GB2254965A

GB2254965A - Improvements in transmission systems for electrically propelled vehicles

Info

Publication number: GB2254965A
Application number: GB9106012A
Authority: GB
Inventors: Shi-Hai Chien
Original assignee: LIAO PETER BOR SHYANG
Current assignee: LIAO PETER BOR SHYANG
Priority date: 1991-03-06
Filing date: 1991-03-21
Publication date: 1992-10-21
Anticipated expiration: 2011-03-21
Also published as: GB9106012D0; FR2674484B1; DE4108386A1; DE4108386C2; FR2674484A1; GB2254965B

Description

) 2 ' -) 49,15 1 _ IMPROVEMENTS IN TRANSMISSION SYSTEMS The present

invention relates to improvements in transmission systems and in particular to a gear shift system mainly adapted for an electrically operated automobile such as a remote control electrical automobile. The manually operated gear shift system can effect 3-stage speed variation.

Remote control electrical automobiles have been developed over the past years to a satisfactory level as a result of the improvement in radio technology. However, the mechanical transmission adopted in the field has still not been developed to cope with the promotion in radio technology. The conventional electrical automobile employs a D-C electrical motor and a simple transmission system which is comprised of a simplified differential device. By changing the gear ratio of the transmission device, a proper torsion can be selected to meet the power requirements.

However, the general type of remote control electrical automobile is not equipped with an effective enough gear shift system which will permit the controlled automobile to run more in response to the driving condition.

A primary object of the present invention is to provide an improved transmission system comprising a manual gear shift system mainly adapted for electrically operated automobile, wherein a specially designed motor, which has a rotatable stator made up of the shell thereof and a rotor, is employed. The rotatable shell-stator is relatively movable against the rotor and the motor serves as a power source of the automobile. A pair of differential gear devices made up of gears having different gear ratios are employed to control the operation of the wheels. By way of selectively locking the transmission shafts of the automobile, the speed of the wheels can be accordingly varied.

According to the invention there is provided a transmission system for an electrically operated vehicle comprising an electric motor having a stator and a rotor which are rotable in contrary directions and output shafts from the stator and the rotor, a braking member associated with each output shaft and a braking selector which can be selectively operated to lock one or other of the output shafts leaving the other free to rotate.

To better illustrate the structural features and operational modes of the present invention, a preferred embodiment will now be described with reference to the accompanying drawings, in which:- Fig. 1 is a perspective view of a conventional transmission device; Fig. 2 is a perspective sectional view of the relative rotation motor for the gear shift system of the present invention with parts ommitted for clarity; Fig. 3 is a perspective view of the 3-stage gear shift transmission device; Fig. 4 is a plan view of the transmission device of Fig. 3; Fig. 5 is a diagram showing the centrifugal clutch of the present invention; and Fig. 6 is a diagram showing a box spanner type ratchet gear means which can be selectively operated.

Referring to Fig. 1, a conventional differential gear set is related to the engine by way of a universal joint D1 and a rotation shaft D2. To the end of the rotation shaft D2 is attached a helical gear D3 which is engaged with the annular gear D4 of the differential gear set. A pair of planet gears is engaged with the rotating annular gear D4 so that the engine power can be output to left and right drive shafts D61 and D62 respectively. As is well known, when one of the drive shafts D61 or D62 is locked so that it cannot rotate, the other left drive shaft D62 or D61 will take all the power from the engine.

As shown in Fig. 2, a specially designed electric motor 1, which is called herein a relative-rotation motor, is employed as the power source of the electrical automobile of the present invention. This special motor is structured to have a rotatable outer shell serving as the stator 11 of the motor and a core rotor 12, that are in opposite rotation when the electrical motor is in operation. Thereby the power produced by the relative rotation electric motor 1 can be output in both directions.

To permit the outer shell stator 11 to rotate freely, the electrical power source is introduced into the electric motor by way of a pair of copper rings 141, 142 disposed on the outer shell thereof. The electrical power of the battery can be input by a couple of corresponding carbon brushes 13 into the motor 1 so that the outer shell stator 11 can be rotated without interference. At each end of the outer shell stator 11 is disposed a bearing 15 to support the core rotor 12 whilst permitting the same to smoothly rotate. The 35 outward extended shaft 121 of the core rotor 12 is identical to a conventional electric motor 1 and serves as a power output terminal. Another power output shaft 111 is integrally disposed at the other end of the outer shell stator 11, extended therefrom and supported by a bearing 16 serving as the second power output terminal. As to the internal magnetic poles and wiring of the electric motor, they are the same as in known motors. The electric motor is designed such that the rotational inertia of the outer shell stator 11 and the core rotor 12 are 10 identical. Thus, the output terminals of the electrical motor 1, i.e. the outer shell stator 11 and the core rotor 12, can each output half of the output power. The output terminal 111 of the stator 11 can be 15 locked so as not to rotate, and in this state all of the power of the electric motor 1 is directed to the shaft 121 of the core rotor 12. Similarly shaft 121 can be locked, such that all of the power of the motor 1 is directed to output shaft ill of the shell 20 stator 11. It can thus be seen that the specially designed relative rotation electric motor can have the same function as a differential gear device to balance the power transmission. To clarify the operation modes of the system of 25 the present invention, a 3-stage speed variation process is given as below. Referring to Figs. 3 and 4, the relative rotation electric motor 1 serves as the power source, and comprises, as above, the outer shell stator 11 30 and the core rotor 12. The power generated by the electric motor 1 is transmitted by way of front and rear flanged members 51, 52 and the centrifugal clutches 41, 42 (shown in Fig. 3) to the transmission shafts 21, 22 and finally to the front and rear 35 differential gear devices 1D, 2D. Furthermore, four rotation shafts 31, 32, 33 and 34 are employed to convey the power produced by the motor to the respective wheels 81, 82, 83, 84.

A control stick 7 with a C-shaped prong 71 at the end thereof is pivotable at a pivot joint 72, the movement of which is as shown by the dotted line in Fig. 4. The prong 71 has a pair of arms 711, 712.

When the control stick 7 is in a neutral position, the two arms 711, 712 are held away from the surfaces of the flanged members 51, 52 so that the power produced by the electric motor's outer shell stator 11 and the core rotor 12 can be output.

Once the control stick 7 is pivoted to a position with the arm 711 in contact with the front flanged member 51, the outer shell stator 11 will be locked so that it does not rotate. Thus the power produced by the electrical motor 1 is output entirely from the core rotor 12. In the same manner, when the control stick 7 is moved to a position with the arm 712 in contact with the rear flanged member 52, the power produced by the electric motor 1 will be output entirely from the outer shell stator 11. The centrifugal clutches 41, 42 permit the transmission shafts 21, 22 to freely rotate even when the front and rear flanged members 51, 52 are locked so that no braking condition will exist.

It is known from the above description that there are 3 different kinds of speed condition produced by the aforementioned transmission system.

If the front differential gear device 1D has an annular gear D4, which is engaged with a helical gear D3 disposed at the end of the transmission shaft 21, with a gear ratio therebetween 3:1 (refer to Fig. 1); and if the gear ratio between the annular gear D4 of the rear differential gear device 2D and the helical gear D3 attached at the end of the transmission shaft 22 is 3:2; when the rotation speed of the relative rotation electric motor 1 has a speed of 9000 rpm, the following conditions can be produced:- 1. When the transmission shafts 21, 22 are free to rotate, the core rotor 12 drives the transmission shaft 21 at a speed of 6000 rpm. The speed of the rotation shafts of the front wheels is 6000 X 1/3 2000 rpm. Moreover, the outer shell stator 11 drives the transmission shaft 22 at a speed of 3000 rpm and the rotation shafts of the rear wheels at 3000 X 2/3 = 2000 rpm. With the four wheels operating at the same speed, the automobile moves smoothly over an even surface.

2. When the transmission shaft 22 associated with the outer shell stator of the electric motor is locked, the 9000 rpm speed produced by the electric motor will be output by way of the core rotor to the transmission shaft 21, and the speed of the rotation shafts of the front wheels will be increased to 9000 X 1/3 = 3000 rpm (wheel speed). The automobile is therefore driven faster.

3. When the transmission shaft 22 associated with the outer shell stator is released to rotate and the transmission shaft 21 coupled to the core rotor is locked, the electric motor will drive the transmission shaft 22 at a speed of 9000 rpm, and the rotation shafts of the rear wheels will reach a speed of 9000 X 2/3 = 6000 rpm. Thus the vehicle is driven even faster.

In the case that one of the transmission shafts 21, 22 is locked so as not to rotate, the front or rear wheels can still be driven to rotate along with the wheels associated with the free transmission shaft due to the use of the centrifugal clutches.

The above theory of how the speed of the wheels is varied can be applied in the following manner.

In the first instance given in the previous application, it can be considered that the automobile is put into "first gear" which can provide a larger torsional force to make the stationary wheels move.

In the second application, the automobile is considered to be in "second gear", and only the front wheels are driven. The vehicle is more easily controlled in turning corners and the speed can easily be increased. The automobile in this condition is suitable for a curved road.

In the third application, the vehicle is considered to be in "third gear" and only the rear wheels are driven. Under this condition, the automobile is suitable for accelerating on a straight is road. When the vehicle is on the move,' not much torsion is needed and the "third gear" is capable of giving a high speed output.

In another embodiment of the invention the centrifugal clutch can be replaced by ratchet gear means which can provide the same function as the centrifugal clutch. However, the ratchet gear will prevent the power generated by the electric motor from being transmitted to the wheels when the motor is rotating in a reverse direction to drive the vehicle in reverse. In this condition the electric motor is unable to produce any output at all. To overcome the problem, a box spanner type ratchet gear means, which has a neutral position and a clockwise and counter-clockwise position, is used so to permit the ratchet gear means to be set in 3 options. The ratchet is limited to spin in only a clockwise or a counter-clockwise direction or to rotate without restraint at all. The box spanner type gear means can be designed according to the common box spanner as shown in Fig. 6.

8 -,

Claims

CLAIMS:

1. A transmission system for an electrically operated vehicle comprising an electric motor having a stator and a rotor which are rotable in contrary directions and output shafts from the stator and the rotor, a braking member associated with each output shaft and a braking selector which can be selectively operated to lock one or other of the output shafts leaving the other free to rotate.

2. A transmission system as claimed in claim 1 further comprising a transmission shaft connected to each output shaft via clutch means, in which said clutch means are operable to allow the transmission shaft to freely rotate when the output shaft associated therewith is locked.

3. A transmission system as claimed in claim 2 further comprising differential means connected to each of the transmission shafts having different gear ratios.

4. A transmission system as claimed in any one of the preceding claims in which the braking member comprises a flanged member mounted on the output shafts, and the braking selector has a pair of arms and is pivotable such that each of the arms can be moved into and out of braking contact with one of the flanged members.

5. A transmission system as claimed in any one of the preceding claims in which the electric motor comprises an outer shell stator integral with one of said output shafts and a core rotor disposed inside said shell.

- 9

6. A transmission system as claimed in any one of the preceding claims in which the shafts of the motor are supported by bearings to enable the stator and rotor to rotate freely.

7. A speed transmission system as claimed in any one of the preceding claims in which the clutch means comprises a centrifugal clutch.

8. A transmission system as claimed in any one of the preceding claims in which the clutch means comprise ratchet gear means having three positions such that the ratchet gear can be rotated clockwise or anticlockwise or without restraint.

is

9. A transmission system for an electrically operated vehicle comprising a relative-rotation electric motor having a pair of output shafts, a front flanged member in association with one of said output shafts of said electric motor, a rear flanged member in association with the other said output shaft of said electric motor, a pair of centrifugal clutches disposed in juxtaposition to said front flanged members and said rear flanged member respectively, pair of transmission shafts disposed in association with said centrifugal clutches at one end respectively, a pair of front and rear differential gear devices connected to the other end of said corresponding transmission shafts respectively, a control stick having a C-shaped prong with a pair of hands which can be selectively in contact with said round front flanged member or said rear flanged member so as to lock one of said round flanged members not to rotate when said control stick is pivoted to either side from a neutral position of said control stick, by means of said control stick which can be in selective contact with one of said front and rear flanged members so to lock one of said output shafts not to rotate.

10. A speed variable transmission system for electrically operated vehicle as defined in claim 9 wherein said relative-rotation electric motor mainly comprises an outer shell stator which is equipped with an extended output shaft integrally associated with said shell of said motor, said extended output shaft being rotatably supported by a bearing means so that said outer shell stator can be rotated freely, a core rotor disposed inside said shell stator and rotatably supported by a bearing means located respectively at each end of said shell, said core rotor having an outward extended shaft as a common electrical motor, on the outer surface of said outer shell stator being disposed a pair of copper rings which are in constant contact with a pair of carbon brushes so to permit the electrical energy from a battery to deliver to said relative rotation electric motor, said relative rotation electric motor being characterised in that said outer shell stator is able to rotate in opposite direction with said core rotor so that energy can be output by way of a pair of said output shafts.

11. A speed variable transmission system as defined in claim 9 or claim 10 wherein said centrifugal clutches can be replaced by a pair of box spanner type ratchet gear means which can be put in 3 options so that the ratchet gear can be rotated only in clockwise or counter-clockwise direction or without restraint.

12. A transmission system as hereinbefore described with reference to and as shown in Fig. 2 to 6 of the accompanying drawings.