JP6918654B2 - Work vehicle - Google Patents

Description

The present invention relates to a safety technique for a bending work vehicle such as a wheel loader having a working machine and a bending portion. In particular, it relates to safety technology during work on slopes.

There is a technology to prevent the work vehicle from tipping over while working on slopes. For example, Patent Document 1 states that "a bucket loaded with materials is held at a predetermined height, the vehicle is advanced toward an existing material pile in a material storage area, and the bucket collides with the material pile. It is detected by monitoring the applied load, and if the collision is detected, the bucket is raised and further advanced by a predetermined distance, the bucket is dumped at that position to drop the material on the material pile, and the material is directed toward the material pile. In the process of moving the vehicle forward, it is detected by monitoring the inclination angle of the vehicle that the vehicle rides on the foot of the material mountain, and if an inclination exceeding the vehicle setting is detected, the bucket is placed at that position. The material is dumped to a predetermined height and the material is dropped onto the material pile (abstract excerpt). ”The technique is disclosed.

Japanese Unexamined Patent Publication No. 6-280288

The wheel loader, which is a work vehicle for excavating and loading earth and sand, is a stock pile with earth and sand loaded in a bucket in order to shape the stock pile (storage embankment) that temporarily stores the earth and sand to be loaded. You may climb a steep slope. In this case, depending on the weight and height of the cargo, the inclination of the vehicle, etc., the balance of the entire vehicle may be lost, resulting in instability or rollover.

In the technique disclosed in Patent Document 1, whether or not the vehicle has climbed on the foot of the stock pile is detected by monitoring the inclination angle of the vehicle. Then, when the inclination angle exceeds the set value, the soil is discharged. Therefore, it may not be possible to appropriately determine how unstable the vehicle is depending on the difference in the environment such as the shape of the base of the stock pile.

Further, in the conventional technique as described above, only the ride is detected by monitoring the static inclination angle. Therefore, for example, dynamic instability caused by centrifugal force due to steering operation or acceleration due to control drive operation is not considered. Therefore, in the case of a vehicle that is running or working, the accuracy of determining the possibility of falling is not high.

In view of the above-mentioned conventional problems, it is an object of the present invention to provide a technique for detecting the possibility of a bending work vehicle falling during dynamic work with high accuracy.

In the present invention, the front frame and the rear frame are connected to each other by a center pin, and the vehicle body is provided so as to be bent by the drive of a cylinder, the front wheels provided on the front frame, and the rear frame provided on the rear frame. controlling a wheel, a working machine provided in the front frame, and the vehicle body tilt angle sensor for detecting the inclination angle of the vehicle body, the vehicle body posture based on the inclination angle of the vehicle body detected by the vehicle body inclination sensor In a work vehicle provided with a control device, the control device includes a bending angle sensor for detecting the bending angle formed by the front frame and the rear frame, and a speed sensor for detecting the speed of the work vehicle. An inertial force calculation unit that calculates a vehicle body inertial force, which is an inertial force acting on the vehicle body, based on the bending angle detected by the bending angle sensor and the speed detected by the speed sensor, and a pre-stored vehicle body inertial force calculation unit. based on the center of gravity of the working vehicle calculated by the size and weight, and a vehicle body inertial force calculated by the inertia force calculation section, and the inclination angle of the vehicle body detected by the vehicle body inclination sensor, the inertial force An action point calculation unit that calculates the point where the extension line of the resultant force of gravity acting on the vehicle body and the vehicle body intersects the vehicle support surface as a support force action point, and the point where the front wheels and the rear wheels come into contact with the vehicle support surface. It is provided with a determination unit that determines the rollover possibility based on the support range defined by the support polygon formed by connecting and the support force action point calculated by the action point calculation unit and outputs the determination result. It is characterized by that.

According to the present invention, the possibility of a bending work vehicle falling during dynamic work can be detected with high accuracy. Issues, configurations and effects other than those described above will be clarified by the following description of the embodiments.

It is a side view of the wheel loader of 1st Embodiment. It is a functional block diagram of the rollover prevention device of the first embodiment. (A) and (b) are explanatory views for explaining the rollover determination method of the first embodiment. It is a functional block diagram of the rollover prevention device of the second embodiment. It is a functional block diagram of the rollover prevention device of the third embodiment. (A) and (b) are explanatory views for explaining the rollover determination method of the third embodiment. It is a flowchart of the determination process of the 3rd Embodiment. It is a functional block diagram of the rollover prevention device of 4th Embodiment. It is explanatory drawing for demonstrating the influence degree calculation method of 4th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. The following description shows specific examples of the contents of the present invention, and the present invention is not limited to these explanations. It can be changed and modified. Further, in all the drawings for explaining the present invention, those having the same function may be designated by the same reference numerals, and the repeated description thereof may be omitted.

Further, in the present specification, a wheel loader will be described as an example as a bending work vehicle.

<< First Embodiment >>
In the present embodiment, in addition to the amount of inclination of the vehicle body, the inertial force according to the traveling state of the vehicle is considered in determining the possibility of the vehicle rolling over (overturning). The inertial force is calculated using the acceleration calculated from the amount of state such as acceleration, deceleration, and turning of the vehicle. Design values are used for the center of gravity of the vehicle body used for calculation and judgment.

First, the wheel loader of this embodiment will be described. FIG. 1 is a side view of the wheel loader 100 of the present embodiment. As shown in this figure, the wheel loader 100 is a wheel-type work vehicle including front wheels 104 and rear wheels 105. The wheel loader 100 includes a front frame 101 including a working machine 130 and a rear frame 102 including a driver's seat 113 and an engine as its vehicle body.

The front frame 101 and the rear frame 102 are flexibly connected by a center pin 103. The bending angle formed by the front frame 101 and the rear frame 102 is controlled by the bending hydraulic cylinder 112.

The wheel loader 100 drives the front wheels 104 and the rear wheels 105 fixed to the front frame 101 and the rear frame 102, respectively, to travel forward and backward. Further, steering is performed by angling the front wheels 104 and the rear wheels 105 by bending the vehicle body around the center pin 103. At this time, the turning radius can be freely set by controlling the bending angle.

The driver of the driver's seat 113 controls the control driving force by the accelerator pedal and the brake pedal, and the bending angle by the handle.

The work machine 130 provided on the front frame 101 of the wheel loader 100 loads a load and excavates. The work machine 130 includes a lift arm 107 and a bucket 109 which is a loading unit on which a load is placed. The lift arm 107 and the bucket 109 are rotatably installed around the fulcrum 106 and the fulcrum 108, respectively.

The lift arm 107 is connected to the front frame 101 at a fulcrum 106. By supporting the rotation angle of the lift arm 107 by the hydraulic cylinder 110, the lift arm 107 supports the load of the bucket 109 and changes its height. The bucket 109 is connected to the lift arm 107 at a fulcrum 108. Like the lift arm 107, the bucket 109 can also have its rotation angle variable by a hydraulic cylinder (not shown). With this configuration, the height and angle of the bucket 109, which is the loading portion, can be freely manipulated.

Further, the wheel loader 100 of the present embodiment includes a lift angle detection sensor 201, a bucket angle detection sensor 202, a load load detection sensor 203, a vehicle body bending angle detection sensor 204, a vehicle body speed detection sensor 205, and a vehicle body tilt angle. It includes a detection sensor 206.

The lift angle detection sensor 201 detects the angle (lift angle) of the lift arm 107 with respect to the front frame 101. The lift angle detection sensor 201 is provided at, for example, a fulcrum 106.

The bucket angle detection sensor 202 detects the angle (bucket angle) of the bucket 109 with respect to the lift arm 107. The bucket angle detection sensor 202 is provided at, for example, a fulcrum 108.

The lift angle detection sensor 201 and the bucket angle detection sensor 202 detect the position and orientation of the loading portion (bucket 109) on which the load is placed.

The load load detection sensor 203 detects the weight of the bucket 109. The load load detection sensor 203 is installed in, for example, the hydraulic cylinder 110. The lift arm 107 and the bucket 109 on which the load is placed are connected to the front frame 101 at a fulcrum 106, and are supported by the hydraulic cylinder 110 to support the load of the bucket 109. Therefore, the load can be detected by the load load detection sensor 203 installed on the hydraulic cylinder 110. As the load load detection sensor 203, for example, a pressure sensor that measures the cylinder pressure on the bottom side (the side that supports the load) of the hydraulic cylinder 110 is used.

The vehicle body bending angle detection sensor 204 detects the bending angle. The vehicle body bending angle detection sensor 204 is provided, for example, on the center pin 103 or the bending hydraulic cylinder 112. The vehicle body bending angle detection sensor 204 is realized by, for example, a rotary encoder that detects the rotation angle of the center pin 103. Further, the detector may be a detector that detects the cylinder lengths of the bending hydraulic cylinders 112 provided on the left and right sides of the center pin 103 and converts them into bending angles.

The vehicle body speed detection sensor 205 detects the speed of the wheel loader 100. The vehicle body speed detection sensor 205 is provided on the rear wheel 105, for example, and detects the rotational speed of the wheel and converts it into a speed.

The vehicle body tilt angle detection sensor 206 detects the vehicle body tilt angle of the wheel loader 100. The vehicle body tilt angle detection sensor 206 is provided, for example, in the lower part of the driver's seat 113 of the rear frame 102.

The lift angle detection sensor 201, the bucket angle detection sensor 202, and the load load detection sensor 203 are not used in the rollover detection device described later in this embodiment. Therefore, in this embodiment, it is not necessary to provide these sensors.

Further, as shown by x and z in the figure, in the present embodiment, the direction opposite to the gravity direction is the z direction, and the axle direction of the rear wheel 105 is the y direction on the same plane in a plane orthogonal to the z direction. A coordinate system is used in which the direction orthogonal to the y direction is the x direction. The origin is, for example, the design center of gravity of the vehicle. The same coordinate system is used in other embodiments.

Further, the wheel loader 100 of the present embodiment includes a control system that performs various controls such as steering control, vehicle speed control, work equipment control, position detection, communication, and rollover prevention. The control system takes in sensor signals from sensors provided in each part of the vehicle body, performs processing according to a predetermined control algorithm, and outputs drive signals to various actuators (control units).

The control system of this embodiment includes a CPU, a memory, and a storage device. The CPU realizes the above processing by expanding the program stored in the storage device into the memory and executing the program. In addition, all or a part of the functions may be realized by hardware such as ASIC (Application Specific Integrated Circuit) and FPGA (field-programmable gate array).

Hereinafter, the rollover detection function of the control system will be mainly described. The rollover detection device 200 that realizes the rollover detection function of the present embodiment performs processing based on the signals output from the above sensors attached to the wheel loader 100, determines the possibility of rollover, and outputs the determination result. do.

Specifically, in the present embodiment, the running state of the vehicle, that is, the speed of the vehicle detected by the vehicle body speed detection sensor 205, the state quantity such as the turning radius based on the bending angle detected by the vehicle body bending angle detection sensor 204, and the like. Based on, the inertial force acting on the center of gravity of the vehicle is calculated. Then, the possibility of rollover is determined by adding the inertial force.

FIG. 2 is a functional block diagram of the rollover detection device 200 of the present embodiment that realizes the above functions. As shown in this figure, the vehicle rollover detection device 200 of the present embodiment is connected to the vehicle body bending angle detection sensor 204, the vehicle body speed detection sensor 205, and the vehicle body inclination angle detection sensor 206 attached to the vehicle. ..

The rollover detection device 200 of the present embodiment includes an inertial force calculation unit 208, an action point calculation unit 209, a support range calculation unit 210, and a determination unit 211.

The inertial force calculation unit 208 calculates the inertial force acting on the center of gravity of the vehicle. For the calculation, the speed of the vehicle detected by the vehicle body bending angle detection sensor 204 and the bending angle of the vehicle body detected by the vehicle body speed detection sensor 205 are used.

The inertial force is calculated by first calculating the acceleration at the center of gravity of the vehicle and then integrating the weight of the vehicle there. Acceleration includes front-rear acceleration generated by a controlling driving force and centrifugal acceleration generated in the lateral direction with turning.

The acceleration in the front-rear direction is obtained by pseudo-differentiating the speed of the vehicle detected by the vehicle body speed detection sensor 205, for example. For example, the control drive torque may be estimated based on the engine torque output, the brake fluid pressure, or the like, and the acceleration may be calculated using the estimation.

The centrifugal acceleration a is calculated by the following equation (1) using the turning speed v and the turning radius r when the vehicle makes a circular motion.
a = v2 / r ... (1)

The inertial force calculation unit 208 adds these accelerations in the front-rear direction and centrifugal acceleration as vectors, integrates the vehicle weight, and calculates the inertial force vector. Design information is used for the vehicle weight.

The action point calculation unit 209 calculates the direction of the resultant force of the inertial force and the gravity as the bearing force action point. In the present embodiment, first, the action point calculation unit 209 calculates the direction of gravity acting in the vertical direction with respect to the vehicle body by using the inclination angle of the vehicle body detected by the vehicle body inclination angle detection sensor 206. Then, the direction of the resultant force is calculated using the direction of gravity and the inertial force vector.

Then, a bearing force action point is obtained as an intersection with the road surface of a line extending from the center of gravity of the vehicle to the road surface in the direction of the resultant force.

The support range calculation unit 210 uses the bending angle detected by the vehicle body bending angle detection sensor 204 to obtain the ground contact points of the four tires. The vehicle body of the wheel loader 100 is supported by these four grounding points. These four grounding points are set as support points, and the polygonal region surrounded by these support points is set as the support range.

The determination unit 211 determines whether or not the wheel loader 100 may roll over. In the present embodiment, the determination unit 211 compares the bearing force action point calculated by the action point calculation unit 209 with the support range calculated by the support range calculation unit 210, and the bearing force action point is inside the support range. The possibility of rollover is judged by whether or not. That is, if the bearing force action point is inside the support range, it is determined that there is no possibility of rollover, and if it is outside, it is determined that there is a possibility of rollover.

3A and 3B are diagrams schematically showing an example of a determination method by the determination unit 211. FIG. 3A will be described with reference to a front view of the wheel loader 100 for the sake of simplicity. Further, in FIG. 3B, a view viewed from above will be used for description.

The support range 305 is determined by the positions of the four wheels calculated by the support range calculation unit 210 based on the bending angle detected by the vehicle body bending angle detection sensor 204, that is, the four support points 308.

Further, the bearing force action point 307 is an intersection with the road surface 311 of a line extending the direction of the resultant force 306, which is the sum of the vectors of the inertial force 303 and the gravity 304, to the road surface 311. Reference numeral 302 denotes the center of gravity of the vehicle (center of gravity of the vehicle).

The support range 305 is a polygonal region surrounded by four support points as described above. Therefore, the direction of the resultant force 306 is obtained by similarly considering the paper surface depth direction (x direction).

As described above, the determination unit 211 determines the possibility of rollover depending on whether or not the bearing force action point 307 is inside the support range 305. In the example of FIG. 3A, the bearing force acting point 307 is inside the supporting range 305 (supporting point 308) (on the center of gravity side of the vehicle weight). Therefore, the determination unit 211 determines that there is no possibility of rollover and outputs the determination result.

However, if the inertial force or the vehicle body tilt angle increases even a little from the state shown in FIG. 3A, the bearing force action point 307 goes out of the supporting range 305. The situation in this case is shown in FIG. 3 (b).

As shown in FIG. 3B, when the bearing force acting point 307 is outside the supporting range 305 (supporting point 308), the determination unit 211 determines that there is a possibility of rollover and outputs the determination result. do.

In the present embodiment, the determination result by the determination unit 211 may be output to, for example, a notification means, various vehicle body control means, and the like.

As described above, in the wheel loader 100 which is the bending type work vehicle of the present embodiment, the front frame 101 and the rear frame 102 are connected to each other by the center pin 103 and bent by the drive of the cylinder (hydraulic cylinder 110). The vehicle body provided in the front frame 101, the front wheels 104 provided in the front frame 101, the rear wheels 105 provided in the rear frame 102, the working machine 130 provided in the front frame 101, and the road surface 311 (vehicle support). The posture of the vehicle body is controlled based on the vehicle body tilt angle sensor (vehicle body tilt angle detection sensor 206) that detects the vehicle body tilt angle which is the vehicle body tilt angle with respect to the surface) and the vehicle body tilt angle detected by the vehicle body tilt angle sensor. In the wheel loader 100 provided with the control device, the bending angle sensor (vehicle body bending angle detection sensor 204) for detecting the bending angle formed by the front frame 101 and the rear frame 102 and the speed of the wheel loader 100 are detected. A speed sensor (vehicle body speed detection sensor 205) is provided, and the control device is an inertial force acting on the vehicle body based on the bending angle detected by the bending angle sensor and the speed detected by the speed sensor. The inertial force calculation unit 208 for calculating the vehicle body inertial force, the center of gravity point of the work vehicle calculated by the dimensions and weight of the vehicle body stored in advance, and the vehicle body inertial force calculated by the inertial force calculation unit 208. Based on the vehicle body tilt angle detected by the vehicle body tilt angle sensor, the action of calculating the point where the extension line of the resultant force of the inertial force and the gravity acting on the vehicle body intersects the vehicle support surface is calculated as the support force action point 307. The support range defined by the support polygon formed by connecting the point calculation unit 209 and the points where the front wheels 104 and the rear wheels 105 are in contact with the vehicle support surface, and the support force calculated by the action point calculation unit 209. A determination unit 211 that determines the possibility of overturning based on the point of action 307 and outputs the determination result is provided.

As described above, according to the present embodiment, the acceleration around the center of gravity of the vehicle is calculated based on the running state of the wheel loader 100, that is, the amount of states such as whether the vehicle is accelerating or decelerating or turning. do. Further, the acceleration and the weight of the vehicle are integrated to calculate the inertial force acting on the center of gravity of the vehicle. The position of the center of gravity of the vehicle and the weight of the vehicle used at this time are obtained as design information.

On the other hand, gravity also acts on the center of gravity of the vehicle. However, the direction changes depending on the inclination of the vehicle. In the present embodiment, the direction of gravity is also calculated by detecting the vehicle body tilt angle.

In the present embodiment, the point where the extension line of the resultant force between the inertial force acting on the center of gravity of the vehicle and the gravity intersects the road surface 311 is defined as the bearing force acting point 307. The resultant force of these inertial forces and gravity is supported by the support point 308 of the vehicle, that is, the ground contact point by the four tires. Therefore, in the present embodiment, the rollover possibility is determined based on whether or not the bearing force acting point 307 is inside the supporting range 305, which is a polygonal region surrounded by the four supporting points 308.

Therefore, according to the present embodiment, it is possible to determine the possibility of rollover with high accuracy in consideration of not only the magnitude of the inclination of the slope on which the vehicle travels but also the traveling state such as acceleration / deceleration and turning of the vehicle. Then, when the vehicle travels on a slope, the possibility of falling can be detected at an early stage regardless of the degree of slope, the approach angle to the slope, the bending angle of the vehicle body, and the height of the load.

That is, according to the present embodiment, the possibility of rollover is determined in consideration of the inertial force. Therefore, it is possible to determine the possibility of rollover with high accuracy, particularly with respect to the wheel loader operating on a slope.

In the present embodiment, the possibility of rollover is determined based on whether or not the bearing force action point 307 is within the supporting range 305, but the present invention is not limited to this. For example, a predetermined determination range may be set inside the support range 305, and the determination may be performed depending on whether or not the bearing force action point 307 is within the determination range.

<< Second Embodiment >>
Next, a second embodiment of the present invention will be described. In the first embodiment, a design value based on the dimensions of the vehicle body and the weight of the vehicle body is used as the center of gravity of the vehicle. On the other hand, in the second embodiment, the center of gravity (calculated center of gravity) calculated in consideration of the load of the load and the state (position and posture) of the bucket as the loading portion is used in addition to the dimensions of the vehicle body and the weight of the vehicle body.

The wheel loader 100 of this embodiment basically has the same configuration as that of the first embodiment. However, the function of the rollover detection device is different. Hereinafter, the wheel loader 100 of the present embodiment will be described with a focus on a configuration different from that of the first embodiment.

FIG. 4 is a functional block diagram of the rollover detection device 200a of the present embodiment. As shown in this figure, the rollover detection device 200a of the present embodiment includes an inertial force calculation unit 208, an action point calculation unit 209, a support range calculation unit 210, a determination unit 211, and a center of gravity calculation unit 207.

Further, in the rollover detection device 200a of the present embodiment, in addition to the vehicle body bending angle detection sensor 204, the vehicle body speed detection sensor 205, the vehicle body inclination angle detection sensor 206, and the lift angle detection sensor 201, which are attached to the vehicle. , The bucket angle detection sensor 202, and the load load detection sensor 203 are connected.

The function of the inertial force calculation unit 208 and the function of the determination unit 211 are the same as those in the first embodiment.

The center of gravity calculation unit 207 calculates the center of gravity of the wheel loader 100 in the operating posture in which the load is loaded. In the present embodiment, first, the position and orientation of the bucket 109 are calculated. Then, using the position of the bucket 109, the weight of the load, and the position and weight of the center of gravity of the front frame 101, the position and weight of the center of gravity of the entire front frame 101 including the load and the working machine 130 are calculated. After that, the position and weight of the center of gravity of the rear frame 102 are further added to calculate the weight of the entire vehicle and the position of the center of gravity. Design information is used for the position and weight of the center of gravity of the front frame 101 and the position and weight of the center of gravity of the rear frame 102.

The action point calculation unit 209 uses the position of the center of gravity point calculated by the center of gravity calculation unit 207 instead of the position of the center of gravity of the design information. Other processing is the same as that of the first embodiment.

Hereinafter, the procedure for calculating the center of gravity by the center of gravity calculation unit 207 will be described.

First, the center of gravity calculation unit 207 geometrically calculates the position and orientation of the bucket 109 using the lift angle, the bucket angle, and the link length of the lift arm 107. Design information is used for the link length of the lift arm 107.

Next, the center of gravity calculation unit 207 calculates the position and weight of the center of gravity point of the entire front frame 101 by using the load load detected by the load load detection sensor 203 and the position and posture of the bucket 109.

Here, the coordinate value (hereinafter, simply referred to as a position) of the position of the center of gravity point (point 120 in FIG. 1) of the bucket 109 is set to G0 (x0, z0), and the center of gravity point (point 121 in FIG. 1) of the front frame 101 is set. ) Is G1 (x1, z1). Further, the weight of the cargo of the bucket 109 is M0, and the weight of the front frame 101 is M1.

Note that M0 is a value detected by the load load detection sensor 203. Further, design information is used for M1.

The positions of the weight Mf and the center of gravity Gf (xf, zf) of the entire front frame 101 are represented by the internal division points of G0 and G1. That is, it is obtained by the following equations (2) to (4).
Mf = M0 + M1 ... (2)
xf = (M0 ・ x0 + M1 ・ x1) / Mf ・ ・ ・ (3)
zf = (M0 ・ z0 + M1 ・ z1) / Mf ・ ・ ・ (4)

The vehicle lateral direction (y-axis direction; depth direction in FIG. 1) is also obtained in the same manner. For example, assuming that the cargo is evenly loaded, the position of the center of gravity in the lateral direction of the vehicle (here, the y-coordinate yf) may be the center of the vehicle.

Next, the center of gravity calculation unit 207 uses the position and weight of the center of gravity of the entire front frame 101 including the load and the working machine 130 and the position and weight of the center of gravity of the rear frame 102 to obtain the total weight of the vehicle body and the entire vehicle. Calculate the center of gravity of.

The position of the center of gravity point (point 122 in FIG. 1) of the rear frame 102 is G1 (xr, zr), and the weight of the rear frame 102 is Mr. These use design information. Using these, the gross vehicle weight Mc and the vehicle center of gravity point Gc (xc, zc) can be calculated by the following equations (5) to (7).
Mc = Mf + Mr ... (5)
xc = (Mf ・ xf + Mr ・ xr) / Mc ・ ・ ・ (6)
zc = (Mf ・ zf + Mr ・ zr) / Mc ・ ・ ・ (7)

When the vehicle body is bent at the center pin 103, the symmetry is lost in the left-right direction of the vehicle. In this case, using the y-coordinate yf of the entire front frame 101 and the y-coordinate yr of the position G1 of the center of gravity of the rear frame 102, the y-coordinate yc of the vehicle center of gravity Gc is calculated by the equations (6) and (7). It is calculated by the following equation (8) by the equation of the internal division point in the same manner as in the above equation.
yc = (Mf ・ yf + Mr ・ yr) / Mc ・ ・ ・ (8)

In the above procedure, the center of gravity calculation unit 207 calculates the coordinates of the center of gravity. Then, the action point calculation unit 209 of the present embodiment uses the center of gravity for the calculation of the bearing force action point 307.

As described above, in the wheel loader 100 of the present embodiment, the working machine 130 includes a lift arm 107 and a bucket 109. Further, the wheel loader 100 further detects a lift angle detection sensor 201 that detects a lift angle that is an angle of the lift arm 107 with respect to the vehicle body, and a bucket angle that is an angle of the bucket 109 with respect to the lift arm 107. The wheel loader 100 is based on the bucket angle detection sensor 202, the load load detection sensor 203 that detects the load of the load loaded on the bucket 109, the lift angle, the bucket angle, the load, and the bending angle. A center of gravity calculation unit 207 that calculates the vehicle center of gravity as the calculation center of gravity is provided. Then, the point of action calculation unit 209 uses the calculated center of gravity as the center of gravity.

As described above, according to the present embodiment, the lift angle detection sensor 201 and the bucket angle detection sensor 202 that detect the position and attitude of the bucket 109, which is the loading portion on which the load is loaded, are further provided. The working machine 130 portion having the bucket 109, which is a loading portion, is configured so that the position and orientation of the bucket 109 can be changed by a link mechanism. The position and posture can be uniquely calculated by the angle of the lift arm 107 with respect to the vehicle body and the angle of the bucket with respect to the lift arm 107.

In the present embodiment, first, the position of the cargo with respect to the front frame 101 is calculated using the respective angles obtained by the lift angle detection sensor 201 and the bucket angle detection sensor 202. Further, the load weight detection sensor 203 is provided in the working machine 130 portion to detect the weight of the load. Using the position and weight of the load with respect to the front frame 101 and the position and weight of the center of gravity of the front frame 101 known as design information, the position and weight of the center of gravity of the entire front frame 101 including the load are calculated. do.

On the other hand, the position and weight of the center of gravity of the rear frame 102 are also known as design information, and the positional relationship is the angle obtained by the vehicle body bending angle detection sensor 204 and the position of the center pin 103 connecting the front frame 101 and the rear frame 102. It can be calculated uniquely by. Therefore, in the present embodiment, the position and weight of the center of gravity of the entire vehicle can be calculated with high accuracy by using the bending angle of the vehicle body and the position and weight of the center of gravity of the front and rear parts of the vehicle body.

Inertial force and gravity are used to determine the possibility of rollover. All of these act in a size proportional to the weight of the vehicle with respect to the position of the center of gravity of the vehicle. Therefore, by calculating the position of the center of gravity of the vehicle and the weight with high accuracy, it is possible to determine the risk of rollover with high accuracy regardless of the position and posture of the bucket 109 which is the loading portion and the size of the bending angle of the vehicle body.

As described above, according to the present embodiment, the rollover possibility is determined in consideration of the inertial force as in the first embodiment. Therefore, in particular, the rollover possibility can be determined with high accuracy with respect to the operating wheel loader 100.

Further, according to the present embodiment, the center of gravity is calculated based on the detection values of the lift angle detection sensor 201, the bucket angle detection sensor 202, and the load load detection sensor 203 in this way. Therefore, the position of the center of gravity can be calculated with high accuracy. Then, since the rollover possibility is determined using the position of the center of gravity, the rollover possibility can be determined more accurately.

The inertial force calculation unit 208 may also use a value obtained by adding the load as the vehicle weight when calculating the inertial force.

<< Third Embodiment >>
Next, a third embodiment of the present invention will be described. In the present embodiment, the output is changed according to the determination result of the determination unit. Hereinafter, the present embodiment will be described with a focus on a configuration different from that of the first embodiment.

The wheel loader 100 of this embodiment is basically the same as that of the first embodiment. However, the wheel loader 100 of the present embodiment further includes a vehicle body bending angle control unit 213, a driving force control unit 214, and a notification unit 215.

Further, as shown in FIG. 5, the rollover detection device 200b of the present embodiment has the same configuration as that of the second embodiment. However, the processing content and output destination of the determination unit 211 are different.

The vehicle body bending angle control unit 213 controls the vehicle body bending angle according to the output from the rollover detection device 200b. Specifically, a control command is output to the bending hydraulic cylinder 112.

The driving force control unit 214 controls the driving force according to the output from the rollover detection device 200. In this embodiment, for example, the maximum speed is controlled. Specifically, the driving force is controlled by controlling a driving unit such as an accelerator or a brake.

The determination unit 211 determines the possibility of falling and outputs the determination result. In the first embodiment, it is determined only whether or not the bearing force action point 307 is within the bearing range 305. However, in the present embodiment, a plurality of ranges (regions) are further set within the support range 305, and the determination result is output to different output destinations according to the positional relationship between each range and the support force action point 307.

The determination method of the determination unit 211 will be described with reference to FIGS. 6 (a), 6 (b), and 7. 6 (a) and 6 (b) are diagrams for explaining a plurality of ranges of the present embodiment, and FIG. 7 is a processing flow of determination processing.

In the present embodiment, as shown in FIG. 6A, the first range 610 and the second range 620 are set within the support range 305. The second range 620 is set so that its outer circumference is arranged between the outer circumference of the first range 610 and the support range 305.

When the determination unit 211 receives the support force action point 307 from the action point calculation unit 209 and the support range 305 from the support range calculation unit 210, the determination unit 211 starts the determination process shown in FIG. 7.

First, the determination unit 211 determines whether or not the bearing force action point 307 is within the first range 610 (step S1101). Then, when the bearing capacity action point 307 is within the first range 610, nothing is output as there is no possibility of rollover, and the determination process ends. In this determination, the term "within the first range 610" includes the case where the bearing capacity action point 307 is on the boundary line between the first range 610 and the second range 620. Hereinafter, the same shall apply in each determination of the present embodiment. The determination when the bearing force action point 307 is on the boundary line is not limited to this, and may be determined in advance.

Next, when the bearing force action point 307 is outside the first range 610, the determination unit 211 determines whether or not it is within the second range 620 (step S1102). When it is within the second range 620 (S1102; Yes), the determination unit 211 outputs the first determination result to the notification unit 215 (step S1103), and ends the process. For example, the notification unit 215 that has received the first determination result outputs an alarm.

Next, when the bearing force action point 307 is outside the second range 620, the determination unit 211 determines whether or not it is within the supporting range 305 (step S1104). When it is within the support range 305 (S1104; Yes), the determination unit 211 outputs the second determination result to the driving force control unit 214 (step S1105), and ends the process. The second determination result is, for example, a drive command that limits the maximum speed. Upon receiving the drive command, the driving force control unit 214 performs drive control so that the vehicle does not reach a speed higher than the maximum speed specified by the drive command.

Then, when the bearing force action point 307 is outside the supporting range 305 (S1104; No), the determination unit 211 outputs a third determination result to the vehicle body bending angle control unit 213 (step S1106), and ends the process. .. The third determination result is, for example, a bending angle control command that limits the maximum value of the vehicle body bending angle. Upon receiving the bending angle command, the vehicle body bending angle control unit 213 controls the operation of the bending hydraulic cylinder 112 so that the vehicle body bending angle does not exceed the maximum value.

The determination unit 211 repeats the above process every time the bearing force action point 307 is received from the action point calculation unit 209.

FIG. 6B shows the relationship between the support range determined by the determination unit 211 and the support force action point 307. FIG. 6B is a schematic diagram cut out by a straight line including the projection 301 of the center of gravity of the vehicle on the xy plane of FIG. 6A and the bearing force action point 307, and plotting the fall risk on the vertical axis. Here, the support range 305 indicates the fall limit defined by the contact patch 312 of the four tires, and indicates the highest risk. The second range 620 and the first range 610 are inside the support range 305, indicating that the risk decreases toward the inside. Since the bearing force action point 307 is outside the bearing range 305, the risk is high, which corresponds to the third determination result in FIG. 7.

As described above, the wheel loader 100 of the present embodiment further includes a notification unit 215 that outputs a warning to the outside, and in the determination unit 211, the bearing force action point 307 is the first inside the supporting range 305. If it is outside the range 610, the first determination is output to the notification unit 215 as the determination result, and the notification unit 215 outputs the warning when the first determination is received.

Further, a driving force control unit 214 for controlling the drive of the wheel loader 100 is further provided, and the determination unit 211 has the bearing force acting point 307 outside the first range 610 inside the supporting range 305. If it is within the second range 620, the second determination is output to the driving force control unit 214 as the determination result, and when the driving force control unit 214 receives the second determination, the maximum speed is limited. The second range 620 is within the support range 305 and outside the first range 610.

Further, the vehicle body bending angle control unit 213 for controlling the bending angle is provided, and the determination unit 211 makes a third determination as the determination result when the bearing force action point is outside the second range 620. When the output is output to the bending angle control unit 213 and the vehicle body bending angle control unit 213 receives the third determination, the upper limit bending angle is limited.

As described above, according to the present embodiment, the rollover possibility is determined in consideration of the inertial force as in the first embodiment. Therefore, it is possible to determine the possibility of rollover with high accuracy, particularly with respect to the wheel loader in operation.

Further, according to the present embodiment, instead of determining whether or not the product is inside the support range 305, a plurality of ranges are provided inside the support range 305, and in a plurality of steps according to the distance from the boundary of the support range 305. Judge the possibility of rollover. Then, the optimum output is performed according to the stage to control the vehicle. Therefore, according to the present embodiment, it is possible to realize control that achieves both safety and operability.

In this embodiment, the alarm output, the maximum speed limit, and the bending angle limit are all described, but the present invention is not limited to this. It may be configured to control only 1 or 2 of these. Further, in step S1105, the bending angle may be limited, and in S1106, the maximum speed limiting process may be performed. Further, when the maximum speed limit and the bending angle limit are performed, an alarm output may be performed at the same time. At this time, the mode of the alarm to be output may be changed.

Further, although the case where two ranges are provided within the support range 305 has been described as an example, the number of ranges to be set is not limited to this.

<< Fourth Embodiment >>
Next, a fourth embodiment of the present invention will be described. In the present embodiment, the control amount is calculated according to the positional relationship between the bearing force action point 307 and the support range 305, and the wheel loader 100 is controlled so that the bearing force action point 307 is within the support range 305. The control targets are, for example, a driving force and a vehicle body bending angle. By changing these, the bearing force action point 307 is made to be inside the support range 305, that is, the bearing force action point 307 is made as close to the center of gravity of the vehicle as possible.

Hereinafter, the configuration for realizing the present embodiment will be described with a focus on a configuration different from that of the third embodiment.

The wheel loader 100 of this embodiment basically has the same configuration as that of the first embodiment. Further, the rollover detection device 200c of the wheel loader 100 of the present embodiment basically has the same configuration as that of the third embodiment. However, as will be described later, the control amount calculation unit 212 is further provided, and the processing content and output destination of the determination unit 211 are different.

FIG. 8 is a functional block diagram of the rollover detection device 200c of the present embodiment. As shown in this figure, the rollover detection device 200c of the present embodiment further includes a control amount calculation unit 212 in the configuration of the second embodiment.

When the control amount calculation unit 212 determines that the bearing force action point 307 is outside the support range 305, the control amount calculation unit 212 changes at least one of the driving force and the vehicle body bending angle so that the bearing force action point 307 is within the support range 305. Is calculated. At this time, the control amount calculation unit 212 uses the output of the vehicle body tilt angle detection sensor 206 and the output of the inertial force calculation unit 208.

In the present embodiment, the control amount calculation unit 212 first calculates the degree of influence of shifting the bearing force action point 307 from the vehicle center of gravity 302 for each of the inertial force and the gravity. The outline of the calculation method will be described with reference to FIG.

First, as shown in FIG. 9, in the vehicle body horizontal plane (xy plane in FIG. 9) with respect to the vehicle body of the wheel loader 100, the directions connecting the projections 501 and 507 of the vehicle center of gravity and the bearing force action points, respectively. Define the unit vector. Then, the magnitudes of the components in the unit vector direction of each of the inertial force 503 and the gravity 504 are calculated, and this is used as the degree of influence. Specifically, the scalar value obtained by the inner product of the unit vector, the inertial force 503, and the gravity 504 is the above-mentioned degree of influence.

Then, the control amount calculation unit 212 compares the degree of influence of the inertial force with the degree of influence of gravity, and controls so as to preferentially reduce the one having the larger degree of influence.

First, a method for reducing the inertial force will be described. The method for reducing the inertial force differs depending on whether the main force generating the inertial force is centrifugal force or acceleration.

When the main force that generates the inertial force is the centrifugal force, the vehicle body speed is reduced or the turning radius is increased in order to reduce the centrifugal force.

The vehicle body speed can be reduced by reducing the driving force by reducing the engine output or by operating the brake to increase the braking force. Therefore, in this case, the control amount calculation unit 212 outputs the control amount as a control command to the driving force control unit 214.

The control amount is calculated so that the bearing force action point 307 falls within the bearing range 305. First, the magnitude of the inertial force 503 in which the projection 507 of the bearing force action point 307 falls within the supporting force range 305 is calculated. Then, the vehicle body speed that realizes this is calculated as the target speed. The control amount is obtained as the difference between the current speed and the target speed. As for the current speed, the detection value of the vehicle body speed detection sensor 205 is acquired via the inertial force calculation unit 208.

In order to increase the turning radius, the bending angle of the vehicle body is reduced. In this case, the control amount calculation unit 212 outputs the control amount as a control command to the vehicle body bending angle control unit 213. The control amount is calculated so that the bearing force action point 307 falls within the bearing range 305. Similar to the vehicle body speed, the difference between the current turning radius and the target turning radius is calculated as the control amount. The vehicle body bending angle, which is the basis for calculating the current turning radius, is obtained by acquiring the detection value of the vehicle body bending angle detection sensor 204 via the inertial force calculation unit 208.

As shown in the equation (1), the centrifugal force is proportional to the square of the speed and inversely proportional to the turning radius. Therefore, in this case, it is desirable to give priority to the reduction of the vehicle body speed.

When the inertial force is acceleration / deceleration, acceleration / deceleration by the controlling driving force is limited. The situation to which this is applied is, for example, the case of descending while braking a steep descent. In this case, the control amount calculation unit 212 outputs the control amount as a control command to the driving force control unit 214. The control amount is calculated by the above-mentioned method so that the bearing force action point 307 falls within the bearing range 305.

On the other hand, when the influence of gravity is smaller than the influence of inertial force, control is performed to reduce the influence of the vehicle body tilt angle.

In this case, in order to reduce the influence of the vehicle body inclination angle, the vehicle body direction is directed to the maximum inclination direction and the inclination in the vehicle left-right direction is reduced. In order to realize this, for example, the vehicle body is bent in the direction opposite to the direction of gravity 504. Therefore, the control amount calculation unit 212 outputs the control amount as a control command to the vehicle body bending angle control unit 213. The control amount is calculated so that the bearing force action point 307 falls within the bearing range 305. The current vehicle body tilt angle used at this time is acquired from the vehicle body tilt angle detection sensor 206.

As described above, according to the present embodiment, the driving force control unit 214 that controls the drive of the wheel loader 100, the vehicle body bending angle control unit 213 that controls the bending angle, and the driving force of the wheel loader 100. Further, the control amount calculation unit 212 for controlling the bending angle is further provided, and the control amount calculation unit 212 sets the bearing force action point within a predetermined region within the supporting range according to the determination result. At least one of the driving force and the bending angle is controlled.

As described above, according to the present embodiment, when it is determined that the possibility of rollover is high as a result of determining the possibility of rollover, the point of action of the bearing force, which is the resultant force of the inertial force and gravity, is the supporting range 305. At least one of the driving force and the vehicle body bending angle is changed in the direction toward the inside of.

For example, the centrifugal force is an inertial force generated in a direction away from the turning center by turning. The magnitude of the centrifugal force is proportional to the square of the vehicle body speed and inversely proportional to the turning radius. When the support point of action is moved to the outside of the support range by this centrifugal force, the vehicle body speed is reduced as the first countermeasure. In this case, the driving force is reduced or set to a negative value (braking force is generated). Also, as a second measure, increase the turning radius. In this case, the risk of rollover is reduced by reducing the bending angle of the vehicle body.

Further, when the bearing force action point 307 moves to the outside of the supporting range 305 due to the excessive inclination angle of the vehicle body, the bending angle of the vehicle body is changed so as to be within the allowable range to change the direction of the vehicle body. ..

As described above, according to the present embodiment, the possibility of rollover can be accurately and effectively reduced by changing the driving force and the vehicle body bending angle based on the vehicle body inertial force and the vehicle body tilt angle.

Further, in the present embodiment, the determination unit 211 may further output the determination result to the notification unit 215. In this case, the above control is performed and an alarm is also output. The alarm may be output in different modes depending on the stage of the determination result and the control content.

The third and fourth embodiments have been described by taking the case of combining with the second embodiment as an example, but the present invention is not limited thereto. For example, it may be combined with the first embodiment.

Further, the fourth embodiment may be combined with the third embodiment. In this case, when the support point of action is outside any of the support range 305, the second range 620, and the first range 610, the above control is performed.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and there are design changes and the like within a range that does not deviate from the gist of the present invention. Also, they are included in the present invention.

100: wheel loader, 101: front frame, 102: rear frame, 103: center pin, 104: front wheel, 105: rear wheel, 106: fulcrum, 107: lift arm, 108: fulcrum, 109: bucket, 110: hydraulic cylinder , 112: Hydraulic cylinder for bending, 113: Driver's seat, 130: Working machine,
200: Rollover detection device, 200a: Rollover detection device, 200b: Rollover detection device, 200b: Rollover detection device, 200c: Rollover detection device,
201: Lift angle detection sensor, 202: Bucket angle detection sensor, 203: Load load detection sensor, 204: Body bending angle detection sensor, 205: Body speed detection sensor, 206: Body inclination angle detection sensor, 207: Center of gravity calculation unit, 208: inertial force calculation unit, 209: action point calculation unit, 210: support range calculation unit, 211: judgment unit, 212: control amount calculation unit, 213: vehicle body bending angle control unit, 214: driving force control unit, 215: Notification unit,
301: Projection of the center of gravity of the vehicle, 302: Center of gravity of the vehicle, 303: Inertial force, 304: Gravity, 305: Support range, 306: Interconnective force, 307: Supporting point of action, 308: Supporting point, 311: Road surface, 312: Ground plane ,
501: Projection of the center of gravity of the vehicle, 503: Inertial force, 504: Gravity, 507: Projection of bearing force action point, 610: First range, 620: Second range

Claims (6)

A vehicle body provided so that the front frame and the rear frame are connected to each other by a center pin and bent by driving a cylinder.
The front wheels provided on the front frame and
The rear wheels provided on the rear frame and
The work machine provided on the front frame and
A vehicle body tilt angle sensor that detects the vehicle body tilt angle , and
In a work vehicle provided with a control device that controls the posture of the vehicle body based on the inclination angle of the vehicle body detected by the vehicle body inclination angle sensor.
A bending angle sensor that detects the bending angle formed by the front frame and the rear frame,
A speed sensor for detecting the speed of the work vehicle is provided.
The control device is
An inertial force calculation unit that calculates a vehicle body inertial force, which is an inertial force acting on the vehicle body, based on the bending angle detected by the bending angle sensor and the speed detected by the speed sensor.
The center of gravity point of the work vehicle calculated from the dimensions and weight of the vehicle body stored in advance, the vehicle body inertial force calculated by the inertial force calculation unit, and the inclination angle of the vehicle body detected by the vehicle body tilt angle sensor. Based on the above, the point of action calculation unit that calculates the point where the extension line of the resultant force of the inertial force and the gravity acting on the vehicle body intersects the vehicle support surface as the support force action point.
Rollover possibility based on the support range defined by the support polygon formed by connecting the points where the front wheels and the rear wheels come into contact with the vehicle support surface and the support force action point calculated by the action point calculation unit. A work vehicle characterized in that it is provided with a determination unit that determines and outputs a determination result. The work vehicle according to claim 1.
The working machine is equipped with a lift arm and a bucket.
The work vehicle further
A lift angle detection sensor that detects the lift angle, which is the angle of the lift arm with respect to the vehicle body,
A bucket angle detection sensor that detects a bucket angle, which is an angle of the bucket with respect to the lift arm,
A load load detection sensor that detects the load of the load loaded on the bucket, and
Based on the lift angle detected by the lift angle detection sensor, the bucket angle detected by the bucket angle detection sensor, the load detected by the load load detection sensor, and the bending angle detected by the bending angle sensor. A work vehicle including a center of gravity calculation unit for calculating the center of gravity point of the work vehicle. The work vehicle according to claim 1 or 2.
It also has a notification unit that outputs a warning to the outside.
When the bearing force acting point is outside the first range within the supporting range, the determination unit outputs the first determination as the determination result to the notification unit.
A work vehicle characterized in that the notification unit outputs the warning when the first determination is received. The work vehicle according to claim 1 or 2.
Further equipped with a driving force control unit that controls the driving of the work vehicle,
When the supporting force action point is outside the first range within the supporting range and within the second range, the determination unit makes a second determination to the driving force control unit as the determination result. Output and
Upon receiving the second determination, the driving force control unit limits the maximum speed.
The work vehicle, wherein the second range is within the support range and outside the first range. The work vehicle according to claim 4.
A bending angle control unit for controlling the bending angle is further provided.
When the bearing force action point is outside the second range, the determination unit outputs a third determination as the determination result to the bending angle control unit.
The work vehicle characterized in that the bending angle control unit limits the upper limit bending angle when the third determination is received. The work vehicle according to any one of claims 1 to 3.
A driving force control unit that controls the driving of the work vehicle,
A bending angle control unit that controls the bending angle,
A control unit that controls the driving force and bending angle of the work vehicle is further provided.
The control unit controls at least one of the driving force and the bending angle so that the supporting force acting point is within a predetermined region within the supporting range according to the determination result. ..

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