JPS5924601B2 - Electric car speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a speed control device for controlling the running speed of an electric vehicle.

Generally, electric vehicles control running speed by changing the rotational speed of the motor depending on how much the accelerator is pressed, and direction is controlled by bundle operation.

FIG. 1 shows a schematic configuration of a speed control device for a battery forklift.

Battery B supplies DC power to the DC motor DM,
The average voltage is transferred to the chopper C that forms the main circuit of the speed control device.
It is controlled by the on/off ratio (conductivity) of H.

The on/off ratio of the chopper is determined by obtaining a timing signal controlled by a chopper control circuit LU which receives the output voltage of a potentiometer POTA linked to the accelerator.

In addition, AC□ is a contact point that enables the chopper control circuit LU to operate when the accelerator pedal starts to be depressed, M T 1 e M
T2 is a contactor 1 that switches the current polarity of the field winding F of the motor DM to switch forward/backward movement of the vehicle, and MS is a contactor that directly drives the motor DM in place of the chopper CH.

With such a speed control device, the on/off ratio of the chopper CH is changed according to the amount of accelerator pedal depression, and the motor D
The rotational speed of M and thus the running speed of the electric vehicle are controlled.

Therefore, in conventional speed control, the speed of the electric vehicle when turning is controlled only by the amount of depression of the accelerator, so if the speed when turning is too high, there is a risk of the vehicle rolling over.

An object of the present invention is to provide a speed control device that can automatically regulate the turning speed of an electric vehicle to an appropriate value and prevent accidents such as rollover.

Examples of the present invention will be described in detail below.

In FIG. 2, the AC speed generator G is directly connected to the shaft of the motor DM or to a portion that can detect the speed of the vehicle.

The diode bridge Ref and the capacitor C rectify and smooth the output current of the speed generator G, and provide the capacitor C with a DC voltage vN corresponding to the speed of the electric vehicle.

Note that in order to obtain the DC voltage vN, the AC speed generator G is not limited to the AC speed generator G, and may be replaced by a DC generator or a speed detector using an electronic frequency or pulse method.

Next, the detected DC voltage vN is input to the potentiometer po'rs, and a divided voltage of vN is obtained as the output voltage Vo.

This potentiometer POTs is used to set the maximum speed that is restricted to the electric vehicle when the turning radius of the vehicle is operated to be below a set value, and is used to adjust the gain of feedback control.

The switch SW forms a part of a turning radius detector that detects that the turning radius of the electric vehicle has been operated below a set value, and its closing operation changes the output voltage Vo of the potentiometer POTs to the output voltage Vo in the chopper control circuit LU. Introduced into the selection circuit.

The turning radius of an electric vehicle can be detected by a combination of a disc cam CM and a microswitch MSW shown in FIG.

That is, the symmetrical disc cam CM is rotated to the left or right depending on the operating angle of the handle, and when it is rotated to the left or right by an angle θL or θR corresponding to the set turning radius, the cam is activated. By pushing up the lever of the microswitch MSW and closing its contact SW, it is detected that the turning radius of the electric vehicle has been operated to be below a set value.

Next, the selection circuit SC in the chopper control circuit LU selects a potentiometer po'r provided through the switch SW.
The output voltage Vo of s and the potentiometer P shown in FIG.
The output voltage of oTA is connected to a reverse current blocking diode Ds,
It is introduced through the DA and serves as a common base input for the transistor Tr1 constituting the emitter follower amplifier circuit.

As a result, the higher one of the output voltages of the potentiometers POTs and POTA is selected and output as the output voltage VS of the transistor Tr1.

Note that the output voltage of the potentiometer POTA decreases as the accelerator pedal is depressed.

The timing signal generator osc controls the on/off ratio of the chopper CH according to the level of the output voltage VS of the selection circuit SC. .

With the speed control device configured in this manner, when the steering angle of the electric vehicle is near the tactile angle (straight ahead), the control of the microswitch MSW by the cam CM is between the contacts, and the switch S
Since W is in an open state, the output voltage V of the selection circuit SC
S corresponds to the output voltage of the potentiometer POTA corresponding to the amount of depression of the accelerator.

Therefore, if the load is constant, the speed of the vehicle corresponds to the amount of depression of the accelerator.

Next, when the steering wheel is operated to turn the vehicle and the operating angle becomes θR or 05 or more on the cam CM, the switch SW is closed and the selection circuit SC is supplied with a voltage corresponding to the vehicle speed and an accelerator pedal. A voltage corresponding to the amount of depression is introduced.

And if the output voltage of the potentiometer POTA is higher than the output voltage of the potentiometer POTs, e.g.
When the accelerator is operated so that the amount of accelerator depression is smaller than the vehicle speed at that time, a selection circuit SC selects the output voltage of the potentiometer POTA and controls the vehicle speed to decrease to a speed corresponding to the amount of accelerator depression.

Conversely, if the output voltage of POTA is lower than the output voltage of POTs, for example if the accelerator is depressed too much, the selection circuit SC selects the output voltage of the potentiometer po'rs and controls the speed to correspond to that voltage. do.

In other words, constant speed rotation control is performed in which the motor DM feeds back its rotational speed, and not only when the accelerator is depressed too much, but also when the vehicle speed relative to the turning radius is at a critical speed, the speed is regulated to be below the critical speed.

This constant speed rotation setting is achieved by feedback gain adjustment using potentiometers POTs.

Here, when the maximum speed of the electric vehicle is regulated to the speed corresponding to the set value θR9θL when the steering wheel operation angle exceeds the set value θR9θL, a factor of vehicle speed is introduced in comparison with the amount of accelerator depression. Therefore, heavy load (
When the vehicle speed decreases due to a heavy load (e.g. a large load), the output voltage Vo decreases, and even though the output voltage of the potentiometer POTA decreases due to an increase in accelerator pedal depression due to a heavy load, the motor speed is not controlled. is not regulated by the output voltage of the potentiometer P O'rs, and the amount of accelerator depression can be increased to the maximum speed regulated by the steering angle even under heavy loads, preventing deterioration of driving performance under heavy loads. can.

FIG. 4 shows another embodiment of the present invention, and the difference from FIG. 2 is that the switch Sw position is changed and the potentiometer P
The point is that a DC amplifier Amp having a dead zone is provided between the OTs and the selection circuit sc.

That is, the dead band level is set by the Zener voltage of the Zener diode Z1, and the level of the dead band is set by the Zener voltage of the Zener diode Z1. DC amplification is performed using Tr3 etc.

This aims to amplify and clarify the speed detection level.

In the embodiments described above, as shown in FIG. 1, the speed control device equipped with the bypass contactor MS can perform separation control, and can also provide overspeed warnings and the like.

For example, the output voltage of the DC amplifier A rll p in FIG. 4 can be used as a lighting control signal for an overspeed warning lamp, or as an operation control signal for a bypass contactor MS.

In addition, as shown in FIG. 5, a potentiometer Po'r
The output voltage Vo of s is input to the DC amplifier Amp, and the signal passed through the Zener diode Z2 is used as an overspeed warning contactor drop command.

Further, in the embodiment, a case is shown in which one speed limit setting is performed, but this can also be set in two or more stages.

FIG. 6 and FIG. 7 show an example.

The relationship between switches swA and swB with cam CM is shown in FIG. 7. When the bundle operation angle exceeds θR or θL on cam CM, switch SWA closes, and the bundle notch further increases to reach θRM. Or, when θLM is exceeded, the switch SWB closes.

Then, when the switch SWA is closed, the potentiometer P
The output voltage of the OTS is applied to the Zener diode Z1 of the amplifier Amp, and similarly, the switch SWB, when closed, applies the voltage to the Zener diode Z2.

Note that the Zener voltage of z2 is lower than that of zl.

Now, assuming that the switch SWA is closed, the output voltage Vo (rotational speed of the motor) of the potentiometer POTs at that time is relatively low, and if the Zener diode z1 is not conductive, no speed limit feedback is applied.

For example, if the dangerous speed when driving with the steering wheel operating angle cut by the angle θR is 7 km/h, the switch SWA is turned on to try to suppress the vehicle speed to 7 km/h or less, but the vehicle speed becomes 6 km/h. There is virtually no need to slow down.

However, if the bundle operation angle becomes even higher (and exceeds θRM), it is dangerous even at 6 km/h and it is necessary to reduce it to, for example, 4 km/h. In that case, the switch SWB will close, and the Zener voltage of z2 will decrease. Since this is low, the Zener diode z2 becomes conductive, feedback of the speed limit is applied, and the speed is decelerated to the regulated maximum speed.

In this case as well, if the amount of depression of the accelerator is small, no feedback will be applied.

Further, in the embodiment, the turning radius of the electric vehicle can be detected by means such as an optical switch or a semiconductor switch.

Further, the main circuit of an electric vehicle is not limited to a DC/AC chopper, inverter, etc.

As explained above, the electric vehicle speed control device according to the present invention regulates the maximum speed of the electric vehicle to a speed corresponding to the set value when the bundle operation angle is operated beyond the set value. As a result, accidents such as vehicle overturning can be prevented.

Since the maximum speed is regulated by comparing the amount of accelerator depression and retraction with the vehicle speed, there is no reduction in driving performance under heavy loads.

[Brief explanation of the drawing]

1 is a schematic configuration diagram illustrating a conventional speed control device, FIG. 2 is a circuit diagram illustrating an embodiment of the present invention, FIG. 3 is a mechanism diagram illustrating the turning radius detection means in FIG. 2, and FIG. 7 to 7 are circuit diagrams showing other embodiments of the present invention. G: AC speed generator, Ref: diode bridge, C: capacitor, POT
s, PoTA... Potentiometer, SW...
...Switch, LU...Chopper control circuit, S
C: Selection circuit, O20: Timing signal generator, Amp: DC amplifier, Ds,
DA...Diode, Z□t Z 2...
...Zener diode, Tr□, Tr2. Tr3...
...transistor, cH6,610, chopper, M
S, -0-bypass contactor, DM...DC motor, CM...Cam, SW At SWB
·······Microswitch.

Claims (1)

[Scope of Claims] 1. A turning radius detector that detects that the bundle operation angle of the electric vehicle has been operated beyond a set value, and a speed detector that detects the traveling speed of the electric vehicle with a gain that corresponds to the set value. and when the amount of depression of the accelerator is larger than the detection amount of the speed detector introduced by the detection operation of the turning radius detector, the detected amount is used as a speed control signal of the electric vehicle, and the amount of depression of the accelerator is detected. A speed control device for an electric vehicle, comprising: a control circuit that uses the amount of accelerator depression as a speed control signal for the electric vehicle when the amount is smaller than the amount of depression. 2. The speed control device according to claim 1, wherein the control circuit issues a warning when the electric vehicle reaches a regulated maximum speed. 3. The speed control device for an electric vehicle according to claim 1 or 2, wherein the control circuit controls the bypass contactor to fall off when the electric vehicle reaches a regulated maximum speed.