JP7245723B2 - Truck bed center-of-gravity position control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a truck bed center-of-gravity position control device that achieves overturn prevention.

Conventionally, as a vehicle overturn prevention technology, a first sensor and a second sensor, which are displacement sensors, and an acceleration sensor are installed in a truck in order to detect lateral acceleration, which is the tilt of the loading platform during travel. and A controller communicating with these sensors is provided, and when the detected value exceeds a set value, a controlled lift amount is calculated based on the detected value so that the cargo bed does not overturn. There is known a truck rollover prevention device that is provided with an actuator connected to a controller, tilts a cargo bed according to a controlled lift amount, and substantially suppresses a lateral force that occurs when the cargo bed tilts outward (see, for example, Patent Document 1). ).

In addition, a chassis frame tilt sensing device is provided at an appropriate position on the chassis frame to detect the lateral tilt of the chassis frame. A switching valve is interposed in each of the pair of air pipes of a pair of pressing bodies and an air tank, and when the chassis frame tilts, the pressing body on the side close to the axle is actuated. (See Patent Document 2, for example).

JP-A-5-124543 Japanese Utility Model Laid-Open No. 62-146610

However, in the device described in Patent Document 1, tilt displacement information of the bed is used as a reference, and when the bed is detected to be tilted, control is performed to tilt the bed according to the control lift amount. Therefore, when the change speed of the tilt displacement of the bed is high or when the tilt displacement direction of the bed changes, the control response for tilting the bed following these changes is delayed. In addition, since a pair of left and right actuators that support the bed are controlled, there is a problem that the amount of movement of the center of gravity of the bed is small relative to the amount of control, and effective rollover prevention cannot be achieved.

On the other hand, in the device described in Patent Document 2, the control is based on the input information from the chassis frame tilt sensing device. As in Document 1, there is a problem that the amount of movement of the center of gravity of the loading platform is small relative to the amount of control, and effective rollover prevention cannot be achieved.

The present invention has been made with a focus on the above-mentioned problems. In a scene where the frame tilt angle changes, active control is performed to move the center of gravity of the loading platform with good response to the change in the frame tilt angle. The purpose is to achieve prevention.

In order to achieve the above objects, the present invention provides a truck in which a loading platform is mounted on a chassis frame on which tires are suspended, comprising an equalizer mechanism, an actuator, a frame tilt angle sensor, a controller, a hydraulic unit, Prepare.
The equalizer mechanism is interposed between the chassis frame and the cargo bed, and axially supports the cargo bed so as to be swingable in the lateral direction of the vehicle with respect to the chassis frame.
The actuator is provided in the equalizer mechanism, and drives and changes the lateral inclination angle of the loading platform based on an external control command.
A frame tilt angle sensor detects a frame tilt angle at which the chassis frame is tilted with respect to a horizontal plane.
When the controller starts tilt angle control of the bed, the controller uses the frame tilt angle sensor value input from the frame tilt angle sensor at regular time intervals as a reference, and follows the change in the frame tilt angle sensor value to shift the center of gravity of the bed to the left and right tires. An active control command is output to the actuator to obtain the target bed tilt angle toward the center position of the ground clearance.
The hydraulic unit has an oil pump and an accumulator as a hydraulic source, and has a plurality of types of flow control valves with different valve operating speeds when controlling the flow rate of pressurized hydraulic oil from the accumulator.
The actuator is a pair of left and right hydraulic cylinders that expand and contract by pressurized hydraulic oil supplied from a flow control valve provided in the hydraulic unit.
The controller detects a value whose tilt direction is opposite to the frame tilt angle sensor value input from the frame tilt angle sensor at regular time intervals and whose tilt angle absolute value is the same as that of the frame tilt angle sensor value. Calculate as angle target value. Then, the equalizer movement angle is calculated based on the target bed tilt angle, and among the multiple types of flow control valves, when the equalizer movement angle is greater than a predetermined angle, a flow control valve with a high valve operating speed is selected, and the equalizer A flow control valve with a lower valve operating speed is selected as the movement angle is smaller, and an active control command is output to the selected valve.

Since the above problem-solving means is adopted, effective rollover prevention can be achieved by performing active control that moves the center of gravity of the loading platform with good response to changes in the frame inclination angle in scenes where the frame inclination angle changes. . Then, even when the vehicle is traveling on an uneven road surface where the frame tilt angle changes from side to side, the cargo bed can be maintained in a horizontal position regardless of the lateral swing of the chassis frame. In addition, multiple types of flow control valves with different valve operating speeds are prepared, and by selecting the flow control valve with the appropriate valve operating speed according to the equalizer movement angle, the response delay of the equalizer movement and the fluctuation of the cargo bed are prevented. It is possible to achieve compatibility with

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an overall side view showing a dump trailer of a tractor and dump trailer vehicle to which the bed center-of-gravity position control device of Embodiment 1 is applied; FIG. 4 is a configuration explanatory diagram showing a front equalizer mechanism; FIG. 4 is a configuration explanatory diagram showing a rear equalizer mechanism; FIG. 4 is a rear view of the trailer showing the lateral tilt range of the loading platform by the front equalizer mechanism and the rear equalizer mechanism; It is a hydraulic circuit diagram showing a hydraulic unit configuration of a dump cylinder. FIG. 3 is a hydraulic circuit diagram showing the configuration of hydraulic units for hydraulic cylinders provided in the front equalizer mechanism and the rear equalizer mechanism; FIG. 2 is a control system block diagram showing a control system configuration of the platform center-of-gravity position control device; 4 is a flow chart showing the flow of a bed center-of-gravity position control process executed by a controller; FIG. 10 is an operation explanatory view showing the operation of moving the center of gravity of the loading platform away from the center position of the left and right tire ground clearance to the downward slope side when the dump trailer travels/stops on a sloped road surface in the background art. FIG. 10 is an operation explanatory view showing an operation that the center of gravity of the loading platform approaches the central position of the left and right tire grounding distance when the dump trailer travels/stops on a road sloped downward to the right in the first embodiment; FIG. 4 is an operation explanatory view showing the operation of the center of gravity of the loading platform approaching the center position of the left and right tire ground clearance when the dump trailer travels/stops on a left-sloping sloping road surface in the first embodiment;

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the center-of-gravity position control apparatus of the truck|truck of this invention is demonstrated based on Example 1 shown in drawing.

The bed center-of-gravity position control device in the first embodiment is applied to a tractor and dump trailer vehicle (an example of a dump truck), which is a coupled truck capable of separating a tractor (towing vehicle) equipped with an engine and a dump trailer (towed vehicle). applied. Hereinafter, the configuration of the first embodiment will be described by dividing it into "dump trailer configuration", "hydraulic unit configuration", "control system configuration", and "load bed center-of-gravity position control processing configuration".

[Dump trailer configuration (Figs. 1 to 4)]
As shown in FIG. 1, the dump trailer T includes a chassis frame 1, tires 2, a loading platform 3 (called a "vessel"), a tailgate 4, a dump cylinder 5, and a front equalizer mechanism 6 (equalizer mechanism ) and a rear equalizer mechanism 7 (equalizer mechanism).

The chassis frame 1 is a body frame structure of the dump trailer T, and includes a tractor connecting portion 1a extending toward the front portion of the frame, a frame body portion 1b on which the loading platform 3 is mounted, and a body portion 1b provided at the rear end of the frame. and a rear bumper portion 1c.

The tire 2 is a triple tire that is suspended from the chassis frame 1 and arranged three in a row in the vehicle front-rear direction as viewed from the side. Between the chassis frame 1 and the tire 2, an axle-suspension type suspension using a leaf spring (not shown) is interposed.

The loading platform 3 is centered on a dump spindle S set at a lower position on the rear end side of the loading platform, and is parallel to the chassis frame 1. 3′) is installed to be tiltable. The shape of the rear end surface of the loading platform 3 is an inclined rear end surface shape that becomes rearward of the vehicle as it goes from the top end of the loading platform toward the bottom side of the loading platform.

The tailgate 4 is rotatably suspended by a hinge pin provided on the rear upper portion of the cargo bed 3, and closes in contact with the inclined rear end surface when the cargo bed 3 is in a horizontal state. When the tailgate 4 is unlocked, the lower end surface of the gate opens downward according to the tilt angle of the loading platform 3 when the loading platform 3 tilts backward. Closing locking and unlocking of the tailgate 4 are performed by an air cylinder (not shown) provided on the back surface of the rear end side of the cargo bed 3 .

The dump cylinder 5 is supported at its upper end by a vehicle width direction pin on the front end of the loading platform 3, and is supported by a vehicle width direction pin on a loading platform side bracket 63 of the front equalizer mechanism 6 at its lower end. The dump cylinder 5 allows the front end of the loading platform 3 to move up and down around a dumping support shaft S set at the rear of the loading platform 3 . Also, the front end of the loading platform 3 can be swung via the dump cylinder 5 .

The front equalizer mechanism 6 is interposed between the tractor connecting portion 1a (front portion) of the chassis frame 1 and the lower end side of the dump cylinder 5, and rocks the cargo bed 3 in the lateral direction with respect to the chassis frame 1 at the front portion of the trailer. Axially supported for movement. The front equalizer mechanism 6 includes a frame-side bracket 61, a front equalizer shaft 62, a carrier-side bracket 63, a right hydraulic cylinder 64, and a left hydraulic cylinder 65, as shown in FIG.

The frame-side bracket 61 is fixed to the tractor connecting portion 1a of the chassis frame 1. As shown in FIG. The front equalizer shaft 62 is the center axis of swinging of the carrier-side bracket 63 with respect to the frame-side bracket 61, and is set at the position of the vehicle center line CL. The carrier-side bracket 63 is pivotally supported by the frame-side bracket 61 so as to be swingable, and the lower end side of the dump cylinder 5 is fixed. The right hydraulic cylinder 64 is arranged by connecting the right end of the frame-side bracket 61 and the right end of the carrier-side bracket 63 with pin support. The left hydraulic cylinder 65 is arranged by connecting the left end of the frame-side bracket 61 and the left end of the carrier-side bracket 63 by pin support.

The rear equalizer mechanism 7 is interposed between the rear portion of the chassis frame 1 and the rear portion of the cargo bed 3, and axially supports the cargo bed 3 with respect to the chassis frame 1 in the lateral direction of the vehicle at the rear portion of the trailer. The rear equalizer mechanism 7 includes a frame-side bracket 71, a rear equalizer shaft 72, a carrier-side bracket 73, a right hydraulic cylinder 74, and a left hydraulic cylinder 75, as shown in FIG.

The frame-side bracket 71 is fixed to the lower rear end position of the chassis frame 1 . The rear equalizer shaft 72 is the center axis of swinging of the carrier-side bracket 73 with respect to the chassis frame 1 , and is set at the vehicle center line CL of the chassis frame 1 . The loading platform side bracket 73 is fixed to the bottom surface of the loading platform 3 and axially supported to be swingable with respect to the chassis frame 1 . The right hydraulic cylinder 74 is arranged by connecting the right end of the frame-side bracket 71 and the right end of the carrier-side bracket 73 with pin support. The left hydraulic cylinder 75 is arranged by connecting the left end portion of the frame side bracket 71 and the left end portion of the carrier side bracket 73 by pin support.

A pair of left and right hydraulic cylinders 64, 65 of the front equalizer mechanism 6 and a pair of left and right hydraulic cylinders 74, 75 of the rear equalizer mechanism 7 are driven to change the lateral inclination angle of the cargo bed 3 based on an external control command. It is an example of an actuator. By driving the actuator, as shown in FIG. 4, the cargo bed 3 swings about both equalizer shafts 62 and 72, and the right side of the vehicle center line CL becomes the right tilt angle control range θ(R) of the cargo bed 3. The left side of the vehicle center line CL is the left tilt angle control range θ(L) of the loading platform 3 . The center of gravity G of the bed moves in the vehicle width direction as the bed 3 swings around the equalizer shafts 62 and 72, and the right movement control range G(R) of the center of gravity G of the bed is to the right of the vehicle center line CL. , and the left side of the vehicle center line CL is the left movement control range G(L) of the center of gravity G of the bed. That is, if both equalizer shafts 62 and 72 are arranged below the vehicle center line CL within a range that can be established as a layout design, the lower the vehicle center line CL, the larger the vehicle width direction movement amount of the center of gravity G of the loading platform can be secured. .

[Hydraulic unit configuration (Figs. 5 and 6)]
The hydraulic units mounted on the vehicle include a dump cylinder hydraulic unit 8 that controls the hydraulic pressure supplied to the dump cylinder 5, and a hydraulic cylinder hydraulic unit 9 that controls the hydraulic pressure supplied to the hydraulic cylinders 64, 65, 74, and 75. prepared independently of each other.

The dump cylinder hydraulic unit 8 is a hydraulic unit for manually switching supply (extension)/discharge (reduction) of pressurized hydraulic oil. As shown in FIG. A valve 83 , a control valve 84 , a normally open solenoid 85 , a one-way solenoid valve 86 and a filter 87 are provided. Here, the control valve 84 is a valve that switches the direction of flow by manually operating the dump lever 88 . A normally open solenoid 85 is a valve that is shut off during fail-safe processing. The one-way solenoid valve 86 is a valve that allows only shortening of the dump cylinder 5 by discharging pressurized hydraulic oil during fail-safe processing.

The hydraulic unit 9 for hydraulic cylinders is a hydraulic unit in which pressurized hydraulic oil is supplied and discharged according to a control command. As shown in FIG. , a pressure switch 95 , an accumulator 96 , a high pressure filter 97 , a poppet valve 98 and a filter 99 . Here, the accumulator 96 ensures a stable supply of pressurized hydraulic oil to the hydraulic cylinders 64, 65, 74, 75 regardless of the upper limit discharge amount from the oil pump 93 driven by the on-vehicle power source. is provided. The accumulator 96 is installed in an empty space on the back side of the chassis frame 1 or the like.

The hydraulic unit 9 for hydraulic cylinders includes a front control valve unit 100 and a rear control valve unit 101 which are solenoid-driven and controlled by control commands output from the controller 10 . The front control valve unit 100 includes a directional control valve 100a that switches the flow direction of pressurized hydraulic oil, a first flow control valve 100b that operates at a low speed, and a second flow control valve 100c that operates at a medium speed. , and a third flow control valve 100d having a high valve operating speed. The rear control valve unit 101 includes a directional control valve 101a that switches the flow direction of pressurized hydraulic oil, a first flow control valve 101b that operates at a low speed, and a second flow control valve 101c that operates at a medium speed. , and a third flow control valve 101d having a high valve operating speed. As each flow control valve, a proportional solenoid valve whose flow rate is controlled in proportion to the solenoid command value is used.

That is, the hydraulic unit 9 for hydraulic cylinders has an oil pump 93 and an accumulator 96 as a hydraulic source, and three types of flow control valves with different valve operating speeds when controlling the flow rate of pressurized hydraulic oil from the accumulator 96. It is a hydraulic unit.

Further, in the hydraulic circuit of the hydraulic unit 9 for hydraulic cylinders, as shown in FIG. 6, the input/output ports of the front control valve unit 100 and the input/output ports of the hydraulic cylinders 64 and 65 are cross-connected. Similarly, the input/output ports of the rear control valve unit 101 and the input/output ports of the hydraulic cylinders 74 and 75 are cross-connected. Due to this cross connection, during tilt angle control of the cargo bed 3, one hydraulic cylinder is hydraulically extended and the other cylinder is hydraulically shortened in synchronism. The hydraulic operation response speed of mechanisms 6 and 7 is increased.

[Control system configuration (Fig. 7)]
In the tilt angle control of the loading platform 3, the controller 10 includes an input sensor that acquires sensor information, an input switch that acquires switch information, an output element that outputs a control command after arithmetic processing based on the acquired information, and the like. It has

Input sensors include a front proximity sensor 11, a rear proximity sensor 12, a front frame tilt angle sensor 13, a rear frame tilt angle sensor 14, a front bed tilt angle sensor 15, and a rear bed tilt angle sensor 16. I have.

A front proximity sensor 11 detects a first dump angle at which tilt angle control of the loading platform 3 is terminated and shifts to storage operation control by switching a switch signal when the loading platform 3, which is rising, descends. The rear proximity sensor 12 detects a second dump angle at which tilt angle control of the loading platform 3 is started when the horizontal loading platform 3 starts to rise by switching a switch signal. Note that the first dump angle and the second dump angle are made different in order to prevent control hunting (first dump angle>second dump angle).

The front frame tilt angle sensor 13 detects the frame tilt angle at which the front portion of the chassis frame 1 is tilted with respect to the horizontal plane. The rear frame tilt angle sensor 14 detects the frame tilt angle at which the rear portion of the chassis frame 1 is tilted with respect to the horizontal plane.

The front bed tilt angle sensor 15 detects the bed tilt angle at which the front portion of the bed 3 is tilted with respect to the horizontal plane. A rear loading platform tilt angle sensor 16 detects the loading platform tilt angle at which the rear portion of the loading platform 3 is tilted with respect to the horizontal plane. As the bed tilt angle sensors 15 and 16, for example, encoder type sensors are used.

Input switches include a main switch 17 , a lever operation switch 18 , a forward rotation tilt angle manual operation button 19 , and a reverse rotation tilt angle manual operation button 20 .

The main switch 17 is a switch for starting/ending tilt angle control of the loading platform 3 in the automatic control mode, is provided in the display device 21 described later, and outputs a switch signal (PTO signal) when turned on. The lever operation switch 18 is a switch for detecting the start/end of the dump operation. A forward tilt angle manual operation button 19 and a reverse tilt angle manual operation button 20 are buttons to be operated when controlling the tilt angle of the loading platform 3 in the manual control mode, and are provided on a display device 21 which will be described later.

As output elements, a front control valve unit 100, a rear control valve unit 101, a display device 21, a buzzer 22, a lamp 23, a normally open solenoid 85, and a one-way solenoid valve 86 are provided.

The front control valve unit 100 and the rear control valve unit 101 are operated by a tilt angle control command for the loading platform 3 output from the controller 10 . The front control valve unit 100 has a directional control valve 100a, a first flow control valve 100b, a second flow control valve 100c, and a third flow control valve 100d. The rear control valve unit 101 has a directional control valve 101a, a first flow control valve 101b, a second flow control valve 101c, and a third flow control valve 101d.

The display device 21 is installed, for example, at a position in the cabin that is easily visible to the driver, and visually appeals specific control content information and control change information during tilt angle control of the loading platform 3 according to a display command from the controller 10. displayed. The screen of the display device 21 has, for example, an icon display section, a frame angle display section, a bed angle display section, a valve operation speed display section, and the like. The display method is also divided into "front equalizer" and "rear equalizer" by switching the display screen.

A buzzer 22 gives an audible indication that the damping is rising, a failure level, or the like. The lamp 23 lights up in blue to indicate that the automatic control is in operation, and lights up in red or flashes to warn of a failure. A normally open solenoid 85 and a one-way solenoid valve 86 regulate damping ascent in fail-safe processing according to a command output from the controller 10 .

That is, the control system is configured to have an "automatic control mode" and a "manual control mode". When the "automatic control mode" is selected, the front control valve unit 100 and the rear control valve unit 101 are automatically operated by active control commands from the controller 10 based on input information. When the "manual control mode" is selected, the front control valve unit 100 and the rear control valve unit 101 are operated by control commands from the controller 10 based on button operation.

[Balance center position control processing configuration (Fig. 8)]
FIG. 8 is a flow chart showing the flow of the bed center-of-gravity position control process executed by the controller 10, and each step will be described below. It should be noted that the center-of-gravity position control process of the loading platform is started by turning on the main switch 17 . When the tilt angle control of the loading platform 3 (loading platform balancing operation) is started, a series of control processes from input to output are repeated at predetermined time intervals (control cycle).

In step S1, subsequent to the start, it is determined based on the signal from the lever operation switch 18 whether or not the dump operation start has been detected. If YES (dump operation start detected), the process proceeds to step S2, and if NO (dump operation start not detected), the determination of step S1 is repeated.

In step S2, following the determination in step S1 that the start of the dumping operation has been detected, it is determined whether or not the dumping cylinder 5 has detected the front end portion of the loading platform 3 rising due to the first dumping angle or more based on the signal from the rear proximity sensor 12. to decide. In the case of YES (loading platform rise detected), the process proceeds to step S3, and in the case of NO (loading platform rise not detected), the process returns to step S1.

In step S3, following the judgment in step S2 that the cargo bed has been raised (the control start condition is established), the front frame tilt angle sensor 13, the rear frame tilt angle sensor 14, the front bed tilt angle sensor 15, and the rear bed tilt angle are detected. The inclination angle information from the sensor 16 is read, and the process proceeds to step S4.

In step S4, following the reading of the tilt angle information in step S3, a display command is output to the display device 21, and the process proceeds to step S5.

In step S5, following the output of the display command in step S4, the frame tilt angle sensor values input from the frame tilt angle sensors 13 and 14 at regular time intervals are used as a reference, and changes in the frame tilt angle sensor values are followed. A target bed tilt angle is calculated so that the center of gravity G of the bed 3 moves toward the central position of the ground clearance W between the left and right tires, and the process proceeds to step S6. In the calculation of the target bed tilt angle, the target bed tilt angle on the front side and the target bed tilt angle on the rear side are calculated separately.

In step S6, following the calculation of the bed tilt angle target value in step S5, an equalizer movement angle (hereinafter abbreviated as "EQ movement angle") is calculated based on the bed tilt angle target value, and the process proceeds to step S7.

In step S7, following the calculation of the EQ movement angle in S6, it is determined whether or not the EQ movement angle exceeds the first set angle θ1. If YES (EQ movement angle>θ1), proceed to step S8, and if NO (EQ movement angle≦θ1), return to step S3. Note that the first set angle θ1 is set, for example, to about ±1 degree.

In step S8, following the judgment in S7 that the EQ movement angle>θ1, it is judged whether or not the EQ movement angle is equal to or less than the second set angle θ2. If YES (EQ movement angle≦θ2), proceed to step S9, and if NO (EQ movement angle>θ2), proceed to step S10. Note that the second set angle θ2 is set, for example, to about ±2 degrees.

In step S9, following the determination in S8 that the EQ movement angle ≤ θ2, the first flow control valves 100b and 101b with low valve operating speeds are selected as flow control valves for outputting control commands. Then, an active control command for obtaining a target bed tilt angle on the front side is output to the first flow control valve 100b, and an active control command for obtaining a target bed tilt angle on the rear side is output to the first flow control valve 101b. output and proceed to step S13.

In step S10, it is determined whether or not the EQ movement angle is equal to or less than the third set angle .theta.3, following the determination in S8 that the EQ movement angle>.theta.2. If YES (EQ movement angle≦θ3), the process proceeds to step S11, and if NO (EQ movement angle>θ3), the process proceeds to step S12. Note that the third set angle θ3 is set, for example, to about ±3 degrees.

In step S11, following the determination in step S10 that the EQ movement angle ≤ θ3, the second flow control valves 100c and 101c with medium valve operating speeds are selected as flow control valves for outputting control commands. Then, an active control command for obtaining a target bed tilt angle on the front side is output to the second flow control valve 100c, and an active control command for obtaining a target bed tilt angle on the rear side is output to the second flow control valve 101c. output and proceed to step S13.

In step S12, following the judgment in S10 that the EQ movement angle>θ3, the third flow control valves 100d and 101d with high valve operating speeds are selected as flow control valves for outputting control commands. Then, an active control command for obtaining a target bed tilt angle on the front side is output to the third flow control valve 100d, and an active control command for obtaining a target bed tilt angle on the rear side is output to the third flow control valve 101d. output and proceed to step S13.

In step S13, following the output of the active control command in S9, S11 or S12, it is determined whether or not the bed tilt angle from the front bed tilt angle sensor 15 or the rear bed tilt angle sensor 16 is equal to or less than the abnormality determination threshold. . If YES (cargo bed tilt angle≦abnormality determination threshold value), the process proceeds to step S14, and if NO (cargo bed tilt angle>abnormality determination threshold value), the process proceeds to step S17. That is, during the tilt angle control of the bed 3, the bed tilt angle (the bed tilt angle sensor value) is monitored, and if the bed tilt angle≦abnormality determination threshold, the bed tilt angle control is continued.

In step S14, following the determination in step S13 that the bed tilt angle≦abnormality determination threshold, the dump cylinder 5 detects that the front end portion of the bed 3 is lowered due to the second dump angle or less based on the signal from the front proximity sensor 11. determine whether it did. In the case of YES (loading platform lowering detected), the process proceeds to step S15, and in the case of NO (loading platform lowering not detected), the process returns to step S3. In other words, the detection of the lowering of the front end of the loading platform 3 by the second dumping angle or less is a condition for ending the inclination angle control of the loading platform 3 and a condition for starting the storage operation control of the loading platform 3 .

In step S15, following the determination in step S14 that the bed has been lowered, the storage operation control of the bed 3 is executed to set the deviation angle between the frame inclination angle and the bed inclination angle to zero degrees, and the process proceeds to step S16.

In step S16, it is determined whether or not the main switch 17 is off following the storage operation control in S15 or the execution of the fail-safe process in S18. If YES (main switch OFF), proceed to END. If NO (main switch ON), repeat the determination of S16.

In step S17, following the determination in S13 that the bed tilt angle>abnormality determination threshold, a warning is issued by buzzer 22 or lamp 23 according to the level of divergence between the bed tilt angle and the abnormality determination threshold, and the process proceeds to step S18.

In step S18, following the warning in step S17, the tilt angle control of the loading platform 3 is switched from the "automatic control mode" to the "manual control mode", and the dump cylinder 5 cannot be raised, but only allowed to descend.Fail-safe processing is executed. and proceed to step S16.

Next, "problems of the background art and measures for solving the problems" will be described. Then, the operation of the first embodiment will be described by dividing it into "load bed center-of-gravity position control processing operation" and "load-bed center-of-gravity position control operation".

[Problems of the background art and solutions to the problems (Fig. 9)]
As a vehicle overturn prevention device, various technologies have been proposed in patent publications and the like, but they have not yet spread to the stage of general practical use. Therefore, the dump trailer as the background art has a chassis frame on which tires are suspended and a loading platform that can be raised and lowered, and does not control the tilt angle of the loading platform.

In a scene of unloading earth and sand with a dump trailer of the background art, if the road surface at the work site has large unevenness, for example, in the case of a road surface that slopes downward to the right as shown in FIG. Sometimes I end up At this time, the center of gravity G of the loading platform near the center position of the left and right tire grounding interval W on the horizontal road surface moves toward the right tire grounding line T1 on the low road surface side, such as moving to the center of gravity G' of the loading platform. As the dumping angle of the loading platform is increased in order to drop earth and sand from the opening of the tailgate, the loading platform gravity center G' rises to the loading platform gravity center G'', and further moves toward the right tire grounding line T1. In addition, when the earth and sand are dropped from the slanted platform, if the earth and sand are unevenly distributed on the right side, the center of gravity G″ of the platform moves further toward the right tire grounding line T1.

Therefore, in a scene where earth and sand are to be unloaded with a dump trailer while traveling forward at low speed, the cargo bed is tilted due to unevenness of the road surface, and when the center of gravity G of the cargo bed exceeds the right tire grounding line T1, the right tire grounding point P1 is reached. The dump trailer will overturn around the center. Similarly, when the center of gravity G of the loading platform exceeds the left tire grounding line T2, the dump trailer rolls over around the left tire grounding point P2. This overturning of the dump trailer has a problem that even a skilled driver cannot avoid overturning because the inclination of the loading platform cannot be controlled by the driver during unloading work.

The inventor of the present invention verified the mechanism when the loading platform tilts due to unevenness of the road surface, etc., and found that (tires contacting the road surface) → (chassis frame on which the tires are suspended) → (loading platform mounted on the frame) ) shows a tilting mechanism in which the behavior changes due to a slight difference in response time. In addition, by verifying the adoption of a mechanism that supports the cargo bed so that it can be tilted by a pair of left and right actuators, even if the expansion and contraction control of the pair of left and right actuators is performed, the cargo bed will only tilt due to turning around the center of gravity of the cargo bed. It was found that the position of the center of gravity of the loading platform itself hardly moves in the vehicle width direction.

Based on the above findings, the present invention provides a truck (dump trailer T) in which a loading platform 3 is mounted on a chassis frame 1 on which tires 2 are suspended, and which includes equalizer mechanisms 6 and 7, actuators (hydraulic cylinders 64 and 65 , 74, 75), frame tilt angle sensors 13, 14, and a controller 10. The equalizer mechanisms 6 and 7 are interposed between the chassis frame 1 and the loading platform 3, and axially support the loading platform 3 with respect to the chassis frame 1 so as to be swingable in the lateral direction of the vehicle. Actuators (hydraulic cylinders 64, 65, 74, 75) are provided in the equalizer mechanisms 6, 7, and drive and change the lateral inclination angle of the cargo bed 3 based on control commands from the outside. Frame tilt angle sensors 13 and 14 detect the frame tilt angle at which the chassis frame 1 is tilted with respect to the horizontal plane. When the controller 10 starts tilt angle control of the loading platform 3, the controller 10 follows the change in the frame tilt angle sensor value based on the frame tilt angle sensor value input from the frame tilt angle sensors 13 and 14 at regular time intervals. A means for solving the problem of outputting an active control command for obtaining a target tilt angle of the bed so that the center of gravity G of the bed moves toward the center position of the ground clearance W between the left and right tires is adopted to the actuators (hydraulic cylinders 64, 65, 74, 75).

That is, when the tilt angle control of the bed 3 is started, the controller 10 obtains the target bed tilt angle based on the frame tilt angle sensor values input from the frame tilt angle sensors 13 and 14 at regular time intervals. there is For this reason, when performing active control of the bed tilt angle, by using the tilt information of the chassis frame 1 that can sense the change in behavior before the bed 3, the control response speed is faster than using the tilt information of the bed 3. becomes higher.

On the other hand, in order to effectively reflect the active control configuration in the controller 10 when aiming to prevent overturning, a hardware configuration that follows changes in the frame tilt angle sensor value and moves the center of gravity G of the bed with high response is required. requested. Therefore, as a hardware configuration, the equalizer mechanisms 6 and 7 that can ensure a large amount of movement of the center of gravity G of the loading platform with respect to the amount of actuator control are employed. Therefore, by selecting the equalizer mechanisms 6 and 7 as the hardware configuration, the movement response speed of the center of gravity G of the loading platform becomes higher than when, for example, a mechanism that supports the loading platform with a pair of left and right actuators is selected as the hardware configuration.

As a result, in a scene where the frame tilt angle changes, effective rollover prevention can be achieved by performing active control that moves the center of gravity G of the loading platform with good response to changes in the frame tilt angle.

[Operation of load platform center of gravity position control processing (Fig. 8)]
When the main switch 17 is turned on and the conditions for starting the dumping operation and the conditions for raising the bed are established, the process proceeds to S1→S2→S3→S4→S5→S6→S7 in the flow chart of FIG. Control (cargo bed balancing operation) is started.

In S3, the tilt angle information from the front frame tilt angle sensor 13, the rear frame tilt angle sensor 14, the front bed tilt angle sensor 15, and the rear bed tilt angle sensor 16 is read. A display command is output to the display device 21 in S4. In step S5, the frame tilt angle sensor values input from the frame tilt angle sensors 13 and 14 at regular time intervals are used as a reference, and the center of gravity G of the loading platform is moved to the center of the left and right tire ground clearance W following changes in the frame tilt angle sensor values. A bed tilt angle target toward position is calculated. Here, the target bed tilt angle is the direction of tilt opposite to the front frame tilt angle sensor value input from the frame tilt angle sensors 13 and 14 at regular time intervals, and the direction of tilt is opposite to the frame tilt angle sensor value. The absolute value of the tilt angle is the same value. In other words, in the tilt angle control of the loading platform 3, the angle that keeps the loading platform 3 horizontal regardless of the frame inclination angle is calculated as a target value, and the loading platform balancing operation that keeps the loading platform 3 horizontal with respect to changes in the frame inclination angle is performed. .

In S6, an EQ movement angle is calculated based on the target bed tilt angle. In S7, it is determined whether or not the EQ movement angle exceeds the first set angle θ1, and while the EQ movement angle≦θ1 is maintained, the flow of S3→S4→S5→S6→S7 is repeated. It is set as a control dead zone in which tilt angle control is not performed.

On the other hand, when the EQ movement angle>θ1, the process proceeds from S7 to S8, and in S8, it is determined whether or not the EQ movement angle is equal to or less than the second set angle θ2. When it is determined in S8 that θ1<EQ movement angle≦θ2, the process proceeds to S9, in which the first flow control valves 100b and 101b with low valve operating speeds are selected as flow control valves for outputting active control commands. be.

If it is determined in S8 that the EQ movement angle>.theta.2, the process proceeds from S8 to S10, in which it is determined whether or not the EQ movement angle is equal to or less than the third set angle .theta.3. When it is determined in S10 that θ2<EQ movement angle≦θ3, the process proceeds to S11, in which the second flow control valves 100c and 101c having medium valve operating speeds are selected as flow control valves for outputting active control commands. be done.

When it is determined in S10 that the EQ movement angle>θ3, the process proceeds from S10 to S12, and in S12, the third flow control valves 100d and 101d having high valve operating speeds are selected as flow control valves for outputting control commands. . In this manner, in S6 to S12, control is performed to output the active control command by switching flow control valves having different operating speeds according to the magnitude of the EQ movement angle.

In S13, following the output of the active control command in S9, S11, or S12, it is determined whether or not the bed tilt angle from the front bed tilt angle sensor 15 or the rear bed tilt angle sensor 16 is equal to or less than the abnormality determination threshold. be. If it is determined in S13 that the bed tilt angle≦abnormality determination threshold is satisfied, the process proceeds to S14. It is determined whether or not the lowering of the front end of the loading platform 3 by the second dumping angle or less has been detected. As long as the lowering of the loading platform is not detected, the process returns from S14 to S3, and the tilt angle control of the loading platform 3 (loading platform balancing operation) in S3 to S12 is continued. However, when it is determined in S13 that the bed tilt angle>abnormality determination threshold value, the process proceeds to S17. In response, a warning is issued by the buzzer 22 and the lamp 23, and in the next step S18, the tilt angle control of the loading platform 3 is switched from the "automatic control mode" to the "manual control mode", and the dump cylinder 5 cannot be raised and only lowered. is executed (fail-safe processing), and control is terminated by proceeding to the end.

On the other hand, when the lowering of the bed is detected in S14, the process proceeds to S15, in which storage operation control of the bed 3 is executed to set the deviation angle between the frame tilt angle and the bed tilt angle to zero degrees. In the next step S16, it is determined whether or not the main switch 17 is turned off.

[Operation for controlling the position of the center of gravity of the loading platform (Figs. 10 and 11)]
When the dump trailer T travels/stops on a road surface sloping downward to the right, the chassis frame 1 may tilt greatly to the right as shown in FIG. At this time, the center of gravity of the loading platform, which has been near the center position of the left and right tire contact gap W on the horizontal road surface, tries to move to a position near the right tire grounding line T1 (the position of the center of gravity G' of the loading platform). However, by controlling the position of the center of gravity of the loading platform toward the central position of the left and right tire contact gap W, the movement of the center of gravity is suppressed to a position (the position of the center of gravity G1 of the loading platform) farther from the right tire contact line T1 than the center of gravity G' of the loading platform. Then, the change in the right tilt angle of the chassis frame 1 is followed, and the cargo bed balancing operation for keeping the cargo bed 3 horizontal is performed.

Therefore, even if the dumping angle of the loading platform 3 is increased, the loading platform gravity center G1 rises to the loading platform gravity center G1' without changing the divergence distance from the right tire grounding line T1. do. In addition, when the earth and sand are dropped from the flat bed 3, the earth and sand drop and move without being unevenly distributed. Nor.

Therefore, in a scene where earth and sand are unloaded with a dump trailer while traveling forward at low speed, even if the chassis frame 1 tilts to the right due to the unevenness of the road surface, the center of gravity G1 of the loading platform exceeds the right tire contact line T1. is avoided, the dump trailer T is prevented from overturning around the right tire contact point P1.

When the dump trailer T travels/stops on a road surface that slopes downward to the left, the chassis frame 1 may tilt greatly to the left as shown in FIG. 11 . At this time, the center of gravity of the loading platform, which has been near the center position of the left and right tire contact gap W on the horizontal road surface, tries to move to a position near the left tire grounding line T2 (the position of the center of gravity G' of the loading platform). However, by controlling the position of the center of gravity of the loading platform toward the central position of the right-and-left tire contact gap W, the movement of the center of gravity is suppressed to a position (the position of the center of gravity G2 of the loading platform) farther from the left tire contact line T2 than the center of gravity G' of the loading platform. Then, the change in the left tilt angle of the chassis frame 1 is followed, and the cargo bed balancing operation for keeping the cargo bed 3 horizontal is performed.

Therefore, even if the dumping angle of the bed 3 is increased, the bed center of gravity G2 rises to the bed center of gravity G2' without changing the divergence distance from the left tire grounding line T2. do. In addition, when the earth and sand are dropped from the flat bed 3, the earth and sand drop and move without being unevenly distributed, so that the center of gravity G2' of the bed moves further toward the left tire grounding line T2. Nor.

Therefore, in a scene where earth and sand are to be unloaded with a dump trailer while traveling forward at low speed, even if the chassis frame 1 inclines to the left due to the unevenness of the road surface, the center of gravity G2 of the loading platform exceeds the left tire contact line T2. is avoided, the dump trailer T is prevented from overturning around the left tire grounding point P2.

As described above, in the dump trailer T center-of-gravity position control device, the following effects can be obtained.

(1) A truck (dump trailer T) in which a loading platform 3 is mounted on a chassis frame 1 on which tires 2 are suspended,
an equalizer mechanism (a front equalizer mechanism 6 and a rear equalizer mechanism 7) which is interposed between the chassis frame 1 and the cargo bed 3 and axially supports the cargo bed 3 so as to be swingable in the lateral direction of the vehicle with respect to the chassis frame 1;
Actuators (hydraulic cylinders 64, 65, 74, 75) provided in the equalizer mechanisms 6, 7 for changing and driving the left and right vehicle width direction inclination angles of the loading platform 3 based on external control commands;
frame tilt angle sensors 13 and 14 for detecting the frame tilt angle at which the chassis frame 1 is tilted with respect to the horizontal plane;
When the tilt angle control of the bed 3 is started, the frame tilt angle sensor values input from the frame tilt angle sensors 13 and 14 at regular time intervals are used as a reference, and the center of gravity G of the bed follows changes in the frame tilt angle sensor values. a controller 10 for outputting to the actuator an active control command for obtaining a target bed tilt angle toward the center position of the right-and-left tire ground clearance W;
Prepare.
Therefore, in a scene where the frame tilt angle changes, effective rollover prevention can be achieved by performing active control that moves the center of gravity G of the loading platform with good response to changes in the frame tilt angle.

(2) The controller 10 determines that the tilt direction is opposite to the frame tilt angle sensor values input from the frame tilt angle sensors 13 and 14 at regular time intervals, and that the tilt angle absolute value of the frame tilt angle sensor value is is calculated as the target bed tilt angle value (S5 in FIG. 8).
That is, the direction of the target bed tilt angle is opposite to the frame tilt direction, and the angle of the target bed tilt angle is the same as the absolute value of the frame tilt angle. The horizontal position of Therefore, in the bed tilt angle control that targets the horizontal position of the bed 3, even if the frame tilt angle changes to the left or right, the center of gravity G of the bed will follow this change and move toward the central position of the left and right tire grounding distance W. Become. Therefore, even when the vehicle is traveling on an uneven road surface in which the frame inclination angle changes from side to side, the cargo bed 3 can be maintained in a horizontal position regardless of the lateral swing of the chassis frame 1 .

(3) The hydraulic source includes an oil pump 93 and an accumulator 96, and a plurality of types of flow control valves (first flow control valves 100b, 101b , second flow control valves 100c, 101c, third flow control valves 100d, 101d) (hydraulic unit for hydraulic cylinder 9),
The actuator is a pair of left and right hydraulic cylinders (hydraulic cylinders 64, 65, 74, 75) that expand and contract by pressurized hydraulic oil supplied from a flow control valve in the hydraulic unit,
The controller 10 calculates the equalizer movement angle (EQ movement angle) based on the target bed inclination angle, and among the plurality of types of flow control valves, when the equalizer movement angle is greater than a predetermined angle, the valve operation speed is high. Select the control valve (third flow control valve 100d, 101d), select the flow control valve (first flow control valve 100b, 101b) whose valve operation speed is lower as the equalizer movement angle is smaller, and for the selected valve to output an active control command (S5 to S12 in FIG. 8).
For example, when only a flow control valve with a medium valve operating speed is used, the equalizer movement response is delayed when the equalizer movement angle per unit time (the control amount of the bed tilt angle) is large. On the other hand, when the equalizer movement angle per unit time is small, the equalizer movement response speed becomes excessive, causing fluctuations in the loading platform 3 . On the other hand, by preparing multiple types of flow control valves with different valve operating speeds and selecting a flow control valve with an appropriate valve operating speed according to the equalizer movement angle, it is possible to prevent a response delay in moving the equalizer and It is possible to achieve both the prevention of fluctuations in the

(4) Equipped with bed tilt angle sensors 15 and 16 for detecting the bed tilt angle at which the bed 3 is tilted with respect to the horizontal plane,
The controller 10 monitors the bed tilt angle sensor values from the bed tilt angle sensors 15 and 16 during the tilt angle control of the bed 3 (S13 in FIG. 8), and if the bed tilt angle sensor value is equal to or less than the abnormality determination threshold, the bed 3 is continued (S13→S14→S3 in FIG. 8), and when the value of the bed tilt angle sensor exceeds the abnormality determination threshold, the tilt angle control of the bed 3 is stopped and the process shifts to fail-safe processing (FIG. 8). S13→S17→S18).
That is, since the tilt angle control of the loading platform 3 is a control for obtaining loading platform balancing operation in which the loading platform posture is kept horizontal regardless of the swinging of the chassis frame 1, the control can be performed by monitoring the loading platform inclination angle. Normal/abnormal can be determined. Therefore, if it is determined that the tilt angle control of the bed 3 is abnormal while the control is being executed to maintain the horizontal posture of the bed 3 regardless of the swing of the chassis frame 1, the tilt angle control of the bed 3 is stopped. It is possible to transition to fail-safe processing.

(5) The truck is a dump truck ( dump trailer T),
As an equalizer mechanism, a front equalizer mechanism 6 interposed between the front portion of the chassis frame 1 and the lower end side of the dump cylinder 5, and an equalizer mechanism 6 interposed between the rear portion of the chassis frame 1 and the rear portion of the loading platform 3, and a dump spindle. S and a rear equalizer mechanism 7 provided at a position coinciding with the longitudinal direction of the vehicle (Fig. 1).
Therefore, in a scene where a dump truck (dump trailer T) moves forward at low speed while unloading earth and sand while raising the loading platform 3, automatic control of the loading platform inclination angle can reduce the unevenness of the road surface at the work site. It is possible to prevent a rollover that is likely to occur in some cases.

(6) When the dump cylinder 5 detects that the front end of the loading platform 3 has risen by a first predetermined value (first dumping angle) or more, the controller 10 starts tilt angle control of the loading platform 3 (see S1 in FIG. 8 → S2→S3), when the dump cylinder 5 detects that the front end of the loading platform 3 has descended below a second predetermined value (second dumping angle), the tilt angle control of the loading platform 3 is terminated, and the frame tilt angle and the loading platform tilt angle are adjusted. The storage operation control of the loading platform 3 is started to set the deviation angle to zero degrees (S14→S15 in FIG. 8).
That is, when controlling the tilt angle of the loading platform 3, a space is required between the chassis frame 1 and the loading platform 3 to allow the loading platform to tilt. Further, when returning from tilt angle control of the loading platform 3 , it is necessary to return the loading platform 3 to the parallel arrangement with respect to the chassis frame 1 . Therefore, by using the dump condition as the start condition and the end condition of the tilt angle control of the bed 3, the tilt angle of the bed 3 can be controlled even though it is a dump truck (dump trailer T). In addition, by starting the retraction control that is performed simultaneously with the end of the tilt angle control of the cargo bed 3, the cargo bed 3 can be returned to the parallel arrangement with respect to the chassis frame 1 without requiring manual operation.

The truck bed center-of-gravity position control system of the present invention has been described above based on the first embodiment, but the specific configuration is not limited to this first embodiment, and can be set forth in each claim of the scope of claims. Design changes, additions, etc. are permitted as long as they do not deviate from the gist of the invention.

In the first embodiment, the hydraulic cylinders 64, 65, 74, and 75 are used as actuators for changing the tilt angle of the cargo bed 3 in the lateral direction based on an external control command. However, the actuator is not limited to the hydraulic cylinder, as long as it can change and drive the tilt angle of the cargo bed in the left and right vehicle width direction, such as an electric motor, a hydraulic motor, or a pneumatic cylinder.

In the first embodiment, an example is shown in which an air cylinder provided on the back surface of the rear end side of the cargo bed 3 is used as the tailgate actuator for locking and unlocking the tailgate 4 . However, the tailgate actuator is not limited to an air cylinder, as long as it can lock and unlock the tailgate, such as a hydraulic cylinder or an electric motor.

Embodiment 1 shows an example in which the front proximity sensor 11 is provided as means for detecting the rise of the front end of the cargo bed 3 and the rear proximity sensor 12 is provided as means for detecting the lowering of the front end of the cargo bed 3 . However, as a means for detecting the front end rise/drop of the loading platform, there is a means such as an optical sensor or a sound wave sensor that detects the front end rising/lowering of the loading platform by measuring the distance from the chassis frame. good, and not limited to proximity sensors.

Embodiment 1 shows an example in which only the lateral vehicle width direction inclination angle of the loading platform 3 is controlled. However, it is also possible to add an actuator for changing the tilt angle of the loading platform in the longitudinal direction of the vehicle and control both the tilt angle of the loading platform in the lateral direction of the vehicle and the tilt angle of the loading platform in the longitudinal direction of the vehicle.

Embodiment 1 shows an example in which three types of flow control valves, ie, low speed, medium speed, and high speed, are prepared as a plurality of types of flow control valves having different valve operating speeds. However, as a plurality of types of flow control valves with different valve operating speeds, two types of flow control valves, low speed and high speed, may be prepared, or four or more types of flow control valves may be prepared. good.

Embodiment 1 shows an example in which the truck bed center-of-gravity position control system of the present invention is applied to a dump trailer T which is a tractor and trailer vehicle. However, the truck bed center-of-gravity position control device of the present invention can also be applied to general dump trucks for transporting gravel, etc., and can of course be applied to trucks that do not have a bed dumping function. can be applied. In addition, when applying to a truck that does not have a dumping function of the cargo bed, in the mounting structure of the chassis frame and cargo bed, secure a space between the chassis frame and the cargo bed to allow the inclination of the cargo bed. It is necessary to leave

1 chassis frame 2 tire 3 loading platform 4 tailgate 5 dump cylinder 6 front equalizer mechanism (equalizer mechanism)
62 Front equalizer shaft 64, 65 Hydraulic cylinder (actuator)
7 Rear equalizer mechanism (equalizer mechanism)
72 Rear equalizer shaft 74, 75 Hydraulic cylinder (actuator)
8 dump cylinder hydraulic unit 9 hydraulic unit for hydraulic cylinder 93 oil pump 96 accumulator 10 controller 11 front proximity sensor 12 rear proximity sensor 13 front frame tilt angle sensor (frame tilt angle sensor)
14 rear frame tilt angle sensor (frame tilt angle sensor)
15 Front bed tilt angle sensor (load bed tilt angle sensor)
16 rear bed tilt angle sensor (load bed tilt angle sensor)
100 Front control valve unit 100a Direction control valve 100b First flow control valve 100c Second flow control valve 100d Third flow control valve 101 Rear control valve unit 101a Direction control valve 101b First flow control valve 101c Second flow control valve 101d 3 Flow rate control valve S Dump shaft G Center of gravity W Ground clearance between left and right tires

Claims (4)

A truck in which a bed is mounted on a chassis frame on which tires are suspended,
an equalizer mechanism that is interposed between the chassis frame and the cargo bed and axially supports the cargo bed so as to be swingable in the lateral direction of the vehicle with respect to the chassis frame;
an actuator provided in the equalizer mechanism for changing and driving the left-right vehicle width direction inclination angle of the loading platform based on an external control command;
a frame tilt angle sensor for detecting a frame tilt angle at which the chassis frame is tilted with respect to a horizontal plane;
When the tilt angle control of the loading platform is started, the center of gravity of the loading platform shifts to the left and right tires based on the frame inclination angle sensor value input from the frame inclination angle sensor at regular time intervals as a reference, following the change in the frame inclination angle sensor value. a controller that outputs an active control command to the actuator to obtain a target bed tilt angle toward the center position of the ground clearance;
A hydraulic unit having an oil pump and an accumulator as a hydraulic source, and having a plurality of types of flow control valves with different valve operating speeds when controlling the flow rate of the pressurized hydraulic oil from the accumulator ,
The actuator is a pair of left and right hydraulic cylinders that expand and contract by pressurized hydraulic oil supplied from the flow control valve provided in the hydraulic unit,
The controller sets the tilt direction to be opposite to the frame tilt angle sensor value input from the frame tilt angle sensor at regular time intervals, and the tilt angle absolute value of the frame tilt angle sensor value is the same. , calculated as the cargo bed inclination angle target value,
calculating an equalizer movement angle based on the target bed tilt angle, and selecting a flow control valve with a high valve operating speed from among the plurality of types of flow control valves when the equalizer movement angle is greater than a predetermined angle; A bed center-of-gravity position control device for a truck, wherein a flow rate control valve having a lower valve operating speed is selected as the equalizer movement angle is smaller, and an active control command is output to the selected valve. In the truck center-of-gravity position control device according to claim 1 ,
a bed tilt angle sensor that detects a bed tilt angle at which the bed is tilted with respect to a horizontal plane;
The controller monitors the bed tilt angle sensor value from the bed tilt angle sensor during the bed tilt angle control, and continues the bed tilt angle control if the bed tilt angle sensor value is equal to or less than an abnormality determination threshold. and, when the value of the bed tilt angle sensor exceeds an abnormality determination threshold value, the bed tilt angle control is stopped and a fail-safe process is started. In the truck bed center-of-gravity position control device according to claim 1 or 2 ,
The truck is a dump truck capable of moving up and down the front end of the loading platform about a dump spindle set at the rear of the loading platform by a dump cylinder whose upper end side is supported by the front end of the loading platform,
The equalizer mechanism includes a front equalizer mechanism interposed between the front portion of the chassis frame and the lower end side of the dump cylinder, a rear equalizer mechanism interposed between the rear portion of the chassis frame and the rear portion of the cargo bed, and the dump support. A center-of-gravity position control device for a truck, comprising: a rear equalizer mechanism provided at a position coinciding with the axis and the longitudinal direction of the vehicle. In the truck bed center-of-gravity position control device according to claim 3 ,
When the dump cylinder detects that the front end of the cargo bed has risen by a first predetermined value or more, the controller starts tilt angle control of the cargo bed, and causes the dump cylinder to tilt the front end of the cargo bed to a second predetermined value or less. When the lowering of the truck is detected, the tilt angle control of the bed is finished, and the retraction operation control of the bed is started to set the deviation angle between the frame inclination angle and the bed inclination angle to zero degrees. Center of gravity position control device.

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