US2234488A

US2234488A - Compressor unloading valve mechanism

Info

Publication number: US2234488A
Application number: US303378A
Authority: US
Inventors: Dick Burns
Original assignee: Wagner Electric Corp
Current assignee: Wagner Electric Corp
Priority date: 1939-11-08
Filing date: 1939-11-08
Publication date: 1941-03-11
Anticipated expiration: 1958-03-11

Description

March 11, 1941; Y mcK 2,234,488 pou'rnzssoannmnpme VALVE uscmmxsu- Filed Nov. is, 1939 3 -2 Sheets-Sheet x INVENTOR.

ATTORNEY B. DICK connissson' momma VALVE uscmrsu Filed Nov. 8, 19:59 2 Sh eets-Sheet 2- INVENTOR RNS DICK rronamzwr PatentedMar, 11, 1941 Burns Dick, Ferguson, Ma,

Electric Corporation, tion of Delaware assignor to Warner St. Louis, Mo., a corpora- Application November 8, 1939, Serial No. 303,378

5 Claims. My invention relates to compressors and more particularly to valve mechanism for unloading the compressor under certain conditions.

One of the objects of my invention is to pro- 5 vide an improved valve mechanism for automatically unloading a compressor when the fluid compressed thereby and discharged into a receiver is a predetermined value.

Another and more specific object of my in- 1 vention is to embody electrical-operated control means in the compressor unloading valve mechanism to thereby facilitate the installation of .the control valves which form a part of the' r mechanism and also lower the cost of manufacture.

Other objects of my invention will become apparent from the following description taken in connection with the accompanying drawings in which Figure 1 is a view, partly in section, of a compressor having associated therewith an unloading valve mechanism embodying my invention and Figure 2 is a view, partly in section, showing a modified unloading valve mechanism.

Referring to the drawings in detail, the rotary compressor is of known construction and comprises a stator i having eccentrically mounted therein a rotor 2 secured to a drive shaft 3 jour naled in the end plates 4 and-5. The rotor 2 is provided with a plurality of spaced slots extending in an axial'direction in which are mounted reciprocable blades I (one only being shown) biased outwardly into engagement with the inner surtace'of the stator by springs 8. The end plate 41s provided with an intake passage 9 and the end plate with an outlet passage i0. Secured to the end plate 5 is anoil reservoir or dome II which contains oil for the purpose of lubricating the compressor. In the construction shown the shaft '3 of the compressondrives an oil p mpJl to pump oil from the through'passagefl and discharge it I4 through the opening II. The oil is free toin the well the compressed air. The discharge port l0 has asociated therewith a check valve 20 for preventing any of the compressed air from returning to the compressor. The oil dome communicates with the compressed air receiver or tank 2! by a conduit 22 and a check valve 23 prevents return of compressed air to the dome. The compressed air may be used for any purpose desired,

as for example, the actuation of vehicle brakes.

In the type 01' compressor just described the compressor is generally automatically unloaded by shutting oil the intake when the receiver tor the compressed air discharged by the compressor reaches a predetermined value and again allowed to compress air when the compressed air in the receiver falls to a given pressure below the pre-' determined va1ue., With such an arrangement, d that when the compressor it has been discovere is unloaded an excess amount of oil may be fed to the compressor and cause it to become choked" because oi the compressed air acting upon the oil and forcing it into the compressor. It has also been discovered that the shutting off of the compressor by closing the intake does 'not cause the compressor to run idle .since the compressor still operates to compress the air remaining in the compressor which may be partially discharged into the oil dome against the compressed air already therein or, if this is not accomplished due to insuihcient air to com; press, recirculated and recompressed continuously. By the compressor being partially under load and performing work, it will continue to generate heat and use power, notwithstanding no additional compressed air is being added to the receiver All of these undesirable operating tea.-

tures present when the compressor intake is shut hody of oil into a well flow through the passage IS in. shaft 3 and then into. the compressor by way of the} keyway ll to thus provide lubrication for the movable parts of the compressor. Inorder that the oil may be forced into the compressor under pressure during operation of the compressor, the

' body of-oil in theoil dome is caused to be sub- 50 iect to the fluid under" pressure discharged from the compressor. is accomplished by having the discharge port i| connec which extends above the oil rator l4 removes any excess discharged from the compres line. An oil sepaoil which may be sor together with ted to a pipe ll oil can be eliminated to a large. extent by also unloadingthe oil'dome at the same time the intake is shut oil. With the air in the oil dome under atmospheric pressure, the oil forced into the compressor will be'reduced and the air and oil being circulated in the compressor will be free to be discharged into the oil dome against atmospheric pressure instead of against com-" Pressed air.- A superior operating compressor results which will require less power to operate when no air isrequired to be compressedQ Also the compressor will operate at a much cooler temperature, less oil willbe used, and the life of the compressor extended. My improved valve mechanism for shutting off the intake and opening the oil reservoir to atmosphere coinprlsesa casing 24' provide with intercommunicating passages 25 and- 2 the former being connected to the inlet passage 9 and the latter to the atmosphere through the 'air cleaner 21. Associated with passage 29 is a valve seat 29 and cooperating therewith is a valve member 29 positioned in an enlarged chamber 39 between the

passages

25 and 29. The valve member 29 is normally biased to an open position by a light spring 3|.

The casing of the valve mechanism is also provided with a chamber 32 which is connected to the top of the oil reservoir or dome II by a conduit 33. The chamber 32 communicates with passage 29 by means of a passage 34 which has associated with its end a valve seat 39 and cooperating with this seat is a valve element 39 positioned in chamber 32 and normally held upon the seat by spring 31. Between the chamber 32 and the passage 25 is a bore 39 in which is guided an extension 39 carried by the valve member 29. g The extension is of such length that when the valve member 29 is in open position, the valve member 39 will be held seated by its spring and when the valve member 29 is moved to closed position, the extension 39 will force the valve member off its seat and place chamber 32 (and also the oil reservoir II) in communication with atmosphere through passage 34.

In order that the valve member 29 may be moved to closedposition and the valve member 39 to open posit on when the pressure in the receiver 2| is a predetermined value-there is provided a solenoid 49, the winding 4| of which is connected to the valve member 29. One-end of the winding is connected to ground by a conductor 43 and the other end is connected by a conductor 44 to one side of the battery 49, the other side being connected to ground by conductors 49 and 41 through a pressure-operated switch 49. This switch comprises a fixed contact 49 connected tothe conductor 41 and a movable contact 59 connected to the conductor 49. The movable contact is carried on a diaphragm 9| which is biased by a spring 52 to a position where the contacts 49 and 99 will be normally disengaged. The diaphragm 9| forms with the housing 93 of the switch, a chamber 54 which is in constant communication with the compressed fluid in the receiver 2| by a conduit 99. Spring 92 for the switch is of such strength that it will maintain the contacts separated untila predetermined pressure-is present in the receiver of the chamber. 94." Ibrr the purpose of this description, this pressure is considered as one hundred pounds per square inch.

When the compressor is operating, the parts of the valve mechanism and the switch are in the position shown in Figure 1. Under these conditions the valve element 29 will. be open and the valve member 39 will be closed. This will permit air to oe drawn into the compressor where it is compressed and forced out through the check valve 29 into the oil reservoir II and then through the check valve 23 into the receiver' 2|. when the compressor has operated 65 sumciently to bring the pressure in the receiver to the assumed predetermined'value of one hundred pounds per square inch, the contacts 49 and 99 of the switch will be closed by movement of the diaphragm against the action'of springv 92.

Closing of the switch will energize the solenoid 49 and cause its armature to move the valve member 23 to theleft, thereby shutting oi! the intake e to the compressor. Simultaneously with (the movement of the valve member 29 to closed 7 position, the valve member 39 willbe moved of! 'outlet valve 29 off its seat against any built-up its seat and thereby place the oil reservoir in communication with .atmosphere and cause the pressure in the reservoir to drop to atmospheric pressure. The compressor now-' will be substantially completely unloaded. Any air which may 6 be in the compressor will be easily forced out through the check valve 29 into the oil dome and from there into atmosphere since it is not necessary for the air being compressed to move the pressure. There may be a slight leakage of air in the compressor around the extension 39 but this air will be easily circulated through the compressor forced out through the outlet valve with very little compressing operation. The connecting of the oil reservoir to atmosphere also results in placing the oil in the oil well i4 under atmospheric pressure and the only oil which will flow into the compressor will be that which flows'under the action of gravity and that which is pulled 20 in as a result of sub-atmospheric pressure in portions of the compressor. The flow of oil will be so decreased that the compressor will not tend to choke" up as would be the case if the intake were shut oflf and the pressure in the oil dome 25 not relieved. Since the compressor is now running idle and not performing any compressing operation, the power necessary to turn the rotor k is a minimum and the heat being generated by the compressor is also a minimum. Consequently, an

the compressor will have an opportunity to cool as will also the oil in the reservoir. The result is a more emciently operating compressor and one in which the life is considerably extended When fluid under pressure is used ,irom the- 35 air receiver and the pressure therein drops to' such a value that spring 52 of the switch can open the contacts thereof, the solenoid will be. de-energized and 'the valve member 29 moved to an open position by spring 39. Simultaneously with the opening of the valve member 29, the valve member '39 will be closed, thereby again sealing the oil reservoir. The compressor can now begin to compress air and again force it into the air receiver to thereby bring the pressure of 5 the air in the receiver up to the predetermined 1 value of one hundred pounds per square inch.

In Figure 2 there is shown a modified valve mechanism for shutting off the intake of the compressor and venting the oil'reservoirto at- 50' mosphere. In theflgure the parts similar to those disclosed in Figure 1 have the same referby a spring 93, the tension ofwhich is adjustable by the nut 94. The valve member 92 is provided. with an extension 99 which is guided in a sleeve 95 99 carried by a member 91 of insulating material. The extension 99 abuts against a diaphragm 99 which is held in sealed engagement with the valve casing by a cap 99. The chamber 19 above the diaphragm is placed in communication with the 7 airreceiver by a conduit II.

The oil dome II is provided with a vent passage I2 which is connected to atmosphere through the air cleaner by a conduit I3. Associated with the vent passage is a valve seat 14 ll 15 ductor 82.

, 62 will not be moved to closed 25 hundred pounds per square inch pressure is present in the air receiver and also chamber above 50 thereby sealing the oil 65 trolling bot and cooperating therewith is a valve member '15 having connected with its stem a plunger I6 5 to hold the valve member seated. One end of the winding 19 of the solenoid is grounded and the other end is connected bya conductor 80 through a battery ill to the valve member 82 which is made of conductingmaterial and forms 10 one of the contacts of a switch. The other contact for this switch is the valve seat 6| formed on the valve casing which is also made-oi conducting material. The circuit is completed by connecting the valve casing to ground-by a con- In order that the valve 62 may be completely insulated in the valve casi an insulating member 83 is interposed between the spring I3 and the valve element. As already mentioned, the guide sleeve 66 is insulated from 20 the casing by the member 61.

'When the compressor is operating, the parts are in the position shown in Figure 2. The tension of spring 53 is such that the valve member position until one the diaphragm. When the air receiver reaches the pressure of one hundred pounds per square inch, the valve member 62 will be moved to closed position and shut ofi the intake of the compressor. The suction of the compressor ;will now be eflective to assist the holding'of the valve member on its seat. As the valve member 62 engages-the seat, theelectrical circuit is closed.

The closing of the switch energizes the solenoid l1 and causes the plunger 18 to move the valve member 15 oil its seat, thereby placing the oil reservoir in communication with the atmosphere and dropping the pressure therein. The

compressor will then be substantially completely unloaded.

When compressed air in the receiver is used and the pressure therein drops to such a value that the spring 83 can again open the valve member 62 against the Iorces tending to hold it closed,

the compressor will again begin to operate to compress air. As the valve member 62 is unseated, the electrical circuitwill be broken and.

the valve member 15 closed by the spring 18, reservoir and resulting in the compressed air discharged therein flowing directly to the air receiver.

By employing electrical means for controlling I either one or both of the valves of. the unloading 5 valve mechanism, installation thereof is facilitated. In the construction shown in Figure 1, the switch can be placed in any convenient place and no problem is employed in connecting the switch in circuit with the solenoid. In 'the con- 5 struction shown in Figure 2, the valve for vent-,

ing the oil reservoir can be made separate from the intake shutit valve and mounted at-a distance therei'rom directly on the reservoir casing, A single fluidmotor can .be employed for. conlg valves, thus minimizing the cost. Being aw re oi the possibility of other modi'- flcations'in the particular'structures herein described without departing from the fundamental principles oi my invention, I do not intend that their scope be limited except as' set forth by*the 1 appended claims.

Having fully described my invention, what I claim as new and desire to secure by letters Patent oithe United States is:

- placing the discharge port in communication with for placing the discharge 'with the atmosphere, at the intake-valve when and a movable valve- 1. In compressed air storage apparatus comprising a receiver and an air compressor 'provided with intake and discharge ports, a normally open intake valve, a normally closed valve for placing the discharge portin communication with the atmosphere, and automatically operable means for closing the intake valve and substantially, simultaneously opening the second named valve whenthe fluid pressure in the receiver reaches a predetermined value, said means comprising a solenoid for controlling at least one of said valves, the solenoid, and a switch: caused to be closed when the pressure in the receiver reaches said predetermined value. g

2. In compressed air storage apparatus comprising a receiver and an air compressor provided with intake and discharge ports, a normally open intake valve, a normally closed valve for an electrical circuit for the atmosphere, means for operatively connecting the valves together so that named valve isclosed the second named valve will be open, a solenoid for controlling said valves, an electrical circuit including a switch for cans-- ing operation of the solenoid, and means for. closing the switch when the pressure in the receiver is a predetermined value. 3. In compressed air storage apparatus comprising a receiver and an air compressor provided with intake and discharge ports, an intake valve resiliently biased to an open position, a second valve resiliently biased to closed position and capable of connecting the discharge port to atmosphere, the movable elements of said valves being in axial alignment, a rod operatively connecting the movable valve elements, a solenoid for closing th intake valve and by means oi the rod cause the second valve to be open, and' when the first an electrical circuit for energizing the solenoid 40 including a normally open switch, .and a fluid motor connected to close the switch when the receiver pressure reaches a predetermined value.

4. In compressed air storage apparatus comprising a receiver and vided with intake and discharge ports, a normally open intake valve,

a normally closed valve port in communication fluid motor for closing ceiver reaches apredetermined value, a solenoid J for opening the second named valve, and an electrical circuit including a switch for energizing the solenoid, said switch being so associated with the fluid motor that it position by the fluid motor simultaneously with the closing of the first named valve. 5. In compressed air storage apparatus comprising-a receiver andan air compressor providan air compressor pro- 45' the pressure in the re-l will be moved to closed ed with intake and discharge ports, anormally open intake valve, said valve comprising a seat element made of electrical conductive materialfla normally closed valve' for placing the discharge port in communication with the atmosphere, a intake valve by seating the movable'valve element when the pressure in the receiver reaches a predeterminedvalue, va solenoid for opening the second named valve and an electrical circuit for seat and the movable valve element as a switch.

BURNS DICK.

fluid motor tor closing the energizing the solenoid and including the valve 7