US2211646A - Valve - Google Patents

Description

Aug. 13, 1940. COLE 2,211,646

VALVE Ill" Filed March 22, I958 2 Sheets-Sheet 2 I 25 A 1' I, J 2 97/ 102 .4! I 1% 104 (4 i 102 3.9 r 12 M/A II Patented Aug. 13, 1940 UNHTE STATES VALVE Lorne A. Cole, Brantford, Ontario, Canada, assignor to Waterous Limited, Brantford, 0n-

tario, Canada Application March 22,

4 Claims.

This invention relates to improvements in control valves and a controlling means therefor.

An object of the invention is to provide a control valve designed to control the pressure particularly in a hydraulic system which will operate smoothly and will react quickly to pressure variations.

A further object of the invention is to provide a valve of particularly simple design which will permit a very gradual feeding of the pressure medium or the full volume of the pressure medium as required.

A still further object of the invention is to provide a construction wherein leakage of the pressure medium through the valve will be returned to the system.

A still further object of the invention is to provide a device of this character which, due to its design, may be manufactured at relatively low cost.

The invention will be understood by reference to the following detailed specification taken in conjunction with the accompanying drawings In the drawings,

Figure 1 illustrates a front elevation of an electric governor with the valve mounted thereon and connections therefor including pilot valves to illustrate one manner in which the valve may be employed.

Figure 2 is a side elevation of Figure 1.

Figure 3 is an enlarged longitudinal section taken through the valve structure and showing thereabove, compensating mechanism which may function between the valve and an electrical system of a governor.

Figure 4 is a longitudinal section taken through an alternative form of valve structure which'is adaptable for single pressure systems.

Referring to the drawings F indicates the control valve structure through which the hydraulic pressure medium for instance water, is passed to supply a pulp grinder or other mechanism being operated. The valve structure may be mounted upon an electric governor A to co-operate therewith in the control of other mechanisms. The valve casing H] is provided with a water inlet H and a water outlet l2, each of which communicates with the interior of the casing which preferably takes the form of a cylindrical bore l3 within which is disposed the movable valve member M of valve F which takes the form of a hollow piston slidably fitting within the bore it. The movable member or valve piston I4 is of particularly simple structure, as compared with the structures in the prior patents referred to, and

1933, Serial No. 197,536

only involves the use of one cylindrical member which is caused to move upwardly or downwardly in the casing to establish or cut off communication between the inlet H and outlet !2 of the casing or to increase or reduce the degree of their communication.

The valve is operated by means of pipe connections [5 and I6, which will permit the passage of fluid to and from the valve being controlled, as for instance by mechanical pilot valves D and E, the former serving to feed pressure medium to the valve F and the latter withdrawing it therefrom in accordance with the operation of the mechanism of the governor. of fluid to the valve F or its withdrawal therefrom will cause the valve piston it to raiseor lower as required. The valve piston M is provided with a series of water inlet orifices H and a plurality of water outlet orifices ill, the first series being positioned so that they may be gradually brought substantially into registry with the inlet I! of the valve casing, while the second series are positioned so that they are always in communication with the water outlet l2, provision being made so that Water may be gradually fed into the valve casing iii and regardless of the extent to which the valve is raised the orifices l 3 will always provide for an exit through outlet iii. For instance, the outer surface of the valve piston I4 is provided with an annular tapered groove adjacent to and intersecting the orifices H and the deepest part of the groove registers directly with the inlet orifices ll. Consequently, when the valve piston M is raised to a limited ex-- tent, the upper extremity of the groove l5 will come into registry with the water inlet and per mit a proportionate amount or minimum quantity of water to flow into the interior of the valve piston 14. The water discharges from the interior of the valve piston l4 via the outlet orifices it, which communicate with a recess formed by an annular groove 20 in the exterior of the valve piston M in an area overlying the outlet orifices I8 and of a width such that when the valve piston I4 is raised to a varied extent during operation the annular groove 251 will at all times provide for communication between the outlet it of the casing and the outlet N3 of the valve M.

The inlet II and outlet I2 are specially formed so as to arrange for the entry and discharge of water in such a manner as to produce practically balanced conditions. For instance, circular cored spaces 2! and 22 are provided respectively in an area registering with the inlet H and the outlet [2 so that in the case of the inlet, for instance,

The supply 7 water passes through the inlet I I around through the cored space 2| and discharges into the interior of the valve casing by means of the plurality of inlet apertures 23. In the case of the discharge IZ the water discharges through the openings I8 and through openings 24 in the valve casing communicating with the cored spaces 22 and thence out through the discharge I2. In this manner there is a balanced pressure on the piston and no side thrust takes place due to the rushing of water through the openings 5 I and I2, as would otherwise tend to be the case if the cored spaces 2I and 22 were not provided. These spaces are readily accessible, in the case that they should become plugged, by providing a series of openings 25 which may be filled by screw pipe plugs to enclose these spaces completely.

It will be apparent that the valve structure F is of particularly simple construction embodying one movable part which is enclosed in a single chamber through which there is little possibility of leakage even when excess pressure is built up within the valve casing and even when the plunger or valve piston I4 becomes worn. Under these conditions leakage water passes upwardly from orifices 23 between the valve piston and walls of the casing into the space above the valve piston and is returned into the system through the apertures 25a in the top of the piston valve I4. Thus undue operation of the piston through leakage reflected through operation of the governing wattmeter is eliminated.

It may be particularly noted that the structure of valve F is such as to provide for a balanced pressure above and below piston valve [4. The hydraulic pressure under which the grinder is operating is present above piston valve I l while a corresponding pressure occurs below this piston valve to maintain the pressure in the hydraulic system without, however, taking into considera tion the added weight of the piston valve itself. By reason of the fact, however, that the piston valve I4 has a rod G projecting up through the top of the casing through a suitable packing the latter provides a sufficient gripping pressure on the rod to sustain the weight of the piston. Consequently there is no tendency of the piston to creep either upward or downward when the pilot valves D and E are closed and normal conditions exist. Thus, by providing for balanced pressure in the valve under normal conditions water leakage is reduced as well as consequent Wear on the parts that takes place by reason of leakage and especially if grit is present in the water. This is a decided advantage over prior structures through which water leakage caused the valve to creep and necessitated a constant compensating action through the continual opening and closing of the pilot valves which necessarily caused excess wear on all moving parts.

The rod G, which is connected to piston valve 4, and which passes up through the valve casing, enters a casing H and connects with other mechanism connected in the governing wattmeter circuit which effects a further control in the operation of valve F to prevent excessive and unnecessary operation of the latter.

As has been indicated, pilot valves D and E function to control the operation of the piston I4 of valve F. Pilot valve D functions as an increasing valve to supply water to the casing of main valve F through pipe I5 to raise the piston I4 to an increasing degree as required and receives its water supply from a pipe line connected to the source for valve F. Pilot valve E functions as a decreasing valve and decreases the pressure on the piston I4 by removing water from the bore I3 of valve F through pipe IS.

The valve piston M has a rod G which extends out of the valve casing and may connect with a dash-pot and other mechanism connected with the governor as a compensating mechanism to avoid any hunting action that may be set up by reason of sudden variations of pressure in the system.

An alternative form of main valve structure F suitable for use in single pressure systems such as illustrated in Figure 4, and which will have a quick response may be employed. This has an automatic quick-closing or quick-opening action without the use of auxiliary pilot valves. The structure of this valve is somewhat similar to that disclosed in Figure 3, having an outer casing 9| formed with an inlet opening 92 and outlet opening 93, the interior of the casing having a cylindrical bore 94 to receive the normal actuating piston valve 95, as well as a further valve member referred to hereinafter.

In this structure the piston valve 95, which constitutes the normal movable member of valve structure F, is provided with inlet apertures 96 and discharge apertures 97. The inlet apertures have associated therewith an annular inwardly sloped groove 98 while the outlet apertures have associated therewith an annular groove 99 in the outer surface of the piston so that, as in the case of the other pressure control F previously described, the water may be gradually introduced to the valve structure and is constantly passed out through the discharge opening 93 regardless as to what height the valve may be raised. In this form of structure, however, the valve 95 is further encased by an auxiliary sleeve valve I JO which is formed with inlet apertures Illl through which the water entering through inlet 92 must pass to enter this general valve structure F, whereas valve I00 is also formed with discharge apertures I02 through which the water must pass to discharge through the outlet 93. The auxiliary sleeve valve I00 is formed also with annular grooves I03 and I54 in its outer surface at a position directly overlying the position of the orifices I 0! and I92 respectively and these grooves are of such a width as to provide for registry of a part of the grooves with the inlet 92 and outlet 93 respectively regardless as to what height the sleeve valve I00 may be raised.

The sleeve valve I00 has projecting from its top a tube I05 which permits the rod G to pass therethrough for connection to the compensating mechanism previously described and surrounding the tube I 05 is a strong compression spring I06 which bears upon the top of the auxiliary sleeve valve at one end, at the other, upon a bar or yoke I01 which is rigidly mounted on posts I08 and use extending outwardly from the valve casing F. The compression spring I66 exerts a downward pressure upon the sleeve valve IGELtending to keep it in its lowermost position. Assuming that the valve piston 95 is raised to an extent to permit a minimum flow of water through the valve F to maintain the grinder under normal operating conditions and assuming that at this point the operator throws a valve on the grinder to retire a pocket which has become empty, the pilot valve D will function to raise valve piston 95 in response to the signal from the wattmeter C for more load due to pressure drop on the legs but this will not be as quick an operation as is required for this emergency. However. it will be apparent that when the sudden drop of pressure in the system occurs by reason of the operator retiring the pocket, the pressure normally transmitted to the top of sleeve valve 100 through the orifices H19 in the top of valve piston will naturally drop and the coil spring I06 will immediately lower sleeve valve Hill so that its apertures I09 will register immediately on a lower portion of groove 98 of the piston valve 95 so that immediately all available pressure is transmitted through the valve structure F to the grinder. In fact, the abnormal drop in pressure in the hydraulic system and consequent drop of pressure within the valve structure F will cause the valve I00 in efiect to operate slightly before the operation of the valve piston 95 through the pilot valve D, so that the sleeve valve gives a very instantaneous action in throwing open the ports to admit all available pressure.

In the case where the pocket has been completely retired and the abnormal pressure requirement is satisfied, a pressure build-up will immediately occur in the hydraulic system which will immediately act upon sleeve valve Hi6 to raise it very quickly against the pressure of spring I06 so that the apertures I0! will start to move away from registry with groove 98 in valve piston 95 slightly prior to the shutting oif of pilot valve D and the opening of decreasing pilot valve E. Consequently upon the downward movement of valve piston 95 responsive to the action of the decreasing pilot valve E the apertures NH of sleeve valve I00 and the groove 98 of valve piston 95 will be moved nearly out of registry in a very quick space of time. Thus, the pressure buildup is dissipated and the valve structure F commencs to function again normally to take care of the narrower variations in pressure which occur when the grinder is grinding under normal conditions.

In this structure it will be noted that the post 59 and post 64 may be supported by means of a suitable cross head H0 supported from the tube It will be apparent from the foregoing description of the various forms of construction which may be employed that the governor will act quickly and eiiiciently to maintain substantially balanced conditions in the hydraulic pressure system of the device or devices to which it may be connected to control regardless as to whether the governor is operating in conjunction with a double pressure system or a single pressure system.

It will be appreciated, of course, that while the structure involved has been described generally as applied to controlling the operation of pulp grinders it is equally applicable to other devices employing an electric motor and hydraulically operated mechanism.

I claim:

1. A control valve for hydraulic pressure systems and the like comprising a valve casing having inlet and outlet ports, a hollow valve piston controlling communication between said inlet and outlet ports, said valve piston having an inwardly tapered circumferential groove and a series of radial openings disposed between the inside of said piston and the groove, said groove forming means to vary the inlet flow of pressure medium and a circumferential groove, with a series of radial openings between the inside of the piston and said latter groove said latter groove being of sufficient length to allow complete communication between the inside oi the piston and the outlet port throughout operation or" the piston.

2. The device as claimed in claim 1 in which the openings between the inside of the piston and the tapered groove are positioned to intersect the tapered groove at its deepest part.

3. A control valve for hydraulic pressure sys tems comprising a Valve casing having an inlet port and an outlet port, a valve piston, having a solid base, controlling communication between the inlet port and outlet port, said valve piston being hollow and having an inlet opening and outlet opening designed to be brought into registry with said inlet and outlet ports respectively, to permit flow of the pressure medium through the valve, a fluid inlet at the base of the casing permitting entry of pressure medium, said pressure medium acting upon the solid base of the valve to bring said ports and openings into registry and to move them out of registry, a sleeve valve within the casing surrounding said valve piston and having inlet and outlet apertures designed to register with said inlet port and outlet port of the valve casing and to be brought into and moved out of registry with the inlet and outlet openings of the valve piston respectively upon predetermined relative movement between the valve piston and the sleeve valve carried by the pressure medium.

4. A control valve for hydraulic pressure systems according to claim 3 in which the said inlet and outlet apertures of said sleeve include cir-

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