JP3477749B2 - Travel control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a travel control device, and more particularly to a travel control device for controlling driving or braking of an electric motor. [0002] In recent years, it has been considered to use an induction motor instead of a DC motor in a battery forklift. The induction motor has advantages such as a small change in speed with respect to an increase or decrease in load, a simple structure and robustness, and control of speed, torque and forward / reverse rotation can be easily and reliably performed by slip frequency control. [0003] In a conventional traveling control device for an induction motor based on slip frequency control, as shown in FIG. 8, a DC supplied from a battery 1 as a DC power source is converted into a three-phase AC by an inverter 2 and the three-phase AC is supplied. Drives the three-phase induction motor 3. The drive of the inverter 2 is controlled by a travel control circuit 4, and the control operation of the travel control circuit 4 is performed in the following order. [0004] The traveling control circuit 4 includes an accelerator pedal ACC.
Based on a detection signal from the accelerator sensor 5 that detects the amount of depression of the vehicle, a torque (target torque) that the induction motor 3 desired by the driver to generate is obtained. Further, an open circuit signal of the operation detection switch 5a due to the depression of the accelerator pedal ACC is output to the traveling control circuit 4. The traveling control circuit 4 receives a detection signal output from a rotation sensor 8 for detecting the rotation speed of the induction motor 3, and based on the detection signal, the actual rotation speed of the induction motor 3 (actual rotation speed). Ask for. The traveling control circuit 4 calculates a slip frequency based on the obtained target torque and actual rotation speed. Further, the traveling control circuit 4 obtains the rotation frequency of the induction motor 3 based on the detection signal from the rotation sensor 8. Since the travel control circuit 4 detects the open circuit signal of the operation detection switch 5a, it determines that the vehicle is to travel, and adds the slip frequency and the rotation frequency to obtain a command frequency. The traveling control circuit 4 is operated based on the command frequency.
Controls ON / OFF of each transistor of the inverter 2 to drive and control the induction motor 3. On the other hand, accelerator pedal A
When the depression of the CC is released, a detection signal corresponding to the release is output from the accelerator sensor 5 to the traveling control circuit 4. In addition, a closing signal of the operation detection switch 5a due to the release of the accelerator pedal ACC is output to the traveling control circuit 4. [0008] The traveling control circuit 4 is based on a detection signal from the accelerator sensor 5 and controls the induction motor 3 desired by the driver.
The target torque at which is to be generated is determined. The traveling control circuit 4
A detection signal output from a rotation sensor 8 that detects the rotation speed of the induction motor 3 is input, and the actual rotation speed of the induction motor 3 is obtained based on the detection signal. The travel control circuit 4 calculates a slip frequency based on the obtained target torque and actual rotation speed. Further, the traveling control circuit 4 determines the rotation frequency of the electric motor 3 based on the detection signal from the rotation sensor 8. Since the traveling control circuit 4 detects the closing signal of the operation detection switch 5a, it determines that the vehicle is to be stopped, and subtracts the slip frequency from the rotation frequency to obtain a command frequency. [0010] Based on the command frequency, the travel control circuit 4
Controls ON / OFF of each transistor of the inverter 2 to control the braking of the electric motor 3. By the way, a forklift generally drives a vehicle by depressing an accelerator pedal ACC, and then releases the depression of an accelerator to allow the vehicle to coast. However, in this forklift, when the accelerator pedal ACC is released, the traveling control circuit 4 controls ON / OFF of each transistor of the inverter 2 to control the braking of the induction motor 3, so that the forklift suddenly stops. Therefore, there is a problem that the forklift cannot be coasted by the operation of depressing and releasing the accelerator pedal ACC. Further, there is a case where the cargo handling work is performed by repeatedly repeating the depression and release of the accelerator pedal ACC.
Then, the traveling control circuit 4 performs drive control and braking control of the induction motor 3 at substantially the same timing by rapidly repeating depression and release of the accelerator pedal ACC, so that the forklift vibrates to give an uncomfortable feeling to the worker, There is a problem that collapse occurs. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to enable coasting even if the accelerator pedal is released, and to quickly repeat the depression and release of the accelerator pedal. It is an object of the present invention to provide a travel control device that prevents the vehicle from vibrating even when the vehicle is driven. Means for Solving the Problems [0017] The above-mentioned problems have been solved.
Because, an invention according to claim 1, an electric motor driving the vehicle, and switching means for causing the brake control or drive control of the electric motor, the torque setting operation unit for setting the torque motor should occur, the torque Motor drive control means for controlling the driving of the motor via the switching means based on the operation amount of the setting operation means, and motor braking control means for controlling the braking of the motor via the switching means based on the release of the operation of the torque setting operation means In the travel control device, when the torque setting operation means releases the operation of the torque setting operation means from a state where the operation amount is set within a predetermined range, the electric motor braking is performed. An invalidation area for invalidating the braking control of the electric motor by the control means,
When the torque setting operation means is released from the state in which the operation amount is set in a predetermined range or more of the torque setting operation means, the motor braking control means activates the motor braking control by the motor braking control means. That is the gist. According to the first aspect of the invention, the motor drive control means controls the drive of the motor via the switching means based on the operation of the torque setting operation means. Then, based on the release of the operation of the torque setting operation means, the motor braking control means controls the braking of the electric motor via the switching means. Therefore, based on the operation and release of the torque setting operation means, the vehicle travels by drive control or stops by brake control. When the operation of the torque setting means is released from a state in which the torque setting means has set the operation amount within a predetermined range or more (within the activation area), the braking control of the electric motor is performed. Is done. Further, when the operation of the torque setting means is released from a state in which the torque setting means sets the operation amount within a predetermined range (within the invalidation area), the braking control of the electric motor is not performed. . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIGS. 1 to 4 show a first embodiment in which the present invention is embodied in a travel control device for a battery forklift.
It will be described based on. In this embodiment, the same components as those of the conventional example shown in FIG. 8 are denoted by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 2, a forklift front panel 11 is provided with a brake control disabling switch 12 as disabling setting means. As shown in FIG. 1, the brake control disabling switch 12 is provided between the operation detection switch 5a and the travel control circuit 4 as the motor drive control means and the motor brake control means. The brake control disabling switch 12 can open and close the circuit, and in this embodiment, is normally set to a closed state. When the brake control disabling switch 12 is closed, the traveling control circuit 4 operates as a switching means based on detection signals from the accelerator sensor 5 and the rotation sensor 8 when the accelerator pedal ACC serving as a torque setting operating means is depressed. The drive of the induction motor 3 is controlled via the inverter 2. Also, accelerator pedal ACC
The travel control circuit 4 performs braking control of the induction motor 3 via the inverter 2 based on the detection signal from the accelerator sensor 5 and the detection signal from the rotation sensor 8 by releasing the depression of the vehicle. When the brake control disabling switch 12 is open, the travel control circuit 4 sends the signal via the inverter 2 based on the detection signal from the accelerator sensor 5 and the detection signal from the rotation sensor 8 when the accelerator pedal ACC is depressed. Thus, the drive of the induction motor 3 is controlled. Further, even if the depression of the accelerator pedal ACC is released and the operation detection switch 5a is closed, the brake control disabling switch 12 is open, so that the traveling control circuit 4 determines that the accelerator pedal ACC is depressed. Accordingly, the travel control circuit 4 controls the drive of the induction motor 3 via the inverter 2 based on the detection signal from the accelerator sensor 5 and the detection signal from the rotation sensor 8 at that time. In this case, since the accelerator pedal ACC is not depressed, the detection signal from the accelerator sensor 5 has a minimum value. Accordingly, the travel control circuit 4 is not actually driven by the induction motor 3 via the inverter 2. As a result, the traveling control circuit 4 controls the inverter 2
The braking control of the induction motor 3 is not performed via the control. Therefore, the forklift is coasted by the rotational force of the induction motor 3. Next, the battery constructed as described above
The operation of the travel control device in a forklift will be described. First, the brake control disabling switch 12 on the front panel 11 is operated to bring the circuit into a closed state. As shown in FIG. 3, when the operator depresses the accelerator pedal ACC in this state, a detection signal based on the depression amount from the accelerator sensor 5 and an open signal indicating that the operation detection switch 5a is opened by depressing the accelerator pedal ACC are output. It is input to the travel control circuit 4. The traveling control circuit 4 determines a target torque to be generated in the induction motor 3 based on the detection signal. Further, the traveling control circuit 4 inputs a detection signal output from a rotation sensor 8 for detecting the rotation speed of the induction motor 3, and calculates the actual rotation speed (actual rotation speed) of the induction motor 3 based on the detection signal. Ask. The running control circuit 4 calculates a slip frequency based on the obtained target torque and actual rotation speed. Further, the traveling control circuit 4 obtains the rotation frequency of the induction motor 3 based on the detection signal from the rotation sensor 8. Then, since the operation detection switch 5a is open, the traveling control circuit 4 adds the slip frequency and the rotation frequency to obtain a command frequency. Based on the command frequency, the travel control circuit 4
Controls ON / OFF of each transistor of the inverter 2 to drive and control the induction motor 3. As a result, the drive of the induction motor 3 is controlled in accordance with the depression amount of the accelerator pedal ACC, and the vehicle speed can be adjusted. On the other hand, when the depression of the accelerator pedal ACC is released, the operation detecting switch 5a is closed, and this closing signal is input to the traveling control circuit 4 via the brake control invalidating switch 12. Further, a detection signal corresponding to the release of the depression of the accelerator pedal ACC is output from the accelerator sensor 5 to the traveling control circuit 4. The traveling control circuit 4 determines a target torque desired by the driver to be generated by the electric motor 3 based on the detection signal from the accelerator sensor 5. The traveling control circuit 4 receives a detection signal output from a rotation sensor 8 that detects the rotation speed of the electric motor 3, and obtains the actual rotation speed of the electric motor 3 based on the detection signal. The running control circuit 4 calculates a slip frequency based on the obtained target torque and actual rotation speed. Further, the traveling control circuit 4 determines the rotation frequency of the electric motor 3 based on the detection signal from the rotation sensor 8. Then, since the operation detection switch 5a is closed, the traveling control circuit 4 subtracts the slip frequency from the rotation frequency to obtain a command frequency. Based on the command frequency, the traveling control circuit 4
Controls ON / OFF of each transistor of the inverter 2 to control the braking of the electric motor 3. As a result, the accelerator pedal A
By releasing the depression of the CC, the induction motor 3 is brake-controlled, so that the vehicle speed can be rapidly reduced and stopped immediately. Here, the brake control disabling switch 12 is operated on the front panel 11 so as to be in an open state. As shown in FIG. 4, in this state, the operator operates the accelerator pedal A
If you step on CC, the accelerator pedal ACC
The drive speed of the induction motor 3 is controlled in accordance with the amount of depression of the vehicle to adjust the vehicle speed. On the other hand, when the depression of the accelerator pedal ACC is released, the operation detection switch 5a is closed. However, this closing signal is not input to the traveling control circuit 4 because the brake control invalidating switch 12 is open. Therefore, the travel control circuit 4 does not detect that the depression of the accelerator pedal ACC is released. That is, the travel control circuit 4 is operated by the accelerator pedal A
It is determined that CC has been depressed. Accordingly, the travel control circuit 4 controls the drive of the induction motor 3 via the inverter 2 based on the detection signal from the accelerator sensor 5 and the detection signal from the rotation sensor 8 at that time. In this case, since the accelerator pedal ACC is not depressed, the detection signal from the accelerator sensor 5 has a minimum value. Therefore, when the depression of the accelerator pedal ACC is actually released, the travel control circuit 4 does not control the braking of the induction motor 3 via the inverter 2. Therefore, the forklift can coast by the rotational force of the induction motor 3 so that the vehicle speed is not suddenly reduced. As a result, if the brake control disabling switch 12 is opened, the vehicle can coast by releasing the depression of the accelerator pedal ACC. Accordingly, with a simple configuration in which the brake control disabling switch 12 is provided between the operation detection switch 5a for detecting the depression of the accelerator pedal ACC and the traveling control circuit 4, even if the depression of the accelerator pedal ACC is released. The vehicle can be coasted by not performing the braking control. If the brake control disabling switch 12 is kept open, the brake control of the induction motor 3 is not performed when the accelerator pedal ACC is depressed, so that the accelerator pedal ACC is depressed and released. The vehicle does not vibrate even if it is repeated quickly. As a result, it is possible to prevent the operator from feeling uncomfortable and to prevent the load held by the forklift from collapsing. In this embodiment, the accelerator pedal AC
When the depression of C is released, the operation detection switch 5a
Is closed, but the operation detection switch 5a may be opened when the depression of the accelerator pedal ACC is released. In this case, the brake control invalidation switch 12 is connected in parallel with the operation detection switch 5a, and the brake control is invalidated when the invalidation switch 12 is closed. In this embodiment, the operation detecting switch 5a and the brake control invalidating switch 12 are connected in series. In addition, the brake control invalidation switch 12 is provided independently for the travel control circuit 4. When the brake control disabling switch 12 is opened, the accelerator pedal ACC
The drive control and the brake control are performed based on the opening and closing of the operation detection switch 5a by the depression and release of the operation. Further, when the brake control disabling switch 12 is closed, only the drive control can be performed based on the opening and closing of the operation detection switch 5a by depressing and releasing the accelerator pedal ACC. [Second Embodiment] In the first embodiment, the travel control device for disabling the braking control of the three-phase induction motor 3 has been embodied. Next, the travel control device for disabling the braking control of the DC motor will be described. A second embodiment of the present invention will be described. still,
The same members as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. As shown in FIG. 5, a DC motor 23 comprising an armature 21 and a field winding 22 is provided with a forward contactor 24 as switching means and a reverse contactor 25 as switching means. ing. The forward and reverse contactors 24 and 25 are switched and connected by the travel control circuit 4, and set to the forward mode or the reverse mode.
The traveling control traveling 4 controls the switching of the transistor 26 and drives and controls the DC motor 23. Therefore, when the brake control disabling switch 12 is closed, the traveling control circuit 4 controls the forward and reverse contactors 24 based on the detection signal from the depression of the accelerator sensor 5 and the opening signal from the operation detection switch 5a. , 25 are controlled to perform forward traveling or reverse traveling. When the accelerator pedal ACC is released, the travel control circuit 4 switches the forward and reverse contactors 24 and 25 to perform reverse-phase braking control and immediately stops the vehicle. When the brake control disabling switch 12 is open, the traveling control circuit 4 controls the forward and reverse contactors 2 based on the detection signal from the depression of the accelerator sensor 5 and the opening signal from the operation detection switch 5a.
4, 25 are switched to perform forward traveling or reverse traveling. Further, even if the accelerator pedal ACC is released, the travel control circuit 4 does not control the switching of the forward and reverse contactors 24 and 25. That is, the anti-phase braking control is not performed. As a result, coasting of the vehicle can be enabled. Third Embodiment Next, a third embodiment of the present invention will be described. In the third embodiment, the functions described below are added to the accelerator pedal ACC of the first and second embodiments. The third embodiment will be described based on the first embodiment. As shown in FIG. 6, the accelerator pedal ACC
, An invalidation area and an activation area based on the amount of depression are set. That is, a region from the state where the accelerator pedal ACC is not depressed to the depression amount θ1 is set as an invalidation region, and a region from the depression amounts θ1 to θ2 is set as an activation region. The accelerator sensor 5 detects the amount of depression of the accelerator pedal ACC, and outputs a detection signal to the travel control circuit 4. The traveling control circuit 4 determines whether the accelerator pedal ACC is located in the invalidation area or the activation area based on the detection signal from the accelerator sensor 5. When the accelerator pedal ACC is depressed in a state where the operation detection switch 5a is closed, that is, in a state where the brake control invalidating switch 12 is not set, the first embodiment is based on the depression amount. Similarly, the traveling control circuit 4 controls the drive of the induction motor 3 via the inverter 2. When the depression of the accelerator pedal ACC is released, a closing signal is input from the operation detection switch 5a of the accelerator sensor 5 to the travel control circuit 4. Then, the travel control circuit 4 determines in which region the accelerator pedal ACC was located before the closing signal from the operation detection switch 5a is input to the travel control circuit 4 based on the detection signal from the accelerator sensor 5. It is supposed to. That is, the depression amount of the accelerator pedal ACC is
Depress the accelerator pedal ACC and operate the operation detection switch 5.
The signal from the accelerator sensor 5 is stored in the travel control circuit 4 until the accelerator pedal ACC is released after the signal a changes to the open circuit signal and the operation detection switch 5a changes to the close signal. Among them, the maximum value is determined as the depression amount of the accelerator pedal ACC. When the travel control circuit 4 determines that the depression amount of the accelerator pedal ACC is within the effective range of θ1 to θ2 based on the detection signal from the accelerator sensor 5,
The traveling control circuit 4 controls the braking of the induction motor 3 via the inverter 2 based on the release of the depression of the accelerator pedal ACC. When the travel control circuit 4 determines that the depression amount of the accelerator pedal ACC is within the invalid range of 0 to θ1 based on the detection signal from the accelerator sensor 5, the travel control circuit 4 determines Even when the depression is released, the braking control of the induction motor 3 is not performed via the inverter 2. Therefore, the accelerator pedal A
When the depression amount of the CC is operated within the range of 0 to θ1, the travel control circuit 4 does not perform the braking control of the induction motor 3. Next, the operation of the traveling control device configured as described above will be described with reference to the flowchart shown in FIG. First, the brake control disabling switch 12 on the front panel 11 is operated to bring the circuit into a closed state. In this state, the travel control circuit 4 determines whether or not the accelerator pedal ACC is depressed based on the operation detection switch 5a of the accelerator sensor 5 (STEP1, hereinafter, STEP is simply referred to as S). When the opening signal from the operation detection switch 5a is not input to the traveling control circuit 4, the traveling control circuit 4 waits until the opening signal of the operation detection switch 5a is input. When the accelerator pedal ACC is depressed, an open circuit signal from the operation detection switch 5a and a detection signal from the accelerator sensor 5 are input to the travel control circuit 4. Then, the traveling control circuit 4 sets the accelerator pedal ACC
The drive of the induction motor 3 is controlled via the inverter 2 in the same manner as in the first embodiment (S2). The traveling control circuit 4 determines whether or not the depression of the accelerator pedal ACC has been released based on the operation detection switch 5a (S3). And the accelerator pedal A
When the CC is continuously depressed, an open circuit signal is input to the travel control circuit 4 from the operation detection switch 5a. Therefore, the travel control circuit 4 returns to STEP 2 again, and controls the drive of the induction motor 3 via the inverter 2 based on the depression amount of the accelerator pedal ACC. When a closing signal is input from the operation detection switch 5a to the travel control circuit 4, the travel control circuit 4
Determines that the accelerator pedal ACC has been released. Then, the traveling control circuit 4 sets the accelerator pedal A before the closing signal is input from the operation detection switch 5a.
It is determined based on the detection signal from the accelerator sensor 5 whether the CC is located in the invalidation area or the activation area (S4). Before the depression of the accelerator pedal ACC is released based on the detection signal from the accelerator sensor 5, the travel control circuit 4 determines that the depression amount of the accelerator pedal ACC is θ1.
When it is determined that the vehicle is located between .theta.2 and .theta.2, the travel control circuit 4 controls the braking of the induction motor 3 via the inverter 2 as in the first embodiment (S5). On the other hand, the traveling control circuit 4 includes an accelerator sensor 5
Before the depression of the accelerator pedal ACC is released based on the detection signal from the controller, when it is determined that the depression amount of the accelerator pedal ACC is located between 0 and θ1, the travel control circuit 4 executes the first embodiment. As in the example, the braking control of the induction motor 3 is not performed. (S6). Therefore, the accelerator pedal ACC is set to 0 to θ1.
The brake control of the induction motor 3 is not performed even if the brake pedal is repeatedly depressed. As a result, there is no shock when the accelerator pedal ACC is lightly depressed to control the forklift at a very low speed, and it is possible to prevent the body from shaking and the load of the fork from collapsing due to the shaking. Note that the ranges of the invalidation region and the activation region of the accelerator pedal ACC may be changed as necessary. Further, when the depression of the accelerator pedal ACC is released from the state where the accelerator pedal ACC is located in the invalidation region, the braking control of the induction motor 3 is not performed, but the braking of the induction motor 3 is reduced. It is also possible to set as follows. In the first to third embodiments, the torque setting means is embodied as the accelerator pedal ACC. However, the braking control of the electric motor is performed based on the operation amount of the operation lever or the like, or the braking control is invalidated. Such a configuration is also possible. As described in detail above, according to the present invention, coasting is enabled even when the accelerator pedal is released, and even if the accelerator pedal is repeatedly depressed and released. There is an excellent effect that the vehicle does not vibrate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an electric circuit diagram of a traveling control device according to a first embodiment of the present invention. FIG. 2 is a partial perspective view showing that a brake control disabling switch is provided on a front panel. FIG. 3 is an explanatory diagram showing that drive control and braking control are performed based on depression and release of an accelerator pedal. FIG. 4 is an explanatory diagram showing that the braking control of the induction motor is not performed even if the depression of the accelerator pedal is released by setting the brake control disabling switch. FIG. 5 is an electric circuit diagram showing a second embodiment of the travel control device applied to the DC motor. FIG. 6 is an explanatory diagram showing that braking control of an induction motor is enabled or disabled depending on the amount of depression of an accelerator pedal. FIG. 7 is a flowchart illustrating that drive control or braking control of the induction motor is performed based on the depression amount of the accelerator pedal. FIG. 8 is an electric circuit diagram of a conventional traveling control device. [Description of Signs] 2 ... Inverter as switching means, 3 ... Induction motor, 4
... A traveling control circuit as electric motor drive control means and electric motor braking control means, 12... A braking invalidation switch as invalidation setting means, and ACC an accelerator pedal as torque setting operation means.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-50-158018 (JP, A) JP-A-2-269401 (JP, A) JP-A-56-58703 (JP, A) JP-A 47-158 44711 (JP, A) JP-A-1-136502 (JP, A) JP-A-64-34103 (JP, A) JP-A-3-21904 (JP, U) JP-A-59-50506 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B60L 15/20 H02P 5/41

Claims (1)

(57) [Claim 1] An electric motor for driving a vehicle, switching means for performing braking control or drive control of the electric motor, and torque setting operation means for setting a torque to be generated by the electric motor. An electric motor drive control means for controlling the driving of the electric motor via a switching means based on the operation amount of the torque setting operation means; and a braking control of the electric motor via the switching means based on the release of the operation of the torque setting operation means. In a travel control device including an electric motor braking control unit, the torque setting operation unit includes the torque setting operation unit.
From the state where the manipulated variable is set within the predetermined range,
When the operation of the lock setting operation means is released, the motor braking
Invalidation area for invalidating the braking control of the motor by the control means
Range and torque setting operation means
Operate the torque setting operation unit from the state where the operation amount is set.
When released, the motor braking control means
A travel control device comprising: an activation region that activates braking control .