JP2002101501A - Brake-control device for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a reduction control and a stop control in a brake-control device without using a mechanical brake, and to simplify the structure of the device as well as to cut down costs. SOLUTION: A vehicle speed detecting unit 21, an accelerator pedal detecting unit 22 and a brake pedal detecting unit 23 are mounted to a brake-control device. Output signals from these detecting units 21 to 23 are output to a control means 25, and a regenerative brake control for a motor 3 on working is performed so as to develop a braking torque corresponding to the difference ΔV between a detected vehicle speed Vd and a command speed Vs when the command speed Vs based on the degree of depressing of an accelerator pedal is lower than the detected vehicle speed Vd detected by the vehicle speed detecting unit 21. Also an electromagnetic brake 29 works by a control of the control means 25 when a main contactor 11 is in an OFF state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking control device for an electric vehicle that uses a traveling motor driven by the output of a battery as a power source.

[0002]

2. Description of the Related Art There is a battery forklift as an electric vehicle having a battery mounted thereon and driven by a traveling motor driven by the output of the battery, and is, for example, configured as shown in FIGS.

FIG. 4 shows an external structure of a counterbalance type forklift, in which a battery 2 mounted on a vehicle body 1 is mounted.
To drive the traveling motor 3 to drive the vehicle, and a directional lever (or switch) for setting the transmission means (not shown) for transmitting the driving force of the traveling motor 3 to one of forward and backward or a neutral state. By the operation of 4), the transmission means is switched between the forward and backward traveling directions and the neutral state, and the steering is performed by the steering wheel 5.
In FIG. 4, reference numeral 6 denotes a mast provided on a front portion of the vehicle body 1, reference numeral 7 denotes a lift bracket provided on the mast 6,
8 is a pair of forks provided on the lift bracket 7,
9 is an accelerator pedal.

Here, the traveling motor 3 is constituted by a three-phase motor such as an induction motor or a DC brushless motor. As shown in FIG. 5, when the main contactor 11, which is a power switch, is turned on, the output DC power of the battery 2 is smoothed by the smoothing capacitor 12, and the six field effect transistors T1 to T6 are connected in full bridge. The driving motor 3 is converted into AC power by the three-phase bridge inverter 13 under chopper control.
The power is supplied to. Each of the field effect transistors T1 to T6 is turned on and off by a control signal from control means such as a microcomputer (not shown).

By the way, in such a forklift, as a configuration relating to braking, in addition to a brake pedal and a mechanical brake (comprising a brake drum, a disk pad, etc.) omitted in FIG. 4, a side brake or a brake pedal is used. There is a deadman brake that brakes when you release your foot.

[0006] Then, a mechanical brake is operated by an operation of a brake pedal by an operator to perform deceleration control during traveling, and a stop control to park and stop the vehicle body 1 by operating a side brake is performed. At this time, weak braking by loosening the depression of the accelerator pedal 9 is also used, but most of the braking by the mechanical brake described above. Further, in the stop control, the parking / stopping state is maintained by continuously depressing the brake pedal to the full.

[0007]

However, in the case of the above-mentioned conventional forklift, both the deceleration control by operating the foot brake and the stop control by operating the side brake operate by applying a mechanical brake to apply the braking. In order to operate the same mechanical brake, there is a problem that a redundant configuration is required, which leads to an increase in cost.

Further, for example, when the vehicle is parked and stopped on an inclined road surface, if the user forgets to operate the side brake, the vehicle body 1 may run away.

Accordingly, an object of the present invention is to enable deceleration control and stop control without using a mechanical brake, thereby simplifying the configuration and reducing costs.

[0010]

To achieve the above object, the present invention utilizes a traveling motor driven by the output of a battery mounted on a vehicle body and a braking torque of regenerative braking of the motor. A deceleration control unit that performs deceleration control by using an electromagnetic brake; a power switch that turns on and off power supply from the battery to the motor; and an electromagnetic brake control unit that operates the electromagnetic brake when the power switch is turned off. It is characterized by having.

According to such a configuration, deceleration control using the braking torque of the regenerative braking of the traveling motor by the deceleration control unit and stop control by the operation of the electromagnetic brake when the power switch is turned off by the electromagnetic brake control unit are performed. Since it can be performed, a mechanical brake as in the related art is not required, so that the configuration can be simplified and the cost can be reduced.

Further, the present invention is characterized in that the electromagnetic brake control unit activates the electromagnetic brake when the accelerator is not operated and the stop state continues for a predetermined time or more.

According to such a configuration, the stop control is performed on condition that there is no operation of the accelerator and the stop state continues for a certain period of time or more, so that the vehicle can be parked and stopped by reliable stop control. .

Further, the invention is characterized in that the electromagnetic brake control section activates the electromagnetic brake even when an emergency stop switch is operated during driving by the motor. According to such a configuration, an emergency stop can be performed in an emergency, and safety can be improved.

Further, the present invention comprises a vehicle speed detecting section for detecting a vehicle speed, and an accelerator detecting section for detecting an operation amount of an accelerator, wherein the deceleration control section detects the accelerator speed more than the vehicle speed detected by the vehicle speed detecting section. When the command speed based on the operation amount of the accelerator by the unit is small, deceleration control by regenerative braking of the motor is performed to generate a braking torque according to the difference between the detected vehicle speed and the command speed.

According to such a configuration, when the command speed based on the accelerator operation amount is smaller than the detected vehicle speed,
Since it can be determined that the operator has released the accelerator, deceleration in accordance with the operator's intention can be performed by performing deceleration control in the same manner as engine braking in an automobile.

Further, the present invention comprises a brake and a brake detector for detecting an operation amount of the brake, and the deceleration controller generates a braking torque corresponding to the operation amount of the brake detected by the brake detector. It is characterized in that deceleration control by regenerative braking of the motor is performed as much as possible.

According to such a configuration, the braking torque by the regenerative braking of the motor can be generated in accordance with the operation amount of the brake detected by the brake detection unit. You can operate the brakes with the same feeling as operating the brakes without any discomfort.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a counterbalance type forklift as an electric vehicle will be described with reference to FIGS. However,
FIG. 1 is a block diagram, FIG. 2 is a partial schematic configuration diagram, and FIG. 3 is an operation explanatory diagram. In FIGS. 1 and 2, the same reference numerals as those in FIGS. 4 and 5 denote the same or corresponding components.

As shown in FIG. 1, a vehicle speed detecting section 21 comprising a wheel speed sensor or the like for outputting a signal corresponding to the vehicle speed, an accelerator pedal detecting section 22 for outputting a signal corresponding to the depression amount of the accelerator pedal 9, and A brake pedal detection unit 23 that outputs a signal corresponding to the amount of depression of the brake pedal is provided. Output signals of these detection units 21 to 23 are output to control means 25 including a microcomputer or the like.
The control unit 25 detects the vehicle speed, the amount of depression of the accelerator pedal 9, and the amount of depression of the brake pedal.

As shown in FIG. 1, an emergency stop switch 27 is provided. When the emergency stop switch 27 is operated, an operation signal from the emergency stop switch 27 is output to the control means 25 and the inverter 13 The control by the control means 25 is performed so as to stop the operation of each part including the stop of the operation.

The control means 25 determines whether or not the command speed Vs based on the amount of depression of the accelerator pedal 9 is smaller than the detected vehicle speed Vd detected by the vehicle speed detector 21. Is also small (Vs
When it can be determined that <Vd), the regenerative braking control of the traveling motor 3 is performed so as to generate a braking torque according to a difference ΔV (= Vd−Vs) between the detected vehicle speed Vd and the command speed Vs.

At this time, for example, as shown in FIG. 3A, a difference ΔV (= Vd−V) between the detected vehicle speed Vd and the command speed Vs.
Vs) and the braking torque corresponding to the difference ΔV are determined, and the braking torque for each numerical value of the speed difference ΔV is tabulated and stored in advance in a memory such as a ROM. When a difference ΔV between the detected vehicle speed Vd and the command speed Vs is generated by the operation, the braking torque corresponding to the difference is read from the memory, and the control unit 25 controls the inverter 1 so that the read braking torque is generated.
3, the regenerative braking control of the traveling motor 3 may be performed.

Thus, the command speed Vs is equal to the detected vehicle speed Vd.
If it is smaller, it can be determined that the operator has depressed the accelerator pedal 9, so that deceleration control similar to engine braking in a gasoline-powered vehicle can be performed.

Further, the control means 25 controls the inverter 13 so as to generate a braking torque corresponding to the operation amount of the brake pedal (the amount of depression of the brake pedal) detected by the brake pedal detection section 23, and Perform regenerative braking control. The regenerative braking control of the traveling motor 3 by the control unit 25 is deceleration control, and the deceleration control process by the control unit 25 corresponds to a deceleration control unit.

At this time, the relationship between the brake depression amount and the braking torque to be generated, as shown in FIG. 3B, for example, is calculated and stored in a table in advance in a memory. The control means 25 controls the inverter 13 so as to generate the read braking torque by reading a braking torque corresponding to the brake depression amount detected by the brake depression amount from the memory.
May be performed.

By the way, as shown in FIG. 1, an electromagnetic brake 29 is provided, and under the control of the control means 25, while the main contactor 11, which is a power switch, is turned on.
The electromagnetic brake 29 is not actuated and the main contactor 11
Is turned off, the electromagnetic brake 29 is operated. Here, as shown in FIG. 2, for example, the rotation of the rotating shaft 31 of the traveling motor 3 is reduced by the
5, it is desirable that the electromagnetic brake 29 is directly connected to the rotation shaft 31 of the traveling motor 3 and locks the rotation shaft 31 of the traveling motor 3 to stop its rotation.
This makes it possible to make the electromagnetic brake 29 compact. The electromagnetic brake 29 may be provided between the traveling motor 3 and the speed reducer 33.

When there is no operation of the accelerator pedal 9 and the stop state continues for a predetermined time or more, the electromagnetic brake 29 is operated by the control means 25,
In addition, when the emergency stop switch 27 is operated during traveling by driving the traveling motor 3, the control means 2
5, the electromagnetic brake 29 is operated. Such control of the electromagnetic brake 29 by the control means 25 is stop control, and the stop control processing by the control means 25 corresponds to an electromagnetic brake control unit.

Therefore, according to the above-described embodiment, the deceleration control using the regenerative braking torque of the traveling motor 3
In addition, since the stop control by the operation of the electromagnetic brake 29 when the main contactor 11 is off is performed,
It is no longer necessary to provide a mechanical brake which is also used for a conventional side brake, so that the configuration can be simplified and the cost can be reduced.

In addition, when the main contactor 11 is turned off, the electromagnetic brake 29 is automatically operated, so that it is possible to improve safety without forgetting to apply the side brake as in the related art.

Further, the stop control is performed on condition that there is no operation of the accelerator pedal 9 and the stop state continues for a predetermined time or more, so that the vehicle is parked and stopped only when it can be determined that the vehicle body 1 has stopped. The vehicle can be securely parked and stopped.

Further, since the electromagnetic brake 29 is operated even when the emergency stop switch 27 is operated, an emergency stop in an emergency is possible, and safety can be further improved.

When the command speed Vs based on the operation amount of the accelerator pedal 9 is smaller than the detected vehicle speed Vd, it can be determined that the operator has depressed the accelerator pedal.
It is possible to reduce the speed in accordance with the intention of the operator. In addition, since the braking torque is generated by the regenerative braking of the traveling motor 3 according to the amount of brake depression, even without a mechanical brake, the operator can operate the brake with the same sensation as operating a normal brake pedal. Can be.

In the above embodiment, the case where the emergency stop switch 27 is provided and the electromagnetic brake 29 is operated even when the emergency stop switch 27 is operated has been described. No need to provide.

In the above embodiment, the brake pedal is provided to generate the braking torque by the regenerative braking of the traveling motor 3 according to the operation amount. However, the brake pedal may not be provided. Needless to say, in this case, the operation of the brake pedal becomes unnecessary, and the burden on the operator can be reduced. In addition, to facilitate starting on a slope, the electromagnetic brake can be forcibly operated by another operation switch, etc., and at the same time, the accelerator can be depressed and the electromagnetic brake can be turned off when the driving force of the motor increases. is there.

Further, in the above-described embodiment, the case where the present invention is applied to the counterbalance type forklift has been described. However, the applicable range of the present invention is not limited to this, and other battery forklifts and electric The vehicle may be an electric vehicle provided with a motor driven by a regenerative braking battery as a driving source.

The present invention is not limited to the above-described embodiment, and various changes other than those described above can be made without departing from the gist of the present invention.

[0038]

As described above, according to the first aspect of the present invention, the deceleration control using the braking torque of the regenerative braking of the traveling motor by the deceleration control unit, and the turning off of the power switch by the electromagnetic brake control unit. Since the stop control by the operation of the electromagnetic brake at the time can be performed, a mechanical brake as in the related art is not required, and the configuration can be simplified and the cost can be reduced.

Further, the electromagnetic brake is automatically activated when the power switch is turned off, so that it is possible to improve safety without forgetting to apply the side brake during parking as in the prior art.

According to the second aspect of the present invention, the stop control is performed on condition that the accelerator pedal is not operated and the stop state continues for a certain period of time or more. It will be possible to stop.

According to the third aspect of the present invention, since the electromagnetic brake is operated even when the emergency stop switch is operated, an emergency stop in an emergency is possible, and safety can be improved. Become.

According to the fourth aspect of the invention, when the command speed based on the operation amount of the accelerator pedal is smaller than the detected vehicle speed, it can be determined that the operator has depressed the accelerator pedal. By performing the deceleration control in the same manner as the brake, it is possible to perform the deceleration that matches the intention of the operator.

According to the fifth aspect of the present invention, the braking torque is generated by the regenerative braking of the motor in accordance with the operation amount of the brake pedal detected by the brake pedal detection unit. Even without
The operator can operate the brake without feeling uncomfortable with the same feeling as operating a normal brake pedal.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a partial schematic configuration diagram according to an embodiment of the present invention.

FIG. 3 is an operation explanatory diagram of one embodiment of the present invention.

FIG. 4 is a side view illustrating a schematic configuration of a general counterbalance type forklift.

FIG. 5 is a partial connection diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle main body 2 Battery 3 Traveling motor 9 Accelerator 11 Main contactor 21 Vehicle speed detecting part 22 Accelerator pedal detecting part 23 Brake pedal detecting part 25 Control means (deceleration control part, electromagnetic brake control part) 27 Emergency stop switch 29 Electromagnetic brake

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D046 AA06 BB01 BB02 BB12 BB17 CC06 HH00 HH02 HH05 HH22 JJ05 KK11 3F333 AA02 AB13 AE02 CA09 CA11 CA21 DA10 DB07 DB10 FA18 FA32 FD20 5H115 PA00 PA01 PA08 PC06 PI06 PO05 PU09 PV09 QE01 QE10 QE12 QH05 QI04 QI07 QN03 TB01 TO21 TO23 UI13 UI23

Claims (5)

[Claims] 1. A traveling motor driven by an output of a battery mounted on a vehicle body, a deceleration control unit that performs deceleration control using a braking torque of regenerative braking of the motor, an electromagnetic brake, and: A brake control device for an electric vehicle, comprising: a power switch for turning on and off the power supply to the motor; and an electromagnetic brake control unit that operates the electromagnetic brake when the power switch is turned off. 2. The electromagnetic brake control unit according to claim 1, wherein the electromagnetic brake control unit activates the electromagnetic brake when the accelerator is not operated and the stop state continues for a predetermined time or more. Electric vehicle braking control device. 3. The brake for an electric vehicle according to claim 1, wherein the electromagnetic brake control unit activates the electromagnetic brake even when an emergency stop switch is operated during traveling by driving the motor. Control device. 4. A vehicle speed detecting section for detecting a vehicle speed, and an accelerator detecting section for detecting an operation amount of an accelerator, wherein the deceleration control section detects an acceleration of the accelerator by the accelerator detecting section more than a vehicle speed detected by the vehicle speed detecting section. 4. A deceleration control by regenerative braking of the motor to generate a braking torque according to a difference between the detected vehicle speed and the command speed when a command speed based on an operation amount is small. The braking control device for an electric vehicle according to any one of the above. 5. A brake and a brake detector for detecting an operation amount of the brake, wherein the deceleration controller is configured to generate a braking torque corresponding to the operation amount of the brake detected by the brake detector. The braking control device for an electric vehicle according to any one of claims 1 to 4, wherein deceleration control is performed by regenerative braking.