JPH01126102A - Braking device for electric motor vehicle - Google Patents

Abstract

PURPOSE:To prevent abnormal braking under running from being generated, by inhibiting the chopping conduction of a magnet brake when a driving motor is set in an over-current state, and by executing continuous conduction. CONSTITUTION:When accelerator signals CH1 and CH2 come together to an L, then signal V4 comes to an H, and signal V5 is slowly increased. Then, for a specified time, current is continuously conducted to a magnet brake coil 10, and a brake is worked. After the lapse of the specified time, the rise of the signal V5 is performed, and so by chopping signal from a comparator 8, chopping conduction is executed on the magnet brake coil 10. In the meantime, when the current of driving motors 14, 15 comes to a set value or more during running, then signals V11, V12 come to an L. Then, the signal V5 is lowered, and the continuous conduction is executed on the magnet brake coil 10, and the working of the brake is suppressed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a control device for an electric vehicle, and in particular to an electric vehicle control device that prevents abnormal braking operation and brake lining burnout in a non-excitation operated automatic magnetic brake. This relates to a braking device for a vehicle.

[Prior Art] A conventional example is shown in FIGS. 3 and 4. Of these, FIG. 3 shows an example of a control circuit in a conventional automatic magnetic brake device, and FIG. 4 shows signals of various parts in the circuit of FIG.

In FIG. 3, a 2CH system having two drive motors is shown. The conventional example shown in FIG.
An AND circuit 1 that calculates the logical product of accelerator signals for the motors HI and CH2, an integrating circuit 3 consisting of a diode 2, a resistor R8, and a capacitor C1, and an output that compares the output of this integrating circuit 3 with a fixed threshold value. a comparator 4 that generates a diode 5, an integrating circuit 6 consisting of a resistor R2 and a capacitor C8, an oscillator 7 that generates a reference triangular wave (or sawtooth wave), and an output of the integrating circuit 6 and a reference triangular wave. a comparator 8 that compares and generates an output, an AND circuit 9 that calculates the AND of the output of the comparator 4 and the output of the comparator 8, a magnetic brake coil lO, a battery 11,
It is composed of a transistor 12 that controls the power supply from the battery 11 to the magnetic brake coil 10, and a power supply circuit 13 that supplies power Vcc to each part.

In the conventional device shown in FIGS. 2 and 3, when the accelerator is not depressed, the C for the two drive motors is
The accelerator signals of HI and CH2 are rH, which indicates neutrality.The output signal v of AND circuit 1 is rH, which indicates stop when both accelerator signals are rH, and the vehicle is not running otherwise. The signal v, which becomes "L" as shown in FIG.
A signal v2 is generated which is accompanied by a rising delay according to c1 and falls immediately upon falling. Comparator 4 has signal v2 as threshold value V,
It outputs a signal v4 which becomes "L" when the voltage exceeds the threshold value, and which becomes rH at other times. Signal v4 is connected to diode 5. After passing through the integrating circuit 6, a signal V is generated, which is accompanied by a delay in rising due to a time constant R1Cl when rising, and immediately falls when falling.

The comparator 8 converts the reference triangular wave signal 6 of the oscillator 7 into the signal V
, it becomes rH, and otherwise it outputs a signal v7 that becomes "L". The AND circuit 9 generates a signal V which is the logical product of the signal v4 and the signal V.

Output. Transistor 12 becomes conductive in accordance with signal v8, and as a result, current flows from battery 11 to magnetic brake coil 10 and it is excited.

The signal V is as shown in FIG. 4, and the magnetic brake is of a non-excitation type.

Therefore, when the vehicle is stopped, it is in a non-energized braking state, and when it starts traveling, it is initially fully conductive for a certain period of time, and the full voltage is applied to the magnetic brake coil, which attracts the brake disc and turns the brake off.

After that, the chopping operation starts and the electricity starts to be energized intermittently, the non-conduction period gradually increases, and finally, the duty is 50% or so, and the brake is kept off intermittently. be done.

This operation occurs because the magnetic brake has hysteresis characteristics. For example, when the battery voltage is E (V), the minimum on-voltage is 0.7E, and the maximum off-voltage is 0.3E. Magnet specifications have been established.

[Problem that the invention seeks to solve]

Non-excitation operated magnetic brakes are excellent from a fail-safe point of view because they always enter a braking state if there is no voltage for some reason. However, in order to provide a predetermined braking torque, it requires about twice as much electric power as the excitation-operated type, which also increases the cost. Therefore, it is not possible to provide much leeway in the braking torque.

Now, in the state shown by A in Figure 4 where the brakes are released while the vehicle is running, if the brake disc becomes open (brake on) for some reason even though the power is on, a chopping operation is performed. The brake will not return to the off state.

On the other hand, since there is not enough braking torque to spare, a situation may arise where the vehicle continues to travel in a braked state even if the speed decreases to some extent. When this situation occurs, the fourth
Unless you stop as shown in B in the diagram and restart as shown in C, you will not be able to return to normal conditions, and if you continue to drive forcibly, the brake lining (facing) will burn out. . Note that the above-mentioned problems are the same even when there is only one drive motor.

[Purpose of the invention]

The present invention aims to solve the problems of the prior art as described above, and provides a braking system for an electric vehicle equipped with a non-excitation operated magnetic brake that employs a chopping operation method. It is an object of the present invention to provide a braking device for an electric vehicle that can automatically return to a normal state and prevent burnout of a brake lining when the brake is turned on for some reason.

[Means for solving problems]

The braking device for an electric vehicle of the present invention is of a non-excitation type, and after turning on the brake by continuously energizing the brake coil, maintains the brake on state by a chopping operation that intermittently cuts off the energization to the brake coil. In a braking device for an electric vehicle equipped with a magnetic brake, an overcurrent detection means generates a detection signal when a drive motor is in an overcurrent state, and the overcurrent detection signal inhibits the chopping operation and continuously energizes the brake coil. The system is equipped with a control means for performing the following steps.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. Here, the same reference numerals are used for the same configurations as in the conventional example described above.

The embodiment shown in FIG. 1 includes 2CH drive motors 14 and 15 including a drive circuit, a motor current detection resistor R3, an overcurrent detection circuit 16 including a threshold voltage setting resistor R4, and a comparator COM. 17 and diodes 18 and 19.

FIG. 2 shows signals of various parts in the circuit of FIG. 1, and is used to explain the operation of the magnetic brake device of the present invention.

When the transistor Tr is turned on, each drive motor 14, 15 is supplied with current from the battery 11 and rotates the motor M, thereby rotating the wheels of an electric vehicle or the like and generating driving force. . Drive motor 14.1
During the operation of 5, a voltage is generated in the current detection resistor R1 in each of the overcurrent detection circuits 16 and 17.

The overcurrent detection circuits 16 and 17 compare the voltage of the resistor R1 and the set voltage of the dark value setting resistor R4 to generate an output signal vI l + V l N. This signal vl
l+'V, yo is the drive motor 14. as shown in FIG.
r L J only in the overcurrent condition of 15, and rl(J in all other cases).

In the overcurrent detection circuits 16 and 17, the comparators COM are composed of operational amplifiers, and the output resistance thereof is sufficiently smaller than the resistance R2 in the integrating circuit 6. Therefore, the signal vII+vl
! When either becomes rl, J, the output signal V, of the integrating circuit 6 becomes rlJ, the output signal V, of the integrating circuit 6 is pulled down to "L".

Therefore, the output signal v7 of the ratio angle device 8 is r)IJ
Therefore, the drive signal V for the transistor 12,
This period also becomes r) (J.

Therefore, if an abnormal release of the brake disc occurs at point A in Fig. 2, the overcurrent detection signal of the drive motor based on this is used to temporarily and continuously energize the brake coil to brake the brake. Control is performed so that the chopping operation is turned off and the chopping operation is resumed after the overcurrent condition is resolved.

Therefore, the normal state is immediately restored without controlling the magnetic brake by stopping and restarting the motor as shown at B-C in FIG. 4.

[Effects of the Invention] As explained above, according to the present invention, when an abnormal condition occurs in which the brake is turned on while driving in the braking system of an electric vehicle having a non-excitation activated magnetic brake, the brake is automatically turned off. and return to normal state,
It is possible to effectively prevent abnormal braking during driving that occurs when the brake disc adsorption is unstable due to an abnormal drop in the magnet supply voltage due to an excessive gap between the brake coil part and the disc part, and also to prevent burnout of the brake lining. It is possible to provide a control device for an electric vehicle that is unprecedented and excellent.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention, FIG. 2 is a time chart showing various signals in the circuit of FIG. 1,
FIG. 3 is a diagram showing a circuit configuration of a conventional magnetic brake device, and FIG. 4 is a time chart showing signals of various parts in the circuit of FIG. 1.9...AND circuit, 2.5.18.19.
...Diode, 3,6...Integrator circuit,
4, 8... Comparator, 7... Oscillator, 1
0...Magnetic brake coil, 11...
...Battery, 12...Transistor, 13
...Power supply circuit, 14.15 ... Drive motor, 16.17 ... Overcurrent detection circuit. Patent applicant: Suzuki Automobile Industry Co., Ltd. Figure 2

Claims (1)

[Claims] (1) A non-excitation type magnetic brake that turns on the brake by continuously energizing the brake coil and then maintains the brake on state by a chopping operation that intermittently cuts off the energization to the brake coil. In a braking device for an electric vehicle, the overcurrent detection means generates a predetermined detection signal when the drive motor becomes overcurrent, and the overcurrent detection signal inhibits the chopping operation and continuously energizes the brake coil. What is claimed is: 1. A braking device for an electric vehicle, characterized by comprising a control means for causing the braking to occur.