JP2807839B2 - Electric vehicle speed monitoring method - Google Patents

Description

Description: Object of the Invention (Field of Industrial Application) The present invention relates to a vehicle speed monitoring method for preventing an electric vehicle from running at a vehicle speed exceeding a speed limit value. .

(Prior Art) Recently, electric vehicles as shown in FIG. 6 are becoming widespread. The electric vehicle has been developed with the main purpose of expanding the range of activities of the elderly and the physically handicapped, instead of a wheelchair and a cane, but also in cases where golf players move between courses. It is useful.

Since this kind of electric vehicle is often used by the elderly and the physically handicapped, as described above, the vehicle speed (speed) during running must be extremely slow. For this reason, various measures have been taken even in the past. One of them is that, even when the output of a traction motor mounted on an electric vehicle is maximized,
Structural or electrical restrictions were imposed so that only a vehicle speed of 6 km / h could be achieved. The running motor is adapted to be able to adjust its rotation speed by operating an accelerator lever 2 attached to a handle portion 1 of the electric vehicle. In itself, the electric car was braked.

(Problems to be Solved by the Invention) A conventional electric vehicle has an acceleration range of 0 to 6 km / h in a plurality of stages (generally, low speed,
The speed could be changed to three speeds (medium speed, high speed). Therefore, the driver can select the vehicle speed according to his / her driving ability and road conditions. However, on a downhill, even if the driver wishes to drive cautiously and selects a low speed shift range, the vehicle speed increases due to the inertia according to the total body weight, and the vehicle speed (the low speed range Acceleration range). Also, when traveling on a steep slope with a steep slope, or when the control system of the traveling motor breaks down, 6 km / h
In some cases, the vehicle speed exceeded the threshold. When this happens,
The driver may be in a hurry, and may not be able to operate the brake lever 3 or even release his hand from the accelerator lever 2. for that reason,
It is very dangerous.

The present invention has been made in view of the above circumstances, and ensures that an electric vehicle never runs at a speed higher than a vehicle speed predicted by a driver, thereby ensuring safety of the driver and the like. An object of the present invention is to provide a new vehicle speed monitoring method for an electric vehicle (hereinafter, referred to as the method of the present invention).

[Summary of Invention] (Means for Solving the Problems) The gist of the method of the present invention is to provide a method for monitoring the speed of an electric vehicle in which forward and backward movements can be shifted to a plurality of stages with different upper limit set speed values. In the electric vehicle, the driving signal and the braking signal are mixed, and the starting signal or the terminating signal is added by repeatedly inputting a pulse train to which a neutral signal is added to a traveling motor, and the electric vehicle is driven to travel. At the time of transmission, an average value of the vehicle speed is calculated by continuously measuring the generated voltage induced by the traveling motor, and the pulse formation is performed so that the average value of the vehicle speed at each stage of the shift is equal to or less than the upper limit set speed value. The duty ratio of the drive signal occupying the entire row is controlled, and the abnormal speed is compared with the vehicle speed average value by comparing the average speed value with a speed limit value designed to be slightly higher than each upper limit set speed value of each speed change stage. If it is known is the point to actuate the appropriate emergency stop mechanism.

(Operation) By setting speed limit values slightly higher than the respective upper limit speed values for the forward and reverse speeds, the speed limit value is compared with the vehicle speed of the electric vehicle, and the speed is abnormal. Speed can be detected. When it is detected that the vehicle speed is abnormal, the electric vehicle is stopped by activating an appropriate emergency stop mechanism for mechanically stopping the rotation of the traveling motor, for example. . As the vehicle speed of the electric vehicle to be compared with the speed limit value, an average vehicle speed value for actual traveling is required, and the average vehicle speed value is obtained as follows. In other words, the rotational speed of the traveling motor can be changed by changing the duty ratio of the “drive signal” occupying the entire pulse train, so that the vehicle speed (upper limit set speed) of each speed change stage of the electric vehicle can be obtained. Value) is controlled. After all, since the traveling motor has a constant interlocking relationship with the driving wheels of the electric vehicle, if the rotational speed of the traveling motor is measured,
The current vehicle speed of the electric vehicle can be known.
Therefore, in the pulse train, when the "neutral signal" added to the start or end of the pulse train is transmitted, utilizing the fact that the traveling motor operates as a generator, the power generation voltage induced at this time is used. The rotation speed of the traveling motor was measured. However, from the value obtained by this measurement, only the instantaneous vehicle speed can be obtained.
The vehicle speed average of the electric vehicle is determined by repeatedly performing the above operation every time the "neutral signal" is transmitted and calculating the average of the obtained values.

(Examples) Hereinafter, the present invention will be described with reference to the drawings showing the examples.

FIG. 1 is a flowchart showing the procedure of the method of the present invention. According to the method of the present invention, the average speed value of the actual running of the electric vehicle is compared with the limit speed values set individually according to the shift range during the running, and the abnormal speed is detected by this comparison. In such a case, an appropriate emergency stop mechanism is operated. In carrying out the method of the present invention, a control system as shown in FIG. 2 is used. The control system is housed in the electric vehicle shown in FIG. 6 and the like at a location 1a shown in the figure. First, this control system will be briefly described.

The control system, based on various signals transmitted from the central processing unit 4 (hereinafter, referred to as CPU), controls the field-effect transistors 5, 6, 7 (hereinafter, referred to as FET) and the forward / reverse relays 8, 9, or The electromagnetic brake 11 and the like are actuated and wired so as to control the rotation state (acceleration / deceleration or stop) of the traveling motor 10. For example, when moving the electric car forward, CPU4
First, it sends a "drive signal" to FETs 5 and 6, bringing FET 5 into a connected state and putting FET 6 into a disconnected state.
Each of the contacts 8a and 9a of the forward and reverse relays 8 and 9 is connected to the Nc side. Also, of course, the two-stage amplification type transistor 12 is turned on, and the electromagnetic brake 11 is released. Accordingly, electricity flows to abcdcghknmlno and the traveling motor 10 rotates forward. By the way, if you keep the power supply state as it is,
The rotation speed of the 10 increases, and the speed of the electric vehicle increases accordingly. Therefore, the CPU 4 transmits a “braking signal” in which the connection states of the FETs 5 and 6 are opposite to each other, and suppresses the rotation speed of the traveling motor 10. That is, when the FET 5 is turned off and the FET 6 is turned on by the "braking signal", the dghhmk
A closed circuit leading to -lnfed is formed. In this case, the traveling motor 10 automatically operates as a generator because the supply of electricity is stopped. Since the electricity induced by the traveling motor 10 flows so as to circulate through the closed circuit and is applied to the traveling motor 10, in the traveling motor 10, Fleming's left-hand and right-hand rules are used. Acting at the same time, dynamic braking (braking brake) occurs. Therefore, by continuously transmitting the “drive signal” and the “braking signal” to the traveling motor 10 in an appropriately mixed state, the rotation speed of the traveling motor 10 (vehicle speed of the electric vehicle) Can be kept constant at a predetermined value. On the other hand, to move the electric vehicle backward, each contact 8 of the forward / reverse relays 8 and 9 is required.
If both a and 9a are switched to the No side, electricity is ab-
The running motor 10 rotates in the direction of cdgjkhhilo-no-no.

The electric vehicle driven and controlled by the control system as described above includes:
As described above, the gear can be shifted to a plurality of gears (three gears in the front and rear gears in this embodiment) for each of forward and backward movements. Each stage of this shift has 0
An upper limit set speed value according to the number of gears is set in an acceleration range of up to 6 km / h, and in an acceleration range of 0 to 3 km / h when the vehicle is reversing. Each upper limit set speed value in each shift speed is held by controlling the mixture ratio of the “drive signal” and the “brake signal” transmitted from the CPU 4.

According to the method of the present invention, when the electric vehicle is running in a certain shift range, if the actual vehicle speed exceeds a certain upper limit set speed value in the shift range to some extent, it is determined that it is an abnormal speed. I have to do it.
Therefore, in addition to the above-mentioned upper limit set speed value, a limit speed value as shown in the following table is also set for each gear stage (in the table, the upper limit set speed value is simply set. Speed limit and the speed limit value is simply written as speed limit). That is, as apparent from this table, for example, when the forward low speed range is selected, when the accelerator lever (reference numeral 2 in FIG. 6) is fully operated, the traveling motor 10 Outputs to achieve a vehicle speed of 2.0km / h, but when traveling on a steep downhill, the vehicle speed of the electric vehicle exceeds 2.0km / h and 3.8km / h
Is reached, it is determined that this is an abnormal speed at the time of low speed forward.

Next, in the method of the present invention, specific means for determining whether or not the vehicle speed exceeds the speed limit value of each shift speed, that is, whether or not the speed is abnormal will be described. As a matter of course, in detecting an abnormal speed, first, it is necessary to know the vehicle speed related to actual traveling. This is because the actual vehicle speed is not uniquely controlled by the selected position of the shift range or the degree of input of the accelerator lever (see reference numeral 2 in FIG. 6). Is different each time. Therefore, in detecting the vehicle speed, a "neutral signal" that does not belong to any of the signals is periodically added to the "drive signal" and the "brake signal" transmitted from the CPU 4 to the FETs 5 and 6, A pulse train which forms one cycle is formed by the presence of the "neutral signal" (the pulse train is described later). That is, when this "neutral signal" is transmitted from the CPU 4, both of the FETs 5 and 6 are switched to the non-connection state. Therefore, the running motor 10
Receives the inertial rotation from the drive wheels and operates as a generator. The generated voltage induced by the traveling motor 10 is also returned to the power supply unit 15 via the FETs 5 and 6 and the diodes 13 and 16 incorporated in parallel with each other. Rotation speed detector connected between
14 will also be applied. To illustrate this situation,
As shown in FIG. In the following, "neutral signal"
Is called N signal, taking the initials of the neutral signal,
The “drive signal” is similarly referred to as an A signal from the accelerator signal, and the “brake signal” is similarly referred to as the B signal from the brake signal. As is apparent from FIG. 3, when the N signal is transmitted, the traveling motor 10 is in a no-load state. Voltage keeps a constant value. Therefore, the rotation speed of the traveling motor 10 can be obtained based on this voltage value, and the current vehicle speed of the electric vehicle can be calculated from the rotation speed.

By the way, as shown in FIG.
One cycle consists of 50 steps.
The step advances by each of the A signal, the B signal, and the N signal, which are transmitted one pulse per 5 / 10,000 seconds (0.5 ms) (the time required for one cycle is 25 ms). The N signal is always positioned at the start or end of the pulse train, and
The pulses are continuous. That is, even if the vehicle speed of the electric vehicle can be calculated at the time of transmitting the N signal as described above, the vehicle speed is only instantaneous for a very short time (1 to 1.5 ms) when the N signal is transmitted. . Therefore,
In the method of the present invention, a voltage value detected by the rotation speed detecting unit 14 is measured for each N signal that is transmitted each time the pulse train is repeated, and the voltage value is measured for a predetermined time (for example, 3 times). (For about 2 seconds), and the average value of the vehicle speed is obtained from a plurality of obtained values. As shown in FIG. 5, the mixing ratio of the A signal in the entire pulse train is referred to as a duty ratio. As the duty ratio decreases, the ratio of the B signal in the pulse train increases. The speed of the electric vehicle can be reduced. Conversely, as the vehicle speed increases, the ratio of the A signal increases, and the vehicle speed of the electric vehicle can be increased. However, no matter how the duty ratio changes, the N signal does not become non-existent in the pulse train unless the electric vehicle undergoes an excessive runaway condition. Therefore, the calculation of the vehicle speed average value as described above is performed regularly and reliably.

As described above, when the average value of the vehicle speed related to the actual running of the electric vehicle is calculated, the average value of the vehicle speed is compared with the speed limit value of each speed change stage. When an abnormal speed is detected by this comparison, an appropriate emergency stop mechanism is operated. As the emergency stop mechanism, for example, the electromagnetic brake 11 shown in FIG. 2 can be mentioned. That is, the two-stage amplification type transistor 12 may be turned off. However,
If the vehicle is traveling with the medium or high speed range selected and the vehicle is switched to the next lower range during the traveling, the speed limit value will also be one lower with the switching. Will be transferred to However, since the vehicle speed of the electric vehicle is not suddenly reduced at the same time as the shift range is switched, the vehicle speed may exceed the limit speed set in the shift range after the switch.
Even in such a case, if the emergency stop mechanism operates uniformly, it is rather dangerous. Therefore, when the shift range is switched, calculation of the vehicle speed average value or comparison of the vehicle speed average value with the speed limit value is performed. It is advisable to suspend for a while (for a period of 2 to 3 seconds). An accelerator lever (reference numeral 2 in FIG. 6)
In this case, the brake is applied to the electric vehicle as described above, so that the average value of the vehicle speed is calculated or the average value of the vehicle speed is compared with the speed limit value. Should be temporarily suspended.

Note that, unlike the above-mentioned emergency, during normal traveling, the average value of the vehicle speed obtained from the voltage value at the rotation speed detecting unit 14 is used as the upper limit set speed value of the selected shift range and the accelerator lever. , And the duty ratio is changed in accordance with the difference to control the vehicle speed of the electric vehicle.

(Study of Another Mode) Electric vehicles include a wheelchair type and a cart type, as well as a passenger car type as shown in FIG. 6, and an industrial vehicle type such as a forklift.
The method of the invention can be carried out for all these types. As described above, the detailed configuration of the method of the present invention can be appropriately changed according to the embodiment.

[Effects of the Invention] As is clear from the above description, according to the vehicle speed monitoring method for an electric vehicle according to the present invention, the pulse train for pulse-controlling the traveling mo motor includes a driving signal, a braking signal, It consists of a neutral signal added to the start or end, accelerates by a drive signal, decelerates by a brake signal, and detects a motor speed by a neutral signal. Moreover, the time required for one cycle of the pulse train is, for example, 25 ms, and the time during which the neutral signal is output is 1 to 1.5 ms.
Is instantaneous. For this reason, the torque is applied to the traveling motor for almost the entire traveling time, and there is no runaway even on a downhill. This means that the speed control of the electric vehicle by the conventional pulse control is such that the traveling motor is turned ON (corresponding to the drive signal of the present invention) by pulse control, and OFF (one of the neutral signal or the brake signal of the present invention). If the OFF signal is equivalent to the neutral signal of the present invention, no torque is generated in the traveling motor in a no-load state such as a downhill (a so-called free state). It is extremely groundbreaking and extremely safe given the risk of runaway and the risk of runaway. When the OFF signal corresponds to the braking signal of the present invention, the motor speed cannot be detected, and the speed of the electric vehicle cannot be detected unless another method is used.

Furthermore, according to the vehicle speed monitoring method for an electric vehicle of the present invention, different speed limit values are set for each of the gear stages. Therefore, when the electric vehicle attempts to run at a speed higher than the vehicle speed predicted by the driver (acceleration range of the selected range), the driver does not need to perform any special operation.
The emergency stop mechanism of the electric vehicle is activated. Therefore,
Safety will be ensured not only for the driver but also for those around the driver. It should be noted that a steep downhill that exceeds the range of the control ability is very dangerous because the vehicle is accelerated in relation to the total weight of the vehicle body. Often selected. However, in the method of the present invention, the low-speed and medium-speed shift ranges are set to correspondingly low values for the speed limit value, so that the vehicle speed at the time when the emergency stop mechanism operates is also relatively low, The impact at the time of stoppage is small. Further, the control system also has a number of excellent advantages such that the circuit is disconnected at the time when the operating voltage is low, so that unnecessary trouble does not occur.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a flowchart of the method of the present invention, FIG. 2 is a circuit diagram showing a control system used in carrying out the method of the present invention, and FIG. 3 is a drive signal and a braking signal. FIG. 4 is a diagram showing the relationship between the motor current and the voltage of the rotation detector with respect to the neutral signal, FIG. 4 is a diagram showing an example of a pulse train, FIG. 5 is a diagram for explaining the duty ratio in the pulse train, FIG. FIG. 2 is a perspective view showing the entire electric vehicle. 2 ... Accelerator lever, 4 ... Central processing unit (CPU) 5,6,7 ... Field effect transistor (FET) 8,9 ... Forward / reverse relay, 8a, 9a ... Contacts 10 ... Motor for traveling , 11 ... electromagnetic brake 14 ... rotation speed detector, 15 ... power supply

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yukihiro Murakami 1-2-5, Kinuyama, Matsuyama-shi, Ehime Prefecture Shikoku Seisakusho Co., Ltd. In-company (72) Inventor Hiroshi Sano 4-2-26-Nishinakajima, Yodogawa-ku, Osaka-shi, Osaka Tecor System Co., Ltd. (56) References JP-A-49-109815 (JP, A) JP-A-53- 69316 (JP, A) Japanese Utility Model Showa 53-115510 (JP, U) Japanese Utility Model Utility Model Showa 55-102302 (JP, U) Japanese Patent Publication No. 53-25924 (JP, B2) (58) Fields surveyed (Int. ⁶ , DB name) B60L 3/00 B60L 15/00-15/38

Claims (1)

(57) [Claims] 1. A method for monitoring the speed of an electric vehicle in which forward and backward speeds can be changed to a plurality of speeds with different upper limit set speed values. The vehicle is driven by repeatedly inputting the pulse train to which the neutral signal is added to the traveling motor.When the neutral signal is transmitted, the generated voltage induced by the traveling motor is constantly measured to average the vehicle speed. The duty ratio of the drive signal occupying the entire pulse train is controlled so that the average value of the vehicle speeds in each shift speed is within the range not exceeding the upper limit set speed value. When an abnormal speed is detected by comparing with a speed limit value designed slightly higher than each upper limit set speed value of each speed change step, an appropriate emergency stop mechanism is operated. Speed monitoring method of an electric vehicle to symptoms.