JPS594922B2 - Electric car speed control device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a speed control device for an electric vehicle.

When an electric vehicle, such as a battery forklift, passes through a small turning radius at high speed, there is a risk of the cargo falling, the driver falling, or, depending on the unstable platform, overturning the vehicle.

5. In order to avoid such dangers, the present invention provides a system for detecting the steering angle by installing a device around the steering wheel (variable resistance linked to the steering wheel) and a device for detecting speed in the drive system. At 10 o'clock, when the car is in a dangerous situation, the brakes are applied electrically, and when the speed reaches a certain safe speed, the brakes are released and the speed is prevented from exceeding a certain speed.

On the other hand, the critical range of steering angle and speed also changes depending on the mast position 15 in the case of a battery forklift.

In other words, if the mast is in a lower position, a larger steering angle and higher speed are safe. Therefore, if such a device for detecting the mast position (a variable resistor linked to the mast) is added, better speed control is possible20. Now, when considering the steering angle and speed, there is a dangerous area as shown in the shaded area shown in FIG. 1, and this dangerous area becomes smaller as the mast position becomes lower.

When driving an electric vehicle, the electric vehicle must be operated in a safe area by applying electric brakes to avoid entering the shaded area. The steering angle in the dangerous area is a function of a certain speed, assuming that the dangerous centrifugal force is constant. 30 FIG. 2 shows an embodiment of the speed control device for an electric vehicle according to the present invention, and will be explained in particular by taking the case of a battery forklift truck as an example.

In the same figure, E is a battery, DM is a DC motor, and C
H is a chopper circuit controlled based on an accelerator position signal, 35DFI, DF2 is a flywheel diode, MF, MR are excitation coils of an electromagnetic switch that selects the rotation direction of the motor, and MF is an electromagnetic switch for forward movement: In the excitation coil of the switch, MR is the excitation coil of the reverse electromagnetic switch.

S and S are respectively MFMR and excitation coil M.
These are a forward changeover switch and a reverse changeover switch, which are switched by energizing and deactivating F and MR.

Lf is a field coil, MS is an excitation coil of the tipper short-circuit conductor, and Ms is a tipper circuit short-circuit conductor contact that is opened and closed by energization and deenergization of the excitation coil.
SK is a key switch, and MFX and MRX are make contacts that are opened and closed by excitation coils Mfx and mrx, respectively, when the excitation coils MFX and MRX are energized and deenergized, respectively. MSX is an excitation coil, Msx is a break contact that opens and closes when the excitation coil MSX is energized or deenergized, S is an accelerator switch, SCR, , SCR2 are thyristors, FCl and FC2 are ignition circuits for thyristors SCRl and SCR2, respectively. ,Dl,
D2 is a diode, R1 is a resistor, C1 is a capacitor, D
11 is a Zener Z-diode.

The main circuit section consists of a battery E, a DC motor DM, its field circuit, a chopper circuit CH, etc. Next, the configuration of the speed detection and setting circuit will be described. The speed detection and setting circuit consists of a speed detection circuit SDC and a speed setting circuit SSC.

First, in the configuration of the speed detection circuit SDC, SD is a speed detector, RC is a rectifier circuit, C2 is a capacitor, and R2 to R7
is a resistor, and D3 is a diode. Next, speed setting circuit S
Due to the SC configuration, T1 to T4 are transistors, Dz
2, D23 is a Zener diode, D4 to D6 are two diodes, R8 to Rl6 are resistors, VRl is a variable resistor for detecting the steering angle, R2 is a variable resistor for detecting the mast position, and VR3 is linked to the accelerator (not shown). The accelerator position signal is taken out from the middle tap m of the variable resistor VR3, which is variable. Next, to describe the configuration of the logic circuit LC, CPl and CP2 are voltage comparators, LF is a limit switch that selects forward movement, and L
R is a limit switch that selects reverse, NOR1~N
OR4 is a NOR circuit, 0R1 and 0R2 are OR circuits, Rl7
~R2O is a resistance.

・In addition, regarding the configuration of the auxiliary relay circuit CRC, T5 to T7 are transistors, MSX, MFX, and MRX are excitation coils of the relay, and R2
1 to R23 are resistors. The second
The operation shown in the figure will be explained in detail using FIGS. 1 and 3. Figure 2 shows the steering angle/velocity dangerous area}b1 Figure 3 shows the voltages at various parts in Figure 2. The operation of each part will be explained.

First, when the key switch S is turned on and either the electromagnetic switch switch K or S is turned on, the main circuit of the DC series motor DM that drives the vehicle MFMR is activated as shown in Figure 2. Current flows through a chopper circuit connected to the motor DM and controlling the average voltage applied to the motor DM according to the accelerator signal.

Here, when the forward changeover switch S is switched by the energization of the excitation coil MF of the electromagnetic switch, the field current flows from the bottom to the top of the field MF and moves forward.

At this time, the flywheel diode DFl operates as a so-called flywheel diode when the chopper circuit CH is off. When the vehicle body is moving forward, when the excitation coil MF is deenergized and the excitation coil MR is energized, the electric motor DM operates as a generator, and an electric brake is applied.
The armature generated current is a flywheel diode DF,
cycle. At this time, the flywheel diode DF operates as an armature diode. When high speed and high torque are to be obtained, a chopper shorting conductor is inserted, its contact is closed, and the full voltage of the battery E is applied to the motor DM. In addition, in the present invention, a speed detection setting circuit (SDC, SSC) and a logic circuit LCl auxiliary relay circuit CRC are provided as additional circuits, so that the voltages at points 6, 8, 0, [F], and O can be adjusted. V, V, V, ABDV, respectively.
V, in the speed detection setting circuit, the variable resistors VRl and R2 for steering angle detection and mast position detection are set to 8 points.The more the steering is turned (the smaller the turning radius), The higher the center of gravity, the higher the voltage (see Figure 3).

Further, a voltage lower by the voltage ZV2 of the Zener diode D2 is generated at the 8th point.

An 8-point voltage V is applied to point O when the steering z ring is set at a certain angle or more (the same applies to the mast position, so we will only discuss the steering angle from now on).

A speed detector SD for detecting the rotational speed of the armature of the electric motor DM is directly connected to the 0B point, and its output voltage is rectified through a rectifier circuit RC, and a divided voltage is applied.

When the steering wheel is turned, voltage is applied to resistor R7, so the O point voltage is V. (If the steering wheel is not turned), the voltage will be high. And the O point voltage V. is fed back to 8 points by transistors T2 and T3, and operates in the direction of lowering the motor voltage by raising the conductivity of the chopper circuit CH, that is, the voltage at one point which is Fbi less than the voltage applied to the motor DM. That is, when the steering angle exceeds a certain angle, it operates to suppress the rotational speed of the electric motor DM. Next, the transistor T4 generates a voltage at the 0 point that decreases when the steering angle exceeds a certain steering angle.

Further, a voltage lower by Z, 3 than the 0 point is generated at point [F]. The [F] point voltage is compared with the divided 8-point voltage of the output voltage of the speed detector SD by the voltage comparator CPl, and when the 5-point voltage is higher, that is, the motor DM is rotating at the maximum speed. At this time, the output of the voltage comparator CP becomes high, turning on the transistor T5 and exciting the excitation coil MSX of the auxiliary relay. The relay contact Msx is connected in series with the accelerator switch (limit switch) S, which is turned on when the accelerator is pressed to the maximum. Conductor contact Ms is opened.

Further, when the chopper short circuit conductor is not closed, the chopper short circuit conductor is not closed even if the accelerator is depressed to the maximum. Also, the O point voltage is compared with the 0 point voltage by the voltage comparator CP2, and when the 8 point voltage is higher, the output of the voltage comparator CP2 becomes high and the logic 8
Give the F signal.

Also, when the limit switch LF is turned on and the output of the voltage comparator CP2 is logic ``0'', the NOR circuit NOR3
When the output becomes "1", the transistor T6 is turned on and the excitation coil MFX is excited.

Then, the make contact Mfx closes, energizing the excitation coil MF and enabling the changeover switch SMF to be switched to the right side. Also, if the excitation coil MF is energized, and therefore the forward selector switch SMF is switched to the right side, moving in the forward direction, and turning the steering wheel, the O point voltage decreases (from 8 point voltage). If the output of the NOR circuit NOR3 becomes 0, and the output of the NOR circuit NOR2 becomes 1r,
Transistor T, is turned off, excitation coil MFX is deenergized, its contact Mfx is opened, excitation coil MF is deenergized, and selector switch SMF is switched to the left. On the other hand, at this time, the transistor T7 is turned on, so the excitation coil MRX is energized, its contact Mrx is closed, the excitation coil MR of the reverse electromagnetic switch is energized, and the reverse changeover switch SMR is switched to the right side. , the electric motor DM becomes a generator and applies an electric brake. Next, the above operation will be explained in sequence. For this explanation, as shown in Figure 1, the route (ROut
e) Consider a-b-c-de. At first, I turned on the short-circuit conductor and was driving straight ahead, and as I turned the steering wheel, I reached point a.

At point a, the O point voltage is lower than the 5 point voltage, and no feedback is applied to the accelerator. If you turn the steering wheel further, you will reach point b. At this time, the voltage at point [F] decreases, so the voltage at point 8 is higher.The output of voltage comparator CP is "1". Turn on transistor T, and turn on the excitation coil MS is energized to open its contact Msx. As a result, the chopper shorting conductor falls off. That is, the conductor contact Ms is opened (by deenergizing the excitation coil MS). Therefore, the motor DM is a chopper circuit C
H, and the vehicle moves to running under the control of the chopper circuit CH. At the same time, eight point voltages are generated, and this voltage is applied to the O point, raising the O point voltage. Since this 0 point voltage is higher than the 8 point voltage, the 1 point voltage is raised. In other words, feedback is applied to the accelerator of the throttle, and the motor voltage is suppressed. If you turn the steering wheel further, you will reach point C (see Figure 1).

At this time, the 0-point voltage is decreasing, so the 8-point voltage is higher, and the voltage comparator CP2 output becomes "1", and the excitation of the excitation coils MFX and MRX, that is, the excitation coils MF and MR, is switched. Electric brakes are applied. For this reason, the speed attenuates and when it reaches point d, the 8 point voltage drops below the 0 point voltage,
Although the electric brake is released, the chopper short-circuiting conductor cannot be closed, and the vehicle runs chopper. Since feedback is applied to the accelerator, the speed is attenuated to point e. At this time, the voltage at point 9 is lower than the voltage at point [F], so the excitation of the excitation coil MSX of the auxiliary relay is cut off, and the chopper shorting conductor can be turned on, but feedback to the accelerator is still being applied. Generally, a thyristor SCR2 is inserted in the excitation circuit of the chopper short-circuiting conductor as shown in the figure, and a firing circuit FC2 is connected to the gate of the thyristor SCR2. The ignition circuit FC2 is designed not to operate in this state. Therefore, even if the excitation coil MSX of the auxiliary relay is de-energized at point e, the chopper short-circuiting conductor is not turned on and chopper running with feedback is continued. When the load is heavy, the speed decreases and the 1-point voltage and 8-point voltage cannot reach high voltages, so even if the steering wheel is turned, the foot to the accelerator is
There is no need to put in any /, and a short-circuit conductor can also be inserted.

However, as soon as the chopper short circuit conductor is turned on and the speed increases, the electric brake is not applied for a long time, so the setting voltage ((V) point voltage) and the electric brake Since it is necessary to make a difference in the set voltage (O point voltage) applied, a Zener diode DZ3 is inserted. Also, when going down a slope, the speed increases, so even if there is no 8-point voltage, the O
The voltage at the point and zero point rises, causing the chopper short-circuit conductor to fall off, applying feedback to the accelerator.

Furthermore, as the rotation of the electric motor DM increases, the electric brake is applied. In this embodiment, a variable resistor equipped with an intermediate tap is used as a device for detecting the steering angle.
Although sufficiently good results have been obtained by using VR1 to deal with the dangerous area as shown in FIG. 1, the present invention is not limited thereto, and in order to obtain even better results, If the output of the variable resistor VR, equipped with It can be perceived as a curved line based on reality.

As mentioned above, when using the speed control device for an electric vehicle according to the present invention, when passing through a small turning radius at high speed, it is possible to avoid problems such as falling of cargo, falling of the driver, or the case of an unstable machine platform. This has extremely great effects, such as eliminating the risk of rollovers.

[Brief explanation of the drawing]

FIG. 1 and FIG. 3 are explanatory diagrams of the operation of the present invention, and FIG. 2 is a circuit diagram showing an embodiment of the speed control device for an electric vehicle according to the present invention, in which E is a battery and DM is a direct current. Electric motor,
5CH is the chopper circuit, MS} and Ms are the excitation coil diagram of the chopper circuit shorting conductor and its conductor contact, VR is the variable resistor for steering angle detection, VR3
is a variable resistor, Lf is a field coil, MF and MR are excitation coils of the electromagnetic switch, }, , S are respective changeover switches, and SDC is ? Degree circuit y? Sc is a speed setting circuit,
LC indicates a logic circuit, and CRC indicates an auxiliary relay circuit.

Claims (1)

[Claims] 1. In an electric vehicle in which a DC motor having a field circuit is connected in series to a DC power source such as a battery via a chopper circuit, and speed control is performed by controlling the conductivity of the chopper circuit based on an accelerator position signal. , the speed detection means of the DC motor and the steering angle detection means of the electric vehicle are provided, and in order to suppress the speed below the critical speed of the vehicle, which changes according to a certain function according to the steering angle, the speed exceeds the critical speed. When the chopper short-circuit contactor is closed, the electric brake is applied, and when the chopper short-circuit contactor is closed, the chopper is released, and when the detected value of the steering angle detecting means exceeds a predetermined value, the output of the speed detecting means is converted into the accelerator position signal. Relatedly, a speed control device for an electric vehicle, characterized in that the accelerator signal is changed in a direction that reduces the conductivity of the chopper circuit, so that the speed during chopper running is suppressed to a speed that is a function of the steering angle or less.