JPS6130481B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric vehicle control device for electric vehicles such as forklift trucks having a plugging control function.

Conventionally, it has been said that the characteristic 50 of the chopper conductivity D with respect to the accelerator depression angle θ in an electric vehicle control device used for a forklift or the like is better than the characteristic 60 shown in FIG. The reason for this is that the accelerator can be adjusted over a wide range at low speeds. In such a conventional device, when braking is adjusted using the accelerator during plugging braking, control is performed using a characteristic such as characteristic 61 in FIG. 1.

However, in such a characteristic 61, since the chopper conductivity D changes approximately in a region 62, there is a drawback that the braking torque adjustment range is small.

In order to solve the above-mentioned drawbacks, the present invention is configured so that, during power running, the conductivity of the conductivity variable means with respect to the operating angle of the accelerator means increases at a higher rate as the operating angle of the accelerator means increases. By making the conductivity of the conductivity variable means increase linearly in approximately direct proportion to the operating angle of the accelerator means during plugging braking,
It is an object of the present invention to provide an electric vehicle control device that allows easy and ideal operation of an accelerator means during plugging operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Below, drawings showing an embodiment of the method and apparatus of the present invention will be described.

In FIG. 3, 1 is a DC motor for driving an electric car having a field winding 2 and an armature 3, 4 is a thyristor chopper serving as a conductivity variable means, and 5 is a 4
is a flywheel diode that allows the motor current to flow when the motor is cut off, 6 is a plugging diode that allows the generated current generated in the winding of the armature 3 to flow during plugging braking, and 7 is a variable resistor that constitutes the accelerator means (not shown). It is a variable resistor in which the movable contact 8 moves from the fixed contact 9 to 10 when the accelerator pedal is depressed, and it has a linear characteristic type that is commercially available as a normal type, that is, the output is directly proportional to the amount of operation. The resistance value changes linearly.

8 is a movable contact of the variable resistor 7, at which the output voltage of the accelerator means 7 appears. 11 is a resistor for setting the maximum chopper conductivity, and 12 is a resistor for setting the minimum chopper conductivity. 13 is a constant current circuit that supplies a constant current to its output. 14 is a delay capacitor for soft start, and 15 is an operational amplifier called a voltage follower. 16 and 17 are diodes for backflow prevention, 18
In this type of circuit, a well-known voltage controlled oscillator is capable of changing the ratio of the output voltage between "1" and "0" states in direct proportion to the input voltage. 19 is a plugging braking detection circuit, and a known circuit can be used.

20 is a comparator which serves as a switching means, and when the plugging braking detection circuit detects that the plugging state is present, the voltage at the input terminal (-) of the comparator 20 becomes higher than the voltage at the input terminal (+), and the internal The switching state at is reversed, and the potentials at the first output terminal 21 and the second output terminal 22 are reversed. 23 is a conductivity control signal generation circuit, which is a well-known on-pulse generation circuit 2.
4 and an off-pulse generating circuit 25. 26,2
7 is a main circuit opening/closing contactor constituting the plugging brake circuit.

Further, 30 is a low resistor constituting a low resistance circuit, 3
1 and 32 are high resistors forming a high resistance circuit, and 34 is an output terminal of the high resistance circuit. Further, 35 indicates an accelerator circuit.

Next, the operation of the above configuration will be explained.

First, of the main circuit switching contactors 26 and 27 in the illustrated state, the contactor 26 is switched from the illustrated normally closed state to the normally open state. Then, when the chopper 4 is operated by the impulse generating circuit 24 and the off-pulse generating circuit 25 in synchronization with the voltage controlled oscillator 18, power is supplied to the DC motor 1 from the 48 [V] DC power supply 40.

At this time, if the vehicle is in the power running state, the plugging detection circuit 19 does not operate, and therefore the first output terminal 21 of the comparator 20 becomes conductive, reaching the ground potential, and the second output terminal 22 is cut off. It has become a state. In this state, the high resistors 31, 3
2 and the diode 17 can be ignored, and the potential of the movable contact 8 of the variable resistor 7 is applied almost unchanged to the non-inverting input of the operational amplifier 15 via the high resistor 31. Non-ground side 45 of capacitor 14 which becomes output terminal
is approximately equal to the potential of the movable contact 8. The potential of the non-ground side 45 of this capacitor 14, that is, the input potential of the voltage controlled oscillator 18, is approximately determined by the position of the movable contact 8 of the variable resistor 7, which serves as an accelerator means.

Although a general linear characteristic is used as the variable resistor 7, by appropriately selecting the resistance value of the variable resistor 7 and the resistance value of the low resistor 30, the accelerator pedal depression during steady state, that is, during power running, can be controlled. The charging voltage of the capacitor 14 with respect to the angle θ, that is, the chopper conductivity D changes in a curved manner as shown in the characteristic 50 in FIG. Become.

Note that when the accelerator means 7 is suddenly depressed, the capacitor 14 is charged with a constant current by the constant current circuit 13 to a potential equivalent to the accelerator position at which the accelerator is depressed, so that the chopper conductivity D is shown in FIG. As shown, the acceleration increases linearly with the passage of time t, and the acceleration feeling improves.

Next, a case where the vehicle enters a plugging braking state will be described. In this case, the plugging detection circuit 19 operates and the comparator 20 is inverted, so that the first output terminal 21 is cut off and the second output terminal 22 is made conductive.

At this time, since the resistance values of the high resistors 31 and 32 are much larger than the resistance values of the voltage dividing resistors 11 and 12 and the variable resistor 7, the voltage of the movable contact 8 is proportional to the accelerator depression angle θ. Since the voltage changes in direct proportion and this potential change is divided by the high resistance resistors 31 and 32, the output terminals 34 of the high resistance circuits 31 and 32, which are input to the voltage follower 15, are connected linearly to the accelerator depression angle θ. A changing voltage appears. For this reason, the change in the input voltage of the voltage controlled oscillator 18 with respect to the accelerator depression angle θ also becomes linear, and the characteristic of the chopper conductivity D becomes the characteristic 55 in FIG.
It becomes a straight line as shown in .

By having such a linear characteristic, braking torque control during plugging braking can be easily performed by appropriately changing the accelerator operation angle.

As described above, in the present invention, the plugging braking circuit maintains a low resistance circuit in the linear characteristic type variable resistor in the non-plugging state, and maintains the low resistance circuit in the linear characteristic type variable resistor in the plugging state. Since the high-resistance circuit is made to last, it is possible to use a generally commercially available linear variable resistor, which is inexpensive, easy to use, and easy to manufacture.Furthermore, when electric cars are powered In this case, as the operation angle of the accelerator means is increased, the rate of increase in the conduction rate of the conduction rate variable means becomes larger.Acceleration and deceleration operations during power running are easy and the driving feeling is good. Since the conductivity change characteristic with respect to the operating angle of the means is made substantially linear, there is an excellent effect that smooth braking can be easily performed.

[Brief explanation of the drawing]

Fig. 1 is a characteristic diagram showing the characteristics of the conventional device, Fig. 2 is a characteristic diagram showing the characteristics of an embodiment of the method and device of the present invention, and Fig. 3 is an electric circuit showing an embodiment of the method and device of the present invention. 4 are characteristic diagrams showing examples of changes in chopper conductivity over time in the circuit shown in FIG. 3. DESCRIPTION OF SYMBOLS 1...DC motor, 4...Conductivity variable means, 7...Variable resistor serving as accelerator means, θ...Depression angle serving as operation angle, D...Conductivity, 8...Movable contact, 20...
Switching means, 18, 23...Conductivity control signal generation circuit, 21...First output terminal, 22...Second output terminal, 26, 27...Contactor forming a plugging control circuit, 30...Low resistance circuit, 31, 32...High Resistance circuit, 34... Output terminal of high resistance circuit, 35...
accelerator circuit.

Claims (1)

[Claims] 1. conductivity variable means for adjusting the running speed of the electric vehicle by changing the voltage applied to the DC motor;
a plugging braking circuit that causes the DC motor to perform plugging braking; and a conductivity control signal generation circuit that is connected to the conductivity variable means and generates a signal that controls the conductivity of the conductivity variable means. an accelerator circuit that controls the conductivity of the conductivity variable means via the conductivity control signal generating circuit, and the accelerator circuit has a switching state that is inverted when the plugging braking circuit is in the plugging state. A switching means in which a first output terminal is in an on state and a second output terminal in an off state when not plugged, and a variable resistor of a linear characteristic type that, when operated, generates an output voltage at a movable contact according to the amount of operation. a low resistance circuit connected between the movable contact of the variable resistor and the first output terminal of the switching means; and a low resistance circuit connected between the movable contact of the variable resistor and the second output terminal of the switching means. An electric vehicle control device comprising: a high resistance circuit whose output terminal is connected to the conductivity control signal generation circuit.