US2962972A - Power transmission - Google Patents

Description

Dec. 6, 1960 T. VAN METER 2,

' POWER TRANSMISSION Filed July 25, 1958 FIG. 4

INVENTOR. TH EO DORE VAN M ETER I02 BY ATTORNEYS POWER TRANSMISSION Theodore Van Meter, Birmingham, Mich., assignor to Vickers Incorporated, Detroit, Mich., a corporation of Michigan Filed July 23, 1958, Ser. No. 750,350

Claims. (Cl. 103-136) This invention relates the power transmissions, and is particularly applicable 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.

More particularly the invention relates to a rotary, vane type pumping unit having a vane track against which the vanes are biased to cause in and out movement, so as to generate a pumping action.

In order to pump etfectively it is necessary that the ends of the vanes be kept in continuous contact with the vane track. Since pressure forces on the outer ends of vanes traversing the pressure ramps tend to cause the vanes to leave the track, it is necessary that these pressure forces be balanced, either mechanically or by applying pressure to'the Opposite end of the vane. Mechanical counterbalancing is impractical for high pressures. Hydraulic counterbalancing has been accomplished by the prior art in a variety of ways.

One of the earliest and still most widely used forms of pressure counterbalancing is that in which outlet pressure is continuously conducted to the full underside area of all the vanes. While this has proved to be a simple and relatively effective device for maintaining the vanes in contact with the vane track, practical considerations have resulted in a maximum operating pressure of the order of 1000 psi. This is due to the fact that the vanes traversing the suction ramp of the vane track have only the low, inlet pressure on the outer end, although the inner end is continuously subjected to the high, outlet pressure. At pressures above approximately 1000 psi. the oil film between the suction ramp of the vane track and the ends of the vanes tends to break down and the vane track and vanes are soon worn beyond usability. An additional disadvantage of these devices is that the vanes traversing the pressure ramp, although fully balanced hydraulically, sometimes skip or leave the track for brief periods even though centrifugal force continuously urges them toward the vane track.

Another approach to the problem of maintaining contact between the end of the vane and the vane track has been to fully balance the vane as it traverses both the pressure ramp and the suction ramp by the use of porting which maintains the pressure on both the inner and outer end of each vane substantially in phase and equal. Units of this type have been found to be capable of considerably higher pressures than those units discussed above in which outlet pressure is continuously imposed on the inner end of the vanes. Two main difficulties have been encoun tered in devices which employ phased, equal pressures on the inner and outer ends of the vanes. One of these difficulties is that the same previously discussed skipping of the vanes traversing the pressure ramp has been encountered. Another difiiculty is that at high speed, centrifugal force is inadequate to insure continuous contact between the vane and the vane track as the vanes traverse the inlet ramp.

nited States Fatent C It is an object of this invention to provide an improved high speed, high pressure vane pump.

More particularly it is an object of this invention to provide a vane pump in which the vanes are continuously and positively urged into engagement with the vane track but in which the magnitude of the biasing force is small enough to avoid excessive wear between the vane and the track.

It is also an object of this invention to provide a vane pump in which the pressure forces on each vane are in a continuous and controlled outward balance while the vanes traverse both the inlet and outlet ramps.

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

In the drawing:

Figure 1 is a longitudinal section through pumping mechanism embodying the present invention and taken on line 1-1 of Figure 2.

Figure 2 is a section taken on line 2-2 of Figure 1.

Figure 3 is a section taken on line 3-3 of Figure 1.

Figure 4 is an enlarged fragmentary view of a portion of a vane and associated structure.

Figure 5 is a schematic drawing illustrating the hy draulc circuitry of the present invention.

Figure 6 is a fragmentary section taken on line 6-6 of Figure 3.

Referring to Figure 1 there is shown a body 10, a wear plate 12, a ring 14 and a head 16. These members are held together by a plurality of bolts 18, and are sealed at their junctures by O-rings 20. The head member 16 includes a pressure chamber 22 in which is disposed a pressure plate 24 which abuts the ring 14. Dowel pins 25 maintain angular alignment of body 10, wear plate 12, ring 14 and pressure plate 24. Disposed between the wear plate 12 and the pressure plate 24 is a rotor 26 which carries a plurality of vanes 28. The width of ring 14 is slightly greater than the width of rotor 26 and vanes 28 so as to provide a small running clearance. Pressure in chamber 22 is imposed on pressure plate 24 so as to maintain the running clearance substantially constant regardless of pump outlet pressure.

The rotor 26 is supported on and driven by a shaft 30, which is rotably supported in bearings 32 and 34 in body member 10. A shaft seal 36 prevents leakage from the body 10 at the point of egress of shaft 30.

The body member 10 includes an inlet port 38 which leads to an inlet cavity 40. A pair of branched passages 42, only one of which is shown in Figure I, extend to the face of body 10 which abuts wear plate 12, and communicate respectively with inlet ports 44 and 46 in the wear plate 12.

In the region of inlet ports 44 and 46 a plurality of cross-over holes 48 extend through the ring 14 to com: municate with a pair of blind ports 50 in the pressure plate 24. Ports 50 are mirror images of ports 44 and 46.

Head member 16 includes an outlet port 52 which leads from the pressure chamber 22. A pair of diametrically opposed pressure ports 54 and 55, only one of which is shown in Figure 1, effect communication between the rotor chamber and pressure chamber 22. A pair of blind ports 57 are provided in wear plate 12 to axially balance rotor 26 and vanes 28. Ports 57 are mirror images of ports 54 and 55, only one being shown in Figure l.

The ring member 14 forms a generally elliptical vane track 56 which surrounds rotor 26 and vanes 28. The vane track includes a pair of diametrically opposed inlet ramps 58 and 60 across which the vanes move outward as the rotor turns, and a pair of diametrically opposed outlet ramps 62 and 64 which urge the vanes inward.

Truearc portions of the vane track connect the inlet and outlet ramps.

The structure so far described is conventional and it will be recognized by anyone skilled in the art that, as rotor 26 turns in the direction indicated by arrow 66 in Figure 2, fluid will be taken into the spaces between adjacent vanes at the inlet ports 44 and 46 and that that fluid will be discharged through the outlet ports 54 and 55 at an increased pressure.

Referring now to Figure 4, it wil be noted that the vanes 28 include a step 68 which extends the full width of the vane, thus resulting in a vane having a thick outer portion 70 and a narrower inner portion 72. The vane slots 74 are stepped so as to snugly receive both the thick outer portion 70 and the narrower inner portion 72. There is thus formed beneath each vane a pressure chamber 76 and a pressure chamber 78. It should be noted that the thickness of step 68 is approximately one half the thickness of the narrow portion 72 of the vane 28. Thus each vane 28 presents a relatively large area 88 to the pressure existing in chamber 76 and a relatively small area 82 to the pressure existing in the chamber 78. The outer end of each vane 28 is chamfered at 84 so as to make contact with the vane track 56 only at the leading edge 86, thus exposing substantially the entire outer area of each vane to the pressure existing between it and its following vane.

The pressure plate 24 is provided with a pair of undervane ports 88 and 90 which are, to a substantial extent, arcuately coextensive with the inlet ports in the pressure plate 24 and the wear plate 12. These ports 88 and 90 are trenched into the pressure plate 24 as can best be seen by reference to Figures 1 and 3. The radially outward location of ports 88 and 90 is such that they communicate with the chambers 78 which, as heretofore noted, are associated with the step area 82 of each vane. This can be clearly seen by reference to Figure 2. To provide for axial hydraulic balance of the rotor, a pair of blind ports 91 are provided in the wear plate 12, only one being shown in Figure l, which are mirror images of ports 88 and 90.

An additional pair of ports 92 and 94 are trenched into pressure plate 24 so as to communicate with chambers 78. Ports 92 and 94 are substantially coextensive arcuately with the outlet ports 54 and 55 respectively, and these ports communicate with the pressure chamber 22 and outlet port 52 through drilled holes 96. Axial balance of rotor 26 is maintained by the provision of blind ports 97 which are trenched into wear plate 12 and form mirror images of ports 92 and 94.

A pair of ports 98 and 100 extend through the wear plate 12 to communicate through a radial groove 102 with the inlet ports 44 and 46 and the main inlet port 38. A pair of ports 104 and 106 in pressure plate 24 are mirror images of ports 98 and 100 and they communicate through a trenched central recess 107 in pressure plate 24 with the drive shaft opening through rotor 26, and thence with the inlet cavity 40. Ports 98 and 180 have an arcuate length substantially coextensive with that of inlet ports 44 and 46, and are radially located so as to communicate with the chamber 76 at the inner end oi each vane.

A second pair of ports 108 and 110 in pressure plate 24 are radially positioned so as to communicate with the undervane chambers 76 and have an arcuate length substantially coextensive with the arcuate length of outlet ports 54 and 55. Axial balance of the rotor 26 is maintained by mirror image ports 111 in wear plate 12. A drilled passage 112 extends from each of'the ports 1.98 and 110 to communicate with the pressure chamber 22 across one-way back pressure valves 114. Valves 114 are urged by spring 116 in a direction such as to block flow from pressure chamber 22 into the ports 108 and 110. The spring 116 is selected to have a load value such that the pressure in ports 108 and 110 must exceed the pressure in pressure chamber 22 by a predetermined amount before fluid can flow from ports 108 and 110 into pressure chamber 22. In a particular unit which gave excellent performance, spring 116 Was so selected that pres sure in ports 108 and 110 was required to exceed outlet pressure by 25 p.s.i. before fluid could flow into the pressure chamber 22.

Port 108 is connected to port 88 by a pair of intersecting drilled passages as shown at 118. Ports 110 and 90 are connected in a similar fashion as shown at 120. The nature of the drilled connection passage between the ports 108 and 88 and 118 and 90 can be clearly seen by reference to Figure 6.

Operation of the device can best be understood by reference to Figure 5, where a first vane is shown traversing one of the outlet ramps 62 and a second vane is shown traversing one of the inlet ramps 58. Referring first to the vane traversing the outlet ramp 62, it will be noted that full outlet pressure will be imposed on the entire outer end 84 of the vane. Because of the communication between port 54 and port 92, established by passage 96, the pressure in the step chamber 78 will be equal to outlet pressure and to the extent of the area of the step, the vane will be balanced. Since the vane traversing the outlet ramp 62 is moving inward, fluid will be displaced from the chamber 76. This fluid will pass through the conduit 118 to the port 88 which is in communication with chamber 78 of the outward moving vane traversing the inlet ramp 58. Because the area of step 82 is less than the area of the inner end of the vane, it will be understood that more fluid will be discharged from chamber 76 of the inward moving vane than can be accepted by chamber 78 of the outward moving vane. The excess fluid has only one place to go and that is through the passage 112 and over the back pressure valve 114, to the pump outlet port 54. As heretofore noted, the fluid cannot pass over back pressure valve 114 until the pressure in ports 108 and 88 exceeds the pressure in the outlet port by a predetermined amount. It will thus be apparent that the vane moving over the outlet ramp will be positively urged outward by a force which is the product of the area 80 and the pressure differential existing across back pressure valve 114. Thus, the outward pressure bias on a vane traversing an outlet ramp can be easily selected to be any desired optimum value so as to maintain vane tracking and at the same time avoid wear.

Considering now the vane traversing the inlet ramp 58, it will be seen that the outer end area 84 is exposed only to inlet pressure, while at the same time the area 82 of the step is exposed to a pressure slightly higher than outlet. Thus, the vane will be positively urged outward against the vane track. This outward bias against the inlet ramp can be controlled so as to maintain the desired tracking, and yet stay below excessive wear producing proportions, by a proper selection of the area of step 82. The large area 80 has no outward force producing eflect on the vanes traversing the inlet ramp since it is connected by the conduit 102 to the inlet port.

There has thus been provided a simple, low cost, vane pump in which the vanes are positively biased outward by a controlled pressure produced force, while traversing both the inlet and outlet ramps. Tracking of the vanes is thus assured while at the same time, excessive wear is eliminated.

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 vane type pump having inlet and outlet ports, the combination of: a rotor; a plurality of slots in said rotor; a vane slidable in each of said slots; a vane track having suction and pressure ramps; separate surfaces providing large and small areas mechanically associated with each vane, said areas being so oriented as to be effective under pressure to urge the vanes against the track; a

passage eflecting common fluid communication between the large area of a vane traversing a pressure ramp and the small area of a vane traversing a suction ramp; and means associated with said passage for maintaining the pressure on said large and small areas a predetermined amount above outlet pressure during the period of common communication.

2. In a vane type pump having inlet and outlet ports, the combination of: a rotor; a plurality of slots in said rotor; a vane slidable in each of said slots; a vane track having suction and pressure ramps; separate surfaces providing large and small areas mechanically associated with each vane, said areas being so oriented as to be effective under pressure to urge the vanes against the track; a passage effecting common fluid communication between the outlet port, the large area of a vane traversing a pressure ramp, and the small area of a vane traversing a suction ramp; and means associated with said passage for maintaining the pressure on said large and small areas 1 predetermined amount above outlet pressure during the period of common communication.

3. In a vane type pump having inlet and outlet ports, the combination of: a rotor; a plurality of slots in said rotor; a vane slidable in each of said slots; a vane track having suction and pressure ramps; separate surfaces providing large and small areas mechanically associated with each vane, said areas being so oriented as to be effective under pressure to urge the vanes against the track; a passage effecting common fluid communication between the outlet port, the large area of a vane traversing a pressure ramp, and the small area of a vane traversing a suction ramp; and means associated with said passage for maintaining the pressure on said large and small areas a predetermined amount above outlet pressure during the period of common communication, said means comprising a one-way, back pressure valve interposed between the outlet port and said areas, said valve being so oriented as to permit flow only in the direction of said outlet port.

4. In a vane type pump having inlet and outlet ports, the combination of: a rotor; a plurality of slots in said rotor; a vane slidable in each of said slots; a vane track having a pair of suction and a pair of pressure ramps; separate surfaces providing large and small areas mechanically associated with each vane, said areas being so oriented as to be effective under pressure to urge the vanes against the track; a first passage for effecting common fluid communication between the large area of a vane traversing one of said pressure ramps and the small area of a vane traversing one of said suction ramps; a second passage for effecting common fluid communication between the large area of a vane traversing the other of said pressure ramps and the small area of a vane traversing the other of said suction ramps; and separate means associated with each of said first and second passages, for maintaining the pressure on said large and small areas a predetermined amount above outlet pressure during the period of common communication.

5. In a vane type pump having inlet and outlet ports, the combination of: a rotor; a plurality of slots in said rotor; a vane slidable in each of said slots; a vane track having a pair of suction and a pair of pressure ramps; separate surfaces providing large and small areas mechanically associated with each vane, said areas being so oriented as to be effective under pressure to urge the vanes against the track; a first passage for efiecting common fluid communication between the outlet port, the large area of a vane traversing one of said pressure ramps, and the small area of a vane traversing one of said suction ramps; a second passage for effecting common fluid communication between the outlet port, the large area of a vane traversing the other of said pressure ramps, and the small area of a vane traversing the other of said suction ramps; and separate means associated with each of said first and second passages, for maintaining the pressure on said large and small areas a predetermined amount above outlet pressure during the period of common communication, each of said separate means comprising a one-Way, back pressure valve interposed between the outlet port and said areas, said valve being so oriented as to permit flow only in the direction of said outlet port.

References Cited in the file of this patent UNITED STATES PATENTS 2,641,195 Ferris June 9, 1953 2,820,417 Adams et al. Jan. 21, 1958 2,832,293 Adams et al. Apr. 29, 1958 FOREIGN PATENTS 152,123 Sweden Oct. 25, 1955 668,979 =France July 27, 1929

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