Power-augmenting transmission structure for an electric car

A power-augmenting gear structure for an electric car includes a low-speed and power-augmenting transmitting route additionally installed in a gear case, with an output shaft of an electric motor extending in the gear case. The gear case has transmission gears forming conventional normal speed transmitting routes with normal speed reducing ratio for running on common flat roads, and a low-speed and power-augmenting transmitting route to be used in case of moving up an upward slope or coping with a condition needing a large torque. Then the electric motor may be reduced in its size, weight and cost, without necessity of enlarging it to have a large power.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a low-speed and power-augmenting transmission structure for an electric car, particularly to one provided in a gear case for augmenting the power of an electric car so as to move up an upward slope easily without increasing the power of the electric motor of an electric car.

2. Description of the Prior Arts

Nowadays numerous industries in our society depend upon fossil oil, and especially transportation requires tremendously large quantity of gasoline and diesel refined from fossil oil. As consumption of fossil oil has gone up and up, the price of fossil oil has risen up to a surprising level, so related sectors have been struggling to find substitutes all over the world. Therefore electricity has become one of its substitutes, used in electric cars or hybrids, in order to reduce heavy dependence on fossil oil. A conventional electric car shown inFIG. 1is mainly provided with a driving axle80, which drives a last gear70, and the last gear70then drives a rear wheel axle81to move the car forward or backward. However, a conventional electric car needs a very great power in case it runs up an upward slope, and manufacturers have to make the car and the electric motor larger to conquer this problem, and accordingly have to add up its cost and enlarge its body, in addition to the drawback that the rear wheel axle81becomes heavier to result in bad effect in its suspension.

SUMMARY OF THE INVENTION

This invention has an object to offer a low-speed power-augmenting transmission structure for an electric car, without changing the power of the electric motor so that the electric car can move up an upward slope easily or cope with a condition requiring a large torque.

The characteristic of the invention is a low-speed and power-augmenting transmission structure added to conventional general transmission gears provided in a gear case, so that an electric car may move up easily an upward slope or cope with a condition needing a large torque, belittling the largest power of an electric motor and accordingly reducing the size, weight and cost of the electric motor and its controller.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred embodiment of a power-augmenting transmission structure for an electric car in the present invention, as shown inFIGS. 2-5, includes an electric motor10, an output shaft100of the motor10, several transmission gears installed in a gear case20, and an output shaft200of the gear case20for rotate a last gear70, which drives a wheel axle (a rear wheel axle or a front wheel axle).

The gear case20has a general common speed transmission route20awith a normal speed reducing ratio for running on common flat roads, and a low-speed and power-augmenting transmission route20bwith a large speed-reducing ratio for moving up easily an upward slope or coping with a condition demanding a large torque.

The gear transmission system, referring toFIGS. 5-11, includes an output shaft100of the motor10, a first transmission gear120fixed on an end of the output shaft100, a second transmission gear121fixed on a first rotatable shaft30, a third transmission gear122fixed on a second rotatable shaft40, with the first gear120able to engage with the second gear121or the third gear122optionally by means of a clutch. The second and the third gear121and122have the same number of teeth. The gear transmission system further includes a fourth transmission gear123and a fifth transmission gear124fixed orderly on the first rotatable shaft30with the first gear121fixed thereon and having less teeth than the first gear121. The fourth and the fifth gear123and24may rotate synchronously with the first gear121, as shown inFIGS. 7 and 8.

Furthermore, the gear transmission system has a second rotatable shaft40, which is provided with a clutch13, and a sixth transmission gear125, a seventh transmission gear126and an eighth transmission gear127fixed orderly on the second rotatable shaft40that the third gear122is fixed on. Then the fourth gear123engages with or disengages from the sixth gear125by means of the clutch13as shown inFIGS. 6and7. The gear transmission system further includes a third rotatable shaft50in parallel to the first and the second rotatable shaft30and40, with a ninth transmission gear128engaging with the seventh gear126fixed thereon, and a fourth rotatable shaft60fixed with a guide gear130installed between the fifth gear124and the eighth gear127and engaging with the both gears124and127at the same time. Thus, the fifth gear124may reverse the rotating direction of the eighth gear127.

Moving forward and backward of an electric car is handled by a gear lever83and a clutch by a driver, as shown inFIG. 4, but this is a conventional method, its description is omitted there.

Then the flowing operation of the gear transmission system of the electric motor10is described now. In case of getting into the forward running mode, the motor10runs at the general common speed transmission route20aas shown inFIG. 12, its transmitting order starts from the output shaft100to the first gear120, then to the third gear122(on the second rotatable shaft40), then to the seventh gear126, then to the ninth gear128. More precisely, the motor10moves the first gear120, which then rotates the third gear122and the second rotatable shaft40at the same time, and then the second shaft40rotates the sixth gear125and the seventh gear126, so the seventh gear126rotates the ninth gear128. Finally the ninth gear128drives the driving axle to move the car forward.

In case of moving back the car, the gear leaver is handled to change to the moving back transmission route. Then the third gear122is disengaged from the first gear120by means of the clutch, and the transmission system of the motor10operates at the general common transmitting speed route20aas shown inFIG. 13, so the transmitting order starts from the output shaft100to the first gear120, then to the second gear121and the first rotatable shaft30at the same time, then to the fourth gear123, then to the sixth gear125and the second rotatable shaft40at the same time, then to the seventh gear126, and then to the ninth gear128. More minutely, the motor10rotates the first gear120, which then rotates the second gear121, so the first rotatable shaft30is rotated to move the fourth gear123, which then rotates the sixth gear125, so the sixth gear125rotates the second rotatable shaft40, which then rotates the seventh gear126to move the ninth gear128, so finally the car is driven to move back.

Next, when an electric car is to move up an upward slope or to have the power increased, the transmission gear system is set at the low-speed and power-augmenting transmitting route20bas shown inFIG. 14, then the operation order begins from the output shaft100to the first gear120, then to the second gear121, then to the first rotatable shaft30, then to the fifth gear124, then to the guide gear130, then to the eighth gear127, then to the second rotatable shaft40, then to the guide gear130to align the rotating direction of the fifth gear124to that of the eighth gear127, so that the second rotatable shaft40rotates the seventh gear126, which then rotates the ninth gear128. In this way, the electric car does not need to enlarge the power of the electric motor10, by means of the design of the speed reducing ratio of the first rotatable shaft30and all the transmission gears in addition to the rotating-direction reversing method effected by the guide gear130and the fifth gear124and the eighth gear127.

Moreover, if the electric car is needed to have a four wheel driving function, it is only required to install a front wheel driving gear131that is made to engage with the ninth gear128as shown inFIGS. 8-11, driving the front wheel axle82in conjunction of the rear wheel driving function, as shown inFIG. 15.

In this invention, by adding the low-speed and power-augmenting transmitting route20bto the general common speed gear route20ahaving a normal speed reducing ratio for running on common flat roads, the electric motor does not need to be enlarged and can have a large torque to move up easily an upward slope or to cope with a condition needing a large output power, reducing the size, the weight or the cost of the car.