US1511468A

US1511468A - Rotary compressor

Info

Publication number: US1511468A
Application number: US670898A
Authority: US
Inventors: Hill Ebenezer
Original assignee: Hill Compressor & Pump Co
Current assignee: Hill Compressor & Pump Co
Priority date: 1923-10-26
Filing date: 1923-10-26
Publication date: 1924-10-14
Anticipated expiration: 1941-10-14

Description

Oct. 14 1924. 1,511,468

- E. HILL ROTARY COMPRES S OR Filed Oct. 26, 1923 2 Sheets-Sheet 1 INVENTOR Wig/L,

ATTORNEY Oct. 14 1924. 1,511,468

E. HILL ROTARY COMPRESSOR Filed Oct. 26. 1923 2 Sheets-Sheet 2 INVENTOR M \/M A! TLIORNE Y Patented Oct. 14, 1924.

UNITED STATES I 1,511,468 PATENT OFFICE.

EBENEZER 'HIIJL, OF SOUTH NORWALK, CONNECTICUT, ASSIGNOR TO THE HILL COM- PRESSOR & PUMP COMPANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

ROTARY COMPRESSOR.

Application filed October 26, 1923. Serial No. 670,898.

To all whom it"may concern: 4

Be it known that I, EBENEZER HILL, a citizen of the United States, residing at South 'Norwalk, in the county of F airfield 5 and State of Connecticut, have invented a new and useful Improvement in Rotary Compressors, of which the following is'a specification.

This invention relates to motor driven rotary fluid compressors of the type in which there is a rotor connected with-and driven by the armature shaft of an electric motor, which rotor contains and actuates two intermeshing pumping gears that are held in engagement with a wall of the pumping chamber so that the fluid being pumped will not leak across the faces of the gears, primarily, as on starting, by a light spring, but when in operation, by the excess discharge pressure of the fluid pumped exerted against the back of the rotor. In compressors of this characterwhen there is merely atmospheric pressure on both the intake and discharge sides, the rotor is held against the wall of the pumping chamber by the tension of the spring back of the rotor, with only sufficient force to cause slight frictional engagement, so that the motor starts the comressor easily. As the discharge pressure uilds up under the action of the compressor,

the force on the back of the rotor increases and the sealing engagement of the rotor and gears with the wall of the pumping chamber is correspondingly increased. When the compressor is working the pressure on the opposite sides of the rotor is to an extent balanced there being little more pressure on the back than the front, but this is not excessive and therefore the friction is not great and the motor drives the com pressor easily.

When such a compressor 15 stopped with pressure on the discharge side that pressure as soon as the compressor starts and begins to pump the pressure on the front of the rotor increases to nearly that on the back, and the frictional engagement of the rotor and ears with the wall of the pumping chain er being thusreduced the motor runs with its normal friction load. These factors make necessary the employment of a relatively large sized motor .and one that is especially built so as to have a high starting torque, which will overcome the initial frictional load when the compressor is stopped under pressure.

The object of the present invention is to provide equalizing means vpreferably located on the intake side of the compressor, which will remain inactive when the pressure is atmospheric on both sides, or is practically balanced on both sides of the rotor, as when the compressor is working, but will, if the 75 compressor is stopped with a high pressure on the discharge side, act to retain the pres-' sure on the intake side at substantially the same degree as on the discharge side, in order that the only friction of the rotor 1 and gears against the wall of the pumping chamber will be that due to the'action of; the spring. -.With the pressure thus in effect balanced, the motor will start the compressor easily and without overload. As a' as result of the use of this equalizing means a smaller and less expensive motor, with a standard starting torque, can be used, than is required when the compressor is not provided with equalizing means. This effects a considerable saving in the initial cost of the apparatus and an economy in running expense.

This object is attained by arranging a valve on the intake side of the compressor, desirably in the intake port in the head, in such manner that it offers no practical obstruction to the flow of fluid under the normal operation of the compressor, but when the compressor is stopped with high pressure on the discharge side, and the fluld tends to leak back across the faces of the pumping gears, that leakage will cause the valve to close the intake port and retain the fluid pressure on the intake side or front 105 faces of the rotor and gears substantially the same as on the discharge side or back face of the rotor, thus reducing the friction so that the compressor will again start without excess resistance to torque. The equalizing In the accompanying drawm s Figure 1 shows a side view of a motor riven com- 1 pressor of the character referred to, with a portion of the compressor cut in longitudinal section to disclose anequalizing means arranged in the intake port or the head. Fig. 2 is a transverse section of the compressor on the plane indicated by the dotted hne 22 on Fig. 1. Fig. 3 is a transverse section on the plane indicated by the dotted line 33 on ig. 1.

The casing 1 which is generally circular in outline contains a cylindrical pumping chamber 2 that is closed at one end by a head 3 which is fastened to the casing by any suitable means. The casinghas an intake passage 4 on one side and a discharge passage 5 on the other side, whlle the head has an intake port 6 leading from the intake passage to the pumping chamber and a discharge port 7 leading from the pumping chamber to the discharge passage. Rotatably fitting and having a slight movement axially in the pumping chamber is a rotor 8. The hub 9 of the rotor is mounted on antifriction bearings 10 the inner ring 11 of which is fastened to the hub while the outer race ring 12 is fitted so that it may have a slight axial movement in the casing. The driving shaft 13 is splined in the hub of the rotor so that while the shaft will turn the rotor it will not interfere with the axial movement of the rotor. Fastened in the ro-= tor is an internally toothed gear 1a and engaging the teeth of this gear are the teeth of -an externally toothed gear 15. The externally toothed gear is mounted on anti-friction bearings 16 arranged in a cavity 17 in the gear and supported by a stud 18 fastened in the head. The stud is positioned out of line with the driving shaft so that the axis of the externally toothed gear will be eccentric with the axis of the internally toothed gear. One of these gears has more teeth than the other and they coact in a well known manner to effect the pumping or compression of fluids.

A spring 19 is arranged in a cavity 20 that communicates with the pumping chamber, in such manner that it thrusts against the outer race ring 12 and through the bearing presses the rotor and the faces of the pumping gears against the inner face of the head. Lubricant is introduced into this cavity. Leading from the reservoir 21 into which the fluid is pumped, to the cavity containing the spring is a pipe 22. The function of thisconnection is to admit discharge pressure to the cavity and permit it to be exerted on the back of the rotor. This connection also is adapted to conduct back lubricant which has been forced through the joints of the pump and out through the discharge pipe. A. common type of gland packing 23 is arranged in the end of the casing to prevent leakage from the spring cavity around the driving shaft.

A duct or passage 2 is made throughthe hub of the rotor from the pressure cavity containing the spring back of the rotor, to the cavity containing'the bearing for the externally toothed gear in front of the rotor. When the pump is runnin the centrifugal force of the externally toot ed gear and the fact that it wipes around on the face of the head is sufficient to allow just the right amount of lubricant to work out on the faces of the gears and also between the contacting faces of the teeth. The lubricant which escapes dpasses through the discharge and is returne to the pressure chamber so as to furnish a,v continuous supply of lubricant under pressure. v

In the apparatus illustrated the armature shaft of the electric motor 25 is directly connected with and acts as the driving shaft for the rotor of the compressor. In order to accomplish the object of this invention and enable the motor to start without excessive torque and overload, in the apparatus shown,

a valve 26 is located in the head and is pressed by a light spring 27 so as to normally close the intake port. This valve and spring are located in a screw plug 28 threaded into the head opposite the intake port. The valve however could be placed at any convenient locality on the intake side of the compressor.

When the compressor is started up and as it continues to run, the inrushing fluid to the pumping chamber overcomes the li ht tension of the spring and holds the equa izing valve open. As there are no pulsations in the compressor and the inrush of air is substantially steady the equalizing valve has no vibration. However when the compressor is stopped with fluid pressure on the discharge side, the equalizing valve is closed by its spring because there is no entering fluid to hold it open. Immediately this valve closes the pressure that leaks back across the faces of the gear teeth from the discharge cavities into the intake cavities, as it cannot get past the equalizing valve, it builds up until the pressure on both sides of the rotor becomes equal. With the pressure balanced the only force tending to hold the rotor and gears against the face of the head is that of the spring in the cavity back of the rotor, and this being relatively light the frictional resistance of the rotor and gears to the motor on starting will be the same as if there was atmospheric pressure on both the intake and discharge sides of the compressor. With this arrangement there is an advantage in permitting a slight amount of leakage across the face of the gears. If the compressor is to start up and shortly stop, and then soon start up again, automatical on a fluctuating cycle of pressure which requires it to start and stop quickly at various intervals, the amount of leakage could be increased somewhat, so that the pressure due to the closing of the intake by the equalizing valve would act promptly and the stabalizing of the pressure on the rotor be quickly effected, in order that the motor be in condition to start at any time without excessive over load. v

This pressure equalizing valve in the inlet has another advantageous function. Besides equalizing the pressure and allowing the motor to start without ahigh starting torque, it ensures the same pressure at both ends of the lubricating port through the rotor. This stops the lubricant flow as there is no excess pressure on the back to ,force it through the port on account of the pressure being the same on both sides, and the rotation having ceased, there is no wiping effect of the gears to pass this lubricant along. Therefore in addition to making the starting torque lighter the supply of lubricant is automatically stopped and started with the compressor by the equalizing means.

The invention claimed is 1. A rotary compressor comprising a casing containing a pumping chamber with an intake to and a discharge from said chamber, a rotor rotatable in and having an axial movement in said chamber, intermeshing internal and external pumping gears rotated by and having an axial movement with said rotor, means for conducting discharge pressure to the back of the rotor for forcing the rotor and gears toward the front end of the pumping chamber, and means on the intake side permitting an unrestricted flow of fluid to the front of the pumping chamber but preventing the escape of fluid back from the pumping chamber so as to kee the pressure on the front of the rotor su tantially the same as the discharge pressure on the back of the rotor when the compressor is idle and thereby lower. the starting torque of the compressor.

2. A rotary compressor comprising a casing containing a pumping chamber, a head closing the front end'of the pumping chamber, said head having an intake to and a discharge from said chamber, a rotor rotatable'in and having an axial movement in said chamber toward and from the head, intermeshing internal and external pumping gears rotated b and having an axial movement with sai rotor, means for conducting discharge pressure to the back of the rotor for forcing the rotor and gears toward the head, and means on the intake side permitting an unrestricted flow of fluid to the front of the pumping chamber but preventing the escape of fluid back from the pumping chamber so as to keep the pressure on the front of the rotor substantially chamber, intermeshing internal and external pumping gears rotated by and having arr axial movement with said rotor, a spring in the cavity adapted to force the rotor and gears toward the front of the pumping chamber, means for conducting discharge pressure to the back of the rotor for, with said spring, forcing the rotor and gears toward the front of the pumping chamber, and means on the intake side permitting an unrestricted flow of fluid to the front of the pumpin chamber but preventing the escape of uid back from the pumping chaimber so as to keep the fluid pressure on the front of the rotor substantially the same as the fluid pressure on the back of the rotor when the compressor is idle and thereby lower the starting torque of the compressor.

4. A rotary compressor comprising a casing containing a pumping chamber with an intake to and a discharge from said chamher, a rotor rotatable in and having an axial movement in said chamber, an electric motor directly connected with and adapted to drive the rotor, intermeshing internal and external pumping gears rotated by and having an axia movement with said rotor, means for conducting discharge pressure to the back of the rotor for forcing the rotor and gears toward the front end of the pumping chamber, and means on the intake side permitting an unrestricted flow of fluid to the pumping chamber but preventing the escape of fluid back from the pumping chamber so as to keep the pressure on the front of the rotor substantially the same as on the back of the rotor when the compressor is idle and thereby lower the start- I ing torque of the compressor.

5.- A rotary compressor comprising a casing containing a pumping chamber with an intake to and a discharge from said chamber, intermeshing internal and external pumping gears rotated in and having an axial movement in said chamber, means for conducting discharge pressure to the back of the gears for forcing the gears toward the front end of the pumping chamber, and means on the intake side permitting an unrestricted flow of fluid to the front of the pumping chamber but preventing the eslower the starting torque of the compressor.

6. A rotary compressor comprising a cas ing containing a pumping chamber, a head closing the front end of the pumping chamber, said head having an intake to and a discharge from said chamber, a rotor rotatable in and having an axial movement in said chamber toward and from the head, intermeshing internal and external pumping gears rotated by and having an axial movement with said rotor, means for conducting discharge pressure to the back of the rotor for forcing the rotor and ge rs toward the i head, and a valve in said head on the intake side permittingan unrestricted flow of fluid to the front of the pumping chamber but preventing the escape of fluid back from the pumping chamber so as to keep the pressure on the front of the rotor substantially the same as the discharge pressure on the back of the rotor when the compressor is idle and thereby lower the starting torque of the compressor.

7. A rotary compressor comprising a casing containing a pumping chamber with an intake to and a discharge from said chamber, a rotor rotatable in and having an axial movement in said chamber, intermeshing internal and external umping gears rotated by and having an axial movement with said rotor, a spring adapted to force the rotor and gears toward the front of the pumping chamber, means for conducting discharge pressure to the back of the rotor for, with said spring, forcing the rotor and gears toward the front of the pumping chamber,

and means on the intake side permittin an unrestricted flow of fluid to the front 0 the pumping chamber but preventing the escape of fluid back from the pumping chamber so as to keep the fluid pressure on the front of the rotor substantially the same as the fluid pressure on the back of the rotor when the compressor is idle and thereby lower the starting torque of the compressor.

8. A rotary compressor comprising a casing containing a pumping chamber with an intake to and a discharge from said chamber, a rotor rotatable in and having an axial movement in said chamber, intermeshing internal and external pumping gears rotated by and having an axial movement with said rotor, said gears being located on the front take side permitting an unrestricted flow of v fluid to the pumping chamber but preventng the escape of fluid back from the pumpmg chamber so as to keep the pressure on the front for. the rotor substantially the same as on the back of the rotor when the compressor is idle and thereby lower the starting torque of the compressor.

9. A rotary compressor comprising a casng containing a umping chamber with an lntake to and a ischarge from said chamber, intermeshing internal and external pumping gears rotated in and having an axial movement in said chamber, means for applying spring pressure and discharge pressure to the back of the gears for forcing the gears toward the front end of the pumping chamber, and means on the intake side permitting an unrestricted flow of fluid to the front of the pumping chamber but preventing the escape of fluid back from the pumping chamber so as to keep the fluid pressure on the front of the gears substantially the same as the discharge pressure on the back of the gears when the compressor is idle and thereby lower the starting torque of the compressor.

10. A rotary compressor comprising acasing containing a pumping chamber with an intake to and a discharge from said chamber and a cavity communicating with the back of said chamber, a rotor rotatable in and having an axial movement in said chamber, said rotor having a passage from'back to front, intermeshing internal and external pumping gears rotated by and having an axial movement with said rotor, a spring in said cavity adapted to force the rotor and gears toward the front of the pumping chamber, means for conducting discharge pressure to the back of the rotor for, with said spring, forcing the rotor and gears toward the front of the pumping chamber, and means on the'intake side permitting an unrestricted flow of fluid to the front of the pumping chamber but preventing the escape of fluid back from the pumping chamber so as to keep the fluid pressure on the front of the rotor substantially the same as the fluid pressure on the back of the rotor when the compressor is idle and thereby lower the starting torque of the compressor.

EBENEZER HILL.