FR2589419A1 - Device for controlling the guiding wheels of a vehicle - Google Patents

Abstract

Device for controlling the guiding wheels of a vehicle, for agricultural or public works use. The jacks 3a, 3b are controlled by a distributor 4 which, in the central position, immobilizes the jacks in their current state. A first manually-controlled contact 9 makes it possible to bring the wheels into the desired orientation and to keep them there. A second contact 10, controlled by the position of the wheels, is intended for the automatic return of the wheels to the "in-line" orientation.

Description

 The present invention relates to a device for controlling the orientation of the steered wheels of a machine, for example an agricultural machine, or a public works machine.

 The vehicles of the aforementioned types are most often equipped with an axle carrying steering wheels controlled by a power steering device fairly similar to that which can be seen on automobiles. To facilitate the development of such vehicles, for example to obtain a very small radius turning, or else to facilitate movement on terrain having a steep slope in a direction transverse to the direction of movement, it is known to equip one or more other axles of the vehicle with driving wheels, thus constituting a secondary steering axle.

For example, if one wishes to increase the turning facilities, provision will be made for the secondary steering wheels to pivot to the left when the main steering wheels to pivot to the right. If on the contrary, one wishes to make the machine evolve on a terrain with a steep lateral slope, the secondary steering wheels will be oriented parallel to the main steering wheels, these wheels all being oblique with respect to the axis of the machine.

 Usually, to control the secondary steering wheels, a control circuit similar or identical to the control circuit of the main direction is used, with sometimes a mechanical, hydraulic, or electronic control between these two circuits.

The complexity that results from these solutions makes their achievements costly. The large number of handling elements necessary to obtain the various configurations on the self-propelled machine: increased steering, forward shifting, etc. makes the use difficult.

 The object of the present invention is to provide a control device which makes it possible to obtain substantially the same results while being very simple, and of low cost.

 Although the device of the invention is intended mainly for controlling secondary steered wheels, it is clear that it can also be applied to main steered wheels, provided that the speed of the machine is not too high.

To obtain the above result, the invention provides a device for controlling the orientation of the steered wheels of a machine, comprising at least one jack connected to said wheels, and a distributor of fluid for feeding the jack, which has for peculiarities that
The distributor is of the electrically controlled type with three positions: a blocking position in which the cylinder is locked in position by closing its supply and discharge conduits, and two displacement positions in which the cylinder is supplied to rotate the wheels respectively to the right or to the left, the distributor being equipped with means for automatically returning it to the locked position when it receives no electric current,
and that the electric control of the distributor comprises two circuits mounted in parallel and supplied alternately by a switch: a first circuit comprising a first contactor controlled by the conductor and having three positions corresponding to the three locking and displacement positions of the distributor, and a second circuit comprising a second contactor also having three positions corresponding to the three locking and displacement positions of the distributor, this second circuit being controlled by the orientation of the wheels, so that the wheels are urged by the jack to turn to the left when they are oriented to the right, and vice-versa, and are blocked when they are online.

 According to a preferred embodiment, the second contactor comprises a movable assembly mechanically connected to a cam follower which cooperates with a cam whose movements are controlled mechanically by the pivoting of the wheels.

 According to another method, which is a little less expensive due to the absence of a cam, but a little more complicated to implement, the second contactor comprises a movable assembly whose movement is controlled by at least one electromagnet, the power supply is itself controlled by a potentiometer or a switch actuated by the pivoting of the wheels.

To explain the invention in more detail, reference will be made to practical examples of embodiment, illustrated with the aid of the attached drawings, among which
FIG. 1 is a diagram of the device with the wheels in the "in line" position,
FIG. 2 is a similar diagram of the device during a pivoting operation of the wheels to the right,
FIG. 3 is a similar diagram with the wheels in an automatic return situation to the online situation ", and
FIG. 4 is a similar view with the wheels automatically held in the right-facing position,
Figures 5 and 6 show variants of the control mode of the second contactor.

 The device described in Figures 1 to 4 comprises an axle 1 carrying wheels 2, which are orientable under the action of two cylinders 3a, 3b. Axle 1 can be a driving axle. The jacks 3a, 3b, which are single-acting jacks, and which act in opposite directions, are controlled by a distributor 4, provided with two control electromagnets 5a, 5b and with return springs 6.

In a central position M of the distributor, the two jacks 3a, 3b are blocked, their supply and discharge conduits being closed. When the magnet 5a is supplied, the distributor passes into a position or the jack 3a is supplied so as to turn the wheels to the right, then when the electromagnet 5b is supplied, the distributor is in position B, and the jack 3b urges the wheels to the left.

 The current supply of the electromagnets 5a, 5b comprises a current circuit 7, and a switch 8, which has two positions h and i in which it sends the current in one or the other of the control circuits.

The first circuit is simply formed by a first contactor 9, with three positions: M, A and B. In position A, the contactor sends current to the electromagnet 5a, while in position B, it sends of current in the electromagnet 5b. When the contactor is in the M position, the electromagnets 5a and 5b are not supplied, and under the effect of the springs 6, the distributor moves to the M position, or blocking position.

The contactor 9 automatically returns to position M when it is no longer controlled.

 The second circuit includes a second contactor 10, the moving assembly 11 of which can also take three positions, a medium position, where it does not power the electromagnets 5a, 5b, a position A where the element 5a is energized, and a position B, where the electromagnet 5b is energized. The moving element is connected to a cam follower 12, constituted by a roller which rolls on a cam 13. This cam, in the shape of a triangular sector, is pivotally mounted on the casings and can pivot under the action of a rod 14 and a lever 153 integral with the rocket of one of the wheels 2.

 Indicator lights 16a, 16b indicate whether the jack 5a or the jack 5b is supplied with electric current.

Figure 1 shows the situation when wheels 2 are locked with in-line orientation
In this situation, the switch 8 is in position i, in which it supplies the second circuit.

The first contactor 9 is not supplied, as for the second contactor 10, its movable assembly is in the middle position, in which neither of the electromagnets 5a, 5t is supplied. In these conditions, the wheels are locked in the "online" layout
Figure 2 shows the situation during a controlled maneuver for pivoting the wheels to the right (arrows A). Switch 8 has been switched to position h, in which the first contactor 9 is supplied, and this contactor is placed in the position
A in which the electromagnet 5a is supplied. The distributor is therefore in position A, and the electromagnet 3a urges the wheels to turn them to the right as indicated by the arrows.

 FIG. 3 shows the situation as it presents itself when it is desired to return the wheels to the "in line" orientation. The switch 8 has returned to position i in which the second contactor 10 is energized. The cam 13, which is located away from its middle position, has moved the mobile assembly of the second contactor 10 to bring it into position B. The electromagnet 5b is therefore supplied, the distributor 4, being in position B, feeds the actuator 3b, which biases the wheels to the left until they return to the middle position (arrows B). When this middle position is reached, the cam 12 will have returned to its middle position, so that the moving assembly 10 of the second contactor 9 will return to the middle position where neither of the two electromagnets 5a, 5b is supplied.

 It will be noted that, to go from the situation in FIG. 2 to the situation in FIG. 3, it was sufficient to switch the switch 8 and release the contactor 9, which automatically returns to position M. If this contactor had not no automatic return when the switch 8 was returned to the h position, the contactor 9 still being in the A position, the electromagnet 5a would have been immediately energized, and the wheels would be immediately distributed to the right, this which is to be avoided.

 FIG. 4 shows the situation in the case where it has been decided to maintain the wheels in the position oriented to the right after an operation such as that of FIG. 2. In this case, it suffices, leaving the switch 8 in the position h, to let the contactor 9 return to the position M. In this situation, the electromagnets 3a, 3b are no longer supplied, and the wheels are locked in their present position. If it is subsequently desired to return from the situation in FIG. 4 to that of FIG. 1, it will suffice to pass the switch 8 to the position i *.

 FIG. 5 shows a variant of the control of the contactor1 Two electromagnets 20a, 20b are capable of moving, in opposite directions, the moving element II. These electromagnets 20a, 20b are controlled respectively by two linear potentiometers 21a, 21b, which are integral with the cylinders 3a, 3b at one end, and at the other end, the potentiometers 21a, 21b are connected by the intermediate a slide 22a, 22b to the rod of the same cylinders 3a, 3b. Depending on the orientation of the wheels, one or other of the potentiometers is stressed, and provides a potential difference in proportion to its elongation. It is conceivable that the moving assembly remains in its middle position when neither neither of the potentiometers 21a, 21b is supplied, or else they are both supplied at the same time. On the contrary, if only one of the two potentiometers is supplied, which corresponds to an orientation different from the "in line" orientation, the moving element is moved in the corresponding direction.

It is possible to provide only one potentiometer; in this case, the slide is eliminated, and a return spring is provided for the moving element 11. The proportional output of the electromagnet controls a corresponding movement of the moving element, that is to say that for the maximum and zero potential differences, the moving assembly occupies opposite positions, while for the average potential differences, it occupies the central position.

 FIG. 6 shows a device similar to that of FIG. 5, but in which the potentiometers 21a, 21b have been replaced by switches of type 1, limit switches 23a, 23b, carried by the body of the corresponding jack 3a, 3b, and which are moved upwards, in the figure, by a rod 24a, 24b, integral with the cylinder rod. The operation is substantially the same as that which has been described above. The devices described in Figures 5 and 6 use simpler components but lower cost than the cam described with reference to Figures 1 to 4, however they introduce a small additional complication, due to the presence of additional electrical circuits .

 One could be tempted to replace contactor 10 directly with two "limit switch" contactors controlled by a flexible blade, itself driven by the movements of the wheel. This solution, which appears much simpler, however has the drawback of having a relatively fragile device near the wheels, and in a place subject to impacts or splashes of mud or the like. This is why this solution was not retained in the example described.

Claims (3)

 1. Device for controlling the orientation of the steered wheels of a machine, comprising at least one jack (3a, 3b), connected to said wheels (2), and a distributor (4) for supply fluid to the jack, characterized in that  the distributor is of the electrically controlled type with three positions: a blocking position (M) in which the jack is locked in position by closing its supply and discharge conduits, and two displacement positions (A, B) in which the cylinder is powered to rotate the wheels respectively to the right or to the left, the distributor being equipped with means (6) for automatically returning it to the locked position when it receives no electric current, and in that the electric control of the distributor comprises two circuits mounted in parallel and supplied alternately by a switch (8), a first circuit comprising a first contactor (9) controlled by the driver and having three positions corresponding to the three locking and displacement positions of the distributor , and a second circuit comprising a second contactor (10) also having three positions corresponding to the three locking and displacement positions of the distributor, this second circuit being controlled by the orientation of the wheels, so that the wheels are urged by the jack to turn to the left when they are oriented to the right and vice versa, and are blocked when they are "in line  2. Device according to claim 1, characterized in that said second contactor (10) comprises a movable assembly (11) mechanically connected to a cam follower (12) which cooperates with a cam (13) whose movements are controlled mechanically by swivel the wheels.  3. Device according to claim 1, characterized in that said second contactor (10) comprises a movable assembly (11) sleeps. Re displacement is controlled by at least one electromagnet (20a, 20b) whose supply is itself controlled by a potentiometer (21a, 21b) or by a switch (23a, 23b) actuated by the pivoting of the wheels ( 2).