US1786474A - Pump-regulating valve - Google Patents

Description

DeC- 30, 1930- H. F. BlcKEl.

PUMP REGULATING VALVE F'ileq Aug.

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Patented Dec. 30, 1930 UNITED STATES- PATENT OFFICE HENRY E. BIcKEr., or PLAINFIELD, NEW JERSEY, AssIGNOR rro TEE NEW YORK AIR BRAKE COMPANY, A CORPORATION or' NEW JERSEY PUMP-REGULATING VALVE Application led August 15, 1928. Serial No. 299,795.

This invention relates to valves for controlling pumps, particularly direct connected steam actuated air compressors such as are used in air brake and similar service.

For simplicity in explaining the invention,

I shall refer to it as applied to a direct connected steam driven air pump, but it must be understood that other motive fluids may be used instead of steam, and that it is not necessary that the compressor deliver air, as the device would develop utility with other fluids.

Heretofore it has been proposed to control the action of the pump while discharging against a low back pressure such as is encountered when the pump first starts to charge the reservoir, byproviding a motor subject to reservoir pressure, and connecting this motor to a valve which throttles the flow of motive steam. The parts are so arranged that until a substantial back pressure is built up, thus imposing supicient load on the pump mechanism to keep it from running away, the flow of motive steam to the pump is throttled.

The prior art devices have been gradual or progressive in their action, with the result that the steam flow is throttled over quite a Wide range of reservoir pressure. This results in waste of steam and generally unsatisfactory action, so that the devices of this sort have not come into general use particularly in air brake service Where it is important that the pump operate at full capacity throughout a. wide range of reservoir pressures.

The present invention provides a device which is not progressive but is sudden in its motion. Thus while the valve Operates 40, to throttle the steam liow in a definite degree below the chosen critical low pressure in the reservoir, it Opens the steam passage wide as soon as the reservoir pressure passes this valve, and maintains it wide open as long as the pressure exceeds this value, and in fact until it falls decidedly below the critical value.

Inasmuch as the reservoir is never bled to this low value in the ordinary operation of t-he brake system the eect is to prevent the pump from pounding when it lirst starts to charge the reservoir, and thereafter permit entirely free operation of the pump throughout the normal operation of the system.

V@ther features of invention reside in details of construction; among others, in the combination of the valve mechanism with a manually operated throttle valve.

The preferred embodiment of the invention is shown in the drawings in which,-

Fig; l is a section on the line l-l of Fig. 2. Fig. 2 is a section on the line 2-2 of Fig. l. The body of the valve mechanism is cast in one piece and includes a number of chambers which will hereafter be mentioned in detail.

7 is a threaded nipple by which the valvebody is connected to a steam boiler or other source of motive fluid. -8 is a valve seat and 9 is a valve coacting therewith and controlling ilow from the boiler to the chamberv 1.1. Lubricatingoil may be fed to the chamber by any suitable lubricating means connected to the threaded port 12.

The valve 9 is actuated by a stem 13 which is threaded in and guided by a bonnet la having a. packing gland V15. The bonnet 14; is screwed into the body G in a familiar manner, the structure so far described being merely a globe throttle Valve of ordinary form. The valve is operated by a hand wheel 16.

Leading from the chamber ll is a tubular discharge connection 17 which leads to the steam inlet of a steam motor forming part of the air pump unit, not shown.` The connection is conveniently made by union 18, but the pump mechanism being familiar to those skilled in the art is not illustrated.

Tntersecting the connection 17, at right angles thereto, is a tubular housing 2l for the automaticl throttle valve, which is of the balanced piston type. The bore of the housing 2l is slightly greater than the bore of the tubular connection 17, and serves as a guide for a piston valve, indicated generally by the numeral 22. This valve member has peripheral iange members 28 at its ends and between these flanges, a reduced portion or groove 24. The flanges 23 make a close sliding iit with the bore of the'chamber 2l and when the valve member 22 is to the right relatively to Fig. 2, the groeve 24 offers the sole path ot steam flow fromthe chamber 1l to the steam motor of the pump. Onrthe other hand, when the valve member 22 moves to its eXtreme lett position it is completely out of the path of steam flowY and thus permits such tlow to occur Without any throttling Whatever. The valve 22 is urged to the right, or throttling position, by a coil spring 25 Which seats against the cap 26. This cap isV threaded on to the cylinder 21 and serves to seal the left end of the cylinder. Y Y' Alined with the bore of the chamber 21 is a motor cylinder 27,.of somewhat larger diameter, and containing a piston 28 Whose rod 29 passes through a guidewayin the head 31, and acts in thrust against the endV of the valve member 21. VThe head 31 is threaded into the right hand end ot the chamber 21, and the rod 29 makes a close sliding tit With the guideway inthe head 31 so that leakage is substantially prevented. Then the piston moves to its left hand position the valve surface 32 on the piston seals against a seat 3.3 on the head 31. The space Within the cylinder 27 to the left of piston 28 is vented to atmosphere at 34 so that this space is always at atmospheric pressure and any steam leakage which may occur passes immediately to atmosphere. Y

The piston 28 is provided With a sealing ring 35 and: With a plurality of sealing grooves 36. On its right face it is formed with aprojecting rib 37, which in the right hand position of the piston, seats on a gasket 88 held in a recess in the head 39. The head 39 is screwed on to the end of the cylinder 27 and has a threaded connection 41 to which is connected a pipe, not shown, which conveys to the space at the right of the piston 28 the back pressure against Which the pump Works. In other Words port 411 is connected either to the air discharge passage of the pump or t0 the reservoir into Which the pump is charging.

In air brake systems it is preferred to connect the main reservoir to the port 41. It will be observed that When the piston 28 is in its right hand position, as shown in Fig. 2, rih 57 main reservoir pressure.

The annular space outside rib 3 seals against the gasket 38 so that only a comparatively small portion of the total. area of the piston 28 is subject to pump discharge or The annular space on the piston outside of the rib 37 is vented to atmosphere by Way of the lay-pass port 42 which leads around the edge of the piston 28 when this is in its extreme right hand position, but at all other times is functionless.

The operation of the device is as follows:

Assume that the main reservoir is not charged. Under such conditions the spring 25 will force the valve 22, and consequently the piston 28, to the extreme right hand position, causing rib 37 to seat on gasket 38. 7 and tl e space within the cylinder 27 to the lett of piston 28, will be at atmospheric pressure. The engineer now starts the pump by opening the valve 9. Steam will Aflow to the pump by Way of the restricting groove 211, thus putting the pump into action. T he flow of steam, however, will he so throttled that the pump Will not pound, despite the tact that it is operating against virtually' no back pressure. rlhe operation of the pump will cause pressure in the reservoir to rise and consequently establish a back pressure which would be suliicient to prevent the pump from pounding. As soon as this condition has been reached, it is desirable to open the steam passage. To bring about this result the characteristics of the spring25 and the area Within and Without the rib 37 are specially coordinated. lhen the desired pressure is reached. the piston 28 will be forced slightly' to the lett against the sprinf resistance which is then at its minimum. This exposes the entire area of the piston 28 to the back pressure. The total. area ot the piston and the maximum (iully compressed) stress et the spring 25 are such that When the entire area of the piston is exposed the spring is completely overpowered.

t follows that main reservoir pressure, act ing over the entire area of piston 28 intimediately moves this piston to its extreme lett hand position in which the valve 22 clears the passagethrough the connection 17 and permits unrestricted flou' to the steam pump. From then on the pump will operate under steamfioiv and rapidly charge the main reservoir.

Under normal. conditions ot operation, pressure in the reservoir will not thereafter drop low enough to permit the valve 22 to throttle the steam flow. The result is that the valve mechanism gives the desired initial throttling action Without limiting the normal operation of the pump.

What is claimed is:

1. Means for controlling` pressure motor actuated pumps which deliver normally against a back pressure, comprising in combination, a valve interposed in the path ot motive fluid to said motor and havingl two positions, in one ot which it limits the tlc-w and in the other of which it permits 'tree flow of the motive fluid; yielding` means urefiirg` said valve to the irst nameduposition; a piston subject to said back pressure and connected to urge said valve toward the second named position 5 and means controlled by initial movement ot the parts from the firstnamed position toward the second named position to increase the effective area ot' said piston.

2. Means for controlling pressure motor actuated pumps which deliver normally against a back pressure, con'iprising, in combination, a valve interposed in the path of motive fluid to said motor and having two positions, in one of which it restricts the fiow of motive fluid and in the other of which it permits the free flow of motive fluid; a spring urging said valve to the first named position, and in said position exerting a relatively light stress on said valve; a piston subject to said back pressure and connected to .urge said valve toward the second named position; and means controlled by the initial movement of the parts from the first named position toward the second named position to increase the eective area of said piston, the elastic characteristics of said'spring and the two effective areas of said piston being so coordinated that as the spring yields under a given pressure the resulting` increased area of the piston will enable it completely to overpower the spring and move the valve to the second named position.

3. Means for controlling pressure motor actuated pumps which deliver normally against a back pressure, comprising, in combination, a valve interposed in the path of motive fluid to said motor and having two positions, in one of which it limits the flow and in the other of which it permits'free flow of the motive fluid; yielding means constantly urging said valve to the first named position; a piston having sealing means dividing its area into two portions; means subjecting one of said portions constantly to said back pressure; and means controlled by the movement of the piston to subject said other portion alternately to said back pressure or to atmospheric pressure.

4. Means for controlling pressure motor actuated pumps which deliver normally against a back pressure, comprising in combination, a valve interposed in the path of motive fluid to said motor and having two positions, in one of which it limit-s the flow and in the other of which it permits free flow of the motive fluid; a spring urging said valve to the first named position; a. piston having a rib subdividing its area into two portions; a'cylinder having a head against which said rib seats; a port for venting one of said areas when said valve is in the first named position; and a connection for conveying said back pressure to act against the other of said areas, whereby the initial movement of the piston to shift the valve to the second named position increases the piston area upon which said back pressure acts.

5. Means for controlling pressure motor actuated pumps which deliver normally against a back pressure, comprising, in combination, a valve interposed in the path of motive fluid to said motor and having two positions, in one of which it restricts the flow of motive fluid and in the other of which it permits the free fiow of motive fiuid; a spring urging said valve to the first named position and so designed as then to exert a moderate stress thereon; a piston having a rib subdividing its area into two portions; a cylinder having a head against which said rib seats; an atmospheric port arranged to vent one of said areas when the valve is in the first named position; and a connection for conveying said back pressure to act against the other of said areas, whereby the initial movement of the piston to shift the valve t-o the second named position increases the area upon which said back pressure acts, the resilient characteristics of the spring and the area of the piston within and without said rib being so coordinated that when pressure initially acting on the smaller area starts to overpower the spring, the resulting increase of piston area will be sufficient to cause the piston completely to overpower the spring.

6. Means for controlling pressure motor l actuated pumps which deliver normally against a back pressure, comprising in coinbination, a balanced valve interposed in the path of motive fiuid to said motor and having two positions, in one of which it limits the fiow and in the other of which it permits free dow of the motive fluid; a piston and opposing spring operatively connected with said valve to shift the same between said two ositions, said piston being subject to said iiaclr pressure whereby said pressure urges said valve toward the second named position; and means controlled by initial movement of the parts toward the second named position to increase the effective area of said piston.

7. A device for controlling pressure motor actuated pumps, which deliver normally against a baci; pressure, comprising in combination, a valve interposed in the path of motive fluid to said motor and having two positions, in one of which it limits the flow and in the other of which it permits free How of the motive fluid; motor means directly connected to actuate said valve, said motor means including a piston subject to the back pressure, and an opposing spring, the piston tending` to shift said valve toward the second named position; and means controlled by initial movement of the piston in shifting the valve from the first named toward the second named position to increase the effective area of the piston.

ln testimony whereof I have signed my name to this specification.

HENRY F. BICKEL.

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