JP2023116919A - Wheel type work vehicle - Google Patents

Abstract

To provide a wheel type work vehicle that is able to immediately actuate steering by means of a steering operation lever when runaway occurs while preventing occurrence of steering operation unintended by an operator due to erroneous operation.SOLUTION: A wheel loader including a steering lever 34 and a setting switch 36 including a setting position for validating/invalidating an operation of the steering lever, has a controller 5 that controls actuation of steering cylinders 41, 42. When a vehicle body is in a traveling state, the controller 5 actuates the steering cylinders 41, 42 according to the operation of the steering lever 34 regardless of the setting position of the setting switch 36.SELECTED DRAWING: Figure 5

Description

The present invention relates to a wheeled working vehicle provided with a plurality of wheels.

A wheel-type work vehicle such as a wheel loader performs work while traveling on a road surface, and thus requires frequent steering operations to change the traveling direction of the vehicle. Types of steering operation devices include the general wheel-type steering operation device located in front of the driver's seat, and in recent years, with the aim of reducing operator fatigue, a comfortable steering device that allows the operator to rest his elbows on the armrest. There is a lever-type steering operation device placed near the armrest so that the steering can be operated in a relaxed posture. Depending on the specifications of the work vehicle, the driver's cab may be provided with both a wheel type and a lever type, or may be provided with either one.

A lever-type steering operation device is easier to operate than a wheel-type steering operation device. It is possible that the steering wheel will be easily tilted just by being stiff, and the steering will be actuated at a timing unexpected by the operator. Therefore, some work vehicles are equipped with a function for switching between valid and invalid operation of the operation lever in order to prevent steering operation due to erroneous operation of the operation lever.

For example, in Patent Document 1, when a steering lever switch for switching between operation and non-operation of the steering control lever is in the operating position, a seating sensor detects that the operator is not seated in the driver's seat, and the vehicle speed is detected. is less than or equal to a predetermined speed, the travel lever is in the neutral position, and the brake pedal is not depressed, the work vehicle is equipped with a control unit that disables the steering operation by the steering operation lever. there is

JP 2019-157543 A

Movement of the work vehicle includes runaway, which is unintended movement of the operator. A runaway is, for example, when the work vehicle is stopped with the parking brake applied on a steep slope, the work vehicle comes into contact with another vehicle and starts to move, or when the work vehicle is on a gentle slope. However, the operator may forget to apply the parking brake, and the work vehicle that has been stopped may begin to move. Thus, when the work vehicle runs away, the operator must immediately actuate the steering.

However, in the work vehicle disclosed in Patent Document 1, the steering lever switch is in the operating position, the seating sensor detects that the operator is seated in the driver's seat, the vehicle speed is higher than the predetermined speed, and the travel lever is in the forward or reverse position and the brake pedal is depressed. Effective operation is difficult. In particular, if the steering lever switch is in the non-operating position and a runaway occurs, the steering operation lever cannot be operated at all, so the operator cannot operate the steering with the steering operation lever.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a wheel-type work vehicle that is capable of suppressing unintentional steering operations due to erroneous operations, and that can immediately actuate the steering with a steering control lever in the event of a runaway. is to provide

In order to achieve the above object, the present invention provides a vehicle body provided with a plurality of wheels, an operator's cab provided in the vehicle body, a steering cylinder for steering the plurality of wheels, and hydraulic oil in the steering cylinder. a steering control valve for controlling the flow of hydraulic oil discharged from the hydraulic pump and supplied to the steering cylinder; a pilot pump for supplying pilot pressure oil to the steering control valve; A steering lever provided in a room for performing steering operation, an activation setting position for activating the operation of the steering lever and actuating the steering cylinder according to the operation of the steering lever, and the operation of the steering lever. a setting switch including a disabling setting position for disabling the steering cylinder to make it inoperative; an electromagnetic control valve for controlling pilot pressure oil discharged from the pilot pump and acting on the steering control valve; A wheeled work vehicle comprising a controller that controls a control valve and a vehicle speed sensor that detects a vehicle speed of the vehicle body, wherein the controller determines that the vehicle body is in a stopped state based on the vehicle speed detected by the vehicle speed sensor. When it is determined that the vehicle body is in the stopped state and the set position of the setting switch is the valid setting position, the steering cylinder is moved to the steering lever. to the electromagnetic control valve, and when it is determined that the vehicle body is in the stopped state and the set position of the setting switch is the disable set position outputs to the electromagnetic control valve a disabling signal for deactivating the operation of the steering cylinder according to the operation of the steering lever, and when it is determined that the vehicle body is in the running state, The enabling signal is output to the electromagnetic control valve.

According to the present invention, it is possible to immediately actuate the steering by the steering control lever in the event of a runaway while suppressing unintended steering operation by the operator due to an erroneous operation. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS It is an external appearance side view which shows one structural example of the wheel loader which concerns on embodiment of this invention. FIG. 4 is a top view showing the wheel loader with the steering wheel turned to the left; FIG. 3 is a perspective view of the interior of the driver's cab as viewed from the rear left side; FIG. 3 is a perspective view of the inside of the driver's cab as viewed from the front right side; 1 is a system configuration diagram showing a configuration example of a steering drive device; FIG. 3 is a functional block diagram showing functions of a controller; FIG. 4 is a flow chart showing the flow of processing executed by a controller; FIG. 4 is a state transition diagram showing state transitions of the steering drive device;

Hereinafter, as one aspect of the wheeled working vehicle according to the embodiment of the present invention, a wheel loader that performs cargo handling work of excavating, for example, earth and sand, minerals, and the like and loading them into a loading destination such as a dump truck or a hopper will be described.

(Overall Configuration of Wheel Loader 1)
First, the overall configuration of a wheel loader 1 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG.

FIG. 1 is an external side view showing one configuration example of a wheel loader 1 according to an embodiment of the present invention. FIG. 2 is a top view showing the wheel loader 1 with the steering wheel turned to the left.

The wheel loader 1 is an articulated working vehicle that is steered by bending the vehicle body near 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. A pair of left and right steering cylinders 41 and 42 are operated to bend the front frame 1A in the left and right direction with respect to the rear frame 1B.

In the following description, of the left and right directions of the vehicle body, the operator's left hand facing forward is referred to as the "left direction", and the operator's right hand side is referred to as the "right direction". FIG. 2 shows the wheel loader 1 in a state in which the steering wheel is steered to the left and the wheel loader 1 is turning left. A specific configuration of the steering operation system will be described later.

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. Of the four wheels 11, only the front wheel 11A and rear wheel 11B provided on the left side are shown in FIG. Note that there is no particular limitation on the specific number of the plurality of wheels 11 provided on the vehicle body.

A work device 2 for performing cargo handling work is attached to the front portion of the front frame 1A. The work device 2 includes a lift arm 21 attached to the front frame 1A so as to be rotatable in the vertical direction, two lift arm cylinders 22L and 22R for driving the lift arm 21, a bucket 23 mounted rotatably in the vertical direction; a bucket cylinder 24 for driving the bucket 23; and a crank 25 .

The lift arm 21 rotates upward with respect to the front frame 1A by extending the rods 220 of the two lift arm cylinders 22L and 22R, and by contracting the rods 220 of the two lift arm cylinders 22L and 22R. It rotates downward with respect to the front frame 1A. As shown in FIG. 2, the two lift arm cylinders 22L and 22R are arranged side by side with a predetermined spacing in the lateral direction of the vehicle body. In FIG. 1, the two lift arm cylinders 22L and 22R are not shown because they are located behind the left front wheel 11A.

The bucket 23 rotates upward with respect to the lift arm 21 by extending the rod 240 of the bucket cylinder 24 (tilting operation), and moves downward with respect to the lift arm 21 by contracting the rod 240 of the bucket cylinder 24. Rotate (dump operation). As a result, the bucket 23 can scoop up the object to be worked on and discharge (discharge) it to the loading destination. The bucket 23 can be replaced with various attachments such as blades, and the wheel loader 1 can perform various operations such as snow removal and dozing in addition to cargo handling operations using the bucket 23. is also possible.

The rear frame 1B includes a driver's cab 12 in which an operator rides, a machine room 13 in which various devices necessary for driving the wheel loader 1 are accommodated, and a work device 2 for keeping the balance so that the vehicle body does not tilt. A counterweight 14 of is provided. In the rear frame 1B, the operator's cab 12 is arranged at the front, the counterweight 14 is arranged at the rear, and the machine room 13 is arranged between the operator's cab 12 and the counterweight 14, respectively.

In this embodiment, the wheel loader 1 has a vehicle body controlled by a torque converter type traveling drive device. The travel drive system includes an engine 131 , a torque converter 132 connected to the output shaft of the engine 131 , and a transmission 133 connected to the output shaft of the torque converter 132 .

The driving force generated by the rotation of the engine 131 is changed by the torque converter 132 and the transmission 133, and then transmitted to the four wheels 11 via the propeller shaft 134 and the axle 135 (see FIG. 2). The wheel loader 1 travels. In FIG. 1, the engine 131, the torque converter 132, the transmission 133, and the propeller shaft 134 are indicated by dashed lines.

(Configuration inside operator's cab 12)
Next, the configuration inside the operator's cab 12 will be described with reference to FIGS. 3 and 4. FIG.

FIG. 3 is a perspective view of the interior of the operator's cab 12 as seen from the left rear. FIG. 4 is a perspective view of the interior of the driver's cab 12 as seen from the front right side.

A driver's seat 31 on which an operator sits is provided in the central portion of the driver's cab 12 . In front of the driver's seat 31, there is arranged a console 32 in which a monitor for displaying the traveling state of the vehicle body, the operating state of the work device 2, and various operation switches are arranged.

On the right side of the driver's seat 31, two work operation levers 33 are provided side by side in the left-right direction as operation devices for operating the work device 2. As shown in FIG. Each of the two working operation levers 33 is a lever that can be tilted in the front-rear direction.

One of the two work operation levers 33, one of the work operation levers 33, corresponds to a lever that operates the lift arm 21. For example, when the operator tilts one of the work operation levers 33 forward, the lift arm 21 moves forward. When the lift arm 21 rotates downward with respect to the frame 1A and is tilted backward (front), the lift arm 21 rotates upward with respect to the front frame 1A.

Of the two work operation levers 33, the other work operation lever 33 corresponds to a lever that operates the bucket 23. For example, when the operator tilts the other work operation lever 33 forward, the bucket 23 dumps. , tilts the bucket 23 backward (forward).

The operation device for operating the working device 2 does not necessarily have to be the two working operation levers 33. For example, one working operation lever 33 that can be tilted in two directions, front, rear, left, and right, can be used for lifting. Both arm 21 and bucket 23 may be operated.

A steering lever 34 is provided on the left side of the driver's seat 31 as a steering operation device for performing steering operation. In this embodiment, the steering lever 34 is an electric lever that can be tilted in the left-right direction.

For example, when the operator tilts the steering lever 34 leftward, the wheel loader 1 is steered leftward (left turn) according to the operation signal for left steering output from the steering lever 34 . On the other hand, when the operator tilts the steering lever 34 rightward, the wheel loader 1 is steered rightward (right turn) in accordance with the operation signal for right steering output from the steering lever 34 . Note that the steering lever 34 does not necessarily have to be an electric lever, and may be a mechanical lever.

A support base 35 for supporting the operator's left elbow is installed behind the steering lever 34 . The operator can operate the steering lever 34 while placing the left elbow on the support base 35 .

As shown in FIG. 4, a setting switch 36 for enabling or disabling operation of the steering lever 34 is attached to the lower front portion of the support base 35 . In this embodiment, the setting switch 36 holds a valid setting position for validating the operation of the steering lever 34, a invalid setting position for invalidating the operation of the steering lever 34, and a valid setting or a invalid setting. a holding position;

For example, when the operator pushes the setting switch 36 forward, the setting switch 36 is set to the effective setting position, and the wheel loader 1 is steered according to the operation direction and operation amount (tilt direction and tilt amount) of the steering lever 34. Operate. On the other hand, when the operator pushes the setting switch 36 toward the rear side (front side), the setting switch 36 is set to the invalid setting position, and the steering is disabled.

Since the wheel loader 1 uses a lever-type steering operation device (steering lever 34) as a steering operation device, the operator's clothing or equipment may get caught on the steering lever 34, or the operator may unintentionally touch the steering lever 34. It is easy to tilt the steering wheel just by slipping it, and it is easy to make an erroneous operation compared to a wheel-type steering operation device.

Therefore, the wheel loader 1 is provided with a setting switch 36 for enabling or disabling the operation of the steering lever 34, thereby suppressing unintended steering operation by the operator due to erroneous operation of the steering lever 34.

In addition, the setting switch 36 is in the holding position in a neutral state in which it is not pushed forward or rearward, and the setting immediately before reaching the holding position is held. The setting switch 36 only needs to include at least the enable setting position and the disable setting position, and does not necessarily need to include the holding position.

The work operation lever 33, the steering lever 34, and the setting switch 36 do not necessarily have to be arranged in the positions shown in FIGS. , may be changed according to the specifications in the operator's cab 12 .

(Structure of steering drive device 4)
Next, the configuration of the steering drive device 4 for steering the wheel loader 1 will be described with reference to FIG.

FIG. 5 is a system configuration diagram showing a configuration example of the steering drive device 4. As shown in FIG.

The steering drive device 4 includes a pair of steering cylinders 41 and 42 for steering the four wheels 11 (a pair of left and right front wheels 11A and a rear wheel 11B), and the pair of steering cylinders 41 and 42 driven by the engine 131. A hydraulic pump 44 that supplies oil, a steering control valve 45 that controls the flow (direction and flow rate) of the hydraulic oil discharged from the hydraulic pump 44 and supplied to each of the pair of steering cylinders 41 and 42, and the engine 131 A pilot pump 46 that is driven to supply pilot pressure oil to a steering control valve 45, and a pair of electromagnetic control valves 47 and 48 that control the pilot pressure oil that is discharged from the pilot pump 46 and acts on the steering control valve 45 and a hydraulic oil tank 49 that stores oil.

A pair of steering cylinders 41 and 42 are arranged side by side in the left-right direction of the vehicle body and connect the front frame 1A and the rear frame 1B. Specifically, the tip portions of the rods 41A and 42A of the pair of steering cylinders 41 and 42 are attached to the front frame 1A, and the ends on the bottom chambers 41B and 42B side are attached to the rear frame 1B. In this embodiment, of the pair of steering cylinders 41 and 42, the left one is called the "left steering cylinder 41" and the right one is called the "right steering cylinder 42".

When the rod 41A of the left steering cylinder 41 contracts and the rod 42A of the right steering cylinder 42 extends, the wheel loader 1 is steered to the left (left turn) as shown in FIG. extends and the rod 42A of the right steering cylinder 42 contracts, the steering is steered to the right (right turn).

The steering control valve 45 has a first switching position 45A for causing the wheel loader 1 to turn left, a second switching position 45B for causing the wheel loader 1 to turn right, and a neutral position 45N for causing the wheel loader 1 to go straight. These first switching position 45A, second switching position 45B, and neutral position 45N are switched to each other by movement of a spool provided inside steering control valve 45 . Note that the first switching position 45A, the second switching position 45B, and the neutral position 45N are arranged along the direction of spool movement such that the neutral position 45N is positioned between the first switching position 45A and the second switching position 45B. lined up.

In the first switching position 45A, the discharge side of the hydraulic pump 44 is connected to the rod chamber 41C of the left steering cylinder 41 and the bottom chamber 42B of the right steering cylinder 42. The rod chamber 42C and the hydraulic oil tank 49 are connected.

Therefore, when the steering control valve 45 is switched to the first switching position 45A, hydraulic fluid discharged from the hydraulic pump 44 flows into the rod chamber 41C of the left steering cylinder 41 and the bottom chamber 42B of the right steering cylinder 42, respectively. Since the rod 41A of the steering cylinder 41 contracts and the rod 42A of the right steering cylinder 42 extends, the wheel loader 1 turns left.

In the second switching position 45B, the discharge side of the hydraulic pump 44 is connected to the bottom chamber 41B of the left steering cylinder 41 and the rod chamber 42C of the right steering cylinder 42. , the bottom chamber 42B and the hydraulic oil tank 49 are connected.

Therefore, when the steering control valve 45 is switched to the second switching position 45B, hydraulic fluid discharged from the hydraulic pump 44 flows into the bottom chamber 41B of the left steering cylinder 41 and the rod chamber 42C of the right steering cylinder 42, respectively. Since the rod 41A of the steering cylinder 41 extends and the rod 42A of the right steering cylinder 42 contracts, the wheel loader 1 turns right.

At the neutral position 45N, the discharge side of the hydraulic pump 44 and the hydraulic fluid tank 49 are connected. Therefore, when the steering control valve 45 is switched to the neutral position 45N, hydraulic oil is not supplied to the left steering cylinder 41 and the right steering cylinder 42, so the wheel loader 1 goes straight without steering.

In the steering control valve 45, the pilot pressure Pi1 acting on the first pilot oil chamber 451 provided on the first switching position 45A side causes the pilot pressure Pi1 acting on the second pilot oil chamber 452 provided on the second switching position 45B side. When the pressure is greater than Pi2 (Pi1>Pi2), it switches to the first switching position 45A. On the other hand, when the pilot pressure Pi2 acting on the second pilot oil chamber 452 is higher than the pilot pressure Pi1 acting on the first pilot oil chamber 451 (Pi2>Pi1), the switch is switched to the second switching position 45B.

Further, the steering control valve 45 is such that the pilot pressure Pi1 acting on the first pilot oil chamber 451 and the pilot pressure Pi2 acting on the second pilot oil chamber 452 are the same (Pi1=Pi2) or zero (Pi1=Pi2=0). ), it switches to the neutral position 45N.

Note that even if the steering control valve 45 is not completely switched to the first switching position 45A or the second switching position 45B, the steering of the wheel loader 1 is such that the internal spool of the steering control valve 45 is on the first switching position 45A side. Alternatively, it starts to move to the second switching position 45B side and operates when the hydraulic oil discharged from the hydraulic pump 44 starts to be supplied to the pair of steering cylinders 41 and 42 .

A pilot pressure Pi acting on the first pilot oil chamber 451 and a pilot pressure Pi2 acting on the second pilot oil chamber 452 are controlled by a pair of electromagnetic control valves 47 and 48 . In the present embodiment, the one of the pair of electromagnetic control valves 47 and 48 that controls the pilot pressure Pi acting on the first pilot oil chamber 451 is called the "first electromagnetic control valve 47", and the one that controls the pilot pressure Pi acting on the first pilot oil chamber 451. The one that controls the pilot pressure Pi2 acting on the valve 452 is called the "second electromagnetic control valve 48". The first electromagnetic control valve 47 and the second electromagnetic control valve 48 are controlled according to command signals output from the controller 5 respectively.

The controller 5 includes a steering lever 34, a setting switch 36, a vehicle speed sensor 60 mounted on the transmission 133 (indicated by dashed lines in FIGS. 1 and 5) to detect the vehicle speed, a first electromagnetic control valve 47, and a second electromagnetic control valve. 48 are electrically connected.

An operation signal output from the steering lever 34, a setting signal output from the setting switch 36, and a vehicle speed signal output from the vehicle speed sensor 60 are input to the controller 5, respectively.

The operation signal output from the steering lever 34 is a signal based on the operator's operation, and includes data relating to the operation direction and operation amount (tilting direction and tilting amount) of the steering lever 34 . If the steering lever 34 is a mechanical lever, the controller 5 receives data output from an operating state sensor that detects the operating direction and amount of the steering lever 34, that is, the operating state of the steering lever 34. .

The setting signal output from the setting switch 36 is set to a valid setting position ("ON" shown in FIG. ), and an invalidation setting signal relating to an invalidation setting position ("LOCK" shown in FIG. 5) that invalidates the operation of the steering lever 34 and deactivates the pair of steering cylinders 41 and 42. ,including.

A vehicle speed signal output from the vehicle speed sensor 60 is a data signal related to the vehicle speed detected by the vehicle speed sensor 60 . For the vehicle speed sensor 60, for example, a speed sensor for detecting the speed of the propeller shaft may be used.

The controller 5 operates the first electromagnetic control valve 47 and the second electromagnetic control valve 47 based on these input signals, that is, the operation signal from the steering lever 34, the setting signal from the setting switch 36, and the vehicle speed signal from the vehicle speed sensor 60. 48 to generate a command signal.

(Configuration of controller 5)
Next, the configuration of the controller 5 will be described with reference to FIG.

FIG. 6 is a functional block diagram showing functions of the controller 5. As shown in FIG.

The controller 5 is configured by connecting a CPU, RAM, ROM, HDD, input I/F, and output I/F to each other via a bus. Various operating devices such as the steering lever 34 and the setting switch 36 and sensors such as the vehicle speed sensor 60 are connected to the input I/F. It is connected to the.

In such a hardware configuration, a control program (software) stored in a recording medium such as a ROM, HDD, or optical disc is read out by the CPU, expanded on the RAM, and executed by executing the expanded control program. The program and hardware work together to implement the functions of the controller 5 .

In this embodiment, the controller 5 is described as a computer configured by a combination of software and hardware. An integrated circuit that implements the functions of the executed control program may be used.

The controller 5 includes a data acquisition section 51 , a determination section 52 , an elapsed time measurement section 53 , a command signal output section 54 and a storage section 55 .

The data acquisition unit 51 acquires an operation signal output from the steering lever 34, a setting signal output from the setting switch 36, and data regarding the vehicle speed detected by the vehicle speed sensor 60 (vehicle speed signal).

The determination unit 52 includes a setting determination unit 52A, a vehicle body state determination unit 52B, and a lever position determination unit 52C.

Based on the setting signal acquired by the data acquisition unit 51, the setting determination unit 52A determines whether the setting position of the setting switch 36 is the enable setting position or the disable setting position. In other words, the setting determination unit 52A determines whether the setting signal acquired by the data acquisition unit 51 is the activation setting signal or the invalidation setting signal.

Based on the vehicle speed acquired by the data acquisition unit 51, the vehicle body state determination unit 52B determines whether the vehicle body is in a running state. Note that the vehicle body state determination unit 52B does not determine that the vehicle body is in a stopped state only when the vehicle speed detected by the vehicle speed sensor 60 coincides with 0 (zero). determines whether or not the vehicle body is in a stopped state. A determination threshold value for the running state (or stopped state) of the vehicle body is stored in advance in the storage unit 55 .

Based on the operation signal acquired by the data acquisition unit 51, the lever position determination unit 52C determines the operating state (tilting direction and amount) of the steering lever 34, that is, to what position the steering lever 34 is tilted by the operator. do. In particular, the lever position determination unit 52C determines whether the steering lever 34 is in the neutral position or operated to the maximum tilt position.

Here, the "neutral position" of the steering lever 34 is a position where the supply of hydraulic oil from the hydraulic pump 44 to the pair of steering cylinders 41, 42 is stopped. The "maximum tilt position" of the steering lever 34 includes the "maximum left tilt position" and the "maximum right tilt position". It is the position where the amount is the preset maximum amount.

More specifically, the "left maximum tilt position" is a preset maximum amount of hydraulic oil supplied from the hydraulic pump 44 to the rod chamber 41C of the left steering cylinder 41 and the bottom chamber 42B of the right steering cylinder 42. is the position where That is, when the operator wishes to turn the steering wheel to the left as much as possible, the operator operates the steering lever 34 to the maximum left tilt position.

The "right maximum tilt position" is a position where the amount of hydraulic oil supplied from the hydraulic pump 44 to the bottom chamber 41B of the left steering cylinder 41 and the rod chamber 42C of the right steering cylinder 42 is set to a preset maximum amount. be. That is, when the operator wants to turn the steering wheel to the right as much as possible, the operator operates the steering lever 34 to the maximum right tilt position.

Note that the "maximum tilt position" does not necessarily have to be a position where the maximum amount of hydraulic oil that can be supplied from the hydraulic pump 44 to the pair of steering cylinders 41 and 42 is obtained. The maximum amount of hydraulic oil to be supplied to 41 and 42 may be set arbitrarily (preset maximum amount).

The elapsed time measurement unit 53 measures the time T that has elapsed since the vehicle body state determination unit 52B determined that the vehicle has stopped, and determines whether the measured time T has passed a predetermined time Tth. This "predetermined time Tth" is an arbitrary time (for example, less than 10 seconds) pre-stored in the storage unit 55, and the vehicle body is restarted after the vehicle body state determination unit 52B determines that the vehicle body is stopped. It is set at a time that considers the possibility of starting to move.

The command signal output unit 54 outputs an enable signal for operating the pair of steering cylinders 41 and 42 according to the operation of the steering lever 34 or a pair of steering cylinders according to the operation of the steering lever 34 according to the determination result of the determination unit 52 . Disabling signals for deactivating the cylinders 41 and 42 are output to the first electromagnetic control valve 47 and the second electromagnetic control valve 48, respectively.

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

FIG. 7 is a flow chart showing the flow of processing executed by the controller 5. As shown in FIG.

In the controller 5, the setting determination unit 52A first determines whether the setting position of the setting switch 36 is the enable setting position or the disable setting position based on the setting signal acquired by the data acquisition unit 51. (step S501). That is, in step S501, it is determined whether the setting switch 36 is set to a valid setting or an invalid setting.

If it is determined in step S501 that the setting switch 36 is set to the disable setting position (step S501/disable), then the setting determination unit 52A determines that the setting switch 36 is set to the enable setting position. It is determined whether or not the setting switch 36 has been switched, that is, whether or not the setting switch 36 has not been operated to enable setting and remains in the disable setting position (step S502).

If it is determined in step S502 that the set position of the setting switch 36 has not been switched to the enable setting position (it remains in the disable setting position) (step S502/YES), the vehicle body state determination unit 52B acquires data. Based on the vehicle speed signal acquired by the unit 51, it is determined whether or not the vehicle body is moving, that is, whether or not the vehicle is in a running state (step S503).

If it is determined in step S503 that the vehicle body is moving (step S503/YES), the lever position determination unit 52C determines whether the steering lever 34 is in the neutral position or is operated to the maximum tilt position. (step S504).

On the other hand, if it is determined in step S502 that the vehicle body is not moving, that is, that the vehicle body is in a stopped state (step S503/NO), the process does not proceed to step S504 until the vehicle body starts moving (enters a running state).

If it is determined in step S504 that the steering lever 34 is in the neutral position or has been operated to the maximum tilt position (step S504/YES), the command signal output unit 54 controls the first electromagnetic control valve 47 and the second electromagnetic control valve. An activation signal is output to each of the valves 48 (step S505). That is, when the steering lever 34 is in the neutral position or is operated to the maximum tilt position, the controller 5 controls the first electromagnetic control valve 47 and the first electromagnetic control valve 47 even if the setting switch 36 is in the disable setting position. 2 Outputs an enabling signal to each of the electromagnetic control valves 48 .

On the other hand, if it is determined in step S504 that the steering lever 34 is not in the neutral position and the operation to the maximum tilt position is not performed (step S504/NO), the steering lever 34 returns to the neutral position, or , the process does not proceed to step S505 until it is operated to the maximum tilt position.

Next, based on the setting signal acquired by the data acquisition unit 51, the setting determination unit 52A determines whether or not the setting switch 36 has been switched to the activation setting position. is determined (step S506).

If it is determined in step S506 that the setting switch 36 has switched to the activation setting position (step S506/YES), the command signal output unit 54 is activated for the first electromagnetic control valve 47 and the second electromagnetic control valve 48. and continuously output the conversion signals (step S507).

Subsequently, based on the setting signal acquired by the data acquisition unit 51, the setting determination unit 52A determines whether or not the setting position of the setting switch 36 has been switched to the invalidation setting position. It is determined whether or not a setting operation has been performed (step S508).

If it is determined in step S508 that the setting position of the setting switch 36 has been switched to the invalidation setting position (step S508/YES), the vehicle body state determination unit 52B determines the vehicle speed based on the vehicle speed signal acquired by the data acquisition unit 51. has stopped (step S509).

On the other hand, if it is determined in step S508 that the setting position of the setting switch 36 has not been switched to the invalidation setting position, that is, that it remains in the validating setting position (step S508/NO), the process returns to step S507. , the command signal output unit 54 continues to output the enable signal to the first electromagnetic control valve 47 and the second electromagnetic control valve 48 .

Next, when it is determined in step S509 that the vehicle body has stopped (step S509/YES), the elapsed time measuring unit 53 measures the time T after it is determined that the vehicle body has stopped. It is determined whether or not Tth has passed (step S510).

On the other hand, if it is not determined in step S509 that the vehicle body has stopped, that is, if it is determined that the vehicle body is still running (step S509/NO), the process does not proceed to step S510 until the vehicle body stops.

Subsequently, when it is determined in step S510 that the measured time T has passed the predetermined time Tth (T≧Tth) (step S510/YES), the command signal output unit 54 controls the first electromagnetic control valve 47 and the second electromagnetic An invalidation signal is output to each of the control valves 48 (step S511), and the processing in the controller 5 ends.

On the other hand, if it is determined in step S510 that the measured time T has not passed the predetermined time Tth (T<Tth) (step S510/NO), the measured time T passes the predetermined time Tth (T≧Tth). Do not proceed to step S511.

If it is determined in step S506 that the set position of the setting switch 36 has not been switched to the enable setting position, that is, if it is determined that the setting switch 36 is still in the disable setting position (step S506/NO), the process proceeds to step S509. , the vehicle body state determination unit 52B determines the state of the vehicle body.

Further, when it is determined in step S501 that the setting position of the setting switch 36 is the activation setting position (step S501/validation), the process proceeds to step S508, and the setting determination unit 52A instructs the setting switch 36 to It is determined whether or not an invalidation setting operation has been performed.

If it is determined in step S502 that the setting position of the setting switch 36 has been switched to the activation setting position, that is, if it is determined that the activation setting operation has been performed on the setting switch 36 (step S502/NO), the lever position is determined. The unit 52C determines whether or not the steering lever 34 is in the neutral position (step S512).

When it is determined in step S512 that the steering lever 34 is in the neutral position (step S512/YES), the command signal output unit 54 outputs an enabling signal to the first electromagnetic control valve 47 and the second electromagnetic control valve 48. Each is output (step S513), and the process proceeds to step S508.

On the other hand, when it is determined in step S512 that the steering lever 34 is not in the neutral position (step S512/NO), the process does not proceed to step S513 until the steering lever 34 is operated to the neutral position.

(State transition of steering drive device 4)
Next, state transition of the steering drive device 4 accompanying processing by the controller 5 will be described with reference to FIGS. 7 and 8. FIG.

FIG. 8 is a state transition diagram showing state transitions of the steering drive device 4 .

First, when the vehicle body is in a stopped state and the set position of the setting switch 36 is the disable setting position (step S501/disable→step S502/YES), the steering drive device 4 enters the disable state ST1 in which the steering does not operate. It is in.

When the steering drive device 4 is in the disabled state ST1, it is detected that the vehicle body is in the running state and the steering lever 34 is in the neutral position or is operated to the maximum tilt position (for example, the steering lever 34 Based on the output operation signal, the operation amount operated to the maximum tilt position is detected), the controller 5 sends an enable signal to the first electromagnetic control valve 47 and the second electromagnetic control valve 48, respectively. Output (step S503/YES→step S504/YES→step S505). As a result, the steering drive device 4 transits to the temporary enabled state ST2 in which the steering operates regardless of the set position of the setting switch 36 (arrow X1 shown in FIG. 8).

As described above, even if the wheel loader 1 is in the running state (occurrence of runaway) when the steering drive device 4 is in the invalid state ST1, the steering lever 34 is in the neutral position or is operated to the maximum tilt position. When the controller 5 determines that the steering drive device 4 has been activated, the steering drive device 4 transitions to the temporary activated state ST2. , the steering can be operated by the steering lever 34 immediately.

Thus, in the wheel loader 1, by providing the setting switch 36, erroneous operation of the steering lever 34 can be suppressed, and steering can be actuated immediately by the steering lever 34 when a runaway occurs.

In the present embodiment, one of the conditions for the steering drive device 4 to transition from the disabled state ST1 to the temporarily enabled state ST2 (transition condition from the disabled state ST1 to the temporarily enabled state ST2) is that the vehicle body is in the running state. In addition, the steering lever 34 is in the neutral position or is operated to the maximum tilt position (detection of the amount of operation of the steering lever 34 to the maximum tilt position). The condition for transition from the disabled state ST1 to the temporarily enabled state ST2 may be at least that the vehicle body is in a running state (a runaway has occurred).

However, by including the fact that the steering lever 34 is in the neutral position in the transition condition from the disabled state ST1 to the temporarily enabled state ST2, when the steering drive device 4 transitions to the temporarily enabled state ST2, the steering is suddenly actuated. It is possible to suppress the situation such as collapse.

Further, by including the fact that the steering lever 34 is operated to the maximum tilting position (that the operation amount of the steering lever 34 being operated to the maximum tilting position is detected) in the transition condition from the disabled state ST1 to the temporarily enabled state ST2, the runaway is prevented. Since the operator's intention to actuate the steering can be confirmed in response to the occurrence, the controller 5 can more accurately determine that the runaway has occurred.

Subsequently, when the steering drive device 4 is in the temporarily enabled state ST2, when the set position of the setting switch 36 is switched to the enabled set position (step S506/YES), the steering drive device 4 is released from the temporarily enabled state ST2. A transition is made to a valid state ST3 in which steering is actuated (arrow X2 shown in FIG. 8).

Next, when the steering drive device 4 is in the enabled state ST3 and the set position of the setting switch 36 is switched to the disabled set position (step S508/YES), the controller 5 keeps the vehicle body stopped for a predetermined time Tth. After a lapse of time, disable signals are output to the first electromagnetic control valve 47 and the second electromagnetic control valve 48 (step S509/YES→step S510/YES→step S511).

That is, when the steering drive device 4 is in the valid state ST3, the setting switch 36 is switched from the valid setting position to the invalid setting position only, and the steering drive device 4 does not transit to the invalid state ST1, but the temporary valid state. It becomes ST2 (arrow Y1 shown in FIG. 8). As a result, the operator can immediately operate the steering with the steering lever 34 even if the setting switch 36 is set to the disable setting position and the vehicle runs away.

When the steering drive device 4 is in the temporarily enabled state ST2, the steering drive device 4 transitions from the temporarily enabled state ST2 to the disabled state ST1 (arrow Y2 shown in FIG. 8) after a predetermined time Tth has elapsed since the vehicle body stopped. That is, when the controller 5 determines that the vehicle body is stopped and there is no possibility of returning to the running state, the steering drive device 4 is set to the disabled state ST1 to reliably prevent erroneous operation of the steering lever 34. be able to.

In this embodiment, the condition for the steering drive device 4 to transition from the temporarily enabled state ST2 to the disabled state ST1 (transition condition from the temporarily enabled state ST2 to the disabled state ST1) is that the predetermined time Tth has elapsed since the vehicle stopped. However, it is not limited to this, and at least stopping of the vehicle body may be a transition condition from the temporary valid state ST2 to the invalid state ST1. However, by including the lapse of a predetermined time Tth after the vehicle has stopped in the transition condition from the temporarily valid state ST2 to the invalid state ST1, the steering lever 34 can be immediately operated when the vehicle starts to move immediately after stopping. Steering can be activated.

Further, when the steering drive device 4 is in the disabled state ST1, the setting switch 36 is switched to the enabled setting position, and the steering lever 34 is operated to the neutral position (for example, output from the steering lever 34 is Based on the operation signal, the operation amount operated to the neutral position is detected), the controller 5 outputs enable signals to the first electromagnetic control valve 47 and the second electromagnetic control valve 48 (step S502/NO→step S512/YES→step S513). As a result, the steering drive device 4 transitions from the disabled state ST1 to the enabled state ST3 (arrow X3 shown in FIG. 8).

In this way, by including the fact that the steering lever 34 is in the neutral position in the condition for the steering drive device 4 to transition from the disabled state ST1 to the enabled state ST3, the steering wheel is operated when the steering drive device 4 transitions to the enabled state ST3. It is possible to suppress a situation such as sudden operation.

The embodiments of the present invention have been described above. In addition, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Further, part of the configuration of this embodiment can be replaced with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of this embodiment. Furthermore, it is possible to add, delete, or replace a part of the configuration of this embodiment with another configuration.

For example, in the above embodiment, the wheel loader 1 was specifically described as an example of a wheeled work vehicle, but the wheel loader 1 is not necessarily the wheeled work vehicle, and a wheeled work vehicle provided with a plurality of wheels. Any work vehicle other than the wheel loader 1 may be used as long as it is a work vehicle.

Further, in the above-described embodiment, the steering lever 34 is an electric operation lever, so that pressure oil discharged from the pilot pump 46 is reduced in pressure by the first electromagnetic control valve 47 and the second electromagnetic control valve 48. However, if the steering lever 34 is a mechanical control lever, the pilot pressure oil is generated by reducing the pressure of the pressure oil discharged from the pilot pump 46 by the pilot valve. . In this case, the first electromagnetic control valve 47 and the second electromagnetic control valve 48 control whether or not the pilot pressure oil generated by the pilot valve acts on the steering control valve 45 .

1: Wheel loader (wheel type work vehicle)
5: Controllers 11, 11A, 11B: Wheels 12: Cab 34: Steering lever 36: Setting switch 41: Left steering cylinder (steering cylinder)
42: Right steering cylinder (steering cylinder)
44: Hydraulic pump 45: Steering control valve 46: Pilot pump 47: First electromagnetic control valve (electromagnetic control valve)
48: Second electromagnetic control valve (electromagnetic control valve)
60: Vehicle speed sensor

Claims (3)

a vehicle body provided with a plurality of wheels;
a driver's cab provided in the vehicle body;
a steering cylinder that steers the plurality of wheels;
a hydraulic pump that supplies hydraulic fluid to the steering cylinder;
a steering control valve for controlling the flow of hydraulic fluid discharged from the hydraulic pump and supplied to the steering cylinder;
a pilot pump that supplies pilot pressure oil to the steering control valve;
a steering lever provided in the driver's cab for steering operation;
A valid setting position for validating the operation of the steering lever and actuating the steering cylinder according to the operation of the steering lever, and a invalid setting position for invalidating the operation of the steering lever and deactivating the steering cylinder. and a configuration switch including
an electromagnetic control valve that controls pilot pressure oil that is discharged from the pilot pump and acts on the steering control valve;
a controller that controls the electromagnetic control valve;
a vehicle speed sensor that detects the vehicle speed of the vehicle body;
In a wheeled work vehicle comprising
The controller is
determining whether the vehicle body is in a stopped state or a running state based on the vehicle speed detected by the vehicle speed sensor;
When it is determined that the vehicle body is in the stopped state and the setting position of the setting switch is the activation setting position, the activation signal for operating the steering cylinder in accordance with the operation of the steering lever is output. output to the solenoid control valve,
When it is determined that the vehicle body is in the stopped state and the set position of the setting switch is the disabling setting position, the operation of the steering cylinder corresponding to the operation of the steering lever is disabled. outputting a conversion signal to the electromagnetic control valve;
A wheeled work vehicle, wherein the activation signal is output to the electromagnetic control valve when it is determined that the vehicle body is in the running state. In the wheeled work vehicle according to claim 1,
The controller is
It is determined that the vehicle body is in the running state, the set position of the setting switch is the disabling set position, and the operating state of the steering lever indicates that hydraulic oil is flowing from the hydraulic pump to the steering cylinder. If it is in neutral position to stop feeding,
or
It is determined that the vehicle body is in the running state, the set position of the setting switch is the disabling set position, and the operating state of the steering lever indicates that hydraulic oil is flowing from the hydraulic pump to the steering cylinder. When it is the maximum tilt position where the supply amount is the preset maximum amount,
outputting the enabling signal to the electromagnetic control valve;
It is determined that the vehicle body is in the running state, the set position of the setting switch is the disabling set position, and the operation state of the steering lever is different from the neutral position and the maximum tilt position. If the state is
A wheeled work vehicle, wherein the disabling signal is output to the electromagnetic control valve. In the wheeled work vehicle according to claim 2,
The controller is
A state in which the enabling signal is output to the electromagnetic control valve, it is determined that the vehicle body is in the stopped state, and the set position of the setting switch is set to the disable set position for a predetermined time. If you do
A wheeled work vehicle, wherein the disabling signal is output to the electromagnetic control valve.

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