FR2674580A1 - Device for controlling a hydraulic boost motor - Google Patents

Abstract

Device for controlling a hydraulic boost motor providing secondary circulation of hydraulic fluid in the said hydraulic motor (1) in order to lubricate it when the distributor device (2) calls for the boosting to be cut off. This device includes a valve (10) mounted in parallel with the said motor (1) between pipes (14, 15) connected to the primary feed circuit on either side of the said motor, and which is driven hydraulically via its existing pipes arriving at the said motor, without it being necessary to add a special pipeline, in order to pass from a position I for which it establishes the communication between the pipes (14, 15) located on either side of the motor to a position II for which it cuts off this communication.

Description

Control device for a hydraulic assistance motor
The present invention relates generally to so-called all-terrain vehicles such as agricultural tractors or other harvesting machines. In these vehicles, the main traction is provided by the rear wheels driven by mechanical devices while hydraulic assistance is generally provided on the front wheels which do not provide the main traction.

 This hydraulic assistance is usually provided by hydraulic devices comprising hydraulic motors mounted on said wheels.

 The present invention then relates more precisely to the control of these hydraulic assistance motors.

 Hydraulic devices are only used to provide partial traction when the machine is in the process of working, that is to say advancing at a fairly low speed. They usually consist of a variable flow pump and hydraulic motors placed very close to the wheels, often in their hub.

 Lines ensure the supply of said motors with hydraulic fluid.

 A distribution device is also provided in said hydraulic devices, interposed between the pump and the motors in order to supply the latter in forward or reverse direction depending on the movement which the machine must make.

 This distribution device cuts off the power to the motors during movement of the machine for which assistance is not necessary, that is to say when going downhill or on the road. In these cases, the wheels of the machine rotate driving the hydraulic motors which are linked to them and causing them to operate at the pump stop while the supply of hydraulic fluid is cut off which causes deterioration of said motors if their design is not suitable.

 Therefore, the hydraulic motors adapted to be used in these devices are motors which can be considerably reduced and even canceled the displacement so that the cancellation of the circulation of hydraulic fluid from the distribution device when none assistance is not necessary does not cause harmful effects.

 These engines whose displacement can be canceled are generally very expensive which pushes many manufacturers to prefer to use other types of engines.

 The use of disengageable motors has also been proposed, but these are still too expensive.

 The use of more conventional hydraulic motors arranged in the wheels of the machine however requires providing a secondary circulation of hydraulic fluid in the motor in order to ensure its lubrication when the distribution device cuts the primary supply to the motor.

 To ensure this secondary circulation, there is sometimes an electro-distributor in the control circuit of each motor which controls a short loop circulation between the inlet and the outlet of the engine so that it is always crossed by hydraulic fluid and thus avoid the risk of seizure. The control circuits using such solenoid valves are not entirely satisfactory since these solenoid valves are bulky and quite fragile, and it is necessary to control them by an electric line which is also fragile in the environment considered.

 It has also been proposed to have pilot-operated check valves but it is then necessary to have additional hydraulic pipes as well as a pressurizing device which makes this proposal also unattractive.

 The present invention therefore tends to propose a new device for controlling these hydraulic assistance motors which is both inexpensive and not very fragile.

 The invention relates to a device for controlling a hydraulic assistance motor, of the type enabling secondary circulation of hydraulic fluid in said hydraulic motor to ensure its free lubrication and rotation when the distribution device that it does not ensure the primary supply of said hydraulic motor by a circulation of the hydraulic fluid between a pump and a tank, so that it does not provide assistance, characterized in that a valve is mounted in parallel with said motor between conduits connected to the primary supply circuit on either side of said motor, said valve being controlled hydraulically via existing conduits arriving at said motor, without the need to add a special pipe, in order to pass from a position I for which it establishes communication between the conduits situated on either side of the engine to a position II for which el cut off this communication.

 In a first embodiment, the control device according to the invention is characterized in that said valve is at rest in position II for cutting off the communication between the conduits located on either side of the motor and is controlled by the pressure prevailing in the drainage circuit of the internal leaks of said motor, which drainage circuit is placed in communication with the outlet of the pump (and therefore under pressure) by means of a solenoid valve which is actuated when the distribution device cuts the power supply to the motors and includes a calibrated valve limiting the pressure in the circuit to a value slightly higher than the control pressure of said valve.

According to this embodiment
- when no assistance is required, the distribution device is in position 0 and cuts the communication between the pump and the primary supply circuit, while the solenoid valve located on the drainage circuit is in position I putting the circuit drainage at the pressure regulated by the calibrated valve,
- when assistance is required, the distribution device is placed in a position I or II ensuring the primary supply of said hydraulic motor by a circulation of the hydraulic fluid between a pump and a tank, while the solenoid valve is controlled to pass in position II connecting the drainage circuit to the cover.

In a second embodiment, the control device according to the invention is characterized in that
said piloted valve is in the rest position in position I for which the communication between the conduits located on either side of the motor is open and is controlled by the pressure supplied to the circuit by the pump through the distribution device, via a circuit selector,
the distribution device is such that in position 0 it puts the conduits of the primary supply circuit of the engine into communication with the conduits connected to the pump and to the cover,
- a valve calibrated at a pressure higher than the valve control pressure and a solenoid valve are arranged in parallel on the conduit between the distribution device and the tank,
- the solenoid valve has a position I ensuring circulation towards the tank through a calibrated valve with setting pressure lower than the valve control pressure or passing through a point of the circuit in light pressure and a position II cutting this communication,
- the engine drainage duct and the outlets of the calibrated valves are connected to the tarpaulin.

According to this embodiment
- when no assistance is required, the distribution device is in position 0 and the solenoid valve in position I,
- when hydraulic assistance is required, the distribution device is in one of positions I or II and the solenoid valve is in position II.

The device according to the invention is further characterized in that
said valve comprises a movable plug in a body being subjected to the action on the one hand of a spring and on the other hand of a control pressure,
the conduits located on either side of the engine open into the internal chamber of the body in which the plug is disposed,
- said plug has a groove to allow the communication of said conduits,
- A vent is arranged on the side of the plug where the spring is arranged.

The present invention will be better understood as well as other characteristics and advantages thereof by the description which follows with reference to the drawing in which
FIG. 1 is a first alternative embodiment of a device according to the invention,
FIG. 2 represents the valve piloted in the closed position of the secondary circuit,
FIG. 3 represents the valve piloted in the open position of the secondary circuit,
FIG. 4 is a second alternative embodiment of a device according to the invention,
FIG. 5 represents the valve piloted in the closed position of the secondary circuit,
FIG. 6 represents the valve piloted in the open position of the secondary circuit,
- Figure 7 is a third alternative embodiment of a device according to the invention.

 In FIG. 1, we can first of all see the usual control circuit for hydraulic motors 1a and 1b each arranged in a wheel in order to provide temporary partial assistance to the machine thus equipped.

 These motors are supplied with hydraulic fluid from the pump P sending pressurized liquid into the circuit through a three-position control solenoid valve 2.

 Position O is the position of said solenoid valve 2 when no assistance is required.

 The assistance of the hydraulic motors is provided when the solenoid valve 2 is in one of the positions I or II, one of these positions corresponds to the forward gear while the other corresponds to the reverse gear.

 If we consider the position I of the solenoid valve 2, the hydraulic fluid circulates in the primary supply circuit leaving this solenoid valve by the conduit 4 which is divided into two branches 4a and 4b for supplying the motors la and lb arranged in parallel.

The motors exit via the conduits 5a, 5b which join in a single conduit 5 for the return to the cover B by the conduit 40.

 In a manner known per se, the oil leaks appearing during the operation of the engines are discharged through the drainage conduits 7a and 7b ensuring the circulation of the oil towards the tank B.

 In the first embodiment of the control device according to the invention shown in FIG. 1, there is arranged in parallel with each motor 1a, 1 a piloted valve 10a, 10b whose piloting is done by the pressure prevailing in conduits 8a, 8b connected to the drainage conduits 7a, 7b and interposed between said drainage conduits, the pump P and the tank B on the one hand a solenoid valve 6 and on the other hand a calibrated valve 9.

 In this exemplary embodiment, the communication between the pump and the primary supply circuit of the motors is cut off when the solenoid valve 2 is in position 0 while the conduits 4 and 5 of the primary supply circuit are in communication with the tank. B through conduit 40.

 Valves lova, 10b are two-position valves which, in position I establish communication between conduits 14a, 14b and conduits 15a, 15b connected to the primary supply circuit on either side of the motors, and, in position II cut off this communication.

 Such a valve 10 is represented in FIGS. 2 and 3. This valve comprises a plug 12 movable in a body 11 while being subjected to the action on the one hand of a spring 13 and on the other hand of the pressure X of the pipeline 8.

 The conduits 14, 15 open into the internal chamber of the body 11 in which the plug 12 is arranged, and the latter has a groove 12a in order to allow the communication of said conduits. The conduits 14, 15 open into circumferential grooves provided in the internal surface of the body 11 in order to ensure a better distribution of the pressures on the plug 12.

 A vent 16 is also provided on the side of the plug 12 where the spring 13 is arranged in order to ensure the escape of the air contained in the internal chamber and to allow the movement of said plug in good conditions.

 The solenoid valve 6 is disposed between on the one hand a conduit 70 connected to the drainage conduits 7a, 7b and on the other hand a conduit 74 connected to the outlet of the pump P through a restriction 75 and a conduit 73 connected to the tarpaulin B.

 As shown diagrammatically in FIG. 1, it is a two-position valve which, in position I puts the drainage conduits 7a, 7b, 70 into communication with the conduit 74 connected to the pump, and, in position II puts the said drainage conduits 7a, 7b, 70 in communication with the cover B by the conduit 73.

 The calibrated valve 9 is interposed between a conduit 71 connected to the drainage conduits 7a, 7b and a conduit 72 leading to the cover B.

 When the control valve 2 is brought by the excitation of one of the coils 20 to one of the positions I or II for which the motors 1a, 1b are activated in order to provide the necessary assistance, the solenoid valve 6 is brought by the excitation of its coil 60 in position II for which the oil from the leaks is sent to the tank B. The pressure X applied to the plug 12 is then zero and the latter is in the position shown in FIG. 2 in which it is pushed by the spring 13 and cuts the communication between the conduits 14, 15. The device then has the same operation as the known devices.

On the other hand, when no assistance is needed, the coils 20 and 60 are not energized, the control solenoid valve 2 is in position 0 for which the motors are not activated to provide assistance, while the solenoid valve 6 is in position
I.

 The pressure supplied by the pump P then prevails in the drainage conduits, being modulated by the calibrated valve 9 so as to be limited to a value slightly greater than the control pressure of the valves 10a, 10b.

The pressure X thus applied to the rear of the plug 12 of each valve 10a, 10b exerts on it a force greater than that exerted by the spring 13 and moves said plug to the position shown in FIG. 3.

Said valves 10a and 10b are brought into their position
I for which the conduits 14a, 14b and 15a, 15b located on either side of the motors 1a and 1b are placed in communication respectively by the groove 12a of the plug 12.

 In this arrangement of the valves, a hydraulic fluid circulation occurs between the conduits situated at the inlet and at the outlet of the motors in order to allow their operation as a pump when they are driven by the wheels on which they are mounted.

 The light pressure then prevailing in the drainage circuit will allow a weak circulation due to internal leaks to be established between the drainage circuit 70, 7a, 7b and the conduits 4, 5, 40 connected to the cover B. Such circulation ensures the lubrication of the motors 1a, 1b as well as the renewal of the hydraulic fluid.

 As soon as the solenoid valve 2 is controlled to move to one of its positions I or II to provide hydraulic assistance, the solenoid valve 6 is controlled to move to position II. The drainage circuit is then again connected to the tank B and the pressure prevailing in the conduits 8a, 8b is canceled. The valves 12 of the valves 10a, 10b are then subjected to the sole action of the springs 13 and brought back to the position of FIG. 2 for which they cut the communication between the respective conduits 14, 15, the valves 10a, 10b are again in their position there.

 In the alternative embodiment of FIGS. 4 to 6, the piloted valves 110a, 110b arranged in parallel with the motors are valves in which the plug 112 is held by the spring 113 in the position for which it opens the communication between the conduits 14 and 15, the closing of this communication being ensured by the pressure supplied to the circuit by the pump P through the control solenoid valve 102.

 At its end opposite to that subjected to the action of the spring 113, the plug 112 is subjected to a pressure Y defined by a circuit selector 130.

 This circuit selector comprises a housing 131 connected to the conduits 14, 15 arranged on either side of the motor 1, said housing 131 also communicates by a conduit 132 with the internal chamber of the valve 110 in which the plug 112 is disposed on the side. of it not subject to the action of the spring 113.

 The circuit selector 130 also includes a ball 134 intended to close one or the other of the orifices through which the conduits 14, 15 are in connection with the housing 131.

 By such an arrangement, when the solenoid valve 102 is in one of its positions I or II for which the motors 1a, 1b are supplied in order to provide hydraulic assistance, the ball 134 subjected to the pressure of the pump P arriving respectively in the housing 131 of the selector 130 by the conduit 14 or by the conduit 15 will be positioned so as to close off the other conduit 15 or 14.

 FIG. 5 represents the position II taken by the solenoid valve 102 when the pressure Y coming from the pump P is applied to the plug 112 and pushes the latter against the spring 113 in order to cut off the communication between conduits 14 and 15.

 In this variant embodiment of the invention, position 0 of the solenoid valve 102 puts the conduits 4 and 5 of the primary supply circuit of the motors in communication with the conduits 50 connected to the pump P and 51 connected to the cover B .

 Two calibrated valves 109, 140 are arranged in parallel on the conduit 51 between the solenoid valve 102 and the tank B, one of which, the valve 140 at low setting pressure is linked to a solenoid valve 106.

 The solenoid valve 106 comprises a position I putting the conduit 51 in communication with the tank B through the calibrated valve 140 and a position II cutting off this communication.

 The setting pressure of the valve 140 is lower than the control pressure of the valves 110 while the setting pressure of the valve 109 is greater than said control pressure of the valves 110.

 The drainage conduit 7 into which the drainage conduits 7a, 7b of the motors open is connected to the conduit 52 connecting the outputs of the calibrated valves 109 and 140 to the cover B.

 When the hydraulic assistance is no longer necessary, the coils 120, 160 of the solenoid valves 102 and 106 are no longer energized and said solenoid valves take positions 0 and I respectively.

 The pump P then sends the hydraulic fluid into the conduits 50, 4, 5, 51. The pressure prevailing in the circuit is controlled by the tared valves 109, 140. The valve 140 being tared at a low value, it is therefore this pressure in the circuit.

 Therefore, the pressure Y exerted on the valve 112 is lower than the control pressure of the valve 110 and said valve is pushed back by the spring 113 in its position shown in FIG. 6 for connecting the conduits 14, 15 The valve 110 is thus in its position I for which it establishes a circulation between said conduits 14, 15.

 A circulation can then be established by these conduits 14 and 15 in order to allow the motors to operate without damage in pumps when they are driven by the wheels of the machine. The leakage drainage circuit will allow a passage of hydraulic fluid in the direction of the tank to ensure the lubrication of the engines as well as the renewal of the oil.

 When assistance becomes necessary, one of the coils 120 is energized as well as the coil 160 in order to bring the solenoid valve 102 to one of positions I or II and the solenoid valve in position II isolating the calibrated valve 140 .

 The pressure prevailing in the circuit is then that of the calibration of the valve 109, this pressure being greater than the control pressure of the valves 110, said valves assume their position II for cutting off the communication between the respective conduits 14a, 14b and 15a, 15b .

 Of course, the calibrated valve 140 with very low calibration pressure can in practice be eliminated by connecting the outlet of the solenoid valve 106 to a point of the circuit in light against pressure.

 FIG. 7 represents a variant of the device according to the invention, the operation of which is identical to that of the embodiment of FIG. 4.

 This figure shows devices 3a, 3b comprising two non-return valves making it possible to drain the leaks and return them to the return duct of the motors 1a, 1b. Such devices are known and arranged in the motor casing, which eliminates the need to provide a drainage conduit bringing these leaks back to the tank.

 As will have been understood, the provisions of the invention allow the use of widely available and inexpensive hydraulic motors to provide assistance on all-terrain vehicles by ensuring lubrication circulation thereof when a assistance is not necessary without the need for an expensive device, nor for control links which may be fragile.

 In fact, the valves 10, 110 arranged against the motors 1a, 1b are valves requiring no electrical control wire and it is possible to create a compact assembly represented by the traces A including the motors and said valves. In this way, it is not necessary to add pipes to existing devices.

Claims (6)

 1. Control device for at least one hydraulic assistance motor, of the type allowing secondary circulation of hydraulic fluid in said hydraulic motor (1) to ensure its free lubrication and its rotation when the distribution device (2, 102) that it comprises does not ensure the primary supply of said hydraulic motor by a circulation of the hydraulic fluid between a pump (P) and a tank (B), so that it does not provide assistance, characterized in that a valve (10, 110) is mounted in parallel with said motor (1) between conduits (14, 15) connected to the primary supply circuit on either side of said motor, said valve (10, 110) being hydraulically controlled by means of the existing pipes arriving at said motor (1), without the need to add a special pipe, in order to pass from a position I for which it establishes communication between the pipes ( 14, 15) located on either side other side of the engine at a position II for which it cuts off this communication.  2. Control device according to claim 1, characterized in that said valve (10) is at rest in position II for cutting off the communication between the conduits (14, 15) located on either side of the motor and is controlled by the pressure prevailing in the drainage circuit of the internal leaks of said motor, which drainage circuit is placed in communication with the outlet of the pump (and therefore under pressure) by means of a solenoid valve (6) which is actuated when the device distribution cut off the power supply to the motors and includes a calibrated valve (9) limiting the pressure in the circuit to a value slightly higher than the control pressure of said valve (10)  3. Control device according to claim 2, characterized in that  - when no assistance is required, the distribution device (2) is in position 0 and cuts the communication between the pump (P) and the primary supply circuit, while the solenoid valve (6) located on the circuit of drainage is in position I putting the drainage circuit at the pressure regulated by the calibrated valve (9),  - when assistance is required, the distribution device (2) is arranged in a position I or II ensuring the primary supply of said hydraulic motor by a circulation of the hydraulic fluid between a pump (P) and a tank (B), while the solenoid valve  (6) is controlled to move to position II connecting the drainage circuit to the cover.  4. Control device according to claim 1, characterized in that  - Said piloted valve (110) is in the rest position in position I for which the communication between the conduits (14, 15) located on either side of the motor is open and is controlled by the pressure supplied to the circuit by the pump (P) through the distribution device (102), via a circuit selector (130),  - the distribution device is such that in position 0 it connects the conduits (4, 5) of the primary supply circuit of the engine with the conduits (50, 51) connected to the pump (P) and to the tank (B),  - a valve (109) calibrated at a pressure higher than the control pressure of the valve (110) and a solenoid valve (106) are arranged in parallel on the conduit (51) between the distribution device (102) and the tank ( B),  - the solenoid valve (106) has a position I ensuring circulation towards the tank (B) through a calibrated valve (140) at a setting pressure lower than the control pressure of the valve (110) or passing through a point of circuit slightly against pressure and one position He's cutting off that communication,  - the engine drain pipe (7) and the outlets of the calibrated valves (109, 140) are connected to the cover (B).  5. Control device according to claim 4, characterized in that  - when no assistance is required, the distribution device (102) is in position 0 and the solenoid valve (106) in position I,  - When hydraulic assistance is required, the distribution device (102) is in one of the positions I or II and the solenoid valve (106) is in the position II.  6. Control device according to any one of the preceding claims, characterized in that  - Said valve (10, 110) comprises a plug (12, 112) movable in a body (11, 11) being subjected to the action on the one hand of a spring (13, 113) and on the other hand a control pressure,  the conduits (14, 15) located on either side of the motor (1) open into the internal chamber of the body tll, 111) in which the plug (12, 112) is arranged,  said plug (12, 112) has a groove (12a, 112a) in order to allow said conduits (14, 15) to be placed in communication,  - A vent (16, 116) is disposed on the side of the plug (12, 112) where the spring (13, 113) is arranged.