Motor vehicles – Ski- or skate-type vehicle for imparting movement to a...
Reexamination Certificate
1998-04-14
2001-02-06
DePumpo, Daniel G. (Department: 3611)
Motor vehicles
Ski- or skate-type vehicle for imparting movement to a...
C180S181000, C180S267000, C280S087042
Reexamination Certificate
active
06182779
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a power transmission device which transmits the driving force of a power generator (engine), such as an internal combustion engine and an electric motor, to right and left drive wheels, and relates to a transportation device employing this power transmission device.
2. Description of the Related Art
In a skateboard, a rider can stand on it and can run in a desired direction by putting his or her feet on the board supported by rollers and keeping his or her balance.
Simple transportation devices are being developed and they are utilized as personal transportation means, sport apparatus and leisure equipment. For example, a skateboard with a power generator such as an engine under development is able to run itself easily even on a flat surface. Such devices are still further being developed for improving the turning performance so as to rendering the device easy to control and providing the devices with enough driving capability to qualify as sport apparatus or leisure equipment. Also, some devices are being developed for improving the driving performance so that the devices may run on a rough wasteland as well as on a flat plane.
A differential gear is a common power transmitting device to transmit a driving force generated by an engine to right and left drive wheels and that can absorb the difference in rotation speed of these drive wheels at a turning due to the difference in the number of revolutions between inside and outside wheels. In a transportation device like the skateboard with an engine as described above, if the rider shifts its weight to turn, one of the drive wheels parts from the ground and runs idle. Therefore, if the differential gear is applied in such transportation device, it is impossible to obtain a stable driving force. Also, on a wasteland, one of the drive wheels likely leaves the ground or slips, thus it is impossible to obtain the desired driving force by the differential gear. It is desirable that stable driving capacity be obtained under a variety of conditions such as running on a rough place to enjoy sports, leisure, and the like. In addition, it is important for the user to be able to control the direction easily.
Although it is possible to attach a differential-limiting device to deal with the above problems, the power transmission device becomes large and expensive, which causes the transportation device to be heavy and expensive.
Therefore, an object of this invention is to provide a simple power transmission device having a function of absorbing the difference in the number of revolutions between the inside and outside wheels, and a function transmitting the driving force to the right and left wheels more continuously so as to transmit the stable driving force even when the transportation device inclines while running in a wasteland or curving. Another object of this invention is to provide a power transmission device appropriate for the aforementioned transportation device, which is lightweight, can be provided at a low cost, and has an excellent power transmission property, and to provide a transportation device which, by employing this power transmission device, has high steering performance and driving performance, and which can run in a rough place or a wasteland.
SUMMARY OF THE INVENTION
In this invention, the driving force generated by the power generator is transmitted to the right and left drive wheels through at least two separate one-way clutches. Therefore the right and left drive wheels are driven by a power transmitted via a separate one-way clutch respectively. That is, the power transmission device according to this invention has at least two one-way clutches that can each transmit the driving force generated by the power generator to the right and left drive wheels. Because the power is transmitted to the drive wheels through the one-way clutches, it is possible to transmit the driving force of the front direction to the drive wheels without slip by setting the direction of the one-way clutches. Accordingly, if the condition of ground contact and the like of the right and left drive wheels are the same, it is possible to transmit the driving force of the power generator to each of the drive wheels almost half and half.
When the user turns the transportation device having these drive wheels, or when the transportation device runs on a rough road, the right and left drive wheels rotate at a different speed each other. In this case, by the power transmission device of this invention, the driving force is mainly transmitted to the drive wheel that rotates more slowly than the other through the one-way clutch. That is, the drive wheel which comes outside during the curves, the drive wheel which parts from the ground, and the drive wheel which contact load is decreased, becomes free from driving force. This is because the free traveling side of the one-way clutch connected to the above mentioned drive wheel can rotate faster than the driving side of the one way clutch connected to the power generator and the driving side of the other one way clutch. Accordingly, hardly any driving force is transmitted to the drive wheel rotating relatively faster, while most of the driving force is supplied to the other drive wheel rotating more slowly. Therefore by employing the power transmission device according to this invention, it is possible to supply the power to the drive wheels without fail while the inside and outside wheel rotating at a different speed when the transportation device curves. Thus it is possible to obtain the stable and/or continuous driving force in whichever direction the user turns the transportation device without lowering the turning (steering) performance of the transportation device.
In addition, in the power transmission device according to this invention, most of the power is transmitted to the drive wheel which rotates slowly. When the ground contacting worsens and one of the drive wheels parts from the ground and becomes run idle, the power is mostly transmitted to the other drive wheel which touches on the ground. Thus it is possible to obtain the stable and/or continuous driving force even if the wheel contact load of one of the drive wheels is small. And since the drive power dose not transmitted to the wheel with small contact load, such a wheel does not rotate at a over speed and also the engine dose not run over with no load.
As is clear from the above description, the power transmission device according to this invention has an excellent property that can automatically adjust the power supply to the drive wheels depending on the ground contacting of the drive wheels. Furthermore, it is possible to realize this excellent property of this power transmission device by a simple arrangement having a plurality of one-way clutches which transmit the power to the right and left drive wheels respectively. As a result, this power transmission device can be configured small and lightweight, and can be provided at a low cost. And because this power transmission device has a simple configuration, it becomes a highly reliable as a mechanism.
If the power transmission device according to this invention is employed, the drive wheels on both sides are joined to the power generator such as a gasoline engine or a motor through the one-way clutches. When the transportation device having this power transmission device runs down a slope or is drawn, the drive wheels become independent of the power generator and become free owing to the one-way clutches. Thus it is possible to run the transportation device depending on the running conditions independently of the power generator.
It is preferable that a transportation device such as a vehicle that employs the power transmission device has a brake device that controls the speed of the running vehicle. But if each wheel is provided with a brake, the structure of the surroundings of the wheels becomes complicated, the transportation device becomes heavy, and the cost of manufacturing increases. In th
Burns Doane Swecker & Mathis L.L.P.
DePumpo Daniel G.
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