MXPA96002891A - Relationship controller for a transmissionhidrostat - Google Patents

Abstract

The present invention relates to a continuously variable hydrostatic transmission, which comprises, in combination: a housing, an input shaft supported in the housing for receiving a torque from a primary motor, a pump unit including a first carrier driven by the inlet arrow, and which mounts an annular array of pistons of the pump, and a first cylinder block that provides an annular arrangement of the pump cylinders to respectively receive the pistons of the pump, an engine unit that includes a second carrier fixed to the housing, and mounts an annular array of engine pistons, and a second cylinder block that provides an annular array of engine cylinders to respectively receive the engine pistons; an output shaft supported on the housing and adapted for a pulse connection with a load, an annular drive plate that surrounds the output shaft, and which has an input face and An output face configured in an acute angle, one in relation to the other, confronting the entrance face to the first cylinder block, and confronting the exit face to the second cylinder block, also including the motor plate slots that accommodate the flow of fluid pumped between the cylinders of the pump and the cylinders of the engine through openings in the first and second cylinder blocks, a connector that pivotably couples the drive plate to the output shaft in a coupled torque relationship; ratio controller that selectively exerts coordinate axial forces on the first and second cylinder blocks, to adjustably set an angle of the drive plate relative to an output shaft arrow in accordance with a desired speed ratio between the input arrows and of sali

Description

RELATION CONTROLLER FOR A HYDROSTATIC TRANSMISSION This application refers to my International Patent Application Number PCT / U.S. 92/00257, filed on January 14, 1992, entitled "Hydraulic Machine", and to my request entitled "Continuously Variable Hydrostatic Transmission", with Serial number (35-OR-949), filed on. Descriptions of these pending pending requests are incorporated herein by reference.

SUMMARY OF THE INVENTION The present invention relates to hydraulic machines, and more particularly to hydrostatic transmissions capable of transmitting energy from a primary motor to a load at continuously (infinitely) variable transmission ratios.

BACKGROUND OF THE INVENTION In my application of the aforementioned TCP, a hydraulic machine is described which includes a hydraulic pump unit and a hydraulic motor unit placed in an opposite relationship, axially aligned, with a drive plate in the form of an intermediate wedge. The pump unit is connected with a driven input shaft with a primary motor, while the motor unit is grounded in the stationary machine housing. An output arrow, coaxial with the input shaft, and coupled with a load, is connected to the drive plate. When the pump unit is driven by the primary motor, hydraulic fluid is pumped back and forth between the pump and motor units, through gates specially configured on the drive plate. As a result, three torque components are exerted, all acting in the same direction, on the drive plate, to produce an output torque on the output shaft to drive the load. Two of these torque components are a mechanical component exerted on the drive plate by the rotary pump unit, and a hydromechanical component exerted on the drive plate by the motor unit. The third component is a pure hydrostatic component resulting from the differential forces created by the fluid pressures acting on the circumferentially opposite end surfaces of the drive plate gates, which are of different surface areas, due to the wedge shape of the drive plate. To change the transmission ratio, the angular orientation of the drive plate is varied in relation to the axis of the output shaft. Since the ratio of the transmission, that is, the speed ratio, is continuously variable between 1: 0 and 1: 1, the primary motor can work at a constant speed established essentially at its most efficient operating point. The availability of a setting of the transmission ratio of 1: 0 (neutral) eliminates the need for a clutch. Unlike conventional, continuously variable hydrostatic transmissions, where the hydraulic fluid flow rate increases proportionally with the increase in the transmission ratio, such that the maximum flow velocity occurs at the highest setting of transmission, the flow rate in the hydraulic machine described in my application of the cited TCP reaches a maximum at a midpoint in the ratio scale, and then progressively decreases to essentially zero in the highest set of transmission ratio. Accordingly, the losses due to the flow of the hydraulic fluid are reduced, and the annoying moan of conventional hydrostatic transmissions in high proportions is eliminated. By virtue of the multiple torque components exerted on the drive plate, the hydraulic fluid flow decreasing in the upper half of the output speed scale, and the ability to accommodate an input of the primary motor for optimum operation, the machine Hydraulics of my TCP application has a particularly convenient application as a continuously variable, silent and highly efficient hydrostatic transmission in vehicular transmission trains.

SUMMARY OF THE INVENTION An object of the present invention is to provide improvements in the hydraulic machine of my TCP Application PCT / U.S Number. 92/00257, to achieve savings in size, in the parts account and in the manufacturing cost. A further object of the present invention is to provide improvements in the provisions for accommodating high and low pressure hydraulic fluid flows within the machine, and the manner in which the transmission ratio is changed, i.e. the adjustment of the angle of the driving plate. To achieve these objectives, the hydraulic machine of the present invention, in its application as a continuously variable hydrostatic transmission, comprises a housing; an input arrow supported in the housing to receive the input torque from a primary motor; an output arrow resting on the housing for imparting the impulse torque to a load; a hydraulic pump unit including a first carrier driven by the inlet arrow and mounting an annular array of pump pistons, a first cylinder block that provides an annular array of cylinders of the pump to respectively receive the pistons of the pump , and a first spherical bearing that mounts the first cylinder block in relation to the first carrier; a hydraulic motor unit including a second carrier fixed to the housing, and mounting an annular piston arrangement of the engine, a second cylinder block providing an annular array of engine cylinders to receive - respectively the pistons of the engine, and a second spherical bearing that mounts the second cylinder block in relation to the second carrier; a wedge-shaped drive plate including gates extending between an entrance face facing the pump unit, and an exit face facing the engine unit; a connector that pivotally couples the drive plate with the output shaft in a torque-coupled relationship; and a ratio controller that selectively exerts coordinate axial forces on the first and second cylinder blocks, to adjustably establish an angle of the drive plate relative to an output shaft arrow in accordance with a desired transmission ratio. The additional features, advantages and objects of the invention will be stipulated in the following description, and in part will be apparent from the description, or can be learned by practicing the invention. The objects and advantages of the present invention will be realized and will be obtained by the apparatus particularly indicated in the following written description and in the appended claims, as well as in the accompanying drawings. It will be understood that both the foregoing general description and the following detailed description are exemplary and explanatory, and are intended to provide a further explanation of the invention as claimed. The accompanying drawings are intended to provide a further understanding of the invention, and incorporated into, and constitute a part of, the specification, illustrate a preferred embodiment of the invention, and together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a longitudinal sectional view of a continuously variable hydrostatic transmission, in accordance with the present invention, illustrated in a transmission ratio establishment. Figure 2 is a longitudinal sectional view corresponding to Figure 1, illustrating transmission in a different relationship establishment. Figure 3 is a side elevation view of a drive plate used in the transmission of Figure 1. Figure 4 is a side elevation view of an input gate plate used in the transmission of Figure 1. Figure 5 is a fragmentary sectional view taken along line 5-5 of Figure 2. Figures 6 and 7 are opposite side elevational views of a manifold block used in the transmission of Figure 1. Figure 8 is a fragmentary sectional view illustrating the fluid connection between a low pressure cavity in the manifold block of Figures 6 and 7, and a gate of the low pressure housing in the transmission of Figure 1. Figure 9 is a side elevational view of an outlet gate plate used in the transmission of Figure 1. Figure 10 is a schematic diagram of a hydraulic circuit incorporating the transmission of Figure 0 1. The corresponding reference numerals refer to similar parts through the different views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY The continuously variable hydrostatic transmission according to the preferred embodiment of the present invention, generally indicated at 10 in Figure 1, comprises, as basic components, a housing 12 on which an input shaft 14 is supported. and an output arrow 16 in a coaxial relationship, generally end to end. The end of the input shaft 14 external to the housing is toothed, as indicated at 14a, to facilitate the pulse connection with a primary motor (not shown), while the outer end of the output shaft 16 is equipped with a coupling 17 for facilitating the impulse connection with a load (not shown). The input shaft 14 drives a hydraulic pump unit, generally indicated at 18. A hydraulic motor unit, generally indicated at 20, is grounded with the housing 12 in an axially opposite relationship with the pump unit 18. A plate wedge-shaped drive, generally indicated at 22, is impulsively connected with the output shaft 16, at a position between the pump and motor units, and has gate to provide the exchange of hydraulic fluid between the pump and the pump units. motor. A controller, comprised of the elements schematically illustrated in the hydraulic circuit of Figure 10, acts to pivotally adjust the angle of orientation of the drive plate relative to the axis of the output arrow 25, thus establishing the ratio of transmission of the speed of the entrance arrow with the speed of the exit arrow. Referring now to Figure 1 in greater detail, the cylindrical housing 12 includes a cover 30 secured in place by an annular array of screws, one at 31, to close the open inlet end of the housing. The input shaft 14 extends to the housing 12 through a central opening 32 in the cover. The bearings 35, adapted in the opening of the cover 32, support the input shaft 14 for its rotation. Seals (not shown) are included in the opening of the cover 32, in a sealing relationship with the peripheral surface of the entry shaft, to prevent leakage of the hydraulic fluid. The inlet arrow 14 is radially turned to provide an internal bell-shaped termination 36 just inside the cover 30. The peripheral surface of this inlet arrow termination is machined with teeth to provide cylindrical engagement 38 engaged with a cylindrical gear 40, in turn connected to drive a sweep pump 42 positioned in a sump 44 provided with a lower tray 46 secured to the housing 12. The inner end of the inlet shaft 14 has a counter hole to provide a recess cylindrical 47 for receiving an inner terminal portion of reduced diameter of the output shaft 16. The bearings 48, fitted on the recess 47, provide a support support for the inner end for the output shaft. Assembled on the output shaft 16, there is an annular inner end piece 50, an annular pump piston carrier 52, a drive plate coupling 54, an annular motor piston carrier 56, and an annular manifold block 58. The motor piston carrier and the manifold block are grounded in the housing 12 by screws, one being seen at 59. The output shaft is terminated by an integral end piece 60, to which the coupling 17 is fixed by screws, one in 61 being seen. A ring bearing 62, adapted in an outlet opening of the housing 12, provides the bearing support of the output end for the output shaft. The bearings 64 positioned between the output shaft 16 and the pump piston holder 52, and between the output shaft and the motor piston holder 56, provide a support support for these carriers when the output shaft rotates in relation with them. Coupling 54 of the drive plate is coupled with the output arrow, as indicated at 65, and includes a radially extending arm 66 having a hole in which a bolt 67 is received to pivotally and impulsively connect the motor plate 22 to the output shaft 16. A nut 68 on an axial threaded section 69 of the output shaft to hold the end piece 50 and the coupling of the drive plate 54 against a shoulder 70 machined in the output shaft, such that the end piece 50 rotates unison with the exit arrow and the coupling of the drive plate. Still referring to Figure 1, a peripheral surface of the pump piston holder 52 is machined with gear teeth 72 which engage an annular gear 74, as do the gear teeth 38 on the termination of the input shaft. 36, and accordingly, the pump piston holder 52 is urgeably coupled with the inlet shaft 14. The pump piston holder supports a plurality of pistons included in the hydraulic pump unit 18. These pistons, for example, in a number of ten, generally indicating two in 76, are uniformly distributed in a concentric circular array with the axis of the output arrow 25 in the manner described in my TCP request. As illustrated in Figure 1 hereof, each pump piston 76 includes a piston head 78 mounted on the piston holder 52 by an axially extending post 79 threaded into a thinned orifice 80 in the piston holder. In the piston head 78 is machined to provide a spherical inner surface that conforms to a spherical outer surface of an external annular bearing 82 coupled on an inner bushing 83 carried on the free end with shoulder of post 79. As a result, each head piston 78 is mounted for a limited radial and oscillatory movement, as in the case of the hydraulic machine described in my cited TCP application. The cylindrical portion of the right end of the piston carrier 52 of the pump carries an annular spherical bearing 86 which is formed with a spherical surface 87 machined in the central opening of an annular pump cylinder block 88. The cylinder block 88 includes a annular arrangement of cylinders 90 of the pump, to receive respectively the pistons 76 of the pump. By virtue of the spherical bearing assemblies of the piston heads 78 of the pump and of the cylinder block 88 of the pump, the precession movement of the rotary shaft of the cylinder block of the pump is accommodated. Still referring to Figure 1, the hydraulic motor unit 20 is constructed in essentially the same manner as the hydraulic pump unit 18. However, as noted above, the annular motor piston carrier 56, which corresponds to the carrier pump piston 52, is grounded in housing 12 by screws 59. Each of a plurality of motor pistons, generally indicated at 92, and a number corresponding to the pistons of pump 76, includes a piston head 94 oscillatingly mounted on a spherical bearing 96 and a bushing 97 carried on the free end with shoulder of a post 98 threaded towards a thinned hole 99 in the piston carrier 56 of the engine, in the same manner as the pistons of the piston bomb. A cylinder block 100 of the motor is then oscillatoryly mounted on the motor piston carrier by means of an annular spherical bearing 102. Again, as in the case of the cylinder block 88 of the pump, a circular array of cylinders of the motor is formed. motor 104 in the cylinder block 100 of the engine, to receive respectively the pistons 92 of the engine. Since the motor unit 20 is grounded in the housing 12, the pistons 92 of the motor and the cylinder block 100 do not rotate; however, the spherical bearing assemblies of the piston heads 94 of the motor in the poles 98, and of the cylinder block 100 of the motor in the carrier 56, accommodate the inclined (precessing) movement of the shaft of the cylinder block of the motor. . The drive plate 22 is urgently connected to the output shaft 16 by the coupling 54 in an operative position between the pump unit 18 and the motor unit 20, with an input face 110 in an intimate sliding contact with the face 111 of the cylinder block 88 of the pump, and an outlet face 112 in an intimate sliding contact with the face 113 of the cylinder block 100 of the engine. The inlet and outlet faces of the drive plate 22 are relatively oriented at an acute angle to provide the wedge shape of the drive plate. The gates 114, as seen in Figure 3, extend between the entry and exit faces of the drive plate, and communicate with the respective openings 115 towards the cylinders 90 of the cylinder block 88 of the pump, and the openings respective 116 to the cylinders 104 of the cylinder block 100 of the engine, all as described and illustrated more fully in my application of the cited TCP. Figure 3 also illustrates the pivotal momentum connection of the driver plate 22 with the output shaft 16 provided by the coupling 54 mentioned above with respect to Figure 1. Transverse holes 120, transversely aligned, are drilled through an axially flange. thickened from the drive plate 22 and coated with the bushings 121. Then the pivot pin 67 is inserted through the bushings 121 and the hole 122 in the arm 66 to the position shown in Figure 3, a position fixed by a screw No. 123. In accordance with a feature of the present invention, the radial length of the arm 66 is such that the radial offset of the transverse axis of the pivot pin 67 is substantially equal to the spokes (in relation to the axis of the arrow of outlet 25) of the circular arrangements of the pump pistons 76 and the motor pistons 92. This feature allows to make reductions in the overall length of the transmission 10, and at the axial forces required to change the angle of the drive plate relative to the axis of the output shaft 25, that is, the transmission ratio, as described below. Although not shown, the material of the annular end pieces 50 and 60 is selectively removed to balance the eccentric masses of the precession drive plate 22, the cylinder block 88 of the pump, and the cylinder block 100 of the motor, to serve the purpose of separating the balance ring described in detail in my application for the cited TCP. As also described in my application of the aforementioned TCP, the transmission ratio (the speed of the input arrow against the speed of the output arrow) is changed by adjusting the angular orientation of the drive plate 22 in relation to the axis of the output arrow 25. When the input face 110 of the drive plate is perpendicular to the axis of the output shaft, the axis of the cylinder block 88 of the pump is coincident with the axis of the output shaft. Accordingly, the driven rotation of the cylinder block of the pump about its axis is without an axial component of movement and, consequently, no pumping action of the hydraulic fluid is presented by the pump unit 18. This is the position Transmission Neutral 10. In s the angle of the drive plate illustrated in Figure 1, the entrance face 110 of the drive plate is at a slight angle in the counterclockwise direction from the perpendicular to the shaft of the output shaft, and consequently, the axis of the cylinder block 88 of the pump is precessed to a slight corresponding angle relative to the axis of the output shaft. Now, the rotation of the cylinder block 88 of the pump includes an axial component - of movement, and consequently, hydraulic fluid is pumped by the pump unit 18. The angle of the drive plate illustrated in Figure 1 is a reverse set-up, in which the exit arrow 16 rotates at a slow speed in one direction. opposite direction (in reverse) to that of the input arrow. When the drive plate is pivoted on the pin 67 clockwise from the neutral position to the position of the angle of the drive plate seen in Figure 2, the axis of the cylinder block 88 of the rotary pump it precesses through increasing angles in relation to the axis of the output shaft, and also increases the hydraulic pumping action of the pump unit 18. Therefore, the transmission ratio is increased, and the output shaft is driven at increasing forward speeds, and the same direction as the input arrow. When the output face 112 of the drive plate 22 is perpendicular to the axis of the output shaft 25, the axis of the cylinder block 100 of the motor is in coincidence with the axis of the output shaft. Accordingly, there is no pumping action of hydraulic fluid from the motor unit 20. The pump unit 18 and the drive plate 22 are then essentially hydraulically secured without a relative movement between the cylinder block 88 of the pump and the plate motor 22. This is the position of the 1: 1 ratio of the transmission 10. Figure 2 illustrates the output face 112 of the drive plate at a slight angle in the clockwise direction beyond the perpendicular to the output arrow 25. At this angle of the drive plate, an overshoot transmission position is reached, wherein the output shaft 16 is driven at a forward speed in excess of the speed of the input shaft, i.e. , an overshoot position. According to a characteristic of the present invention, the change of ratio of the angle of the drive plate is achieved by exerting coordinated forces on the cylinder block 88 of the pump and the block of cylinders 100 of the motor, induced by the change of the axial positions of the spherical bearings 86 and 102, which assemble the cylinder block of the pump and the cylinder block of the motor, respectively. For this purpose, and as seen in Figures 1 and 2, the spherical bearings 86 and 102 are mounted by their respective pump piston carrier 52 and their respective motor piston carrier 56 for sliding axial movement. As best seen in Figure 2, the pump piston carrier 52 and the spherical bearing 86 are provided with axially opposed shoulders which, in conjunction with the radially opposed skirt portions of the pump piston holder and the spherical bearing, define an annular chamber 130. Similarly, and as best seen in Figure 1, axially opposite shoulders and radially opposed skirts formed in the piston carrier 56 of the engine and in the spherical bearing 102, define an annular chamber 132. In the Figure 1, it is seen that the volume of the chamber 132 is in the state of maximum axial expansion, while the volume of the chamber 130 is in the state of maximum axial contraction. Accordingly, the spherical bearings 86 and 102 have been moved together to the extreme axial positions to the left, as well as the cylinder blocks of the pump 88 and the motor 100, carried by these spherical bearings. When the cylinder blocks of the pump and motor are moved axially to the left, the drive plate 22 is forcibly pivoted in the counterclockwise direction, around the pivot pin 67, to the angle that is seen in Figure 1. To forcefully pivot the drive plate 22 clockwise to the angle of the drive plate seen in Figure 2, the volume of the chamber 130 is axially expanded as it contracts. axially the volume of the chamber 132, to axially move the ball bearings 86, 102 and the cylinder blocks 88, 100, to the right. Referring to Figure 2, to establish a fluid pressure in the chamber 130, an annular inlet gate plate 134 is fixed against the radial face 135 of the annular end piece 50 on the output shaft 16. Accordingly , the output arrow and the input gate plate 134 rotate in unison. A radial flange portion Jj 136 of the pump piston carrier 52 abuts against the right radial face of the gate plate 134, as the piston carrier of the pump, driven by the input shaft 14, rotates in relation to the plate input gate linked to the exit arrow 16. As seen in the Figure 4, the entry gate plate 134 is provided with a pair of circumferentially elongated kidney gates 138 and 140, in a diametrically opposite relationship. The mounting post 79 of the pump piston is axially drilled to form through holes 142, to provide a fluid flow communication between the cylinders of the pump 90 and the gates 138 and 140 of the inlet gate plate 134. Accordingly, the hydraulic fluid of the pump cylinders flows through the holes 142 in the mounting posts of the pump piston to fill the gates 138 and 140 in the inlet gate plate 134. The hydraulic fluid in these gates 138 and 140, therefore, are pressurized according to the fluid pressures in the cylinders 90 of the pump, as the pump unit 18 5 is driven by the input shaft 14. When the pistons 76 of the pump and the cylinder 90 of the pump rotate from the thinnest point of the wedge-shaped drive plate 22 around its diametrically opposite thickest point, the The volumes of the associated pump cylinders decrease progressively, and the hydraulic fluid in these cylinders of the pump is consequently pressurized. This is considered as the high pressure or pumping side of the hydraulic pump unit 18. When the pistons of the pump and the cylinders of As the pump rotates from the thickest point around to the thinnest point of the drive plate 22, the volumes of the associated pump cylinders 90 expand progressively. This is considered as the low pressure or suction side of the hydraulic pump unit 18. Since the gates 13R and 140 are in fluid communication with the hydraulic fluid of the cylinders 90 of the pump through the holes 142 in the piston mounting posts 79, the hydraulic fluid of one of these gates is pressurized to a high pressure corresponding essentially to the average fluid pressures of the hydraulic fluid in the cylinders of the pump involved in the pumping side, and the hydraulic fluid in the other of these gates assumes the average fluid pressure of the hydraulic fluid in the cylinders of the pump involved in the suction or low pressure side of the hydraulic pump unit 18. Turning to FIG. 5, a pair of opposite pierced holes 146 are drilled in the annular end part 50 of the output shaft 16 from the opposite directions. A smaller diameter hole 147 is drilled through the annular end piece 50 between the internal terminations of the holes 146. A longitudinal hole 148 is drilled through the end piece 50 at a radial location, to provide a communication of fluid between the gate 138 of the gate plate 134 and one of the holes 146, wherein a longitudinal hole 149 is pierced through the end piece at a radial location, to provide fluid communication between the gate 140 and the another hole 146. It will be appreciated that the outer ends of the holes 146 are sealed by plugs (not shown). A third longitudinal hole 150 is drilled in the end piece of the outlet arrow 50 at a location intersecting the hole 147 interconnecting the holes 146. As also seen in Figures 2 and 4, the hole 150 is in longitudinal register with an axial hole 152 through the gate plate 134, whose right end opens towards an annular cavity 153 machined in the bearing face 154 of the gate plate. This annular cavity 153 is closed by the radial face of the pump cylinder holder 52 in a sliding coupling with the bearing face 154 of the gate plate 134. Then a longitudinal hole 156 is punched through the pump piston holder 52., to provide fluid communication between the annular cavity 153 and the annular chamber 130, as seen in Figures 1 and 2. Still referring to Figure 5, a double-acting valve 160, operatively placed in the holes of the piece at end 146, includes a pair of valve plates 162 interconnected in an appropriately spaced apart relationship by a shoulder bolt 164 extending through hole 147. Shoulders created at orifice joints 147 with holes 146 provide valve seats 165 for the valve plates 162. In operation, the double-acting valve 160 ensures that only the low-pressure side of the hydraulic pump unit is in continuous flow communication with the chamber 130. Therefore, as illustrated in FIG. Figure 5, gate 138 of gate plate 134 is on the high pressure side, and consequently, double-acting valve 160 assumes the position shown in FIG. sealing the chamber 130 of the high pressure fluid of the gate 138. The chamber 130, therefore, is in flow communication with the low pressure fluid gate 140 via the orifice 149, the orifice 146, the orifices 147. and 150, the annular cavity 153, and the orifice 156. It will be noted that the annular cavity 153 ensures a continuous flow communication between the orifice of the gate plate 152 and the orifice of the piston carrier 156, independently of its angular locations. relative. It will be appreciated that, due to the investments in torque during the acceleration ít) and the deceleration, sometimes the gate 138 may be on the low pressure side, and the gate 140 on the high pressure side. Then the double-acting valve 160 moves to the left in Figure 5 to seal the gate 140 of the chamber 130, and place the gate 138 in flow communication with the camera. It should also be noted that the hydraulic pressures of the hydraulic fluid in the gates 138 and 140 provide a hydrostatic bearing effect for balancing the axial thrust load generated in the transmission 10, and appearing in the sliding interconnection 0 between the plate. of gate 134 and the piston holder of pump 52, as described in my pending application cited with Serial Number (35-OR-949). Considering the output end of the transmission 5 10 seen in Figures 1 and 2, as noted above, the annular manifold block 58 surrounds the output shaft 16 in an axial position between the radial flange 170 of the carrier piston 56 of the motor and the output end part 60 of the output shaft. The radial face 171 of the end piece 60 is recessed to receive an exit gate plate 172, which is secured in place. Accordingly, the output gate plate 172 rotates with the output shaft 16 while, as noted above, the manifold block 58 is stationary, being grounded in the housing 12 by screws 59. The manifold block 58 includes a cylindrical core 180 with an annular cavity 182 machined on its outer peripheral surface, and an annular cavity 184 machined on the surface of its central aperture 185. An external jacket 186 is snapped around the peripheral surface of the core 180, to provide a radial seal for the outer cavity 182, and an inner sleeve 188 is snapped into the central opening 185 of the core, to serve as a radial seal for the internal cavity 184. A plurality of screw holes 189 are drilled into the ring 186, to receive the screws 59, which ground the piston carrier 56 of the engine and the manifold block 58 in the housing. The left face of the manifold core 180 is machined to provide an annular array of circular recesses 190 in a respective axial alignment with the annular array of the pistons 92 of the engine, and in a respective flow communication with the axial holes 192 in the poles piston assembly 98 motor. In the illustrated embodiment, the hydraulic motor unit 20 includes ten motor pistons 92 in a number equal to the number of pistons 76 of the pump, and consequently, ten recesses 190 are provided in the core of the manifold 180. As seen in FIG. Figures 2 and 6, an axial hole 194 is drilled through the manifold core 180 from each recess 190 to the right radial support face 196 of manifold block 58 (Figure 2). Then, as also seen in Figure 7, radially aligned with each hole 194, there is a pair of flanging axial holes 198 and 199 drilled from the support face 196 to a communication with the outer annular cavity 182 and the inner annular cavity. 184, respectively. Returning to Figure 6, a radially elongated groove 202 on the left radial face 203 of the manifold block 58 is cut at an angular position between an adjacent pair of recesses 190. The inner end of the groove 202 communicates with an axial bore 204 perforated through the piston carrier 56 of the motor, to a communication with the annular chamber 132, defined by the piston carrier of the motor and the spherical bearing 102 (Figure 1). The outer end of the groove 202 communicates with an axial hole 206 pierced through the outer jacket 186 to a gate 208 in the housing 12, which is connected in the hydraulic circuit of Figure 10. Referring together to Figures 2 and 6, a second radial groove 210 is cut in the left radial face of the manifold block 58, and extends between another pair of adjacent recesses 190, from an inner end communicating with an axial hole 212 punched in the inner annular cavity. 184, and an outer end communicating with an axial hole 214 punched through the outer jacket 186 to a second gate of the housing 216. Finally, as seen in the fragmentary view of Figure 8, an opening 218 is machined in the outer jacket 176, to provide communication between the outer annular cavity 182 and a third housing gate 220, angularly spaced apart from the doors of the housing 208 and 216. Now, considering Figure 1 in conjunction with Figure 9, in a manner similar to the inlet gate plate 134, a pair of circumferentially elongated kidney gates 222 and 224 are provided in the output gate plate. 172. However, in the case of the output gate plate 172, it is seen that the gates 222 and 224 are placed in a radially offset relationship. Accordingly, as seen in Figure 1, the radially outer gate 224 provides fluid communication between the orifices through the manifold 194 and the holes 198 toward the outer annular cavity 182, while the radially internal slot 222 provides fluid communication between the through holes of the manifold 194 and the orifices 199 towards the inner annular cavity 184. It will be appreciated that since the driver plate 22 and the outlet gate plate 172 rotate in unison in relation to the stationary motor unit 20, the plate gate 172 provides continuous fluid communication between the annular cavity 184 and the cylinders of the motor 104 (via the orifices 199 to the cavity 184, the holes through the manifold 194, and the orifices of the piston post of the pump 192) , suffering a volumetric contraction on the pumping side (high pressure) of the hydraulic motor unit 20. In a similar manner, the pl the output gate 172 provides continuous communication between the annular cavity 182 and the cylinders of the motor 104 (through the holes 198 towards the cavity 182, the holes through the manifold 194, and the holes of the post 192), undergoing an expansion volumetric on the suction side (low pressure) of the hydraulic motor unit 20. Accordingly, the hydraulic fluid in the annular cavity 184 assumes a high fluid pressure corresponding to the average fluid pressures in the rotating motor cylinders on the pumping side (high pressure), and the hydraulic fluid in the annular cavity 182 assumes a low fluid pressure corresponding to the average fluid pressures in the cylinders of the motor that rotate on the suction side (low pressure) of the hydraulic motor unit 20. As described above, the high pressure hydraulic fluid in the cavity 184 communicates with the housing gate 216 (Figure 2), while after the low pressure hydraulic fluid in the cavity 182 communicates with the gate 220 (Figure 8). It will also be noted that, as in the case of the inlet gate plate 134, the fluid pressure in the gates 212 and 214 of the outlet gate plate 172 provides a hydrostatic bearing effect in the interconnection of the gate plate. rotary output and the manifold block 58, to balance the axial thrust loads of the output end of the transmission 10. Since a detailed description of the operation of the transmission 10 can be had by referring to my TCP request, the Operational description is merely summarized herein for brevity. When the torque is applied to the input shaft 14 by a primary motor, the sweep pump 42 is driven together with the pump unit 18 by means of a ring gear 74 to introduce filling fluid into the cylinders of the pump and motor 90 and 104 by means of gate 220 of the >; housing, and the internal fluid passages described above. When the angular position of the entrance face 110 of the drive plate (Figure 1) is essentially perpendicular to the axis of the exit arrow 25, the cylinder block 88 of the pump rotates in a circular path without an axial component of movement and , therefore, there is no pumping of the hydraulic fluid. This is the neutral position of the transmission ratio, as noted above. When it is desired to apply a torque to a load connected to the output shaft 16, the drive plate 22 is pivoted in the clockwise direction, the axial positions of the ball bearings 86 and 102 together moving to the right, and the rotating shaft of the drive plate precesses to a new position. With the input face 110 of the drive plate 22 now at an oblique angle relative to the axis of the output shaft 25, now the rotation of the cylinder block 88 of the pump is around a precessed angularly offset axis of the shaft. the output arrow 25. Note that the rotary shaft of the cylinder block 100 of the motor also precesses to a new position dictated by the output side 112 of the drive plate. Accordingly, the cylinders 90 of the pump reciprocate axially with respect to the pistons 76 of the pump, thereby presenting the hydraulic fluid in the cylinders of the pump, and pumping the pressurized fluid through the openings 115 of the cylinders, the kidney-shaped grooves 114 (Figure 3), and the openings of the cylinders 116 of the engine. The torque exerted on the inner face 110 of the drive plate 22 by the rotating face of the cylinder block 88 of the pump, constitutes a mechanical component of the input torque applied to the output shaft 16 by means of the plate motor. This mechanical torque component is essentially zero when the input face 110 of the drive plate is perpendicular to the axis of the output shaft 25, and is gradually increased to 100% of the output torque when the face output 112 of the drive plate is perpendicular to the axis 25. This is because, with the output side of the drive plate perpendicular to the axis of the output shaft, there is no pumping action of the pistons 92 of the motor in the cylinders 104 of the motor and, consequently, there is no fluid outlet from the motor unit 20. Accordingly, the pump unit 18 and the motor plate 22 are essentially hydraulically secured without a relative movement between the rotating cylinder block 88 of the pump and the drive plate 22. Accordingly, the ratio of 1: 1 transmissions with a direct mechanical transmission of the torque from the input shaft 14 to the output shaft 16. In the intermediate ribs of the drive plate 22, the hydraulic fluid pressurized by the pump unit 18 is pumped through the openings 115 of the pump cylinders, the kidney-shaped grooves 114 of the drive plate, and the openings 116 of the cylinders of the engine, to pressurize the hydraulic fluid in the cylinders of the engine 104 of the cylinder block 100 of the engine. The pressurized fluid in the cylinders of the engine 104 exerts an axial force against the axially facing internal surfaces of the cylinder block 100 of the engine, which in turn is exerted on the exit face 112 of the drive plate 22. Therefore, a torque component is imparted to the drive plate, which is approximately equal to the tangent of the angle of the drive plate relative to the axis of the output shaft by the axial force exerted by the cylinder block 100 of the motor on the drive plate 22. A third torque component exerted on the drive plate 22 is a pure hydrostatic component, and is a function of the differential force created by the hydraulic pressure exerted on the circumferentially opposite end surfaces of the grooves 114 ( Figure 3), which, as noted above, are from different areas. This third torque component constitutes approximately 85 percent of the torque transmitted through the transmission 10 at the intermediate transmission ratios between the neutral and 1: 1.

It will be appreciated that, at transmission ratios other than the neutral, while the cylinders 90 of the pump are rotating in the "uphill" direction from the thinnest point of the drive plate 22 to the thickest point, 5 the hydraulic fluid in the These cylinders are being pressurized. Consequently, this is the pumping or high-pressure side of the drive plate, as noted above. Then, on the diametrically opposite side of the drive plate, the cylinders 90 of the pump rotate in the "downhill" direction from the thickest point of the drive plate to the thinnest point. Then, this is the suction or low pressure side of the motor plate 22, during which the hydraulic fluid is transferred back to the cylinders 90 of the pump from the cylinders 104 of the motor. 15 Turning to the hydraulic circuit of Figure 10, the hydraulic fluid is pumped from the sump 44 by the sweeping pump 42 through a filter 230 and a fluid line 232 to the housing gate 220, to introduce hydraulic filling fluid at low pressure in the pump unit 18 and in the motor unit 20. An energy storage accumulator 234 is charged by the output of the scavenging pump from the filter 230 through a fluid line 236 and a valve load, generally indicated at 238. This loading valve includes a check valve 240 that opens to feed hydraulic fluid to the accumulator 234, unless the accumulator pressure exceeds the pump outlet pressure. In this case, an adjustable pressure relief valve 242 is opened, and the hydraulic fluid from line 236 is diverted to a return fluid line 244 leading back to the sump 44 through a second release valve. pressure 246 and a cooler 248. The pressure release valve 246 acts to reduce the pressure in the fluid line 236, /. when it is diverted to the fluid line 244, to allow Id that the sweep pump 42 work at a low pressure and feed the internal lubrication passages (not shown) by means of the fluid line 232. The accumulator 234 serves the purpose of storing energy, to ensure that it is always available a suitable hydraulic pressure for changing the transmission ratio in the absence of a suitable hydraulic fluid pressure at the outlet of the sweep pump 42. Accordingly, the accumulator 234 is connected through a fluid line 250 and a valve check 252 with the 0 gate 220. Therefore, there is hydraulic pressure available to change the transmission ratio in the event that the primary motor stops applying input torque to the input shaft 14. As a protective measure of the transmission, a pressure relief valve 5 254 (not shown in Figure 1) is incorporated in the drive plate 22, between the high and low pressure sides of the drive plate, in the manner described in my application of the aforementioned TCP , to prevent the pressure differential between the high and low pressure sides of the drive plate from exceeding the design limits. Although not shown, it will be appreciated that the hydraulic circuit of the transmission may also include an accumulator for the storage of high pressure energy for subsequent recovery to drive the input shaft and / or the output shaft in the manner described in my application. pending application with Serial Number (35-OR-949) cited. The reference numerals 86 and 130 of Figure 10 represent the spherical bearing and the annular chamber similarly referenced, respectively, in Figures 1 and 2. In a similar manner, the reference numerals 102 and 132 schematically represent the spherical value and the annular chamber similarly referenced in Figures 1 and 2. Line 260 of Figure 10 represents the fluid connection of chamber 130 to the low pressure side of pump unit 18. Still referring to Figure 10, a ratio change control valve 262 includes an outlet connected by a fluid line 264 to the housing gate 208, which, as described above, is in fluid connection with the annular chamber 132, as represented by the line 266. The control valve 262 includes as an inlet, a return fluid line 268 that leads back to the sump 44 through the cooler 248 and, therefore, is at atmospheric pressure. A second control valve inlet is a low pressure fluid inlet from the housing gate 220 via the fluid line 270, while the third inlet is a high pressure fluid inlet from the housing gate 216 by means of the fluid line 272. When it is desired to increase the transmission ratio (pivoting of the motor plate in the clockwise direction), the control valve 262 is positioned to vent the chamber 132 to atmospheric pressure by means of of the fluid line 268, as represented by the dotted arrow 262c. As a result, the fluid pressure in the chamber 130 exceeds the fluid pressure in the chamber 132. The volume of the chamber 130 expands, as the volume of the chamber 132 contracts, and the spherical bearings move axially to the right to pivot the drive plate 22 in the clockwise direction. Again, when the desired higher transmission ratio is reached, the control valve is repositioned to bring the chamber into fluid communication with the housing gate 220, thereby restoring a balance of the fluid pressure in the chambers 130 and 132 to establish the highest transmission ratio.

In operation, to establish a desired transmission ratio (drive plate angle), the control valve 262 is in the position illustrated in Figure 10, with the gate 220 of the low pressure housing in fluid communication with the chamber 132, as indicated by the solid line arrow 262a. Since the low fluid pressure in the housing damper 220 is essentially equal to the fluid pressure in the low pressure side of the pump unit 18 to which the fluid in the chamber 130 is pressurized, the fluid pressures in both chambers they are the same. Consequently, the axial positions of the spherical bearings are kept uniform to maintain a particular angle of the drive plate. Note that the axial forces on the spherical bearings 86 and 102 are in opposite directions to properly compress the faces of the cylinder block 88 of the pump and cylinder block 100 of the motor against the inner face 110 and the outlet face 112 of the drive plate 22. When it is desired to decrease the transmission ratio (pivoting of the drive plate 22 in the counterclockwise direction), the control valve 262 is positioned to put the chamber 132 in fluid flow communication with the gate 216 of the high pressure housing, as indicated by the dotted arrow 262b. The fluid pressure in the chamber 132 rapidly exceeds the fluid pressure in the chamber 130, and the volume of the chamber 132 expands as the volume of the chamber 130 contracts. Therefore, the spherical bearings 86 and 102 move to the left to pivot the drive plate 22 in the counterclockwise direction, as seen in Figures 1 and 2. When the desired angle of the drive plate is reached (lowest gear ratio) , the control valve 262 is repositioned to place the chamber 132 in fluid communication with the gate 220 of the low pressure housing (position of the solid arrow 262a), and a balance is restored in the fluid pressures in the chambers 130 and 132 to maintain the axial positions of the spherical bearing changed to the left and, consequently, to establish the lowest transmission ratio. When it is desired to increase the transmission ratio (pivoting of the drive plate in the clockwise direction), the control valve 262 is positioned to vent the chamber 132 to atmospheric pressure by means of the fluid line 268, as it is represented by the dotted arrow 262s. As a result, the fluid pressure in the chamber 130 exceeds the fluid pressure in the chamber 132. The volume of the chamber 130 expands as the volume of the chamber 132 contracts, and the spherical bearings move axially. to the right to pivot the drive plate 22 in the clockwise direction.

Again, when the desired higher transmission ratio is reached, the control valve is repositioned to bring the chamber into fluid communication with the gate 220 of the housing, thereby restoring a balance 5 of the fluid pressure in the cameras 130 and 132 to establish the highest transmission ratio. From the above description, it is seen that the present invention provides a hydrostatic transmission - - infinitely variable of the type described in my application for TCP cited, which provides advantages of compact size, fewer parts and reduced manufacturing costs. The involvement of spherical bearings in the design of the ratio controller provides a highly efficient and effective approach to changing the angle of the drive plate. Those skilled in the art will be able to see that various modifications and variations can be made to the apparatus of the present invention without departing from the spirit of the invention. Accordingly, it is intended that the present invention cover the modifications and variations thereof, given that they fall within the spirit of the appended claims and their equivalence.

Claims (20)

1. A continuously variable hydrostatic transmission, which comprises, in combination: a housing; an input arrow resting on the housing to receive a torque from a primary motor; , - a pump unit including a first carrier driven by the input shaft, and mounting an annular array of pistons of the pump, and a first cylinder block providing an annular arrangement of the cylinders of the pump for receiving respectively the pistons of the pump; 5 an engine unit including a second carrier fixed to the housing, and mounting an annular array of engine pistons, and a second cylinder block providing an annular array of engine cylinders to respectively receive the engine pistons; 0 an output arrow supported on the housing and adapted for a pulse connection with a load; an annular drive plate surrounding the output shaft, and having an inlet face and an outlet face configured at an acute angle, one in relation to the other, confronting the inlet face to the first cylinder block, and confronting the outlet face to the second cylinder block, the drive plate further including slots that accommodate the flow of fluid pumped between the cylinders of the pump and the cylinders of the engine through openings in the first and second cylinder blocks; a connector that pivotably couples the drive plate with the output shaft in a coupled torque relationship; and a ratio controller that selectively exerts coordinate axial forces on the first and second cylinder blocks, to set adjustable an angle of the drive plate relative to an output shaft arrow in accordance with a desired speed ratio between the input and output arrows. The transmission defined in claim 1, wherein the pump unit further includes a first spherical bearing that mounts to the first cylinder block relative to the first carrier, and the motor unit further includes a second spherical bearing that assembles the second cylinder block relative to the second carrier, and the ratio controller includes a defined circuit which communicates with the first and second spherical bearings to exert hydraulic forces to adjustably establish the axial positions of the first and second spherical bearings in relation to the output arrow, and thus exert the coordinated forces on the first and second cylinder blocks. The transmission defined in claim 1, wherein the connector includes a hub fixed on the output shaft, and an arm that extends radially from the hub, and has a free end pivotally connected to the motor plate. The transmission defined in claim 3, wherein the connector further includes a bolt oriented transversely to the axis of the output shaft and pivotally interconnecting the free end of the arm and the drive plate. The transmission defined in claim 4, wherein the pin is orthogonally oriented to the axis of the output shaft in a position generally between the input and output faces of the drive plate. The transmission defined in claim 4, wherein the position of the bolt is offset from the axis of the output shaft by a distance approximately equal to a radius of a circle conforming to the positions of at least one of the annular arrays of the cylinders of the pump and the motor. The transmission defined in claim 2, wherein: the first spherical bearing is mounted by the first carrier for relative sliding axial movement; the first spherical bearing and the first carrier are configured to define a first annular chamber having a volume determined by an axial position of the first spherical bearing; and the second spherical bearing is mounted on the second carrier for a relative sliding axial movement; the second spherical bearing and the second carrier are configured to define a second annular chamber having a volume defined by an axial position of the second spherical bearing; the ratio controller operating to control the relative fluid pressures in the first and second chambers, to change their volumes, and thus adjust the axial positions of the first and second incident spherical bearings to exert coordinated axial force on the first and second cylinder blocks. The transmission defined in claim 7, wherein the ratio control includes: "a first fluid circuit that continuously connects the first chamber with a low pressure side of the pump unit to maintain the fluid pressure in the first chamber in a control fluid pressure; a second fluid circuit communicating continuously with a low pressure side of the motor unit; a third fluid circuit communicating continuously with a high pressure side of the motor unit; a fourth fluid circuit connected to the second chamber; and an operable control valve for: connecting the fourth fluid circuit with the second fluid circuit, to create a fluid pressure in the second chamber that balances the control fluid pressure in the first chamber, and thereby maintain the axial positions of the first and spherical bearings; connecting the fourth fluid circuit with the third fluid circuit, to create a fluid pressure in the second chamber greater than the control fluid pressure in the first chamber, and thereby expand the volume of the second chamber, while the volume of the first chamber is contracted, to jointly move the axial positions of the first and second spherical bearings in the first direction; and venting the fourth fluid circuit to a lower pressure lower than the control pressure, to contract the volume of the second chamber, while expanding the volume of the first chamber, to jointly move the axial positions of the first and second bearings spherical in a second direction opposite to the first direction. The transmission defined in claim 8, wherein the pump unit includes first posts that mount the pistons of the pump to the first carrier, the first poles having holes included in the first fluid circuit to provide fluid communication between the cylinders of the pump on the low pressure side of the pump unit and the first chamber. The transmission defined in claim 9, wherein the motor unit includes second posts that mount the pistons of the motor to the second carrier, the second posts having pluralities spaced apart from the holes of the second posts included in the second and third circuits of fluid, to provide respective fluid communication between the cylinders of the motor on the low and high pressure sides of the motor unit and the control valve. The transmission defined in claim 9, wherein the first fluid circuit includes: a first gate plate positioned between the radial flange portions of the entry shaft and the first carrier, the first gate plate being fixed to the arrow of entry, and that includes a first gate in fluid communication with the holes of the first posts on the low pressure side of the pump unit, and a second gate in fluid communication with the holes of the first posts on one side high pressure pump unit; and a double acting valve, in fluid connection between the first and second gates, which operates to continuously connect the first chamber in fluid communication with the low pressure side of the pump unit. 1

2. The transmission defined in the claim 11, wherein the motor unit includes second poles that mount the pistons of the motor to the second carrier, the second poles having separate pluralities of holes from the holes of the second poles included in the second and third fluid circuits, to provide a communication of respective fluid between the cylinders of the motor of the low and high pressure sides of the motor unit and the control valve. 1

3. The transmission defined in the claim 12, which further includes: an annular manifold block placed between the radial flange portions of the second carrier and the exit arrow, the manifold block being fixed to the housing, and including a plurality of axially traversed holes in respective fluid communication with the holes of the second poles, a first annular cavity, and a second annular cavity; a second gate plate positioned between the manifold block and the flange portion of the exit arrow, the second gate plate being fixed to the flange portion of the exit arrow, and having a first gate included in the second circuit of fluid to provide fluid communication between the cylinders of the engine on the low pressure side of the engine unit and the first cavity, and having a second gate included in the third fluid circuit to provide fluid communication between the cylinders of the motor on the high pressure side of the motor unit and the second cavity; a first gate of the housing in fluid communication with the first cavity, and connected to the control valve; a second gate of the housing in fluid communication with the second cavity, and connected to the control valve; a third housing gate in fluid communication with the second chamber through a first radial surface groove in the manifold block and an axial hole in the second carrier, the third housing door being connected to the control valve. 1

4. The transmission defined in the claim 13, wherein the second cavity is provided in a radial internal portion of the manifold block, the fluid communication being between the second housing gate and the second cavity provided by a second radial surface groove in the manifold block. 1

5. A continuously variable hydrostatic transmission 5, which comprises, in combination: a housing: an input shaft supported on the housing to receive a torque from a primary motor; a pump unit including a first carrier driven by the input shaft, and mounting an annular array of pistons of the pump, and a first cylinder block providing an annular arrangement of the cylinders of the pump for receive respectively the pistons of the pump; 5 an engine unit including a second carrier fixed to the housing, and mounting an annular array of engine pistons, and a second cylinder block providing an annular array of engine cylinders for respectively receiving the engine pistons; 0 an output arrow supported on the housing and adapted for a pulse connection with a load; an annular drive plate surrounding the output shaft, and having an inlet face and an outlet face configured at an acute angle, one in relation to the other, confronting the inlet face to the first cylinder block, and confronting the outlet face to the second cylinder block, the drive plate further including slots that accommodate the flow of fluid pumped between the cylinders of the pump and the cylinders of the engine through openings in the first and second cylinder blocks; a connector that pivotably couples the drive plate with the output shaft in a coupled torque relationship; a ratio controller for adjusting an angle of the drive plate relative to an output shaft axis according to a desired speed ratio between the input and output arrows; an annular manifold block and an annular gate plate placed in a juxtaposed relation between the radial flange portions of the second carrier and the exit arrow, the manifold block being fixed to the housing, and the gate plate being fixed to the exit arrow , and including first and second gates, including the manifold block: axial traversed holes in respective fluid communication with the cylinders of the motor through the holes of the poles that mount the pistons of the pump and the first and second grooves of the pump. the gate plate; a first annular cavity in fluid communication with the first slot of the gate plate and those of the cylinders of the motor on a low pressure side of the motor unit; and a second annular cavity in fluid communication with the second slot of the gate plate and those of the cylinders of the motor on a high pressure side of the motor unit; at least one of the first and second cavities is connected in a hydraulic fluid circuit with the ratio controller. 1

6. The transmission defined in the claim 15, which further includes a scavenger pump connected in the hydraulic fluid circuit for supplying hydraulic fluid at low pressure to the first annular cavity. 1

7. The transmission defined in the claim 16, wherein a radial interconnection between the manifold block and the gate plate provides a hydraulic thrust bearing to balance the axial bushing load of the transmission appearing in the radial interconnection. The transmission defined in claim 16, wherein the pump unit further includes a first spherical bearing that mounts to the first cylinder block relative to the first carrier, and the motor unit further includes a second spherical bearing that mounts the second cylinder block in relation to the second carrier, the ratio controller being operatively connected to jointly move the axial positions of the first and second spherical bearings, whereby forces are exerted on the drive plate by means of the first and second blocks of cylinders to change the angle of the drive plate. The transmission defined in claim 15, wherein the connector includes a hub fixed on the output shaft and an arm extending radially from the hub, and having a free end pivotally connected to the motor plate on an axis of pivot oriented transversely to the axis of the output shaft, the pivot axis being radially offset from the axis of the output shaft by a distance approximately equal to a radius of a circle conforming to the positions of the annular arrangements of the cylinders of the shaft. pump and motor. 20. A continuously variable hydrostatic transmission comprising, in combination: a housing; an input arrow resting on the housing to receive a torque from a primary motor; a pump unit including a first carrier driven by the inlet arrow, and mounting an annular piston array of the pump, and a first cylinder block that provides an annular arrangement of the pump cylinders to respectively receive the pistons of the bomb; an engine unit including a second carrier fixed to the housing, and mounting an annular array of engine pistons, and a second cylinder block providing an annular array of engine cylinders to respectively receive the engine pistons; an output arrow resting on the housing and adapted for a pulse connection with a load; an annular drive plate surrounding the output shaft, and having an inlet face and an outlet face configured at an acute angle, one in relation to the other, confronting the entrance face to the first cylinder block, and confronting the outlet face to the second cylinder block, the driving plate further including slots which accommodate the flow of fluid pumped between the cylinders of the pump and the cylinders of the engine through openings in the first and second cylinder blocks; a connector that pivotably couples the drive plate with the output shaft in a coupled torque relationship; the connector including a hub fixed on the output shaft and an arm extending radially from the hub, and having a free end pivotally connected to the drive plate on a pivot axis oriented transversely to the output shaft, the shaft being of pivot radially offset from the axis of the output shaft by a distance substantially equal to a radius of a circle conforming to the positions of the annular arrays of the cylinders of the pump and the motor; and a ratio controller for pivoting the drive plate about the pivot axis to adjustably establish an angle of the drive plate relative to an output shaft axis in accordance with a desired speed ratio between the input and output arrows. departure.