The invention relates to a propulsion unit rotating shaft (also called a swinging arm motor unit) for single track or multiple track vehicles, driven by an electric motor, particularly for motor scooters and light vehicles for transporting persons or goods, etc., with a driving motor, which is disposed in the region of one end of an extended rotating shaft housing (also called a swinging transmission housing) and constructed as an electric motor with a largely closed housing, and a hub, which is mounted rotatably in the region of the other end of the rotating shaft housing and is intended to hold a driving wheel of the vehicle, the drive shaft of the driving motor, which is passed into the rotating shaft housing, being positively coupled with the wheel hub of the driving wheel of the vehicle by a transmission device, encapsulated in the housing for the rotating shaft and the rotating shaft housing having facilities for the pivotable mounting about an axis at a distance from the axis of rotation of the wheel hub and extending parallel to it at or in the frame or chassis of the motor-driven vehicle, and at least one overriding clutch being provided, which cancels the positive coupling between the driving motor and the driving wheel of the vehicle, when the driving moment, initiated by the driving motor in the transmission device, is smaller than a torque, acting from the driving wheel of the vehicle over the wheel hub on the transmission device.
Such propulsion unit rotating shafts, which represent an integral structural unit of a driving motor, a rotating shaft housing accommodating a transmission unit and a hub, which is intended for holding the driving wheel, is mounted in the rotating shaft housing and coupled over the transmission device with the driving mechanism of the driving motor, are used especially for two wheel vehicles of lower power, such as motor scooters, but also for three- and four-wheel vehicles, such as carts, golf carts, etc. Moreover, internal combustion engines are used almost exclusively at the present time as driving motors and, because of their particular torque characteristics, require gears in the transmission, which permit the step-up ratio between the motor drive and the driving wheel to be varied continuously or in several steps. Such infinitely variable or multistep gears necessarily have an appreciable weight and, depending on the construction and in comparison to the driving power generated by the driving motor decrease, due to transmission losses (friction, etc.), the driving power available at the driving wheel. Aside from the unfavorable performance or torque characteristics, the internal combustion engines also have further disadvantages, which lie, for example, in their complex construction, as well as in the emission of environmentally harmful exhaust gases and the generation of disturbing noise.
The use of electric motors as driving motors, which has been proposed already earlier for heavier passenger cars and for trucks, has in the past not been able to gain acceptance although, with respect to their available torque characteristics, electric motors were more advantageous than internal combustion engines. For the driving performance required, they were even able to bring about a small saving in weight which, however, was converted into an unfavorable ratio due to the weight and the space required by storage system (accumulators, batteries, etc.) for the electrical energy required for driving the motors. In comparison to vehicles driven by internal combustion engines, vehicles driven by electric motors were heavy and, as a result of the limited capacity of the electrical storage system, had only short, usable range. The service life of the electrical storage system was also unsatisfactory.
For electric motors, as well as for electric accumulators, recent developments have led to improvements, which have lessened previously existing disadvantages. For example, dc motors in the form of xe2x80x9caxial field motorsxe2x80x9d (WO 95/17779) have been developed which, because of their special construction, make available high driving moments already at a low rpm and, moreover, can be controlled over a larger range of rpm. In the sector of electric accumulators, the long-known lead accumulators, as well as the accumulators working with new electrode materials, have been developed further and have more advantageous values not only with respect to the weight to capacity ratio, but also with respect to the charging times required. The service life was also improved. Electric vehicles and especially motor scooters of the initially mentioned type (WO 97/18125 A2) have already been proposed, but have not yet led to marketable products.
It is an object of the invention to provide a propulsion unit rotating shaft for special low performance, motor-driven vehicles, for which the advantages of the electrical driving mechanism come to the fore and the previously existing disadvantages are clearly reduced.
Starting out from a propulsion unit rotating shaft of the initially mentioned type, this objective is accomplished pursuant to the invention owing to the fact that the transmission device has at least two transmission trains, which are connected in series, and that the or one of the free-running hubs is connected between the two transmission trains. This arrangement of the free-running hubs between two transmission trains connected in series has advantages with respect to the accessibility of the free-running hub and, with that, to its maintenance, as well as with respect to the load placed upon it due to the decrease in the rpm of the revolving part of the free-running hub, which continues to be coupled with the driving wheel in pushing operation, in comparison with the free-running hub disposed on the motor side.
A further overriding clutch may also be disposed in the driving motor itself, before the latter is connected with the transmission device, for example, between the rotor hub and the driven shaft. This free-running hub coupling is then an integral part of the driving motor.
In a further advantageous development of the invention, several overriding clutches may be provided, of which one may be provided in the coupling region between the driving motor or, as previously mentioned, in the driving motor and the transmission and the other in the region between the transmission device and the wheel hub.
It is advisable to dispose the electric motor at the rotating shaft housing with the axis of rotation parallel to the wheel hub for the driving wheel of the vehicle. In this case, the device for the pivotable mounting of the rotating shaft housing in or at the frame or chassis of the associated vehicle is constructed, so that the axis of rotation of the driving motor and the pivoting axis of the propulsion unit rotating shaft essentially coincide or have only a slight distance from one another. During the horizontal sweep of the propulsion unit rotating shaft which, because it is supported at the chassis or frame over a spring or a shock-absorbing leg, at the same time assumes the function of the suspension of the driving wheel of the vehicle, the driving motor only carries out a horizontal sweep motion, that is, it does not change its height position. As a result, the effect of the weight of the driving motor on the spring action is minimized.
The driving motor of the inventive propulsion unit rotating shaft preferably is constructed as a so-called axial field motor, which has the previously described advantageous properties with respect to the advantageous course of the torque and with respect to the range of the rpm, which can be controlled. The use of electric motors of other constructions also comes into consideration.
As a result, it is possible to construct the transmission device without interposing step-down gears or step-up gears as a simple non-positive or positive transmission train, such as a belt drive or a chain drive, as a result of which there are no transmission losses due to step-down steps or gear steps.
The housing of the electric motor advantageously is constructed largely closed, an inlet and an outlet being provided, so that cooling air can flow through. At least the inlet advisably is preceded by a filter for the cooling air, in order to prevent penetration of and contamination by dust particles, especially also penetration of metallic particles into the motor.
The inlet for the cooling air and the filter device provided there are advantageously disposed in vehicles with the inventive propulsion unit rotating shaft as high as possible, in order, to filter out contaminating particles and to exclude access of water as well, when driving through water or heavy thunder showers. This arrangement is of advantage also with respect to the inlet temperature of the cooling air since, in unfavorable cases, the air temperature directly over the asphalt street surfaces, strongly heated by radiation from the sun, can lie appreciably above the actual ambient temperature. When the propulsion unit rotating shaft is used in single track vehicles, such as motor scooters, the space immediately below the bench seat is available for this purpose.
The free-running hub itself can be constructed as a known clamp or sleeve-type overriding clutch which, while being small in size and having a corresponding low weight, functions reliably and has a reliable service life.
If propulsion unit rotating shafts, constructed in the inventive manner, are to be used as driving units for multitrack vehicles, such as carts, motorized rickshaws, golf carts, etc., for which a motorized reverse driving mechanism is desirable or necessary, devices for optionally blocking the free-running hub function of the free-running hub or hubs are advantageously provided. This embodiment permits a reverse driving mechanism after blockage of the free-running hub function by switching over the connecting of the electrical motor. A separate mechanical gear step as a reversing gear is then not required.
When the inventive propulsion unit rotating shaft is used as a driving mechanism for a motor scooter with a metal profile frame, which carries the steering head for the front wheel suspension at the front end and for which the frame has two metal profiles, which are at a distance from one another transversely to the driving direction of the scooter and constructed as closed tubular profiles, which are brought together in the region of the steering head and fastened, are taken from the steering head in each case diagonally towards the outside and in the downwards direction as far as below the level of the footrest platform of the scooter, then in a parallel distance from one another approximately horizontal into the region of what is the rear end of the footrest platform in the driving direction and from there once again in the upwards direction as far as approximately the level of the seat or the bench seat of the scooter and, between the drawtubes of metal profiles, spaced apart in the driving direction, seats are provided for the electrical storage system or systems, the embodiment advisably is such that, at least the seats for the current storage systems, provided in the region of the parallel, horizontal metal profile sections, which are at a distance from one another, have a tub, which is fastened to the metal profile sections and not only shields the electrical storage system against wetness, becoming dirty or stone impact from the street side, but additionally contributes to stiffening the frame.
The metal profiles advisably are constructed as a rectangular or a flat, half-round tubular profile of steel or light metal.