US2200598A - Compressor shut-off valve mechanism - Google Patents

Description

May 14, 1940. c. B. FlTr-s 2,200,598

COMPRESSOR SHUT-OFF VALVE MECHANISM Filed July 11, 1938 lNvEN'rolL YR/L B. F/ TES H/S' ATTORNEY.

Patented Mayu, 1940 f UNITED STATES PATENT oFFicE 'COMPRESSOR SHUT-OFF VALVE MECHANISM (lyrll B. ll'itel, Ferguson, Mo., to Wagner Electric Corporation, i tion of Delaware St'. Louis, Mo., a corpora- Anpuontion Jui,` n; ipse, sei-ini No. classi" 1 claim. (l. sta-n) My invention rentes to valve mechanism and more particularly to shut-oi! valve mechanism ior unloading a compressor under certain conditions. The valve mechanism embodying my g ,l linvention is an improvement inthe valvemechanism shown in-the application of Fred H.

.Stroulb Serial No. 217,484, :Illed July 5, 1938.

One; of the objects of my invention'is to prq- '1 3 system associated @therewith or whenever the pressure in the receiver drops to a predetermined minimum value during a period when the fluid pressure-actuated system is notoperated. j lAnother object of-my-invention is ,to so `conv h struct and arrange the parts of the valve mechanism that an emcient operating valve is produced which willshut'oi! and open-the compressor intake at the'desired time.

other obieoto of my invention wm beooinetap-q 'al parent from the followingdescription taken in connection with the accompanying drawingv in which Figure 1 is a view showing my improved valve mechanism associated with a fluid com-4 pressor and a fluid pressure-actuated system; 33 and Figure 2 is a longitudinal cross-sectional view of thevalve -mechanism showing the details thereof; and Fig. 3 is a view on the line 3-3 of Fig. 2. n Referring to the drawing in detaiL'the eircompressor I, with which I have illustrated my shutoil' valve mechanism as being associated, is oi the rotary type having a stator 2 andan eccen- .tricaliy mounted rotor 3 provided with a plurality Vofhlades l (one only being shown). The stator n has an intake port 3 and an outlet port 3, the

' latter opening into an oli dome'l which is connected to a pressure tank 8 by means of a conduit 3, the dome `and tank both being considered the receiver of the compressor. The outlet of the 43 compressor has associated therewith a check valve I0 ior preventing back ilow of compressed iluid and associated with the outlet of the dome is another check valve II. The pressure tank; 3

is shown as connected by a conduit I2 with a 50 fluid motor I3 which may be employed to operate any mechanism desired, as for example, a braking mechanism. The fluid pressure employed to actuate the'l iluid motor is controlled by a valve Il in conduit I2, this'valve being shown as a M hand valve but it is understood thatother valve valve member 23.

mechanisms such as a ioot. control valve may be employed ii.' desired.

In compressors of the type described which are of well-known construction it is desirable to automatically prevent the compressor from compress- 5 ing iiuid after the fluid in the receiver has been placed under a :predetermined maximum pressure. This is best accomplishedjby shutting oi! the intake port so the'air or other uid which is being compressed by the lcompressor isnot 10 -permitted to enter the compressing chamber. It

is also desirable that the intake port not only be automatically closed at the proper time but that 1 it also be reopened whenever the pressure .in the receiver drops to a predetermined value below' l5 the said maximum.

In accordance with my invention I have pro` vvided an improved valve mechanism I3 which is associated with thecompressor intake and ythe compressor oil dome andthe fluid-pressure o system connected to the pressure tank whereby' the` desired opening and closing of the compressor -intake is accomplished. The valve mechanism comprises connected casings I3 and I1, the former being provided with a bore I3 and the latter with two bores I3 and 23. 'The casing I6 is formed with an outlet 2i communicating with the intake port 3 oi.' the compressor when the valve mechanism is mounted on the compressor and there `is also providedv an inlet port 22 (Figure 3)Y lo which is associated with asuitable aircleaner 23. Between outlet 2| and inlet 22 the casing is formed with a valve seat 24I which cooperates vwith a'slidable valve member 23 positioned in borej|3 and normallybiased oit-its seat by a 35 spring. 23 interposed between the valve member and the end ,of the 'casing. v'I'he valve member carries on one end an annular rubber element 21 A,to facilitate tight fitting of the valve member with the seat.` There is alsoa packing. cup 2B o at Athe other end of the valve member to prevent f leakage of uid past said member.

'I'he valve casing` I'I is secured to lvalve casing I3 by suitable bolts 23 (Figure 1)' so that bore I3 is in alignment with bore' I3 of valve casing 5 I6. The bore I3 communicates by means oi a passage 30 with a chamber 3i at the rear ot the This passage is normally closed by a valve element 32 preventing ilow of iluid from chamber 3| to bore I3. Withinbore 50 I3 is a Vpiston 33 carrying the valvev element 32 by a stem 3l, the piston being biased by a'spring 33 to .a position normally holding "valve element 32 seated. The piston valso carries a valve eiement'- llwhichis adapted toclose passage u Spi in when the piston is moved to the left and the valve element 32 is unseated. The bore I3 at the left of the piston is in communication with the atmosphere by a bleed passage 31. A packing element 38 seals the piston 33 and the right end of the bore is connected by a conduit 33 with conduit |2 at a point between the control valve |4 and the uid motor I3.

Within bore 20 of casing |1 is a diaphragm 40 which is normally held upon a seat 4| by a plunger 42 and spring 43. The diaphragm and seat form a valve to prevent communication between an inlet passage 44 connected to the compressor oil dome port of the receiver by a conduit 45 and a passage 46 leading to chamber 3| at the lrear of valve member 25.

The spring 43 is so designed as to hold the diaphragm against seat 4| until a predetermined pressure is built up in the oil dome and also the pressure tank, which pressure is the maximum pressure desired for the receiver. When diaphragm is unseated, a larger area will 4:csecl to maintain it in this position. The g 43 will reseat the diaphragm against the pressure in the tank when this pressure drops to a value of about ten pounds per square inch below the maximum tank pressure. For the purposes of description of the operation of the valve mechanism, the maximum pressure is considered as one hundred pounds per square inch. The spring 26 which biases the valve member to open position is also so designed that it will unseat valve member 25 against the maximum suction effect of the compressor and also permit valve member 25 to engage seat 24 when fluid pressure is admitted to chamber 3| as a result of the diaphragm 40 being moved off its seat when the pressure in the receiver is one hundred pounds per square inch.

When the valve parts are in the position shown air is free to enter the compressor and then be forced out into the oil dome and the tank. When the pressure in the oil dome andtank reaches the maximum pressure of one hundred pounds per square inch, the diaphragm 4|) will be moved oil" its seat, thereby permitting fluid under pressure to flow through passage 46 into chamber 3|. This pressure will now move valve member 25 against its spring 26 to close off communication to the compressor, causing it to run idle. If the control valve |4 should be moved to a position to cause operation of the iluid motor I3, air under pressure will be admitted to conduit 39 and become effective on piston 33 to move it to the left, thereby unseating valve 32 and seating valve 35. During the short interval that the passage 35 is open, the chamber 3| is connected to atmosphere and the pressure in the chamber may drop sumciently to cause the valve member 25 to be unseated by the action of its spring 24. However, as soon as valve element 36 becomes seated, the chamber will be again closed and pressure from the tank will cause the valve member 25 to be quickly reseated.

If operation of the fluid motor causes the air pressure in tank 8 to drop more than ten pounds per square inch, the diaphragm 40 will be forced onto its seat 4| by spring 43 so that iiuid under pressure no longer can enter chamber 3|. When the control valve |4 exhausts the fluid pressure in the fluid motor, fluid pressure acting on piston 33 will also be exhausted and the piston, under the action of the light spring 35, will be forced to the right, rst unseating valve element 36 and then, after a short interval, reseating valve element 32. During this short interval between the unseating of valve element 33 and reseating of valve element 32, the chamber 3| will be in communication with the atmosphere .by way of passages 30 and 3l, thereby relieving the high pressure in chamber 3|. The amount of uid to be exhausted from chamber 3| is very small and although the interval between the unseating of valve element 36 and reseating ofvalve element 32 may be short, passageway 30 is, nevertheless, open long enough to permit a substantial drop in the pressure of the fluid in the chamber 3|. Furthermore, the fluid pressure acting on piston 33 will never be exhausted quickly due to the fact that it must pass back through pipe 33 and out through the control valve I4 along with the fluid being exhausted from the fluid motor |3 and this will also aid maintaining the passage 3l open long enough to cause a sufficient drop in pressure in chamber 3|. The drop in pressure in the chamber permits spring 23 to force the valve member 25 away from seat 24 and again allow air to flow to the intake of the compressor. The compressor will now operate until the one hundred pounds per square inch pressure in the dome and tank is reached when the valve member will again close off the compressor intake in a manner already described.

If during operation of the fluid motor I3 the drop in air pressure in the tank 8 is less than ten pounds per square inch, then the diaphragm 40 will not be seated by the action of spring 43 and chamber 3| will not be disconnected from the air tank. Under these conditions when the control valve |4 exhausts the pressure in the fluid motor, the air pressure in chamber 3| will be relieved to atmosphere during the unseating of valve element 36 and the reseating of valve element 32 and possibly some fluid will also escape from the air tank due to the diaphragm 40 being unseated. 'Ihe drop in pressure in chamber 3| will suflicient to permit the spring 26 to move valve 25 off seat 24 and open the intake of the compressor. However, as soon as valve 32 becomes seated, fluid under pressure will again be built up in chamber 3| and the valve element 25 reseated. This momentary opening and reclosing of the intake valve, however, does not interfere with the desired operation of the valve control mechanism and the maintaining of the pressure in tank 8 within predetermined limits.

In order to insure that the air pressure in chamber 3| will be sufliciently released to allow valve member 25 to be unseated by spring 25, there is provided a small bleed ypassage 41 through the valve member which in the construction shown is approximately one forty-thousandths of an inch in diameter. This small bleed passage will not affect the closing action of the valve member since it is of such size that pressure can be built up in chamber 3| to move the valve member, After the valve member has become seated what little leakage of fluid takes place through the bleed passage enters into the intake oi' the compressor and is again placed in the dome.

In the event there should be a leak in the compressor dome or the tank which may cause a drop in the pressure in the dome or tank or both while the compressor is shut off and during the period that the fluid motor I3 is not operated, the valve mechanism, nevertheless, will function to open the intake of the compressor. For example, if the drop should be ten pounds per square inch,

this would be sufficient to permit diaphragm 43 JI t andasse to engage seat Il. No additional pressure will now be placed in chamber-ll and, therefore, the pressure therein will drop because of bleed passage 41. When the pressure in chamber 3| drops to such a value that the spring can move valve element 2B to open position, the compressor will againI begin to operate and bring the pressure in l the dome and the tank' up to its maximum value at which point the valve mechanismv willv again l 1. In apparatus of the class described, a fluid u to the receiver, pressure-operated valve means compressor provided with an intake port and an exhaust port, a fluid pressure receiver connected to the exhaust port, a iluid pressure-actuated system adapted to be operated by uid pressure from the receiver, a casing having a passage in coml munication with the intake port, a chamber in the casing, a movable valve member in the chamber and adapted to control the passage, a spring for biasing the valve member to open position, conduit means for' connecting the chamber to the receiver, pressure-operated valve means for permitting uid to flow to the chamber when the pressure in the receiver is a predetermined value,y

means forming a relief passage from the chamber,

and valve means independent of the pressure-- operated valve means and operable by fluid pressure from the fluid-actuating system for causing a release of the fluid under pressure in the chaml ated system adapted `to be operated by uid` pressure from the receiver, a casing having a passage in communication with the intake port, a chamber in the casing, a movable valve member in the.

chamber and adapted to control the passage, a spring for biasing the valve member 'to open position, conduit means vfor connecting the chamber to the receiver, pressure-operated valve means for permitting iiuid to flow to the chamber when i the pressure in the receiver is apredetermined value, means forming a relief passage from the chamber, and spring-biased -valve means operable` by iiuid pressure from the fluid pressure-actuated system for controlling said valve means, said valve means being so associated with the relief passage *hat operation thereof by fluid pressure will first open the passage then close it and release of the pressure will permit reopening of the passage and then a closing thereof under the action of the spring.

compressor'provided with an intake port and an exhaust port, a fluid pressure receiver connected to the exhaust port, a uid pressure-actuated system adapted to be operated by fluid pressure` from the receiver, va casing having'a passage in communication with the intake port, a chamber in the casing, a movable valve member in the"v chamber and adapted to control the passage, a

spring for biasing the valve member to open position, conduit means for connecting the chamber for permitting fluid to flow to the chamber when the pressure in the receiver is a predetermined value, and means forming a restricted relief passage through the movable valve member and placing the chamber in constant communication with the portion of the passage in the casing which constantly communicates with the intake when the passage is closed. L

4. In apparatus of the class described, a fluid i compressor provided with an intake port .and van exhaust port, a fluid pressure receiverconnected to the exhaust port,v a casing having a passage in communication with the intake port,

. a chamber in thecasing, a movable valve member in the chamberv and adapted to control the passage, a spring for'bia'sing the valve memberto open position, conduit means for vconnecting the f chamber to the receiver, and pressure-operated valve means for permitting fluid to flow-to the chamber when the pressure in the receiver isa predetermined value, said valve 'means comprising a seat associated with the conduit means, a- I flexible diaphragm and a spring member for blasing the diaphragm against the seat,.and means including, a restricted passage for placing .the chamber in communication with the intake only of the compressor lwhen the valve member is in closed position.

5. In apparatus of the class described, 'a fluid compressorprovided with an intake port land an exhaust port, a fluid pressure receiver" connected to the exhaust port, a casing having a passage in communication with the intake port, a chamber in the casing, a movable valve member in the chamber vand adapted to control the passage, a spring orbiasing the valve member to open position, conduit means for connecting the l chamberto the receiver, pressure-operated valve means for permitting fluid to flow tothe chamber when thepressure in the receiver is a predetervmined value, said valve "means comprisinga seat *associated with the conduitmeans, a flexible `diaphragm and a spring memberI for biasing the diaphragm against the seat, and means for relieving the pressure in the chamber.

6. In apparatus of the class described, a fluid compressor provided ,with an intakev port and an exhaust port, afluid pressure receiver connectedv tothe exhaust'port, a uid pressure-actuated system adapted to be operated by uid pressure from the receiver, a casing structurlaving two communicating aligned boresand a third bore,-means including a portion of one of. the aligned b'ores for forming a passage communicating-with the intake of the compressor, la movable valve member in said'last `named bore for controllingthe passagea spring for biasing the valve vmember to open position, conduit means for placing the third bore in communication with the bore having the movable valve member and at a point to the rear thereof, means for connecting the third bore' with the receiver, valve means associated with the third bore for preventing iluid 3. In apparatus of the class described, a fluid last vnamed valve means and comprising a movable member in the other of the aligned bores.

'7. In apparatus of the class described, a iluid compressor provided with an intake port and an exhaust port,` a iluid pressure receiver connected to the exhaust port, av fluid pressure-actuated system adapted to be operated by uid pressure from the receiver, a casing having a passage in communication with the intake'port, a chamber in the casing, a movable valve member in the chamber and adapted to control the passage, a spring for biasing the valve member to open position, conduit means for connecting the chamber to the receiver, means forming a relief passage from the chamber, valve means for controlling the relief passage and comprising a movable member having a. valve stem carrying spaced valve

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