Electrically propulsed vehicle

(54) REMARKS Vehicles with electric propulsion (56) QUOTE PUBLICATIONS:

EP Al 0 417 326, JP A 2002 010 405 (57) SUMMARY. p_ord_on (JQ_j i00) having two or more wheel pairs (30, 31) comprising at least one drive wheel pair.

Which vehicle is so arranged that all wheels on its right and left sides always follow the same wheel track when it is stated that the rotational frequency is individually controllable for each drive wheel, that the vehicle includes a steering angle sensor (20,260H, 260V)) which records the steering angle of the vehicle, and that the relative rotation frequency of the drive wheels is determined by the registered steering angle. The invention also relates to a drive shaft arrangement (300) for such a vehicle.

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The numbers in parentheses indicate the INID code.

526 740

Summary

Vehicles (10, 100) having two or more wheel pairs (30, 31) comprising at least one drive wheel pair. Which vehicle is so arranged that all wheels on its right and left sides always follow the same wheel track when it is stated that the rotational frequency is individually controllable for each drive wheel, that the vehicle includes a steering angle sensor (20, 260H, 260V)) which records the vehicle's steering angle, and that the rotational frequency of the drive wheels is determined by the registered steering angle. The invention also relates to a drive shaft arrangement (300) for such a vehicle.

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The present invention relates to a vehicle with two or more wheel pairs, and more particularly to a vehicle so arranged that all wheels on its right and left sides always follow the same wheel track when it is driven.

Background of the invention

Commercially available waist-controlled vehicles, such as forestry machines and loaders, are usually equipped with conventional mechanical and / or hydraulic drivelines. In such vehicles, the power is transferred from an engine to the drive wheels via an arrangement of axles, hydraulics and gears. Such arrangements are often very complicated, heavy and expensive to manufacture, while requiring extensive maintenance. Furthermore, a differential gear must be arranged between the two drive wheels to enable the vehicle to be swiveled. However, in order to achieve acceptable accessibility, for example in difficult terrain, the drive line must be equipped with a differential lock / brake arrangement which counteracts the differential gear, for example if one of the drive wheels loses the bracket. Such locking / braking arrangements make the mechanical drive line even more complicated, while greatly reducing the maneuverability when activated. Furthermore, the complicated powertrain leads to considerable power losses, which in turn leads to increased fuel consumption.

The disadvantages of mechanical drivetrains are particularly apparent in connection with machines with more than two driving wheels, such as forest machines with three or more driving wheels. Attempts have been made to replace the mechanical drive line with a substantially entirely hydraulic drive line, where each drive wheel is driven by a separate hydraulic motor. However, these attempts have shown that such drivelines require an extremely complicated control system to replace the differential function of a conventional mechanical driveline, as the system risks being hit by pressure drop if a wheel loses its bracket (loses contact with the ground).

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Various types of electrically propelled vehicles have been proposed over the years, but extremely few have for commercial reasons achieved commercial success. Electric propulsion is something that has so far occurred almost exclusively in connection with small vehicles up to passenger car size. US3171505 shows a passenger car with separate electric drive of the car's drive wheels. JP 2002-010405 schematically shows an electric powertrain for a loading machine, truck or the like with conventional two-wheel steering, where the wheels are driven by a separate electric motor and the rotation speed of the wheels in a turning maneuver is controlled by a control unit. To avoid slimming for any of the different wheels, the controller correctly calculates the rotational speed of each wheel with respect to steering wheel stroke, speed and timing of steering wheel change. The control unit is therefore built around a very advanced algorithm.

Brief description of the invention

The present invention intends to solve the problems of vehicles according to the preamble to claims

1st According to the invention, the basic object of the device according to claim 1 is achieved.

An advantage of the present invention is that it provides in a very simple and robust manner a vehicle with constant multi-wheel drive without advanced steering systems.

Another advantage is that the vehicle exhibits simpler and more robust construction since the power transmission from the engine is via electric conductors instead of mechanical axle arrangements. This is particularly advantageous when the vehicle has more than two drive axles. The simple design with many identical motor arrangements also leads to: *; ': production costs are reduced.

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Another advantage is that turning the arrangement according to the invention enables a considerable reduction.

...· ^of vehicle weight.

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A further advantage is that the vehicle exhibits significantly better fuel economy compared to • ·· .30 conventional vehicles, which consequently results in reduced emissions.

Advantageous embodiments of the invention are set forth in the following dependent claims.

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Figure Description

Figures 1a, 1b and 1c show schematically different types of shaft arrangements according to the present invention.

Figures 2a and 2b show two more detailed embodiments of the present invention.

Figure 3 shows an embodiment of a drive shaft according to the present invention.

Detailed description of the invention

Throughout the following text, the term "vehicle side" is used with reference to the normal direction of travel of the vehicle, and the same applies to the terms right and left side respectively.

As mentioned above, JP 2002-010405 discloses an advanced system for controlling individual rotational frequencies of the wheels of a vehicle with individual drive of each wheel. However, the present invention is based on the realization that substantially the entire advanced steering system can be replaced by a direct-coupled steering system, consisting essentially of a steering angle sensor, if the vehicle is arranged so that its wheels on the right and left sides always follow the same wheel track when driven. In a turn maneuver, all wheels on the respective side of the vehicle move along the same circular arc at the same speed, and if the wheels have the same radius even with the same rotational speed. Throughout the following description ···: assume that all wheels have the same radius. By the term direct-coupled steering system is meant a system £ 5 which uses only the current steering angle for controlling the relative speed of the wheels on the right and right, respectively. left side.

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...^: The simplest example of a vehicle of this type is a symmetrical waist-driven vehicle, which is shown schematically in Figure 1 a. Such a vehicle has a symmetrically located axis of rotation, around which the two wheel pairs of the wheel axles are turned. Figure 1b shows an alternative form of symmetrical waist control comprising two separate rotary shafts, but where the rotations are about

526 The 740 axis is linked through a link arrangement (not shown) so that symmetry is achieved. Examples of symmetry compensating arrangements are shown in SE 500 259. Such arrangements are particularly applicable to vehicles with more than two wheel pairs, for example forest machines with 3 or more wheel pairs as shown schematically in Figure 1c.

As mentioned above and shown schematically in Figure 1a, the vehicle 10 of the present invention comprises a steering angle sensor 20 arranged to record the current steering angle of the vehicle 10 and two drive shafts 30, 31 with drive wheels 30H, 30V, 31H, 31V and associated driving arrangements 40H, 40V, 41H, 41V. Of course, the vehicle also includes control means for both direction and speed (not shown). The output of the speed controlled means together with the control angle sensor 20 determines the relative rotational frequency of the drive wheels 30H, 30V, 31H, 31V.

The steering angle sensor 20 is preferably arranged at the pivot axis of the vehicle 10, but it can also be arranged at the vehicle's steering means (eg steering wheel) or at some intermediate position. The control sensor 20 generates / modifies an analog control angle signal as shown in the embodiment shown in Figure 2a and described in detail below, or it provides a digital control angle signal. The sensor 20 can be designed in many different ways, such as a rotary resistor, linear sliding resistor, digital angle / position sensor, or the like.

In one embodiment, the sensor 20 is made up of two separate means, one for the right-hand turn and one for the left-hand turn, which are activated when pivoting in each direction. Due to this construction, the sensor 20 does not affect the rotational frequency of the "outer" wheels during a swing manover, while lowering the rotational frequency of the inner wheels. The degree to which the sensor 20 ·· ♦^:. · $ 2 affects the relative rotational frequency, of course, adapted to the current vehicle's • design, with regard to axle spacing, axle width, wheel diameter, steering design, etc. Of course, the system can also be designed so that constant speed is maintained through a ··· swing maneuver (provided that the speed control means is not changed) by increasing the ··· ··· rotation speed of the outer drive wheels while increasing the frequency of rotation of the internal *. 30 drive wheels are lowered.

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The drive arrangements 4OH, 40V, 41H, 41V are preferably designed as separate drive arrangements with individually controllable rotational frequency, where all drive arrangements on the same side are controlled by the same steering angle signal from the steering angle sensor 20. This solution means that the relative rotational frequency of all driving wheels on the respective driving direction of the vehicle , in accordance with the steering angle signal from the steering angle sensor. Each of these drive arrangements 40H, 40V, 41H, 41V preferably includes an electric drive motor, but alternative embodiments of hydraulic drive or the like may also be envisaged. A preferred embodiment of such a drive arrangement comprises an AC motor whose speed is determined by the frequency of the AC (synchronous motor). In such an embodiment, preferably, each drive arrangement 40H, 40V, 41H, 41V also includes a voltage converter capable of delivering AC at controllable frequency. Alternatively, one and the same voltage converter can be connected to two or more drive arrangements on the same side. Similarly, all drive arrangements on one side (right or left) can be mechanically coupled and driven by a common motor. According to another alternative embodiment, each drive wheel pair can be driven by the same engine arrangement with a gearbox with controllable ratio of relative rotational speeds for the right and left sides respectively.

In a preferred embodiment, the drive arrangements 40H, 40V, 41H, 41V include an electric drive motor which is supplied with electrical energy from a power source on the vehicle. This power source may be a battery arrangement or a current generating arrangement, such as a generator coupled to an internal combustion engine or fuel cell.

According to one embodiment, the output signals from the speed control means and the control angle sensor 20 are combined into a right and a right hand. a left signal which is fed to the driver arrangements on: right 40H, 41H respectively. left side 40V, 41V, whose rotation speed is set according to the respective signal. Alternatively, the drive arrangements 40H, 40V, 41H, 41V may be provided with • ··

Separate inputs for speed or. steering angle signal, whereby the general speed ··· ··· * is determined by the speed signal and the steering angle signal is interpreted as a deviation from the • ·. 3Ö general speed. This embodiment is particularly suitable when the signals are digital signals and each drive arrangement 40H, 40V, 41H, 41V includes a voltage converter which controls the rotational speed of the arrangement.

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Figure 2a shows a more detailed example of a driveline 100 for a vehicle according to the present invention. The drive line 100 is a so-called hybrid type and comprises a diesel engine 110 which drives a generator 120. The generator 120 is an alternator that generates via a rectifier a main supply 130 of direct current. The main supply 130 is represented by two powerful (flexible) conductors which, via branch lines, communicate with the individual drive arrangements 150 at the respective drive wheels 160, whereby these are supplied with direct current. A battery 140 is coupled to the main supply 130 to store excess energy and emit additional energy in load situations that require more energy than the generator 120 provides.

The individual drive arrangements 150 at each drive wheel 160 are all substantially identical and include a controllable voltage converter 170, an electric motor 180 and a gearbox 190. The controllable voltage converter 170 has a DC input 200 connected to the main supply 130 as above, a control signal input 210 coupled to a control system 240 and an alternating current output 220 connected to the electric motor 180. The voltage converter 170 is arranged to convert direct current from the main supply 130 to an alternating current at a frequency controlled by a control signal Vs, Hs received via the control signal input 210. Such controllable voltage converters 170 are well known in the art and require no further description.

The output alternating current is of a triple type and the motor 180 is consequently a three phase motor which rotates at a rotational speed determined by the frequency of the alternating current. An advantage of this arrangement is that the motor 180 rotates at substantially constant speed independent of load (higher load requires higher current).

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The engine 180 is in turn connected to the respective drive wheels via a mechanical gearbox arrangement 190 which converts the speed of the engine 180 in a suitable manner so that the vehicle can be driven within a suitable speed range.

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As previously described, the transmission line 100 control system 240 is very simple for the design, compared to known systems. In the present embodiment, the control system 240 comprises a ··· 'overall speed regulating means 250 in the form of a voltage divider which, on the input side, is supplied with a DC voltage of, for example, 5 volts and gives a signal between 0-5 ···

526 740 volts as output Ss, depending on the 250 position of the device. The control system 240 further includes steering angle sensors 260h, 260v for the vehicle's right and left. left side. These control angle sensors 260h, 260v also function as voltage dividers whose input side is supplied with the output signal Ss from the speed regulating means 250. The output signals Hs, Vs from the control angle sensors

260H and 260V are routed to the control signal inputs 210 of all motor arrangements 150 on each side. The steering angle sensors 260H, 260V are coupled to the vehicle's control in such a way that when the vehicle is driven straight ahead, the output signal Ss of the speed regulating means 250 passes unaffected by the steering angle sensors 260H, 260V, (Vs = Ss = Hs) and when the vehicle performs a pivot maneuver. Vs or Hs for the side to which the vehicle turns, while the control voltage Vs or Hs for the other side remains unchanged (Vs = Ss&gt; Hs for the right turn and Vs &lt;Ss = Hs for the left turn).

Accordingly, the input signals Hs, Vs to the voltage converters 170 are analog signals having a voltage between 0 and 5 volts and corresponding outputs to the electric motors 180 are controlled such that the speed varies from 0 to the maximum permissible speed by varying the frequency of the output drive current from 0 to maximum frequency. Through this arrangement, the outer wheels at cash Ss maintain the same speed during all turning maneuvers. For this to work satisfactorily, the two control angle sensors 260h, 260v are calibrated so that the lowering of rotational frequency induced by the output signals Vs, Hs corresponds to the shortened travel path of the wheels.

Figure 2b shows an alternate embodiment of drive line 100, where all electric motors 180 on each side Η, V are connected to one and the same voltage converter 170. This embodiment uses fewer voltage converters 170, but on the other hand it provides more wiring. Combinations of these two embodiments can also be envisaged, where drive shafts located close to each other utilize common voltage converters 170.

* • · ···. Figure 3 shows a disassembled view of a drive shaft 300 to be used in a vehicle according to the present ··· • · ·. invention. By creating a standard drive shaft, a simple and robust vehicle • ·· * * 3f) can be designed. Furthermore, such a vehicle becomes easy to repair, as the number of spare parts such as * * ': needed for repair is minimized. The drive shaft 300 comprises a shaft beam 310 having a ··· * · ': drive arrangement 320H, respectively. 320V detachable at each end. Both ···

526 The 740 drive arrangements 320H, V are identical in structure, and include an electric motor 330, a gear arrangement with wheel bearings 340 and a hub 350. Alternatively, the respective drive arrangements 320H, V may also include a voltage converter, which is then connected to the vehicle's main power supply and vehicle control system. The drive shaft 300 is then appropriately mounted on a vehicle and the motors 330 are electrically connected to a controllable electrical supply system in the vehicle. As mentioned above, this structure entails very simplified repair procedures, since the entire drive shaft 300 or individual drive arrangements 320H, V can easily be replaced if something has broken. Furthermore, it will be easier to both design and manufacture vehicles based on drive axles of this type.

The driveline of the present invention has been described for a wheeled vehicle, but it can of course be used to control the differential distribution of a tire vehicle or both wheel and tire vehicle such as a tire trolley or the like.

In experimental operations, it has been found that an electric propulsion vehicle according to the present invention exhibits unmatched fuel economy compared to similar vehicles with conventional powertrain. For a forest machine with more than two drive wheels, a 50 percent reduction in fuel consumption has been demonstrated in unloaded operation. In loaded operation, the lowering is expected to be even greater, since the drive arrangement of the present invention also allows the vehicle to be made easier. It is estimated that the weight of an attendant can be halved if constructed with such a driveline. In addition, the vehicle's energy consumption can be further reduced by the use of so-called. regenerative motor brake, where the braking energy is recovered via the electric motors which, when motor braking, act as generators and thus generate current that can be stored in the vehicle's battery.

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