US2411606A - Power transmission pump - Google Patents

Description

Nov. 26, 1946. .5. 4. WILSON POWER TRANSMISSION PUMP 2 Sheets-Sheet 1 Filed Sept. :5, 1942 INVENTOR.

BURTON J. WlLSON ATTORNEY.

Nov. 26, 1946. B, wLsoN 2,411,606

POWER TRANSMISSION PUMP Filed Sept. 3, 1942 2 Sheets-Sheet 2 v24 7 72 /IIIIIIA INVENTOR.

Patented Nov. 26, 1946 I I I UNITED STATES PATENT OFFICE}.

Burton vJ. Wilson,- Detroit, Mich., assignor to Vickers Incorporated, Detroit, Mich., a corporation of Michigan Application September 3, 1942, Serial No. 457,163

' 6 Claims. (Cl. 103-435) l 1 v This invention relates to power transmissions, Figure 7 is a cross section on line 1-1 of Figparticularly to those of the type com-prising two ure v g or more fluid pressure energy translating de- Figure 8 1s a cross section on line 8-8 of Figvices, one of which may function as a pump and ure anoth r a fluid m t 5 Figure 9 is a circuit diagram of the pump unit The invention is more particularly concerned f q u with a pumping unit of the rotary, type and with Referring now to Figure 1 there is shown a, control means for regulating the volumetric dismam y h ngtwo cylindrical recesses l2 charge-memos and H in whichare mounted rotary pumping A form of pump in common use in the hydraulic m and The latter -2 be of y Sultpower transmission field utilizes a rotor having able typ n as hown re similar to the vane r described in the patent to Harry F. Vickers, a plurality of substantially radial vanes rotatable D therewith .and slida'ble relative thereto. The 1,989,900- end cap s unted on the I t Stato member body I!) to retain the pump unit [8 inthe recess f figg gg l g igg gs i g z g i lhambers 15 I4 and carries a bearing 22 in which one end of shaft 24 is rotatably mounted. An end cap 28 through which the vanes pass carrying fluid from the inlet port to the outlet pom Single and and filler block 28 retain the pump umt l6 in the recess It, the en cap carrying a bearing 38 ihait is an t t 1 I ur ose I g g z ggg gg fisz ggg 223; 3 5 a pump units. A suitable mounting flange 38 is and m W of WW arthritis: harassing? mg the pump to permit it to circulate fluid idly. 25 port suitable cap screws or other fastening It is object of present g to g; means, not shown, are provided for holding the vide an improved pumping uni w 10 may 7 end plates at 2, 26 and 36 together.

unloaded without requiring an external bypass The, um unit '6 is rovid-ed with two from the discharge port to the suction port of the metricagly cgposite denvegy ports 38 and 40 (See pump Figure 5) and two diametrically opposite suction A further 9 is i i a this ports 42 and 44. The body it is provided with a character wherein the radial movement of the cored passage 5 which has arcuate branches 8 vanes mauve the TOW may be VaYFabIY and so extending partially around the shaft 24150 trolled thereby reguiate the pumpmg ac'tlon connect with the delivery ports 38 and 40. The

either inhibiting it altogether or causing it to passage 45 forms a delivery conduit for the pump take Place in normal n unit' l6 and extends to one sideJetoward the top Further obJects and advantages of the present in Figure 1) of the pumping h invention will be apparentir'om the following de- The suction ports 42 and 44 f the pump unit P reference being 170 the accompany" l6 communicate with a cored passage 58 having s drawings wherein a Preferred form of the w arouate branches so and 52 extending partially present invention s Clearly S around the shaft 24, the branch 62 being disposed I th dr-a radially outward of the branch of the delivery Figure 1 is alongitudinal cross section of a passage 45, I Pu p uni-t Qmbfldying a preferred form of the A passage 63 has arcuate branches 64 and 85 present invention. which connect with suction ports 88 and In of the Fi ure 2 i a cross section o i e -2 f pump unit I8. The passage 63 has a threaded ure 1. a 1 opening 12 which forms an inlet connection for Figure 3 is a cross section on line 3-3' of Figthe pump unit asawwhole, A wall 14 which sepaure 1'. 7 rates the passages 58 and 63 is formed with an Figure 4 is a cross section on line 4-} of Fig- 50 o ening 16 which forms the seat for a check valve ure 1. 18. The latter permits free flow from the inlet Figure 5 is a cross section on line 5--5 of Figport 12 to the passage 58 but prevents return flow. ure 1. I ,Apassage has branches 82 and 84 which con- Figure 6 is a cross section on line 8-6 of Fignect with outlet ports 88 and 88 of the pump unit ure 1.

I8. The passage has a lateral branch 90 which opens into the passage 46 and an outwardly extending branch 92 which is intersected by a transverse bore 94. The branch 92 connects with a pipe connection 96 forming the discharge outlet of the pump unit as a whole.

The bore 94 has a reduced diameter seat portion 98 adjacent the lefthand wall of passage 92 in Figure 4' and extends beyond the seat portion 98 to connect with a pipe connection I forming an overflow port for the unit as a Whole. Slidably mounted in the bore 94 is a relief valve I02 having a conical valve portion I04 normally closing the seat 98. The end of the bore 94 is closed by a cap I06 having therein an adjustable pilot relief valve I08 adapted to control the operation of valve I02. The construction and operation of the valve I 02 and its control by the pilot relief valve I08 are described in detail in the patent to Harry F. Vickers, No. 2,043,453, to which reference is made for further detail. Briefly, the valve I02 acts to maintain the passage 02 cut ofi from communication with the relief passage I00 until a predetermined maximum pressure is reached in t he passage 92, at which point the valve I02 opens .to whatever degree may be required to prevent the pressure from rising beyond that point.

As seen particularly in Figure 3, there is formed in the body a small bore H0 provided with three spaced enlargements II2, II 4 and H6. The upper end of the bore I I0 communicates with the extension 92 of passage 60 through a duct I I8.

A duct I20 connects extension 92 with the enlargement H2, A duct I22 connects the port I00 with the enlargement II6. Slidable in the bore I I0 is'a valve spool I24 which is urged upwardly in Figure 3 by a spring I 26. The latter is adjustable by means of a screw I 28. I It will be seen that the spool I24 is shiftable in response to pressure variations in extension 92 and, when shifted downwardly by a rise in pressure, connects the central enlargement H4 with the overflow port I00, while, when the valve is shifted upwardly by a fall in pressure, the central enlargement H4 is connected with the pump discharge pressure at extension 92.

As seen in Figur 1, the pump unit I6 is provided with a pair of circumferential grooves I30 which communicate with the inner end of the slots in which the vanes of unit I6 slide. circumferential grooves I30 connect by a duct I32 with the central enlargement II 4 in valve bore IIO. Similar circumferential grooves are preferably provided in connection with the pump unit I8 but are permanently connected with the pump pressure supply ina manner well known in the art.

In operation, referring particularly to the circuit diagram of Figure 9, it will be seen that, with both pump umts I6 and I8 being driven by the rotation of drive shaft 24, fluid will be taken in through the inlet port I2, a minor fraction going through passage 63 to the inlet ports 68 and "I0 of pump unit I 8 and a major portion passing through check valve 78 and passage 58 to the inlet ports 42 and 44 of pump I6. The units transfer the fluid to their respective delivery ports, such fluid passing from the passages 46 and 80 past the relief valve I02 and out through the discharge connection 96.

When the fluid requirements of the device which is being driven by the fluid output of the pump are such as to impose only light or medium resistance to the flow of fluid, the pressure in discharge conduit 80 will be low, and the spring I26 will hold the valve I24 in its righthand posi- These I tion in Figure 9. Accordingly, the pump discharge pressure will be connected through duct I20, enlargements II 2 and. H4, and duct I32 to the circumferential grooves I30. Thus, fluid pressure is maintained beneath the vanes of the unit I6 to keep them projected into tight contact with the circumferential walls of the pump working chamber. This operation of unit I6 is conventional and identical to that of the unit I8 under these conditions.

As soon as the load device imposes additional resistance so that the pressure in discharge conduit builds up sufiiciently to push valve spool I24 to the left in Figure 9, the circumferential grooves I30 become connected to the exhaust side of the pump through duct I 32, enlargements H4 and H6, duct I22 and port I00. The pressure in passage 46, however, is applied adjacent the discharge ports 38 and 40 to the radially outer end of the vanes and, accordingly, causes them to retract inwardly, thus opening a free path from the discharge ports 38 and 40 to the suction ports 42 and 44. Accordingly, the vanes around the entire circumference vof the rotor are subject to full pump pressure from the unit I8 applied to their outer end, and they are thus prevented from being projected by centrifugal force into contact with the walls of the pump chamber.

The discharge pressure, although it backs up into the suction ports 42 and 44 of pump unit I6, is prevented from bypassing to tank by the check valve 78. In this way, a higher degree of pressure may be built up in the discharge port oi. the pump by the small-volume pumping um't I8, and the large-volume unit I6 is rendered ineffective as a pump. The valve I02 acts in the manner of a conventional relief valve to limit the maximum pressure which can be applied to the pump as a whole.

It will be seen that a two-volume pumping unit of this character is particularly adapted to those types of circuits wherein a large volume of fluid is required against a fairly low pressure and at other times a smaller volume is required at a much higher pressure. Circuits of this nature are commonly found in machine tool drives wherein the large volume is required for rapidly advancing a machine part to its working position and wherein the smallvolume is required for slowly feeding the part on its actual working stroke.

It will be noted that, during the operation of the small-volume pump alone, the large-volume pump is not bypassed but is rendered entirely non-operative by the action of fiuid'pressure on the radial vanes. In this way, the wear on the ends of the vanes as well as the wear on the peripheral face of the pumping chamber is materially reduced as compared with previous methods' of unloading a pump of this nature.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A pump unloading system for rotary vane type pumps of the type having a vane-projectin'g pressure chamber effective when the pump is in operation to project the vanes into operative position, said pump having a suction inlet munication with said outlet for maintaining presthe effective operation of the first pump, a valve for selectively causing fluid pressure to build up or to fall off in said chamber, and a check valve on the suction side of said pump to prevent exhausting of fluid from the discharge to the suction side when pressure falls off in said chamber and the vanes are consequently retracted from operative position.

2. A rotary vane type pump having an inlet and an outlet and alternately retractable and extendable vanes for sealing the passage of fluid between the pump inlet and the pump outlet, a

check valve at the pump inlet, means for selectively controlling the application or removal of pressure to said vanes to at times maintain the vanes continuously retracted whereby such sealing is prevented and the pump is rendered inoperative while continuing to rotate, and means for maintaining pressure in said outlet during nonoperation of said pump.

3. A rotary vane type pump having an inlet and an outlet and alternately retractable and extendable vanes for sealing the passage of fluid bemon drive shaft, one of said pumps being of the rotary type and having working elements adapted to be selectively rendered inoperative during rotation of the pump or placed into operation, and

v fluid pressure applying means for selectively effecting such inoperativeness or operation, another of said pumps remaining in operation and being connected to said pressure applying means during inoperativeness of the first pump' whereby pressure is maintained available for said pressure applying means.

5. A multiple delivery rate pumping unit comprising a plurality of pumps driven from a common drive shaft, one of said pumps being of the rotary type and having working elements. adapted to be selectively rendered inoperative during rotation of the pump or placed into operation, fluid pressure applying means for selectively effecting such inoperativeness or operation, another of said pumps remaining in operation and being connected to said pressure applying means during inoperativeness of the first pump whereby pressure is maintained available for said pressure applying means, and a check valve connected with the first-mentioned pump for preventing backfiow therethrough while the pump is inoperative.

6. A multiple delivery rate pumping unit comprising a plurality of pumps driven from a common drive shaft, one of said pumps being of the rotary type and having working elements adapted to be selectively rendered inoperative during ro tation of the pump or placed into operation, fluid pressure applying means for selectively effecting such inoperativeness or operation, another of said pumps remaining in operation and being connected to said pressure applying means during inoperativeness of the first pump whereby pressure 'is maintained available for said pressure applying means, and a check valve located in the inlet of the first-mentioned pump for preventing backflow therethrough while the pump is inoperative.

BURTON J. WILSON.

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