FR3087714A1 - HYDROSTATIC TRANSMISSION FOR A MOBILE MACHINE MOVING ON SLOPING AND SLOPING GROUND - Google Patents

Abstract

The invention relates to a hydrostatic transmission for a mobile machine moving on sloping and sloping terrain comprising a hydraulic pump (10), a first axle equipped with left (20) and right (30) hydraulic motors, a second axle equipped a double left (40) and right (60) hydraulic motor, hydraulic connections (100, 110, 120, 130) a) between a port of the pump (10) and a port of the motors (20, 30) of the first axle and a first elementary motor (46, 66) of the motors (40, 60) of the second axle, b) between a second port of the pump (10) and a second port of the two elementary motors (44, 46, 64, 66) of the two motors (40, 60) of the second axle and c) in series between the motors (20, 30) of the first axle and a second elementary motor (44, 64) of the motors (40, 60) of the second axle, characterized by the fact that it comprises restrictions (210, 220) switchable between an inactive state and an active state on the link connecting the hydraulic pump (10) respectively to the second port of the two motors (40, 60) of the second axle and means (UC) adapted to activate one of the restrictions when the machine moves on sloping ground.

Description

The present invention relates to the field of hydrostatic transmission devices for mobile vehicles.

Many hydrostatic transmission systems for mobile vehicles have already been proposed.

In particular, systems of the type illustrated in the appended FIG. 1 are known.

These systems include a hydraulic pump 10 driven by a motor 12, for example a heat engine of the machine, a left front hydraulic motor 20 coupled to a left front wheel 22, a right front hydraulic motor 30 coupled to a right front wheel 32 , a double left rear hydraulic motor 40 coupled to a left rear wheel 42 and a double right rear hydraulic motor 60 coupled to a right rear wheel 62.

The double motors 40 and 60 each consist of a first elementary motor 44, 64 and a second elementary motor 46, 66 mechanically coupled, each of the two elementary motors 44, 46 and 64, 66 having supply ports. distinct.

As a variant, the pump 10 can be powered by a motor 12 of the electric type.

A hydraulic link 100 connects a first port of the pump 10 with a first port of the front motors 20, 30 and with a first port of the first rear elementary motors 46, 66.

A second hydraulic link 110 connects the second port of the pump 10 and a second port common to the two elementary motors 44, 46, 64, 66 of the rear motors 40, 60.

Finally, a serial link 120, 130 respectively connects the second port of the front motors 20, 30 and a first port of the second elementary motors 44, 64 of the rear motors 40, 60.

The structure shown in the attached FIG. 1 previously described corresponds to a structure called “Twinlock” in the terminology of specialists.

It is offered in particular by the company POCLAIN HYDRAULICS.

2 Such a hydrostatic transmission structure is described for example in document EP 0 547 947.

Variants of this hydrostatic transmission are described in document FR 2 913 218.

The structure of the circuit thus proposed which places in series the displacements of the front motors 20, 30 and respectively the second elementary motors 44, 64 of the rear motors 40, 60, makes it possible to ensure synchronization of the front and rear driving wheels of the machine. and an automatic and instantaneous torque transfer to the 10 wheel (s) which have better grip.

Each wheel is thus synchronized with the forward speed of the machine.

The present invention is aimed in particular at devices intended to move on steep slopes and on slopes.

In the context of the invention, the term “slope” is understood to mean the inclination with respect to the horizontal of the ground taken in a direction which coincides with the longitudinal axis of the machine, and the term “cant” is understood to mean the inclination. relative to the horizontal of the ground taken in a direction transverse to the longitudinal axis of the machine.

It has been observed that when a machine equipped with a hydrostatic transmission of the type illustrated in FIG. 1 moves on a slope and on a steep slope, it may be subject to a downward sliding of the slope.

More precisely, when a machine equipped with a “twinlock” circuit as illustrated in FIG. 1 works on a slope, the machine tends to deviate from its trajectory.

The rear axle equipped with 40, 60 double motors tends to drift in the direction of the slope.

The driver is then obliged to correct the trajectory, but it is however difficult to achieve this.

An attempt at a known solution already proposed consists in trying to reduce the braking torque on the front wheel located on the upper lateral side compared to the braking torque on the rear wheel on the slope side, by reducing the pressure in the series pipe located on the 3 on the upper side, for example using a valve fitted with a restriction placed on each series 120, 130 pipe.

This solution, which requires equipping each 120, 130 series line, is however complex and is not completely satisfactory.

5 To help limit drift to slope, adding a flow divider to the return of the rear engines tends to help improve the situation.

However, this solution does not completely resolve slippage on a slope.

Moreover, this correction is only valid over a speed range due to the presence of the flow divider.

In this context, the object of the present invention is now to improve the state of the art and to improve the maintenance on the trajectory of a machine moving on a steep slope and on a slope.

The aim of the invention is in particular to provide means which make it possible to independently manage the holding torque on each side of the vehicle and therefore to maintain the trajectory of the vehicle when it is moving on a sloping slope.

This object is achieved according to the invention thanks to a device for hydrostatic transmission of a mobile machine, of the type comprising a hydraulic pump, a first axle equipped with a left hydraulic motor and a right hydraulic motor, a second axle equipped with a double left hydraulic motor and a double right hydraulic motor, a hydraulic link providing a connection between a first port of the pump and a first port of the motors of the first axle and of a first elementary motor of the motors of the second axle, a hydraulic link providing a link between a second port of the pump and a second port of the two elementary motors of the two motors of the second axle and serial links respectively between a second port of the motors of the first axle and a first port of the 30 second elementary motors of the motors of the second axle, characterized by the fact that it comprises switchable restrictions between an inactive state and an active state on the link connecting the hydraulic pump respectively to the second port of the two motors of the second axle and 4 means adapted to activate one of the restrictions when the machine moves on sloping ground.

The restrictions can be switchable in steps between at least two positions corresponding to an inactive rest position of full passage and a working position of reduced section.

According to one variant, the restrictions may have a section that varies progressively on order.

Preferably, the restrictions are placed on the link ensuring the return to the pump.

More precisely still, preferably, the restrictions are placed on the connection between the pump and the twin motors disposed on the rear axle.

According to the invention, there is thus preferably provided at least one respective restriction between the pump and the double motor located respectively on each side of the vehicle, typically on the return link of the respective rear motors, or a restriction on the hydraulic link to left and a restriction on the hydraulic link on the right.

As a variant, provision may be made for a respective restriction between the pump and at least one elementary motor, that is to say a restriction on the hydraulic connection on the left connected to one of the two elementary motors located on the left and a restriction on the hydraulic connection on the right. connected to one of the two elementary motors located on the right, or a respective restriction may be provided between the pump and each elementary motor, i.e. two restrictions on the hydraulic connection on the left connected respectively to the two elementary motors located on the left and two restrictions on the hydraulic link on the right connected respectively to the two elementary motors located on the right.

The present invention also relates to a method of hydrostatic transmission of mobile vehicles using a device of the aforementioned type, characterized in that it consists in controlling restrictions placed on a link connecting the hydraulic pump respectively to the hydraulic pumps. two motors of the second axle, when the machine 5 is moving on sloping ground, to activate the restriction located on the link on the cant side connecting the hydraulic pump to the two motors of the second axle.

The present invention also relates to vehicles equipped with a hydrostatic transmission device of the aforementioned type and / or implementing the aforementioned method.

Other characteristics, aims and advantages of the present invention will become apparent on reading the detailed description which follows, and with regard to the appended drawings, given by way of non-limiting examples and in which: FIG. 1 previously described represents a hydrostatic transmission system for mobile vehicles in accordance with the state of the art, FIG. 2 diagrammatically represents a hydrostatic transmission system for mobile vehicles according to the invention, FIG. 3 illustrates an example of the pressures reigning within the hydraulic connections of a transmission device according to the invention moving on sloping and sloping terrain, without implementation of the restrictions according to the invention, FIG. 4 illustrates an example of the correction of the pressures prevailing within the hydraulic connections of a transmission device according to the invention moving on sloping and sloping ground, thanks to the restrictions con forms according to the invention, and FIG. 5 diagrammatically represents an alternative embodiment of a hydrostatic transmission in accordance with the present invention.

FIG. 2 shows a hydrostatic transmission device of the type illustrated in FIG. 1 supplemented by a piloted valve 200 comprising restrictions 212, 222 which can be selectively switchable on command when the machine is moving on sloping and sloping terrain.

It will be recalled that as described above with regard to FIG. 1, the system illustrated in FIG. 2 comprises a hydraulic pump 10 driven by a motor 12 such as a heat engine or electric motor 6, on a first axle, for example a front axle , a left hydraulic motor 20 associated with a left wheel 22 and a right hydraulic motor 30 associated with a right wheel 32, and on a second axle, for example a rear axle, a double left hydraulic motor 40 comprising two elementary motors 44, 46, associated with a left wheel 42 and a double right hydraulic motor 60 comprising two elementary motors 64, 66 coupled to a right wheel 62.

As a variant, the wheels 22, 32, 42 and 62 may be replaced by any equivalent means suitable for effecting a movement on the ground, for example toothed gears suitable for driving caterpillars.

A link 100 connects a first port of the hydraulic pump 10 to a first port of the front motors 20, 30 and to a first port 15 of the first elementary motors 46, 66.

A second link 110 provides a link between the second port of the pump 10 and a port common to the elementary motors 44, 46, 64, 66, of the rear motors 40, 60 (this common port being called the second port of the elementary motors).

Finally, a serial link 120, 130 respectively connects the second port of the front motors 20, 30 and the first port of the second elementary motors 44, 64 of the rear motors 40, 60.

The restrictions 212, 222 are placed respectively on the sections 110g and 110d of the link 110 connecting the hydraulic pump 10 25 respectively to the second port of the two motors 40, 60 of the second axle.

They are switchable on command between an inactive state in which the restrictions 212 and 222 allow full passage of the fluid on the connections 110g and 110d, and an active state in which the restrictions 212 and 222 have a reduced section limiting the passage of the fluid on the respective bonds 110g and 110d.

The system also includes means adapted to selectively activate one of the restrictions 212, 222, namely the restriction 212, 222 located on the side of the slope, when the machine is moving over sloping terrain.

The restrictions 212, 222 can be switchable in steps between at least two positions corresponding to an inactive rest position 5 full passage and a working position of reduced section, or even several possible intermediate steps selected by an appropriate control in particular as a function of the Importance of the slope, between the inactive position of full passage and a position of minimum section.

According to one variant, the restrictions 212, 222 may have a section that is progressively variable on order.

The restrictions 212, 222 can be the subject of many embodiments as to their construction.

As shown diagrammatically in FIG. 2, the restrictions 212, 15 222 can be integrated into a controlled valve 200 constituted by at least two distributors 210, 220 respectively arranged on a connecting section 110g between the point common to the two left rear elementary motors. 44, 46 and the second port of the pump 10 and on a connecting section 110d between the point common to the two right rear elementary motors 64, 66 and the second port of the pump 10.

Each restriction can thus be achieved by a distributor comprising a slide which moves between at least two positions corresponding to the inactive state and to the active state of the restrictions.

The distributors 210, 220 are switchable between two states.

In a first state, the distributors 210, 220 provide a direct connection between the common point of the elementary motors 44, 46 and 64, 66 and the second port of the pump 10, without restriction as to the passage of fluid.

In the second state or second position, the 30 distributors 210, 220 form a restriction 212, 222 of controlled section on the aforementioned connections 110g or 110d located respectively between the common point of the left rear elementary motors 44,46 and the second port of the pump 10 and between the common point of the 8 rear right elementary motors 64, 66 and the second port of pump 10.

As indicated previously, the restrictions 212, 222 incorporated in the distributors 210, 220 can be switchable between two all or nothing states or several steps of predefined sections or even progressively between an inactive state of maximum section and a state of minimum section.

By positioning a controlled section restriction on the aforementioned connections 110g or 110d, the invention makes it possible to brake the rear motor located in the slope and to brake the corresponding front motor via the series line 120 or 130 to brake the machine on the entire side. in the slope and thus modify the trajectory of the vehicle to put the vehicle back on a correct trajectory.

As can be seen in FIG. 2, the valve 200 may furthermore comprise distributors 215, 225 controlling the distributors 210, 220 on the basis of any appropriate signal indicative of a tilting movement and, where appropriate, of a start. slip.

All of the distributors 210, 220 defining a variable section restriction and the piloting distributors 215, 225 are advantageously grouped together in a common box.

This set of pilot distributors 215, 225 and distributor 210, 220 is advantageously integrated into a compact valve unit.

The aforementioned means can be the subject of numerous variant embodiments.

The distributors 210 and 220 can be controlled directly hydraulically, pneumatically or electrically, or by a relay stage, for example as shown in FIG. 2, by an electric stage which controls a pressure regulating valve (here the distributors 215, 225) which itself hydraulically controls the distributors 210, 220.

Preferably, the system according to the invention thus further comprises at least one of the following components intended to control the valve 200: at least one sensor which measures the pressure at the terminals of the double motors 44, 46, 64, 66 , an inclinometer, a speed sensor 9 of the front wheels, a proximity sensor or a shooting system, radar or even an inertial unit.

For example, the inclinometer makes it possible to discriminate the fact that the machine is on an incline and the pressure sensors make it possible to discriminate the rise in pressure 5 at the terminals of the elementary motors beyond a certain threshold or to detect a difference in difference of pressure between the right and left elementary motors beyond a certain threshold.

A row or proximity sensor (mechanical, optical, or other) makes it possible to detect the slippage of the machine and to control the valve accordingly.

10 The use of an inertial unit also makes it possible to detect the sliding of the rear of the vehicle and to trigger the piloting of the valve. As a variant or in addition, the restrictions 212, 222 can be piloted manually by the pilot of the machine , when the latter tends to slide in the cant.

The control applied to the restrictions 212, 222, whether manual or automatic, may be an all or nothing control, or a control proportional to the slope.

In the context of the invention, the control of the restrictions 212, 222 can also be mixed, manual and automatic.

It is thus possible to provide for a manual activation command on the initiative of the pilot of the vehicle accompanied by fine adjustment on the basis of information from relevant sensors.

It is also possible to provide for a basic automatic control based on information from relevant sensors 25, refined by manual correction if this appears necessary.

In FIGS. 2 and 5, the means suitable for activating one of the restrictions 212 or 222 when the machine moves on sloping terrain are shown diagrammatically in the form of a central unit referenced UC.

FIG. 3 shows an example of the pressures prevailing within the hydraulic connections 100, 110, 120 and 130 of a transmission device according to the invention moving on sloping and sloping terrain, without implementing the restrictions 212, 222 in accordance with the invention.

FIG. 4 shows a simulation of the correction of the pressures prevailing within these hydraulic connections 100, 110, 5 120 and 130 of a transmission device according to the invention moving on sloping ground and on a slope, thanks to the activation of the restriction 212 or 222 according to the invention located on the lower lateral side of the slope.

Arbitrarily, the simulations illustrated in FIGS. 3 and 4 correspond to a slope "PE" descending towards the front and a cant "DE" descending towards the left.

In this case, the vehicle equipped with the hydrostatic transmission tends to slide down the slope, more precisely the left rear wheel 42 tends to slide down the slope.

The activation of the restriction 212 located on the low side of the slope, however, makes it possible to increase the pressure at the terminals of the corresponding rear double motor 40 and consequently to increase very appreciably the braking torque on this motor.

FIG. 5 shows an alternative embodiment 20 in accordance with the present invention according to which there is provided a respective controlled variable restriction 212.1, 212.2, 222.1 and 222.2 between the second port of the pump 10 and the second port of each elementary motor. 44, 46, 64, 66.

According to Figure 5 there are thus provided two controlled variable restrictions 212.1, 212.2 on the hydraulic connections 25 on the left 110g1 and 110g2 respectively connected to the two elementary motors 44, 46 located on the left and two controlled variable restrictions 222.1 and 222.2 on the hydraulic connections to right 110d1 and 110d2 respectively connected to the two elementary motors 64, 66 located on the right.

The fact of having restrictions 212.1, 212.2, 222.1 and 222.2 associated respectively with each elementary motor 44, 46, 64, 66 makes it possible to refine the pressure correction adapted to the cant.

This arrangement in fact makes it possible to multiply the number of possible combinations with regard to the applicable restriction sections.

According to another variant embodiment, it is possible to provide a restriction only 212.1 or 212.2, respectively 222.1 or 222.2 on the left and on the right, associated with one of the elementary motors 44, 46 on the left, respectively with one of the elementary motors. 64, 66 rights.

Of course, the present invention is not limited to the particular embodiments which have just been described but extends to any variant in accordance with its spirit.

The invention applies to the drive of any machine equipped with a hydrostatic transmission capable of being moved on a sloping slope,

Claims (14)

CLAIMS 1. Device for hydrostatic transmission of a mobile machine, of the type comprising a hydraulic pump (10), a first axle fitted with a left hydraulic motor (20) and a right hydraulic motor (30), a second axle fitted with a double left hydraulic motor (40) and a double right hydraulic motor (60), a hydraulic link (100) providing a link between a first port of the pump (10) and a first port of the motors (20, 30) of the first axle and of a first elementary motor (46, 66) of the motors (40, 60) of the second axle, a hydraulic link (110) providing a link between a second port of the pump (10) and a second port of the two elementary motors (44, 46, 64, 66) of the two motors (40, 60) of the second axle and serial links (120, 130) respectively between a second port of the motors (20, 30) of the first axle and a first port of the second elementary motors (44, 64) of the motors (40, 60) of the second axle, characterized in that it comprises restrictions (212, 222) switchable between an inactive state and an active state on the link connecting the hydraulic pump (10) respectively to the second port of the two motors (40, 60) of the second axle and means (UC) adapted for activate one of the restrictions when the machine is moving over sloping terrain. 2. Device according to claim 1, characterized in that the restrictions (212, 222) are switchable in steps between at least two positions corresponding to an inactive rest position of full passage and a working position of reduced section. 3. Device according to claim 1, characterized in that the restrictions (212, 222) are of variable section progressively on command. 4. Device according to one of claims 1 to 3, characterized in that the restrictions (212, 222) are placed on the connection (110) ensuring the return to the pump (10). 5. Device according to one of claims 1 to 4, characterized in that the restrictions (212, 222) are placed on the connection (110, 13 110g, 110d) between the pump (10) and the double motors (40 , 60) arranged on the rear axle. 6. Device according to one of claims 1 to 5, characterized in that a respective restriction (212, 222) is provided between the pump (10) and the double motor (40, 60) located respectively on each side. of the vehicle, typically on the return link (110, 110g, 110d) of the respective rear motors, i.e. a restriction (212) on the hydraulic link on the left (110g) and a restriction (222) on the hydraulic link on the right (110d) . 10 7. Device according to one of claims 1 to 5, characterized in that a restriction (212.1, 212.2, 222.1, 222.2) is provided between the pump (10) and at least one elementary motor (44, 46, 64 , 66), or at least one restriction on the hydraulic connection on the left connected to one of the two elementary motors located on the left (44, 46) and at least one restriction on the hydraulic connection on the right connected to one of the two elementary motors located on the right (64, 66). 8. Device according to one of claims 1 to 5 and 6, characterized in that a respective restriction (212.1, 212.2, 222.1, 222.2) is provided between the pump (10) and each elementary motor (44, 46, 64, 20 66), i.e. two variable restrictions controlled on the hydraulic link on the left connected respectively to the two elementary motors located on the left (44, 46) and two variable restrictions controlled on the hydraulic link on the right respectively connected to the two elementary motors located on the left side (44, 46). right (64, 66). 25 9. Device according to one of claims 1 to 8, characterized in that each restriction (212, 222) is produced by a distributor (210, 220) comprising a slide which moves between at least two positions corresponding to the the inactive state and the active state of the restriction. 10. Device according to one of claims 1 to 9, characterized in that it comprises at least one of the following components intended to control the restrictions (212, 222): a pressure sensor at the terminals of the double motors (40, 60), an inclinometer, a speed sensor of 14 front wheels, a proximity sensor or a shooting system, or even an inertial unit. 11. Device according to one of claims 1 to 10, characterized in that the restrictions (212, 222) are controlled manually by the pilot of the machine, when the latter tends to slide in the slope. 12. Device according to one of claims 1 to 11, characterized in that the restrictions (212, 222) are controlled in a combined manner manually and automatically. 13. Hydrostatic transmission method for mobile vehicles 10 using a device of the type according to one of claims 1 to 12, characterized in that it consists in controlling restrictions (212, 222) placed on a link connecting the hydraulic pump (10) respectively to the two motors (40, 60) of the second axle, when the machine is moving on sloping ground to activate the restriction 15 located on the link on the slope side connecting the hydraulic pump (10 ) to the two motors (40, 60) of the second axle. 14. Machine equipped with a hydrostatic transmission device according to one of claims 1 to 12 and / or implementing the method according to claim 13. 20