초록 ▼

A hydraulic circuit including a first motor set, and a second motor set for driving vehicle-moving means situated one behind the other. The circuit has first, second, third, and fourth main ducts for feeding the motor sets in parallel. The device includes a selector suitable for taking up a first st

A hydraulic circuit including a first motor set, and a second motor set for driving vehicle-moving means situated one behind the other. The circuit has first, second, third, and fourth main ducts for feeding the motor sets in parallel. The device includes a selector suitable for taking up a first stable position making the feeding in parallel possible by interconnecting in pairs the feed and discharge main ducts, and for taking up a second stable position in which one of the motor sets is inactive because one of the main ducts is connected to one of main ducts of the other set. Between the stable positions, the selector can take up a temporary position, in which all four main ducts are interconnected. At least while the selector is moving in one direction between its two stable positions, the temporary position is sustained in an intermediate stage during which at least one of the interconnections between the main ducts of the first and second motor sets is constricted.

대표청구항 ▼

The invention claimed is: 1. A device for selecting the overall cubic capacity of a hydraulic circuit comprising: a first motor set comprising at least one first hydraulic motor for driving first vehicle-moving means for moving a vehicle, and a second motor set comprising at least one second hydrau

The invention claimed is: 1. A device for selecting the overall cubic capacity of a hydraulic circuit comprising: a first motor set comprising at least one first hydraulic motor for driving first vehicle-moving means for moving a vehicle, and a second motor set comprising at least one second hydraulic motor for driving second vehicle-moving means for moving the vehicle, said first and second vehicle-moving means being situated one behind the other in a direction in which the vehicle moves, the circuit further comprising first and second main ducts for the first motor set, and third and fourth main ducts for the second motor set, the first and third main ducts and the second and fourth main ducts being suitable for being connected in respective pairs to respective ones of two orifices of a pump for feeding and discharging the motor sets in parallel, the device comprising a selector suitable for taking up a first stable position corresponding to a first configuration of the selector device, in which configuration the third and fourth main ducts are connected to respective ones of the orifices of the pump, and said third and fourth ducts are isolated from each other so that the second motor set is active, and for taking up a second stable position corresponding to a second configuration of the selector device, in which configuration one of the first and second main ducts is connected to the third and fourth main ducts, so that the second motor set is inactive, the selector being such that, while the selector is moving between said stable positions, a temporary situation exists in which the first, second, third, and fourth ducts are interconnected; said device further comprising means serving, at least while the selector is moving in a first direction between its first and second stable positions, to sustain said temporary situation for a period of time in an intermediate stage during which an interconnection between the third and fourth main ducts and an interconnection between at least one of the first and second main ducts and at least one of the third and fourth main ducts are constricted. 2. A device according to claim 1, wherein, during the intermediate stage, the interconnection between the third and fourth main ducts and the interconnection between at least one of the first and second main ducts and at least one of the third and fourth main ducts have constricted cross-sections that are different. 3. A device according claim 1 wherein the cross-section of at least one of the constricted interconnection between the third and fourth main ducts and the constricted interconnection between at least one of the first and second main ducts and at least one of the third and fourth main ducts remains substantially constant during the intermediate stage. 4. A device according to claim 1 wherein the cross-section of at least one of the constricted interconnection between the third and fourth main ducts and the constricted interconnection between at least one of the first and second ducts and at least one of the third and main ducts varies during the intermediate stage. 5. A device according to claim 1, wherein the selector is a valve having at least three ports, comprising first, second, and third ports connected respectively to the first, to the second, and to the third main ducts, and the device further comprises means for interconnecting the second and the fourth main duct, the first and second main ducts being respectively connected to the first and to the second orifices of the pump. 6. A device according to claim 5, wherein the fourth main duct and the second main duct are interconnected via an interconnection duct that is external to the selector, and, when the selector is in the first stable position, the first and third ports are interconnected while being isolated from the second port, and, when the selector is in the second stable position, the second and third ports are interconnected while being isolated from the first port, whereas, in the temporary situation, the first and second ports are interconnected and the second and third ports are interconnected. 7. A device according to claim 5, wherein the valve has a fourth port connected to the fourth main duct and, when the selector is in the first stable position, the first and second ports and the second and fourth ports are interconnected in respective pairs, and, when the selector is in the second stable position, the third and fourth ports are interconnected and are connected to one of the first and second ports while being isolated from the other of the first and second ports, whereas, in the temporary situation, the first and second ports are connected via a first passage having a first constriction, the second and fourth ports are interconnected via a second passage having a second constriction, and an additional passage having an additional constriction exits between the first and second ports or between the third and fourth ports. 8. A device according to, claim 1 wherein, when in its second stable position, the selector enables connection of one of the first and second main ducts that is at the lower pressure to the third and fourth main ducts. 9. A device according to claim 8, wherein the selector is a valve that has first, second, third, and fourth ports, connected to respective ones of the first, second, third, and fourth main ducts, and said valve has a shuttle suitable, when said selector is in the second stable position, for putting the third and fourth ports into communication with that one of the first and second ports that is at the lower pressure. 10. A device according claim 1, further comprising means for causing the selector to move between said stable positions, during which movement said temporary situation exists, which control means are suitable for causing a fast movement first step to take place between the initial stable position of the selector and a position corresponding to the beginning of the intermediate stage, and for causing a braked movement step to take place during which the intermediate stage takes place. 11. A device according to claim 10, wherein the control means are also suitable for causing another fast movement step to take place towards the other stable position, at the end of the intermediate stage. 12. A device according to claim 1, wherein the selector is a valve comprising a slide mounted to move in a bore the slide being suitable for taking up two opposite positions corresponding to respective ones of the first and second stable positions of the selector, and, while the slide is moving between these two opposite positions, being suitable for taking up an intermediate position corresponding to said temporary situation. 13. A device according to claim 12, wherein the control means for causing the slide to move comprise a first control chamber formed in the bore, at one end of the slide, and a second control chamber formed in a cavity in said end of the slide and separated from the first chamber by a control piston disposed in said cavity, the first control chamber being suitable for being connected to first command means so as to enable the assembly made up of the slide and of the control piston to move in a first direction in a fast movement first step at the end of which the control piston finds itself in an end position, and the second control chamber being suitable for being connected to second command means so as to enable the slide to move relative to the control piston in the first direction, in a slow movement second step. 14. A device according to claim 13, wherein the control means for causing the slide to move further comprise a third control chamber for acting with said first and second control chambers to cause the slide to move in two opposite directions. 15. A device according to claim 1, further comprising means for causing the selector to move between said stable positions, during which movement said temporary situation exists, which means are suitable for servo-controlling a variable that is representative of operation of the vehicle to a set point by causing the selector to move in controlled manner. 16. A device according to claim 15, wherein the representative variable is determined on the basis of at least one of the parameters constituted by the pressure in at least one of the main ducts, the flow rate in at least one of the main ducts, the number of revolutions at the outlet of at least one of the motors, the output speed of at least one of the motors, the speed of the vehicle, position relative to a target, distance relative to a target, the acceleration or the deceleration of the vehicle, the acceleration or the deceleration of at least one of the motors, an operating parameter of the pump, the power being consumed, an operating parameter of an auxiliary motor driving said pump, and an operating parameter of a tool fed hydraulically from the circuit. 17. A device according to claim 1, wherein the control means for causing the selector to move further comprise electronic control means, and said device further comprises means for measuring the value of at least one critical parameter, for computing the value of the representative variable, and for causing the selector to move from one to the other of its stable positions as a function of the value of the computed representative variable. 18. A hydraulic circuit comprising a first motor set comprising at least one first hydraulic motor for driving first vehicle-moving means for moving a vehicle, and a second motor set comprising at least one second hydraulic motor for driving second vehicle-moving means for moving the vehicle, said first and second vehicle-moving means being situated one behind the other in a direction in which the vehicle moves, the circuit further comprising first and second main ducts for the first motor set, and third and fourth main ducts for the second motor set, the first and third main ducts and the second and fourth main ducts being suitable for being connected in respective pairs to respective orifices of a pump for feeding and discharging the motor sets in parallel; said hydraulic circuit further comprising a selector device according to claim 1 for selecting the overall cubic capacity of the circuit. 19. A hydraulic circuit according to claim 18, further comprising an exchange device having an exchange selector which has two inlet ports connected to respective ones of the first and fourth main ducts, and an outlet port to which that one of said inlet ports that is at the lower pressure is suitable for being connected.