JP7425974B2 - Braking control device for industrial vehicles - Google Patents

Description

The present invention relates to a brake control device for an industrial vehicle.

BACKGROUND ART Conventionally, as a technology related to a brake control device for an industrial vehicle, a technology described in, for example, Patent Document 1 is known. Patent Document 1 discloses a hydraulic system that drives a brake by supplying hydraulic oil to a wheel cylinder at a target hydraulic pressure corresponding to a depression stroke of a brake pedal.

Japanese Patent Application Publication No. 2005-297591

In the above conventional technology, in order to quickly reduce the physical gap that causes a delay in the response of mechanical braking force (for example, the gap between the shoe and the inner surface of the drum in a drum brake), the wheel cylinder immediately after the brake pedal is depressed is Brake responsiveness is improved by performing fast-fill control, which increases the hydraulic pressure of the brake pedal to a level higher than the target hydraulic pressure depending on the amount of depression of the brake pedal. However, since the fast fill control starts after the brake pedal is depressed, it is difficult to eliminate the response delay of a certain period of time from when the brake pedal is depressed until the hydraulic pressure rises.

Incidentally, attempts have been made to configure industrial vehicles (e.g. towing tractors, forklifts, etc.), which are equipped with a driving motor that generates regenerative braking force and a mechanical brake that generates mechanical braking force as a braking unit, as electric vehicles that can operate automatically. . In such industrial vehicles, when the industrial vehicle is automatically stopped at a predetermined target stop position, the industrial vehicle is generally decelerated by regenerative braking force, and when the industrial vehicle reaches the target stop position, it is stopped by mechanical braking force. is possible. Here, with regard to the responsiveness of the mechanical braking force at the target stop position, even if measures such as those in the above-mentioned prior art are taken, there is still a response delay, so more effective measures are desired.

SUMMARY OF THE INVENTION An object of the present invention is to provide a braking control device for an industrial vehicle that can reduce the response delay of mechanical braking force when stopping an industrial vehicle at a target stop position using a mechanical brake operated by fluid pressure. do.

A braking control device for an industrial vehicle according to one aspect of the present invention includes, as a braking unit, a travel motor that generates a regenerative braking force and a mechanical brake that is operated by fluid pressure to generate a mechanical braking force. a vehicle speed information acquisition unit that acquires vehicle speed information of the industrial vehicle; a position information acquisition unit that acquires position information of the industrial vehicle; and a vehicle speed information acquisition unit that acquires vehicle speed information of the industrial vehicle; an automatic driving control unit that executes pre-stop braking to bring the industrial vehicle to a stop automatically; Activate.

In the braking control device for an industrial vehicle according to one aspect of the present invention, a mechanical brake is activated when the vehicle speed of the industrial vehicle becomes equal to or less than a predetermined vehicle speed threshold during pre-stop braking. This reduces the physical gap that causes a delay in the response of the mechanical braking force in the mechanical brake. As a result, the mechanical brake is in a state where the response delay of the mechanical braking force is reduced compared to the case where the mechanical brake is not activated. Therefore, according to the braking control device for an industrial vehicle according to one aspect of the present invention, it is possible to reduce the response delay of mechanical braking force when stopping an industrial vehicle at a target stop position using a mechanical brake operated by fluid pressure. becomes.

In one embodiment, the deceleration of the industrial vehicle when the vehicle speed of the industrial vehicle becomes equal to or less than the vehicle speed threshold during pre-stop braking is greater than the deceleration when the vehicle speed of the industrial vehicle is greater than the vehicle speed threshold during the pre-stop braking. It can be small. In this case, compared to the case where the vehicle speed exceeds the vehicle speed threshold, the speed change when the industrial vehicle approaches the target stopping position at a vehicle speed below the vehicle speed threshold is gradual, so the industrial vehicle can be stopped appropriately at the target stopping position. It becomes easier to do so.

In one embodiment, when the vehicle speed of the industrial vehicle becomes equal to or less than a vehicle speed threshold during pre-stop braking, the automatic driving control unit controls the vehicle speed of the industrial vehicle to become the target vehicle speed until the position of the industrial vehicle reaches the target stop position. Alternatively, the mechanical brake may be activated and the travel motor may be powered. In this case, by driving the industrial vehicle at the target vehicle speed and bringing it closer to the target stop position, it is possible to stabilize the accuracy of the stop position of the industrial vehicle with respect to the target stop position.

In one embodiment, the automatic driving control unit may perform regenerative-priority braking that uses the regenerative braking force of the travel motor as the main component when the vehicle speed of the industrial vehicle exceeds a vehicle speed threshold during pre-stop braking. In this case, during regeneration-priority braking, the mechanical brake is likely to be in a state where there is a delay in the response of the mechanical braking force due to the above-mentioned physical gap. Therefore, the effect of reducing the response delay of the mechanical braking force becomes significant.

In one embodiment, when the vehicle speed of the industrial vehicle becomes equal to or less than a vehicle speed threshold during pre-stop braking, the automatic driving control unit operates the mechanical brake by setting the fluid pressure to the first pressure, and the position of the industrial vehicle is adjusted. When the target stop position is reached, stop braking may be performed by setting the fluid pressure to a second pressure that is higher than the first pressure. In this case, stop braking and pre-stop braking can be performed with a simple configuration in which the fluid pressure is set to the first pressure or the second pressure.

According to the present invention, it is possible to reduce the response delay of mechanical braking force when stopping an industrial vehicle at a target stop position using a mechanical brake operated by fluid pressure.

1 is a schematic configuration diagram of an industrial vehicle to which a braking control device for an industrial vehicle according to an embodiment is applied. FIG. 2 is a block diagram showing the functional configuration of the brake control device for the industrial vehicle shown in FIG. 1. FIG. 3 is a timing chart showing an example of the operation of a brake control device for an industrial vehicle. 3 is a flowchart illustrating an example of pre-stop braking processing. It is a flowchart which shows an example of the control process of the control of a brake part, and the power running of a traveling motor.

Embodiments of the present invention will be described in detail below with reference to the drawings. In addition, in the drawings, the same or equivalent elements are given the same reference numerals, and redundant explanations will be omitted.

FIG. 1 is a schematic configuration diagram of an industrial vehicle to which a brake control device for an industrial vehicle according to an embodiment is applied. The industrial vehicle 1 shown in FIG. 1 is, for example, an electric towing tractor, and is used to tow containers loaded with cargo at airports, factories, ports, etc.

The industrial vehicle 1 is configured to be able to execute automatic driving control. Automatic operation is an operating state in which vehicle control is executed to automatically drive the industrial vehicle 1 according to a transport command from, for example, a traffic management system. The operation management system is a so-called control system that performs transportation commands, operation monitoring, vehicle status monitoring, etc. for the industrial vehicle 1. In autonomous driving, the vehicle moves automatically without the need for a worker to perform any driving operations.

The automatic operation here is carried out in a predetermined area including, for example, a runway, takeoff and landing area, taxiway, apron, control tower, hangar, cargo handling area, charging station, etc. at an airport. The industrial vehicle 1 is capable of automatic operation within a predetermined area with a predetermined travel route. In this embodiment, a travel plan is generated that includes stopping the industrial vehicle 1 at a predetermined target stop position on a predetermined travel route. Note that the travel route of the industrial vehicle 1 is not fixed and can be changed from a predetermined route. An unfixed driving route is not a driving route that is difficult to change once set, such as an automated guided vehicle (AGV) that runs along a magnetic tape installed on the road surface, but a map. A travel route that can be changed by changing a travel plan generated based on information, etc.

[Configuration related to running and braking of industrial vehicle 1]
The industrial vehicle 1 includes FL tires 2 and FR tires 3 arranged at the front of the vehicle body, and RL tires 4 and RR tires 5 arranged at the rear of the vehicle body. The industrial vehicle 1 includes a left running motor 6 that drives the RL tires 4 and a right running motor 7 that drives the RR tires 5 as running motors. The travel motor also functions as a braking unit 8 that generates regenerative braking force.

The left travel motor 6 and the right travel motor 7 are AC motors that also function as generators. A left drive unit 6a, which is a reduction gear, is interposed between the left travel motor 6 and the RL tires 4. A right drive unit 7a, which is a reduction gear, is interposed between the right travel motor 7 and the RR tires 5.

The left travel motor 6 is electrically connected to the contactor 9 via a left motor driver 6b. The right travel motor 7 is electrically connected to the contactor 9 via a right motor driver 7b. The left motor driver 6b and the right motor driver 7b have, for example, an inverter, and are electrically connected to the controller 10. In the left motor driver 6b and the right motor driver 7b, the power running and regeneration of the left travel motor 6 and the right travel motor 7 are controlled by the controller 10. The left motor driver 6b and the right motor driver 7b may detect the regenerative current of the left travel motor 6 and the right travel motor 7, respectively.

Contactor 9 is electrically connected to battery B. Further, the contactor 9 is electrically connected to the controller 10. In the contactor 9, power supply from the battery B including emergency stop is controlled by the controller 10.

Battery B is a power supply source for left travel motor 6 and right travel motor 7. The battery B is, for example, a lead-acid battery, and is a storage battery that can store regenerative power generated by regenerative braking of the left travel motor 6 and the right travel motor 7.

When the left travel motor 6 is rotationally driven, the driving force of the left travel motor 6 is transmitted to the RL tire 4 via the left drive unit 6a, and the RL tire 4 rotates. Further, the left travel motor 6 also functions as a generator. Specifically, when the industrial vehicle 1 is braked, the rotation of the RL tires 4 causes the left traveling motor 6 to operate as a generator. That is, regenerative braking of the left traveling motor 6 is performed, regenerative power is generated from the left traveling motor 6, and the RL tires 4 are braked with regenerative braking force.

When the right travel motor 7 is rotationally driven, the driving force of the right travel motor 7 is transmitted to the RR tires 5 via the right drive unit 7a, and the RR tires 5 rotate. Further, the right travel motor 7 also functions as a generator. Specifically, when the industrial vehicle 1 is braked, the rotation of the RR tires 5 causes the right travel motor 7 to operate as a generator. That is, regenerative braking of the right travel motor 7 is performed, regenerative power is generated from the right travel motor 7, and the RR tires 5 are braked with the regenerative braking force.

The industrial vehicle 1 includes an FL disc brake, which is a mechanical brake operated by hydraulic pressure (fluid pressure) in the braking unit 8 and is disposed at the front of the vehicle body and is attached to be able to brake each of the FL tires 2 and the FR tires 3. 8a and an FR disc brake 8b. The industrial vehicle 1 includes an RL drum brake 8c and an RR drum brake 8d, which are disposed at the rear of the vehicle body and are attached to be able to brake the RL tires 4 and the RR tires 5, respectively.

The industrial vehicle 1 includes a master cylinder 31 and an ESC unit 32. The master cylinder 31 has a reservoir tank that stores brake fluid. Although the master cylinder 31 may have a function of generating oil pressure, only the function of a reservoir tank is used here. The reservoir tank is connected to the ESC unit 32 through a hydraulic circuit. Note that in place of the master cylinder 31, a reservoir tank that does not have the function of generating oil pressure may be provided.

The ESC unit 32 is, for example, a hydraulic control unit that integrates a processor, a motor, a pump, and a valve. The processor is, for example, a computing unit such as a CPU (Central Processing Unit). The processor centrally controls, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), and a communication interface.

The ESC unit 32 is electrically connected to the controller 10. The ESC unit 32 has a built-in electric pump, for example, and can increase or decrease the hydraulic pressure in accordance with a hydraulic pressure instruction signal from the controller 10. The ESC unit 32 has a built-in oil pressure sensor, and oil pressure information detected by the oil pressure sensor is transmitted to the controller 10. The ESC unit 32 is controlled by the controller 10 in response to a control signal from the controller 10 based on, for example, oil pressure information.

The ESC unit 32 is connected to the FL disc brake 8a and the FR disc brake 8b through a hydraulic circuit 33 for braking the front wheels. The ESC unit 32 is connected to the RL drum brake 8c and the RR drum brake 8d through a hydraulic circuit 34 for braking the rear wheels.

When the ESC unit 32 increases or decreases the hydraulic pressure in response to a hydraulic pressure instruction signal from the controller 10, hydraulic oil is supplied to each of the hydraulic circuit 33 and the hydraulic circuit 34 independently. As a result, hydraulic oil is supplied to the FL disc brake 8a and the FR disc brake 8b, the FL disc brake 8a and the FR disc brake 8b are operated, and the FL tires 2 and FR tires 3 are braked by mechanical braking force. In addition, independently of the braking of the front wheels, hydraulic oil is supplied to the RL drum brake 8c and the RR drum brake 8d, the RL drum brake 8c and the RR drum brake 8d are operated, and the RL tire 4 and the RR tire 5 are It is braked by braking force.

The industrial vehicle 1 includes a left electromagnetic brake 6c and a right electromagnetic brake 7c, which are attached to be able to brake the left travel motor 6 and the right travel motor 7, respectively. The left electromagnetic brake 6c and the right electromagnetic brake 7c are electrically connected to the controller 10 and are used as parking brakes when the industrial vehicle 1 is parked.

[Configuration related to automatic operation control and braking control of industrial vehicle 1]
FIG. 2 is a block diagram showing the functional configuration of the brake control device for the industrial vehicle shown in FIG. 1. As shown in FIG. The industrial vehicle braking control device 100 includes a controller 10 that controls the braking control and automatic driving control of the industrial vehicle 1. The controller 10 is an electronic control unit including a CPU, ROM, RAM, etc. The controller 10 realizes various functions by, for example, loading a program recorded in a ROM into a RAM, and executing the program loaded into the RAM by a CPU. Note that the controller 10 may be composed of a plurality of electronic units.

The controller 10 is connected to a GNSS receiver 21, a surrounding situation sensor 22, a travel information sensor 23, and a map database 24.

The GNSS receiver 21 measures the position of the industrial vehicle 1 on a map (for example, the latitude and longitude of the industrial vehicle 1) by receiving signals from three or more GNSS satellites. The GNSS receiver 21 transmits the measured position information of the industrial vehicle 1 to the controller 10.

The surrounding situation sensor 22 is an on-vehicle detector that detects the surrounding situation of the vehicle. The surrounding situation sensor 22 includes a camera and a lidar (Light Detection And Ranging). Camera imaging information is used, for example, for road surface pattern recognition and matching. Obstacle information detected by the lidar is used, for example, for the industrial vehicle 1 to avoid danger. The surrounding situation sensor 22 transmits information regarding the surrounding situation of the industrial vehicle 1 to the controller 10.

The traveling information sensor 23 is a detector that detects the traveling state of the industrial vehicle 1. The driving information sensor 23 includes a vehicle speed sensor, an acceleration sensor, and a yaw rate sensor (gyro sensor). The vehicle speed sensor is a detector that detects the speed of the industrial vehicle 1. As the vehicle speed sensor, for example, a speed sensor that is provided in each of the left travel motor 6 and the right travel motor 7 and detects the rotational speed of the left travel motor 6 and the right travel motor 7 is used. The travel information sensor 23 transmits the detected travel information to the controller 10.

The map database 24 is a database that stores map information. The map database 24 is formed, for example, in a storage device (eg, HDD [Hard Disk Drive]) mounted on the industrial vehicle 1. Map information includes road position information, road shape information ( For example, the information includes information on curves, types of straight sections, curvatures of curves, etc.), location information on intersections and branch points, and location information on structures. The map information includes position information of a road surface pattern used to recognize the position of the industrial vehicle 1. Note that the map database 24 may be formed in a server that can communicate with the industrial vehicle 1.

The map information includes information on a predetermined target stopping position. The target stop position is a preset position on a map that is a target for stopping the industrial vehicle 1 during automatic operation. The target stop position may be set, for example, at a hangar, a cargo handling area, a charging station, an entrance to an intersection, a stop line in a traffic zone, or the like. The stop line of the traffic zone means a stop line provided in the middle of the traffic zone (at a position other than an intersection) on the route along which the industrial vehicle 1 travels.

Next, the functional configuration of the controller 10 will be explained. The controller 10 includes a map information acquisition section 11 , a position information acquisition section 12 , a driving information acquisition section (vehicle speed information acquisition section) 13 , and an automatic driving control section 14 . Note that some of the functions of the controller 10 described below may be executed in a server that can communicate with the vehicle.

The map information acquisition unit 11 acquires map information stored in the map database 24. The map information acquisition unit 11 acquires, for example, position information on a road surface pattern used for position recognition of the industrial vehicle 1, information on a target stopping position, and the like.

The position information acquisition unit 12 acquires position information of the industrial vehicle 1 based on the reception result of the GNSS receiver 21. The position information acquisition unit 12 may acquire the position information of the industrial vehicle 1 based on the detection result of the surrounding situation sensor 22 and the map information of the map database 24. The position information acquisition unit 12 acquires the self-position of the industrial vehicle 1 based on the position information of the road surface pattern included in the map information and the relative position information of the road surface pattern with respect to the industrial vehicle 1 detected by the surrounding situation sensor 22. Good too. Note that the position information acquisition unit 12 may estimate the self-position of the industrial vehicle 1 using, for example, a SLAM [Simultaneous Localization And Mapping] method.

The traveling information acquisition unit 13 acquires traveling information of the industrial vehicle 1 based on the detection result of the traveling information sensor 23. The travel information acquisition unit 13 here acquires vehicle speed information of the industrial vehicle 1 based on the detection results of speed sensors provided in each of the left travel motor 6 and the right travel motor 7. The traveling information acquisition unit 13 may acquire the orientation of the industrial vehicle 1 based on the detection result of the gyro sensor.

The automatic driving control unit 14 executes automatic driving control of the industrial vehicle 1 based on the position information, traveling information, and map information. The automatic driving control unit 14 determines the surrounding situation of the industrial vehicle 1 (obstacle position etc.) and the driving conditions (vehicle speed, yaw rate, etc.) recognized from the detection results of the driving information sensor 23, a driving plan along the target route is generated. The target route is set according to the transport command of the traffic management system.

The automatic driving control unit 14 executes automatic driving according to the travel plan. The travel plan includes, for example, a target speed, required acceleration, and required deceleration. The travel plan may include a target steering angle. The automatic driving control unit 14 here transmits control signals to the left drive unit 6a, right drive unit 7a, and ESC unit 32 to perform automatic driving control so that the target speed, required acceleration, and required deceleration are achieved. and performs braking control.

The automatic driving control unit 14 executes pre-stop braking and stop braking based on the vehicle speed information and position information of the industrial vehicle 1. The pre-stop braking refers to a braking process during automatic operation that decelerates the industrial vehicle 1 to such an extent that the industrial vehicle 1 enters a predetermined slow speed state before the target stop position. Pre-stop braking is performed prior to stopping braking.

The pre-stop braking includes braking processing for decelerating the industrial vehicle 1 so that it enters a predetermined slow-moving state. The predetermined slow running state means a running state of the industrial vehicle 1 in which the industrial vehicle 1 can be stopped at the target stop position by increasing the mechanical braking force when the industrial vehicle 1 reaches the target stop position. The slow moving state in this embodiment is, for example, a state where the vehicle speed of the industrial vehicle 1 is the vehicle speed before stopping. The vehicle speed before stopping may be, for example, a predetermined vehicle speed of about 0.3 km/h to 1.5 km/h.

The automatic driving control unit 14 decelerates the industrial vehicle 1 so that the industrial vehicle 1 enters the above-mentioned slow speed state before the target stop position. For example, in pre-stop braking, when the vehicle speed of the industrial vehicle 1 exceeds the pre-stop vehicle speed, the automatic driving control unit 14 performs regenerative priority braking mainly based on the regenerative braking force of the left travel motor 6 and the right travel motor 7. . Regenerative braking is a mode of braking that, in principle, uses regenerative braking force preferentially without operating a mechanical brake. Generally, when applying regenerative braking to the industrial vehicle 1, the mechanical brake is further activated depending on, for example, the amount of cargo on the industrial vehicle 1 and whether the road the industrial vehicle 1 is traveling on is flat or downhill. It depends on whether you can get away with it or not. For example, if the amount of cargo loaded on the industrial vehicle 1 is above a certain level and mechanical braking force is required to decelerate at the required deceleration, or if the road of the industrial vehicle 1 is downhill and the machine is required to decelerate at the required deceleration. Regeneration-prioritizing braking may not always be performed, such as when braking force is required. Except for such cases (when no mechanical braking force is required to decelerate at the requested deceleration), the automatic driving control unit 14 controls the automatic driving control unit 14 to control the vehicle speed of the industrial vehicle 1 in pre-stop braking when the vehicle speed exceeds the pre-stop vehicle speed. In this case, it is possible to brake the industrial vehicle 1 to position P2 using regenerative braking force without operating the mechanical brake.

The pre-stop braking is braking that is performed after the industrial vehicle 1 enters a slow-moving state and before reaching the target stop position, and includes braking processing that involves closing the gap between the sliding members of the mechanical brake. The sliding members of a mechanical brake include, for example, a disc and a brake pad for a disc brake, a drum and a shoe for a drum brake, and the like. In closing the gap between the sliding members of the mechanical brake (hereinafter also simply referred to as "closing the gap"), the mechanical brake is activated in order to increase the responsiveness of the mechanical braking force before the industrial vehicle 1 reaches the target stopping position. be done. In other words, closing the gap refers to reducing the clearance between sliding members so that the sliding members are in contact with each other or can be brought into immediate contact with each other. say. In this embodiment, the gap is closed, and the mechanical brake continues to operate so that the vehicle speed of the industrial vehicle 1 reaches the target vehicle speed, and the left travel motor 6 and the right travel motor 7 are powered to drive the industrial vehicle 1 at a slow speed. . Incidentally, in the case of a non-autonomous vehicle that generates mechanical braking force in response to brake pedal operation and is equipped with an engine equipped with a torque converter, the slow speed state of this embodiment refers to the case where the brake pedal is lightly pressed while creeping. This can be said to be a running state similar to the state in which the sliding members are dragging each other when stepped on.

The automatic operation control unit 14 executes stop braking following the pre-stop braking. Stop braking refers to a braking process in automatic driving that causes the industrial vehicle 1, which has been slowed down by pre-stop braking, to stop at a target stop position. In stop braking, the sliding member of the mechanical brake generates a friction equivalent to the mechanical braking force sufficient to stop the vehicle. By the way, regarding the state of stop braking, if we compare it to the case of a non-autonomous vehicle where mechanical braking force is generated in response to the brake pedal operation, this is the case when the driver depresses the brake pedal to stop a slow-moving vehicle. It can be said that the driving conditions are similar.

For example, the automatic driving control unit 14 may generate a travel plan for executing pre-stop braking and stop braking. FIG. 3 is a timing chart showing an example of the operation of the brake control device for an industrial vehicle. FIG. 3(a) shows the vehicle speed until the industrial vehicle 1 reaches the target stop position P3. As shown in FIG. 3(a), the automatic driving control unit 14 generates a travel plan such that, for example, the industrial vehicle 1 decelerates toward stopping at the target stop position P3. In this travel plan, for example, regenerative braking is performed to decelerate the industrial vehicle 1 to a predetermined deceleration from position P1 to position P2. Further, the industrial vehicle 1 is caused to travel from the position P2 to the target stop position P3 at a predetermined pre-stop vehicle speed.

In the example of FIG. 3, it is assumed that the vehicle speed before stopping is, for example, the target vehicle speed at positions P2 to P3, and is also the vehicle speed threshold. The vehicle speed threshold is a vehicle speed threshold for determining whether or not to close the gap. The vehicle speed threshold value is not particularly limited, but may be set to a vehicle speed of about 0.3 km/h to 1.5 km/h, for example.

As an example of stop braking, the automatic driving control unit 14 calculates a required deceleration and a deceleration start position for decelerating the industrial vehicle 1 or stopping the industrial vehicle 1 at the target stop position P3, according to the generated travel plan, and The braking unit 8 is controlled so that the deceleration becomes the required deceleration. The automatic driving control unit 14 may control the power running of the left travel motor 6 and the right travel motor 7 in conjunction with the braking by the brake unit 8 so that the vehicle speed of the industrial vehicle 1 becomes the target vehicle speed according to the generated travel plan. good.

The automatic driving control unit 14 controls the braking unit 8 using the regenerative braking force and the mechanical braking force instruction value based on the required deceleration calculated according to the travel plan. The regenerative braking force can be, for example, the braking torque generated by the motors when the rotational speed and rotational deceleration of the left traveling motor 6 and the right traveling motor 7 are set as instruction values. The mechanical braking force command value corresponds to a signal of a hydraulic pressure command, and can be, for example, a command value of a hydraulic pressure value given by the ESC unit 32 to the hydraulic circuit 33 and the hydraulic circuit 34.

FIG. 3(b) shows the regenerative braking force until the industrial vehicle 1 reaches the target stop position P3. FIG. 3(c) shows the mechanical braking force instruction value until the industrial vehicle 1 reaches the target stop position P3. As shown in FIGS. 3(b) and 3(c), when the industrial vehicle 1 reaches position P1, regenerative braking is started with a regenerative braking force that provides a predetermined deceleration, and the mechanical brake is activated. deceleration begins without any delay. That is, as an example, when the vehicle speed of the industrial vehicle 1 exceeds the pre-stop vehicle speed during pre-stop braking, the automatic driving control unit 14 prioritizes regeneration mainly based on the regenerative braking force of the left travel motor 6 and the right travel motor 7. Perform braking.

The position P1 is included in the travel plan as a deceleration start position where deceleration by regenerative priority braking is started based on the target stop position P3 and the position where gap closing is started. The target stopping position P3 is acquired based on map information. The position at which gap closing is started is position P2. The position P2 is preset according to how far in front of the target stop position P3 the regeneration priority braking is to be ended in the traveling direction of the industrial vehicle 1. The position at which gap closing is started is, for example, a predetermined distance before the target stop position P3 in the traveling direction of the industrial vehicle 1, or a predetermined speed (for example, vehicle speed before stopping) from the target stop position P3 in the traveling direction of the industrial vehicle 1. ) may be set as a position a predetermined amount of time earlier.

Note that, based on the positions P1 and P2, the automatic driving control unit 14 sets the required deceleration of the industrial vehicle 1 when the vehicle speed of the industrial vehicle 1 exceeds the pre-stop vehicle speed during pre-stop braking as the first deceleration. It may be calculated. The first deceleration is a deceleration in regeneration priority braking. The automatic driving control unit 14 can calculate the first deceleration based on, for example, the target stop position P3, the position where gap closing is started, the position where deceleration is started, the vehicle speed, the vehicle speed before stopping, and the like.

Subsequently, when the industrial vehicle 1 is decelerated by regeneration priority braking, the vehicle speed of the industrial vehicle 1 reaches a predetermined pre-stop vehicle speed at position P2, and enters the above-mentioned slowing state. That is, the vehicle speed of the industrial vehicle 1 becomes equal to or lower than the predetermined pre-stop vehicle speed.

The automatic driving control unit 14 operates a mechanical brake to close the gap when the vehicle speed of the industrial vehicle 1 becomes equal to or less than a predetermined pre-stop vehicle speed during pre-stop braking. In this embodiment, as an example of gap filling, as shown in FIGS. 3(b) and 3(c), the regenerative braking force is set to 0 at position P2, and the mechanical braking force instruction value is set to the first pressure. It is said that The first pressure is a value of fluid pressure (hydraulic pressure in this case) that activates the mechanical brake to close the gap. The first pressure is smaller than the second pressure that activates the mechanical brake to stop the industrial vehicle 1 that has reached the target stop position P3.

Further, as shown in the slope (acceleration) of the vehicle speed of the industrial vehicle 1 in FIG. 3(a), the deceleration due to gap closing is smaller than the deceleration due to regeneration priority braking. That is, the deceleration of the industrial vehicle 1 when the vehicle speed of the industrial vehicle 1 becomes equal to or lower than the pre-stop vehicle speed during pre-stop braking is the deceleration when the vehicle speed of the industrial vehicle 1 is greater than the pre-stop vehicle speed during the pre-stop braking. smaller than The automatic driving control unit 14 may calculate, as the second deceleration, the required deceleration of the industrial vehicle 1 when the vehicle speed of the industrial vehicle 1 becomes equal to or lower than the pre-stop vehicle speed during pre-stop braking. The second deceleration is the required deceleration during gap closing. The second deceleration may be set in advance, for example, and stored in the controller 10. The automatic operation control unit 14 operates at least the mechanical brake so that the deceleration of the industrial vehicle 1 becomes the second deceleration, for example, to close the gap.

Note that here, the second deceleration is 0 because the vehicle speed of the industrial vehicle 1 is feedback-controlled using the pre-stop vehicle speed (constant value) as the target value until the position of the industrial vehicle 1 reaches the target stop position P3. be. The vehicle speed of the industrial vehicle 1 is set to a target value by canceling out both the mechanical braking force for closing the gap or the mechanical braking force for closing the gap and the power running of the left traveling motor 6 and the right traveling motor 7. The vehicle speed is controlled to approach the vehicle speed before stopping. That is, when the vehicle speed of the industrial vehicle 1 becomes equal to or lower than the pre-stop vehicle speed during pre-stop braking, the automatic driving control unit 14 maintains the vehicle speed of the industrial vehicle 1 at the target vehicle speed until the position of the industrial vehicle 1 reaches the target stop position P3. The mechanical brake is operated so that the left traveling motor 6 and the right traveling motor 7 are powered.

After that, when the industrial vehicle 1 reaches the target stop position P3, the pre-stop braking shifts to the stop braking, the power running of the left travel motor 6 and the right travel motor 7 is terminated, and the mechanical braking force instruction value is changed to the second pressure. It is said that That is, in this embodiment, as an example of stop braking, the mechanical braking force instruction value is the second pressure. As a result, the industrial vehicle 1 is stopped at the target stop position P3 with the mechanical braking force with reduced response delay. The automatic driving control unit 14 may calculate the required deceleration of the industrial vehicle 1 when the industrial vehicle 1 reaches the target stop position P3 as the third deceleration. The third deceleration is a required deceleration for stop braking to stop the industrial vehicle 1 that has reached the target stop position P3 at the target stop position P3. The third deceleration may be set in advance, for example, and stored in the controller 10.

[An example of calculation processing by the controller 10]
Next, an example of arithmetic processing by the controller 10 will be described. FIG. 4 is a flowchart illustrating an example of pre-stop braking processing. The process shown in FIG. 4 is executed, for example, when the industrial vehicle 1 during automatic operation travels toward a target stop position.

As shown in FIG. 4, the controller 10 acquires vehicle speed information of the industrial vehicle 1 using the travel information acquisition unit 13 in S01. The traveling information acquisition unit 13 acquires vehicle speed information of the industrial vehicle 1 based on the detection result of the traveling information sensor 23, for example.

In S02, the controller 10 uses the position information acquisition unit 12 to acquire the vehicle position. The position information acquisition unit 12 acquires the position information of the industrial vehicle 1 based on the reception result of the GNSS receiver 21, for example.

In S03, the controller 10 controls the braking unit 8 and the power running of the travel motor using the automatic operation control unit 14. The automatic operation control unit 14 controls the braking unit 8 and the power running of the travel motor, for example, based on the travel plan generated by the automatic operation control unit 14. Specifically, the controller 10 performs the process illustrated in FIG. 5 as the process of S03.

FIG. 5 is a flowchart illustrating an example of a process for controlling the braking unit and controlling the power running of the travel motor. As shown in FIG. 5, in S11, the controller 10 uses the automatic driving control unit 14 to determine whether the vehicle speed of the industrial vehicle 1 exceeds a vehicle speed threshold. The automatic driving control unit 14 determines whether the vehicle speed of the industrial vehicle 1 exceeds the vehicle speed threshold, for example, based on the acquisition result of the driving information acquisition unit 13 and the vehicle speed threshold stored in advance.

When the automatic driving control unit 14 determines that the vehicle speed of the industrial vehicle 1 exceeds the vehicle speed threshold (S11: YES), the controller 10 causes the automatic driving control unit 14 to first reduce the required deceleration in S12. Calculate as speed. The controller 10 may calculate the deceleration start position in S12. In S13, the controller 10 uses the automatic operation control unit 14 to perform regeneration-priority braking. For example, the automatic driving control unit 14 performs regenerative braking mainly based on the regenerative braking forces of the left travel motor 6 and the right travel motor 7 so that the deceleration of the industrial vehicle 1 becomes the first deceleration. Thereafter, the controller 10 ends the process of FIG. 5 and the process of FIG. 4, and repeats the process of FIG. 4 after a predetermined calculation cycle.

On the other hand, if the automatic driving control unit 14 determines that the vehicle speed of the industrial vehicle 1 does not exceed the vehicle speed threshold (the vehicle speed is below the vehicle speed threshold) (S11: NO), the controller 10 performs automatic driving control in S14. The unit 14 determines whether the industrial vehicle 1 has not yet reached the target stop position. The automatic driving control unit 14 determines whether the industrial vehicle 1 has not reached the target stop position, for example, based on the acquisition result of the position information acquisition unit 12 and the target stop position.

When the automatic operation control unit 14 determines that the industrial vehicle 1 has not reached the target stop position (S14: YES), the controller 10 causes the automatic operation control unit 14 to reduce the required deceleration to a second value in S15. Calculate as speed. In S16, the controller 10 uses the automatic operation control unit 14 to close the gap. To close the gap, the automatic driving control unit 14 operates the mechanical brake at the first pressure and powers the left traveling motor 6 and the right traveling motor 7 so that the vehicle speed of the industrial vehicle 1 becomes the target vehicle speed. Alternatively, the automatic operation control unit 14 may operate the mechanical brake at the first pressure so that the deceleration of the industrial vehicle 1 becomes the second deceleration to close the gap. As a result, the industrial vehicle 1 travels in a predetermined slow speed. Thereafter, the controller 10 ends the process of FIG. 5 and the process of FIG. 4, and repeats the process of FIG. 4 after a predetermined calculation cycle.

On the other hand, if the automatic operation control unit 14 determines that the industrial vehicle 1 has not reached the target stop position (the industrial vehicle 1 has reached the target stop position) (S14: NO), the controller 10 performs pre-stop braking. As a transition from to stop braking, in S17, the automatic operation control unit 14 calculates the required deceleration as a third deceleration. In S18, the controller 10 uses the automatic driving control unit 14 to perform stop braking to stop the industrial vehicle 1. The automatic operation control unit 14 operates the mechanical brake at the second pressure, for example, as stop braking so that the deceleration of the industrial vehicle 1 becomes the third deceleration. Note that the industrial vehicle 1 continues to stop at the position P3 due to the mechanical braking force caused by maintaining the second pressure. Thereafter, the controller 10 ends the process of FIG. 5 and the process of FIG. 4, and repeats the process of FIG. 4 after a predetermined calculation cycle.

[Action and effect]
As described above, in the industrial vehicle braking control device 100 according to the present embodiment, the mechanical brake is activated when the vehicle speed of the industrial vehicle 1 becomes equal to or less than a predetermined vehicle speed threshold during pre-stop braking. This reduces the physical gap that causes a delay in the response of the mechanical braking force in the mechanical brake. As a result, the mechanical brake is in a state where the response delay of the mechanical braking force is reduced compared to the case where the mechanical brake is not activated. Therefore, according to the braking control device 100 for an industrial vehicle, it is possible to reduce the response delay of the mechanical braking force when the industrial vehicle 1 is stopped at the target stop position using the hydraulically operated mechanical brake.

In the industrial vehicle braking control device 100, the deceleration of the industrial vehicle 1 when the vehicle speed of the industrial vehicle 1 becomes less than or equal to the vehicle speed threshold during pre-stop braking is determined as follows: It is smaller than the deceleration when it is larger. As a result, compared to the case where the vehicle speed exceeds the vehicle speed threshold, the speed change when the industrial vehicle 1 approaches the target stopping position at a vehicle speed below the vehicle speed threshold becomes gentler, so the industrial vehicle 1 is more appropriately positioned at the target stopping position. This makes it easier to stop the vehicle.

In the industrial vehicle braking control device 100, when the vehicle speed of the industrial vehicle 1 becomes equal to or less than the vehicle speed threshold during pre-stop braking, the automatic driving control unit 14 controls the industrial vehicle 1 until the position of the industrial vehicle 1 reaches the target stop position. The mechanical brake is operated so that the vehicle speed becomes the target vehicle speed, and the left travel motor 6 and right travel motor 7 are powered. Thereby, the accuracy of the stop position of the industrial vehicle 1 with respect to the target stop position can be stabilized by causing the industrial vehicle 1 to travel at the target vehicle speed and approach the target stop position. Note that the stop position accuracy is an index that indicates how much error the stop position of the industrial vehicle 1 has with respect to the target stop position.

In the braking control device 100 for an industrial vehicle, the automatic driving control unit 14 mainly uses the regenerative braking force of the left travel motor 6 and the right travel motor 7 when the vehicle speed of the industrial vehicle 1 exceeds the vehicle speed threshold during pre-stop braking. Performs regeneration-priority braking. In this case, during regeneration-priority braking, the mechanical brake is likely to be in a state where there is a delay in the response of the mechanical braking force due to the above-mentioned physical gap. Therefore, the effect of reducing the response delay of the mechanical braking force due to the above-mentioned gap reduction becomes remarkable.

In the industrial vehicle braking control device 100, the automatic driving control unit 14 controls the mechanical brake by setting the hydraulic pressure of the mechanical brake to the first pressure when the vehicle speed of the industrial vehicle 1 becomes equal to or lower than the vehicle speed threshold during pre-stop braking. When the industrial vehicle 1 is activated and the position of the industrial vehicle 1 reaches the target stop position, stop braking is performed by setting the hydraulic pressure of the mechanical brake to a second pressure that is higher than the first pressure. Thereby, stop braking and pre-stop braking can be performed with a simple configuration in which the hydraulic pressure of the mechanical brake is set to the first pressure or the second pressure.

Note that when the industrial vehicle 1 employs a drum brake as a mechanical brake, for example, the shoe clearance is reduced in advance by closing the gap by the braking control device 100 of the industrial vehicle before the industrial vehicle 1 reaches the target stop position. You can keep it. As a result, compared to the conventional technique described in Patent Document 1, which operates the mechanical brake after the industrial vehicle 1 reaches the target stop position to increase the shoe clearance reduction speed, the speed of shoe clearance reduction is much higher. The industrial vehicle 1 that has reached the target stop position can be stopped with a responsive mechanical braking force. Since the shoe clearance can be reduced in advance, it is not necessary to increase the performance of the motor, pump, etc. of the ESC unit 32 to increase the oil pressure in order to increase the speed at which the shoe clearance is reduced, and the responsiveness of the mechanical braking force is improved. be able to. Furthermore, since the shoe clearance can be reduced in advance, even if the shoe clearance changes, for example after replacing the brake shoes, there is no need to adjust the control parameters for closing the gap, such as the oil pressure rise amount in the prior art.

[Modified example]
Although the embodiments according to the present invention have been described above, the present invention is not limited to the embodiments described above.

In the embodiment described above, when the vehicle speed of the industrial vehicle 1 exceeds the vehicle speed threshold in pre-stop braking, the automatic driving control unit 14 performs regenerative braking that mainly uses the regenerative braking force of the left traveling motor 6 and the right traveling motor 7. conducted, but is not limited to this. For example, even if the vehicle speed of the industrial vehicle 1 exceeds the vehicle speed threshold during pre-stop braking, the mechanical brake may be temporarily activated. Even in this case, for example, if the mechanical brake is not activated when the vehicle speed of the industrial vehicle 1 approaches the vehicle speed threshold, the clearance between the sliding members of the mechanical brake may increase again, as described above. The effect of reducing the response delay of mechanical braking force is effectively achieved by closing the gap.

In the embodiment described above, when the vehicle speed of the industrial vehicle 1 becomes equal to or less than the vehicle speed threshold during pre-stop braking, the automatic driving control unit 14 controls the vehicle speed of the industrial vehicle 1 to reach the target stop position until the position of the industrial vehicle 1 reaches the target stop position. Although the mechanical brake was operated and the left travel motor 6 and right travel motor 7 were powered to maintain the vehicle speed, it is sufficient to operate at least the mechanical brake. For example, when the vehicle speed of the industrial vehicle 1 becomes equal to or lower than the vehicle speed threshold during pre-stop braking, the automatic driving control unit 14 controls the left travel motor 6 and the right travel motor 7 until the position of the industrial vehicle 1 reaches the target stop position. For example, the mechanical brake may continue to operate at a constant first pressure without power running. Note that the oil pressure for operating the mechanical brake may be changed.

In the above embodiment, the deceleration of the industrial vehicle 1 when the vehicle speed of the industrial vehicle 1 becomes equal to or lower than the vehicle speed threshold during pre-stop braking is the same as the deceleration of the industrial vehicle 1 when the vehicle speed of the industrial vehicle 1 is greater than the vehicle speed threshold during the pre-stop braking. Although it is made smaller than the speed, it is not limited to this. For example, both decelerations may be equal to each other. Alternatively, the deceleration of the industrial vehicle 1 when the vehicle speed of the industrial vehicle 1 becomes less than or equal to the vehicle speed threshold during pre-stop braking is less than the deceleration when the vehicle speed of the industrial vehicle 1 is greater than the vehicle speed threshold during the pre-stop braking. May be made larger.

In the above embodiment, the industrial vehicle 1 is not provided with a brake pedal and a master cylinder, but may be provided with a brake pedal and a master cylinder for maintenance purposes, which are not used in automatic driving, for example.

In the above embodiment, an electric towing tractor as shown in FIG. 1 is illustrated as the industrial vehicle 1, but the industrial vehicle 1 is not limited to this, and may be, for example, an electric forklift or a hybrid industrial vehicle. It's okay. In short, the braking unit is equipped with a travel motor that generates regenerative braking force and a mechanical brake that is activated by fluid pressure to generate mechanical braking force, and is used to automatically stop an industrial vehicle at a predetermined target stop position. Any industrial vehicle that can perform front braking may be used.

The configuration for automatic operation of the industrial vehicle 1 is not limited to the example of the embodiment described above. For example, although a lidar is used as the surrounding situation sensor 22, another sensor may be used instead.

In the above embodiment, a mechanical brake operated by hydraulic pressure as the fluid pressure was exemplified, but a mechanical brake operated by pneumatic pressure as the fluid pressure may also be used.

In the above embodiment, the gap is closed when the vehicle speed of the industrial vehicle 1 becomes equal to or lower than the vehicle speed threshold before the target stopping position. Based on the detection result of the situation sensor 22 and the map information of the map database 24, the gap closing may be performed when the industrial vehicle 1 reaches a position within a predetermined range (for example, a predetermined distance) from the target stopping position. .

At least some of the embodiments and various modifications described above may be combined arbitrarily.

DESCRIPTION OF SYMBOLS 1... Industrial vehicle, 6... Left travel motor (traveling motor), 7... Right travel motor (traveling motor), 8... Braking part, 8a... FL disc brake (mechanical brake), 8b... FR disc brake (mechanical brake), 8c...RL drum brake (mechanical brake), 8d...RR drum brake (mechanical brake), 10...controller, 11...map information acquisition section, 12...location information acquisition section, 13...driving information acquisition section, 14...automatic driving control Section 100...braking control device for industrial vehicles.

Claims (5)

A braking control device for an industrial vehicle comprising, as a braking unit, a travel motor that generates a regenerative braking force and a mechanical brake that is operated by fluid pressure and generates a mechanical braking force,
a vehicle speed information acquisition unit that acquires vehicle speed information of the industrial vehicle;
a position information acquisition unit that acquires position information of the industrial vehicle;
automatic stop braking that automatically stops the industrial vehicle at a predetermined target stop position based on the vehicle speed information and the position information; and automatic pre-stop braking that decelerates the industrial vehicle before the stop braking. An operation control unit;
The automatic driving control unit is a braking control device for an industrial vehicle that operates the mechanical brake when the vehicle speed of the industrial vehicle becomes equal to or less than a predetermined vehicle speed threshold during the pre-stop braking. The deceleration of the industrial vehicle when the vehicle speed of the industrial vehicle becomes equal to or less than the vehicle speed threshold during the pre-stop braking is the deceleration when the vehicle speed of the industrial vehicle is greater than the vehicle speed threshold during the pre-stop braking. The braking control device for an industrial vehicle according to claim 1, which is smaller than the above. When the vehicle speed of the industrial vehicle becomes equal to or less than the vehicle speed threshold during the pre-stop braking, the automatic driving control unit controls the vehicle speed of the industrial vehicle to be the target vehicle speed until the position of the industrial vehicle reaches the target stop position. The braking control device for an industrial vehicle according to claim 1 or 2, wherein the mechanical brake is operated and the travel motor is powered so that the mechanical brake is operated. The automatic driving control unit performs regenerative braking based on the regenerative braking force of the travel motor when the vehicle speed of the industrial vehicle exceeds the vehicle speed threshold in the pre-stop braking. A braking control device for an industrial vehicle according to any one of the items. The automatic operation control unit includes:
When the vehicle speed of the industrial vehicle becomes equal to or lower than the vehicle speed threshold during the pre-stop braking, the mechanical brake is activated by setting the fluid pressure to a first pressure;
According to any one of claims 1 to 4, the stop braking is performed by setting the fluid pressure to a second pressure greater than the first pressure when the position of the industrial vehicle reaches the target stop position. A braking control device for the industrial vehicle described above.

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