JP2008154324A - Braking apparatus of industrial electric drive vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a braking apparatus of industrial electric drive vehicle in which setting and structure are simple, safety is high, and recovery of regenerative energy is high. <P>SOLUTION: The braking apparatus comprises a mechanical hydraulic brake operated by a brake pedal, an inverter for controlling a travelling motor, and a vehicle controller for controlling an inverter based on the detection signal from a brake pedal stepping amount detector. The vehicle controller is arranged to perform braking with a regenerative brake torque ET increasing gradually as the stepping amount increases in a low speed brake zone T between the brake pedal off position 0 to a mechanical brake start point t based on the detection value from the stepping amount detector, and to perform braking with a mechanical brake torque MT and a regenerative brake torque ET increasing gradually as the stepping amount increases in a high speed brake zone OT exceeding the mechanical brake start point t. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a braking device suitable for an industrial electric drive vehicle such as a wheel loader, a forklift, a dump truck, and the like, which particularly has a lot of work traveling in which forward and backward advancement and stop of low-speed rotation are repeated.

In a braking device for a vehicle that uses both a regenerative (electric) brake and a hydraulic (mechanical) brake, the regenerative braking torque and the hydraulic braking torque are distributed according to the depression speed of the brake pedal. For example, Japanese Patent Application Laid-Open No. H10-228667 discloses a control that controls the total braking torque.
JP-A-6-253406

However, in Patent Document 1,
A) The brake pedal depressing speed varies depending on the individual operator. In normal times, the brake pedal is depressed while feeling the reaction force of the brake pedal. Therefore, the brake pedal is often depressed at a stroke until the predetermined reaction force is felt. Setting torque is difficult,
B) Since the stepping speed is calculated and fed back to the hydraulic brake, a hydraulic control circuit for the hydraulic brake and a device for changing the braking force are required, and the structure is complicated.
C) Since the operation of the hydraulic brake involves electric control of the regenerative brake, if a problem occurs in the electric control system, the hydraulic brake cannot be operated, and there are problems such as further safety measures being required. It was.

  The present invention solves the above-mentioned problems, and is an industrial electric drive suitable for an industrial electric drive vehicle that is easy to set and structure, has high safety, and repeats forward / backward movement and stop of low-speed rotation and frequently performs work traveling. An object of the present invention is to provide a braking device for a vehicle.

  According to the first aspect of the present invention, a mechanical hydraulic brake that brakes a traveling wheel by supplying and discharging pressure oil to and from a driving chamber by a brake valve operated by a brake pedal, and a depression amount that detects a depression amount of the brake pedal A detector, an inverter device for controlling the driving motor, and a vehicle controller for controlling the inverter device based on a detection signal of the stepping amount detector, wherein the vehicle controller is set to a detection value of the stepping amount detector. Based on this, the regenerative braking torque is gradually increased in response to an increase in the brake depression amount, and the brake valve is supplied with pressure oil to the drive chamber at the depression amount from the brake pedal off position to the mechanical braking start point. In response to the increase in the amount of stepping from the mechanical braking start point, the supply of pressure oil to the drive chamber is gradually increased to increase the mechanical braking torque. The regenerative braking torque is defined as the total braking torque by the amount of brake depression between the brake pedal off position and the mechanical braking start point, and the regenerative braking torque The total is the total braking torque.

According to a second aspect of the present invention, in the configuration according to the first aspect, the inverter device is provided with a battery for storing regenerative power from the traveling motor.
According to a third aspect of the present invention, in the configuration of the first or second aspect, the vehicle controller performs stop position control for generating a regenerative braking torque that restrains and stops the traveling wheels on the traveling motor, and controls the amount of depression of the accelerator pedal. A slope start changeover switch is provided that performs delay control to give a driving force to the traveling motor when the corresponding driving torque exceeds the regenerative braking torque.

  According to the first aspect of the present invention, since it is not necessary to use the hydraulic brake during traveling, it is possible to greatly reduce the wear of the brake member such as the disc, drum and pad of the hydraulic brake, and to increase the life of the brake member. Can be extended. Furthermore, if regenerative braking is used during high-speed rotation, it is necessary to use large and large-capacity regenerative brake components such as an inverter device, a traveling motor, and a heat dissipation brake resistor. Since only the regenerative braking is used at the time of rotation, and the entire braking torque at the time of high-speed rotation or sudden braking is supplemented by the hydraulic brake, the components of the regenerative brake can be reduced in size. Furthermore, the hydraulic brake is operated by the brake pedal via the brake valve, and is independent of the regenerative brake components and the control electric circuit. Can be braked, easy to set up and structure, and high in safety.

  According to the second aspect of the present invention, at the time of work traveling that repeats forward / backward movement and stop at low speed rotation, the travel motor is braked only by regenerative braking in a low speed braking range from the off position to the mechanical braking start point, By storing the regenerative power collected by this regenerative braking in the accumulator of the inverter device and using it forward and backward, it is possible to collect regenerative energy with high efficiency during work travel and to make effective use of it (when using a hydraulic brake, Energy cannot be recovered effectively).

  According to the third aspect of the present invention, the hill start changeover switch is turned on, and the vehicle controller performs the stop position control to stop the traveling wheel by applying the regenerative brake and regenerative braking, and the driving force is reduced by depressing the accelerator pedal. Since the delay control for delaying the transmission to the traveling wheels is performed, it is possible to smoothly start the slope by operating the slope start switch at the operator's discretion. At this time, since the hydraulic brake is not used, wear of the braking member can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Embodiment 1]
This vehicle is, for example, an electrically driven vehicle such as a wheel loader equipped with a working device (not shown) for rotating and raising / lowering a work tool such as a bucket via a work boom, as shown in FIG. The generator 11 and the hydraulic pump 13 are driven by the engine 11, and the front and rear traveling wheels 14 and the like are driven to rotate by the power of the generator 12, and the working device and the hydraulic brake 16 are driven by the hydraulic pressure of the hydraulic pump 13. It is comprised so that it may do.

  The traveling wheels 14 are each driven to rotate by a traveling motor 15 via a speed reducer, and the traveling motor 15 is driven and controlled by a vehicle controller 31 via an inverter device 32 in FIG. Each traveling wheel 14 is provided with a mechanical hydraulic brake 16 that brakes the axle via a brake member such as a brake disk or a brake pad, and a regenerative brake that is regeneratively braked via an inverter device 32 by a vehicle controller 31. The traveling wheels 14 are braked by the hydraulic brake 16 and the regenerative brake, respectively.

  As shown in FIG. 3, the brake hydraulic circuit 21 that operates the hydraulic brake 16 is operated by a brake accumulator 22 that accumulates the pressure oil supplied by the hydraulic pump 13 and a brake pedal 23 provided in the driver's seat. And a brake valve (flow control valve) 24 for supplying and discharging the pressure oil of the brake accumulator 22 to and from the hydraulic brake 16, and the hydraulic brake 16 is a single-acting cylinder to which pressure oil is supplied and discharged from the brake valve 24. The drive chamber 16a is operated, a single-acting cylinder is operated by the drive chamber 16a, and the brake disc is pressurized via the brake pad to operate the hydraulic brake 16. The single acting cylinder is provided with a restraining spring 16b that discharges the pressure oil from the drive chamber 16a. The brake pedal 23 is provided with a stepping position detector (stepping amount detector) 25 comprising a potentiometer for detecting the stepping amount.

  As shown in FIG. 4, the inverter device 32 that supplies electric power from the generator 12 to the traveling motor 15 includes a reversible converter using two sets of thyristor converters, and includes a converter unit 33, a smoothing circuit unit 34, and an inverter unit. 35, a capacitor (capacitor) 36 for accumulating regenerative power via a rectifier circuit 36a composed of a thyristor and a coil, and a braking resistor with a cooling fan for radiating heat for consuming the regenerative power when the capacitor 36 is overcharged The regenerative electric power at the time of regenerative braking can be stored in the capacitor 36 and used during traveling. Then, the vehicle controller 31 outputs a control signal for controlling the driving drive and the regenerative braking of the traveling motor 15 to the inverter unit 35.

  As shown in FIG. 5, the vehicle controller 31 includes a turning position detector 25, a travel direction switching lever 41 that switches between forward-neutral-reverse and speed modes, an accelerator pedal 42 that performs acceleration / deceleration, and turning. A steering handle 43 for setting, a slope start changeover switch 44 used when starting a slope, a parking brake switch 45 for operating a parking brake provided integrally with the hydraulic brake 16 of each axle, and an engine speed changeover switch 47 and other switches such as operation preparation / cancellation switches are input. The operation output signal of the vehicle controller 31 is output to the inverter unit 35 of the inverter device 32, the engine controller 46, a display lamp, and the like.

The regenerative brake and hydraulic brake 16 of this electrically driven vehicle will be described.
As shown in FIG. 1 (a), when the brake pedal 23 is depressed and the depression position detector 25 increases the brake depression amount from the off position 0 to the mechanical braking start point t within the low speed control region T, the vehicle controller 31 The unit 35 is controlled so that the regenerative braking torque ET is gradually increased in response to an increase in the brake depression amount, the regenerative brake is applied to each traveling motor 15, and the traveling wheel 14 is braked. Within this low speed control region T, the brake valve 24 is held in the closed position and the hydraulic brake 16 is not operated. Next, when the high-speed braking range OT in which the brake depression amount increases from the mechanical braking start point t, the vehicle controller 31 controls the inverter unit 35 to further gradually increase the regenerative braking torque ET corresponding to the increase in the depression amount. A regenerative brake is applied to each motor 15 to brake the traveling wheel 14. At the same time, the brake valve 24 gradually increases and supplies the pressure oil of the brake accumulator 22 to the drive chamber 16a in response to an increase in the brake depression amount, and gradually increases the mechanical braking torque MT of the hydraulic brake 16 to increase the traveling wheel 14. Brake.

  Thus, in the low-speed braking range O where the brake depression amount is from the off position 0 to the mechanical braking start point t, only the regenerative brake is actuated to brake the traveling wheel 14 and the braking depression amount exceeds the mechanical braking start point t. In the range OT, the regenerative brake is activated by the vehicle controller 31 and the hydraulic brake 16 is activated at the same time, and the traveling wheel 14 is braked with a large braking force. Accordingly, the regenerative braking torque ET becomes the total braking torque AT in the low speed braking range T, and when the high speed braking range OT is reached, the mechanical braking torque MT is supplemented in addition to the regenerative braking torque ET, and the regenerative braking torque ET and the mechanical braking torque MT Is the total braking torque AT.

  Here, the mechanical braking start point t is suitably in the range of 0.25 to 0.4 times the maximum total braking torque ATmax at which the brake depression amount is the full stroke. This is because when the maximum brake torque ATmax is less than 0.25 times, the frequency of use of the hydraulic brake 16 is excessive, the wear amount of the brake member is large, and the recovery efficiency of the regenerative energy is low. This is because the number of times of braking at high speed increases and the regenerative braking torque is increased, so that it is necessary to increase the size of the inverter device 32 and the like, which increases the equipment cost. Further, a preferable value of the mechanical braking start point t is in a range of 0.3 to 0.35 times the maximum total braking torque ATmax. In this way, in the low-speed braking region T where the brake depression amount is from the off position 0 to the mechanical braking start point t, the entire braking torque during the operation traveling that repeats forward / reverse and stop at low-speed rotation is performed only by regenerative braking. Is set.

  In addition, an industrial electric drive vehicle is provided with an inching switch that is used to accurately approach an object such as a load by intermittently stopping and moving forward or backward at low speeds (for example, a special feature). Open 2001-245406). In the absence of this inching switch, the brake pedal and accelerator pedal provided on the left and right are operated alternately to move back and forth intermittently. And fuel is consumed at the same time, resulting in a waste of energy. In order to prevent this, the conventional inching switch controls so that the driving force of the travel motor does not act when the brake pedal is operated.

  In the industrial electric drive vehicle of the present invention, the regenerative brake covers the off position 0 of the brake pedal 23 used at low speed to the mechanical braking start point t. Therefore, when the brake pedal 23 and the accelerator pedal 42 are stepped on simultaneously. The brake motor 23 is prioritized and the travel motor 15 is regeneratively braked. When the brake pedal 23 is in the off position 0 and the accelerator pedal 42 is depressed, the travel motor 15 is driven. Even when the brake pedal 23 and the accelerator pedal 42 are alternately depressed, the brake and the traveling motor 15 are not simultaneously operated.

  By the way, in FIGS. 1A and 1B, the rate of change of the total braking torque AT accompanying the change in the brake depression amount is small in the low-speed braking region T, large in the high-speed braking region OT, and low at the mechanical braking start point t. It has become. This is because the operator operates the brake pedal 23 in a normal manner in the low-speed braking region T and operates the brake pedal 23 with such a large pressure that the brake is applied for the first time in the high-speed braking region OT during low-speed traveling including work traveling. Therefore, there is no problem in the operator's sense of operation between the low-speed braking area T and the high-speed braking area OT. Of course, as shown in FIG. 1 (c), the regenerative braking torque ET is controlled as indicated by a virtual line or a broken line, and the total braking torque in the low speed braking area T and the high speed braking area OT according to the change in the brake depression amount. The rate of change of AT can also be made constant.

  Further, for example, Japanese Patent Application Laid-Open No. 7-322404 proposes a technique that allows a vehicle to start without falling down when starting on a slope. In this technique, when the rotational speed and rotation direction of the traveling motor and the traveling direction command by the traveling direction switching lever are opposite, the restraint stop state is automatically set. However, in the above conventional example, the vehicle cannot be lowered by its own weight without intentionally switching the traveling direction switching lever (the position is not automatically stopped). In the present invention, a slope start changeover switch 44 is provided, and the traveling wheel 14 is restrained and stopped when the operator arbitrarily turns it on.

  That is, by turning on this slope start changeover switch 44, the vehicle controller 31 performs stop position control of the traveling wheels 14. A stop command is output from the vehicle controller 31 to the converter unit 33, and based on the rotational direction and rotational speed fed back from the traveling motor 15, regenerative braking torque is generated so that the rotational speed of the traveling motor 15 becomes zero. To restrain the vehicle on the slope. When the accelerator pedal 42 is operated, when the command value of the drive torque output according to the depression amount exceeds the regenerative braking torque, the regenerative brake is released and the traveling wheel 14 is rotationally driven to perform delay control. As a result, the slope starts smoothly. The mechanical braking start point t is a regenerative braking torque ET that stops at a gradient of about 10%. In this stop position control, the regenerative braking torque ET exceeding the mechanical braking start point t is generated and the vehicle is stopped only by the regenerative brake. To do.

  According to the above embodiment, only regenerative braking is performed within the low-speed braking area T where the brake depression amount is from the off position 0 to the mechanical braking start point t, and in the low-speed braking area T, the operation of repeating forward / reverse and stop at low-speed rotation is performed. Driving is performed. As a result, the traveling motor 15 is regeneratively braked, the recovered regenerative power is stored in the capacitor 36 of the inverter device 32, and this regenerative power is used for driving the traveling motor 15 in the forward and backward directions, so that energy can be efficiently generated. It can be recovered and used effectively. If the hydraulic brake 16 is used during work travel, regenerative energy cannot be recovered effectively.

Further, since it is not necessary to use the hydraulic brake 16 in the low-speed braking region T, the wear of the braking member of the hydraulic brake 16 can be greatly reduced, and the life of the braking member can be extended.
Furthermore, when braking is performed only by regenerative braking in the high-speed braking range OT, it is necessary to use a large-sized and large-capacity inverter device 32, travel motor 15, and heat-dissipating braking resistor 37. In the low-speed rotation region T, braking is performed only with the regenerative braking torque ET, and the regenerative braking torque ET is supplemented with the mechanical braking torque MT by the hydraulic brake 16 in the high-speed rotation region OT. There is no need to

  Furthermore, since the stop position control and the delay control are performed by the vehicle controller 31 by the slope start switch 44, the slope of the electrically driven vehicle can be smoothly started at the discretion of the operator at any time. Since it is not used, the wear of the braking member can be reduced.

  In addition, since the brake hydraulic circuit 21 of the hydraulic brake 16 and the electric circuit for controlling the regenerative brake are installed independently of each other, even if a trouble occurs in the electric system, the brake valve 24 is operated by the brake pedal 23. The hydraulic brake 16 can be operated via the vehicle, and the vehicle can be stopped safely.

  FIG. 6 shows a power supply circuit diagram of a traveling motor in another embodiment of the industrial electric drive vehicle, in which the capacitor 36 is omitted. Thereby, it is comprised so that the regenerative electric power by regenerative braking may be consumed by the braking resistor 37 with a cooling fan for thermal radiation. According to this embodiment, the regenerative power cannot be effectively used as compared with the previous embodiment, but other effects can be similarly achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing a relationship between a brake pedal depression amount and a braking torque in an embodiment of a braking device for an industrial electric drive vehicle according to the present invention, in which (a) shows a brake depression amount, a regenerative braking torque, and a machine in a first example; (B) shows the total braking torque of the first example, and (c) shows the relationship between the brake depression amount of the second example, the regenerative braking torque, the mechanical braking torque, and the total braking torque. It is a schematic block diagram of an industrial electric drive vehicle. It is a hydraulic circuit diagram for brakes. It is a power supply circuit diagram of a travel motor. It is a control block diagram of an industrial electric drive vehicle. It is the electric power feeding circuit diagram of the traveling motor which shows other embodiment of an industrial electric drive vehicle.

Explanation of symbols

ET Regenerative braking torque MT Mechanical braking torque AT Total braking torque t Mechanical braking start point T Low speed braking range OT High speed braking range 11 Engine 12 Generator 14 Traveling wheel 15 Traveling motor 16 Hydraulic brake 16a Drive chamber 21 Brake hydraulic circuit 22 Brake accumulator 23 Brake pedal 24 Brake valve 25 Depressed position detector 31 Vehicle controller 32 Inverter device 35 Inverter unit 36 Capacitor (capacitor)
37 Braking resistor 42 Accelerator pedal 44 Slope start changeover switch

Claims (3)

A mechanical hydraulic brake that brakes the traveling wheel by supplying and discharging pressure oil to the drive chamber by a brake valve operated by a brake pedal;
A depression amount detector for detecting the depression amount of the brake pedal;
An inverter device for controlling the driving motor;
A vehicle controller for controlling the inverter device based on a detection signal of the depression amount detector,
The vehicle controller is configured to gradually increase the regenerative braking torque in response to an increase in the brake depression amount based on a detection value of the depression amount detector,
Pressure oil is not supplied to the drive chamber when the brake valve is depressed from the brake pedal off position to the mechanical braking start point, and pressure oil is supplied to the drive chamber in response to an increase in the depression amount from the mechanical braking start point. Is configured to gradually increase the mechanical braking torque,
The regenerative braking torque is the total braking torque based on the brake depression amount between the brake pedal off position and the mechanical braking start point, and the sum of the regenerative braking torque and the mechanical braking torque is the total braking torque when the brake depression amount is greater than or equal to the mechanical braking start point. Industrial electric drive vehicle braking device. The braking device for an industrial electric drive vehicle according to claim 1, wherein the inverter device is provided with a capacitor for storing regenerative electric power from the traveling motor. The vehicle controller performs stop position control for generating regenerative braking torque that restrains and stops the traveling wheels on the traveling motor, and when the driving torque corresponding to the depression amount of the accelerator pedal exceeds the regenerative braking torque, the driving force is applied to the traveling motor. The brake device for an industrial electric drive vehicle according to claim 1 or 2, further comprising a slope start changeover switch for performing a delay control for giving a delay.

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