CONTROL DEVICES OF A HYDROSTATIC TRANSMISSION

Abstract: The invention refers to control devices applied in a hydrostatic transmission, which includes a motor pump (MP), a hydrostatic circuit (HC 1 and HC 2) and an impelling pump (IP), which is formed by a rotor (1), a stator (2) and a body (3); the fluid debit is infinitely variable and is obtained by the radial and variable decentralisation of the said stator (2), by means of the impulsion of the rods (A and B). The devices are constituted by pistons (4 and 5), which impel the rods (A and B), and are inserted in cylinders (6 and 7); by springs systems (9, 10 and 11), which regulate the position of the pistons and of the rods, and by a command formed by a valve (8), inserted in a vacuum circuit with ways (VI and V2), which communicate with the cylinder (7). Through way (VI) the vacuum effect acts on the piston (5), obtaining the decentralisation of the stator (2) in direction of the rod (A); the fluid pressure transmitted by the extension (HE) to the piston (4), regulates the debit of the impelling pump and the rotation speed of the motor pump, whose rotation direction is the same as the impelling pump, (FIG: 1). Through way (V2) the decentralisation of the stator (2) is obtained in the inverse direction to the rod (A), and the rotation direction of the motor pump is inverse of the r otation direction of the impelling pump, (FIG 2). When the command is not activated, no fluid impulsion is transmitted by the impelling pump and there is no rotation of the motor pump, (FIG. 3).

Description: CONTROL DEVICES OF A HYDROSTATIC TRANSMISSION DESCRIPTION Technical domain The present invention simplifies and renders practical the control of hydrostatic transmissions in which the pumps, with either impelling or motor functions, are preferably of the rotational type and of infinitely variable debit of fluid, so that the variation of the said debit may be automatic, according to the variation of the pressure in the fluid circuit of the transmission. Previous technique In the previous technique the debit variation is obtained by varying the amplitude of the piston course inside the cylinders recurring to the variable inclination of a plate acting in the piston base; the variation of the said inclination demands a great strength for it depends on the work pressures of the said pistons; as those pressures are very high, it is difficult to apply the means in order to obtain the progressive variation of the fluid debit. Explanation of the invention In a previous application, we developed a hydrostatic pump (IP), of infinitely variable debit, which includes a rotor (1), a stator (2) and a body (3); the infinitely variable debit is obtained by the radial and variable decentralisation of the said stator by means of the impulsion of the rods, (A) and (B). The different work pressures of the fluid, which act on each internal side of the stator, are compensated and balanced on the corresponding external side by equal fluid pressures transmitted to cameras; each one of the said cameras is contiguous to each one of the sides. A great advantage of the application of this method, is that the strength applied in the impulsion of said rods is small and independent from the work pressures of the fluid; this fact permits the application of the adequate devices, in order to be obtained an easy and safe control of the variation of the amplitude and of the direction of the decentralisation of the stator of a hydrostatic pump, either its function is impelling or motor. The said control devices of a hydrostatic transmission are constituted by pistons (4) and (5), which give impulse to the rods (A) and (B) and are inserted in cylinders (6) and (7); by systems of springs (9), (10) and (11), which regulate the position of the pistons and of the rods; and by a transmission control formed by a valve (8), inserted in a vacuum circuit with two ways (VI) and (V2), which communicate with the second cylinder (7). The application and the functioning of the said devices, are explained below with the help of the description of three illustrative examples, and without a limited character, of the conception and application of the said devices, which perform the present invention in the preferred form. Brief description of the drawings Fig. 1, represents in section the application of the control devices in a hydrostatic transmission, in which the decentralisation of the stator (2) is obtained in the direction of the rod (A); the motor pump (MP) has the same direction of the rotation of the impelling pump (IP). Fig. 2, represents in section the application, in which the decentralisation of the stator (2) is obtained in the inverse direction of the rod (A); the rotation direction of the motor pump is inverse of the impelling pump. Fig. 3, represents in section the application, in which the stator is in a centred position; no fluid impulsion is transmitted by the impelling pump and there is no rotation of the motor pump. Description of the preferred incorporation Considering the application of the control devices in a hydrostatic transmission of infinitely variable speed, which includes an impelling pump as the one described above (IP), associated with a motor pump (MP) by means of a fluid circuit (HC 1) and (HC 2), the said application is performed as follows: in the impelling pump (IP), the piston (4) is inserted in the first cylinder (6), it has a simple effect and impels the rod (A) through the top; its retrocession is obtained by means of a system of springs (9); the said cylinder communicates with the side (HC 1) of the hydrostatic circuit, by means of a hydrostatic extension (HE); the piston (5) is inserted in the second cylinder (7), it has a double effect and is fastened with the rod (B); its balance position is obtained by the joint action of the springs systems (10) and (11), and its impulsion is regulated by the transmission command; the regulation of the transmission command is obtained by the valve (8) regulation directing, through ways (VI) or (V2), the activation of the vacuum effect to the second cylinder (7), in order to obtain the impulsion of the respective piston (5), in the direction of the decentralisation of the stator, determined by the said command. Detailed description Figures 1, 2 and 3 of the drawings, show the functioning of a hydrostatic transmission of infinitely variable speed, in which the control devices are applied to an impelling pump (IP) of infinitely variable debit, as it was described above. In Fig. 1, the motor pump (MP) has the same rotation direction of the impelling pump (IP); the transmission command directs the activation of the vacuum effect through way (VI) to the second cylinder (7), in order to impel the piston (5) and the rod (B) which is fastened to it, in the direction of the rod (A); it is obtained the decentralisation of the stator of the impelling pump (IP) in the direction of the said rod (A); agreeing that the rotor rotation of the impelling pump (IP) is in the direction (C), the fluid is impelled by the said rotor in the direction from (F) to (G); it acts in the rotor of the motor pump (MP) in the direction from (L) to (K), and the rotation of its rotor is obtained in direction (D) equal to the direction (C), of the rotor rotation of the impelling pump. The debit variation of the impelling pump and the corresponding speed variation of the motor pump, are going to be explained as follows: - to an increase in resistance, which opposes to the rotor rotation of the motor pump, there is the correspondence of an increase in the normal work strength of the binary motor, which activates the rotor of the impelling pump; to the increase in the said strength there is the correspondence of an increase in the fluid pressure, on the side (HC 1) of the circuit of the hydrostatic transmission; by means of a hydrostatic extension (HE), the said pressure increase is transmitted to the first cylinder (6); the respective piston (4) impels the rod (A), in order to reduce the amplitude of the decentralisation of the stator, so that the balance level of the said normal work strength of the binary motor may be re-established; - to a decrease of the said resistance, there is the correspondence of a pressure decrease in the circuit (HC 1), transmitted by the extension (HE) to the cylinder (6); the springs system (9) performs the piston retrocession (4), and it is recovered the amplitude of the decentralisation of the stator referring to the anterior cycle; - in the impelling pump (IP), the amplitude of the decentralisation of the stator and the corresponding fluid debit, have a decreasing variation in relation to the increasing variation of said resistance, which opposes to the rotation of the motor pump (MP); - the rotation speed of the said motor pump, also has a decreasing variation, in relation to the increasing variation of the said resistance. In Fig. 2, the motor pump (MP) has the rotation direction inverse to the one of the impelling pump (IP); - the transmission command controls the activation of the vacuum effect through way (V2) to the second cylinder (7), in order to impel the piston (5) and the rod (B), which is fastened to it in the inverse direction to the one of the rod (A); it is obtained the decentralisation of the stator in the direction of the rod (B), inverse to the direction of the anterior decentralisation; - in the impelling pump (IP) the fluid circulates in the direction from (G) to (F) and in the motor pump (MP) from (K) to (L); the rotor rotation of the motor pump is in the direction (E), inverse to the direction (C) of the rotor rotation of the impelling pump. In Fig. 3, the motor pump has no rotation movement, though the rotation of the impelling pump is maintained; - the transmission command is not activated; the valve (8) is closed and no vacuum effect is transmitted; the stator (2) of the impelling pump (IP) is centred and balanced by the action of the springs systems (10) and (11); - no fluid impulsion is transmitted, regardless of the speed rotation of the said impelling pump. Several applications The control devices which were described with reference to their application to a hydrostatic transmission, which includes a motor pump, may be also applied to other types of hydrostatic transmissions, for example, replacing the motor pump by either static or linear movement hydrostatic devices. The said devices may be also applied to a motor pump or simultaneously to an impelling pump and a motor pump.

Claims: CLAIMS 1. Control devices of a hydrostatic transmission, the said transmission includes a motor pump (MP), a hydrostatic circuit (HC 1) and (HC 2) and an impelling pump (IP); the said impelling pump is formed by a rotor (1), a stator (2) and a body (3); the fluid debit is infinitely variable and is obtained by the radial and variable decentralisation of the said stator, by means of the impulsion of the rods (A) and (B); the said control devices are characterised by; it is obtained the variation of the direction and of the amplitude of the impulsion of the said rods (A) and (B), by means of pistons (4) and (5), inserted in cylinders (6) and (7) respectively; a first cylinder (6), communicates with the hydrostatic circuit (HC 1), by means of the extension (HE); a second cylinder (7), communicates with a vacuum circuit, which includes ways (VI) and (V2) and a valve (8), forming the transmission command; springs systems (9), (10) and (11), control the positions of the said pistons (4) and (5). 2. Control devices, according to claim 1, characterised by; the piston (4) of the first cylinder (6) has a simple effect, it impels the rod (A) through the top and its retrocession is obtained by means of the springs system (9). 3. Control devices, according to claim 1, characterised by; the piston (5) of the second cylinder (7) has a double effect, it is fastened whit the rod (B) and its balance position is obtained by the joint action of the springs systems (10) and (11). 4. Control devices, according to claims 1 and 2, characterised by; the variable pressure obtained on the side (HC 1) of the fluid circuit of the transmission, and produced by the variable resistance which opposes to the rotation of the motor pump (MP), is transmitted to the first cylinder (6) by the extension (HE) of the said fluid circuit. 5. Control devices, according to claim 4, characterised by; the said variable pressure transmitted to the first cylinder (6), acts in the respective piston (4); the said piston impels the rod (A), in order to obtain a decreasing variation of the amplitude of the decentralisation of the stator of the impelling pump (IP), in correspondence with the increasing variation of the said pressure. 6. Control devices, according to claims 1 and 3, characterised by; they include a transmission command formed by a valve (8) inserted in a vacuum circuit with ways (VI) and (V2), which communicate with the second cylinder (7). 7. Control devices, according to claim 6, characterised by; the regulation of the transmission command is performed by valve (8), directing through ways (VI) or (V2) the activation of the vacuum effect to the second cylinder (7), in order to obtain the impulsion of the respective piston (5), and the decentralisation of the stator (2), in the direction determined by the said command. 8. Control devices of a hydrostatic transmission, according to previous claims, characterised by; the transmission command drives the valve (8) and directs the activation of the vacuum effect in the direction of the way (VI), in order to be obtained: the decentralisation of the stator (2) in the direction of the rod (A); the rotation of the motor pump (MP) in the same rotation direction of the impelling pump (IP); the decreasing variation of the rotation speed of the said motor pump, in correspondence with the increasing variation of the resistance which opposes to its rotation, (FIG. 1); the said command drives the valve (8) and directs the activation of the vacuum effect in the direction of the way (V2), in order to be obtained: the decentralisation of the stator (2) in direction of the rod (B), inverse to the one of the rod (A); the rotation of the motor pump (MP) in the inverse direction to the rotation of the impelling pump (IP), (FIG. 2); the said command closes the valve (8), it does not activate the vacuum effect and it achieves the centralisation and balance of the stator (2), by the joint action of the springs systems (10) and (11), in order to be not transmitted any impulsion fluid, whatever the speed rotation of the impelling pump may be; the motor pump has no rotation movement, though the rotation of the impelling is maintained, (FIG: 3). 9. Control devices of a hydrostatic transmission, according to previous claims, characterised by; the impelling pump (IP) or the motor pump (MP), are replaced by static hydrostatic apparatus, or by hydrostatic apparatus of linear movement. 10. Control devices of a hydrostatic transmission, according to previous claims, characterised by; being applied identically to a motor pump (MP), or simultaneously to an impelling pump and a motor pump. AMENDED CLAIMS [received by the International Bureau on 25 May 2000 (25.05.00); original claim 1 amended ; remaining claims unchanged ; (2 pages)] 1. Control devices of a hydrostatic transmission, the said transmission includes a motor pump (MP), in communication whit an impelling pump (IP) by means of a fluid circuit (HC 1) and (HC 2); the said impelling pump is formed by a rotor (1) and a stator (2) contained inside a body (3); the fluid debit of the said impelling pump is infinitely variable, in accordance with the infinitely variable amplitude of the radial decentralisation of said stator (2), obtained by means of the impulsion of rods (A) and (B); the variable work pressures of the fluid which act in each internal side of the said stator (2), are compensated an balanced on the corresponding external side, by equal fluid, thus resulting to be small and independent from the said work pressures of the fluid, the needed force applied in the impulsion of said rods (A) and (B); the said control devices of a hydrostatic transmission are characterised by: - being associated and adapted with the characteristics of the said impelling pump (IP) and acting in accordance, thus being constituted a control system suited for said transmission in order to achieve the easy control of the variation of the amplitude of the impulsion of said rod (A), in accordance with the variation of the pressure built in the section of the fluid circuit of the transmission (HC 1); and so as to obtain the easy control of the variation of the direction of the impulsion of said rod (B), in accordance with the variation of the direction of the fluid circulation to be obtained in said transmission; - including a first cylinder (6), which communicates with the side (HC 1) of the hydrostatic circuit by means of the hydrostatic extension (HE); said first cylinder contains piston (4) which actuates on rod (A) in order to obtain the infinitely variable decentralisation of stator (2); including a second cylinder (7) which communicates with a vacuum feeding circuit, by means of the ways (VI) and (V2); said ways connected to a valve (8) which commands the direction of actuation of the vacuum; said second cylinder contains piston (5) fastened with rod (B), said rod acting in order to obtain the variation of the direction of the circulation of the fluid in said transmission (HC 1) and (HC 2); - including the spring systems (9), (10) and (11), of laminar type, whose pressure control the reciprocate position of pistons (4) and (5) and the reciprocate position of rods (A) and (B). 2. Control devices, according to claim 1, characterised by; the piston (4) of the first cylinder (6) has a simple effect, it impels the rod (A) through the top and its retrocession is obtained by means of the springs system (9). 3. Control devices, according to claim 1, characterised by; the piston (5) of the second cylinder (7) has a double effect, it is fastened with the rod (B) and its balance position is obtained by the joint action of the springs systems (10) and (11). 4. Control devices, according to claims 1 and 2, characterised by; the variable pressure obtained on the side (HC 1) of the fluid circuit of the transmission, and produced by the variable resistance which opposes to the rotation of the motor pump (MP), is transmitted to the first cylinder (6) by the extension (HE) of the said fluid circuit. 5. Control devices, according to claim 4, characterised by; the said variable pressure transmitted to the first cylinder (6), acts in the respective piston (4); the said piston impels the rod (A), in order to obtain a decreasing variation of the amplitude of the decentralisation of the stator of the impelling pump (IP), in correspondence with the increasing variation of the said pressure. 6. Control devices, according to claims 1 and 3, characterised by; they include a transmission command formed by a valve (8) inserted in a vacuum circuit with ways (VI) and (V2), which communicate with the second cylinder (7). 7. Control devices, according to claim 6, characterised by; the regulation of the transmission command is performed by valve (8), directing through ways (VI) or (V2) the activation of the vacuum effect to the second cylinder (7), in order to obtain the impulsion of the respective piston (5), and the decentralisation of the stator (2), in the direction determined by the said command. 8. Control devices of a hydrostatic transmission, according to previous claims, characterised by; the transmission command drives the valve (8) and directs the activation of the vacuum effect in the direction of the way (VI), in order to be obtained: the decentralisation of the stator (2) in the direction of the rod (A); the rotation of the motor pump (MP) in the same rotation direction of the impelling pump (IP); the decreasing variation of the rotation speed of the said motor pump, in correspondence with the increasing variation of the resistance which opposes to its rotation, (FIG. 1); the said command drives the valve (8) and directs the activation of the vacuum effect in the direction of the way (V2), in order to be obtained: the decentralisation of the stator (2) in direction of the rod (B), inverse to the one of the rod (A); the rotation of the motor pump (MP) in the inverse direction to the rotation of the impelling pump (IP), (FIG. 2); the said command closes the valve (8), it does not activate the vacuum effect and it achieves the centralisation and balance of the stator (2), by the joint action of the springs systems (10) and (11), in order to be not transmitted any impulsion fluid, whatever the speed rotation of the impelling pump may be; the motor pump has no rotation movement, though the rotation of the impelling is maintained, (FIG: 3). 9. Control devices of a hydrostatic transmission, according to previous claims, characterised by; the impelling pump (IP) or the motor pump (MP), are replaced by static hydrostatic apparatus, or by hydrostatic apparatus of linear movement. 10. Control devices of a hydrostatic transmission, according to previous claims, characterised by; being applied identically to a motor pump (MP), or simultaneously to an impelling pump and a motor pump. STATEMENT UNDER ARTICLE 19 Claims 1 — It has been amended so as to characterise in a more clear way the specific working mode of the different devices, associated and adapted to the characteristics of impelling pump (IP) so as to obtain a system for the control of a hydrostatic transmission in the context which includes the said impelling pump (IP), the said system for the control of a hydrostatic transmission which is the object of the present application.

Inventors: BAPTISTA FERNANDO AUGUSTO, PEREIRA DIAS BAPTISTA JOAO MAN, BAPTISTA, FERNANDO, AUGUSTO, PEREIRA DIAS BAPTISTA, JOAO, MANUEL
Applicants: BAPTISTA FERNANDO AUGUSTO, PEREIRA DIAS BAPTISTA JOAO MAN, BAPTISTA, FERNANDO, AUGUSTO, PEREIRA DIAS BAPTISTA, JOAO, MANUEL
Application year: 1999
Main classification: F16H39
IPC codes: F04C11, F04C14, F16H61