US2884865A - Power transmission - Google Patents

Description

' May 5,1959 R. B. PETTIBONE 4,

' POWER TRANSMISSiON Filed June 7, 1954 FIG. 4

INVENTOR. RAYMOND B. PETTI BON E ATTORNEY United States Patent POWER TRANSMISSION Raymond B. Pettibone, Detroit, Mich., ers Incorporated, Detroit, Mich., Michigan assignor to Vicka corporation of This invention relates to 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 specifically this invention relates to sliding vane type devices for use in such a transmission.

One of the most widely used types of fluid pressure energy translating devices is that in which a rotary member carries a plurality of vanes which are slidable therein to abut a track having portions at varying distances from the rotor. When the ends of the vanes are kept in abutment with the track, the space between adjacent vanes varies cyclically as the rotor turns, resulting in a pumping action. These units have met with wide acceptance because of their low and initial cost and the long service life resulting from automatic wear take-up which isinherent in the design.

The most common of the vane type devices are those in which the vanes slide radially in and out in the rotor. During operation of such a device the vanes are urged outward by centrifugal force and are urged inward by mechanical cam action of the track. Additional inward force on the vanes is developed by the cyclic exertion of operating pressure of the device over some part, or all, of the area of the outer ends of the vanes. To prevent inward collapse of the vanes it is necessary to supplement centrifugal force by the application of a balancing pressure to the underside of the vanes.

Some prior devices have applied the discharge pressure of the unit to the underside of each of the vanes throughout the complete cycle of operation. This method is in wide use although it is subject to the disadvantage that during that part of a cycle when a particular vane has its outer end subjected only to low pressure, the resulting outward unbalance on the vane causes rapid wear of the vane track in that region.

Because of the above noted disadvantage of the system utilizing continuous high undervane pressure, another system in wide use is one in which a plurality of under-vane ports are provided to subject the underside of each vane to outlet pressure whenever the outer end is subjected to high pressure, and to connect the underside of the vane and the low pressure port of the device when only low pressure is imposed on the outer end of the vane.

The recent wide acceptance of hydraulically actuated accessories for motor vehicles has pointed up some inadequacies of prior devices. The hydraulic pump installation on many motor vehicles is such that the operating speed of the pump during highway operation of the motor vehicle may be as high as 12,000 revolutions per minute. It has been found that conventional pumping mechanism suffers a significant loss in volumetric efficiency at such high speeds and, more important, suffers a marked reduction in pressure producing ability.

These losses probably result from separation between the vane track and the yanesat high speeds, even though in the radially sliding vane type the centrifugal force tending to keep the vane in contact with the track is greatly increased. The probable explanation for this seeming paradox is that at extremely high rotor speeds,

the pressure differential required to push the fluid out of intervane spaces and into the delivery passage becomes so high that the vanes are unbalanced inwardly and move away from the track.

It is an object of this invention to provide an improved, low cost fluid pressure energy translating device of the vane type.

More specifically it is an object to provide such a device having an improved vane biasing arrangement in which wear is minimized and efliciency is increased.

It is a further object to provide a vane biasing arrangement in which the magnitude of undervane pressure is related to the pressure on the outer ends of the vanes and exceeds that pressure by a predetermined amount, thus assuring continuous contact between the outer end of the vane and the track.

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 sectional view of a device embodying the present invention and taken on line 1--1 of Figure 2.

Figure 2 is a partial section taken on line 22 of Figure 1.

Figure 3 is a section taken on line 3-3 of Figure 1 and illustrates the device schematically connected into an operating circuit.

Figure 4 is a partial section taken on Figure 2.

Referring first to Figure 1, the device includes a body 10, a ring 12, and a head 14. Body 10, ring 12, and head 14 are secured together in a sandwich relation by a plurality of bolts 16. An O-ring seal 18 prevents leakage between the body 10 and the ring 12 at their juncture. The head 14 includes an elongation 20 which extends outward to provide a mount for a cylindrical tank, or reservoir 22, which is telescoped over the head 14 to engage the ring 12. A seal 24 prevents leakage from the reservoir at its junction with ring 12, and the tank is secured in position by a bolt 26. The tank 22 is provided with a combination filler cap and dip stick 28.

Ring 12 has therein a general elliptical cam, or track 30. A rotor 32 having substantially the same axial thickness as ring 12 is positioned within the track 30. The rotor 32 has a plurality of radial slots, in each of which a vane 34 is radially slidable to engage the track 30. The rotor 32 is supported for rotary movement within the track 30 by a drive shaft 36. Shaft 36 extends from the body 10 for engagement with a prime mover not shown and is encircled by a conventional seal 38. Seal 38 prevents leakage from the body 10 at the point of egress of the shaft 36. Referring to Figure 2, the dotted outlines of the track, rotor, and vanes, therein illustrated, indicate merely positional relations and are not hidden edge lines.

The body 10 includes a fiat plane face 40 which axially abuts the rotor 32 and the vanes 34 in fluid sealing engagement. Head member 14 has a bore 42 therein in which a pressure plate 44 is axially slidable. The pressure plate 44 coacts with the bore 42 to form a pressure chamber 46, the pressure in which urges pressure plate 44 toward the rotor 32. A flat plane face 48 on the pressure plate 44 axially abuts rotor 32 and vanes 34 in fluid sealing engagement. A spring 50 provides an initial biasing force to urge the pressure plate 44 toward line 4-4 of Patented May 5, 1959..

the rotor 32 until pressure is built-up in the chamber 46. The space between each pair of adjacent vanes thus forms a working chamber which undergoes cyclic expansion and. contraction. during rotation of the rotor. Assumi'ng the direction of rotor 32 to be counter-clockwise as viewed in Figure 3, the working chambers in the general' areas 52' will be contracting and thus discharging fluid while those in the areas 54 will be expanding and hence taking in fluid. A pair of outlet ports 56' which extend completely through the pressure plate 44 overlie the discharge zones 52. Similarly, a pair of outwardly trenched inlet ports 58, in the pressure plate 44, overlie the inlet zones 54. A pair of openings 60 extend from the interior of tank 22 through the ring 12 to communicate with a pair of auxiliary inlet ports 62 in the body member 10. Auxiliary ports 62 are provided to permit easier filling of. the working chambers during high speed operation. Inlet ports 58 and 62 are thus in unrestricted communication with the interior of the reservoir 22.

The fluid displaced by the pumping mechanism passes through the delivery ports 56 and into the pressure chamber 46 where it acts to urge the pressure plate 44 toward. the rotor 32. From the pressure chamber 46, the discharged fluid passes into a delivery passage 64 in the head 14. A pair of passages 66 and 68 in the ring 12 and body respectively, are coincident with passage 64 at the juncture of those parts. A transverse drilled passage 70 intersects the passage 68 and extends to an external delivery connection port 72 in a boss 74 on the body member 10. An external return connection port 76, in a boss 78 on the head 10, communicates with a drilled passage 80 which extends into the body member 10. An extension 82 of passage 80 intersects the shaft bore. 84 at. a point interior of the shaft seal 38. An axial drilled; passage 86 intersects. passage 80. and aligrm with passages 88 and 90 in the ring 12 and. headv 14, respectively, to communicate with the interior of. tank 22. Communication between the passage 88 and the passage. 9.0. is. controlled. by a. check valve 92, as can. be seen in Figure 4, which is biased to. the closed position by aspring 9.4, for apurpose to be hereinafter described.

In Figure 3 the pumping mechanism isv illustrated as being connected in a typical circuit. A delivery conduit 96. extends from. the delivery connection port 72 to the inlet port 98 of a steering booster. 100. Booster 100 may be of the type described in the patent to Vickers, No. 2,022,698 and is fixed to the frame of a motor vehicle. at 102, connected to the vehicle steering linkage by a rod104 and controlled by a pitman arm 10.6. The booster outlet. port 108 is connected by a conduit 110 to the return connection. port. 76. of. the pumping mechanism. The. control valveof booster 100 is. of the conventional open center type, thus flow in. the return. conduit 11.0. is continuous and substantially constant.

Thevane track 30 includes an inlet ramp which extends from a to b, a true arc portion which extends from "b to c, a discharge ramp extending from c to d, and another true arc portion extending from d to e. The track is symmetrical about both its major and minor axes, thus each of the ramp and true are portions from a to e are duplicated in the lower portion of the track. As. the ends of the vanes traverse the inlet ramps, the vanes move radially outward with respect to the rotor and while the vane ends traverse the discharge ramps, the. vanes now move. radially inward. As the.- vane; ends traverse the true are portions; the. vanes. partake of no radialmovement.

The inner ends of. thevane slots areenlarged to form, with the inner ends; of. the;vanes,. small undervane, pres.- sure. chambers 111 which. undergo. cyclic contraction and expansion. during rotation. of the. rotor 32. A pair of high. pressure undervane. ports 112 are trenched into the faceof pressure plate. 44. and are so positioned. as to communicate with eachundervane pressure chamber while its associated vane moves across the major diameter true arc sections of the track, the discharge ramps, and the minor diameter true arc sections. A pair of low pressure undervane ports 114 are provided which communicate with each undervane pressure chamber during the time the vane associated with that chamber moves outwardly along the inlet ramps of the track. The volumetric changes in the undervane chambers thus contribute to the overall pumping capacity of the unit, as well as insuring a positive outward bias of the vanes as hereinafter described.

Each of the ports 112 communicates with the pressure chamber 46 through a small drilled passage 116. A spring biased. check valve 118 is positioned in each of the passages 116 and serves to block communication between each port 112 and the pressure chamber 46 until the pressure in ports 112 exceeds the pressure in chamber 46 by an amount dependent on the biasing force of the check valve springs.

The pressure plate 44 has a central recess 120 therein, which is aligned with the drive shaft 36. Recess 120 communicates through a pair of trenched channels 122 with the low pressure undervane ports 114. The recess 120 communicates. through the clearance spaces between the teeth of the shaft-to-rotor spline connection with the shaft bore 84 in the body member 10. As was heretofore noted, the shaft bore 84 is in communication with the return port 76 through the drilled passage 82. Since the fluid entering the return port 76 must pass through the spring biased check valve 92 to reach the reservoir, the pressure ahead of check valve 92 will be established by the strength of spring 94. As can be seen from the foregoing, the back pressure in the return passage produced by the valve 92 will also exist in the low pressure undervane ports 114. As any particular vane moves along an inlet ramp, the undervane pressure chamber associated therewith will thus be subjected to a pressure, the magnitude of which is determined by the strength of the spring 94 of the check valve 92.

As a particular vane moves over the true are portion of" the track b-c, over' the discharge ramp cd, and over the true arc portion de, the pressure in its associated undervane chamber will exceed the pressure in the pressure chamber 46 by an amount controlled by the strength of the spring of the check valve 118. This is true because the chambers beneath the vanes which contact the track in the section b-c and de" are undergoing no volumetric change, while those beneath the vanes contracting the discharge ramp c-d are contracting in size. The fluid displaced by the net volumetric change of all the undervane chambers in communication with either high pressure undervane port 112 must pass through one of the check valves 118 to the pressure chamber 46.

In an actual unit, highly successful operation has been obtained where the springs of check valves 118 were so selected as to produce approximately a 50 pound per square inch pressure diflerential between the ports 112 and the pressure chamber 46, and where the spring 94 of valve 92 was selected to maintain a back pressure of approximately 50 pounds per square inch in the ports 114. The pressure values cited are merely exemplary and may be selected for most eflicient operation of any particular unit.

Pumping units embodying the invention disclosed herein have been successfully operated at much higher speeds than those at which conventional units are capable of functioning. This improved performance is a result of the-provision of'pumping structure in which the magnitude ofthe'undervane pressure-is related to the pressure on the outer ends of the vanesand' exceeds that pressure by a predetermined amount. The vanes are always maintained in positively induced contact with the track at all times, yet-wear is minimized by avoiding. excess outward pressure unbalance.

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 fluid pressure energy translating device of the radially sliding vane type wherein the outer end of each vane abuts a track member: discharge and inlet passages for said device; a slotted rotor carrying said vanes; means in said device forming a pressure chamber communicating with said discharge passage, said means including a pressure plate biased into axial fluid sealing engagement with said vanes and rotor by pressure in said chamber; passage means for conducting the delivery pressure of said device to said pressure chamber; means forming an undervane pressure chamber at the inner end of each vane to urge each vane into abutment with said track member; supply means for conducting fluid to said undervane chamber; port means in said pressure plate to communicate with each undervane chamber while its associated vane moves in a direction such as to displace fluid from that undervane chamber; and means forming a flow restricting path from said port means, through said pressure plate, to said pressure chamber whereby back pressure is built-up in said undervane chambers to maintain abutment between each vane and said track member.

2. In a fluid pressure energy translating device of the radially sliding vane type wherein the outer end of each vane abuts a track member: discharge and inlet passages for said device; a slotted rotor carrying said vanes; means in said device forming a pressure chamber communicating with said discharge passage, said means including a pressure plate biased into axial fluid sealing engagement with said vanes and rotor by pressure in said chamber; passage means extending through said pressure plate for conducting fluid delivered by said device to said pressure chamber; means forming an undervane pressure chamber at the inner end of each vane to urge each vane into abutment with said track member; supply means for conducting fluid to said undervane chambers; port means in said pressure plate to communicate with each undervane chamber while its associated vane moves in a direction such as to displace fluid from that undervane chamber; and means forming a flow restricting path from said port means through said pressure plate to said pressure chamber whereby back pressure is built-up in said undervane chambers to maintain abutment between each vane and said track member.

3. In a fluid pressure energy translating device of the radially sliding vane type wherein the outer end of each vane abuts a track member: discharge and inlet passages for said device; a slotted rotor carrying said vanes; means in said device forming a pressure chamber communicating with said discharge passage, said means including a pressure plate biased into axial fluid sealing engagement with said vanes and rotor by pressure in said chamber; passage means for conducting the delivery pressure of said device to said pressure chamber; means forming an undervane pressure chamber at the inner end of each vane to urge each vane into abutment with said track member; supply means for conducting fluid to said undervane chambers; port means in said pressure plate to communicate with each undervane chamber while its associated vane moves in a direction such as to displace fluid from that undervane chamber; means forming a fluid passage leading from said port means through said pressure plate to said pressure chamber; and valve means resiliently biased to block said passage, said valve means being operable in response to pressure in said port means to open said passage, whereby back pressure is built-up in said undervane chambers to maintain abutment between each vane and said track member.

4. In a fluid pressure energy translating device of the radially sliding vane type wherein the outer end of each vane abuts a track member: discharge and inlet passages for said device; a slotted rotor carrying said vanes; means in said device forming a pressure chamber communicating with said discharge passage, said means including a pressure plate biased into axial fluid sealing engagement with said vanes and rotor by pressure in said chamber; passage means for conducting the delivery pressure of said device to said pressure chamber; means forming an undervane pressure chamber at the inner end of each vane to urge each vane into abutment with said track member; supply means for conducting fluid to said undervane chamber; port means in said pressure plate to communicate with each undervane chamber while its associated vane moves in a direction such as to displace fluid from that undervane chamber; means forming a fluid passage leading from said port means through said pressure plate to said pressure chamber; and check valve means to block said fluid passage, said check valve being responsive to a predetermined pressure difierential between said port and said pressure chamber to open said fluid passage, whereby back pressure is built-up in said pressure chambers to maintain abutment between each vane and said track member.

5. In a fluid pressure energy translating device of the sliding vane type wherein one end of each vane abuts a track member: outlet and return passage means associated with said device; means forming an undervane pressure chamber at the end of each vane opposite said one end; an area on each vane exposed to pressure in its associated undervane pressure chamber to urge that vane into abutment with said track member; means in said device forming a discharge pressure chamber, said means including a pressure plate biased into axial fluid sealing engagement with said vanes by pressure in said discharge pressure chamber; port means to communicate with each undervane pressure chamber while its associated vane moves in a direction such as to increase the size of that undervane pressure chamber; port means to communicate with each undervane pressure chamber while its associated vane moves in a direction such as to displace fluid from that undervane pressure chamber; means in said return passage forming a restriction to flow therein; means forming a first fluid passage interconnecting said first named port and said return passage at a point upstream of said restriction; means forming a second fluid passage in said pressure plate interconnecting said last named port means and said discharge pressure chamber; and means in said second fluid passage forming a restriction to flow therein, whereby back pressure is built-up in said undervane pressure chambers to maintain abutment between each vane and said track member.

References Cited in the file of this patent UNITED STATES PATENTS 2,255,781 Kendrick Sept. 16, 1941 2,319,238 Kendrick May 18, 1943 2,387,761 Kendrick Oct. 30, 1945 2,487,721 Minshall Nov. 8, 1949 2,538,194 Ferris Ian. 16, 1951 2,630,681 Ferris Mar. 10, 1953 2,631,540 Baugh et a1. Mar. 17, 1953 2,632,398 Ferris Mar. 24, 1953 2,641,195 Ferris June 9, 1953 2,653,550 Gardiner et al. Sept. 29, 1953 2,670,689 Ferris Mar. 2, 1954 FOREIGN PATENTS 433,488 Great Britain Aug. 15, 1935 440,479 Great Britain Dec. 27, 1935 1,048,619 France Aug. 5. 1953

Images