Dec. 117, 1946. J. ROBINSON 2,412,835 : POWER TRANSMISSION Filed Nov‘. 29,‘ 1940 30 26 E4 64 40 4a 4a 3a 22 ' INVENTOR ‘JAMES ROBINSON ZZZ/(.4 ATTORNEY Patented Dec. 17,1946 , ‘2,412,835 » UNITED STATES '‘ PATENT OFFICE vrowan pgz?ihssrtis James Robinson, Detroit, Mich; assignor Vickers Incorporated, Detroit, Mioh._, _a corpo ration of Michigan Application November 29, 1940, seem No. scares 1 ' 50laims. (oi. 103-162)‘ _ ‘This invention relates to power transmissions, particularly to’ those of the type comprising two 2 I venting seepage of air'into . the working circui - of a wet casing type pump. , I . or more ?uid pressure energy translating devices, A further object is to Provide an improved one of which may function as a pump and an ' means and method for initially ?lling the casing other as a ?uid motor. of a pump of this character. The invention is more particularly concerned’ _ Further objects and advantages of the present with a fluid pressure energy translating device ‘ invention will be apparent from the. following adapted to function as a pump or motor in an description, reference being had to the accom open-circuit type of power transmission system and particularly suited for high speed operation. In'systems of‘ this character, particularly those of smaller size, which are capable of operating at panying drawing wherein a preferred form of the present invention is clearly shown. _ ' In the drawing: I Figure l is a longitudinal sectional view of ‘a speeds of several thousand revolutions per min wet case pump embodying a preferred form of ute, considerable trouble has been encountered the present invention. with air‘ getting into the working circuit and the 15, ' Figure 2 is a fragmentary sectional view taken well-knownv attendant di?iculties arising when on linev 2-2 of Figure 1 and showing diagram this occurs. The term “pump” is used hereafter matically a conventional open-circuit type of inthe speci?cation and claims as embracing both power transmission system in which the pump is ' a pump and a ?uid motor. _ . " connected. . Pumps of the typehaving a. wet case, that is, 20 Referring now to Figure'l, the pump com one which is normally ?lled with substantially prises two tubular casing members it and i2 dis ' idle power transmission liquid, utilize the casing posed at an angle relative to one another, ‘the , as a means-for collecting the ?uid leaking past member‘ I 0 carrying anti-friction bearings II on the piston and valve mechanism and for return which a ?anged drive shaft It is mounted. An ing it to the expansion tank provided in the cus oil seal l8 closes the righthand end of the casing tomary open-circuit system. It is frequently de It. The shaft. I6 is adapted to be driven by the , sirable to locate the pump-at a considerable dis I tance from the expansion tank as, for example,‘ aboard aircraft where the pump may be located shaft of a suitable primemover indicated at 20 and which is spline-connected to the ?anged shaft II." I ' " - at ‘a wing-mounted engine of the plane and the so The righthand end of the shaft It carries a expansion tank positioned at some convenient re ?ange 22 which is provided with a plurality of mote place in the fuselage. In such cases it is un . desirable to run a separate casing drain line he ball Joints 24 by which piston rods 26 are articu lated to the ?ange 22. At their opposite ends the ‘ tween the casing and the ‘expansion tank so that piston rods 26 carry ball-Jointed pistons 28 recip resort‘is had‘ to usingithe pump suction line for 35 rocable in cylinder bores 80. The latter are both feeding the inlet of the pump and for receiv formed in a cylinder barrel 32 which is jour ing excess leakage ?uid from the pump casing. nalied on an anti-friction bearing 34 carried by a Where systems of this character are operated hollow stub shaft 88." The-latter to a at high speed, as they‘usually are in aircraft; in M ‘valve .plate block 38 which in turnisissecured secured to stallations, considerable di?lculty, has~been ex 40 the open end of easing member If. A Cardan perienced in keeping air out of the working cir shaft 40, having universal joints 4! at its op cuit. ,' Applicant has found that with systems of posite ends, connects the cylinder barrel 32 to the this character it occasionally happens that, due to the resistance of the pump suction line, the - shaft it for conjoint rotation therewith. - ‘ ‘ The valve plate is provided with-the usual an- ' pressure therein is reduced below atmospheric by 45. nuiar valving surface it having a pair of arcuate 1 the high speed operation of the pump, and as a consequence the interior of the Dump' casing is ' correspondingly subjected to negative pressure. . ports 46 and 48 formed therein and communi eating with pressure and suction-connections Il' and 82. ,The Cardan shaft 40 is urged to the left , This premits air to badrawn into the pump cas a spherical abutment block It by. a ing through the oil seal at‘the shaft, and since 50 against spring-pressed abutment block it at its right the casing is connected to the pump, suction line, end.‘ The cylinder_ barrel" is urged into such air is eventually delivered to the working : handv contact with the‘ valve plate 38 by a spring 58I circuit or the pump. ' y . which is positioned between ‘the bearing 34 and ' 1 It is an object of the present invention to pro shoulder ‘I at the lefthand side of the block 32. vide an improved means and method for pre 'For the purpose of preventing drawing in of air I 2,419,830 on, the leakage liquid will begin ?owing through to the interior of the pump casing there is pro the outlet path and continue so to ?ow as long as vided an outlet path for the leakage oil which is ' constantly being fed into the interior of the eas ing at a slow rate by leakage between the valve . the pump keeps operating. valve ‘l0, anynegative pressure created in suc tion port 62 by high speed operation and by the resistance of conduit 82 can never reach the in - teriorof the casing l2 so that, in order for oil to escape from the casing, it must build up ‘a pressure su?lcient to overcome relief valve ‘Hi. This pr'essure'is, of course, builtnp by the con 64 in the Cardan shaft 48. This passage in turn ' communicates with a passage 68 in the block 84 which communicates with the hollow interior of tinuing ?ow ofleakage oil into the casing which, stub shaft 86. The latter is also provided with though small, is nevertheless incessant and re quires a path for escape-‘or it will buildup tre cross bores 68 which receive leakage ?owing radi- : ally inward across the pressure surface’ 44 of the ' a ' < ' - Due to the back pressure maintained by relief plate and cylinder barrel as well as leakage past the piston 28. The outlet provided for this oil comprises a cross bore~62 formed in the block 88 and communicating with a longitudinal passage valve plate 88. _, mendous pressure. In this manner the pressure I in the casing will be maintained slightly positive or above atmospheric so that the pressure on the lightspring 12. The spring abutment block 14 f lefthand side of oil seal I8 is always above that on the righthand side. This insures that no air andv the stub shaft 86 are locked to the valve ' will be drawn in through the seal and that a plate 88 by a pin 16 which is accessible by a pipe small seepage will take place through the seal plug 18.‘ The relief valve 18‘ discharges through suilicient to keep thelatter lubricated and pre an angular cross bore 88 which communicates vent its burning at the high speeds of operation with the suction port 52. Y ' Mounted in the lefthand end of the hollow stub shaft 36 is a relief valve ‘III which is backed by a customarily encountered. . The pump described may be connected in the. ' ' While the form of embodiment of the invention usual open-circuit hydraulic ‘power transmission 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 system as illustrated in Figure 2. Thus the suc tion port 52 is connected by a suction conduit 82 . with the usual expansion tank 84. The ‘delivery claims which follow. ' connection 68 connects by means of a conduit 88 having a ?lling and air-bleed valve 88 at a high 30 point therein with the pressure port of a con ventional four-way valve 98. The latter has its _ What is claimed is‘ as follows: 1. In a reciprocating piston pump of the type having a sealed casing of ?xed liquid volume and having separate suction and delivery portsthe tank port connected by a conduit 92 with the combination of means forming a connection be tank 84 and its cylinder ports connected by con duits 84 and 86 with the opposite ends of a ?uid 35 tween the casing and the suction port of the pump and constituting the'sole exit from the eas ing and a pressureresponsive valve in said con nection adapted to con?ne all leakage ?uid to with oil in the‘ customary manner through the the casing until a predetermined positive pres valve 88 after which the pump may be placed in operation withdrawing oil from the tank 84 40 sure is reached in the casing, said connection leading from a point near the center of revolu through the suction conduit 82 and delivering ‘it’ tion of the pump parts whereby all air originally from delivery port 58 through pressure conduit motor 98. . ‘In operation,‘ the working circuit may be ?lled present in the casing will be discharged from the‘ 88. r customarily the valve 88 is left in neutral delivery port duringvinitial operation of the ‘position in which the pump is bypassed, and . the pump is operated for some time until-the air 45 pump. 2. In a reciprocating piston‘ pump of the type ' has been completely removed from the system as having a sealed casing of ?xed liquid volume and evidenced by the inability to bleed air from the pressure line 86' when valve 88 is cracked open. ' During this operationv of the pump, any air origi- I nally present inthe pump‘ casing will be trans ferred to the working circuit in the following manner: " 50 bination of an outlet constituting the sole exit ' As leakage occurs from the working circuit to the interior of thefcasing, the body of liquid is gradually built up therein which at ?rst, by its , mere presence in the casing, tends to displacelair out through the outlet path beginning at the pas sage 62 until the relief valve 10 is reached. ‘ As having separate suction and delivery ports and rotating working parts disposed within and dis charging leakage ?uid into the casing the com from said casing and communicating with‘said suction port and a pressure responsive valve in said outlet for maintaining a slight positive pres sure in said casing. 3. In a reciprocating piston pump of the type having a sealed casing of ?xed liquid volume and having separate suction and delivery ports and more and more liquid ‘enters the casing, this a rotary cylinder barrel journalled on a hollow It will be seen that noliquid can escapethrough having a sealed casing of ?xed liquid volume and pin mounted on‘ a wall of saidcasing, the com liquid will-be churned around by the revolving bination of means forming a connection between parts setting up a centrifugal action keeping the the casing and,’ the suction port of the pump and .liquid in the‘ radially outermost portion of the ' including said hollow pin as a part thereof and casing and pocketing any air present in the cen a pressure responsive valve in said hollow pin traP portion of the casing. As the liquid con, tinues to enter the casing, the pressure builds up 65 adapted to con?ne all leakage ?uid to the casing until a predetermined positive’ pressure is reached until the relief valve 10 opens, at which time a in the casing. ’ _ small ?ow takes place continuously through the 4. In a reciprocating piston pump of the type relief valve and passage 88 to the suction port 52. this path until all the vair in the casing has‘been 70 having separate suction and ‘delivery ports and having a rotary cylinder barrel provided with a displaced since; due to the different densities of plurality of axially disposed cylinder bores dis the liquid and the air, the centrifugal force will , maintain the liquid in the outer part of the eas ' posed within and discharging leakage ?uid into the casing, the combination of an outlet consti through the outlet passage 62. From this point 76 tuting the sole exit from said casing and com _ ing until all ’of ,theair. has been forced out’ 2,412,885 . 6 ' municating with said suction port and a pressure said casing and communicating with said suc responsive valve in said outlet for maintaining a tion port and a pressure responsive valve in said slight positive pressure in said casing. outlet for maintaining a slight positive pressure 5. In a reciprocating piston pump of the type in said casing. Said outlet leading from a point having a sealed casing of fixed liquid volume and 5 adjacent the center of rotation of the barrel having separate suction and delivery ports and whereby any air present in the casing is forced having a rotary cylinder barrel provided with a to said outlet by centrifugal force in conjunction plurality of axially disposed cylinder bores dis posed within and discharging leakage ?uid into the casing, the combination of a single outlet from 10 with the pressure built up by the leakage ?uid against said valve. -- > , JAMES RQBINSON.