JP7374021B2 - work vehicle - Google Patents

Description

The present invention relates to a work vehicle that performs various tasks while moving forward or backward.

Work vehicles such as wheel loaders perform multiple types of work such as excavation work, loading work, and transport work while moving forward or backward. At this time, the operator in the driver's cab points out that when moving forward, it may be difficult to see what's ahead due to the work equipment installed at the front of the vehicle, and when moving backwards, the engine installed at the rear of the vehicle may be difficult to see. Rear visibility is not good due to covers etc. Therefore, some work vehicles are equipped with a system for detecting obstacles and avoiding collisions with the obstacles.

For example, Patent Document 1 discloses a side sensor that detects the presence of an object in a predetermined range behind the vehicle body, and a stop control means that stops and controls the running of the vehicle body. A collision prevention device for a construction machine when reversing is disclosed, in which when the presence of an object is detected, a parking brake valve is de-energized by a stop control means, a braking force is applied to the wheels, and the vehicle body is stopped.

JP 2019-31823 Publication

However, the collision prevention device for construction machinery when reversing as described in Patent Document 1 stops the vehicle body by turning off the power to the parking brake valve, that is, by operating the parking brake. If the transmission speed is set to a high speed, the vehicle will continue to move backward due to inertia, and it will take time to come to a complete stop, which may cause the vehicle to collide with an obstacle.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a work vehicle that is capable of avoiding a collision with an obstacle without relying on the braking force of an existing brake device when an obstacle is detected in the direction of movement of the vehicle body. There is a particular thing.

In order to achieve the above object, the present invention provides a vehicle body provided with a plurality of wheels, an engine mounted on the vehicle body, a torque converter that amplifies the torque transmitted from the engine, a forward clutch, and a vehicle body equipped with a plurality of wheels. A transmission that controls the reverse clutch with an electromagnetic control valve to transmit the torque output from the torque converter to the plurality of wheels after cutting off or shifting the gear; and the forward clutch and the reverse clutch. A work vehicle comprising: a controller that controls engagement and disengagement; an obstacle detection device that detects an obstacle and measures a distance between the vehicle body and the obstacle; and a vehicle speed sensor that detects vehicle speed. and the controller stores a stopping distance of the vehicle body during full braking according to the vehicle speed as a threshold distance, and the obstacle detection device detects the obstacle in the direction in which the vehicle body is traveling. is detected, and the vehicle body is traveling only when it is determined that the measured distance measured by the obstacle detection device is shorter than the threshold distance according to the vehicle speed detected by the vehicle speed sensor. A switching control signal for switching the traveling direction of the vehicle body to a direction opposite to the direction is output to the electromagnetic control valve, and the obstacle detection device detects the obstacle in the direction in which the vehicle body is traveling. However, if it is determined that the measured distance is equal to or greater than the threshold distance corresponding to the vehicle speed detected by the vehicle speed sensor, the switching control signal is not output to the electromagnetic control valve.

According to the present invention, when an obstacle is detected in the traveling direction of the vehicle body, a collision with the obstacle can be avoided without relying on the braking force of an existing brake device. Problems, configurations, and effects other than those described above will be made clear by the following description of the embodiments.

1 is an external side view showing an example of the configuration of a wheel loader according to an embodiment of the present invention. It is an explanatory view explaining a rear millimeter wave radar. FIG. 2 is a diagram showing the configuration of a travel drive system of a wheel loader. FIG. 2 is a functional block diagram showing functions of a controller. It is a graph showing the relationship between vehicle speed and stopping distance of the vehicle body during full braking. 3 is a flowchart showing the flow of processing executed by the controller.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, as one aspect of a work vehicle according to an embodiment of the present invention, a wheel loader that performs a cargo handling operation of excavating work objects such as earth and sand and minerals and loading them onto a dump truck or the like will be described.

<Configuration of wheel loader 1>
First, the configuration of the wheel loader 1 will be explained with reference to FIGS. 1 and 2.

FIG. 1 is an external side view showing a configuration example of a wheel loader 1 according to an embodiment of the present invention. FIG. 2 is an explanatory diagram illustrating the rear millimeter wave radar 61R.

The wheel loader 1 is an articulated work vehicle that is steered by bending the vehicle body around the center. Specifically, a front frame 1A, which is the front part of the vehicle body, and a rear frame 1B, which is the rear part of the vehicle body, are connected by a center joint 10 so as to be rotatable in the left-right direction, and the front frame 1A is connected to the rear frame 1B. In contrast, it bends in the left and right direction.

The vehicle body is provided with four wheels 11, two wheels 11 are provided as front wheels 11A on both left and right sides of the front frame 1A, and the remaining two wheels 11 are provided as rear wheels 11B on both left and right sides of the rear frame 1B. ing. In addition, in FIG. 1, only the left front wheel 11A and the rear wheel 11B are shown among the left and right pair of front wheels 11A and rear wheels 11B. Further, there is no particular restriction on the specific number of wheels 11 provided on the vehicle body.

A hydraulically driven cargo handling device 2 used for cargo handling work is attached to the front part of the front frame 1A. The cargo handling device 2 includes a lift arm 21 whose base end is attached to the front frame 1A, two lift arm cylinders 22 that drive the lift arm 21, and a bucket 23 attached to the tip of the lift arm 21. It has a bucket cylinder 24 that drives the bucket 23, and a bell crank 25 that is rotatably connected to the lift arm 21 and forms a link mechanism between the bucket 23 and the bucket cylinder 24. Note that the two lift arm cylinders 22 are arranged side by side in the left-right direction of the vehicle body, but in FIG. 1, only the lift arm cylinder 22 arranged on the left side is shown by a broken line.

The two lift arm cylinders 22 are each supplied with hydraulic oil discharged from a hydraulic pump, and the rods 220 extend and contract, thereby driving the lift arms 21. Similarly, the bucket cylinder 24 is supplied with hydraulic oil discharged from the hydraulic pump, and the rod 240 expands and contracts, thereby driving the bucket 23 .

The lift arm 21 rotates upward relative to the front frame 1A when the rods 220 of the two lift arm cylinders 22 extend, and rotates downward relative to the front frame 1A when the rods 220 contract. .

The bucket 23 is a work tool for scooping and discharging earth and sand, and leveling the ground.The bucket 23 rotates (tilts) upward relative to the lift arm 21 by extending the rod 240 of the bucket cylinder 24. ), and as the rod 240 contracts, it rotates (dumps) downward with respect to the lift arm 21.

Note that the bucket 23 can be replaced with various attachments, such as a blade, and the wheel loader 1 can also perform snow removal work in addition to excavation work and dozing work using the bucket 23. can.

The rear frame 1B includes a driver's cab 12 in which an operator rides, a machine room 13 that houses various devices necessary for driving the wheel loader 1, and a balance with the cargo handling device 2 to prevent the vehicle body from tilting. A counterweight 14 is provided for this purpose. In the rear frame 1B, the driver's cab 12 is located at the front, the counterweight 14 is located at the rear, and the machine room 13 is located between the driver's cab 12 and the counterweight 14.

Due to the characteristics of cargo handling operations, the wheel loader 1 is often operated while moving the vehicle body forward or backward, and the operator in the driver's cab 12 needs to operate the wheel loader 1 while checking the front or rear. However, for the operator in the cab 12, it may be difficult to see the front due to the cargo handling equipment 2 installed at the front of the vehicle, and it may be difficult to see the rear due to the engine cover installed at the rear of the vehicle. There are cases.

Therefore, in the wheel loader 1, the front millimeter wave radar 61F, which detects obstacles in front of the vehicle body, is located in the upper front side of the driver's cab 12, and the rear millimeter wave radar 61R, which detects obstacles in the rear of the vehicle body, is located at the counter. They are each attached to the upper part of the weight 14 (at the rear of the vehicle body). Here, "obstacles" are things that can obstruct the movement of the wheel loader 1, and include, for example, other work vehicles, installed equipment, workers, etc. that exist around the wheel loader 1. . Note that there is no particular restriction on the mounting location as long as the front millimeter wave radar 61F can detect an obstacle in front, and the rear millimeter wave radar 61R can detect an obstacle in the rear.

For example, as shown in FIG. 2, the rear millimeter wave radar 61R detects an obstacle to measure). The forward millimeter wave radar 61F also has the same configuration as the rear millimeter wave radar 61R, and these millimeter wave radars 61F and 61R each detect an obstacle and measure the distance between the vehicle body and the obstacle. This is one aspect of an obstacle detection device. Note that the obstacle detection device is not limited to a millimeter wave radar, and for example, a stereo camera or the like may be used. Obstacle detection signals and data regarding the measured distance L output from each of the forward millimeter wave radar 61F and the rear millimeter wave radar 61R are input to the controller 5, which will be described later.

<Traveling drive system of wheel loader 1>
Next, the traveling drive system of the wheel loader 1 will be explained with reference to FIG. 3.

FIG. 3 is a diagram showing the configuration of the traveling drive system of the wheel loader 1. As shown in FIG.

The running of the wheel loader 1 is controlled by a torque converter type running drive system, and includes an engine 30, a torque converter 31 (hereinafter referred to as "torque converter 31") connected to the output shaft of the engine 30, A transmission 32 connected to the output shaft of the torque converter 31 is provided. The driving force of the engine 30 is transmitted to the four wheels 11 via the torque converter 31 and the transmission 32, thereby driving the four wheels 11 and causing the vehicle to travel. These engine 30, torque converter 31, and transmission 32 are each controlled based on a command signal (command current) output from controller 5.

The torque converter 31 is a fluid clutch composed of an impeller, a turbine, and a stator. ) is 1 or more. This torque ratio becomes smaller as the torque converter speed ratio e (=rotational speed N2 of the output shaft/rotational speed N1 of the input shaft), which is the ratio between the rotational speed of the input shaft and the rotational speed of the output shaft of the torque converter 31, increases. . In this way, the torque converter 31 changes the rotational speed of the engine 30 and transmits it to the transmission 32.

The transmission 32 includes a forward clutch 32F, a reverse clutch 32R, a clutch mechanism including a plurality of speed clutches (not shown), and a gear mechanism including a plurality of speed gears (not shown). , switches the traveling direction of the vehicle body, that is, forward and reverse, and also switches to one of the speed stages selected from a plurality of speed stages. That is, the transmission 32 changes the torque, rotational speed, and rotational direction of the output shaft of the torque converter 31 and then transmits the torque to the four wheels 11 .

The forward clutch 32F is controlled by a forward electromagnetic control valve 321, and the reverse clutch 32R is controlled by a reverse electromagnetic control valve 322. The forward electromagnetic control valve 321 and the reverse electromagnetic control valve 322 are each driven according to a control signal output from the controller 5.

The wheel loader 1 moves forward when the forward clutch 32F is engaged and the reverse clutch 32R is released, and moves backward when the forward clutch 32F is released and the reverse clutch 32R is engaged. Switching between forward and backward movement of the wheel loader 1 is performed by a forward/reverse movement switching lever 41 provided in the driver's cab 12 (see FIG. 1). When the forward/reverse switching lever 41 is switched to the forward position, it outputs a traveling direction switching signal related to forward movement to the controller 5, and when switched to the reverse position, it outputs a traveling direction switching signal related to reverse movement to the controller 5.

Further, when the brake pedal 44 is depressed while the forward/reverse switching lever 41 is operated to the forward or reverse position, the engaged forward clutch 32F or reverse clutch 32R is released, and the four wheels Braking force is applied to 11, and the vehicle body stops. Note that when the forward/reverse switching lever 41 is operated to the neutral position, both the forward clutch 32F and the reverse clutch 32R are released, and the vehicle comes to a stopped state.

Similarly, the plurality of speed stage clutches are each controlled by an electromagnetic control valve (not shown) that is driven in accordance with a command signal output from the controller 5. By respectively engaging or disengaging the plurality of speed gear clutches, the combination of the plurality of speed change gears is controlled so that the gear ratio corresponds to the speed gear selected by the operator. In the wheel loader 1, the speed stage of the transmission 32 can be selected from four speed stages by operating a shift switch 42 provided in the driver's cab 12.

Specifically, the first speed stage is the lowest speed stage of the transmission 32, and is selected during work that requires traction, such as excavation work or hill climbing work. The second speed stage is a speed stage set one step larger than the first speed stage, which is the lowest speed stage of the transmission 32, and is selected, for example, during a dump approach operation. The 3rd speed stage is a speed stage set one stage larger than the 2nd speed stage, and the 4th speed stage is a speed stage set further one stage larger than the 3rd speed stage, and is the highest speed stage of the transmission 32. It is. These three speed stages and four speed stages are high speed stages selected, for example, when transporting a load.

In a torque converter-type travel drive system, first, when an operator depresses an accelerator pedal 43 provided in the driver's cab 12, the engine 30 rotates according to the amount of pedal depression, and as the engine 30 rotates, the input shaft of the torque converter 31 rotates. rotates. Then, the output shaft of the torque converter 31 rotates according to the set torque converter speed ratio e, and the output torque from the torque converter 31 is shifted by the transmission 32 and then sent to the four wheels 11 via the propeller shaft 15 and the axle 16. The wheel loader 1 travels by each transmission.

The vehicle speed of the wheel loader 1 is detected by a vehicle speed sensor 62 attached to the propeller shaft 15. Specifically, the vehicle speed sensor 62 detects the vehicle speed based on the rotation speed of the propeller shaft 15. When the vehicle speed sensor 62 detects the vehicle speed V, it outputs the data to the controller 5.

When the operator wants to stop the wheel loader 1 while it is running, the operator depresses the brake pedal 44. The greater the amount of depression of the brake pedal 44, the greater the braking force applied to the four wheels 11, resulting in sudden braking. For example, when an obstacle is detected by the front millimeter wave radar 61F or the rear millimeter wave radar 61R, the operator depresses the brake pedal 44 to avoid collision of the vehicle body with the obstacle. However, since the braking force varies depending on the operator's operation, it may not be possible to stop the vehicle in time. In addition, when the speed stage of the transmission 32 is a high speed stage, that is, when the wheel loader 1 is moving at high speed, the vehicle body continues to move backward due to inertia, and it takes time to completely stop, causing an obstacle. Sometimes they collide with things.

Since the wheel loader 1 performs a series of operations by switching between forward and reverse movement, this characteristic can be used to detect an obstacle behind the vehicle while it is moving backward (as shown in Fig. 2). The system generates braking force by switching the vehicle's direction of travel forward, and by switching the vehicle's direction of travel to reverse if an obstacle is detected in front of it while the vehicle is moving forward. .

That is, the wheel loader 1 controls the engagement and disengagement of the forward clutch 32F and the reverse clutch 32R of the transmission 32 by the controller 5, so that the wheel loader 1 moves in the direction opposite to the direction in which the vehicle body is traveling (forward direction or reverse direction). The direction of movement of the vehicle body is switched to the direction (reverse direction or forward direction) to generate a braking force on the vehicle body that is greater than the braking force generated by the existing brake device mounted on the vehicle body.

Note that unlike general passenger cars, work vehicles such as the wheel loader 1 have the capacity of the forward clutch 32F and the capacity of the reverse clutch 32R set to be the same, so that the capacity of the forward clutch 32F and the reverse clutch 32R are set to be the same. It is possible to switch between forward and backward movement.

<Control by controller 5>
Next, control by the controller 5 will be explained with reference to FIGS. 4 to 6. In the following, the control of the controller 5 in the case where the rear millimeter wave radar 61R detects an obstacle while the vehicle is moving backwards and switches the traveling direction of the vehicle from the reverse direction to the forward direction will be described as an example. A description of the control of the controller 5 when the forward millimeter wave radar 61F detects an obstacle while the vehicle is moving forward and switches the traveling direction of the vehicle body from the forward direction to the reverse direction will be omitted.

(Configuration of controller 5)
First, the configuration of the controller 5 will be explained with reference to FIGS. 4 and 5.

FIG. 4 is a functional block diagram showing the functions that the controller 5 has. FIG. 5 is a graph showing the relationship between the vehicle speed and the stopping distance of the vehicle during full braking.

The controller 5 includes a CPU, RAM, ROM, input I/F, and output I/F connected to each other via a bus. Various operating devices such as the forward/reverse switching lever 41 and the switching control selection switch 45, as well as various sensors such as the rear millimeter wave radar 61R and the vehicle speed sensor 62, are connected to the input I/F, and the forward electromagnetic control valve 321, A reverse electromagnetic control valve 322 and the like are connected to the output I/F.

The switching control selection switch 45 determines whether to enable switching control that causes the controller 5 to switch the traveling direction of the vehicle body to the forward direction when the rear millimeter wave radar 61R detects an obstacle while the vehicle body is moving backward. This is one aspect of a selection device that selects a selection device, and in this embodiment, it is provided in the driver's cab 12 (see FIG. 1). The switching control selection switch 45 outputs a selection signal to the controller 5 when the switching control by the controller 5 is selected to be valid, that is, when it is in the ON state.

In such a hardware configuration, the CPU reads a control program (software) stored in a recording medium such as a ROM or an optical disk, expands it onto the RAM, and executes the expanded control program. The functions of the controller 5 are realized in cooperation with the hardware.

In this embodiment, the controller 5 is described as a computer configured by a combination of software and hardware; however, the controller 5 is not limited to this, and for example, as an example of the configuration of another computer, the controller 5 may be configured on the side of the wheel loader 1. An integrated circuit may be used to implement the functions of the control program to be executed.

As shown in FIG. 4, the controller 5 includes a data acquisition section 51, an obstacle determination section 52, a distance determination section 53, a storage section 54, a signal output section 55, and a stop determination section 56.

The data acquisition unit 51 receives a selection signal output from the switching control selection switch 45, a traveling direction switching signal output from the forward/reverse switching lever 41, an obstacle detection signal output from the rear millimeter wave radar 61R, and a rear millimeter wave radar. Data regarding the measured distance L measured by the vehicle speed sensor 61R and the vehicle speed V detected by the vehicle speed sensor 62 are obtained.

The obstacle determining section 52 determines whether or not an obstacle exists in the backward direction of the vehicle based on the traveling direction switching signal and the obstacle detection signal acquired by the data acquiring section 51.

The distance determination unit 53 determines that the measured distance L acquired by the data acquisition unit 51 is the vehicle speed acquired by the data acquisition unit 51 when the obstacle determination unit 52 determines that an obstacle exists in the backward movement direction of the vehicle. It is determined whether the distance is shorter than a threshold distance Lth according to V. Here, the "threshold distance Lth" is the stopping distance of the vehicle body during full braking (when the brake pedal 44 is depressed to the maximum extent) according to the vehicle speed, and as shown in FIG. 5, it is proportional to the square of the vehicle speed. . The threshold distance Lth is stored in the storage unit 54, which is a memory.

Even if the obstacle determination unit 52 determines that there is an obstacle in the backward direction of the vehicle, if the vehicle is stopped in time by applying full brakes to the obstacle, there is no need for the controller 5 to control the direction of travel. Become. Therefore, in the present embodiment, the distance determination unit 53 compares the measured distance L and the threshold distance Lth, and when the measured distance L is shorter than the threshold distance Lth (L<Lth), that is, the vehicle body cannot stop even with full braking. The controller 5 performs switching control of the direction of travel only when there is a possibility that the vehicle will not arrive in time and collide with an obstacle.

When the distance determination unit 53 determines that the measured distance L is shorter than the threshold distance Lth (L<Lth), the signal output unit 55 switches the traveling direction of the vehicle body from the reverse direction to the forward direction, that is, the forward clutch 32F. A switching control signal for engaging is output to the forward electromagnetic control valve 321.

As a result, the traveling direction of the vehicle body is switched from the reverse direction to the forward direction, and at this time, braking force is generated in the vehicle body. Since this braking force is larger than the braking force generated by operating the brake pedal 44, the operator can reliably avoid a collision with an obstacle without relying on the existing braking force based on the operation of the brake pedal 44. can do.

Further, in the present embodiment, when the vehicle body stops due to the output of the switching control signal to the forward electromagnetic control valve 321, the signal output unit 55 sends a release signal to the forward electromagnetic control valve 321 to release the forward clutch 32F. Output. If the forward clutch 32F is still engaged even when the vehicle body is stopped, the wheel loader 1 will continue to move forward, so the forward clutch 32F is released and the forward/reverse switching operation is performed in a neutral state. By doing so, it is desirable to cancel the switching control of the traveling direction by the controller 5.

When the signal output unit 55 outputs a switching control signal to the forward electromagnetic control valve 321, the stop determination unit 56 determines whether the vehicle has stopped based on the vehicle speed V reacquired by the data acquisition unit 51. Determine. Specifically, when the vehicle speed V re-acquired by the data acquisition unit 51 reaches 0 (zero) (V≦0), the vehicle is in a stopped state. It is determined whether the vehicle speed V acquired again is 0 or less.

(Processing within controller 5)
Next, a specific flow of processing executed within the controller 5 will be described with reference to FIG.

FIG. 6 is a flowchart showing the flow of processing executed by the controller 5.

First, when the data acquisition unit 51 acquires the selection signal output from the changeover control selection switch 45 (step S501/ON), the obstacle determination unit 52 determines whether or not there is an obstacle in the backward movement direction of the vehicle. That is, it is determined whether the data acquisition unit 51 has acquired a traveling direction switching signal and an obstacle detection signal related to reversing (step S502).

When it is determined in step S502 that an obstacle exists in the backward direction of the vehicle, that is, when the data acquisition unit 51 acquires a traveling direction switching signal and an obstacle detection signal related to reverse movement (step S502/YES), the data acquisition unit 51 obtains the measured distance L measured by the rear millimeter wave radar 61R and the vehicle speed V detected by the vehicle speed sensor 62 (step S503).

Next, the distance determining unit 53 determines whether the measured distance L acquired in step S503 is shorter than the threshold distance Lth corresponding to the vehicle speed V acquired in step S503 (step S504).

If it is determined in step S504 that the measured distance L is shorter than the threshold distance Lth (L<Lth) (step S504/YES), the signal output unit 55 outputs a switching control signal to the forward electromagnetic control valve 321. (Step S505). Thereby, the wheel loader 1 automatically switches from reverse to forward, and braking force is generated in the vehicle body.

Subsequently, the data acquisition unit 51 acquires again the vehicle speed V detected by the vehicle speed sensor 62 (step S506). The stop determination unit 56 determines whether the vehicle speed V acquired in step S506 is 0 or less, that is, whether the vehicle is stopped (step S507).

When it is determined in step S507 that the vehicle speed V is 0 or less (V≦0), that is, the vehicle is stopped (step S507/YES), the signal output unit 55 transmits a release signal to the forward electromagnetic control valve 321. (step S508), and the processing in the controller 5 ends. On the other hand, if it is determined in step S507 that the vehicle speed V is not less than 0 (V>0), that is, the vehicle body is moving (step S507/NO), the process returns to step S506.

If the selection signal is not acquired in step S501, that is, the switching control selection switch 45 remains OFF (switching control is disabled) (step S501/NO), in step S502 there is an obstacle in the reverse direction of the vehicle. If it is determined that there is no object, that is, if the data acquisition unit 51 acquires a forward direction switching signal and an obstacle detection signal, or if the data acquisition unit 51 does not acquire an obstacle detection signal, Alternatively, if the data acquisition unit 51 acquires a traveling direction switching signal related to neutrality (step S502/NO), or if it is determined in step S504 that the measured distance L is greater than or equal to the threshold distance Lth (L≧Lth) (step In either case (S504/NO), the processing in the controller 5 ends.

The embodiments of the present invention have been described above. Note that the present invention is not limited to the embodiments described above, and includes various modifications. For example, the above-described embodiments have been described in detail to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to having all the configurations described. Furthermore, it is possible to replace a part of the configuration of this embodiment with the configuration of other embodiments, and it is also possible to add the configuration of other embodiments to the configuration of this embodiment. Furthermore, it is possible to add, delete, or replace some of the configurations of this embodiment with other configurations.

For example, in the above embodiment, the wheel loader 1 has been described as an example of one aspect of the work vehicle, but the present invention is not limited to this, and the present invention can be applied to other work vehicles such as a wheel excavator. be.

Further, the process executed within the controller 5 is a switching process that switches the traveling direction of the vehicle body to a direction opposite to the direction in which the vehicle body is traveling, at least when an obstacle is detected in the direction in which the vehicle body is traveling. Any process that outputs a control signal may be used.

1: Wheel loader (work vehicle)
5: Controller 11, 11A: Front wheel (wheel)
11, 11B: Rear wheel (wheel)
30: Engine 31: Torque converter (torque converter)
32: Transmission 32F: Forward clutch 32R: Reverse clutch 45: Changeover control selection switch (selection device)
61F: Forward millimeter wave radar (obstacle detection device)
61R: Rear millimeter wave radar (obstacle detection device)
62: Vehicle speed sensor 321: Forward forward electromagnetic control valve (electromagnetic control valve)
322: Reverse electromagnetic control valve (electromagnetic control valve)
L: Measurement distance Lth: Threshold distance

Claims (3)

A vehicle body equipped with multiple wheels,
an engine mounted on the vehicle body;
a torque converter that amplifies the torque transmitted from the engine;
A transmission that transmits the torque output from the torque converter to the plurality of wheels after cutting off or changing the speed by controlling a forward clutch and a reverse clutch with an electromagnetic control valve;
A work vehicle comprising: a controller that controls engagement and release of the forward clutch and the reverse clutch;
an obstacle detection device that detects an obstacle and measures a distance between the vehicle body and the obstacle ;
It has a vehicle speed sensor that detects vehicle speed ,
The controller includes:
A stopping distance of the vehicle body during full braking according to the vehicle speed is stored as a threshold distance,
The obstacle detection device detects the obstacle in the direction in which the vehicle body is traveling, and the distance measured by the obstacle detection device is the threshold distance according to the vehicle speed detected by the vehicle speed sensor. outputting a switching control signal to the electromagnetic control valve to switch the traveling direction of the vehicle body to a direction opposite to the direction in which the vehicle body is traveling ;
Even if the obstacle detection device detects the obstacle in the direction in which the vehicle body is traveling, it is determined that the measured distance is equal to or greater than the threshold distance according to the vehicle speed detected by the vehicle speed sensor. In this case, the switching control signal is not output to the solenoid control valve.
A work vehicle characterized by: The work vehicle according to claim 1 ,
The controller includes:
When the vehicle body comes to a stop due to the output of the switching control signal to the electromagnetic control valve, a release signal for releasing the clutch that has been engaged based on the switching control signal is output to the electromagnetic control valve. work vehicle. The work vehicle according to claim 1 ,
Selection of whether to enable switching control for switching the traveling direction of the vehicle body to the opposite direction by the controller when the obstacle detection device detects an obstacle in the direction in which the vehicle body is traveling. has a device;
The controller includes:
The switching control is enabled in the selection device , the obstacle detection device detects an obstacle in the direction in which the vehicle is traveling , and the measured distance is equal to the vehicle speed detected by the vehicle speed sensor. The working vehicle is characterized in that the switching control signal is output to the electromagnetic control valve only when it is determined that the distance is shorter than the corresponding threshold distance .

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