WO2011083627A1

WO2011083627A1 - Steering device for vehicle

Info

Publication number: WO2011083627A1
Application number: PCT/JP2010/070107
Authority: WO
Inventors: 知彦安田; 隆之佐藤
Original assignee: 日立建機株式会社
Priority date: 2010-01-07
Filing date: 2010-11-11
Publication date: 2011-07-14

Abstract

The operational angle of the steering wheel (16) provided in a cab (6) is detected as the rotational angle (A) of the steering wheel shaft (16A) by a rotation sensor (19). When the rotational angle (A) detected by the rotation sensor (19) does not change for a predetermined time period (Cs), a controller (20) determines that the vehicle is traveling straight and stores in a memory (20A) the rotational angle (A) as a neutral angle (An). When the vehicle is traveling, the controller (20) calculates, as the actual steering angle (S) of the vehicle, the difference between the rotational angle (A) detected by the rotation sensor (19) and the neutral angle (An) stored in the memory (20A), and the controller (20) outputs the actual steering angle (S) through a motor control device (13) to motors (12) on the rear wheel (8) side. The configuration enables the actual steering angle to be stably obtained when the the vehicle is steered.

Description

Vehicle steering system

The present invention relates to a vehicle steering apparatus that is mounted on a transport vehicle such as a dump truck and is preferably used to steer the vehicle.

Generally, a large transport vehicle called a dump truck has a vessel (loading platform) that can be raised and lowered on a frame of a vehicle body. This dump truck travels in a state where a large amount of transport objects made of crushed stone or earth and sand are loaded on a vessel (Patent Document 1).

This type of prior art transport vehicle includes a self-propelled vehicle body, a cargo bed provided on the vehicle body so as to be capable of tilting (raising and lowering), and a transport object to be loaded thereon, and the vehicle body located on the front side of the cargo bed. And a cab that defines a cab inside. In the cab of the transport vehicle, a steering handle is provided for a driver to grip and steer the traveling direction of the vehicle.

In addition, a conventional transport vehicle is equipped with a steering device called a power steering device (power steering) configured to steer the vehicle using hydraulic pressure so that the driver can lighten the steering wheel operation. Has been. Such a steering apparatus includes a steering handle, a steering valve that controls supply and discharge of pressure oil in accordance with the operation of the steering handle, and a steering that steers the vehicle with the pressure oil that is supplied and discharged through the steering valve. It is comprised including a cylinder (patent document 2).

By the way, in the case of the steering device equipped in the transport vehicle described above, the steering wheel (for example, the front wheel) whose direction changes based on the operation angle of the steering wheel (for example, the turning angle of the steering wheel with respect to the neutral state) and the operation of the steering wheel. ) Is not necessarily determined uniformly. That is, the correlation between the operation angle of the steering wheel and the steering angle of the steered wheels is sequentially changed when an oil leak occurs in the steering valve.

On the other hand, in order to correct the correspondence between the steering wheel operation angle and the steering wheel steering angle, for example, a configuration in which a steering angle sensor such as a potentiometer is provided on a king pin that supports a front wheel (steering wheel) is known. (Patent Document 3).

There is also known a configuration in which the rotational speeds of the front wheels and the rear wheels of a vehicle that performs four-wheel drive are independently controlled based on a detection signal of a steering angle sensor provided in the lower part of the vehicle (Patent Document). 4).

JP 2009-262750 A JP-A-5-155344 Japanese Patent Laid-Open No. 10-316000 JP-A-6-156101

However, in the prior arts disclosed in Patent Documents 3 and 4 described above, since a high-resolution steering angle sensor made of precision parts is attached to the lower part of the vehicle, it is necessary to protect the steering angle sensor from flying stones, mud, etc. during traveling. There is. For this reason, in these prior arts, there is a problem that the structure of the mounting portion of the steering angle sensor becomes complicated.

On the other hand, it is also conceivable to obtain the steering angle of the steered wheel from the amount of expansion / contraction of the steering cylinder. However, in this case as well, a sensor for detecting the amount of expansion / contraction of the steering cylinder needs to be provided with a high-resolution sensor such as a displacement sensor in the lower part of the vehicle, which increases costs and complicates the structure of the sensor mounting portion. There is a fear.

In addition, when a high-resolution sensor such as that described above breaks down, if the correspondence between the steering wheel operation angle and the steering wheel steering angle shifts with oil leakage, the actual steering on the steering wheel side There is a problem that it is difficult to detect an angle, that is, an actual steering angle.

The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to stably obtain an actual steering angle (actual steering angle of a steered wheel) of a vehicle with a simple configuration. An object of the present invention is to provide a vehicle steering apparatus.

(1). In order to solve the above-described problems, the present invention provides a steering handle that is operated by a driver, a steering valve that controls supply and discharge of pressure oil according to the operation of the steering handle, and supply and discharge through the steering valve. The present invention is applied to a vehicle steering apparatus including a steering cylinder that steers the vehicle with the pressurized oil.

The feature of the configuration adopted by the present invention is that an operation angle detection unit that detects an operation angle of the steering handle, a straight travel determination unit that determines whether or not the vehicle is traveling straight when the vehicle is traveling, and the straight travel When the determination means determines that the vehicle is traveling straight, a neutral angle storage means for storing an operation angle by the operation angle detection means as a neutral angle during vehicle travel, and an operation detected by the operation angle detection means An actual steering angle calculating means for calculating the actual steering angle of the vehicle based on the angle and the neutral angle stored by the neutral angle storage means.

According to this configuration, it is possible to determine whether or not the vehicle is traveling straight when the vehicle is traveling by the straight traveling determination unit. When the vehicle is traveling straight, the operation angle output from the operation angle detection unit can be stored as a neutral angle during vehicle travel by the neutral angle storage unit so as to be updatable. On the other hand, the actual steering angle calculation means is based on the operation angle detected by the operation angle detection means and the neutral angle stored by the neutral angle storage means. Steering angle) can be obtained stably by calculation.

That is, according to the present invention, the operation angle output from the operation angle detection means when the vehicle is traveling straight is stored in an updatable manner as the neutral angle when the vehicle is traveling, so that the actual steering of the vehicle is performed based on the updated neutral angle. In this configuration, the angle is obtained by calculation. As a result, the steering angle at which the steering wheel (for example, the front wheel) of the vehicle is actually steered can be made to coincide with the actual steering angle obtained by calculation, and the steering control of the vehicle can be stabilized using this actual steering angle. Can be done. Further, according to the present invention, it is not necessary to provide a high-resolution sensor on the lower side of the vehicle for directly detecting the steering angle on the front wheel side which is the steering wheel of the vehicle, so that the actual steering angle of the vehicle is obtained. In addition to simplifying the configuration and making effective use of the space, it is possible to reduce costs by eliminating the need for a high-resolution sensor.

(2). According to the present invention, the actual steering angle calculation means calculates an angle difference between the operation angle detected by the operation angle detection means and the neutral angle stored by the neutral angle storage means, and based on this angle difference, the vehicle The actual steering angle is obtained.

According to this configuration, the steering angle calculation means obtains the actual steering angle of the vehicle from the angle difference between the operation angle by the operation angle detection means and the neutral angle by the neutral angle storage means. The actual steering angle can be obtained stably.

(3). Further, according to the present invention, the straight traveling determination unit determines whether the vehicle is traveling straight by monitoring whether or not the operation angle detected by the operation angle detection unit changes over a predetermined time. The neutral angle storage means stores the operation angle detected by the operation angle detection means over the predetermined time as the neutral angle.

According to this configuration, the straight travel determination means determines straight travel of the vehicle based on the change in the operation angle detected by the operation angle detection means, so that further simplification and cost reduction can be achieved. That is, when the vehicle is traveling straight, the vehicle driver maintains a state in which a constant operation angle is maintained without operating the steering wheel. Therefore, the straight traveling determination means determines whether or not a predetermined time has passed without the steering handle being operated, in other words, the operation angle detected by the operation angle detection means is not changed substantially. Monitor whether time has passed. Thereby, the straight-ahead determination unit can stably determine whether or not the vehicle is traveling straight ahead.

(4). The present invention includes a yaw rate detection means for detecting a yaw rate (rotational angular velocity about the vertical axis of the center of gravity of the vehicle) during travel of the vehicle, and the straight travel determination means is based on a detection signal detected by the yaw rate detection means. It is configured to determine whether or not the vehicle is traveling straight.

According to this configuration, since it is determined whether or not the vehicle is traveling straight on the basis of the yaw rate detected by the yaw rate detecting means, the determination whether or not the vehicle is traveling straight is accurately and stably determined based on the yaw rate. Can be done. In particular, since the yaw rate detecting means can be provided in the driver's cabin of the vehicle, it is not exposed to stepping stones, earth and sand, muddy water, dust, etc. unlike the lower part of the vehicle. For this reason, it is not necessary to provide a special protection means for the yaw rate detection means, and it can be configured with a simple structure and at a low cost as compared with the steering angle sensor of the prior art.

(5). The present invention includes a rectilinear detection switch for detecting whether or not the vehicle is traveling straight, and the rectilinear determination means determines whether or not the vehicle is traveling straight based on a detection signal from the rectilinear detection switch. It is configured.

With this configuration, it is possible to determine whether or not the vehicle is traveling straight by a detection signal (for example, an ON-OFF signal) from the straight travel detection switch. In particular, since the straight detection switch can be configured as a simple ON-OFF switch, its durability and life can be improved even when it is provided at the bottom of the vehicle, and no special protective means is required. Can do.

(6). According to the present invention, a self-propelled vehicle body having a front wheel and a rear wheel, a loading platform provided on the vehicle body so as to be tiltable with the rear side as a fulcrum and on which a transportation object is loaded, and on the front side of the loading platform A cab located in the vehicle body and defining a driver's cab inside, and a hoist cylinder provided between the cargo bed and the vehicle body and tilting the cargo bed backward when discharging the object to be transported from the cargo bed The steering wheel is provided in the cab, the steering cylinder is provided in the front wheel, and the steering valve is provided in the vehicle body.

1 is a front view showing a dump truck to which a steering device according to a first embodiment of the present invention is applied. It is a block diagram which shows the steering device of a dump truck including a motor for driving, a rear wheel, etc. It is a flowchart which shows the straight-ahead determination process by a controller, a neutral angle memory | storage process, an actual steering angle calculation process, etc. FIG. 3 is a configuration diagram similar to FIG. 2 illustrating a steering device according to a second embodiment of the present invention including a traveling motor, a rear wheel, and the like. FIG. 4 is a flowchart similar to FIG. 3 showing a straight-ahead determination process, a neutral angle storage process, an actual steering angle calculation process, and the like by a controller. It is sectional drawing similar to FIG. 2 which shows the steering device by the 3rd Embodiment of this invention including a motor for driving, a rear wheel, etc. It is an attachment state figure which shows the straight detection switch, steering cylinder, etc. in FIG. FIG. 4 is a flowchart similar to FIG. 3 showing a straight-ahead determination process, a neutral angle storage process, an actual steering angle calculation process, and the like by a controller.

Hereinafter, the embodiment of the vehicle steering apparatus according to the present invention will be described in detail with reference to the accompanying drawings, taking as an example a case where the embodiment is applied to a dump truck that transports crushed stones mined in a mine or the like.

First, FIGS. 1 to 3 show a first embodiment of a vehicle steering system according to the present invention. In the figure, reference numeral 1 denotes a dump truck as a vehicle (large transport vehicle). The dump truck 1 includes a vehicle body 2 having a sturdy frame structure as shown in FIG. 1, and a rear side on the vehicle body 2 as a fulcrum. It is roughly constituted by a vessel 3 as a loading platform mounted so as to be capable of tilting (raising and falling).

The vessel 3 is formed as a large container having a total length of 10 to 13 meters in order to load a large amount of a heavy transport object (hereinafter referred to as a crushed stone 4) made of crushed stone, for example. It is connected to the rear end side via a connecting pin 5 so as to be tiltable. Further, on the upper front side of the vessel 3, a flange 3 </ b> A that covers a cab 6 described later from above is integrally provided.

That is, the bottom side of the vessel 3 is rotatably supported by the connecting pin 5 on the rear side of the vehicle body 2. The front side (the flange 3A side) of the vessel 3 is rotated (lifted / lowered) upward and downward with the connecting pin 5 as a fulcrum by extending or contracting a hoist cylinder 9 described later.

6 is a cab located on the front side of the vessel 3 and provided at the front part of the vehicle body 2, and the cab 6 forms a driver's cab where a driver (operator) of the dump truck 1 gets on and off. In the cab 6, a driver's seat, a start switch, an accelerator pedal, a brake pedal (all not shown), a steering handle 16 described later, and the like are provided.

The collar 3A of the vessel 3 covers the cab 6 almost completely from the upper side, thereby protecting the cab 6 from a stepping stone such as a rock, and driving the cab 6 when the vehicle (dump truck 1) falls. It has a function to protect the person.

Reference numeral 7 denotes left and right front wheels that are rotatably provided on the front side of the vehicle body 2. The front wheels 7 have a tire diameter (outside diameter dimension) of, for example, 2 to 4 meters, as in the case of the rear wheel 8 described later. ). These left and right front wheels 7 are steered as the steering cylinder 18 extends and contracts when the driver of the dump truck 1 operates a steering handle 16 described later.

Reference numeral 8 denotes left and right rear wheels rotatably provided on the rear side of the vehicle body 2. The rear wheels 8 constitute drive wheels of the dump truck 1 and are driven to rotate by a travel motor 12 described later. . The dump truck 1 travels on the road by driving the left and right rear wheels 8 to rotate.

Reference numeral 9 denotes a pair of left and right hoist cylinders (only one is shown in FIG. 1) provided between the vehicle body 2 and the vessel 3 so as to be able to expand and contract. The hoist cylinder 9 is expanded and contracted upward and downward. By doing so, the vessel 3 is tilted (raised) with the connecting pin 5 as a fulcrum.

10 is a hydraulic oil tank that is located below the vessel 3 and is attached to the side surface of the vehicle body 2. The hydraulic oil tank 10 contains hydraulic oil (oil) therein. Then, the hydraulic oil stored in the hydraulic oil tank 10 is supplied and discharged to the hoist cylinder 9, a steering cylinder 18, which will be described later, and the like by the hydraulic pump 15 which will be described later.

11 is an engine provided in the vehicle body 2 located below the cab 6, and the engine 11 is composed of, for example, a large diesel engine. The engine 11 drives a main generator (not shown) to generate three-phase AC power (for example, about 1500 kW), and rotationally drives a hydraulic pump 15 and the like which will be described later. It also has a function of supplying and discharging pressure oil to a steering cylinder 18 described later.

12 indicates a pair of traveling motors provided on the vehicle body 2 via an accelerator housing (not shown). Here, each traveling motor 12 is rotationally driven by the electric power supplied from the main generator via the motor control device 13, and is constituted by a large electric motor.

Further, each traveling motor 12 is rotationally driven independently by a motor control device 13, and a control signal from a controller 20 described later is input to the motor control device 13. Based on this control signal, the motor control device 13 makes the rotation speeds of the left and right rear wheels 8 the same when the vehicle goes straight, or changes the rotation speeds of the left and right rear wheels 8 according to the turning direction when turning. It is configured to perform control such as making them different.

Next, the configuration of the steering device 14 that is a main part of the first embodiment will be described.

This steering device 14 is a power steering (power steering device) in which the direction of the front wheel 7 which is a steered wheel can be changed with a light operating force using oil pressure in accordance with the operation of the steering handle 16 by the driver. is there. Here, the steering device 14 includes a hydraulic pump 15, a steering handle 16, a steering valve 17, a steering cylinder 18, a rotation sensor 19, a controller 20, and the like which will be described later.

15 is a hydraulic pump provided in the vicinity of the engine 11, and the hydraulic pump 15 is rotationally driven by the engine 11 to supply pressure oil to a steering cylinder 18 described later.

Reference numeral 16 denotes a steering handle (steering wheel) which is provided in the cab 6 and is steered by the driver. The steering handle 16 is gripped by the driver and rotates the handle shaft 16A to the left and right, so that the vehicle The steering operation is performed.

17 is a steering valve for controlling the supply and discharge of pressure oil to a steering cylinder 18 which will be described later in accordance with the operation of the steering handle 16. The steering valve 17 includes a valve housing 17A and a spool valve (not shown) provided in the valve housing 17A.

Here, the spool valve in the valve housing 17 is connected to the handle shaft 16A, and is switched according to the turning operation of the steering handle 16. At this time, the flow rate of the pressure oil from the hydraulic pump 15 and the supply direction of the pressure oil are controlled according to the switching operation of the steering valve 17.

18 is a pair of steering cylinders for steering the vehicle by the pressure oil supplied and discharged through the steering valve 17. Each steering cylinder 18 is provided on the front wheel 7 side, and applies a steering force by oil pressure to the left and right front wheels 7.

That is, as shown in FIG. 2, the left and right steering cylinders 18 extend and contract when pressure oil from the hydraulic pump 15 is supplied via the steering valve 17 and the hydraulic passage 21. The left and right front wheels 7 are moved in the steering direction by the expansion and contraction of the respective steering cylinders 18.

19 is a rotation sensor as an operation angle detection means for detecting the operation angle A of the steering handle 16, and the rotation sensor 19 is constituted by, for example, an electromagnetic pickup type or an optical rotation detector. The rotation sensor 19 detects an operation angle A of the operation handle 16 as a rotation angle A of the handle shaft 16A, and outputs a rotation detection signal to a controller 20 described later.

Reference numeral 20 denotes a controller as a control device constituted by a microcomputer or the like, and the controller includes a straight traveling determination means, a neutral angle storage means, an actual steering angle calculation means, and the like which are constituent features of the present invention. Here, the controller 20 has an input side connected to the rotation sensor 19 and an output side connected to the motor control device 13.

On the other hand, the controller 20 has a memory 20A as a neutral angle storage means composed of ROM, RAM (including nonvolatile memory) and the like. The memory 20A of the controller 20 stores a neutral angle An, a threshold value Da, a predetermined time Cs, a memory value Aom, a memory value Anm, and the like shown in FIG. Further, the memory 20A of the controller 20 stores a program or the like for performing processing shown in FIG. 3 to be described later, that is, straight traveling determination processing, neutral angle storage processing, and actual steering angle calculation processing.

Here, the straight-ahead determination process is a process for determining whether or not the vehicle is traveling straight when the vehicle (dump truck 1) is traveling. That is, whether or not the operation angle (rotation angle of the handle shaft 16A) A detected by the rotation sensor 19 changes over a predetermined time (for example, between 2 to 8 seconds) is determined more accurately. It is determined whether or not the vehicle is traveling straight by monitoring whether or not the amount of change in angle A is less than a threshold value Da (eg, Da = 0.5 to 1.5 degrees) that is negligible when traveling straight. It is.

Here, when the operation angle A by the rotation sensor 19 does not change over a predetermined time (for example, when the change amount of the operation angle A is smaller than the threshold value Da in 2 to 8 seconds), the vehicle travels straight. Is determined. On the other hand, if the operation angle A changes beyond the threshold value Da during the predetermined time, it is determined that the vehicle is not traveling straight.

The neutral angle storage process is a process of storing the operation angle A detected by the rotation sensor 19 as the vehicle neutral angle An in the memory 20A in an updatable manner when it is determined that the vehicle is traveling straight by the straight traveling determination process. is there. That is, when the front wheel 7 serving as the steering wheel is accurately mounted in advance and the steering angle on the front wheel side and the operation angle A of the rotation sensor 19 coincide with each other, the operation angle A when the vehicle goes straight becomes zero degrees, and the neutral angle An is also stored in the memory 20A as zero degree.

Further, the actual steering angle calculation process is to calculate the actual steering angle S of the vehicle based on the operation angle A by the rotation sensor 19 and the neutral angle An stored in the memory 20A. That is, the actual steering angle S is calculated by calculating the angle difference (A−An) between the operation angle A by the rotation sensor 19 and the neutral angle An stored in the memory 20A according to the following equation (2). The actual steering angle S of the vehicle is obtained from the difference (A−An).

That is, the controller 20 performs the straight traveling determination process, the neutral angle storage process, and the actual steering angle calculation process as described above, so that the operation angle A of the steering handle 16 detected by the rotation sensor 19 and the vehicle travel straight. Based on the neutral angle An corresponding to the operation angle A stored in the memory 20A when it is determined that the actual steering angle S of the vehicle is calculated according to the equation (2).

Further, the controller 20 calculates the target rotational speeds of the left and right traveling motors 12 based on the actual steering angle S thus calculated, and the rotational speeds of the respective traveling motors 12 reach the target rotational speeds. Thus, a control signal for controlling each of the traveling motors 12 is output to the motor control device 13. As a result, based on the control signal from the controller 20, the motor control device 13 makes the left and right rear wheels 8 have the same rotational speed when the vehicle goes straight, or the left and right rear according to the turning direction when turning. Control such as varying the rotation speed of the wheel 8 is performed.

The dump truck 1 according to the first embodiment has the above-described configuration, and the operation thereof will be described next.

First, in a quarry such as a mine, a crushed stone 4 to be transported is loaded on the vessel 3 using a large hydraulic excavator (not shown). At this time, the vessel 3 is disposed at the transport position shown in FIG. Then, the dump truck 1 transports the crushed stone 4 toward a predetermined unloading place with a large amount of crushed stone 4 loaded on the vessel 3.

On the other hand, in the unloading place, the driver in the cab 6 manually operates an operation lever (not shown) to extend the hoist cylinder 9 and tilt the vessel 3 obliquely backward. Thereby, the crushed stone 4 in the vessel 3 is discharged from the vessel 3 so as to slide down.

Next, when the discharge of the crushed stone 4 is completed, the driver manually operates the operation lever to reduce the hoist cylinder 9. Thereby, the vessel 3 is rotated to the transport position shown in FIG. 1 and is seated on the vehicle body 2. The dump truck 1 is prepared for the next transport operation in this state.

On the other hand, when the dump truck 1 travels on the road, when the driver in the cab 6 rotates the steering handle 16 leftward or rightward, the spool valve of the steering valve 17 is switched. In response to the switching of the spool valve, pressure oil is supplied toward the left and right steering cylinders 18. As a result, the steering cylinder 18 extends and contracts, and the left and right front wheels 7 can be moved in the steering direction.

Further, the left and right traveling motors 12 that rotationally drive the left and right rear wheels 8 when traveling on the road are independently controlled according to the actual steering angle S signal output from the controller 20. . In this case, if the operation angle A of the steering handle 16 detected by the rotation sensor 19 is used as it is as the vehicle steering angle (wheel steering angle), the required control cannot be stably performed. For this reason, at the time of steering operation of the vehicle, the left and right rear wheels 8 cannot be rotationally driven at different rotational speeds at a ratio corresponding to the steering angle on the front wheel 7 side, thereby improving the steering performance of the vehicle. It becomes difficult.

Therefore, in the first embodiment, in order to solve such a problem, the actual steering of the vehicle is performed by executing the processing shown in FIG. 3 (straight advance determination processing, neutral angle storage processing, actual steering angle calculation processing). The angle S is obtained by calculation. Further, the signal of the actual steering angle S is output from the controller 20 to the motor control device 13 as a control signal for rotationally driving the left and right traveling motors 12.

That is, when the processing operation shown in FIG. 3 is started by starting the engine 11, first, in step 1, initial setting is performed. In this initial setting, the counter C for measuring time is set to 0, the previous operation angle (rotation angle) Ao, which is the previous operation angle A, is read as the memory value Aom, and the neutral angle An obtained by the previous processing is stored as the memory value Anm. Is read out. Here, the memory values Aom and Anm correspond to the previous operation angle Ao and neutral angle An stored at the time in the memory 20A in the process of the previous program cycle.

In step 2, the operation angle (rotation angle of the handle shaft 16A) A of the steering handle 16 is read from the rotation sensor 19. In step 3, whether or not the absolute value of the difference between the operation angle A and the previous operation angle Ao is less than a threshold value Da (for example, Da = 0.5 to 1.5 degrees), as shown in the following equation (1). Determine whether.

If "YES" is determined in the step 3, the process proceeds to a step 4, the current counter C is incremented by 1 (C = C + 1), and the process proceeds to the step 5. In step 5, the current counter C determines whether or not the operation angle A has changed over a predetermined time Cs (for example, Cs = 2 to 8 seconds).

If “YES” is determined in the step 5, it is a case where the operation angle A of the steering wheel 16 has not substantially changed over the predetermined time Cs. In this case, it is determined that the vehicle is traveling straight ahead. Can do.

Therefore, at this time, the routine proceeds to step 6 where the immediately previous operation angle Ao, which is the operation angle A at this time, is stored in the memory 20A in an updatable manner as the neutral angle An when the vehicle goes straight. In step 6, the operation angle A read in step 2 is updated as the previous operation angle Ao, and the counter C is reset to zero.

Next, in step 7, the difference (A-An) between the operation angle A read in step 2 and the neutral angle An (A-An) is obtained as the actual steering angle S as shown in the following equation (2).

Next, the process proceeds to step 8 to determine whether or not the engine 11 is stopped (powered off). If “NO” is determined in the step 8, the process returns to the step 2. On the other hand, if "YES" is determined in the step 8, the process proceeds to a step 9 and an end process is performed. In this end processing, the previous operation angle Ao and the neutral angle An at that time are stored in the memory 20A as memory values Aom and Anm, respectively.

On the other hand, when “NO” is determined in Step 3, the difference between the operation angle A and the previous operation angle Ao is equal to or greater than the threshold value Da, and the steering handle 16 is being steered. In this case, since it can be determined that the vehicle is turning and is not traveling straight, the process proceeds to step 10 where the previous operation angle Ao is updated to the operation angle A read in step 2 and the counter C is reset to zero. Then, the process proceeds to Step 7.

That is, since it is determined in step 3 that the operation angle A has changed (the vehicle is not in a straight traveling state), the counter addition, the neutral angle An update, and the previous operation angle Ao are updated by the processing in steps 4 to 6 described above. Without performing this, the previous operation angle Ao is updated in Step 10 and the counter C is reset to zero, and then the operation shifts to the calculation of the actual steering angle S in Step 7.

If “NO” is determined in Step 5, the process proceeds to Step 7 without going through Step 6. That is, since it is determined in step 5 that the predetermined time Cs has not elapsed, the actual steering angle in step 7 is not performed without updating the neutral angle An in step 6, updating the previous operation angle Ao, and resetting the counter C to zero. Move on to the operation of S.

Thus, according to the first embodiment, the controller 20 executes the process shown in FIG. 3 when the vehicle is in operation. That is, the controller 20 stores the operation angle of the steering handle 16 (rotation angle of the handle shaft 16A) A detected by the rotation sensor 19 and the memory 20A when it is determined that the vehicle is traveling straight when the vehicle is operating. Based on the neutral angle An corresponding to the operated angle A, the actual steering angle S of the vehicle is calculated. Accordingly, the actual steering angle S can be stably obtained as the actual steering angle on the front wheel 7 side.

That is, by storing the operation angle A output from the rotation sensor 19 when the vehicle is traveling straight as the neutral angle An when the vehicle is traveling, the actual steering angle S of the vehicle based on the updated neutral angle An. Is obtained by calculation. Therefore, the steering angle at which the left and right front wheels 7 are actually steered can be made to coincide with the actual steering angle S obtained by calculation, and the stability of vehicle control performed using the actual steering angle S is improved. it can. In addition, since it is not necessary to provide a high-resolution sensor for directly detecting the steering angle on the front wheel 7 side on the lower side of the vehicle, the configuration for obtaining the actual steering angle S of the vehicle can be simplified, and the space can be used effectively. Can be achieved. Furthermore, the cost can be reduced because a high-resolution sensor is not required.

On the other hand, since the controller 20 determines straight traveling of the vehicle based on the change of the operation angle A detected by the rotation sensor 19, further simplification and cost reduction can be achieved. That is, the driver of the vehicle maintains a state in which a constant operating angle is maintained without operating the steering handle 16 when the vehicle is traveling straight ahead. Therefore, the controller 20 executes a straight-ahead determination process (the processes of steps 3 to 5 in FIG. 3), and whether or not a predetermined time has passed without the steering handle 16 being operated, that is, a rotation sensor. It is monitored whether or not the predetermined time Cs has elapsed without substantially changing the operating angle A detected at 19. As a result, it can be determined stably whether the vehicle is traveling straight ahead.

Further, the controller 20 executes a steering angle calculation process (the process of step 7 in FIG. 3), and the angle difference (A−An) between the operation angle A by the rotation sensor 19 and the neutral angle An stored in the memory 20. Thus, the actual steering angle S of the vehicle can be obtained, so that the actual steering angle of the vehicle can be obtained stably without performing complicated calculations.

Next, FIGS. 4 to 5 show a second embodiment of the present invention. The feature of this embodiment is that it is configured to determine whether or not the vehicle is traveling straight based on the yaw rate (rotational angular velocity around the vertical axis of the center of gravity of the vehicle) when the vehicle is traveling. In the second embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

In the figure, reference numeral 31 denotes a yaw rate sensor provided on the vehicle body, and the yaw rate sensor 31 is housed and provided in a vehicle including a driver's cab of the vehicle, for example. The yaw rate sensor 31 detects a yaw rate Y when the vehicle is traveling, and outputs a yaw rate detection signal representing the yaw rate Y to the controller 20. Further, the controller 20 to which the yaw rate detection signal is input executes the process shown in FIG. 5 based on the rotation detection signal (signal corresponding to the operation angle A) of the rotation sensor 19 in addition to the yaw rate detection signal. Thus, the actual steering angle S of the vehicle is calculated. Hereinafter, the process shown in FIG. 5 will be described.

When the processing operation shown in FIG. 5 is started by starting the engine 11, first, in step 11, initial setting is performed. In this initial setting, the neutral angle An obtained by the previous process is read as the memory value Anm. Here, the memory value Anm corresponds to the neutral angle An at that time stored in the memory 20A by the processing in the previous program cycle.

Next, in step 12, the operation angle A of the steering handle 16 is read from the rotation sensor 19, and the yaw rate Y of the vehicle is read from the yaw rate sensor 31, and the process proceeds to step 13. In this step 13, it is determined whether or not the yaw rate Y is less than a threshold value Dy (a value in which the vehicle is considered not to go straight if the yaw rate Y is greater than this).

If "YES" is determined in the step 13, it can be determined that the vehicle is traveling straight, so the process proceeds to a step 14, and the operation angle A read in the step 12 is stored as a neutral angle An when the vehicle is traveling straight. 20A is stored in an updatable manner, and the process proceeds to Step 15.

In step 15, as in step 7 described in the first embodiment, the difference (A−An) between the operation angle A read in step 12 and the neutral angle An is set as the actual steering angle S. And go to step 16.

In step 16, it is determined whether or not the engine 11 has been stopped (powered off) as in step 8 of the first embodiment described above. If “NO” is determined in the step 16, the process returns to the step 12. On the other hand, if "YES" is determined in the step 16, the process proceeds to a step 17 and an end process is performed. In this termination process, the neutral angle An at that time is stored in the memory 20A as the memory value Anm.

On the other hand, when it is determined “NO” in step 13, it can be determined that the vehicle is not traveling straight (for example, turning), so the process proceeds to step 15 without going through step 14. That is, since it is determined that the vehicle is not traveling straight, the neutral angle An is not updated, and the process proceeds to the calculation of the actual steering angle S in step 15.

According to the second embodiment, the controller 20 determines whether or not the vehicle is traveling straight on the basis of the yaw rate Y detected by the yaw rate sensor 31, and further determines that the vehicle is traveling straight. The actual steering angle S of the vehicle is calculated based on the neutral angle An corresponding to the operation angle A. Therefore, also in the second embodiment, the actual steering angle S can be stably obtained as the actual steering angle on the front wheel 7 side, and the same effect as the first embodiment described above can be obtained. .

In the second embodiment, whether or not the vehicle is traveling straight can be determined accurately and stably based on the yaw rate Y detected by the yaw rate sensor 31. In particular, the yaw rate sensor 31 may be provided inside the vehicle including the driver's cab of the vehicle, and does not need to be provided at a place exposed to stepping stones, earth and sand, muddy water, dust, or the like as in the lower part of the vehicle. For this reason, it is not necessary to provide a special protection means for the yaw rate sensor 31, and it can be configured with a simple structure and at a low cost as compared with the steering angle sensor of the prior art.

Next, FIGS. 6 to 8 show a third embodiment of the present invention. The feature of this embodiment is that it is configured to determine whether or not the vehicle is traveling straight on the basis of the detection signal of the straight traveling detection switch. Note that in the third embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

In the figure, 41 is a protrusion provided on a knuckle arm 42 that supports the front wheel 7, and the protrusion 41 protrudes on the opposite side of the rotation center of the front wheel 7 across the king pin 43 of the knuckle arm 42. It is formed as follows.

Reference numeral 44 denotes a rectilinear detection switch for detecting whether or not the vehicle is traveling straight. The rectilinear detection switch 44 is fixed to the vehicle body 2 in a state of being opposed to the protrusion 41 of the knuckle arm 42 through a minute gap. . Here, the rectilinear detection switch 44 is configured by using, for example, a non-contact type electromagnetic pickup, a Hall element, and the like, and the vehicle changes due to a magnetic field change when approaching and separating from the protrusion 41 of the steel knuckle arm 42. Is detected as an ON-OFF signal. Accordingly, the straight travel detection switch 44 outputs a straight travel detection signal K consisting of an ON-OFF signal to the controller 20.

That is, the straight detection switch 44 outputs an ON signal when the vehicle is traveling straight (the projection 41 is close), and when the vehicle is turning (the projection 41 is separated). Outputs an OFF signal. Then, the controller 20 to which the straight travel detection signal K is input, based on the rotation detection signal (signal corresponding to the operation angle A) of the rotation sensor 19 in addition to the straight travel detection signal K, the processing shown in FIG. Is executed to calculate the actual steering angle S of the vehicle. Hereinafter, the process shown in FIG. 8 will be described.

When the processing operation shown in FIG. 8 is started by starting the engine 11, initialization is performed in step 21. In this initial setting, similarly to step 11 of the second embodiment described above, a process of reading the neutral angle An by the previous process as the memory value Anm is performed.

In step 22, the operation angle A of the steering handle 16 is read from the rotation sensor 19, and the straight-ahead detection signal K is read from the straight-ahead detection switch 44, and the process proceeds to step 23. In step 23, it is determined whether or not the straight detection signal K is an ON signal.

If "YES" is determined in the step 23, it can be determined that the vehicle is traveling straight, so the process proceeds to the step 24, and the operation angle A read in the step 22 is set as the neutral angle An when the vehicle is traveling straight in the memory 20A. Is stored in an updatable manner, and the process proceeds to Step 25.

In step 25, as in step 7 of the first embodiment, the difference (A−An) between the operation angle A read in step 22 and the neutral angle An is obtained as the actual steering angle S. Move on.

In step 26, as in step 8 of the first embodiment, it is determined whether or not the engine 11 has been stopped (powered off). If “NO” is determined in the step 26, the process returns to the step 22, and if “YES” is determined, the process proceeds to a step 27 and an end process is performed. In this termination process, the neutral angle An at that time is stored in the memory 20A as the memory value Anm.

On the other hand, if “NO” is determined in Step 23, it can be determined that the vehicle is not traveling straight (for example, turning), and therefore, the process proceeds to Step 25 without going through Step 24. That is, since it is determined that the vehicle is not traveling straight, the neutral angle An is not updated, and the process proceeds to the calculation of the actual steering angle S in step 25.

The dump truck 1 according to the third embodiment determines whether or not the vehicle is traveling straight based on the straight traveling detection signal K detected by the straight traveling detection switch 44, and further determines that the vehicle is traveling straight. The actual steering angle S of the vehicle is calculated based on the neutral angle An corresponding to the operation angle A. Therefore, also in the third embodiment, the actual steering angle S can be stably obtained as the actual steering angle on the front wheel 7 side, and the same operational effects as those of the first embodiment described above can be obtained. it can.

In the third embodiment, whether the vehicle is traveling straight can be determined by an ON-OFF signal from the straight traveling detection switch 44. In particular, the straight-ahead detection switch 44 can be configured as a simple ON-OFF switch, so even when it is provided at the bottom of the vehicle, its durability and life can be increased, and no special protection means is required. Can do.

In the first embodiment, the processing of steps 3 to 5 shown in FIG. 3 is performed, in the second embodiment, the processing of step 13 shown in FIG. 5 is performed, and in the third embodiment, processing is performed as shown in FIG. The process of step 23 shows a specific example of the straight-ahead determination means which is a constituent requirement of the present invention.

Further, in the first embodiment, the process of step 6 shown in FIG. 3 is performed, in the second embodiment, the process of step 14 shown in FIG. 5 is performed, and in the third embodiment, the process of step 24 shown in FIG. The processing shows a specific example of the neutral angle storage means which is a constituent requirement of the present invention.

In the first embodiment, the process of step 7 shown in FIG. 3 is performed, in the second embodiment, the process of step 15 shown in FIG. 5 is performed, and in the third embodiment, the process of step 25 shown in FIG. The processing shows a specific example of actual steering angle calculation means which is a constituent requirement of the present invention.

On the other hand, in each of the above-described embodiments, the case where a hydraulic pump is used as a hydraulic source has been described as an example. However, the present invention is not limited to this, and for example, an accumulator may be used. In this case, the hydraulic pump can be stopped when the vehicle is traveling.

Further, in each of the above-described embodiments, the dump truck, which is a large transport vehicle, has been described as an example. However, the present invention is not limited to this, and for example, other than a small transport vehicle, a passenger vehicle, and the like. It is good also as a structure mounted in this vehicle.

1 Dump truck (vehicle)
14 Steering device 16 Steering handle 17 Steering valve 18 Steering cylinder 19 Rotation sensor (operation angle detecting means)
20 controller (straight-ahead determination means, neutral angle storage means, actual steering angle calculation means)
20A memory (neutral angle storage means)
31 Yaw rate sensor 44 Straight line detection switch

Claims

Steering handle that the driver steers, a steering valve that controls supply and discharge of pressure oil according to the operation of the steering handle, and a steering cylinder that steers the vehicle by the pressure oil supplied and discharged through the steering valve In a vehicle steering apparatus comprising:
An operation angle detection means for detecting an operation angle of the steering wheel;
Straight travel determination means for determining whether or not the vehicle is traveling straight when the vehicle is traveling;
A neutral angle storage means for storing the operation angle by the operation angle detection means as a neutral angle during vehicle travel when the straight movement determination means determines that the vehicle is moving straight;
An actual steering angle calculation unit that calculates an actual steering angle of the vehicle based on the operation angle detected by the operation angle detection unit and the neutral angle stored by the neutral angle storage unit is provided. A vehicle steering system.
The actual steering angle calculation means calculates an angle difference between the operation angle detected by the operation angle detection means and the neutral angle stored by the neutral angle storage means, and the actual steering angle of the vehicle is calculated based on the angle difference. The vehicle steering device according to claim 1, wherein the vehicle steering device is configured to be obtained.
The straight-ahead determination unit is configured to determine whether the vehicle is traveling straight by monitoring whether or not the operation angle detected by the operation angle detection unit changes over a predetermined time, and stores the neutral angle storage The vehicle steering apparatus according to claim 1 or 2, wherein the means is configured to store the operation angle detected by the operation angle detection means over the predetermined time as the neutral angle.
Yaw rate detection means for detecting the yaw rate during travel of the vehicle is provided, and the straight travel determination means determines whether or not the vehicle is traveling straight based on a detection signal detected by the yaw rate detection means. The vehicle steering apparatus according to claim 1 or 2.
A straight travel detection switch for detecting whether or not the vehicle is traveling straight is provided, and the straight travel determination means is configured to determine whether or not the vehicle is traveling straight based on a detection signal from the straight travel detection switch. Item 3. The vehicle steering device according to Item 1 or 2.
A self-propelled vehicle body having a front wheel and a rear wheel, a cargo bed provided on the vehicle body so as to be tiltable with the rear side as a fulcrum and on which a transport object is loaded, and the vehicle body located on the front side of the cargo bed A cab that defines a cab inside, and a hoist cylinder that is provided between the cargo bed and the vehicle body and tilts the cargo bed backward when discharging the object to be transported from the cargo bed,
The vehicle steering apparatus according to claim 1, wherein the steering handle is provided in the cab, the steering cylinder is provided in the front wheel, and the steering valve is provided in the vehicle body.