US2530242A

US2530242A - Pump or motor for power transmissions

Info

Publication number: US2530242A
Application number: US629039A
Authority: US
Inventors: Ferris T Harrington
Original assignee: Vickers Inc
Current assignee: Vickers Inc
Priority date: 1945-11-16
Filing date: 1945-11-16
Publication date: 1950-11-14
Anticipated expiration: 1967-11-14

Description

Nov. 14, 1950' F. T. HARRINGTON 2,530,242

PUMP OR MOTOR FOR POWER TRANSMISSIONS Filed Nov. 16, 1945 3 Sheets-Sheet 1 IN V EN TOR. Fees 7. ffiaqzvz rom NOV. 1950 F. 'r. HARRINGTON 2,530,242

PUMP 0R MOTOR FOR POWER TRANSMISSIONS Filed Nov. 16, 1945 3 Sheets-Sheet 2 INVEN TOR. 7755515 I 1%FF/N5'TUN BY (Q fir ram/5."

Nov. 14, 1950 F. T. HARRINGTON 2,530,242

PUMP OR MOTOR FOR POWER TRANSMISSIONS Filed Nov. 16, 1945 3 Sheets-$heet 3 100 i L I05 II J J h 1,1 IO 6 27 n -|o2 59 FIG. 5

1 IL I) 55 I "a T O fi LEE-7' 3|- ms I02 1' I05 I FIG.6

INVENTOR.

FERRIS T. HARRINGTON ATTORNEY Patented Nov. 14,1950

PUMP OR MOTOR FOR POWER TRANSMISSIONS Ferris '1. Harrington, Detroit, Mich, assignor to Vickers Incorporated, Detroit, Mich, a corporation of Michigan Application November 16, 1945, Serial No. 629,039

7 Claims.

This invention relates to power transmissions,

particularly to those of the type comprising two or more fluid pressure energy translating devices, one of which may function as a pump and another as a fluid motor.

The invention relates specifically to a pressureoperated, volumetric control device for use with fluid prnps and motors of the axial piston type having a swinging yoke for varying the disthe case temperature from increasing excessively when the device operates for long periods of time in the neutral position.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred form of the present invention is clearly shown.

In the drawings:

placement of the device. In pumps of this gen- 1. Figure 1 is a sectional view of a fluid energy eral class, the pumping action is created by pistons reciprocating within bores of a cylinder block, the angle of which with respect to the drive shaft may be changed by swinging the yoke.

translating device incorporating a preferred form of the present invention.

Figure 2 is a plan view of a portion of the invention shown in Figures 1 and 3.

As the angle of the cylinder block with respect Figure 3 is a view similar to that of Figure 1 to the drive shaft is decreased, the length of stroke of the pistons is decreased, resulting in a relatively diminished volumetric output. If theyokeis. swung to the completely neutral posibut showing the parts of the invention in a different position.

Figure 4 is a plan view of a portion of the invention shown in Figures 1 and 3.

tion, the cylinder block will be in axial alignment Figure 5 is a partial sectional view taken on with the drive shaft, and, although the rotation of the block continues, there is no relative motion between the pistons and the valve block, and the output becomes zero.

It has hen the practice in the past to provide pressure-operated, volumetric control mechani'sms with variable displacement devices of this generalclass which serve the purpose of maintaining pressure within a predetermined range, but varying the volume of fluid as required'by the hydraulic system. In some applications the pump may be required to operate for long periods at zero displacement and full pressure which may, because of the heavy loading of the bearings and other parts, cause overheating of the pump mechanism unless special provisions are made to cool the pump casing or the fluid in it.

It is an object of the present invention to provide an improved pressure-operated, volumetric "control device for use with pumps and motors of the general class mentioned.

It is also an object of this invention to provide for this general class of fluid devices an improved pressure-controlled,volumetric control mechanism which is capable of automatically diminishing volumetric output to practically zero while, at the same time, maintaining th"e-.pressure at a predetermined, constantly regulated value.

:It is also an object of this invention to provide ansimproved pressure-operated, volumetric control mechanism which, while reducing volumetric output to practically zero, will not only maintain maximum pressure in the system but which is provided with a novel means for preventin line 5-5 of Figure 1.

Figure 6 is a partial sectional view taken on line 6-6 of Figure 1.

Referring now to Figure 1, there is shown a pump of the axial piston type having a casing member In in which is journalled a main drive shaft I2 having a flange l4. Connected to the flange M in sockets, not shown, are a plurality of piston rods [6 having pistons it at their opposite ends shiftable within bores 19 of a cylinder barrel 2!! which is connected to the drive shaft II for rotation thereof in the well-known manner.

The cylinder barrel 20 is adapted to rotate against a valve plate 22 rigidly connected to a swinging yoke 24, the latter being pivotally connected within the casing member H) by means 01 a suitable pintle construction 26. As the cylinder barrel 20 rotates, the piston it will cooperate with ports in the valve plate which are connected to inlet and outlet passages, within the casing member ill, so as to take in fluid from the inlet passage on the suction stroke and force fluid out through an outlet passage and an outlet connection 21 on the pressure stroke of said pistons.

Thus, as shown in Figures 5 and 6, the casing I0 is provided with duplicate passages 29 and 3|, the former of which is connected to an inlet connection 33 and the latter of which is connected to the outlet connection 21. Each pintle assembly 26 is provided with a plurality of ports 35 with which the inlet and outlet casing passages 29 and 3| are adapted to register.

Likewise, the yoke arms are provided with duplicate passages 31 which register with another set of .ports 39 provided in the pintle assemblies 26. Only on'eot the yokearm passages 31 is shown in Figure '5 which-is adapted-to serve as an inlet passage through which fluid 'flows from the upper pintleassembly to one of duplicate ports 43 in the valve plate 22. One of the ports 43 is connected to an arcuate inlet port 45 in the valve plate 22 while an arcuate outlet port 41 in the valve plate 22 is connected to a duplicate of the port 43, not shown. The latter port is connected by a duplicate of the yoke arm passage 31 to the ports 39 of the opposite pintle assembly 26. The valve plate inlet and outlet ports 45 and 41 cooperate with ports formed at the end of the piston bores I9 on the suction and pressure stroke of the pistons.

The interior of the casing I0 may be bled by means of a conduit 53 connected to a drain port 54 of the casing member I0 and to a tank 55. The tank 55 is connected to the inlet connection 33 by a conduit 51. A pressure delivery conduit 59 is connected to the outlet connection 21 and is adapted to be connected to the power side of the transmission, not shown, in the conventional manner.

Mounted on the casing member I0 is a pressure control housin 28 within which is shiftably mounted a pressure control valve 30 for the purpose of limiting the maximum pressure of the pumping device and controlling the admittance of pressure fluid to an actuating piston 32. Piston 32, the closed end of which is linked to yoke 24, is shiftably mounted upon a piston guide 34 which is connected to housing 28 and extends into the interior of easing I0. Piston guide 34 has a longitudinal'stepped passage 36 intersecting a longitudinal bore 38 of housing 28 which is controlled by valve 30 in such a manner as to normally block communication between the discharge side of the pumping device and passage 36, the latter oi which leads directly to the closed end of piston 32. A hollow cylinder 40 having a plurality of elongated ports 4| surrounds piston 32 within casing member I0 so that a chamber 42 is formed therein and is rigidly mounted within a bore 44 of casing member I0 so that a flange 46 of cylinder 40 abuts a shoulder 48 of bore 44. A spring 49 mounted within chamber 42 abuts a flange 50 of piston 32 biasing the piston 32 to one limit 01' its travel and setting the original maximum angle of yoke 24 for maximum output of the pumping device. A transverse passage 52 in guide portion 34 which intersects passage 36 is normally blocked from communication with chamber 42, and consequently the interior of casing member I0, by piston 32. Transverse passage 52 is so placed that upon the control valve 30 admitting pressure fluid to piston 32 the latter will have to shift yoke 24 almost to the neutral position before flange 50 will break over the passage 52.

It should be noted that transverse passage 52 may be so placed in guide portion 34 so that the angle of the yoke 24 may be reduced to any angle between maximum and zero so as to limit the minimum output of the pumping device to the volume desired.

As is more clearly shown in Figure 4 valve 30 is shiftable within a hollow sleeve 56 provided with tear drop shaped ports 58 in alignment with a groove 60 and ports 62 spaced apart from ports 58 in alignment with a groove '64. Sleeve 56 is inserted in bore 38 of housing 28 so that a flange 66 of said sleeve abuts a shoulder 68 of bore 38 and so that groove 60 registers with and overlays passage 36 and groove g 64 registers with and overlays a passage in housing 28 connecting chamber 42 to bore 38.

Control valve 30' consl'stsof apiston I2 prowided with spaced apart'lands I4, 16, I8 and00.

Lands'TI-"and I6 control the admission of pressure fluid to passage 36. Land I8 and control passage I0 permitting fluid to escape from piston 32 upon valve 30 shifting back to its original position when pressure decreases below the setting of valve 30. Piston I2 is provided with a head 82 which is partially rounded so as to rest properly against a seat 84 formed in a shift able seat and spring retainer member 86. A spring 88 placed within the left end of bore 38 abutting retainer 66 determines the maximum pressure attainable by the pumping device and normally biases valve 30 so that land 16 blocks port 58 of sleeve 56 from communication with passage 36. An adjustable screw 90 abuts the left end of spring 88 and closes the left end of bore 38. Valve 30 is adapted to be limited in its rightward movement by a portion 92 of a closure member 94 which extends into bore 38, the latter closing the right end of bore 38.

Portion 92 being smaller in diameter than that of bore 38 a chamber 96 is formed in the right end of bore 38 between closure member 94 and the right end of sleeve 56. A passage 98 in housing 28 intersects chamber 96. A passage I00 intersectin a passage I02 which connects to the outlet passage 3|, by means of a passage I03 (Figure 6), registers with passage 98 so as to place chamber 96 in communication with the discharge side of the pumping device. The terminus of the passage I03 opening to the exterior of the casing I0 is closed by a suitable plug I05. Portion 92 is provided with a longitudinal passage |04 which intersects a transverse passage I06 in communication with chamber 96 providing a means of communication between the right end of valve 30 and the discharge side of the pumping device.

Land I4 of valve 30 is provided with a plurality of notches I08 which permits pressure fluid entering chamber 96 to be metered into tear drop ports 58 into passage 36 through the medium of said notches as land I6 breaks over ports 58. A diagonally drilled passageway I I0 connects the left end of bore 38 with passage I0 in order to take care of the fluid displacement caused by leftward shifting of valve 30 into said bore.

In operation, with the pump running and the angle of the yoke 24 as shown in Figure 1 the volumetric output of the pump is at maximum value. Pressure fluid which is discharging through outlet connection v2I acts against the right end of valve 30 by means of passage I03 connected to the outlet passage 3|, passage I02, passage I00, housing passage 98, chamber 96, transverse passage I06 and longitudinal passage I04 in portion 92. Pressure fluid in chamber 96 is prevented from entering passage 36 through the medium of notches I08 and tear drop ports 58 by land I6 of valve 30. This predetermined volumetric output will continue until the pressure in the system reaches a point high enough to overcome the resistance of spring 88 when valve 30 will begin to shift to the left. A the left end of piston 30 shifts through sleeve 56 into the bore 38 the slight quantity of fluid displaced thereby may flow into passage I0 by means of passage H0 and to drain port 54 by means of chamber 42 and cylinder ports 4|. As land I6 breaks over ports 58 pressure fluid will begin to h a bemetered through notches I33 into ports l3 through grooves I to passage 36 and by means of passage 33 to the closed end of piston 32. As land It continues to break over ports 58 a gradually increasing amount of fluid entering passage 30 will continue to shift piston 33 against the reslstance offered by spring 49 to change the angle of yoke 34, shortening the length of stroke of pistons i3 and decreasing the volumetric output of the pumping device. Piston 32 will continue to shift until the flange portion 53 thereof breaks over transverse passage 32 in guide portion 34.

As shown in Figure 3 the complete output of the pump, which is now nearly zero because of the angle of the cylinder barrel in relation to the drive shaft. is now by-passed into the interior of the casing member II by means of passage I3, chamber 42 and ports 4|. From the interior of the casing it this fluid may bleed out of drain port 84 to the tank 55 by means of the conduit 83.

When the pressure in the system decreases to a point below the resistance of spring 33 control valve 30 will be shifted rightwardly by theforce of said spring. At the point that flange 33 of piston 32 closes transverse passage 82 and land 16 of valve 30 blocks ports I! of sleeve I! from the discharge side of the pump, land II. no longer blocks communication between ports '3 and ports 64. Trapped fluid in piston 32 and passage 38 may then escape to the interior of the casing ill in order to allow piston 32 to shift by the force of spring 48 to the position shown in Figure l. Fluid escapes from piston 32 through passage 36, groove I of sleeve 58, ports I8, and is guided by lands I3 and 30 of valve 30 to ports 02 and by means of groove Q4 of sleeve 56, passage 10, chamber 42, and ports 4! and cylinder 40 to the interior of the casing from where it is discharged through drain port 54. When piston 32 has shifted completely the angle of yoke 24 is as shown in Figure 1 and the volumetric output of the pump is again at maximum value.

It should be noted that when the maximum pressure in the system as determined by spring 30 has been reached and control valve 30 has shifted sufllciently so as to permit fluid to enter passage 34 to shift piston 32, that the volumetric output of the device will be practically zero. Due to the fact that this small output is bled into casing I l and from casing it back to the tank It by means of drain port 84 and conduit 51, the heat created by such operation will be practically nil.

It should also be noted that the transverse passage I! may be placed in piston guide 34 relative to the cracking point of the flange portion IQ of piston 33 so that the minimum volumetric output of the pumping device may be regulated to supply Just the right amount of minimum output necessary to maintain the desired pressure in the system or to flt the minimum needs of any installation.

It should also be noted that the invention is adaptable to be used with practically any fluid energy translating device having a swinging yoke for varying the displacement of the device simply by connecting the discharge side of the device to passage 93 of housing 28 and so that ports 4| of cylinder 40 are in communication with the interior of the casing member.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms 6 might be adopted, all coming within the the claims which follow.

What is claimed is as follows:

1. A fluid energy translating device of the variable displacement type comprising in combination a casing having high and low pressure terminals, a shiftable member for varying the displacement of the device and a discharge outlet for circulation of a small flow of fluid for cooling purposes, a volume control mechanism comprising pressure responsive actuating means connected to the member for shifting the same and having an expansible pressure chamber in communication with the high pressure terminal of the device, and means forming a by-pass passage hydraulically connected to said chamber and controlled by the actuating means, said by-pass passage being connected to said discharge outlet through the interior of the casing and being opened and closed by the actuating means at predetermined points within its range of movement. v

2. A fluid energy translating device of the variable displacement type comprising in combination a casing having high and low pressure terminals, a shiftable member for varying the displacement of the device and a discharge outlet for circulation of a small flow of fluid for cooling purposes, a volume control mechanism comprising pressure responsive actuating means connected to the member for shifting the same, and having an expansible pressure chamber in communication with the high pressure terminal of the device, means forming a by-pass passage hydraulically connected to said chamber and controlled by the actuating means, and means resiliently biasing the actuating means to one limit of its travel and closing the by-pass passage, said by-pass passage being connected to said discharge outlet through the interior of the casing and being opened by the actuating means in response to increases of pressure at a predetermined point within its range of movement.

3. A fluid energy translating device of the variable displacement type comprising in combination a casing having high and low pressure terminals, a shiftable member for varying the displacement of the device and a discharge outlet for circulation of a small flow of fluid for cooling purposes. a volume control mechanism comprising pressure responsive actuating means mechanically connected to the member for shifting the same and having an expansible pressure chamber, valve means hydraulically connected to the expansible chamber and to the high pressure terminal of the device for connecting and disconnecting the high pressure terminal from scope of the expansible pressure chamber, and means forming a by-pass passage hydraulically connected to the expansible chamber and controlled by the actuating means, said by-pass passage being connected to the discharge port through the interior of the casing and being opened and closed by the actuating means at predetermined points within its range of movement.

4. A fluid energy translating device of the variable displacement type comprising in combination a casing having high and low pressure terminals, a shiftable member for varying the displacement of the device and a discharge outlet for circulation of a small flow of fluid for cooling purposes, a volume control mechanism comprising pressure responsive actuating means mechanically connected to the member for shifting the same and having an expansible pressure chamber, valve means hydraulically connected to the expansible chamber and to the high pressure terminal for connecting and disconnecting the high pressure terminal from the expansible chamber, means forming a by-pass passage hydraulically connected to said chamber and controlled by the actuating means, and resilient means biasing the actuating means to one limit of its range of travel and closing the by-pass passage, said by-pass passage being connected to the discharge outlet through the interior of the casing and being opened and closed by the actuating means at predetermined points within its range of movement.

5. A fluid energy translating device of the variable displacement type comprisin in combination a casing having high and low pressure terminals, a shiftable member for varying the displacement of the device and a discharge outlet for circulation of a small flow of fluid for cooling purposes, pressure responsive actuating means connected to said member for shifting the same and having an expansible pressure chamber hydraulically connected to the outlet, and means forming a by-pass passage hydraulically connected to the chamber and to the interior of the casing and controlled by the actuating means, said actuating means normally closing the passage and opening the passage in response to predetermined increases of pressure at the outlet within its range of movement whereby when the device is operating at small displacement, a small fluid circulation may be established through the casing for cooling purposes.

6. A fluid energy translating device of the variable displacement type comprising in combination, a casing member havin an inlet and an outlet, a shiftable member for varying the displacement of the device and a separate discharge port leading from the interior of the casing, pressure responsive actuating means connected to said member for shifting the same and having an expansible pressure chamber in communication with the outlet, means forming a by-pass passage hydraulically connected to the pressure chamber and to the interior of the casing and controlled by the actuating means, said actuating means normally closing the passage and opening the passage in response to predetermined increases of pressure at the outlet within its range of movement whereby when the device is operating at small displacement a small fluid circulation may be established through the casing for cooling purposes, and means for supplying fresh cooled fluid to the inlet of the device.

7. A fluid energy translating device of the variable displacement type comprising in combination a casing member having an inlet and an outlet, a shiftable member for varying the displacement of the device, and a separate discharge port leading from the interior of the casing, pressure responsive actuating means connected to said member for shifting the same and having an expansible pressure chamber hydraulically connected to the outlet, means formin a by-pass passage hydraulically connected to the actuating means and to the interior of the casing and controlled by the actuating means, said actuating means normally closing the passage and opening the passage in response to predetermined increases of pressure at the outlet within its range of movement, and a casing fluid circulating and cooling circuit including a fluid supply source connected to the inlet of the device, and a conduit connecting the separate discharge port to the fluid supply source whereby when the device is operating at small displacement a small fluid circulation may be established through the casing for cooling purposes, and the device is continually supplied with fresh cooled fluid.

FERRIS T. HARRINGTON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,087,772 Bempthorne July 20, 1937 2,140,633 Kooks Dec. 20, 1938 2,177,098 Doe et a1. Oct. 24, 1939 2,284,109 Vickers May 26, 1942 2,284,897 Harrington June 2, 1942 2,303,955 Rose Dec. 1, 1942 2,403,371 Ifleld July 2, 1946 2,429,403 Deschamps Oct. 21, 1947 2,433,222 Huber Dec. 23, 1947