FR2558779A1 - STEERING WHEEL BRIDGE FOR VEHICLES, PARTICULARLY FOR ROAD AND ALL TERRAIN WALKING - Google Patents

Abstract

STEERING WHEEL BRIDGE FOR VEHICLES, ESPECIALLY FOR WALKING ON THE ROAD AND ON ANY TERRAIN, CHARACTERIZED BY THE FACT THAT IT INCLUDES A SHAFT 8 ACTIVATED BY A DRIVE SHAFT OF THE VEHICLE BY MEANS OF A TORQUE OF CONICAL GEARS 12A, 12B, THIS SHAFT 8 COUPLING TO THE HALF-SHAFTS 14A, 14B CARRYING THE WHEELS 10A, 10B BY MEANS OF TWO INDEPENDENT CLUTCHES 15A, 15B THAT CAN BE CONTROLLED, THE ENGAGEMENT AND DISCHARGE OF ONE OF THESE CLUTCHES OR OF THE TWO CAN BE EXECUTED BY MANUAL MEANS AND BY AUTOMATIC MEANS OF CONTROL, SENSORS SENSITIVE TO THE MOVEMENT OF THE WHEELS AND TO THE TRACK OF THE VEHICLE, PROVIDED AND DESIGNED TO ACT ON AUTOMATIC MEANS OF CONTROL IN RELATION TO MARKET REQUIREMENTS.

Description

Vehicles intended to circulate on all land-

  rains, or in any case on low adhesion grounds

  Rence, particularly tractors for agricultural use, require that in the event of loss of grip of the rear drive wheels, traction is also applied to the steered wheels, generally the front wheels, so as to allow advancement even under difficult conditions. For this purpose, there is a shaft connected to the gear change by a clutch or similar means and

  who controls a steering front axle fitted with a differential

  clean tiel which, in turn, must be of the type that can be blocked or self-locking, the whole being very complex

and expensive.

  The object of the invention is therefore to provide a bridge for steered wheels in which there is no need for a locking differential ensuring traction by one or both wheels, even in terrain conditions at low grip, and which allows to take correctly the curves on hard ground by ensuring that the wheels which follow courses of different radius

  rotate at different speeds.

  Another object of the invention is to provide an engine front axle for vehicles in which traction is usually supplied to two wheels to assist the normal traction applied to the rear wheels and can be supplied to only one of the front wheels during the curve, or to none of these, for example in the

walking on the road.

  These results, as well as others, are obtained by the invention which provides a steered wheel bridge for vehicles particularly for walking on the road.

  and on all terrains, characterized by the fact that it

  takes a shaft actuated by a motor shaft of the vehicle by means of a couple of bevel gears, this shaft coupling to the half-shafts carrying the wheels by means of two independent clutches which can be controlled, the engagement and disengagement of one or both of these clutches being capable of being executed by manual means and by automatic control means, sensors sensitive to the movement of the wheels and to the path traveled by the vehicle being provided and designed to act on the automatic means of related order

  with predetermined walking requirements.

  The clutches ordered can be friction clutches or toothed clutches provided

  remote control means and these means of

  remote control can be electromagnetic means

  ticks, hydraulic or mechanical, depending on the use requirements of the vehicle for which the bridge is intended

  and the relative mechanical dimensions.

  In a particularly preferred embodiment,

  the invention, the clutches ordered are

  formed by electromagnetic friction clutches

  ticks each having a fixed coil attached to the outer deck body, this coil acting

  on a ring, or again, to make sure that the an-

  neau tightens a pack of friction discs, they can be alternately secured to the shaft and. of one of the half-shafts carrying the wheels, these clutches being released and the corresponding wheels being idle in

  the absence of electrical supply to the coils.

  Controlled clutches can be maintained

  under conditions of engagement during normal walking

  male and temporarily released, automatic means

  being actuated by the steering device

  tion of the vehicle or subject to it and commander

  the release of the clutch which connects one of the half

  trees to the shaft powered by the motor shaft during

  running a curve; in particular, it is ap-

  property that the automatic control means are actuated by the vehicle steering device

  to control the release of the corresponding clutch

  laying on that of the half-shafts which carries the external wheel

  lower than the curve described by the vehicle. In addition to the automatic control means, manual means are provided for the independent control of engagement and independent disengagement of one

clutches or both.

  In an appropriate embodiment, the bridge according to the invention comprises sensors detecting the speeds and / or the differences in speed of the rear driving wheels of the vehicle, provided with a differential, these

  sensors acting on the automatic means of

  mande, determining the engagement of clutches when prescribed speeds or speed differences of the rear wheels are exceeded, indicating slippage

of these wheels.

  With any of the clutches provided, it is advantageous that in the absence of power to the control means for accidental causes, the clutches

remain in the released position.

  Clutches can be released permanently

  with manual control, so that the two half

  bridge trees go crazy, especially in the case of road walking; in addition, they can be permanently engaged with manual control and exclusion of automatic control means, providing constant traction on both wheels of the bridge, particularly for walking on all terrains, on

  uneven or limited grip terrain.

  Various other features of the invention

  moreover emerge from the detailed description which

  follows. An embodiment of the object of the invention is shown, by way of nonlimiting example, at

attached drawing.

  Fig. 1 is a general diagram of an agricultural tractor

  school equipped with a front wheel drive axle according to the

  vention. Fig. 2 is a detailed drawing in section of

  the structure of the invention in an exemplary embodiment.

  Fig. 3 is an electrical actuation diagram

of the device.

  Fig. 4 shows a behavior diagram of a vehicle provided with a device according to the invention, in

a small radius curve.

  Figs. 5 and 6 are diagrams corresponding to FIG. 4, the curve having respectively a mean radius

and tall.

  As seen in fig. 1, it is a vehicle

  all terrain cule 1, for example an agricultural tractor, having a motor 2 connected, via a gear change and clutch group 3 and a shaft 4, to a rear axle 5 carrying a pair of drive wheels 6. To allow the curves to be taken correctly, the rear axle 5 includes a differential 7,

  possibly of the type that can be blocked or self-

  blocking, for traffic on all terrains.

  From the gear change and clutch group 3 also comes out a motor shaft 8 which provides the movement

  to the front axle 9 carrying the steered wheels 10a, 10b.

  The front axle 9 is constituted by an external body

  11 inside which is placed the driving torque

  conical grenages 12, composed of the pinion 12a and the

  crown 12b, the latter carrying a shaft 13.

  The shaft 13 is connected to the two half-shafts 14a, 14b by a pair of controllable clutches 15a, 15b,

  contained in the outer box 11.

  A preferred embodiment of the invention

  is shown in detail in fig. 2 and provides for the use

  electromagnetic friction clutches.

  As illustrated in the drawing, the end of the shaft 8 carries the pinion 12a and is supported by a rotating support 16 inside the tubular element 16a, in turn supported by the structure of the vehicle,

known manner and not shown.

  The outer box 11 is provided with lateral parts 11a, 11b inside which are placed the coils 17a, 17b of the electromagnetic clutches a, 15b and the supports 18 of the shaft 13, carrying the

crown 12b.

  Each end of the shaft 13 carries a crown 19 which has an external toothing 19a to which

  mate, by the corresponding internal teeth

  dantes, the friction discs 20 alternating with the friction discs 21, in turn coupled by their external teeth to the internal teeth 22 of the rim element 23 to which is connected, by the profile

  fluted 24, one of the half-shafts 14.

  Around each coil 17a, 17b is arranged a

  magnetic core 25 integral with the shaft 13, with inter-

  position of a reduced air gap; this magnetic core 25 has annular openings 26 and similar annular openings 27 are formed on the friction discs 20 and 21; the magnetic flux generated by the coil 17 can close on the armature 28 in material

  ferromagnetic, internally toothed and capable of

  smooth on the teeth 19a so that this frame 28 clamps the friction discs 20 and 21 between them and against the core 26, thus transmitting the movement to

  half trees 14a, 14b. In the absence of electrical supply

  sticks of the coils 17, the friction discs 20 and 21

  move away, leaving the half-trees 14a, 14b crazy.

  This execution is of particular construction-

  economical, the maximum force exerted by the coil 17 being necessary to allow the friction transmission between the discs 20 and 21 of the traction torque applied to the half-shaft. This torque must, in fact, be exerted in minimum airgap conditions, therefore when the discs 20 and 21 are in contact with each other and with the core 25 which can wrap the coil 17 with minimal, limited free spaces.

  only by machining tolerances.

  In this way is produced a vehicle with traction on all four wheels, in which it is possible, by actuating the clutches 15, to disconnect the traction from the two wheels and it is also possible to disconnect it for only one of these, which makes it possible take curves without requiring the presence of differentials which should also be provided with a lock. The clutch release control corresponding to one of the wheels can be performed automatically, in accordance with the direction of the vehicle, with a device representing

schematically in fig. 3.

  As illustrated in this drawing, there are plans to install

  ler, on the direction S of the vehicle schematically shown, a pair of switches 29, 30 open respectively in the right and left direction, by means of suitable cams connected to the steering device; these switches control, when they are actuated, the opening of the supply circuit of the coils on the right 17b and on the left 17a respectively, so that the wheel outside the curve is

driven mad during management.

  In addition, other switches 31 and

  32, normally open, placed on the res-

  power supply for coils 17b, 17a and an inter-

  breaker 33, normally closed, which precedes the inter-

breakers 29, 30.

255S779

  These switches allow, when desired

  exclude automatic operation controlled by the device

  positive direction, to control as required the engagement and disengagement of clutches 15. Indeed, by opening the three switches-31, 32, 33, the traction is permanently disconnected from the two wheels of the front axle, for example in the case of walking on the road where it is not necessary. Closing one or both of the switches 31 and 32, while the switch 33 remains open, also makes it possible to connect the traction to one or both of the front wheels, regardless of the route followed, on the

driver control.

  The switches 31, 32, 33 mentioned may be independent and manually controlled, so as to allow the driver to choose the traction conditions most suitable for the terrain traveled; or again, these switches can be interdependent and also have automatic controls, for example

  actuated by speed or differential sensors

  rear wheel speed references, so that when one of these is subject to slippage, front-wheel drive is applied to the wheel on the opposite side, which can easily be on solid ground, or both ; this automatic system can also, when it does not detect significant differences in the speed of rotation of the rear wheels, due to unforeseen losses of grip of one of them, automatically ensure the disconnection of the traction on the

  front wheels, with a significant saving of power.

  The behavior in curves is indicated in fig. 4, 5 and 6 which schematically represent an all-terrain vehicle, such as for example an agricultural tractor, having a rear axle 5 and rear wheels 6 and a steerable front axle 9 carrying the wheels

before 10a, 10b.

  Fig. 4 shows the case where the vehicle is in a curve of reduced radius R1, relative to the path described by the axis of the rear axle 5 of the vehicle, which is provided with a usual differential, possibly with the possibility of blocking. As can be seen in the drawing, the inner front wheel 10a describes an arc of radius R2, larger than R1. So, in conditions of perfect grip on the ground,

  this is called to rotate at a peripheral speed

  rique higher than the average speed of translation of the vehicle in curve, corresponding to the movement the

along the arc of radius R1.

  In fig. 5 is represented the diagram relating to a curve of average radius, in which the front wheel has described an arc of radius R2 'practically equal to the radius R1' described by the axis of the rear axle 5. In this case, with perfect grip on the ground, the peripheral speed of the inner front wheel 10a coincides with the average forward speed, given that they relate to movement on the same arc, of radius R1 '= R2' In FIG. 6, with a curve with a large radius R1 ", the inner front wheel 10a must travel through an arc with radius R2" less than R1 "and must therefore rotate at a peripheral speed less than the average speed of advance of the vehicle along the 'arc of radius R1 "but practically little different from it, given the small difference between R1" and R2 "The outer front wheel 10b advances, in the three cases shown, along arcs of respective radius R3, R3 ', R3 "which are always greater than the corresponding average radius R1, R1', R1" and therefore has a speed

  device greater than the average forward speed

  vehicle cement. Since the transmission of

  movement at the front wheels, intended for correct walking

  straight in a straight line, causes the front wheels to turn at a peripheral speed corresponding to the average speed of translation of the vehicle, which, in a curve, is intermediate between the two speeds of the rear wheels, connected together by a differential, if the traction is applied before the inner wheel inside the curve, in theory, you can have a correct execution of the curve only in

  cases similar to that of fig. 5.

  In wider curves, this front wheel

  interior 10a will rotate at slightly higher speed

  higher than the optimal speed while, in narrower curves, the wheel 10a will have a lower speed

at the theoretical value.

  However, these differences are very limited and

  completely negligible in walking on all land

  roads, on uneven ground, in particular in the presence of oscillations and unevenness of the ground and with discontinuous contact of the wheels with the ground. However, in the case of particularly narrow curves, where the reduced speed of the inner, driving front wheel,

  has the effect of slowing the movement, we can disconnect

  expensive traction on it too, leaving it crazy; the traction on this wheel may however be

  restored in the event of loss of adhesion

  rence of a rear wheel, so when said front wheel can make its own contribution to traction the

along the curve.

  This disconnection can also be operated automatically.

  tically, for curves of radius less than one

  appropriate value, with electric controls ap-

  applied for example to the steering of the vehicle and automatic control devices, similar to those

  that we have already described, can intervene, to restore

  blir the traction on the front wheels. So we created a device that allows a simple realization of a

  engine front axle and which, moreover, lends itself to multiple

  many actuation possibilities, both manual and automated, to select the most appropriate traction conditions for each terrain. In some applications, in addition, one can also use a device according to the invention for rear axles, which eliminates, for these too, the conventional differential. In such a case, on a curve, we could simultaneously engage the auxiliary clutches

  to the outer rear wheel and the inner front wheel

  higher, with speeds that are not too different

  as you can see by fig. 4, 5 and 6.

  The bridge according to the invention has been described in connection with cases in which it is disadvantageous that in the event of an anomaly, the traction remains connected to the two wheels of the front axle; on the other hand, in cases where it is preferable, clutches of various types can be used, kept normally engaged, for example at

  means of springs, and released on command.

  Multiple variations can be made to what is described above, in particular for adaptation to the different possible types of clutch, friction or toothed, which can be used. For example, in the case of hydraulically controlled clutches, a hydraulic or electro-hydraulic circuit will be required, performing the same operations as the electrical circuit described.

  above, and similarly in the case of clutches with

  mechanical control for which provision may be made - various connections having the same purpose, without leaving

of the scope of the invention.

1 1

Claims (10)

  1 - Steering wheel axle for vehicles   especially for walking on the road and on all types of   rains, characterized in that it comprises a shaft (8) actuated by a motor shaft of the vehicle by means of a pair of bevel gears (12a, 12b), this shaft (8) mating with the half-shafts (14a, 14b) carrying the wheels (10a, 10b) by means of two independent clutches (15a, b) that can be controlled, the engagement and disengagement of one or both of these clutches that can be executed by means manuals and by   automatic control means, sensitive sensors   the movement of the wheels and the trajectory   run by the vehicle being provided and designed to act on the automatic control means in relation to   predetermined walking requirements.   2 - Bridge according to claim 1, characterized in that the clutches (15a, 15b) controlled are friction clutches provided with control means to distance.   3 - Bridge according to claim 1, characterized in that the clutches (15a, 15b) controlled are   toothed clutches provided with remote control means tance.   4 - Bridge according to one of claims 1 to 3,   characterized in that the remote control means are electromagnetic, hydraulic means   or mechanical, depending on usage requirements.   - Bridge according to one of claims 1 to 4,   characterized by the fact that the controlled clutches (15a, 15b) are constituted by electromagnetic friction clutches each having a fixed coil (17a, 17b) integral with the external body (11) of the bridge, this coil acting on a ring, or again, to make the ring (25) grip a bundle   friction discs (20, 21) they can be alternated   natively integral with the shaft (13) and one of the half-shafts (14a, 14b) carrying the wheels (10a, 0lob), these clutches being released and the corresponding wheels being idle in the absence of electrical supply coils.   6 - Bridge according to one of claims 1 to 5,   characterized by the fact that the controlled clutches (15a, 15b) can be maintained in engagement conditions during normal operation and temporarily released, the automatic control means being actuated by the vehicle steering device or controlled by it and controlling it the release of the clutch which connects one of the half-shafts (14a, 14b)   to the shaft (13) actuated by the motor shaft during the exe cution of a curve.   7 - A bridge according to claim 6, characterized in that the automatic control means are actuated by the vehicle steering device to control the release of the clutch (15a or 15b) added to that of the half-shafts (14a or 14b) who wears   the wheel outside the curve described by the vehicle.   8 - Bridge according to one of claims 1 to 7,   characterized in that manual means are provided for independent control of the engagement and disengagement of one of the clutches (15a, 15b) or both.   9 - Bridge according to one of claims 1 to 8,   characterized by the fact that it comprises sensors detecting the speeds and / or the differences in speed of the rear driving wheels (6) of the vehicle, provided with a differential, these sensors acting on the automatic control means, determining the engagement clutches (15a, 15b) when speeds or differences   rear wheel speed limits (6) are exceeded   sées, indicating a slippage of these wheels.   - Bridge according to one of claims 1 to 4,   characterized in that in the absence of supply to the control means for accidental causes,   the clutches (15a, 15b) remain in the released position.   11 - Bridge according to one of claims 1 to 10,   characterized by the fact that the clutches (15a, 15b)   can be permanently released with manual control-   the, driving the two half-trees (14a, 14b) of the   bridge, especially in the case of road walking.   12 - Bridge according to one of claims 1 to 11,   characterized in that the clutches (15a, 15b) can be permanently engaged with manual control   and exclusion of automatic control means,   constant traction on both wheels (10a, 10b) of the bridge, especially for walking on all   terrain, on uneven or limited grip terrain.