Abstract:
A tracked vehicle is provided for the transportation of loads and/or the supply of energy to areas having difficult access or to dangerous regions. The tracked vehicle is supported by an assembly of four banks of tracks, each driven by an independent hydraulic drive motor and directionally orientable. The vehicle includes an electronic control device for differential powering the four tracks in accordance with the distance travelled by each of the tracks.

Description:
FIELD OF THE INVENTION 
     The present invention concerns a telecontrolled four-track vehicle for the transportation of loads and/or supply of energy in areas of difficult access or dangerous for man, with no one on board. 
     DESCRIPTION OF THE RELATED ARTS 
     All-terrain vehicles are already well-known, and are capable of moving on uneven surfaces, and their track laying gear is constituted of four tracks. 
     The disadvantages of these vehicles are: 
     they necessitate the presence of at least one driver for the piloting of the said vehicle; and 
     they do not offer, therefore, any security for the life of the personnel, on board, embarked in order to accomplish dangerous tasks. 
     Such types of vehicle, for example, are described in document EP-A-0,252,674, and they have, moreover, an additional number of disadvantages such as: 
     they must provide for at least two energy supply centers, one in order to ensure the movement of the vehicle, and the other to allow the tools and the machinery on board to be driven; 
     they necessitate the use of at least two hydraulic pumps; 
     the difficulty in synchronizing the hydraulic motors, due to the manual management of the differentials and due to the fact that these pumps have fixed output and that the motors are mounted in parallel; 
     bad surface tracking by the track laying gear; and 
     their mediocre maneuverability on very rough surfaces. 
     The main object of the present invention is to rectify the above-mentioned disadvantages and insufficiencies of present all-terrain vehicles. 
     SUMMARY OF THE INVENTION 
     According to the invention, this object is achieved by deploying either a procedure or a device according to which the vehicle is supported and moved by an assembly of four independent banks of tracks, at least two of which constitute the front train or the rear train of the vehicle, and are orientable, the vehicle being remarkable by the fact that it comprises an electronic device for the differential piloting of the four tracks, this electronic device determining the speed of each track according to the following: the track position; to whether the track is orientable or not; to the geometry of the vehicle; to the set point of speed (V0); and the steering angle of the orientable train. 
     According to another characteristic arrangement, only one energy center supplies, simultaneously or otherwise, the drive of the vehicle as well as the tools embarked on board of the vehicle. 
     The vehicle with independent tracks according to the invention has the following main advantages: 
     of permitting the movement of loads in difficult access zones such as surfaces with a slope more than 40°; 
     of enabling the energy supply of a wide range of tools; 
     of enabling the security of the driving personnel; 
     of allowing, thanks to its reduced weight, the heliwinching of the vehicle; and 
     of being able to be used in a number of fields such as: public works, mountainous works, forest works, agricultural works, petro chemicals, civil protection, military applications, etc. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objects, characteristics, and advantages that have been mentioned above and others, will be clearer from the description that follows, and from the annexed drawings to which: 
     FIG. 1 is an elevational view of the vehicle equipped with four independent tracks according to a first embodiment of the invention. 
     FIG. 1a is a semi cutaway side view of FIG. 1. 
     FIG. 2 is a planar view of FIG. 1. 
     FIG. 3 is a diagrammatic view illustrating an example of articulation of the train of the front tracks. 
     FIG. 4 is a diagrammatic view illustrating the composition of the bank of tracks. 
     FIG. 5 is a layout of an embodiment of a hydraulic subsystem. 
     FIG. 6 is a diagrammatic view of the entire control-check device. 
     FIG. 7 is a detailed diagram of the electronic control circuits of the tracks. 
     FIG. 8 is a diagram of the principle of a closed loop automatic control system. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereafter is described in order: 
     the mechanical and kinematic conception of the vehicle; and 
     an embodiment of the energy subsystem; 
     the electric control-check device. 
     MECHANICAL AND KINEMATIC CONCEPTION OF THE VEHICLE 
     As is shown in FIGS. 1 and 2, the vehicle with independent tracks according to the invention comprises a chassis supported by four tracks 11a-11b, 12a-12b, at least two of which constitute the front train or the rear train of the vehicle, are orientable, the latter being constituted, preferably of two tracks 11a, 11b of the front drive. Each track is moved by an independent hydraulic motor. 
     The chassis of the vehicle is composed of a square or any other shaped central girder 1, on which an assembly of frames 2 that receives the load board 3 comes to rest. 
     At its rear section, the chassis supports a diesel motor 4, for example of 46 CV, mounted on a rubber, or any other shock absorber 5. 
     A case of hydraulic oil 6, for example of a capacity of 110 liters, rests on the central girder, at the rear. A compartment 7 that is supposed to hold the electric equipment and the batteries 8 is provided for in the front. 
     A cylindrical tube 9 is affixed dependently to the central girder at the rear, in its lower part. It acts as a support to the two rear track banks. A known device enables the rear path of the vehicle to be changed, that is to say, it enables the separation between the tracks of the rear train of the vehicle. 
     The central girder is through-cut perceptibly at its front quarter and supports the steering bush 10. 
     FIG. 3 shows an example of the articulation of the front track train. The illustrated layout includes: 
     a vertical axis 13 allowing the direction-wise orientation of the front two tracks; 
     a longitudinal axis 14 allowing contact to be maintained with the ground in case of a sharp lateral gradient; 
     transverse axes 15a and 15b allowing the longitudinal tracking of the surface; and 
     the hydraulic jacks 16a and 16b controlling the steering of the front train. 
     As is shown in FIG. 4, each tracked bank is constituted of a chassis made of mecano-welded sheet 17. The chassis supports, in the front, axis 18 of chain wheel 19. In its rear section, two scallopings in the shape of an &#34;U&#34;20 lie horizontally, and serve as sliding rack into which glide two bearings 21 that support the axis of the rear roller 22 of the track bank. These two bearings ensure track tension, with the help of a screw-bolt system 23. 
     A hydraulic motor 24 located in the front quarter of the bank drives chain wheel 19 via a chain 25 and a sprocket or a ring 26 dependent on the chain wheel. A sprocket 27 whose position can be adjusted, ensures the tension of the chain. 
     Chain wheel 19 drives track 28. 
     The bogies 29 on which rollers 30 are fixed allow the track to maintain permanent contact with the ground. 
     A roller 31 allows the track not to drift at its upper parts. 
     EXAMPLE OF EMBODIMENT OF THE ENERGY SUBSYSTEM 
     According to the invention, the energy center of the vehicle is used in order to ensure, both together or separately, the propulsion of the vehicle, that is to say, the supply of the hydraulic motors 24 (FIG. 4) ensuring the drive of the bank of tracks, and the functioning of the tools on board the said vehicle (for example: control arm, slicing lathe, water pumps, water jets, perforators, hammers, etc.). 
     FIG. 5 shows an embodiment of a hydraulic subsystem and of the electro-mechanical automatic control organs, that ensure: 
     the conversion of the mechanical energy of diesel motor 4 (FIGS. 1 and 2) into hydraulic energy by driving a single pump 52 whose pressure and output is automatically regulated, and which is therefore capable of ensuring, both the drive of the rolling organs of the vehicle and that of the diverse tools that may equip the same, according to its destination, and 
     the distribution of the hydraulic energy produced by pump 32 through a selector 33, either towards the translation motors 24, or towards the external equipment plugs 34, or towards both of them at the same time. 
     This device or subsystem also includes especially: 
     two filters that are supposed to eliminate the impurities of the hydraulic fluid, that is: 
     a high-pressure filter 35; 
     a low-pressure filter 36; 
     a circulation valve 37 that allows the diesel motor to be started with a hydraulic pump that is not under pressure; 
     an electric contactor 38 that does not allow the motor to be started without valve 37 being in an open position; 
     a security valve 39 that allows excess pressure in the hydraulic circuit to be avoided (225 bars); 
     a pressure regulator 40 that, when selector 33 is in a position to allow the external tools to be supplied, makes the hydraulic pressure fall, for example to 150 bars; 
     four proportionate electro-distributors 41 that feed the hydraulic motors 24 of the tracks according to the control current applied to the solenoidal winders of the electro-distributors; 
     an electro-distributor 42 with two working positions (left, right) and a resting position, that allows the two steering jacks 16a, 16b of front track drives 11a and 11b to be controlled; and 
     an electro-distributor 44 that allows the control jack of brake 45 of the said vehicle to be piloted. 
     ELECTRIC CONTROL-CHECK DEVICE 
     FIG. 6 is a general view of the control-check device. 
     The difficulty in controlling the four independent tracks rests in the fact that they have different speeds when the vehicle is taking a turn. 
     If V0 = base speed, the respective speeds of the tracks are proved to be: 
     front interior track at a turn 
     
         V1 =V0 (1 -A ×SIN (D)/2 ×E); 
    
     front exterior track at a turn 
     
         V2 =V0 (1 +A ×SIN (D)/2 ×E); 
    
     rear interior track at a turn 
     
         V3 =V0 (Cos (D) -B ×SIN(D)/2 ×E); 
    
     rear exterior track at a turn 
     
         V4 =V0 (Cos (D) +B ×SIN(D)/2 ×E) 
    
     wherein in which of the formulas: 
     A = Distance between chain wheels of front tracks; 
     B = Distance between chain wheels of rear tracks; and 
     E = Axle base and 
     D = Steering angle. 
     FIG. 7 represents an electronic card that allows the set point of the electronic signals to be generated from the proportionate control electro-valves, according to the set point of speed V0 and the steering angle &#34;D&#34;. 
     The composition of this electronic card and its working principles are the following: 
     A potentiometer 46 generates voltage at point &#34;F&#34;, that is equal to the angle of orientation of the front drive &#34;D&#34; multiplied by the set point of speed V0; 
     A resistance divider bridge 47 allows a voltage equal to V0 (D ×A)/(2 ×E) to be had at point &#34;G&#34;; 
     A resistance divider bridge 48 allows a voltage equal to V0 (D ×B)/(2 ×E) to be had at point &#34;H&#34;; 
     A rectifier circuit 49 followed by a divider bridge 50 allows a voltage equal to the absolute value of D/4 multiplied by the set point of speed V0 to be had at point &#34;I&#34;; 
     Circuits 51 allow the addition or subtraction of unit values to signals from point &#34;G&#34; and &#34;H&#34;; 
     An integrator 52 at the lead of S1 for which a signal equal to the following can be had: 
     S1 =V0 (1 -(A ×D)/(2 ×E)); 
     An integrator 53 at the lead of S2 from which a signal equal to the following can be had: 
     
         S2 =V0 (1 +(A ×D)/(2 ×E)); 
    
     An integrator 54 at the lead of S3 from which a signal equal to the following can be had: 
     
         S3 =V0 (1 -ABS(D)/4 -(B ×D)/(2 ×E)), 
    
      and 
     An integrator 55 at the lead of S4 from which a signal equal to the following can be had: 
     
         S4 =(1 -ABS(D)/4 +(B ×D)/(2 ×E)). 
    
     Signals S1, S2, S3 and S4 are respectively the control signals of the proportionate electro-valves or the proportionate electro-distributors of the tracks: 
     Front left (S1); 
     Front right (S2); 
     Rear left (S3); and 
     Rear right (S4). 
     It is easy to verify by calculation that these signals S1, S2, S3 and S4 &#34;approximate&#34; or approach the values of speeds V1, V2, V3 and V4. The errors are less than 5% for steering angles less than 35 degrees. 
     The electronic device that we have just described allows the differential piloting of the four tracks, and takes into account the real distance travelled by each of them. 
     FIG. 8 details the composition and the working principles of a closed loop automatic control system for the speed of the tracks. 
     A proximity detector 56 located on each track bank, in front of the chain wheel, generates an alternative voltage &#34;J&#34; at each passage of a tooth of the chain wheel or of the drive ring or sprocket 26 (FIG. 4) of the latter. 
     A voltage frequency convertor 57 generates a continuous voltage &#34;K&#34; proportionate to the speed of rotation of the chain wheel. 
     A comparator circuit 58 calculates the error signal L between the set point voltage M and measurement K: 
     
         Error (L) =M-K 
    
     An adder circuit 59 generates a control voltage &#34;N&#34; that pilots the proportionate servo-valve 41 (FIG. 5) of the train of the corresponding track. 
     The advantage of this device, is that, in case a track loses contact with the ground, it does not run light by absorbing all the hydraulic output of the pump. Actually, if K is greater than M, L will be negative and, control signal N will be diminished, and thus ensure the slowing down of the track. 
     The telecontrolled tracked vehicle controlled automatically and moves with a lot of flexibility with each drive track receiving all the power that it can use can be telecontrolled either via a cable or via a classic radio-controlled device.