to face, whereby said plate members normally move together in said direction as said valve is moved openward, and stop means arranged to be engaged by said other plate member as it moves in said direction with said one plate member and said valve, thereby to arrest the opening movement of said valve until said plate members are separated, and the areas of the normally contiguous surfaces of said plate members and the viscosity of the liquid in which they are immersed being such that a predetermined interval is required under the force of said solenoid actuator to effect separation of said plate members.

4. In a solenoid valve assembly, a normally closed valve, means forming a chamber, a viscous liquid in said chamber, a solenoid actuator including a reciprocating plunger immersed in said liquid, a pair of movably mounted members in said chamber each having a flat surface immersed in said liquid and arranged face to face with that of the other member, and said members being mounted for relative movement in a plane transverse to their flat surfaces, means connecting that member of the pair with said valve which, when said valve moves in an opening direction, is moved by such connection in a direction away from the other member, said plunger having an operative connection with said valve connected member and being operative upon energization of said actuator to move said valve through its connection with said member to an open position, resilient means acting on the other member of said pair to bias it against said valve connected member, whereby both members and said valve normally move in unison with said plunger in a valve opening direction when said actuator is energized, stop means arranged to be engaged by said other member as it moves with said valve connected member and said valve in a valve opening direc tion, thereby to arrest the opening of said valve in a partially open position until the flat surfaces of said members separate, and the areas of the normally contiguous surfaces of said members and the viscosity of said liquid in which they are immersed being such that a predetermined interval is required under the operating force of said solenoid actuator to effect a separation of said members.

5. In a solenoid valve assembly, a solenoid actuator, a normally closed valve operatively connected to said actuator and arranged to be moved to a full open position thereby when said actuator is energized, detent means for momentarily detaining said valve in a partially open position as it is being opened by said actuator, said means comprising a chamber, a viscous liquid in said chamber, first and second movable members in said chamber each having a flat surface immersed in said liquid and facing the surface of the other member, said members being mounted for relative movement in a plane transverse to their flat surfaces, means connecting said first member with said valve, the arrangement being such that said first member is moved in a direction tending to separate its flat surface from that of said second member as said valve moves in an opening direction, resilient means acting to bias said second member against said first member in face to face contact therewith, whereby said members normally move together with said valve in a valve opening direction, stronger resilient means acting to bias said first member in a direction toward said second member and to bias said connected valve in a closed position, stop means arranged to be engaged by said second member as said members and said valve are moved by said actuator toward a valve open position against said stronger resilient means thereby to arrest valve opening movement until the flat surfaces of said members are separated, and the area of the meeting flat surfaces of said members and the viscosity of the liquid in which they are immersed being such that a predetermined interval is required under the force of said solenoid actuator to effect separation of said members once their immersed surfaces have been moved into a predetermined proximity, and means on one of said members for limiting the approach of said surfaces under the action of said resilient means to said predetermined proximity.

6. In a solenoid operator for valve actuation, a solenoid winding, a reciprocating plunger having a returned position and an energized position to which it moves upon energization of the solenoid winding means tending to momentarily arrest the movement of said plunger as it moves from its returned to energized position comprising a chamber containing a viscous liquid, a pair of members each having a flat surface immersed in said liquid and arranged face to face with that of the other, said members being mounted for transverse movement of their flat surfaces in said liquid, means limiting the movement of one of said members over that of the other, means movable with said plunger arranged to engage the other member to move it in a direction away from said one member as said plunger moves from its returned to energized position, resilient means acting to bias said other member against said one member and to bias said plunger in its returned position, and the areas of the meeting flat surfaces of said members and the viscosity of the liquid in which they are immersed being such as to require a predetermined interval under the operating force of the solenoid when energized to efiect a separation of said members once their surfaces have been moved into contact by said resilient means.

7. In a solenoid valve assembly, a normally closed valve, a solenoid valve operator including a reciprocating plunger having a returned position and an energized position, means forming a chamber, a viscous liquid in said chamber, a pair of members each having a fiat surface immersed in said liquid and arranged face to face with the fiat surface of the other member, said members being mounted for transverse movement of their fiat surfaces in said liquid, means movable with said plunger engaging one of said members to move it in a direction tending to separate its fiat surface from that of the other member as said plunger moves from its returned to its energized position, a first resilient means biasing said other member in surface-to-surface contact with said one member, whereby said other member normally moves with said one member as it moves with said plunger to an energized position, a second resilient means acting on said one member to bias it against said other member and to bias said plunger to its returned position, means forming a connection between said one member and said valve to cause the full opening of said valve as said one member is moved with said plunger to an energized position, and means limiting the movement of said other member to less than that required to permit it to move with said one member to a full valve open position, whereby opening movement of said valve is interrupted until the surfaces of said members are separated.

References Cited in the file of this patent UNITED STATES PATENTS 830,537 Statter Sept. 11, 1906 2,920,254 Ray Jan. 5, 1960 2,931,617 Jamieson Apr. 5, 1960

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