JP7797971B2 - Work vehicles - Google Patents

Description

The present invention relates to work vehicles such as tractors.

Conventionally, the steering load on work vehicles is significantly different when driving on public roads and when driving for work purposes. Therefore, inexperienced drivers may steer the vehicle when driving on public roads in the same way as when driving for work purposes, causing the vehicle to sway significantly from side to side.

Therefore, a known work vehicle is equipped with a mode selector switch that switches between work mode and non-work mode, and when non-work mode is selected, the steering speed of the steered wheels relative to the steering operation speed is set slower than when work mode is selected (Prior Document 1).

This type of work vehicle can reduce wobbling when not working.

Japanese Patent Application Publication No. 10-109660

However, in work vehicles, it may be desirable to vary the steering load even while work is in progress, but the above technology does not allow the steering load to be changed depending on the situation during work travel.

The objective of the present invention is to provide a work vehicle that can appropriately change the steering load depending on the situation while traveling for work.

The present invention provides
A running vehicle body,
a steering wheel for changing the direction of travel of the traveling vehicle body;
a steering wheel for operating the steering wheels;
a steering sensor for detecting an operation of the steering wheel;
a control unit for changing the operation load of the steering wheel,
a hydraulic power steering mechanism is used to operate the steering wheels with the steering wheel,
The hydraulic power steering mechanism includes a hydraulic device that sends hydraulic oil to a steering wheel drive hydraulic cylinder in response to rotation of the steering wheel,
When working in the field,
When the control unit determines that the steering wheel has been turned based on the detection value of the steering sensor, it adjusts the variable throttle between the hydraulic device and the steering wheel drive hydraulic cylinder to reduce the operating load of the steering wheel compared to when the turning operation is not detected,
The steering sensor detects an angular velocity of the steering wheel operation, and the control unit determines that the steering wheel is being turned when the angular velocity exceeds a predetermined value.
When the steering wheel operation angle is equal to or greater than a predetermined effective angle, the angle of the steering wheels begins to change,
When the control unit determines that the steering wheel has been turned within a range less than the effective angle, the control unit reduces the operating load of the steering wheel compared to when the turning operation is not detected,
This work vehicle is characterized in that when the control unit determines that the steering wheel has been turned within a range equal to or greater than the effective angle, it gradually reduces the steering wheel operating load in stages or continuously in accordance with predetermined rules compared to when the turning operation is not detected.
The first invention related to the present invention is:
A running vehicle body,
a steering wheel for changing the direction of travel of the traveling vehicle body;
a steering wheel for operating the steering wheels;
a steering sensor for detecting an operation of the steering wheel;
a control unit for changing the operation load of the steering wheel,
When working in the field,
This work vehicle is characterized in that when the control unit determines that the steering wheel has been turned based on the detection value of the steering sensor, it reduces the operating load of the steering wheel compared to when the turning operation is not detected.

The second invention related to the present invention is:
This is a work vehicle of a first invention related to the present invention, in which the steering sensor detects the angular velocity of the steering wheel operation, and the control unit determines that a turning operation is being performed when the angular velocity exceeds a predetermined value that has been set in advance.

The third invention related to the present invention is:
This is a work vehicle of a second invention related to the present invention, in which the angle of the steering wheels begins to change when the operating angle of the steering wheel becomes equal to or greater than a predetermined effective angle, and the control unit determines whether or not a turning operation has occurred within a range less than the effective angle, and does not determine whether or not a turning operation has occurred within a range equal to or greater than the effective angle .

The fourth invention related to the present invention is:
When the steering wheel operation angle is equal to or greater than a predetermined effective angle, the angle of the steering wheels begins to change,
When the control unit determines that the steering wheel has been turned within a range less than the effective angle, the control unit reduces the operating load of the steering wheel compared to when the turning operation is not detected,
This is a work vehicle of a second invention related to the present invention, in which when the control unit determines that the steering wheel has been turned within a range equal to or greater than the effective angle, it gradually reduces the steering wheel operating load in stages or continuously in accordance with predetermined rules compared to when the turning operation is not detected.

The fifth invention related to the present invention is:
a hydraulic power steering mechanism is used to operate the steering wheels with the steering wheel,
In a work vehicle of a first invention related to the present invention , the control unit changes the operating load of the steering wheel by controlling a hydraulic circuit of the hydraulic power steering mechanism.

The sixth invention related to the present invention is:
an electric power steering mechanism using an electric motor is used to operate the steering wheels with the steering wheel,
In a work vehicle according to a first aspect of the present invention , the control unit changes the operating load of the steering wheel by controlling the electric power steering mechanism.

This invention reduces the burden on the driver by reducing the steering load when turning, which requires a large amount of steering. It also makes it possible to appropriately change the steering load, such as by making the steering load heavier when not turning, such as when traveling straight, compared to when turning, thereby ensuring stability when traveling straight. Furthermore, since it is possible to determine whether a turning operation is being performed almost immediately after the start of the operation, rather than judging by the steering angle, the driver can operate the steering wheel without any discomfort. Furthermore, once the steering wheels have rotated and the vehicle body has begun to turn, any change in steering wheel load while the vehicle body is turning is made gradually, which has the advantage of reducing the sense of discomfort.
According to the first invention related to the present invention , the steering wheel operation load can be reduced when turning, allowing for turning with less force. The burden on the driver can be reduced by reducing the operation load when turning, which requires a large amount of operation. The steering operation load can be appropriately changed when not turning, such as when going straight, by making the operation load heavier than when turning, thereby ensuring stability when going straight.

According to a second invention related to the present invention , when the operation angle is detected to determine whether or not a turning operation is being performed, a certain degree of angle is required to determine whether or not a turning operation is being performed, but in that case, the load may change during the operation, which tends to cause an uncomfortable feeling in the operation.In contrast, if the determination is made based on the angular velocity, it is possible to determine whether or not a turning operation is being performed almost immediately after the start of the operation, rather than determining based on the operation angle, so the driver can perform the operation without any discomfort.

According to a third invention related to the present invention , based on the premise that the steering wheel will not rotate unless the steering wheel is rotated by a predetermined effective angle or more (play range), the steering wheel operating load is changed before the angle of the steering wheel begins to change, and not after the steering wheel has rotated and the vehicle body has begun to turn, thereby preventing a phenomenon in which the steering wheel load is changed while the vehicle body is turning, causing an uncomfortable feeling.

The fourth invention related to the present invention has the advantage that, based on the premise of a mechanism (play range) in which the steering wheel will not rotate unless the steering wheel is rotated by a predetermined effective angle or more, once the steering wheel has rotated and the vehicle body has started to turn, even if the load on the steering wheel is changed while the vehicle body is turning, it is done gradually, so there is little sense of discomfort.

According to a fifth aspect of the present invention , a hydraulic power steering mechanism can be used.

According to a sixth aspect of the present invention , an electric power steering mechanism can be used.

1 is a side view of a tractor according to an embodiment of the present invention; Plan of the field on which the tractor runs Diagram of the tractor's main components Plan view of the steering wheel of the tractor Control configuration diagram of the tractor A diagram showing the hydraulic power steering mechanism (neutral state) that is the control target of the control unit of the tractor. The figure shows the hydraulic power steering mechanism (left turning state) that is the control target of the control unit of the tractor. The figure shows the hydraulic power steering mechanism (right turning state) that is the control target of the control unit of the tractor. A diagram showing the electric power steering mechanism that is controlled by the control unit of the tractor.

The following describes in detail an embodiment of the present invention with reference to the drawings.

Figure 1 shows a tractor as an example of a work vehicle according to an embodiment of the present invention. First, the overall configuration of the tractor 1 will be described with reference to Figure 1.

The work vehicle, tractor 1, is an agricultural tractor used to perform work in fields and the like, and is driven by a driver (also called an operator) who drives the tractor around the field to perform specified tasks.

Furthermore, in the following, the "forward/rearward direction" refers to the direction of travel of the tractor 1 when traveling straight, with the forward side of the traveling direction defined as "front" and the rear side defined as "rear." The traveling direction of the tractor 1 when traveling straight is the direction from the driver's seat 8 (described below) toward the steering wheel (steering device) 9 (see Figure 1).

The left-right direction is the direction that is horizontally perpendicular to the front-to-rear direction. Hereinafter, left and right are defined as facing forward. In other words, when the operator of the tractor 1 (also referred to as the "operator") is seated in the operator's seat 8 and facing forward, the left-hand side is the "left" and the right-hand side is the "right."

The up-down direction refers to the vertical direction. The front-to-back, left-to-right, and up-down directions are perpendicular to one another. Note that each direction is defined for the convenience of explanation, and the present invention is not limited to these directions. In the following, the tractor 1 may be referred to as the "machine body" or "vehicle body."

As shown in Figure 1, the tractor 1 comprises a running body 2 and a work implement link mechanism at its rear. The running body 2 comprises a body frame 3, front wheels 4, rear wheels 5, a hood 6, an engine E, a steering unit 7, and a transmission case 10. The body frame 3 is the main frame of the running body 2.

The front wheels 4 are a pair of left and right wheels that are primarily used for steering (steering wheels 4). The rear wheels 5 are a pair of left and right wheels that are primarily used for driving (driving wheels 5). The tractor 1 may be configured to be switchable between two-wheel drive (2WD), in which the rear wheels 5 are driven, and four-wheel drive (4WD), in which both the front wheels 4 and rear wheels 5 are driven. In this case, both the front wheels 4 and rear wheels 5 are driven wheels.

The hood 6 is mounted at the front of the vehicle body 2 so that it can be opened and closed freely. The hood 6 can be rotated (opened and closed) in the vertical direction with its rear as the center of rotation. When closed, the hood 6 covers the engine E mounted on the vehicle frame 3. The engine E is the driving source of the tractor 1 and is a thermal engine such as a diesel engine or gasoline engine. Note that the hood 6 may also rotate around its front.

The control unit 7 is located on top of the vehicle body 2 and includes a driver's seat 8 and a steering wheel (steering device) 9. The driver's seat 8 is the driver's seat. The steering wheel 9 is operated by the driver when steering the front wheels 4. The control unit 7 also includes a display unit (meter panel) 9a in front of the steering wheel 9 that displays various information.

The control unit 7 also includes various operating levers such as a forward/reverse lever, accelerator lever, main shift lever, and auxiliary shift lever, as well as various operating pedals such as an accelerator pedal, brake pedal, and clutch pedal.

Note that 10 is the transmission case, 12 is the towing unit, 20 is the control unit, 30 is the GNSS device, S is the navigation satellite, and Vs is a sensor attached to the body frame 3 that detects the speed of the tractor 1.

Figure 2 shows such a tractor 1 working in field H, performing work in a straight-line process where it travels back and forth in a straight line in the center, a turning process where it turns between the straight-line processes, and a circular process where it is located on the periphery.

Figure 3 is a diagram of the control unit 20. Reference numeral 21 denotes a steering sensor, which in this embodiment detects the angular velocity of the rotation angle of the steering wheel 9. The detected value of the steering sensor 21 is sent to the judgment unit 20a of the control unit 20. The control unit 20 is also provided with a numerical value setting unit 20b, which is constantly input to the judgment unit 20a. In this embodiment, a predetermined angular velocity value is preset in the numerical value setting unit 20b. The predetermined angular velocity value is set to a value that, when reached, ensures that it can be determined that the steering wheel 9 has been turned by the driver's steering operation. It also serves the function of distinguishing between a weak turn while driving straight ahead and a strong turn near a bank.

As a result, the judgment unit 20a compares the value of the detection signal input from the steering sensor 21 with the value set in the value setting unit 20b, and if the two match, it determines that the steering wheel 9 has been turned.

In this way, when the judgment unit 20a detects a turning operation, it issues an instruction to make the operating load of the steering wheel 9 lighter than when the turning operation is not detected. In accordance with this instruction, the operating load of the steering wheel 9 is made lighter than its previous state using various methods, as described below.

Note that the detection of the angular velocity of the steering sensor 21 and the determination of a turning operation based on that detection may be performed by determining whether or not a turning operation is occurring within a range less than the effective angle, and not determining whether or not a turning operation is occurring within a range equal to or greater than the effective angle. θ in Figure 4 indicates this effective angle.

In other words, based on the premise that the steered wheels 4,4 will not rotate unless the steering wheel 9 is rotated by a predetermined effective angle θ or more (the so-called play range), the operating load on the steering wheel 9 is changed before the angle of the steered wheels 4,4 begins to change, and not after the steered wheels 4,4 have rotated and the vehicle body 2 has begun to turn. This prevents the phenomenon of a change in the load on the steering wheel 9 while the vehicle body 2 is turning, causing discomfort.

As a modified example, if the angular velocity does not reach the predetermined value by the time the effective angle θ is reached, and then the angular velocity reaches the predetermined value, the steering wheel 9 operation load may be reduced. However, rather than reducing the load suddenly, the load may be gradually reduced in stages or continuously according to predetermined rules. This is to reduce the sense of discomfort.

Next, an embodiment will be described in which a characteristic other than the angular velocity is detected by the steering sensor 21 to determine that the steering wheel 9 has been or will be turned (see FIG. 5).
In this example, the steering sensor 21 detects the torque applied to the steering wheel 9 and determines that a turning operation has been performed. For example, a strain sensor that detects the twist of the shaft of the steering wheel 9 is used.

At this time, the steering load may be changed in stages according to the magnitude of the torque.
b. This is an example in which the steering sensor 21 detects the turning speed of the steering wheel 9, that is, the circumferential speed, and determines that a turning operation has been performed.

If a circumferential speed greater than a predetermined speed is detected, it is determined that a turning operation has been performed.

However, it is also possible to make such judgments within the scope of play and not make judgments beyond that.

Not making a turning judgment when the play is outside this range can also be applied to other embodiments.

Alternatively, instead of detecting the angular velocity, angular acceleration may be detected to determine whether the vehicle is turning.

An embodiment in which turning is detected by a device other than a steering sensor will be described below (see FIG. 5).
a. The steering angle sensor 52 detects the steering angle of the steering wheels 4, 4 of the tractor 1, and when a steering angle of a predetermined value or more is detected, it is determined that the tractor is turning.

In addition, it is also possible to drive the so-called auto-lift of the work machine in conjunction with the detection of the steering angle.
b. A load sensor 53 for detecting the load on the steering wheel axle detects the load on the axle of the steering wheels 4, 4 of the tractor 1, and if a load exceeding a predetermined value is applied, it is determined that the tractor is turning. For example, a strain sensor may be attached to the traveling axle of the steering wheels 4, 4.

At this time, the load shared by the steered wheels 4, 4 may be detected using an axle load sensor. If the load shared exceeds a predetermined value, it is determined that the vehicle is turning, and the load on the steering wheel 9 is reduced.

At this time, it is desirable to change the load on the steering wheel 9 in stages according to the magnitude of the load on the steered wheels 4, 4.
c. Turning is determined by the IMU 54, such as a gyroscope. The angular velocity around the Z axis is detected, and if it exceeds a predetermined value, it is determined that the vehicle is turning.
d. When the output value of the traction sensor (draft sensor) 55 exceeds a certain level, it is determined that the vehicle is going straight, and the load on the steering wheel 9 is increased.
e. When the work equipment is lowered using the up/down switch 56 of the work equipment, it is determined that the work equipment is moving straight ahead and the load is increased.
f. When the tractor 1 in operation reaches the end of the work position (turning position) of the work route in the field, it determines that it is about to turn and reduces the load on the steering wheel 9.

To achieve this, a GNSS device 30 is installed in advance, and four points on the field's outline are acquired using this to roughly grasp the field shape. Alternatively, the field to be registered can be selected from a map app, and the shape of the target field can be roughly grasped from its latitude and longitude information. The overall width, overall length, work position, work width, etc. of the work vehicle are also registered. Based on the registered work vehicle information, work information (turning pattern, number of trees to be cultivated around, etc.) is set to generate this work route 59.

In a work vehicle that can use the straight-line assist mode function 57 when driving straight, when the straight-line assist mode is enabled, it is determined that the vehicle is going straight, and the load on the steering wheel 9 is increased.

Furthermore, when the straight-line assist function is switched from enabled to disabled, the load on the steering wheel 9 is reduced in anticipation of an upcoming turn.

Furthermore, in the above embodiment, a mode in which the load on the steering wheel 9 is changed and a mode in which the load is not changed may be prepared, allowing the operator to select between them at will. A dial system, a switch system, a memory switch system 58, or the like may be used for this selection.

An example of changing the load independently of turning will be described below (see FIG. 5).
a. The load can be changed arbitrarily.

Workers and others can change the load on the steering wheel 9 at will. It is desirable to be able to change the load on the steering wheel 9 to suit each individual, regardless of age or gender.

Specifically, the load on the steering wheel 9 can be set as desired using a steering sensitivity dial installed inside the cabin, including the ROPS. Alternatively, a switch can be used instead of a dial. Alternatively, the load can be easily changed by selecting a pre-registered load on the steering wheel 9 using a memory switch. Furthermore, even after moving to another field, work can be carried out under the same load conditions on the steering wheel 9 as in the previous field.
b) The vehicle speed is detected by the vehicle speed sensor Vs, and the load on the steering wheel 9 is changed in accordance with the vehicle speed.

The load on the steering wheel 9 may be determined in stages in advance according to the vehicle speed range and changed automatically. It may also be possible to select whether to enable or disable the mode of load change linked to vehicle speed. A selector switch may be provided for this selection, or a selector dial may be used.

Furthermore, if the vehicle speed is above a certain speed, it may be possible to prevent the load on the steering wheel 9 from being reduced, since this is dangerous.
c. The load on the steering wheel 9 is changed depending on the type of gear, for example, depending on the positions of the main transmission gear and the auxiliary transmission gear.

In the above embodiment, a case where various sensors become abnormal will be described.
a) If a detection means such as a sensor becomes abnormal, switching of the load on the steering wheel 9 is prohibited, thereby ensuring safety.
b. If a detection means such as a sensor becomes abnormal, a warning to that effect is issued.
c. If a detection means such as a sensor becomes abnormal, the details of the abnormality are displayed on the meter panel 9a.
d. Alternatively, if a detection means such as a sensor becomes abnormal, the load on the steering wheel 9 is returned to the load at the time of shipment from the factory.

The following explains how to change the load on the steering wheel 9.

1. This section describes how to change the load on the steering wheel 9 using the hydraulic power steering mechanism 40.

6, 7 and 8 are diagrams mainly showing the hydraulic circuit of the hydraulic power steering mechanism 40. The hydraulic circuit has the following structure.

Figure 6 shows the neutral state where the steering wheel 9 is not rotated. Here, 40c is an actuator that changes the variable throttles 40a and 40b in response to instructions from the control unit 20. These variable throttles 40a and 40b are components that adjust the throttle of the oil passage to the steering wheel drive hydraulic cylinder 40v as described below.

Reference numeral 40d denotes a hydraulic device called Orbitroll (registered trademark; the same applies hereinafter) that adjusts the amount of hydraulic oil sent to the steering wheel drive hydraulic cylinder 40v according to the amount of rotation of the steering wheel 9. The Orbitroll 40d is connected by a shaft 40e or the like to an oil path switching circuit 40f for switching the direction of rotation, and also plays a role in switching the oil path switching circuit 40f according to the direction of rotation of the steering wheel 9, as shown in Figure 7 when turning left, and as shown in Figure 8 when turning right.

Note that 40g is a return filter, 40h is a relief valve, and 40i is a pump.

If the control unit 20 issues a command to the actuator 40c to reduce the load on the steering wheel 9, the actuator 40c will loosen the throttles of the variable throttles 40a and 40b. Conversely, if the control unit 20 issues a command to the actuator 40c to increase the load on the steering wheel 9, the actuator 40c will further tighten the throttles of the variable throttles 40a and 40b.

In this way, the load on the steering wheel 9 can be changed.

2. Next, we will describe how to change the load on the steering wheel 9 using the electric power steering mechanism 41.

Figure 9 shows the general configuration of an electric power steering mechanism 41, including a motor control device. In Figure 9, the electric power steering mechanism 41 includes a motor control device 41a, a motor 41b, a steering wheel 9, a rotation shaft 9b of the steering wheel 9, a reduction gear 41c, etc.

An instruction signal from the control unit 20 is sent to the motor control device 41a. The motor control device 41a generates a motor drive signal based on that signal and outputs that signal to the motor 41b. To which the motor drive signal is input, the motor 41b outputs an auxiliary torque to assist in steering the steering wheel 9, and this auxiliary torque is transmitted to the rotating shaft 9b via the reduction gear 41c. As a result, the rotation of the rotating shaft 9b is assisted, thereby assisting and lightening the driver's steering effort.

As mentioned above, the configuration of the present invention may be implemented in either software or hardware.

Furthermore, the program of the invention related to the present invention is a program that causes a computer to execute all or part of the steps (or processes, operations, actions, etc.) of the control method of the invention related to the present invention described above, and is a program that operates in cooperation with a computer.

Furthermore, the recording medium of the invention related to the present invention is a recording medium on which a program is recorded that causes a computer to execute all or some of the steps (or processes, actions, functions, etc.) of the control method of the invention related to the present invention described above, and is a computer-readable recording medium from which the read program is used in cooperation with a computer.

Note that the above phrase "some steps (or processes, operations, actions, etc.)" refers to one or several steps among those multiple steps.

Furthermore, the above-mentioned "operations of steps (or processes, actions, acts, etc.)" refer to the operations of all or part of the above-mentioned steps.

Furthermore, one form of use of the inventive program related to this invention may be a form in which it is transmitted through a transmission medium such as the Internet, light, radio waves, or sound waves, read by a computer, and operates in cooperation with the computer.

In addition, recording media include ROM (Read Only Memory).

Furthermore, a computer is not limited to pure hardware such as a CPU (Central Processing Unit), but may also include firmware, an OS (Operating System), and even peripheral devices.

This invention is a work vehicle that can appropriately change the steering load depending on the situation while driving for work, and is ideal for tractors.

1 Tractor 2 Running body 3 Body frame 4 Front wheels (steering wheels)
5. Rear wheels (drive wheels)
DESCRIPTION OF REFERENCE NUMERALS 6 Hood 7 Control unit 8 Cockpit 9 Steering wheel 9a Display unit 10 Transmission case 20 Control unit 20a Determination unit 20b Numerical value setting unit 21 Steering sensor 30 GNSS device 40 Hydraulic power steering mechanism 40a, 40b Variable throttle 40c Actuator 40d Orbit roll 40e Shaft 40f Oil path switching circuit 40g Return filter 40h Relief valve 40i Pump 41 Electric power steering mechanism 41a Motor control device 41b Motor 41c Reduction gear θ Effective angle E Engine S Navigation satellite Vs Speed detection sensor

Claims (1)

A running vehicle body,
a steering wheel for changing the direction of travel of the traveling vehicle body;
a steering wheel for operating the steering wheels;
a steering sensor for detecting an operation of the steering wheel;
a control unit for changing the operation load of the steering wheel,
a hydraulic power steering mechanism is used to operate the steering wheels with the steering wheel,
The hydraulic power steering mechanism includes a hydraulic device that sends hydraulic oil to a steering wheel drive hydraulic cylinder in response to rotation of the steering wheel,
When working in the field,
When the control unit determines that the steering wheel has been turned based on the detection value of the steering sensor, it adjusts the variable throttle between the hydraulic device and the steering wheel drive hydraulic cylinder to reduce the operating load of the steering wheel compared to when the turning operation is not detected,
The steering sensor detects an angular velocity of the steering wheel operation, and the control unit determines that the steering wheel is being turned when the angular velocity exceeds a predetermined value.
When the steering wheel operation angle is equal to or greater than a predetermined effective angle, the angle of the steering wheels begins to change,
When the control unit determines that the steering wheel has been turned within a range less than the effective angle, the control unit reduces the operating load of the steering wheel compared to when the turning operation is not detected,
a control unit that, when determining that a turning operation of the steering wheel has been performed within a range equal to or greater than the effective angle, gradually reduces the operating load of the steering wheel in stages or continuously in accordance with a predetermined rule compared to when the turning operation is not detected .