US2370710A - Hydraulic pump and transmission - Google Patents

Description

March 6, 1945. L.. c. BLAIR HYDRAULIC PUMP AND TRANSMISSION 4 Sheets-Sheet l Fil ed Aug. 27, 1942 Lyman@ 'J5/air Fil'ed Aug. 27, 1942 4 Sheets-Sheet 2- Decke-ASE ENG/us nfs/1. ARROW-bi 71) Nans/43E ENG/NE ARM. ARROW-CL 9. 0 ,1 .w 6 M @65 m5 HHH j 6 .a 4 1 4 .Mx 1 1 2 e 4 www March 6, 1945. L. c BLAlR 2,370,710

HYDRAULIC PUMP AND TRANSMISSION Filed Aug. 27. 1942 4 Smets-sheet s fullllmlnm v1 Innnnu` Y Lyman C'. .Bla/'r Bum/nap March 6, 1945. l l.. c BLAIR A HYISRAULIC `PUMP AND TRANSMISSION Filed Aug. .27, 1942 4 sheets-:sheet 4 :www

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reame Maf. s, 194s UNITED s'rA'rE s PA'r-EN This invention relates to hydraulic pumps and hydraulic transmissions and morev particularly to such pumps and transmissions as are adapted for lhe transmitting of power from internal coml bustion engines to-the driving elements, such as the wheels, of automobiles, trucks, railway rolling stock and the like.

vOne object of the invention is to provide a hydraulic transmission mechanism including a pump and associated controls of improved and simplified construction and whichV cooperate to provide stepless changes in the relative speeds of the pump and hydraulic motor driven thereby;

AnotherV object is to provide a transmission mechanism of the character referred to in which the prime mover, e. g. internal combustion engine driving the pump, may be .operated at a selected substantially constant speed, which should be the speed at which the engine operates most emciently, and to automatically vary the ratio of engine speed to hydraulic motor speed to suit varying load conditions.

Another object is to provide a novel and improved governor control for a transmission' mechanism of the kind referred'to. I

A further-object is to provide control means for reducing |-the torque reaction on the engine in the'eve'nt of av quick opening of the engine throttle valve so as to minimize or eliminate l A knocking such as otherwise would be apt to occur under such conditions.

Other objects will becomeapparent v:from a reading of the following description, ythe appended claims, in which: v l

Figure l is a somewhat diagrammatic plan viewV showing portions of a motorl vehicle equipped with hydraulic transmission embodyand the accompanying drawings,

ing the invention Figure. 2 is a fragmentary sectional view ofa y pump and .control mechanism embodyingthe invention;. Figure 3' is a detail v showing a pulsationdampening chamber;

Figure 4 is a fragmentary section on the `line view in vertical section bearing lz. Fast to and rotataplewitn the ,m1-.orA

-` Figure 5 is a fragmentary vertical section' through '-a control motor ciatedparts; t

Figure-6 isa fragmentary view 'looking in the direction of the arrow X in parts, shownin section:

embodiment of the invention'z' amature and asso- Figure 2with some j. Figure' '1 is a fragmentaryview ,or a mqdmea and transmission are shown as being designed for drivingA a vehicle but it will be understood that it is not intended to indicate that the invention is limited to. application-in connection with vehicles alone. f

Figure 1 showssomewhat diagrammatically a hydraulic transmission embodying the invention in connection with a vehicle including an internal combustion engine prime mover A and .l a rear axle and wheel assembly B. The engine isv shown as including an intake manifold or pipe l and drive shaft 2. The rear axle assembly B includes the usual drive shaft 3, differential gearing 4 and driving wheels 6 5. The hydraulic transmissionfor delivering power from the engine shaft 2 to the wheels 5 includesva pump or motor- D arranged to be supplied with workthrough suitable scribed.

In .its-more detailed nature pipes Vor conduits tof'be de-L ythe pumpV C is shown as including two cylinders 6-6 sta? tionarily mounted on brackets 1-1 with their axes' radial to the shaft-i3. It will be under- -stood thatlany desired number of radially disposed cylinders may be employed, although as a general rule a plurality of cylinders `-is desir- 'I is ahollow shaft I3 journaled-at its ende rev mote from the rotor-9 infabearing |41 A gear l I5 secured to thehollow shaft I3 meshes' with al so gear I6 rotatable with the engine shaft ,2, the.

is dven by power supplied by the engine shaft.' v

arrangement being such that the rotor 9 f Connections are provided between the rotor l and the pistons 8 for reciprocating the -latter consequent vupon rotationofvthe [rotor 8, the ar-' generally designated C and a hydraulic turbine ing uid under `pressure delivered by a pumpC ame in tne'mterest of smooth fluid deliveryfwith i l' l v vided rangement being such that magnitude of piston strokes can be varied so as to controlthe pump output in a. manner to maintain the speed of the engine A substantially constant at its optimum value, for example, at 2500 R. P. M. or at or near a value selected by the vehicle operator. The 'driving connections interposed between the rotor 9 and pistons 8 include a crosshead guide l1. preferably formed integrally with the y wheel I0, a crosshead I8 slidable onthe guide l1 and carrying a crosshead pin I9, and a connecting rod 28 interposed between the pin I8 and the piston 8 shown at the top of Figure '2. The connecting rod 20 is formed .with

a clevisv 2l jointed to a connecting rod 22 `by a knuckle pin 23. the rod 22 in turn being connected Ain. the usual manner to the piston 8V shown at the bottom in Figure 2. During rotation of the rotor S'with the pin I9 positioned eccentrically of. the axis of rotation, the pistons 8 will be reciprocated in their associated cylinders 8, the length of their strokes being dependentupon the degree of eccentricity of the crosshead pin I8.

Each cylinder is provided at its outer end with an intake valve 24 adapted to control the admission of fluid through a pipe line 25 leading to a reservoir 28 equipped with a breather cap 28a. For controlling the delivery of fluid under pressure fromthe cylinders, the latter-are provided with discharge valves *21 adapted to open during the outward str kes ofthe pistons 8 to permit pressure uid ow through delivery pipes 28 into a thermally insulated pulsation dampening chamber 29 and thence through a pipe 30 and reversing valve 30* to the turbine or uicl motor D coupled as aforesaid to the shaft 3 of 'the rear end assembly B, the shaft 3 constituting the driven element to which the hydraulic transmission delivers power. Fluid which is passedthrough the turbine or motor D flows through a return pipe 32 and the reversing valve 30* to the receiver 28, thus completingthe fluid circuit. In order to prevent the building up of excessive or unsafe pressures `a relief 'conduit 38 interposed between the high pressure conduit notform .part of the present invention andany thereby move the crosshead land crosshead pin i i9 to an eccentric position such that rotation of the crosshead pin will reciprocate the pistons 8 inthe pump cylinders 8. Inasrnuch as the pump pistons 8 are working against pressure there will be back pressure exerted through the piston rods 2D and 22 tending to move .the crosshead pin I9 to a concentric position. However, proper positioning of the piston 48 acting in opposition to the back pressure exerted through the piston rods 20 and 22 will maintain the crosshead pin in the desired eccentric position.

Power for moving the, piston 40 for positioning the crosshead pin I9 is supplied by-'an electric motor 42 operated under the control of a governor generally designated 43. 'The motor 42 includes an armature 44 (see Figure 5) carried by a core or sleeve 45 which is internally threaded to mesh with the exterior threading on a supportingscrew 48 mounted on bearing brackets 41. Thrust bearings 48 are interposed between the ends of the armature sleeve 45 and the brackets 41 for holding the sleeve 45 against movement axially with respect to the screw 48. LAy slot 49 extending along the screw 46 receives tongues 50 extending inwardly from` the bearing .brackets The arrangement is such .that when the armature sleeve 45 is rotated, it is prevented by the bearings 48 and brackets 41 from moving axially and consequently the screw and tongue 50 will be moved longitudinally.

l Longitudinal movement of the screw in the direction of the arrow b in Figure 2 transmits thrust through a bearing 5i to al rod 40 connected to the piston 40 so as to move the latter in the direction of the arrow b and thus shift the crosshead pin I9 away from the axis of the shaft I3 in the manner previously described.

In accordance with a further feature of the invention, mechanism of the kind thus far described may be equipped with governing means for maintaining the speed of the engine A` substantially v'constant at a selected value.

accomplished by automatically increasing the Preferably this is rate of pump discharge in response to an increase 5.0 in response to a decrease in engine speed, thus reducing the torque and causing the engine'to fone of a number, o fwell known hydraulic mo- D includes control. l

rs 35 adapted toAoperate deilectin'g vanes (not tors or turbines may be employed. The turbine .s .As has been indicated hereinabove, the eeeni' tricity of the crosshead pin i9 determines the rate of discharge of thel pump C. In accordance 'with the invention, mechanism. is provided for changingthe eccentricity ofthe pin I9 in respouse tordeviations in the engine speed. The

j hepdpimpositioning cylinder 88 formed inte- -hollow shaft Il which latter constitutes a servo in'engine speed, thusK increasing the torque re action on the engine to slow it down, and con- `versely by decreasing the rate of pump discharge speedup. Y As shown in Figures 1 and 2, a gear 52 meshing `with the engine driven gear I8 is fast with a -is iastwith a governor yoke journalecil in. a

governor casing 58. The governor yoke mounts i ily weights 51 which are urged to their' inner po- `lvsitions as shown in Figure 2 by means of a spring 58 interposed between a thrust bearing 58 overlying theily .weightlwings and a rack bar 88 which meshes with a' pinion4 8| rotatable by means of a control lever 82:1 Shifting of the lever spring 58, thus decreasing or, increasing the speed cylinder in which in ,xnounteda servo' piston l 4l. .The arrsngementis such that when the pis.,

ton 4411s moved in.'the-dlrection of the arrow b i in Figure '2,.the .huid 4I is forced through` the pipe 88 intol the' outer end of the cylinder 38 and einst the plston'll so as to move the latter inwardly 'toward the axlsof .rotation and 1 at which the governor will respond for effecting "-its control. `thrust bearing 88 and being slidable through the hub ofthe yoke 88 is a'stem.- 88 equipped at its lowerend with agrooved collar I4. One end of a .lever 88 is received in the collar groove and the Extending. r downwardly from the other end of the lever is arranged to engagesef lectively contact points 88 and 81. The lever 8l itself is connected through a conductor 8l ground.

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The contact point 88 leads through a conductor 69 to one side osmotor reversing mechanism indicated at and the bontact point 81 leads through a) conductor 1| tothe other side of thev s l 3 cumming num to leak out er the chamber im the system piping. For preventing this, the valve is arranged to be closed automatically in rccontinue to operate aty the desired substantially constant speed until some change in the driving conditions causes the load either to increase resulting in a tendency of the engine to Slow down,

or to decrease resulting in a tendency for the en-y gine to increase in speed. -If it be supposedthat the load increases and the engine speed decreases,

the governor y weights v51 will be moved inwardly by pressure exerted by the spring 68, thereby lowering the governor stem 63 and moving the contact lever 85 into engagement with the coni.

tact point S6. The circuit through the-battery l2, the ground, and the conductor 69 to the motor reversing` mechanism 18 will'cause the mo0 tor d2 to run in a direction so as to move the screw 48 in the direction of the arrow a'in Figure 2. This will move the piston 40 also in the direction of the arrow a so as to permit the piston'31 to move outwardly in the cylinder 38 and allow the Vcrcsshead I8 and pinl I9 to move toward a concentric position. The rate of pump dischargewill be .decreased more than. in .proportion to the decrease of the engine speed. When the eccentricity of the crcsshead pin I9 is reducedthe torque reaction on the vengine drive shaft 2 is lessened and the engine speed will increase until the governor responds tomove the contact lever 65 out of engagement with the contact point 88. v As soon as this has happened the motor 42. will cease operating and the crcsshead pin I9 will be sponse to the falling of the pressure fluid level in the chamber 29 or the falling of the unit pressure in the chamber. This may be accomplished by any suitable device such as a float-directly responsive to falling of liquid level, or in the form shown, the valve 14 is carried by a Sylphon bellows actuator 18 which is lled with gas under compression and is adapted to expand and close the valve when the-pressure in thevchamber 29,

falls below a predetermined value. For thev purposes of clear illustration the chamber 29 is shown somewhat removed from the cylinders. However, inpractice it is desirable that the chamber be located as close as possible to the pump cylinder or cylinders. In a multi-cylinder pump a separate pulsation dampening chamber may beprovided foreach cylinder, each chamber being positioned adjacent the discharge valve of the associated cylinder.

In order lto maintain the rotor 9 and parts carried thereby substantially in balance, a very heavy iiuid may be used for transmitting movement from the piston 48 to the piston 31. By referring to Figures 2 and 6, it will be seen that when uid is forced into the cylinder 38, a movement of the crcsshead I8 to the eccentric posi- A. A,end of tlebylinder v3,8 and on the opposite side held in its new position of eccentricity until a further change in the load causes the governor to respond again.

If, however, the load should decrease, there would be a tendency for the engine A to increase its speed. I'he governor would then respond to move the lever 65 Iinto engagement with the ccn- ,tact point 81, completing a circuit through the conductor 1I, and causingthe motor 42 to operate so as to move the screw 46, rod 48a andpiston 48 in the' direction of the arrow b; Fluid forced by the piston Minto the cylinder 38 would movel the piston 31 inwardly so as to increase the ecentricity of the crcsshead pin I9. The. rate of shaft 2 wouldbe increased and the engine A would' slow down.

,Figure 3 shows in'some detail the construction of the pulsation dampening chamber 28. It is ofthe rotor axis. The additional heavy fluid has thefeffect of compensating for the shifting of the crcsshead, thus maintaining the rotor substantially balanced. Mercury, which has all the fluid characteristics. required for transmitting motion from the piston 48 to the piston 31 and which also is very heavy, may beemployed for -this purpose.

Figures 7,' 8, and 9 show a modification in which the shifting of the crcsshead pin for controlling the rate of p umpdischarge is eiected by a ily4 weight carried bythe rotor 9. In this embodiment the engine drive shaft 2y is in direct driving connection with the rotor l9 ,'ournalled as at 11.

The cylinders 8 and associated valve equipment, the pistons 8, and connecting rods 20 and 22 are .of the same construction asin the form shown in Figures 1 and 2. Howevenin' the modic'ation, the connecting rods 2Il and 22--are con- As shown in Figures 8 and 9, a governor fly' weight 8| loaddat 8| with lead, mercury, or other heavy material is mounted to slide in the shown as comprising a thermalLv insulated air tight casing with which the delivery pipes 28 and the pipe 38comxnunicate. An inflation valve 14 at the top o f the chamber is provided for introducing elastic fluid, for example air, under' pressure. A normally open valve 15 provides for co munication between thev interior of the chamber and thevpipe 38 under ordinary conditions. However, if the Avehicle should be coasting down a steep hill, there would be .a tendency for the turbine Dto run ahead of, the pump C which might draw all of the pressure uid out of.I the chamber 28 and permit the air or other expansible crcsshead guide I1. The crcsshead 19 isv provided with rack bars 82 and the weight 8| is provided with rack bars 83,'and sets of gearsv interconnect the rack bars for moving the crosshead 18 oppositely to the governor weight 8| when the latter is shifted, the gears being mounted on the crcsshead guide I1 and a strap`84 carried.

thereby.A The gears of e'ach set include a large .diameter gear 85 meshing with the rack 82, inter` mediate small diameter gears 88- and 81, and a.

to increase the eccentricity of the pin v18 and thereby increase the rate of pump discharge.

Inl order to assure that the engine maybe i lever 93 is operated to move the disc 89 to the position shown in dotted lines in Figure-7 wherein the crosshead pin extension 80 is received and held by the sleeve 90. During normal operation, if the lever 93 be mishandled in a manner tend- -ing to move the disc 89 to its operative dotted" line position, no harm could be done because the rounded end of the crosshead extension 80 would engage the disc and prevent its being moved appreciably.

Figure 10 shows a modified form of governor which may be used in place of the governor 43 shown in Figures 1 and 2 for responding to a sudden wide opening of the throttle valve of the engine A for decreasing the load on the engine and thereby preventing knocking. The modied governor generally designated includes a casing |02 on which is journalled a rotary yoke |03 equipped with a bevel gear |04 meshing with a bevel gear |05 fast with the gear 52 which is driven by the gear I6 on the engine shaft 2. Fly

weights |06 pivoted on the yoke |03 are provided with wings underlying a thrust bearing |01' suspended from which is a stem |08.y A strut |00 is interposed between thrust bearing |0'l and a flexible corrugated disc-like diaphragm H0. At its lower end the stem |08 is equipped with a. grooved collar which receives one end of 'the contact lever 65 whose other end is cooperable with contact points 66 and 6l as in the embodiment shown in Figures l and 2. The top of the governor casing |02 and the diaphragm |||i conjointly denne a chamber through a pipe ||3 to the intake manifold of the engine A, a throttle valve IN being interposed in the manifold.

In operation, with the engine A running at its selected speed and driving through the transmission under normal load conditions, a sudden opening of the throttle valve H4 will result in a lessening of vacuum or stated differently, an increase in pressure in the manifold l and the chamber 2. The diaphragm ||0 normally hel'd slightly elevated by the vacuum in the chamber H2, will then be pressed downwardly by the increased pressure and the resiliency of the diaphragm itself to cause the strut |09 to bear upon the thrust bearing |01 against the lifting urge of the y weights |06, thereby'lowering the stem |09;and causing the lever 65 to engage the contact point fili.v As previously explained, such en-` gagement will close a circuit through the conductor 69 to the reversing mechanism l0 to eiect operation of the motor 42so as to move the screw 46, rod 40B, and piston 40 in the direction of position of the crossheadpin |8.-

H2 connected cylinder, a piston reciprocable in said cylinder,A

a power driven rotor including a central portion formed as a servo cylinder, a pin for operating said piston, means mounting said pin on said rotor for movements selectively to positions concentric with and eccentric to the 4axis of said rotor, a pin-positioning cylinder carried by and being rotatable with said rotor, a pin-positioning piston reciprocable in said pin-positioning cylinder and being connected to said pin, means providing communication between said servo cylinder and said pin-positioning cylinder, a servo piston reciprocable in said servo cylinder, and means for moving said servo piston to apply iiuid pressure upon said pin-positioning piston to move said pin to eccentric position'in opposition to the reactance thrust of the pump piston.

-2. In a variable discharge pump, a stationary cylinder, a piston reciprocable in said cylinder, a power driven rotor, a pin for operating said piston, means mounting the pin on said 'rotor for movements selectively to positions concentric with and eccentric to the 'axis of said rotor, a pinpositioning cylinder carried on said rotor, a pinpositioning piston recprocable in said pin-positioning cylinder on one side of the rotor axis and being connected to said pin for shifting the latter from its concentric position to the other side of the rotor and means for forcing fluid under pressure into saidr pin-positioning piston and thereby shifting said pin to an. eccentric position on said other side of said rotor axis, the weight of iluid so forced into said pin-positioning cylinder tending to counter balance the weight of the pin in its eccentric position.

3. Mechanism as set forth in claim 2 in which the iiuid forced into the pin-positioning cylinder is heavy and comprises mercury.

4. In a variable discharge pump, a stationary cylinder, a piston reciprocable in said cylinder, a power driven rotor, a pin for operating said piston, means mounting the pin on said rotor for movements selectively -to positions concentric with and eccentric to the axis of said rotor, and means for setting the pin in adjusted position on said rotor including a governor weight mounted to move on and relatively to said rotor, a rack on said governor weight, a rack' movable with said pin, and a gear train between said racks for moving thegovernor Weight in one direction away from the rotor axis when the pin is moved in thecpposite direction to an eccentric position.

5. In a variable discharge pump, a ystationary cylinder, a piston reciprocable in said cylinder, a power driven rotor, an operating pin for operating said piston, means mounting the operating pin on said rotor for movements selectively to positions concentric with and eccentric to the axis of said rotor, means for setting the operating pin in adjusted position on said rotor, an exten-a sion on said operating pin, a xed pin having a. stationary mounting and being coaxial with said rotor, a sleeve slidable on said xed pin, and

means for projecting the sleeve from a retracted inoperative position to encompass the operating pin extension and lock the operating Din in its concentric position.

6. Mechanism as set forth in claim 5 in which the sleeve is provided at its end adjacent the operating pin extension with a disc engageable with the operating pin extension for arresting movement of the sleeve toward the operating pin extension when the operating pin is in .eccentric position.

7. In a variable discharge pump, a cylinder and a piston reciprocable therein, a pin connected to said piston, means for electing rota,-

to the other, means mounting the pin to move to positions'eccentric to the axis of rotation, means for moving said pin to a selected position of eccentricity including. a screw, rotatable means having threaded engagement with lsaid screw,-

means mounting said rotatable means for rotation and maintaining said rotatable means againshmovement axially with respect to the screw, electrically driven means for rotating said rotatable means to thereby impart longitudinal movement to the screw, a servomotor operable by Alongitudinal movement of said screw, a fluid pressure operable device for moving said pin to .said eccentric positions,.and conduit means for sitioning uid pressure cylinder and being con-4 nected to said pin :'and means for applying fluid pressure to said pin-positioning fluid pressure piston for shifting said pin to eccentric position.

9. In a variable discharge pump, a stationary cylinder, a piston reciprocable in said cylinder, a

\ power driven rotor, a crosshead guide on said Ation of said cylinder and said pin one relatively conducting fluid under pressure from said servomotor to said fluid pressure operable device.

8. A variable discharge pump comprising a stationary pump cylinder; a pump piston reciprocable in said cylinder; a rotor; a pin for operating said piston; means mounting said pin on said rotor for movements selectively to positions concentric with and eccentric to the rotor axis; a pin-positioning fluid pressure cylinder carried on and rotatablewith said rotor; a pin-positioning to said piston, means pivotally connecting the other end of said connecting rod to said crosshead, and means for shifting said crossheadalong said guide to positions of different eccentricity with respect to said axis of rotation.

10. In a variable discharge pump, a stationary cylinder, a piston reciprocable in said cylinder,

a power driven rotor, a pin for operating said f piston, means mounting said pin on said rotorkfor movements towards and from a position of concentricity with respect to the axis of rotation of said rotor, a. connecting rod operatively connecting said pin to said piston, and meansr for movingsaid pin .to one side of said rotor axis of rotation and for simultaneously applying Weight to a point on said rotor on the opposite side of said rotor axis of rotation.

LYMAN c. BLAIR.`

iiuid pressure piston reclprocable in said pin-po-

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