US2917898A - Differential hydraulic pumps, motors and transmissions - Google Patents

Description

' Dec. 22, 1959 F. BERRY DIFFERENTIAL HYDRAULIC PUMPS, MOTORS AND TRANSMISSIONS Filed Aug. 29, 1957 8 Sheets-Sheet 1 nae-5H1 IN VEN TOR.

FRANK BERRY F. BERRY DIFFERENTIAL HYDRAULIC PUMPS. MOTORS AND TRANSMISSIONS Filed Aug. 29, 1957 8 Sheets-Sheet 2 HEB 3 CASE Ia fix E R w 8 E R P W m INVENTOR.

FRANK BERRY 3:2 HIGH PRESSURE ATTOIWEYS.

W BF/W% Dec. 22, 1959 F. BERRY 2,917,898

DIFFERENTIAL HYDRAULIC PUMPS, MOTORS AND TRANSMISSIONS Filed Aug. 29, 1957 8 Sheets-Sheet s LOW PRESSURE HIGH PRESSURE II IE: 0 CASE Ib LOW PRESSURE w HIGH PRESSURE HE a 5 CASE INVENTOR.

' FRANK BERRY 4 TTOR/VE' Y9.

Dec.'2 2, 1959 F. BERRY 2,917,898

DIFFERENTIAL HYDRAULIC PUMPS, MOTORS AND TRANSMISSIONS Filed Aug. 29, 1957 8 Sheets-Sheet4 co 'Tuo III-150E IN VEN TOR. FRAN K BERRY Dec. 22, 1959 r F. BERRY 2,917,898

DIFFERENTIAL HYDRAULIC PUMPS. MOTORS AND TRANSMISSIONS Filed Aug. 29, 1957 8 Sheets-Sheet 5 L s8 a: 5 s m o 3 E 2 l E 558 m g l I I 1| I i g l -I ll g I\1 E 2 O .88 5 2 n 3 :19; 2;. if 1 IN A or rl d Q N N I NF 2 3 I E m m k E z; 8 g g m u 6 E E u: I 1- "I U--''' I l M C INVENTOR.

FRANK BERRY I B 8 BY k 3; 3 ATTORNEYS 22, 1959 F. BERRY 2,917,898

DIFFERENTIAL HYDRAULIC PUMPS, MOTORS AND TRANSMISSIONS Filed Aug. 29, 1957 8 Sheets-Sheet 6 8 #8 g J a.

5 0.. o T u E o rco co rm g f 3 u v o T 6658 I; t I I g m 2. :f fi .I 0 I: O H 5, 0 2 1- =1 5% I m In C) I O i a 3 l a 2/0) E Q, m 1: Fl 3 9 l 9 i O I O O INVENTOR.

FRANK BERRY ATTORNEYS.

F. BERRY Dec. 22, 1959 DIFFERENTIAL HYDRAULIC PUMPS. MOTORS AND TRANSMISSIONS Filed Aug. 29, 1957 8 Sheets-Sheet '7 12E moz5 ow w H mm cm... L H w. Om NF 5 n a ll Nm QNI' O0 R m 4 N ll E Y 58m: 6x58 W m i I wmnwmwE I2: F wzcamm Jskzwmwhma K 5 $8 mmammwE nj 5% m 5 ME m 3 Y W B mm 8 7 aw Q. 3 I 3 s I A o 3 mm M 8 .8 /I. mm a 4 m .m o ll: w ll lllllllllllilllllllL Q.

ATTORNEYS.

Dec. 22, 1959 F. BERRY 2,917,898

DIFFERENTIAL HYDRAULIC PUMPS, MOTORS AND TRANSMISSIONS Filed Aug. 29, 1957 a Sheets-Sheet 8 IIOO VARIABLE OUTPUT VOLUME- PRESSURE CURVES FOR A CONSTANT spar-:0 PUMP AS in FIG. 3 (I500 REM.)

400 500 600 700 800 I000 DISCHARGE PRESSURE P.S.l.

nus u 11H] IN 'd '9 MO'H INVENTOR.

FRANK BERRY A TTOENEYS.

United States- Patent DIFFERENTIAL HYDRAULIC PUMPS, MOTORS AND TRANSNIISSIONS Frank Berry, Corinth, Miss. Application August 29, 1957, Serial No. 681,060 11 Claims. (Cl.60--53) The invention relates to differential hydraulic pumps,

motors and transmissions.

SUMMARY variable pressure with a variable speed mechanical input drive. a

When operated as a motor:

Case Ib.Constant speed mechanical output drive with variable volume, and pressure hydraulic input.

Case IIb.--Variable speed mechanical output drive with constant volume and variable pressure hydraulic input.

In each instance, the variable characteristicvolume, pressure or speed, as the case may beis infinitely variable over the entire range of operation for which the unit is designed, andoperation of the unit is completely automatic. The purposes to which this infinitely variable unit can be applied are virtually as broad as the field of hydraulic power units itself. For example, suppose that a pump is needed for operation under conditions Where a constant volume discharge is desirable, but that, as a drive for the pump, there islavailable only a source of power which is fluctuating. With the use of my invention this fluctuating power'can be made to produce a constant volume discharge at variable pressure. Or suppose a hydraulic motor is required to operate at constant speed, but the only available hydraulic power source is one which fluctuates widely in volume and pressure. This would be another instance of the application of my invention for the purpose of accommodating available power sources to differing needs. Thus, if your available power source is variable, and you require a constant speed or constant volume output, this is obtainable by the use of my peculiar device. Taking another extreme, if your available power sourceis constant, and you require a variable speed or variable volume output, this too is available in my invention. As applied to a hydraulic transmission, automatic variation of torque ratio is secured, even though you do Without such common expedients as multiple places or variable displacement cylinders, and without the use of valves or shift levers to alter torque ratios according to numerous devices of that nature to be found in the prior art.

As a practical example of one of many present day.

problems not well answered by existing equipment, con sider the air conditioning of automobiles where it is desired to use the drive shaft of the car as the source ofv power for a refrigeration compressor. The trouble with this is that a refrigerating system designed to operate. efficiently at normal highway speeds will not operate efiiciently at idling speeds or when the car must go. slow in congested trafiic. But my invention makes. it feasible ice to convert power taken off the variable speed drive shaft of thecar into a constant volume hydraulic discharge for operating a compressor at a uniform rate. Result: efi'i cient air conditioning whether on a'super-highway or crawling along in trafiic.

In a preferred construction, my invention'maybe sum marized as follows:

Two rotary abutment power units have a common abutment valve shaft. The casing of one of the units is fixed against rotation, that of the other rotatable about the axis of the common abutment valve shaft and arranged for connection to an external power member; Conduits for high and low pressure fluid each communicate with both power units, connecting them in parallel to conduits external of the power unit combination, these being the high pressure discharge and low pressure return lines in the case of a pump, or the-high pressure fluid source and low pressure return line inthe case of amotor; and the two power unitshave different effective volumetric capacities, by virtue of all of which the action of one of the power units so modifies the action of the other that an infinitely variable ratio is obtainable between mechanical input and hydraulic output when 'the combination is used as a pump, and between hydraulic input and mechanical output when used as a motor. When I say infinitely variable, this means variable in infinitely small increments of volume,'pressure or speed (:r.p.m.), asthe case may be, over the range ofoperatiou for which the combination isdesigned. The power units may be of other known types,,'for example, the gear pump type. When ofthe rotary abutment type,;they may include one or more rotary pistons, and may ha ve. two

' or more rotary pistons valving through one or more abut= ment valve recesses. In generahtherefore, we will have (atlea'st) two rotary members which coact in the con version ofmechanical and hydraulic power, one into the other (i.e., either into the other), theseitwo rotary members being mounted for rotation relativeto one an-. other-and both mounted for rotation absolute (i'.e., relative to. the frame or Casing in which they may be mounted), a third rotary member and a member fixed against rotation absolute which third rotary and fixed members coact. in the conversion of mechanical and hyf draulic power, one into the" other, a positive mechanical driving connection between the thirdrotary member'and one of the other two rotary members, as by being-joined, or. geared, together. Conduits for high and low pressure" fluid communicate both with thejfirst two rotary mem' bars, with the third rotary and fixed members andwith put and. output in terms of the operating characteristics 7 desired, including, for example, infinitely,variable-speed at constant volume and infinitely variable volume at constant'speed, both with regardlto operation'of the devicefla's a pump. and as a motor andas a component ofiahydraulic' transmission. I I e DESCRIPTION With reference tothe drawings, 1 shall now describe the best mode contemplatedby me for carrying out my invert-" Fig. 1 is a-.vertical lo ngitudinal sectional view showing; a pump? which is-=capable of discharging fluid at variable volume and pressure when driven at a constant speed (Case Ia).

Fig. 2 is a transverse sectional view taken on line 22, Fig; 1. t i Fig. 3 is a phantom perspective view of the pump of Fig 5.1 and 2. In simplified diagram, it illustrates the main operating elements and hydraulic circuit.

Fig. 4 is a similar view of the same device, illustrating how it can also be used as a motor capable of operation at constant speed when driven from a fluctuating hydraulic source at variable volume and pressure (Case 111).

5 Fig. 5 is a similar view showing application of the invention to a pump capable of discharging fluid at constant Volume when driven at variable speed (Case Ha). The same structure when used as a motor is capable of operation at variable speed when driven from a constant volume source at variable pressure (CaseIIb).

Fig.6 is a vertical longitudinal sectional view showing the application of my invention as a component of an automatic hydraulic transmission in a form similar to Fig. 5 when used as a motor (Case IIb).

Fig. 7 is a phantom perspective view of the transmission of Fig. 6. In simplified diagram, it illustrates the main operating elements and hydraulic circuit under operation in difierential drive.

Fig. 8 is a similar view showing operation in direct drive.

Fig. 9 is a similar view showing operation under the condition described as differential braking.

. Fig. 10 is a graph showing test results on several constant speed, variable volume, pumps constructed in accordance with my invention.

Variable volume pump Here follows a description of an embodiment of my invention according to Case Ia. Refer to Figs. 1, 2, 3 and 10.

First reference is to Fig. 3. This embodiment includes, in its general arrangement, two rotary components which coact in the conversion of mechanical and hydraulic power, one into the other, one of these rotary components being a cylinder casing 11, with related structure, and the othera rotary abutment 12. The cylinder casing 11 is mounted for rotation around the axis of the rotary abutment and the related structure includes a pair of annular cylinders 13, 14 and pistons 15, 16 in the cylinders valving through a recess 17 in the rotary abutment. The two rotary components 11 and 12 are designated as a set of coacting power conversion members A. A third rotary component and a component fixed against rotation coact 1n the conversion of mechanical and hydraulic power, one into the other, this third rotary component in this case being a rotary abutment 18 and the fixed component being a cylinder casing 19, with related structure. This cylinder casing is secured, as at 20, to a frame or housing, and the related structure includes a pair of annular cylinders 21, 22 and pistons 23, 24 in the cylinders valving through a recess 25 in rotary abutment 18. These rotary and fixed components 18 and 19 are designated as a second set of coacting power conversion members B. Thus we have two sets of coactingpower conversion members A and B. The inventive concept can be expressed in its simplest terms by directing attention at this point to the primary members 11, 12 of set A, and 18, 19 of set' B, realizing that the related secondary structure will vary according to the particular type and construction of the power conversion units selected for use in my differential combination. Various types of such power conversion units are, in themselves, well known in the art, as, for example, the several rotary abutment types, the so-called vane type and the ordinary gear pump type. Each of these types includes two primary rotary members one of which rotates relative to the other, as a rotor and cylinder casing. A positive driving connection is madebetween rotary abutments 12 and 18,'as by securing them to a common shaft, as shown. Rotary cylinder casing 11 is arranged for connection to an external power member, as at 26. Conduits 27, 28 for high and low pressure fluid are provided, each conduit communicating with both sets of coacting power conversion members A and B and with external conduits 29, 30; and the respective sets of coacting power conversion members have different effective volumetric capacities. In this case, the difference in efiective volumetric capacities is obtained simply by making cylinders 21, 22 wider than cylinders 13, 14, as clearly shown in Fig. 3. The rotary abutments and the shafts of the pistons are geared together for rotation in one to one ratio at 38, 39, 40 and 50, 51, 52.

In the specific embodiment shown in detail by Figs. 1 and 2, cylinder casing 11 is built up of a, series of flat plates 31, 32 and 33, and end housing members 34, 35 and 36a. Annular cylinders 13, 14 are formed by 31, 32, 34 and the rotors of pistons 15 and 16. Shafts 36 and 37, to. which are keyed the rotors carrying pistons 15, 16, are journalled in bearings in 32 and 34. Parts 32, 33 and 35 together form a gear housing for gear pinions 38, 39 keyed to shafts 36, 37, meshing with a gear 40 keyed to shaft 41 journalled in bearings in 32, 34, 35. Rotary abutment 12 also is keyed to shaft 41. Casing 11 is bodily rotatable about the common axis of shafts 26 and 41. Shaft 41 extends into cylinder casing 19 and rotates in a suitable bearing in the end plate 42 of main housing member 43. Shaft 26 is journalled in a bearing in the other end of housing 43. Thus casing 11 and rotary abutment 12 are rotatable relative to one another and are both rotatable relative to housing 43, and these components 11 and 12 constitute what I now refer to as two rotary members mounted for rotation relative to one another and both mounted for rotation absolute.

Cylinder casing 19 is built up of a series of fiat plates 44, V45, 46 and end plates 42, 47, 53. Annular cylinders 21, 22 are formed by 45, 46, 47 and the rotors of pistons 23, 24. Shafts 48, 49, to which are keyed the rotors carrying pistons 23, 24, are journalled in bearings in 45 and 47. Parts 42, 44 and 45 together form a gear housing for gear pinions 5t), 51 keyed to shafts 43, 49, meshing with a gear 52 keyed to shaft 41 (or, as shown, to a shaft splined to shaft 41 and here regarded as being a part of a single shaft assembly 41). Rotary abutment 18 also is keyed to shaft assembly 41. Casing 19 is fixed as a part of housing 42, 43, end plate 42 of the housingbeing a member common to both the housing 42, 43 and casing 19; and rotary abutment 18 is rotatable relative to this fixed casing. Thus the components 18 and 19 constitute what I now refer to as a third rotary member and a'member fixed against rotation absolute.

Members 36a and 53 contain suitable shaft sealing glands, and each member also. is formed with annular passages communicating with the inlets and outlets, respectively, of the annular cylinders 13, 14, 21 and 22. and communicating. with each other through passages 54. 55 extending through shaft 41 in the manner shown in Fig. 1. Passages 54, 55 form sections of the conduits 27, 28, respectively, these being the conduits I described before as each communicating with both sets of coacting power conversion members A and B and with external conduits 29, 30.

Operation of this unit is as follows, see Figs. 3 and 10:

Suppose first that external high pressure discharge conduit 29 is closed and that cylinder casing 11 is driven by an electric motor at constant speed. Casing 11, rotating relative to rotary abutment 12, pumps oil from A into B, converting mechanical power of rotating input shaft 26 into hydraulic power. This hydraulic power is reconverted to mechanical power in B, rotating shaft 41 and rotary abutment 12 in the direction shown by the arrows, i.e., clockwise. As rotation of casing 11 is counterclockwise, this clockwise rotationof abutment 12 increases the pumping action in A, which in turn increases the speed at which shaft 41 is driven by B. The charactatistics .of the unit are determined by the difference in theefiective volumetric capacities of A and B, B being the larger of the two. Withexternal discharge conduit 29 closed, .we have what is 'known as the shutoff position .of the pump, with no flow and maximum pressure at the shutoff valve. Fig. shows this'pressure for various ratios, of volumetric capacity, expressed as For example, when the volumetric capacity of B is 4.39 times that of A, we see from the curve bearing the notation 4.39 to 1 that when shaft 26 was driven at 1500 .r.p.m., the shutoff head pressure on the unit tested was approximately 600 p.s.i. '(lbs. per sq. in.).

,NOW assume that liquid is drawn ofi at discharge conduit 29 and used to operate an external hydraulic motor whose discharge is returned to low pressure intake conadllit 30. If a constant horsepower, between limits, is maintained on-theexternal hydraulic motor, I have found it possible to drive it at infinitely variable speed and torque, depending upon the load applied to its output shaft. Thus at zero pressure on the 4.39 to 1 curve in :Fig. 10, we find :a maximum flow of about 56 g.p.m., .driving the external motor at maximum speed; and at .400'p.s.-i., allow of about 40,g.p.m.

As the diiference-in the volumetric capacities of A and B becomes less, higher discharge pressures are obtained, approaching an infinitely high shutoff head. See the curve marked 2.84 to 1 volumetric ratio. The volurnetric ratio will be selected in accordance with the particular performance characteristics desired in a given application. For .example,,should a ratio of normal operating pressure to shutoff head of 4:1 be desired, then a ratio of 4.39:1 .as shown won the family-of curves, would be acceptable. The operating pressure of 150 p.s.i. of the unit represented by the 4.39 curve would deliver 52 /2 gallons :per minute, and at the shutoff head of 600 p.s.i., .the delivery becomes 0, thus resulting in an operating range in pressure .of 0 to 600 p.s.i., and a discharge in gallonsperminute of '0 to 56. In case of pressures in the neighborhood of 75 p.s.i. to a shutoff head of 350 p.s.i., then a ratio of 5.94:1 would be desirable. The shutoff head characteristic of my invention eliminates the need for valves. In a circuit where this is desired, the shutoff head is an important factor in the selection of thevolumetric ratio of my differential system. It will be noticed from the family of curves in Fig. 10 that :as :the ratio decreases, the shutoff head p.s.i. increases and the fiow in .g.p.m. approaches a straight line. Were it possible .to construct a unit with 100% efficiency, a :slight differential between the volumetric capacities of sections A and B would result in an almost infinitely high 'shutofi pressure, and the variation in flow would be almost infinitely small throughout the entire operating range of the unit. Constant speed motor Fig. 4 illustrates how the variable volume pump of Figs. 1 to 3 can also be used as a motor capable of operation at constant speed when driven from a fluctuating hydraulic source at variable volume and pressure. This is Case Ib' according to the general outline presented in the summary, infra. As the structure may be identical to that already described, it will suffice to compare briefly the hydraulic circuits and internal shaft rotations of Figs. 3 and 4. What Was the high pressure discharge conduit 29 0f the pump, Fig. 3, becomes the low pressure return conduit 29 of the motor, Fig. 4. What was the low pressure return conduit 30 of the pump becomes the high pressure fluid source for operating the motor. Direction of flow through the system remains the same. High and low pressures within the systems may be easily discerned from the legend in the drawings, high pressure being indicated by the more closely packed molecules. This ispnly .anabstractiondntended to ,be suggcstiveof relative Constant volume pump This is Case Ha of "the Summary outline, and it is illustrated in Fig. 5. The pump structure may be ex- :actly like that described with reference to Figs. 1 to 3, except that in this case the first set of coacting power conversion members, set A, has a larger volumetric capacity than that of the second, set B. In each case the respective sets of coacting power conversion members have different effective volumetric capacities, as

follows: Case Ia, Fig. 3, A 'B. Case IIa, Fig. 5, A B. The relative volumetric relationship of A and B establishes the volume being pumped as a constant since the relative speeds of the two sections will remain constant. The result, in Case Ila, is a constant volume, or rate, of pump discharge with variable pressure and a variable speed of mechanical input drive. The efficiency of this pump is high because all of the torque applied to the pump is used in the pumping operation, the horsepower being substantially constant for all practical purposes.

Variable speed motor This is Case Ilb of my outline. It is to Case I-Ia as Case IE2 is to Case Ia. The structure remains identical :and therefore is illustrated by Fig. 5, except that high pressure becomes low pressure and vice versa. The :load on the output shaft determines "resistance to rotation of thecasing of A. In the caseof a stall position of the output shaft, maximum torque will be maintained, with no rotation. The rotary abutments of A and BC, with their common connecting shaft will rotate in accordance with the volumetric ratio. The result is a variable speed mechanical output drive with constant volume and variable pressure hydraulic input.

Automatic variable torque transmission Figs. 6 to 9, inclusive, show the application of my invention as a component of an automatic hydraulic power transmission. I refer first to Fig. 7. The sets of coacting power conversion members A and B correspond essentially to A and B of the variable speed motor just described as Case IIb. Conduits 29 and 30, as before, are the source of high pressure fluid and the low pressure return line, respectively. However, here the external pump C is incorporated into the system. The shaft 56 of this external pump extends through a bore in the common shaft 57 which connects the rotary abutments of the two sets of coacting power conversion members A and B. In the specific embodiment shown in Fig. 6, shaft 57 is keyed to abutment 12 of set A, .and is an integral part of abutment 18 of set B. Shaft 56 becomes the driven, or output shaft of the complete transmission. The input shaft 58 drives the cylinder casing 59 of pump C. As before, casing 19' :of section B of the variable speed motor A, B, is fixed against rotation at 20, in this case being secured to the transmission housing 60. Casing 11 of motor section A drives shaft 56 through a suitable connection such as a Sprague coupling or other device 61 which will allow driven shaft 56 to overrun casing 11', but which locks casing'll and shaft 56 together whenever the casing tends to rotate faster than the shaft. A braking clutch is provided, this clutch including a .disk member-62 on casing 11' by means of hydraulic plungers 64 sliding in complementary cylinders formed in the casing. Disk 63 is movable into driving engagement with disk 62 when hydraulic fluid is admitted to the cylinders under pressure. When this pressure is released, a biasing spring 65 (Fig. 6) returns disk 63 to the position shown in Figs. 6, 7 and 8, disengaging the clutch.

Passages 66, 67 extending through shaft 57 correspond to passages 54, 55 of Fig. l forming sections of the conduits 27 and 28 described as each communicating with both sets of coacting power conversion members A and B and with external conduits 29, 30. These passages .66 and 67 communicate with annular passages in casing members 68, 69 and 70 in the manner which will be understood from Fig. 6. Casing member 70 is formed with radially extending cylinders for a pair of centrifugal valves 71 and 72, which are in the way of high pressure conduit 29 between pump section C and motor sections A, B, Fig. 7. Valve 71 also communicates with a bypass conduit 74 to the low pressure return conduit 30 of pump section C. These valves are biased toward the axis of rotation of casing 59 as by means of the springs shown in Fig. 6. The outer end of the cylinder of valve 72 communicates via suitable passageways with a governor pressure line 73. Casing member 69 of motor section B is formed with a cylinder for a diiferential pressure actuated valve 75 which is in the way of a by-pass conduit 76 between the high and low pressure conduits Z7 and 28. The two spools of valve 75 have different effective areas, Fig. 6, and are spring biased in one direc tion. The compression of the spring is adjusted so that the valve will open the by-pass to prevent damage to the transmission upon too sudden deceleration under engine braking, i.e., where the engine compression is used as a brake.

' A governor pump 76a driven by shaft 56 discharges hydraulic fluid at governor pressure to governor pressure line 73 via line 77 and valve 78. Valve 78 has multiple spools and is designed so that in one position it will block passage 79, Figs. 7 and 8, and in another position block passages 80 and 81, Fig. 9, in each instance leaving other passages open, including passage 77. This valve is operated by the engine accelerator, and thus occupies the position shown in Figs. 7 and 8 during all driving conditions except that which obtains when the engine is idling, as when standing or when using the engine as a brake. A governor modulating valve 82, operated in accordance with the speed of output shaft 56 by a fly-ball governor 83 driven from the shaft by helical gears 84 is in the way of passage 80. Passages 79 and 81, through accelerator-actuated valve 78 alternately connect the high and low pressure sides of governor pump 76a with the cylinders of hydraulic plungers 64 to operate the braking clutch member 63. A reverse gear of any known construction, e.g., a planetary type, may be provided at 85 for reversing the direction of rotation of output shaft 56 as desired. Governor pump 76a and governor 83 are mounted within a housing 86 fixed to main housing 60.

Centrifugal valve 72 associated with the rotary casing 59 of pump section C is also a differential pressure actuated valve, i.e., the two spools of this valve have different effective areas, Fig. 6, the spool which is farther from the axis of rotation of housing 59 being the larger of the two.

Except in respect of the particulars already described, the details of construction of pump section C, and of motor sections A and B, Fig. 6, are of the same kind as have been set forth at greater length with reference to the pump sections A and B in describing Figs. 1 and 2, q.v. I

Essentially the operation of motor sections A, B of the automatic transmission is the same as that of the variable speed motor described with reference to Fig. 5,

pump C in this case providing the external source of high pressure fluid. However, a further operating variable is introduced by reason of the fact that the abutment rotor of pump section C is keyed directly to the output shaft 56 of the transmission extending as we have seen, through a bore in the common shaft 57 which connects the rotary abutments of the two sets of coacting power conversion members A and B of the motor. Now, since the casing 11 of motor section A drives the output shaft 56 through the coupling 61 whenever its speed exceeds that of the output shaft, this means that the motor also drives the rotary abutment of pump section C under these conditions. When this happens the pumping action of section C is slowed because output shaft 56 is rotating in the same direction as casing 59 of the pump section. Thus the pump section C, acting through hydraulic conduits 29 and 30, activates the interacting motor sections A and B which in turn modify the action of section C. Again the eifect of the modification in the pumping action is felt by the two interacting sections A and B. As we have seen, in the variable speed motor A, B, speed of rotary casing 11 is infinitely variable over its operating range with constant volume and variable pressure hydraulic input. Here we have superimposed a variable volume input because the variation in motor speed is varying the pump speed. Thus in effect we are superimposing, one upon the other, two infinitely variable operations.

I will now describe in more detail the operation of the transmission throughout the differential driving range. Before entering this range, with the motor idling, centrifugal valve 71 of pump section C will be inwardly biased by its spring so as to close conduit 29 between the pump and the motor,.and to open a passage to the bypass conduit 74. Under these conditions the hydraulic fluid flowing from the high pressure side of the pump simply returns to the pump intake and is recirculated without developing any substantial pressure head. Now, as the pump casing 59 is accelerated to enter the driving range, valve 71 moves outwardly under centrifugal force and directs the flow of hydraulic fluid from by-pass conduit 74 to the high pressure line 29 leading to the two motor sections A and B. As the pump housing 59 rotates, the piston rotor shafts S7 and 88 rotate in the same direction about their longitudinal axes and their longitudinal axes have a circular motion about the longitudinal axis of output shaft 56. This motion is in the same direction as input shaft 58. Fluid entering the 'motor section B under pressure causes piston rotor shafts 48 and 49 to rotate in a direction opposite to that of shaft 58. As housing 19' of motor section B is fixed, shaft 57 will rotate in the same direction as shaft 58. High pressure fluid entering the motor section A causes piston rotor shafts 36 and 37 to rotate in the same direction as shaft 53. Housing 11 of this section is free to rotate about shaft 57 and does so with the same direction of rotation as shaft 58. Shaft 57 is rotating in the same direction as 36 and 37 but at a slower rate.

As we have seen, when the speed of housing 11 tends to go above that of shaft 56, the housing is locked in driving relation to the shaft by the Sprague coupling 61 with the result that the driving torque of housing 11' is transmitted to the shaft 56, adding to the torque derived from the pump action of pump section C. As the speed of shaft 56 increases, the volume of fluid accepted by unit A increases and thus leaves a smaller amount for B. This decreases the speed of shaft 57 and further increases the speed of housing 11'.

It should now be observed that the action of valve 72 is responsive to these several forces: (1) centrifugal force, (2) pressure in high pressure line 29 acting on the differential areas of the two spools, (3) biasing force of the spring on the top of the valve, Fig, 6, and (4) pressure in the governor pressure line 73 also acting on the top of the valve. The pressure in line 73 is that created by governor pump 76a as modulated by valve 82 actuated by governor 83 driven from the output shaft. Modulating valve '82 permits excess pressure from pump 76a to bleed back into the low pressure side of the hydraulic circuit of pump 76a irrespective of the operation of governor 83, through compression of spring 89. However, when output shaft 56 reaches a predetermined speed in relation to the setting of governor 83, valve 82 'is withdrawn to the position shown in Fig. 8, releasing pressure on the output side of governor pump 76a suffic'iently to lower the pressure in governor pressure line 73. The proper combination of speeds and pressures will cause'valve 72. to move outwardly and stop all flow from pump section C to motor sections A and B. This places the transmission in direct drive, which is the condition illustrated in Fig. 8. Here the hydraulic lock is secured by operation of valve 72 to close the outlet from pump section C, which prevents piston shafts 87 and 88 from rotating about their longitudinal axes. This in turn prevents rotation of shaft 56 with respect to housing 59 and input shaft 58. Consequently output shaft 56 is driven at the same speed as input shaft 58, with no "flow of hydraulic fluid through the motor.

Fig. 9 illustrates the condition which I describe as dif- *ferential braking. Remembering that valve 78 is connected to the accelerator of the prime mover which is driving input shaft 58, we consider now that the accelerator pedal is released, closing the throttle down to idling speed and permitting valve 78 to move from the position shown in Fig. '8 to that shown in Fig. 9, This closes passages 80 and 81, and opens passage 79. The connection from governor pump line 77 to governor pressure line 73 remains open. Now with full governor pump pressure acting in line 73 and in the now opened passage 79, two effects occur: valve 72 is forced inwardly to allow flow from the motor to the pump and hydraulicplungers 64 are activated to engage the clutch 62, 63. Excess pressure in governor pump discharge line'77 is relieved to the low pressure governor intake by a pressure relief valve 90 in a bypass line 91. Now the load on the output shaft 56 drives the motor A, B as a pump which in turndrives pump section C as a motor to turn the'prime mover against its own compression, the prime mover now acting as a brake. Considering this more in detail, with the clutch engaged, housing 1 1 driven by shaft 56, rotates in the same direction as this shaft; thus piston rotor shafts 36 and 37 rotate about their longitudinal axes in the same direction as shaft 56.

The'resulting action of section A as a pump creates pressure in line 28 which causes piston rotor shafts 48' and 549' tto rotate in the same direction as shaft 56. Shaft E57':th.us rotates in the opposite direction to shaft 56 and .alsoxopposite to that of 36' and 37'. This tends to in- .crease the pumping action of section A. Pressure is also transmitted through conduit 30 to pump section C. This causes piston rotor shafts 87 and -88 to tend to rotate in the same direction as shaft 57. The housing 59 and shaft 58 will rotate in the same direction as shaft :56, .thus driving the prime mover engine and providing the engine braking.

It is possible for shafts 87 and 88 to rotate in the oppo site direction'from that of shaft 56 but the tendency to rotateiin the same direction as this shaft will drive the prime mover in the desired .direction which is that of the shaft.

Engine braking will continue until the accelerator is again depressed, shifting valve 78 back to the position shown in Figs. 7 and 8. Operation will then be either differential drive, Fig. 7,'or direct drive, Fig. 8, depending on the speedand'torque conditio'ns obtaining.

' In describing the operation of the several embodiments of. my invention, 'I have attempted in some degree to explain; the interaction of the several components each ,upon the others, and to suggest a. theoreticalbasis for the results obtained. ,It is difficult to know whether my analysis is correct in all particulars, because there are so many variables to be carried in the mind. The problem arises partly because of the need to consider rotations of many parts both in the absolute and relative senses, and in part becauseof considerations encountered where a unit B modifies the action of a unit A which, in turn, again modifies the action of unit B. And in the embodiment of Figs. 6-9, we have a further variable introduced by the consideration that unit C activates the interacting units A and B which in turn modify the action of unit C. I emphasize this point here, for I wish to make it very clear that I am not resting my case on any particular theory as to why the invention works the way it does. 'I simply know that when the several components embody the main features and relationships I have described and claimed, the advantages of my invention are available, and, since the operation is in any event fully automatic, it is not essential that the why of its operation be fully comprehended.

The terms and expressions which I have employed are used in a descriptive and not a limiting sense, and I have no intention of excluding such equivalents of the invention described, or of portions thereof, as fall within the scope of the claims.

h 11 claim:

1. In a rotary hydraulic power device, two rotary membersconstituting a first set of members which coact in the conversion of mechanical and hydraulic power, one into the other, said two rotary members mounted for rotation relative to one another and both mounted for rotation absolute, a third rotary member and a member fixed against rotation absolute, said third rotary and fixed members constituting a second set of members which coact in the conversion of mechanical and hydraulic power, one into the other, a positive mechanical driving connection between said third rotary member and .one of said two rotary members, the other of said two rotary members having means for connecting it to an external power member, and conduits for high and low pressure fluid, .each of said conduits communicating both with said two rotary-members, with said third rotary and fixed members and with external conduits so that the two sets of members which coact in the conversion of mechanical and hydraulic power are connected in parallel 'to said external conduits, and the respective sets of coacting power conversion members having different volumetric capacities per revolution of said third rotary member, by virtue ofall of which the action of one of said sets .o'f coacting power conversion members so modifies the action vof the .other of said sets that an infinitely variable ratio is obtainable between input and output in terms of the operaing characterisics desired, including, for example, infinitely variable speed at constant volume .andinfinitely variable volume at constant speed, both with regard to operation of the device as a pump and as amotor and as a component of a hydraulic transmission.

.2. .In a rotary hydraulic pump, two rotary members constituting a-first set of members which coact in'the conversion of mechanical power to hydraulic power, said two rotary members mounted for rotation relative to one another and bothmounted for rotation absolute, a third .rotarymemberand amember fixed against rotation ab- ,solute,.said third rotary and fixed members constituting asecond set of members which coact in'the conversion of hydraulicpower to mechanical power, a positive mechanical driving connection between said third rotary member-andone of said two rotary members, and the o'ther oft said two rotary members having means for connectingitto, anexternal source of mechanical power, co'nduitsfor high and low pressure fluid, each of saidtconduits communicating both with the first two rotary memers, with ,said third rotary and fixed members and with external conduits so that the two v sesof memberswhich coact .in .the conversion of mechanical and hydraulic power are connected in parallel to said external conduits, and the respective sets of coacting power conversion members having different volumetric capacities per revolution of said third rotary member, by virtue of all of which the action of one of said sets of coacting power conversion members so modifies the action of the other of said sets that an infinitely variable ratio is obtained between mechanical input speed and rate of discharge of the pump, with constant input speed and variable discharge, and with variable input speed and constant discharge, according to the operating characteristics desired as determined by selection of the ratio between said different volumetric capacities.

3. In a rotary hydraulic motor, two rotary members constituting a first set of members which coact in the conversion of hydraulic power to mechanical power, said two rotary members mounted for rotation' relative to one another and both mounted for rotation absolute, a third rotary member and a member fixed against rotation absolute, said third rotary and fixed members constituting a second set of members which co'act in the conversion of hydraulic power to mechanical power, a positive mechanical driving connection between said third rotary member and one of said two rotary members, and the other of said two rotary members having means for connecting it to an external mechanical load, conduits for high and low pressure fluid, each of said conduits communicating both with the first two rotary members, with said third rotary and fixed members and with external conduits so that the two sets of members which coact in the conversion of mechanical and hydraulic power are connected in parallel to said external conduits, and the respective sets of coacting power conversion members having different volumetric capacities.

4. A rotary hydraulic power device according to claim 1, in which the first set of coacting power conversion members has a smaller volumetric capacity than that of the second set.

5. A rotary hydraulic power device according to claim 1,, in which the first set of coacting power conversion members has a larger volumetric capacity than that of the second set.

6. In a rotary hydraulic power device, two rotary members constituting a first set of members which coact in the conversion of mechanical and hydraulic power, one into the other, one of said rotary members being a cylinder casing and the other a rotary abutment, the cylinder casing mounted for rotation around the axis of the rotary abutment, the cylinder casing having a pair of annular cylinders and pistons in the cylinders valving through a recess in the rotary abutment, a third rotary member and a member fixed against rotation, said third rotary and fixed members constituting a second set of members which coact in the conversion of mechanical and hydraulic power, one into the other, said third rotary member comprising a rotary abutment and the fixed member being a cylinder casing, this fixed cylinder casing having a pair of annular cylinders and pistons in the cylinders valving through a recess in the last named rotary abutment, a positive driving connection between the two rotary abutments, the rotary cylinder casing having means for connecting it to an external power mem her, and conduits for high and low pressure fiuid, each of said conduits communicating with both sets of coacting power conversion members and with external conduits so that both sets of coacting power conversion members are connected in parallel to said external conduits, and the respective sets of coacting power conversion members having diiferent effective volumetric capacities.

7. A rotary hydraulic power device according to claim 6, which includes means for holding the first set of coacting power conversion members against relative rotation when the output shaft becomes an input shaft under overrunning conditions.

8. In combination, two rotary abutment power units having a common abutment valve shaft and each having a casing, the casing of one of said units being fixed against rotation and the casing of the other of said units being mounted for rotation about the axis of said common abutment valve shaft and having means for connecting it to an external power member, and conduits for high and low pressure fluid, each of said conduits communicating with both of said rotary abutment power units and with external conduits so that both of said rotary abutment power units are connected in parallel to said external conduits, and the two rotary abutment power units having different effective volumetric capacities, by virtue of all of which the action of one of said units so modifies the action of the other that an infinitely variable ratio is obtainable between mechanical input and hydraulic output when the combination is used as a pump and between hydraulic input and mechanical output when used as a motor.

9. In combination, two rotary abutment power units each having an abutment valve shaft and a casing, a positive driving connection between the abutment valve shafts of the two units, the casing of one of said units being fixed against rotation and the casing of the other being mounted for rotation about the axis of its abutment valve shaft and having means for connecting it to -an external power member, and conduits for high and low pressure fluid, each of said conduits communicating with both of said rotary abutment power units and with external conduits so that both of said rotary abutment power units are connected in parallel to said external conduits, and the two rotary abutment power units having difierent effective volumetric capacities, by virtue of all of which the action of one of said units so modifies the action of the other that an infinitely variable ratio is obtainable between mechanical input and hydraulic output when the combination is used as a pump and between hydraulic input and mechanical output when used as a motor.

10. In combination, two rotary abutment power units having a common abutment valve shaft and each having a casing, the casing of one of said units being fixed against rotation and the casing of the other of said units being mounted for rotation about the axis of said common abutment valve shaft and having means for connecting it to an external power member, and conduits for high and low pressure fluid, each of said conduits communicating with both of said rotary abutment power units and with external conduits so that both of said rotary abutment power units are connected in parallel to said external conduits, and the two rotary abutment power units having different effective volumetric capacities, a third rotary abutment power unit connected to said external conduits, said third unit including a rotatable casing and an abutment valve with a positive mechanical driving connection to said external power member, and said connection of the rotatable casing of said other of said two first-named rotary abutment power units providing a positive driving connection to said external power member at least under conditions where said last-named rotatable casing tends to rotate faster than said external power member.

11. The combination according to claim 10 in which said external power member is a shaft extending through said common abutment shaft.

References Cited in the file of this patent UNITED STATES PATENTS 1,954,793 Averin Apr. 17, 1934 2,645,903 Elkins July 21, 1953 2,737,020 Berry Mar. 6, 1956 2,750,891 Berry June 19, 1956 2,770,099 Badalini Nov. 13, 1956 2,838,031 Osborn June 10, 1958 2,871,831 Patin Feb. 3, 1959

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