Device for the transverse traverse of vehicles

The present invention refers to a device, comprising a carriage unit, for the transverse traverse of vehicles, in particular to facilitate the manoeuvring of motor cars. Throughout the following description, the term "carriage" will be used in its widest sense, this term meaning any structure, platform or frame equipped with at least one wheel.

The aim of this invention is to provide a device which can be fitted permanently on a vehicle, which is simple and economical to manufacture and which ensures a high degree of reliability and safety in its use, even on a continuous basis. A further aim of this invention is to provide a device which can be adapted to models of vehicles or, m particular, of motor cars which may also differ greatly from each other, without it being necessary to alter the characteristics of the mechanical parts and members typical to each vehicle.

To achieve these aims, the subject of this invention is a device of the type indicated above, characterised in that the carriage unit comprises at least one wheel, is fixedly mounted underneath a vehicle and can be selectively moved from a retracted position to an extended position in which the at least one wheel of the carriage unit presses against the ground m order to raise the vehicle at least partially from the ground.

One advantage of this invention consists of the possibility of enabling the control of the device without having to sit in the driving seat, thus, for example, facilitating parking manoeuvres in tight spaces by manoeuvring the carriage from outside the motor car. A further advantage consists of the fact that, even m the event of faults or

leakages of the hydraulic system which controls the device, accidental enabling is prevented by a safety system.

Further characteristics and advantages of this invention will be indicated in the description which follows of a preferred embodiment, with reference to the attached drawings, provided merely as non-limiting examples, in which:

figure 1 is a diagrammatic side view of a motor car on which a device according to this invention is fitted; figure 2 is a diagram of the relative position, seen from above, of the wheels of the device in figure 1 with respect to the wheels of the motor car; figure 3 is an enlarged diagrammatic view, according to the arrow III in figure 1, of the device of this invention in the disabled or retracted condition; figure 4 is a diagrammatic view of the device in figure 3 in the enabled or extended condition; figure 5 is a diagram illustrating the hydraulic control circuit of the carriage unit, and figure 6 is a view of a part according to the arrow VI in figure 4.

With reference to figure 1, a motor car 10 includes a steering forecarriage 12 and a rear axle 14. A carriage unit 16 comprising two wheels 18 is fitted underneath the motor car, close to the rear axle 14. When the carriage unit 16 is in the retracted position, the rotation axes X-X of the wheels are preferably at an angle a with respect to the road surface S which basically corresponds to the inclination of the motor car with respect to the road surface when the carriage unit 16 is in the extended position, as better described below. In figure 2 it can be seen that the wheels 18a, 18b of the carriage unit are also at an angle to each other, in such a way that the intersection 0 of their rotation axes Xa-Xa and Xb-Xb preferably coincides or is close to the centre line of the transverse axis Y-Y of the forecarriage 12 of the motor car.

In more detail, as shown in figures 3 and 4, the carriage unit comprises a transverse support bar 20 fixed to the load- bearing structure of the vehicle. In the case illustrated in the figures, the support bar comprises two coupling members 22 which can be fixed onto structural parts of the vehicle. Two longitudinal members, not shown in the figures, are fixed at one of their ends to the support bar 20 and at the other end to the structure of the vehicle, in such a way as to counter the torsional motion of the bar 20. The coupling systems of the transverse bar 20 can naturally vary extensively with respect to what is illustrated, so that they can be adapted to different models of motor cars.

One end of a main rod 26 is articulated with a bracket 24 of the bar 20 while the other end leads to the wheel 18a. A hydraulic bi-directional motor 28 connected to a hydraulic circuit better described below is splined on or otherwise coupled to the axle of the wheel 18a. A double-acting hydraulic cylinder 30 is also connected to the bracket 24 and the cylinder actuator rod 32 is articulated with the central joint 34 of a knee-joint lever 36, the two arms of which 36a and 36b are hinged respectively on the transverse bar 20 and on the mam rod 26. A first lever 38 is articulated with the main rod 26 and, by means of a second lever 40, acts on one of the three articulation points of a bell crank 42, hinged in turn on the bar 20. A series of levers 44, 46 and 48 constitute a kinematic chain which joins the bell crank 42 to a secondary rod 50 which is hinged at its ends respectively to a bracket 52 of the bar 20 and to the idle wheel 18b.

Two scythe-shaped or hook-shaped elements 54 are fitted at the ends of the transverse bar 20 and oscillate with respect to an axis parallel to the bar 20, shown also in figure 6. Each scythe-shaped element is equipped with a pin 56 on which a helical spring 58 is hooked, the other end being fixed respectively to the mam rod 26 and to the secondary rod 50,

close to the wheels 18a, 18b.

One end of a link rod 62 is articulated with a central bracket 60 fixed to the bar 20 and the other end is hooked onto a spring 64 and articulated with a safety lever 66 which is in turn hinged to the articulation point of the first lever 38 with the second lever 40. At its bottom end, the spring 64 presses against a support 68 which is also fixed to the transverse bar 20.

Referring now to figure 5, the hydraulic control circuit of the cylinder 30 and of the bi-directional motor 28 comprises a tank 70 containing an incompressible fluid, for example oil. An outlet pipe 72 communicates with the mlet of a pump 74 mechanically connected to an electric motor 76. A pipe 78 connects the delivery of the pump 74 to a first three-position and four-way solenoid valve 80. In the central position 80a, the pipe 78 is joined to the pipe 82 which leads to a second solenoid valve 84, basically the same as the first one. In the two lateral positions of the solenoid valve 80, the pipes 78 and 82 communicate - in straight or crossed configuration, respectively - with the pipes 86 which enable the double-acting cylinder 30.

The two outputs of the solenoid valve 84 are connected to the pipes which enable the hydraulic motor 28, the axle 88 of which is splined directly onto the axle of the wheel 18a. An outlet pipe 90 of the solenoid valve 84 drains into the tank 70 with the possible interposition of a non-return valve 92. A safety valve 94 connects the pipes 78 and 90 in order to limit the maximum pressure of the hydraulic circuit. A wide range of variations can naturally be adopted for the hydraulic circuit while remaining withm the framework of this invention. For example, the electric motor can be replaced with a power takeoff fitted directly on the drive shaft of the vehicle, with the possible interposition of a clutch unit or with the interposition of a three-way solenoid valve on the hydraulic

circuit with selective by-pass functions of the solenoid valves. In one variation, the hydraulic circuit is interlocked with the pump of the vehicle's power steering or with another pump already installed or which could be installed in the vehicle for the on-board hydraulic services.

The two solenoid valves are controlled by an electric circuit which preferably comprises a four-way operating push¬ button, controlled by the driver: a first, stable quiescent position, a second, instable position enabling the cylinder 30, and two additional instable positions which enable the hydraulic motor 28 in the two rotation directions. End sensors of the cylinder 30, connected to the electric control circuit, are also foreseen and their function will be described below.

In normal conditions, when the motor car 10 is moving or is parked, the carriage unit is in the retracted position shown in figure 1. The electric motor 76 is de-energised and the solenoid valves 80 and 84 are in their central position. To raise the rear axle 14 of the motor car, the driver presses the push-button which activates the electric circuit and switches it to the instable activation position. The circuit carries out a check to make sure that the vehicle is not moving and then simultaneously energises the electric motor 76, which activates the pump 74, and the solenoid valve 80 which switches to the extension position of the cylinder 30. By pushing against the knee-joint lever 36, the cylinder 30 causes the lowering of the main rod 26 which, in turn, causes the rotation of the secondary rod 50 and the lowering of the wheels 18a and 18b. When the wheels 18a and 18b touch the ground S they start to raise the motor car 10, unloading the suspension of the rear wheels. To limit the travel of the suspension members, the scythe-shaped parts 54, pulled downwards by the action of the springs 58, hook onto the rear suspension members of the motor car, preventing them from expanding further and allowing the rear wheels of the motor car to be raised from the ground S. When the carriage unit 16 is fully lowered, as shown in figure

4, the axis X-X of the wheels 18a and 18b is essentially parallel to the ground S. When the cylinder 30 has reached a predetermined extended position, an end sensor returns the solenoid valve 80 to the central position 80a in order to stop the lowering of the wheels 18a and 18b.

To move the rear part of the motor car transversally, the driver moves the operating switch to one of the two instable rotation positions which correspond respectively to the activation of one or the other of the lateral positions of the solenoid valve 88. This makes the hydraulic motor 28 turn in a clockwise or anticlockwise direction, causing the corresponding rotation of the wheel 18a and thus the transverse movement of the rear part of the vehicle 10. More specifically, the rear part of the vehicle 10 executes an arc of a circle, the centre of which essentially coincides with point 0, the intersection of the axes Xa-Xa and Xb-Xb of the wheels 18a and 18b, as can be seen in figure 2.

When the driver releases the operating switch, it returns to the stable position. At this point a signal from an upper end sensor shifts the solenoid valve 80 to the position which controls the withdrawal of the rod 32 of the cylinder 30. When the upper end sensor detects that the cylinder 30 is completely withdrawn, it sends a disabling signal to the electric motor 76 and the solenoid valve 80. As they move upwards, the springs 58 close and push the scythe-shaped parts 54 upwards, releasing the rear suspension members of the motor car.

The adoption of the upper end sensor is particularly advisable since it also acts as a safety device should, for any reason, the carriage unit 16 move from the retracted position without having been activated by the driver. In such an event, the electric motor 76 and the solenoid valve 80 would immediately be activated to return the carriage unit 16 to the rest position. Furthermore, the spring 64 represents an additional mechanical safety device, preventing the carriage

unit 16 from being lowered as a result of a fault or leakage in the hydraulic circuit. In the position shown in figure 3, in fact, the spring 64 acts on the safety rod 66 according to an advantageous lever force, thus exercising a much greater thrust on the leverage of the carriage unit 16 than its overall weight.

For safety purposes, the cylinder 30 can also be fitted with a blocking valve to prevent the oil contained withm the cylinder from leaking out while in the rest position due to leakage m another pomt of the hydraulic circuit.

The version of the device described above and illustrated in the figures, comprising the electric motor 76, is particularly advantageous if one wishes to operate the device even when the motor is switched off. For example, it may be advantageous to fit a second operating switch near the rear of the motor car, accessible without having to get mto the car. In this way it is possible to move the vehicle if it should be necessary to park next to a wall or next to another vehicle in order to complete a parking manoeuvre in tight spaces. Another variation could foresee remote control of the electric motor 76 and the solenoid valves 80 and 84 by means, for example, of infrared, ultrasound, radio waves or the like.

The system which limits the travel of the rear suspension members can also be extensively modified, for example by foreseeing gπppers, tie rods and other mechanical devices connected in various ways to the carriage unit 16 by techniques which are immediately understandable by a technical expert this sector. Moreover, in the case of motor cars with adjustment and hydraulic locking of the suspension, direct control could be foreseen of the suspension hydraulic circuit by the control circuit of the device described m this invention.

As far as the mechanical construction of the carriage unit is concerned, it is obvious from the description of this

invention that the leverages illustrated in the figures can be extensively modified, both in number and in kinematic configuration. In the simplest case, when there is enough space underneath the vehicle, it would be sufficient to foresee just two rods carrying the wheels 18a and 18b, activated by one or two cylinders whose hydraulic circuits are connected in parallel to the same solenoid valve 80, or to two different solenoid valves operated simultaneously. Another variation of the device as per this invention foresees the assembly of a carriage unit close to the forecarriage of the vehicle, in addition to or replacing the carriage unit on the rear axle.

Save and except the principle of the invention, the ways in which the device can be operated and the details of how it can be constructed can naturally vary extensively with respect to what is described and illustrated, without however going beyond the scope of this invention.