US2455297A - Sliding vane air pump lubrication - Google Patents

Description

Nov. 30, 1948.

Filed Feb. 13, 1943 w. H. cuR-Tls E1'` AL 2,455,297 SLIDINGANE AIR PUMP LUBRICATIN l 2 Sheets-Sheet 1 1 Nov. 30, v1948. w. H. CURTIS ETAL 2,455,297

SLIDING VANE AIR PUMP LUBRICATIOVV Filed Feb. 13, 1943 2 Sheets-Sheet 2 we y l @asa-7.1. l@ MEV/5.

Patented Nov. 30, 1948 SLIDING VAN E AIR PUMP LUBRICATION WilliamH. Curtis, Los Angeles, Calif., and Russell R. Curtis, Dayton, Ohio, assignors, by mesne assignments. to

Thompson Products, Inc.,

Cleveland, Ohio, a corporation of Ohio Application February 13, 1943,v Serial No. 475,700

This invention relates to a pump adapted to compress a uid such as air to the nal desired pressure and then discharge the fluid at this pressure.

Specifically thisinvention relates to a vanetype air pump capable of producing higher. pressures than heretofore developed by vane pumps.

The pumps of this invention include a varied rotor having a hollow central chamber adapted for receiving oil to act on the inner ends of the vanes and urge the same outwardly against the wall of the pump bore.

A feature of the invention includes the bleeding of some of the oil from the rotor chamber to the pump bore for lubricating the bore. The oil is introduced at a point in the bore where it will not flow back to the inlet side of the pump.

A further feature of the invention resides in applying high oil pressure to the inner ends of the vanes as they pass across the discharge side of the pump and a lower oil pressure to the inner ends of the vanes as they pass across the inlet and pumping portions of the pump.

The invention includes a pump assembly wherein compresesd air together with entrained oil from the pump is fed through an oil separator so that the oil will be filtered from the air. The oil is then cooled to remove heat of compression and the cooled oil is fed back to a chamber in the rotor of the pump. The air, freed of oil in the oil separator, can be delivered to a storage tank. The oil delivered to the rotor chamber is under pump discharge pressure and has an amount of air dissolved therein depending upon this discharge pressure. tor chamber is bled to the pumping chamber to lubricate the chamber. This' point in the pumping chamber at which the oil is introduced must be at lower pressure than the discharge pressure of the pump, in order that oil will ow to the chamber. Thus the oil must be subjected to a pressure drop which liberates air in solution in the oil and the amount of air liberated will increase as the pressure drop increases.

According to this invention the pressure drop is regulated to maintain proper circulation oi oil without undue liberation of air from the oil. Thus theoil is introduced into the pumping chamber at a point where air is under partial but not full compression, in other words, at a point spaced from the pump inlet and outlet sealed by vanes from the inlet and outlet. As a result of this arrangement, the work of recirculating air freed from solution in the oil is minimized and the pump will have greater emciency.

y l claims. (ci. 23o-207) It is an object of this invention to provide a rotary vane-type pump capable of discharging compressible iiuids such as air underhigher pressures than have heretofore been obtained through the use of vane-type pumps.

Another object of the invention is to provide a high pressure pump assembly that can be operated without the use of check valves.

A further object of the invention is to provide a vane-type pump which will deliver compressible uids such as air at the nal desired discharge pressure at a constant rate, thereby eliminating the heretofore-encountered pressure surges.

A still further object of the invention is to provide a pump assembly which circulates oil at a, controlled pressure drop for lubricating the.

assembly without delivering this oil along with the uid being pumped.

A still further object of the invention is'to provide a high pressure air pump assembly with an oilA circulation system for lubricating the pump parts without liberating any more air dissolved in the oil than is necessary for oil circulation.

A further object of the invention is to provide a vane-type pump having an oil-circulating attachment effective for urging the .pump vanes against the bore of the pump housing.

A still further object of the invention is to provide a pump assembly of the rotary vane type wherein the vanes are urged outwardly from the rotor at pressures controlled by the pump discharge pressures.

A further object of the invention is to provide a pump asesmbly with a recirculating lubricating system wherein heat of compression is absorbed by the lubricant and then liberated externally of the pump.

Other and further objects of the invention will be apparent to those skilled in the art from the following detailed description of the annexed sheets of drawings which, by way of preferred example only, illustrate one embodiment of the invention.

On the drawings:

Figure 1 is a vertical cross-sectional, somewhat diagrammatic view, with parts in elevation, of a pump assembly according to this invention.

Figure 2 is another transverse cross-sectional view of the pump shown in Figure 1.

Figure 3 is an axial cross-sectional view, with parts in elevation, taken substantially along the line III-III of Figure 2.

As shown on the drawings:

As shown in Figure 1, the pump l0 has an air inlet lI, and a discharge outlet I2 connected through a pipe or tube I3 with the upper end of a filter I4. The lter I4 is a tank or box having a plurality of spaced parallel screens I5 through which air must pass before it reaches the outlet tube or pipe I6 leading to a storage tank I1. As will be hereinafter more fully described, oil is pumped by thepump I along with the air and this oil is ltered out of the air by the screens or other lter media I in the filter device I4. The oil is collected at the bottom of the device I4 and flows through a tube or pipe I8 which is coiled as at I9 back to the pump I0. A ian driven by a motor 2| is provided adiacent the coiled portion I9 of the tube I'8 for cooling the oil before it is returned to the pump. The oil will absorb heat of compression in the pump and thiscooling arrangement Iwill remove the heat of compression from the oil externally of the pump.

As best shown in Figure 3 the pump Ill includes a block or base 22 providing a plain bearing 23 for a shaft 24. The shaft 24 can be driven by the same motor 2i driving the fan 20, or can be driven by a different prime mover. A ring' 25 having an interior wall 26 providing the pump bore is clamped between the block 22 and an end cap 21 by 'means of bolts 28 which extend through the end cap and ring and are threaded into the block 22.

A rotor 29 is secured on the shaft 24 in the ring to be driven by the shaft. This rotor 29 has a central bore 30 therethrough.

As best shown in Figures 1 and 2, the rotor 29 has radial slots 3l extending from the bore 6 30 to the outer periphery of the rotor. These slots 3I each receive a vane 32 of the blade type.

The vanes 32 have outer ends 32a slidable on the inner wall 26 of the ring 25 and have inner ends 32h which are always held in the slots 3I by the wall 26.

It is preferred to have the pump equipped with a large number of vanes 32 and twelve such vanes are shown. The large number of vanes makes it possible to more eiliciently trap, in the pumping portion of the pump, airwhich is received from the inlet II so as to provide segregated chambers of air undervslightly increasing pressures to reduce the tendency of leakage from one chamber to another and to minimize pulsations in discharge pressures.

The ring 25 is cored out as shown in Figure 2 to provide the inlet u and the outlet lz, and

blind bore 36 therein communicating through radial holes 31 with a localized channel 38 in the bore 30 provided between two ribs 39 on the pin as best shown in Figures l and 2. Oil from the tube I8 will thus flow into the blind bore 36 of .the pin 35 and through the holes 31 into the localized chamber portion 38. The pin 35 has a recessed portion 40 extending around the periphery thereof to the ribs 39 thus providing a second and larger localized chamber 4I in the bore 30.

The pin 35 is slightly smaller than the bore 30 so that the ribs 39 will be spaced from the bore 30. Oil introduced into the localized chamber 4 38 can thus bleed over the ribs 39 into the' localized chamber 4I.

As best shown in Figure 3 the localized chamber 4I communicates with a radial hole 42 in the cap 21. This hole 42 is plugged by means of a first plug 43 and a second plug 43a spaced therefrom. The end cap has axial holes 44 and 45 communicating with the hole 42. The hole 44 communicates with the inner portion of the hole 42 in direct communication with the chamber 4| while the hole 45 communicates with the portion of the hole 42 between vthe plugs 43 and 43a.

A tube 46 is connected through fittings 41 and 48 with the holes 44 and 45 and has a restricted intermediate portion 46a to meter oil from 'the n hole 44 to the hole 45.

The ring 25 and the end cap 21 have another hole 49 therethrough communicating with the hole 45 of the end cap. This hole 49 is connected through holes 50 with the interior wall 26 of the ring 25 at a point spaced from the inlet II and outlet I2 so that oil will be metered into the pump bore at a portion thereof that is sealed by vanes from rthe inlet and outlet and under a pressure less than the outlet pressure, thereby providing "a pressure drop to maintain circulation of oil. Some air, of course, is dissolved by the oi'l, and the amount of dissolved air depends upon the air pressure. As the pressure drops, air will be liberated from the oil. In order to minimize work loss due 'to liberation of dissolved air from the oil because of the pressure drop, the holes 50 communicate with a pumping chamber' zone that is under pressure. As a result, the pressure drop is less, less dissolved air is eliminated, and less air goes back into solution, thereby minimizing work loss of recirculating the air freed from solution in the oil.

By providing a large number of vanes it is possible to successvely'trap off a large number of increments of air between the inlet II and the discharge outlet I2 in the bore 26. Each thus trapped increment will be successively compressed as the Aspace between the bore 26 and the rotor 29 is dccreased. As shown in Figures l and 2. and as is customary in rotary vane type pumps, the rotor is eccentrically mounted in the bore. Each trapped increment of air will then only be at slightly different pressure than the immediately `preceding or immediately succeeding increment. Thus the tendency for blow back from a high pressure zone to a low pressure zone is, of course, minimized. As illustrated in Figure 1, for example, air at atmospheric pressure from the inlet II Awill be received into spaces in the bore 26 between the vanes 32. As soon as a vane 32 passes the inlet II, the air between it and the vane immediately in advance thereof is trapped. Then as the trapped air is advanced by the vanes to be compressed in the decreasingly sized space -between the rotor and bore it will be backed up by another trapped chamber of air at a sliightly lower pressure. By the time the air reaches the discharge outlet I2 it has been cornpressed to its final desired discharge pressure and is immediately vented to the discharge opening I2 from which it will be forced into the filter I4. No blow back will occur at the discharge outlet because the next succeeding increment of trapped air will only be at a slightly lower pressure than the discharge pressure.

By providing 'a large number of trapped increments of air, the discharge pressure is constant and free from surges such as would occur if only a few chambers of air were provided and if the air was vented to the discharge outlet before it had been compressed in a trapped chamber to its final desired pressure. An important feature of the pump of this invention' thus is the provision of a large number of chambers for trapping air during the pumping operation and the compression of the air in each chamber to its final desired pressure before releasing it from the pump.

In operation of the pump, the tube l8.is filled with oil and, if desired, an excess of oil may be allowed to co'ver the bottom of then filter I4. When the pump is operated air will be forced into the filter I4 and will circulate the oil through the tube I8 to the blind bore 36 of the pin 35. Oil under pressure in the bore 36 will flow through the holes 31 into the localized chamber 38. This localized chamber v38 is so positioned in the bore of the rotor 29 that it communicates with the inner ends 32h of the vanes 32 as they are passing 'the discharge outlet I2. Therefore, these particular vanes will be urged outwardly against the bore 26 of the pump with the same pressure tending toforce the outer ends 32a thereof inwardly. viz., the pump discharge pressure. The oil is thus effective to prevent inward lmovement of the vanes because of pressure exerted on their outer edges. l

Now since the pin 35 is of slightly smaller diameter than the bore 30 of the rotor, some of the oil in the localized chamber 38 can bleed over the ribs 39 of the pininto the larger localized chamber BI which is at a lower pressure than the chamber 38. Oil in' this chamber 4I, of

course, communicates with the inner ends 32h of all of the vanes except those passing across the discharge outlet I2. These vanes will therefore also be urged outwardly against the bore 26 of the pump but with less force than when they pass over the outlet.

Some of the oil in the localized chamber 4l will be metered by the restricted portion .46a of the tube 66 into the pump bore 26 ata point sealed oi from the inlet Il by at least one vane 32. The wall or bore 26 of the pump is thus lubricated.

Any oil leaving the pump, such as the oil intro- Jill duced into the bore 26 or the oil leaking from the rotor bore 30 alongside of the vanes 32, is owed with the compressed air into thefllter I4 and the screens or other filter devices I5 in this filter I4 will separate out the oil from the air and return it to the tube I8. The filtered air is then delivered to a storage tank such as Il. No check valves are necessary in the entire system and a constant pressure will be maintained.

It will, of course, be understood that various ,details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not

the purpose to limit the patent granted hereonv otherwise than necessitated by the scope of the appended claims.

We claim as our invention:

1. A pump construction comprising a housing defining a pump chamber having an inlet and an outlet, a slotted rotor rotatably mounted in said chamber in eccentric relation therewith, said rotor having a central passageway communicating with the slots, vanes slidably mounted in said slots having inner ends exposed to said passageway and outer endsriding on the wall of said pumping chamber, a metering pin in said passageway defining an oil chamber directly communicating with the inner ends of only the vanes -passageway joining the thatl are exposed to the outlet and dening a second oil chamber having restricted communication with said first oil chamber and directly communicating with the inner ends of the vanes not exposed to. the outlet, and conduit means connecting said second oil chamber to a portion of said pump chamber at a pressure intermediate that of said inlet and outlet.

2. A pump construction of the rotary vane type including a housing forming a pumping chamber with an inlet and an outlet, a rotor in said chamber having vane slots and a central passageway-communicating with the vane slots, a metering pin fixedly mounted in said passageway, means for supplying oil at the discharge pressure of the pump to said metering pin, said metering pin being'recessed and cooperating with the rotor to define a localized chamber in said passageway communicating directly with the vane slots as they pass across the outlet, and said metering pin having a second recessed portion in the rotor to cooperate therewith to define a second localized chamber in said passageway having restricted communication with said first mentioned localized chamber for receiving meteredv quantities of oil therefrom for feeding said oilpto all of the other vane slots in the rotorat lower pressures than the oil fed to the vane slots as they pass across the outlet.l

3. A rotary vane type pump comprising a-housing defining a pumping chamber having an inlet and an outlet, a rotor rotatably mounted in said chamber in eccentric relation therewith, said rotor having vane slots therein, pump vanes slidably mounted in said slots, said rotor having a central passageway therein-communicating with each of said slots, conduits connecting the outlet of said pumping chamber with said passageway and carrying lubricant under pressure to said passageway, and a lubricant-metering device extending from said rotor connecting said passageway only with that portion of the pumping chamber sealed from the inlet and outlet by said vanes and maintained at a pressure intermediate the inlet and outlet pressure.

4. A pump assembly comprising a rotary vane type pump having a pumping chamber with an inlet and an outlet in angularly spaced relation, a rotor rotatably mounted in said chamber and havingspaced slots therearound extending inwardly from the periphery thereof lengthwise of the rotor, -vanes slidably mounted in said slots and cooperating with the wall of the chamber to define a space sealed' from the inlet and outlet, said space during operation of the pump being at a pressure greater than the inlet pressure and less than the outlet pressure, lubricant-conveying means extending through the axis of said rotor and having communication with the inner ends of said vanes, means joining the pump outlet with said lubricant-conveying means, and a metering lubricant-conveying means with said sealed space in the pump chamber for lubricating the chamber wall without subjecting the lubricant to a high pressure drop.

5. A pump assembly comprising ya housing defining a pumping chamber, a slotted rotor rotatably mounted in said chamber in eccentric relation therewith, vanes slidable in the rotor slots acting against the wall of the pumping chamber, said pumping chamber having an inlet and an outlet, said rotor having a central apertured portion, means in said central apertured portion of the rotor coacting therewith to form a Iirst chamber communicating directly with the inner ends of the .vanes asthey pass the outlet of the pumping chamber together with a second chamber.'4

communicating directlyvwith the innery endsy of the .vanes spaced from the outlet of the pumping` chamber, and a metering passage between said rst and second chambers, an oil reservoir exposed to pump outlet pressure, a conduit connecting said reservoir with said means in the central apertured portion of the rotor lfor feeding lubricant direct to said first chamber to act on the inner ends of the vanes exposed to the pump outiet at full outlet pressure of the pump and to pass through said metering passageway with a pressure drop into said second chamber I REFERENCES CITED The following references are of record in the iile of this patent:

Number Number UNITED STATESPATENTS Name Date Jackson Sept. 14, 1920 Jackson Sept. 14, 1920 Parkyn Dec. 22, 1925 Thomson Dec. 11, 1928 rCuthbert Oct. 15, 1929 Dennedy Jan. 24, 1933 Ogilvie Apr. 3, 19344 Lipman July 17, 1934 lHuff Aug. 11, 1936 Taglio Feb. 13, 1940 Kraissl Mar. 10, 1942 FOREIGN PATENTS Country Date Great Britain Nov. 3, 1910 Switzerland June 1, 1932 Great Britain Aug. 27, 1931

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