US2799293A

US2799293A - Quick exhaust valve

Info

Publication number: US2799293A
Application number: US405226A
Authority: US
Inventors: Robert B Clay
Original assignee: Skinner Chuck Co
Current assignee: Skinner Chuck Co
Priority date: 1954-01-20
Filing date: 1954-01-20
Publication date: 1957-07-16
Anticipated expiration: 1974-07-16

Description

Filed Jan. 20, 1954 FIG] Q FIG. 2

(' 3020 ifiz z 0 v 74 i INVENTOR.

T FIG-3 9 ROBERT 15. CLAY 5a 9 BY j 74 54 AT OPNEY5 QUIQK EAUFJT VALVE Robert Clay, New Britain, Conn, assignor to The Skinner Chuck Company, New Britain, Conn, a corporation of Connecticut Application January 20, 1954, Serial No. 465,226

6 Claims. (Cl. 137620) The present invention relates to solenoid-actuated valves and particularly to an improved exhaust system for a fluid control valve of the solenoid-actuated type.

Certain solenoid-operated fluid handling valves are advantageously designed for compactness, ruggedness and dependability by providing a valve member in the armature itself of the solenoid and providing a corresponding flow passage and valve seat for the same in the pole piece of the solenoid with which the armature cooperates. This provides an eflicient combination of mechanical and electrical functions of the valve, and contributes greatly to its simplicity and compactness.

In so-called three-way valves of this type, wherein the passage in the solenoid pole piece provides one of two alternate connections to a common passage, the pole piece passage often comprises an exhaust or return passage for fluid handled by the valve, the common passage being connectible to either this exhaust or to an alternative pressure inlet passage, depending on whether the solenoid is energizedor not.

With such an arrangement, the valve may be employed, for example, to control the position of a power piston in a working cylinder connected to the common passage, the piston position being varied in accordance with the connection of the common passage to either the pressure input passage or exhaust side of the valve. When the valve is so employed, it is an important consideration from the standpoint of speed and sensitivity of control that the fluid pressure in the common passage be decreased when the common passage is connected to the exhaust side of the valve as swiftly as it is increased when connected to the pressure side. With the type of valve construction above referred to, that is, with the exhaust port being provided directly in the pole piece of the solenoid and its cooperating valve being carried directly by the solenoid armature, it is difficult to provide an exhaust port of large size and hence pressure drop during exhausting is more sluggish than desirable. Particularly is this so in valves of the alternating current type, Where the usual shading ring must also be accommodated in the end of the solenoid pole piece opposite the armature to prevent chatter of the armature, and thus takes up some of the area of the pole piece which could otherwise be used for the exhaust port.

It is a principal object of the present invention, therefore, to providein a solenoid-operated fluid control valve of the character described, an auxiliary exhaust system which will operate automatically when the solenoid .is actuated to switch the connection of the common passage abruptly from the pressure side to the exhaust side of the valve, and will facilitate and greatly increase the rate of pressure drop in the common passage responsive to such a solenoid control signal.

Otherobjects will be in part obvious, and in part pointed out more in detail hereinafter.

The invention accordingly consists in the features of construction, combination ofelements and arrangement of parts which will be exemplified in the construction here- 2,799,293 Patented July 16, 1957 after set forth and the scope of the application of which will be indicated in the appended claims.

In the drawing:

Figure its a sectional view, taken on line 11 of Figure 3, of a'solenoid-actuated fluid control valve of the type with which the present invention is particularly suitable, provided with an auxiliary exhaust system constructed in accordance with the present invention;

Figure 2 is an auxiliary sectional view of a portion of the structure shown in Figure 1, taken on the line 22 of Figure 3; and

Figure 3 is a bottom view to a diminished scale of the structure of Figure 1, showing the plane in which the view of Figure 2 is taken.

Referring to the drawing, a fluid control valve of the type with which the present invention is particularly suitable includes a base 2 on which is supported a solenoid 4 including an electromagnetic coil 6 enclosed within a casing 8 connected to the base. The solenoid has a pole piece 10 of magnetic material which is bored out axially to provide an exhaust passage 12 for the valve, terminated at its outer end in an exhaust port 14 and at its inner end in a valve seat 16 projecting from the pole piece. Extending axially from the inner end of the pole piece It is a sleeve-1'8 of non-magnetic material within which is slidably. supported a plunger 20 or armature for the solenoid. Plunger 2t) fits loosely in sleeve 18, so that fluid may flow along the plunger between it and the sleeve. If desired the plunger may be fluted or slotted lengthwise to better accommodate such fluid flow. At its end adjacent the pole piece 10 the plunger is provided With an insert 22 of rubber or the like which serves as a valving member and makes a good seal with the valve seat 16. Concentric with the valve seat 16 and exhaust passage 12 is a slot in the pole piece containing the usual shading ring 24 of copper or other highly conductive material. As is well known, the shading ring 24 produces by induction a magnetic field out of phase with the field developed by the coil 6, and this auxiliary field fills in the gaps in the main fieldand prevents chatter of plunger 20 when solenoid 4 is energized and the plunger is drawn up against pole piece 10..

At its end remote from thepole piece, plunger 20 has a flange 26 which retains a spring 28, the other end of which acts against sleeve 18 and urges plunger 20 in a downward direction away from the polepiece.

The base .2 is provided with a cylindrical chamber 38 for receiving the flanged end of plunger 20. The bottom of chamber 30 is recessed to accommodate an annular valve seat 32, which is apertured to connect chamber 30 with a drilled passage 34 and another drilled passage 36 which leads to an inlet port 38 in the base. Together, the

drilled passages

34, 36 and the aperture in the valve seat comprise an. inlet passage, which may be connected at inlet port 38 to any suitable source of pressurized fluid. Opposite valveseat 32 the plunger 29 carries a flexible insert 40 of rubber or the like which serves as a valve to close off chamber 39 from the inlet passage. Thus it will be recognized that plunger 20 serves as a'b'i-positional valve member which. controls the connection of chamber 36 Withjeither the inlet passage or the exhaust passage, in accordance with the de-energizationor energization of solenoid 10.

Also provided in base 2 is an outlet port 42 which is adapted to be connected, for example, to a working cylinder, not shown, whose piston can thereby be controlled by the valve. Leading from the chamber 30 to the outlet port 42 is the common or outlet passage of the valve, which. is provided in the base and includes a drilled passage 44' leading away from chamber 30, as particularly shown in Figure 2, and joined to anothervdrilled passage 46 connecting with a cavity 50. Also included in the outlet passage, in the side of the cavity 50, is a construction formed by a port 52 of restricted size, which connects to outlet port 42 as shown in Figure 1.

The bottom end of the cavity is closed by a plug 54 held in place by a snap ring 56, and carrying a flexible seal 58 which makes the closure fluid-tight. The top end of the cavity is recessed into the base 2 to accommodate a valve seat 60 apertured to connect cavity 50 with a drilled passage 62 in the base. Drilled passage 62, in turn, communicates with another port 64 in base 2, hereinafter referred to as the quick-exhaust port.

Slidably supported within cavity 56 is a free piston 66 whose sides make a substantially fluid-tight seal with the walls of cavity 50. On its downstream side, i. e. the side furthest removed in the fluid flow path from chamber 30, the piston 66 is recessed to accommodate an insert 68 of flexible material, which serves as a valve to close against valve seat 66 when piston 66 is displaced in a downstream direction. The piston 66 is reduced in diameter at its waist to provide an upper piston ring 70 and a lower piston ring 72. The reduced diameter portion of the piston forms an annular space 74 which communicates with port 52, and the lower piston ring 72 has a plurality of small slots 76 in its periphery which provide a passage having a flow area, i. e. cross-sectional area, substantially larger than the cross-sectional area of port 52. Slots 76 thus insure a connection at all times from the upstream side of piston 66 to port 52 and thence to the outlet port 42. Also communicating with outlet port 42 is a port 80 which connects to cavity 50 on the downstream side of piston 66. This port 30 is sized so as to have a flow area smaller than slots 76 but substantially in excess of the flow area of the port 52. The reason for this relationship of flow areas will become apparent hereinafter.

In the operation of the valve, when solenoid 4 is energized, plunger 26 is lifted against the force of spring 28, which opens chamber 30 to the inlet passage and closes valve 22 against valve seat 16 to close oif chamber 30 from the exhaust passage 12. Fluid under pressure connected to inlet port 38 is thereby allowed to flow into chamber 30 and through the drilled

passages

44, 46 of the common or outlet passage to the upstream side of piston 66 in cavity 50. From this point the fluid flows through slots 76 in lower piston ring '72, into annular space 74 at the waist of the piston, and through port 52 to outlet port 42, from where it may be directed in any desired manner. The pressure drop incurred in the fluid during its flow through the small port 52, which is further increased by its partial obstruction by piston ring 70, is sufficient to produce a substantial pressure diflerential between fluid at the upstream side of piston 66 and fluid communicated to the downstream side of the piston through the port 86. For this reason piston 66 is quickly displaced in a downstream direction to seat the valve 68 on the valve seat 60 and close oflE quick exhaust port from cavity 50.

When it is desired to connect outlet port 42 to the exhaust side of the valve, the solenoid 4 is de-energized. This permits plunger to drop down in the sleeve under the influence of spring 28, and close off the inlet passage from chamber 30 by the seating of valve 40 on valve seat 32. This simultaneously opens the exhaust passage 12 by unseating valve 22 from valve seat 16 and, since a fluid flow path of substantial area is provided along the sides of plunger 26, fluid can exhaust from chamber 36 out the exhaust passage 12 in the solenoid pole piece 10. Fluid therefore exhausts from outlet port 42 through port 52, the slots 76 in lower piston ring 72, and the two

drilicd holes

44, 46, and thence out exhaust passage 12.

It will be appreciated, however, that the size of the pole piece and the necessity for maintaining the greater port on of its end area intact for magnetic attraction of the plunger, definitely limits the size of the exhaust passage in the plunger, at least at its inner end. Particularly is this true when the available area of the end of the pole piece must also accommodate the shading ring, as is the case with alternating current solenoids. The limited size of the exhaust passage in this solenoid pole piece may therefore render the exhausting of fluid from the chamber substantially slower than is desirable, particularly when the valve is employed for hydraulic control purposes where speed and sensitivity of response to control signals are of course important.

In accordance with the present invention, an arrangement is provided to throw open the auxiliary or quick exhaust port 64 automatically in response to the opening of the regular exhaust passage 12 by the solenoid 4. Opening of the quick exhaust port 64 provides an additional exhaust path which is efiectively in parallel with the regular exhaust passage 12 for the outlet port, and thereby enables an exhausting and a reduction in pressure of the fluid from the outlet passage with much greater speed than has heretofore been possible.

The quick exhaust port is opened in the following manner: As previously explained, when outlet part 42 is connected to chamber 30 by energizing of solenoid 4, piston 66 is displaced in cavity 50 in a downstream direction by the excess pressure on its upstream side, and thus closes off the quick exhaust passage. Conversely, when the regular exhaust passage 12 is opened and fluid begins to flow in the reverse direction from outlet port 42 through the port 52 and through slots 76 toward exhaust passage 12 in pole piece 10, the restricted size of port 52 creates a pressure drop which lowers the pressure on the upstream side of piston 66 to a level substanially below the pressure in outlet port 42. The pressure on the downstream side of the piston, however, is not lowered by any such pressure drop, and hence substantially exceeds the pressure on the piston upstream side. This pressure differential created between the downstream and upstream sides of piston 66 is developed substantially instantaneously after the exhaust passage 12 is opened, and is of suffl-cient magnitude as to displace piston 66 in the upstream direction, even though the annular area of piston 66 surrounding valve seat 60 which is exposed to this downstream fluid pressure is smaller than the area of the upstream side of the piston. Displacement of piston 66 in the upstream direction further restricts port 52 with piston ring 70, and thus further increases the pressure differential on piston 66, to give a positive quick opening of valve 68. This connects the quick exhaust passage to outlet port 42 through cavity 50 and port 80. After the quick exhaust passage is opened, there is of course some pressure drop through port 80 due to exhaust flow therethrough. This pressure drop tends to reduce the pressure on the downstream side of piston 66 somewhat and thus lessens the pressure difierential between the downstream and upstream side. However, so long as there is even a slight pressure difierential between the downstream side and upstream side of piston 66, the piston will remain displaced in the upstream direction to keep the quick exhaust passage open, because, once piston 66 is initially displaced enough to lift value 68 from valve seat 66, the entire area of the downstream side of the piston becomes exposed to the pressure of the fluid at the downstream end of cavity 59.

With the quick exhaust passage being thus opened automatically substantially immediately after the opening of the regular exhaust passage 12, it will be appreciated that the pressure at outlet port 42 is enabled to fall much more rapidly than if the flow of exhausting fluid were confined to the regular exhaust passage in pole piece 10 and limited by its small area.

Thus, with the arrangement provided by the present invention, the speed with which conditions at the outlet port can be varied in response to control signals to the solenoid is greatly increased, and the flexibility and sensitivity of the valve as a control device are greatly enhanced. Moreover, these advantages are attained by an arrangement whose operation is fully automatic and responsive exclusively to the control of the valve with the solenoid in the usual manner, so that no additional control apparatus is required.

As many changes could be made in the above construction and many apparently widely diflrent embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the language used in the following claims is intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

I claim:

In a fluid control valve assembly of the type having an inlet, an exhaust, and an outlet adapted to be connected alternatively to said inlet or said exhaust, means for facilitating rapid reduction in pressure at said outlet responsive to its connection to said exhaust comprising an auxiliary exhaust, a check valve connecting said auxiliary exhaust to said outlet, said check valve being adapted to close said auxiliary exhaust responsive to excess pressure on its upstream side and open said auxiliary exhaust responsive to excess pressure on its downstream side, and a permanently open constriction in said outlet connected at its upstream end to the upstream side of said check valve and connected at its downstream end to the downstream side of said check valve, whereby the pressure diflerential across said restriction is applied across said check valve and pressure on the downstream side of said check valve overcomes pressure on its upstream side and opens said auxiliary exhaust responsive to connection of said outlet to said exhaust.

2.- In a fluid control valve assembly of the type having an inlet, an exhaust and an outlet adapted to be connected alternatively to said inlet or said exhaust, means for facilitating rapid reduction in pressure at said outlet responsive to its connection to said exhaust comprising an auxiliary exhaust, a pilot piston in said outlet adapted to be displaced in a first direction responsive to excess pressure on its upstream side, a valve carried by said piston for closing said auxiliary exhaust responsive to displacement of said piston in said first direction, a permanently open constriction in said outlet adapted to create a pressure differential between its upstream and downstream ends responsive to fluid flow in said outlet, a first passage connecting the upstream end of said constriction to the upstream side of said piston, and a second passage connecting the downstream end of said constriction to the downstream side of said piston, whereby when said outlet is connected to said exhaust said constriction creates a pressure on the downstream side of said piston in excess of pressure on its upstream side and displaces said piston opposite to said first direction to open said check valve.

3. In a fluid control valve assembly of the type having inlet, exhaust, and outlet passages, and a valve member connecting said outlet passage alternatively to said inlet passage or said exhaust passage in accordance with control signals supplied to a solenoid, an auxiliary exhaust system for rapidly exhausting said outlet passage responsive to connection thereof to-said exhaust passage comprising a cylindrical cavity in said outlet passage, a free piston in said cavity adapted to be displaced downstream therein responsive to connection of said outlet passage to said inlet passage, a first port in said cavity connected at one end to said outlet passage downstream of said cavity and connected at its other end to the upstream side of said piston, a second port in said cavity connecting the downstream side of said piston to' said outlet passage downstream of said piston, said second port having a larger flow area than said first port, whereby pressure drop in said first port responsive to exhausting of said outlet passage through said exhaust passage exceeds pressure drop in said second port and fluid pressure on the downstream side of said piston overcomes fluid pres sure on its upstream side to displace said piston in an upstream direction, an auxiliary exhaust port in said cavity, and a valve on said piston for opening said auxiliary exhaust port when said piston is displaced upstream.

4. In a fluid control valve asesmbly of the type having an inlet passage, an exhaust passage, an outlet passage, and a bi-positional valve member connecting said outlet passage alternatively to said inlet passage or said exhaust passage in accordance with control signals supplied to a control solenoid, an auxiliary exhaust system for rapidly exhausting said outlet passage responsive to connection thereof to said exhaust passage comprising a cylindrical cavity in said outlet passage, a free piston in said cavity adapted to be displaced downstream therein responsive to connection of said outlet passage to said inlet passage, a first port in said cavity connected at one end to said outlet passage downstream of said cavity and connected at its other end to theupstream side of said piston, a second port in said cavity connecting the downstream side of said piston to said outlet passage downstream of said piston, said second port having a larger flow area than said first port, whereby pressure drop on the upstream side of said piston responsive to exhausting of said outlet passage through said exhaust passage exceeds pressure drop on the downstream side of said piston and displaces said piston in an upstream direction, a piston ring on said piston adapted to partially restrict said one end of said first port responsive to upstream displacement of said piston to decrease the flow area of said first portion and increase the pressure drop on said piston upstream side, an auxiliary exhaust port in said cavity opposite the downstream side of said piston, and a valve on said piston for opening said auxiliary exhaust port when said piston is displaced upstream.

5. In a fluid control valve assembly of the type having inlet, exhaust and outlet passages, and a bi-positional valve member connecting said outlet passage alternatively to said inlet passage or said exhaust passage in accordance with control signals, an auxiliary exhaust system for automatically supplementing said exhaust passage responsive to connection of said outlet passage thereto comprising a cylindrical cavity, a free piston in said cavity, an auxiliary exhaust port connected to said cavity, a valve carried by said piston adapted to close said auxiliary exhaust port when pressure on one side of said piston exceeds pressure on its other side, a constriction in said outlet forming a diminished flow area therein, a first flow passage connecting the upstream end of said constriction to said one side of said piston, and a second flow passage connecting the downstream end of said constriction to the other side of said piston, said first and second flow passages having a substantially larger flow area than the area of flow past said constriction, whereby pressure on said other side of said piston overcomes pressure on said one side of said piston responsive to connection of said outlet passage to said exhaust passage and displaces said piston to open said valve.

6. In a fluid control valve assembly of the type having an inlet passage, an outlet passage, a control solenoid, an armature adapted to be reciprocated by said solenoid, an exhaust passage in the pole piece of said solenoid, and valves carried by said armature for connecting said out let passage alternatively to said inlet or said exhaust passage responsive to control signals supplied to said sole noid, means for facilitating rapid reduction in pressure in said outlet passage responsive to its connection to said exhaust passage comprising an auxiliary exhaust connected to said outlet passage, a piston in said outlet passage, a restriction in said outlet passage adapted to create a pressure diflerential therein, passages connecting opposite ends of said restriction to opposite sides of said piston to displace said piston downstream responsive to admission to said outlet passage of fluid from said inlet passage, and a valve carried by said piston for closing said auxiliary exhaust responsive to downstream displacement of said piston, whereby said restriction creates a reverse pressure difierential across said piston responsive to connection of said outlet passage to said exhaust passage and d valve.

isplaces said piston upstream to open said References Cited in the file of this patent