US2553655A

US2553655A - Pump

Info

Publication number: US2553655A
Application number: US654314A
Authority: US
Inventors: Kenneth R Herman; Ralph L Tweedale
Original assignee: Vickers Inc
Current assignee: Vickers Inc
Priority date: 1946-03-14
Filing date: 1946-03-14
Publication date: 1951-05-22
Anticipated expiration: 1968-05-22

Description

May 22, 1951 K. R. HERMAN HAL 2,553,655

PUMP

Filed March 14, 1946 2 Sheets-Sheet 1 Z: z- E Z l I I I4 '6 ils a n V /1 A Mia-w nl was Hr ron/vw May 22 1951 K. R. HERMAN erAL 2,553,655

PUMP Filedmarch l14, 194e 2 sheets sheet g 5'7- TURA/Er Patented May 22, 1951 PUMP Kenneth R. Herman, Franklin, and Ralph L. Tweedale, Birmingham, Mich., assgnors to Vickers Incorporated, Detroit, Mich., a corporation of Michigan Application March 14, 1946, Serial No. 654,314

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 is more particularly concerned with a iiuid pressure energy translating device of the multi-piston and cylinder types having mechanically operated positively timed valving for controlling the distribution of iiuid to and from the cylinders. Devices of this characterv are widely used in systems operating .at very high pressures 4and frequently operate at very high speed. One disadvantage frequently encountered with units of this type is the production of considerable noiseand a large part of this noise has been found to be generated as fluid pressure shock originating from improper timing of the admission and release of pressure fluid to each cylinder.

Where the device is of the type using a rotating cylinder block having individual ports which cooperate with a stationary valve member having main inlet and outlet ports. thev valve timing is not capable of adjustment after the device has been assembled since it is determined by the length of the portsy in the valve member.

Many attempts have been made to improvethe action of this type of valve mechanism so as to make it noise free under all the various operating conditions encountered, but these attempts have heretofore not been entirely successful. y

It is an object of the present invention to provide an improved uid pressure energy translating device which retains, the advantages of the positive mechanically operated valving, and yet which is capable of operating silently throughout a greater range of speed, pressure, and piston stroke.

A further object is to provide. in a device of this character, a valving structure in which the normal mechanicalvalving has a lengthened cutoIf adacent dead-center piston position which blocks each cylinder in turn during, a substantial part of the piston stroke, and to provide in addition auxiliary valving means utilizing check valves for determining the exact time of opening of each cylinder to the high pressure or low pressure port of the device or to both. In this way the advantages of mechanically operated valving such as their usual large open iiow passages are retained without their drawback of noisy operation., Likewise. the` advantages of quiet operation obtainable when, check valves are. utilized and, because the 'check valve can be made small 6 Claims. (Cl. 10S-162) and light, no diiculty is experienced from inertia effects, seat pounding, etc., which would be troublesome if the check valves are made large enough to carry the entire cylinder delivery.

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:

Figure l is a longitudinal sectional view of a reversible variable stroke pump embodying a preferred form of the present invention.

Figure 2 is an end view of the cylinder block of the pump of Figure l.

Figure 3 is an end view of the valve plate of the pump. of Figure 1.

Figure 4 is a developed view illustrating diagrammatically the action of the valve mechamsm.

Referring now to Figure 1, there is illustrated a pump comprising a main housing Illl having an. end cover I2. A drive shaft I4 is j'ournalled on. bearings IIiv and has a driving ange I8 at its; inner end. The ange I8 carries a plurality of' sockets 2li which are articulated to connecting' rods 2-2 having pistons 24 articulated thereto'atA the opposite end. Pivotally mounted in the cas-- ing I0 on hollow trunnions 26 is a two-armed swinging yoke 28, arms of which are hollow for' passage of iluid to and from the pintle 26. The yoke carries a stationary valve plate 3i) having two

arcuate ports

32 and 34 as shown in Figure 3. The valveplate ports communicate respectively withthe passages formed in the yoke 28 and provide the main inlet and outlet passages for the pump. A cylinder block 36 is provided with a plurality of aXial cylinder bores 38 having indivdual ports 40 adapted to register with the valve plate ports alternately as the block rotates in contact with the valve plate. rIhe cylinder -block 3B isjournalled on a pin 42 by means of a bearing 44 while a spring 45 exerts a light'pressure urging the cylinder block into contact with the valve plate 30. The cylinder block 3.6 is driven in synchronism with the, drive shaft I4 by means ofV a Cardan shaft 48 having universal joints 5l! at its oppositeA end.

They structure thus far described is typical of prior art construction, and the present improvementy concerns the. means for valving the fluid to and from the cylinder bores 38. There is provided. in the cylinder block a plurality of indiv'idual check valves 52v one for each cylinder. The check valves 52 have their inlet side in com- 'shown in dotted lines.

the next adjacent cylinder in a clockwise direc-k tion which would be the intended direction of rotation of the cylinder barrel shown in Figurel Y 2. The terminus of each passage 56 is also located radially inward from the edge of the ports 40.

Referring now to Figure 3, and bearing in mind that clockwise rotation of the cylinder barrel in Figure 2 appears as counterclockwise rotation in Figure 3, the

valve ports

32 and 34 have their leading edges located a considerable angula1` distance from the vertical center line which is the point of piston dead-center while their trailing edges are located approximately at the normal distance from the Vertical center linethis distance being substantially one-half the length of each cylinder port 43. Each

port

32 and 34 also has an

inward extension

58 and 60, respectively, which registers with the ends of the passages 56 in turn.

The flat surface between the end of the

ports

32 and 34, that is, the portion which effects cut- 'o of each cylinder from both ports, is thus considerably longer than the cylinder port 40, and would normally block each cylinder for a signicant part of its piston stroke. One of these cut-olf portions is provided with a depressed cavity or recess 62 of the shape shown. Assuming that the port 32 will be the pressure or outlet port for normal forward delivery of the pump, and port 34 the suction or inlet port, the cavity 62 is connected with the port 34 by means of a Vposition illustrated, the axis of cylinder block 36 is coincident with the axis of shaft l4and no re- ;ciprocation ofthe pistons 24 takes place. The pump is thus in neutralqposition and its iiuic youtput is zero. 1f the yoke 23 be swung away from the observer in Figure 1, the port 34 becomes the inlet port and port 32 the outlet port, and the quantitative delivery of the pump will vary with the angle through which the yoke is displaced from neutral position. Likewise, for reverse delivery the yoke may be swung towards the observer in Figure 1 to make the port 34 the inlet port and port 32 the outlet port, rotation of the shaft at all times being in the direction top to the right in Figure l.

Referring now to Figures 2 and 3, and particularly to Figure 4, the valve action may be considered. In Figure 4, the parts associated with valve plate 33 are shown in solid lines, and the parts associated with the cylinder barrel 36 are The two ends of the iigure represent bottom dead-center of Figure 3 while the mid-point represents top dead-center. It will be noted that in the position shown in Figure 4, cylinder port 40 for cylinder No. 1 is at bottom dead-center, and with the yoke 28 swung to full forward displacement position, the

4 No. 1 has just cut off from inlet port 34 and the terminus of its check valve passage 56 is just starting to connect with the extension 5B of port 32. Thus, on the first downward travel of its piston, the oil which is trapped in the cylinder bore and port at inlet pressure is compressed at first before the check valve 52 opens. As soon as it is compressed to a pressure equal to that in the outlet port 32, a slight additional compression sufcient to overcome the spring behind the check valve, opens the same and provides for the initial delivery of all oil from said cylinder until port 40 opens to port 32. Since the piston movement is substantially simple harmonic motion, the initial travel of the piston is small in relation to the angular travel of the cylinder barrel so that the check valve 52 need not have a large iiuid carrying capacity. As soon as port 40 establishes connection with port 32, all further delivery from the cylinder takes place through port 4l) until that port is cut off at the trailing edge of port 32 whichr occurs at top dead-center.

Thereafter, the port 40 is cut olf from communication with port 34 for a considerable angular movement of the cylinder block, but is in communication with therecess B2. During the initial retraction movement of the piston, as for example the piston shown at No. 6 in Figure 4, the oil which was trapped in the cylinder bore and port is initially under full delivery pressure, and this holds the check valve 64 tightly on its seat. Retraction of the piston, however, permits this oil to re-expand until it has dropped to a pressure slightly below the pressure inv the inlet port 34 at which time check valve 64 opens permitting intake of fluid through this path. Upon a further movement of the cylinder barrel, port 40 connects with the main portion of port 34, and the remaining part of the suction stroke takes place with all oil going through the port 40.

It will thus be seen that the initial connection of each cylinder with both the inlet and the outlet port is established temporarily through a passage containing a check valve. This provides au automaticcontrol of the point at which ow starts, and allows the trapped oil in the cylinder bore and port to be brought up or down in pressure as required to exactly match the pressure in the valve port to which it is to be connected.

Thus, the actual timing is Varied automatically, depending upon pump speed, operating pressure, and piston stroke, as is necessary under the various conditions. At the same time, the main flow to or from each cylinder takes place through wide clear passages imposing little restriction.

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. In a multi-piston and cylinder liquid pressure energy translating device the combination of a plurality of pistons and cylinders, means for causing relative' reciprocating motion thereof, a main inlet port, a main outlet port. a rotary valve operable in timed relation with the pistons thereof and controlling communication with the main inlet and outlet ports of the device, individual small discharge passages, one for each cylinder, and connecting with the main outlet port during only the beginning of each piston discharging stroke, a check valve in each passage, and separate larger passages, one `for I5 each cylinder, connecting with the main outlet port during a later phase of the piston stroke and also connecting with the main inlet port during the piston return stroke.

2. In a, multi-piston and cylinder liquid pressure energy translating device the combination of a plurality of pistons and cylinders, means for causing relative reciprocating motion thereof, a main inlet port, a main outlet port, a rotary valve carried by the cylinders and operable in timed relation with the pistons thereof and controlling communication with the stationary main inlet and outlet ports of the device, individual small discharge passages, one for each cylinder, and connecting with the main outlet port during only the beginning of each piston discharging stroke, a check valve in each passage, and separate larger passages, one for each cylinder, connecting with the main outlet port during a later phase of the piston stroke and also connecting with the main inlet port during the piston return stroke.

3. In a multi-piston and cylinder liquid pressure energy translating device the combination of a plurality of pistons and cylinders, means for causing relative reciprocating motion thereof, a main inlet port, a main outlet port, a rotary valve operable in timed relation with the pistons thereof and controlling communication with the main inlet and outlet ports of the device, individual small discharge passages, one for each cylinder, and connecting with the main outlet port at the-start of each piston discharging stroke, a check valve in each passage, separate larger passages, one for each cylinder, connecting with the main outlet port during a later phase of the piston stroke and also connecting with the main inlet port during the piston return stroke, and a check valve opening out of the main inlet port to each cylinder in turn to establish initial connection with the main inlet port.

4. In a multi-piston and cylinder liquid pressure energy translating device the combination of a plurality of pistons and cylinders, means for causing relative reciprocating motion thereof, a main inlet port, a main outlet port, a rotary valve operable in timed relation with the pistons thereof and controlling communication with the main high and low pressure ports of the device, said valving structure having a lengthened portion at one dead-center position of the pistons at which the normal communication of the cylinder is cut off from both high and low pressure ports, individual check valves for each cylinder, and auxiliary means associated with the high pressure port for establishing communication with the high pressure port through each check valve in turn as the corresponding piston starts away from dead-center.

5. In a multi-piston and cylinder liquid pressure energy translating device the combination of a plurality of pistons and cylinders, means for causing relative reciprocating motion thereof, a main inlet port, a main outlet port, a rotary valve operable in timed relation with the pistons thereof and controlling communication with the main high and low pressure ports of the device, said valving structure having a lengthened portion at one dead-center position o the pistons at which the normal communication oi the cylinder is cut 01T from both high and low pressure ports, individual check valves for each cylinder, and auxiliary means associated with the high pressure port for establishing communication with the high pressure port through each check valve in turn as the corresponding piston starts away from dead-center. the valving structure having a lengthened portion at the other dead-center position and a check valve opening out of the main inlet port and eiective to connect each cylinder in turn to the main inlet as the corresponding piston starts .away from dead-center.

6. In a multi-piston and cylinder liquid pressure energy translating device the combination of a plurality of pistons and cylinders, means for causing relative reciprocating motion thereof, a main inlet port, a, main outlet port, a rotary valve operable in timed relation with the pistons thereof and controlling communication with the main high and low pressure ports of the device, said valving structure having a lengthened cut-off of the cylinders from both high and low pressure ports at at least one deadcenter position, and individual check valves, one for each cylinder, for establishing communication of each cylinder with the high pressure port as the corresponding piston starts away from dead-center.

KENNETH R. HERMAN. RALPH L. TWEEDALE.

REFERENCES CITED The following references are of lrecord in the le of this patent:

UNITED STATES PATENTS Number Name Date 924,787 Janney June 15, 1909 1,081,810 Carey Dec. 16, 1913 2,288,768 Zimmermann July 7, 1942 2,313,407 Vickers Mar. 9, 1943 2,418,123 Joy Apr. 1, 1947 FOREIGN PATENTS Number Country Date 285,468 Germany 1915 442,450 Great Britain Feb. 10, 1936 506,684 Great Britain 1939