JP2023031047A - Cargo bed descending system and trolley - Google Patents

Abstract

To provide a cargo bed descending system capable of preferably descending a cargo bed during travel, and a trolley.SOLUTION: A cargo bed descending system includes a cargo bed attached to a trolley, a raising device that raises the cargo bed, and a pressure sensor that measures a pressure generated in the rasing device. Descending operation of the cargo bed is automatically performed with a fact, as a necessary condition, that the cargo bed floats in the pressure sensor and a pressure value corresponding to a specific travel state in which a certain vibration or more is input to the cargo bed is detected.SELECTED DRAWING: Figure 5

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transport vehicle equipped with a loading platform, and relates to a system for automatically lowering the loading platform during travel, and a transport vehicle equipped with the system.

A transport vehicle used at a construction site or the like has a loading platform on the vehicle body, and a load such as earth and sand loaded on the loading platform is discharged by tilting the loading platform (in addition, transportation such as a dump truck Regarding a vehicle, the operation of tilting the loading platform to discharge the loaded earth and sand is generally referred to as "discharging", but in this specification, in view of the fact that the cargo of the truck is not necessarily earth and sand, the operation of discharging the cargo is referred to. shall be referred to as “discharge”). Here, when the bed is raised for unloading, the load of the bed and the load is supported by the fulcrum of the lifting motion of the bed on the frame of the vehicle body and the hoisting device of the bed. When the transport vehicle is driven in this state, stress is concentrated on the parts that support the load of the loading platform and the cargo (pins and hoisting devices provided at the fulcrum of the loading platform) due to the acceleration due to the vibration, resulting in shortening of the service life, etc. There is a risk of connection. Therefore, when running the transport vehicle, it is a general rule to lower the loading platform so that it is in contact with the frame.

For example, Patent Documents 1 and 2 listed below are documents showing the general technical level of such vehicles.

JP 2017-193261 A JP-A-2002-46657

However, after unloading the cargo, the operator forgot to lower the cargo bed and started traveling, or the operator lowered the cargo bed insufficiently and started traveling with the cargo bed slightly raised. can occur. In order to prevent such a situation, for example, it is conceivable to introduce a mechanism for locking the operation of the loading platform and forcibly lowering the loading platform on the condition that the traveling operation is input to the vehicle. However, at a construction site, for example, there are cases where a vehicle is gently run with the loading platform tilted to spread earth and sand over a certain range (even if the vehicle is traveling at a sufficiently low speed, For example, there is no need to worry about excessive loads being applied to the fulcrum of the bed and the hoisting device even when the bed is raised. There is a risk that it will occur. Therefore, there has been a demand for a mechanism that lowers the loading platform only when it is appropriate to travel.

SUMMARY OF THE INVENTION In view of such circumstances, it is an object of the present invention to provide a loading platform lowering system and a truck capable of suitably lowering the loading platform during travel.

The present invention comprises a loading platform attached to a truck, a hoisting device for hoisting the loading platform, and a pressure sensor for measuring the pressure generated in the hoisting device. On the other hand, a loading platform lowering system is configured to automatically execute the loading platform lowering operation on the condition that a pressure value corresponding to a specific running state in which a certain or more vibration can be input is detected as a necessary condition. It takes

The loading platform lowering system of the present invention includes a contact sensor for detecting contact between the loading platform and a frame forming the vehicle body of the transport vehicle, and is configured so that the floating state of the loading platform can be grasped by the contact sensor. Further, when the pressure sensor detects a pressure value corresponding to a specific running state more than a set number of times during the continuation of the floating state of the cargo bed, the cargo bed lowering operation is automatically performed. be able to.

Further, the present invention relates to a truck characterized by being equipped with the platform lowering system described above.

ADVANTAGE OF THE INVENTION According to the loading platform lowering system and the truck of the present invention, it is possible to obtain an excellent effect of suitably lowering the loading platform during traveling.

It is a side view which shows an example of the form of the truck to which this invention is applied. 1 is a block diagram showing an example of the configuration of a platform lowering system according to an embodiment of the present invention; FIG. FIG. 4 is an explanatory diagram showing the outline of the distribution of the load and the reaction force in the truck with the platform lowered. FIG. 4 is an explanatory diagram showing an outline of the distribution of load and reaction force in a transport vehicle with a floating platform; 4 is a flow chart showing an example of a measurement procedure in a method for measuring the number of times of unloading according to the implementation of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an example of a truck equipped with a platform lowering system according to the implementation of the present invention, and FIG. 2 shows an example of the configuration of the platform lowering system. As shown in FIG. 1, the transport vehicle 1 is provided with a loading platform 3 attached to the rear portion of a vehicle body 2 and configured to load a load C such as earth and sand, and crawlers 4 as traveling devices attached on both left and right sides. there is

Between the upper surface of the frame 5 forming the vehicle body 2 and the lower surface of the bed 3, a fluid pressure cylinder 6 is provided as a hoisting device for raising and lowering the bed 3. As shown in FIG. The fluid pressure cylinder 6 is rotatably attached to the upper surface of the frame 5 at its base end and to the lower surface of the bed 3 at its tip. 3 is raised and lowered with respect to the vehicle body 2.

A contact sensor 7 for detecting contact between the loading platform 3 and the frame 5 is attached between the upper surface of the frame 5 and the loading platform 3 . In this embodiment, the mounting position of the contact sensor 7 is forward of the mounting position of the fluid pressure cylinder 6 on the upper surface of the frame 5 . Here, a physical contact type switch is assumed as the contact sensor 7, but the configuration of the contact sensor 7 is not limited to this, and any sensor capable of detecting contact between the frame 5 and the loading platform 3 can be used. Any device may be used. For example, an optical sensor or the like can be used.

The expansion and contraction of the fluid pressure cylinder 6 is controlled by the control device 9 via the fluid pressure device 8 (see FIG. 2). The control device 9 is an information processing device that monitors and controls the operational states of the equipment of each part that constitutes the truck 1 (see FIG. 1). The fluid pressure device 8 inputs fluid pressure to the extension side (bottom side) of the fluid pressure cylinder 6 according to a command signal input from the control device 9 . The fluid pressure cylinder 6 expands and contracts by this fluid pressure and supports the weight of the loading platform 3 .

A pressure sensor 10 is attached in the middle of the circuit for inputting the fluid pressure from the fluid pressure device 8 to the fluid pressure cylinder 6, which supports the weight of the loading platform 3 and senses the pressure generated in the fluid pressure cylinder 6 when performing the hoisting motion. It is designed to measure.

A display device 11 (see FIG. 2; not shown in FIG. 1) is provided in the driver's seat of the truck 1 (see FIG. 1). The display device 11 is a display that displays various visual information according to image signals input from the control device 9. For example, the display device 11 displays the operating state of the loading platform 3, the pressure value detected by the pressure sensor 10, and the like. It is possible to do so.

Further, the driver's seat of the transport vehicle 1 is provided with an operation device 13 for inputting an operation command to the control device 9 . The operation device 13 is a device for manipulating the driving of the transport vehicle 1, and can input operations related to operations such as traveling by the crawler 4 and raising and lowering the loading platform 3 by the fluid pressure cylinder 6, for example.

In the transport vehicle 1 of this embodiment equipped with such a system, the contact sensor 7 detects the floating state of the loading platform 3 (whether or not it is floating with respect to the frame 5), and the vibration generated during travel is suppressed. Monitoring is performed by the sensor 10, and when the pressure sensor 10 detects a pressure value equal to or higher than a certain threshold value as a necessary condition, the loading platform 3 is automatically lowered. Further, in this embodiment, while the loading platform 3 continues to float, the number of times the pressure sensor 10 detects a pressure value equal to or greater than the threshold value is counted. is running.

FIG. 3 shows the distribution of the load when the loading platform 3 is lowered and the distribution of the reaction force generated in various parts of the vehicle (the distribution of the load and the reaction force shown here is for the sake of simple explanation). It is a rough outline, not necessarily accurate down to the details, and does not show all the loads and reaction forces that occur in the actual vehicle (the same applies to the following FIG. 4). When the cargo bed 3 is lowered, the bottom surface of the cargo bed 3 is in surface contact with the crossties provided on the upper surface of the frame 5, and the load of the cargo bed 3 and the cargo C (indicated by the black arrow in the figure) is and the contact surface of the frame 5 and the pin provided at the fulcrum of the undulation of the loading platform 3 on the frame 5 . That is, the reaction force against the load is widely distributed as indicated by the white arrows in the drawing, and the load of the loading platform 3 and cargo C is supported by this. The reaction force against the load is not concentrated on one specific point. Also, when the vehicle is running, due to the acceleration accompanying the vibrations, a load greater than the static weight of the loading platform 3 and cargo C is applied to various locations. Since the heavy load is distributed to the frame 5, it does not become an excessive load on the structural members in various places.

On the other hand, FIG. 4 shows the distribution of the load when the cargo bed 3 is floating and the distribution of the reaction force generated in various parts of the vehicle. When the cargo bed 3 is floating, the load of the cargo bed 3 and the load C is not distributed over the upper surface of the frame 5 and is supported by the fulcrum pin of the cargo bed 3 and the hydraulic cylinder 6 . Here, when the vehicle is stationary or when the vehicle is traveling at a sufficiently low speed, this state is assumed as normal unloading work, and the fulcrum of the loading platform 3 and the fluid There is no concern that the pressure cylinder 6 will be overstressed. However, when the vehicle travels at a speed above a certain level while the cargo bed 3 is in a floating state, the acceleration due to the generated vibration causes, in addition to the vertical load, for example, a horizontal load shown in black in FIG. As indicated by arrows, a large load is applied to the fulcrum of the loading platform 3 and both ends of the fluid pressure cylinder 6 . As a reaction force against this, a large stress is generated at the fulcrum of the loading platform 3 and both ends of the fluid pressure cylinder 6 as indicated by the white arrows, which may impose an excessive load on the constituent members at various locations.

Therefore, in this embodiment, in order to prevent such a situation, in addition to the presence or absence of input to the contact sensor 7, the control device 9 grasps the state of the loading platform 3 and the running state of the vehicle through the measurement value of the pressure sensor 10, When it is determined that the cargo bed 3 is in a floating state and that the vehicle is in a running state in which a certain or more vibration can be input to the cargo bed 3, the cargo bed 3 is automatically lowered. there is That is, as described above, the pressure sensor 10 monitors the vibrations that occur as the vehicle travels, and on the condition that the pressure value above a certain threshold value is detected a certain number of times or more, the loading platform 3 is automatically lowered. It's like

The procedure for lowering the loading platform 3 can be summarized in a flow chart as shown in FIG. 5, for example.

The control device 9 waits while determining whether or not the contact of the loading platform 3 is input to the contact sensor 7 (step S1). The contact sensor 7 is on when the loading platform 3 is lowered. When the input to the contact sensor 7 is ON, the process proceeds to step S2, sets the count value of the counter to zero, and returns to step S1 again. Here, the counter is a counter for determining whether or not it is necessary to lower the loading platform 3 based on the measured value of the pressure sensor 10. As will be described later, when the measured value of the pressure sensor 10 exceeds a certain threshold value, is counted up each time is recorded, and the operation of lowering the loading platform 3 is executed on the condition that the count reaches a set number of times or more.

When the loading platform 3 is in a floating state, it is determined in step S1 that the input to the contact sensor 7 is off. In this case, the controller 9 proceeds to step S3.

In step S<b>3 , it is determined whether or not a vehicle running operation is input to the operating device 13 . If the travel operation is not input here, the process directly returns to step S1.

If there is an input of the running operation, the process proceeds to step S4, and the measurement value of the pressure sensor 10 is further determined. Here, the measured value of the pressure sensor 10 is compared with a preset threshold. At step S5, the count of the counter is incremented by 1, and the process proceeds to step S6.

In step S6, it is determined whether or not the current count value of the counter is equal to or greater than the set number of times. If it is less than the set number of times, the process returns to step S1.

Here, the threshold used as a criterion for determination in step S4 is that when the loading platform 3 is lifted from the frame 5 and vibrations of a certain level or more are input to the loading platform 3, the pressure beyond that is reflected in the fluid pressure cylinder 6. It is the value assumed to occur as a force. For example, when the vehicle travels on uneven ground at a certain speed or more, or when the vehicle climbs over a large step even at a low speed, if the cargo bed 3 is floating, the cargo bed 3 may be suspended above a certain level. , and a reaction force corresponding to this vibration is generated in the fluid pressure cylinder 6 . Therefore, if an appropriate threshold value is set for the pressure value generated in the fluid pressure cylinder 6, when a pressure value equal to or higher than this threshold value is detected, the vehicle is in a running state in which a certain level or more of vibration is input to the cargo bed 3. (This state is hereinafter referred to as a "specific running state" for convenience), and if the pressure value is less than the threshold value, it can be considered that the vehicle is not in the specific running state. Here, the threshold used as the basis for the determination is that, when the cargo bed 3 in the floating state is subjected to vibrations corresponding to or more than that value, the configuration of the cargo bed 3, the frame 5, the fluid pressure cylinder 6, etc. An appropriate value may be set as a pressure value that can cause a load exceeding the allowable value on the member.

Here, if it is determined that the vehicle is in the specific driving state only once the pressure value corresponding to the specific driving state (that is, the pressure value equal to or greater than the threshold value) is detected, there is a concern that overdetection may occur. This is because, even if the vehicle is not in the specific running state, there is a possibility that the pressure value will rise temporarily due to, for example, some vibration being input from the outside. Therefore, in this embodiment, after the loading platform 3 is lifted from the frame 5 (that is, after it is confirmed that the contact sensor 7 is turned off in step S1), the number of times a pressure value equal to or greater than the threshold value is detected is counted (step S5 ), and when this number of times exceeds the set number of times, the process proceeds to the next step S7 (lowering operation of the loading platform 3) for the first time. By doing so, it is possible to reduce the possibility of forcibly lowering the loading platform 3 due to erroneous detection. The set number of times used as a criterion for determination in step S6 can be appropriately set to 2 times, 3 times, or the like, as the number of times that can reliably determine that the vehicle body is in the specific running state.

In step S6, if the count value of the counter is equal to or greater than the set number of times, it means that the cargo bed 3 has been floating since it was determined in the previous step S1 that the cargo bed 3 is floating. , means that a pressure value equal to or higher than the threshold corresponding to the specific running state has been detected in the fluid pressure cylinder 6 more than a set number of times. Therefore, the control device 9 inputs contraction control to the fluid pressure cylinder 6 to lower the loading platform 3 (step S7).

While the loading platform 3 is being lowered, the control device 9 determines whether or not there is a contact input to the contact sensor 7 (step S8). When the input to the contact sensor 7 is OFF, the lowering operation of the loading platform 3 is continued (step S7). At the stage when the input to the contact sensor 7 is turned on, it can be determined that the loading platform 3 has been completely lowered. At step S9, the count of the counter is reset to zero. After that, the process returns to step S1 and waits while monitoring the contact sensor 7 .

In the system as described above, the loading platform 3 is automatically lowered only when it can be determined that the vehicle is in a specific running state. That is, it is not required that the vehicle is in a running state as a condition for executing the lowering operation of the cargo bed 3, but that the fluid pressure cylinder 6 is in a state in which the cargo bed 3 floats and a certain level of vibration or more can be input to the cargo bed 3. Since the operation of lowering the loading platform 3 is performed only when it can be judged through the pressure value, it is possible to operate the vehicle, for example, to unload the vehicle while traveling at a low speed. In this way, by forcibly lowering the loading platform 3 only when necessary, it is possible to prevent the continuation of traveling in a specific traveling state without disturbing the work of the truck 1, and to It is possible to prevent an excessive load from occurring on the Moreover, by providing such a system in the truck 1, the required strength of the frame 5 and the fluid pressure cylinders 6 can be suppressed, the reinforcing structure can be simplified, and the manufacturing cost can be reduced.

As described above, the loading platform lowering system of this embodiment includes the loading platform 3 attached to the truck 1, the hoisting device (fluid pressure cylinder) 6 for raising and lowering the loading platform 3, and the pressure The pressure sensor 10 detects a pressure value corresponding to a specific traveling state in which the cargo bed 3 is lifted and a certain level or more of vibration is input to the cargo bed 3, and the cargo bed 3 is lowered. Configured to perform actions automatically. In this way, by forcibly lowering the loading platform 3 only when necessary, it is possible to prevent the continuation of traveling in a specific traveling state without interfering with the work of the truck 1, thereby preventing the truck 1 from traveling. It is possible to prevent excessive load from being applied to constituent members at various locations.

In addition, the loading platform lowering system of this embodiment includes a contact sensor 7 for detecting contact between the loading platform 3 and the frame 5 forming the vehicle body 2 of the truck 1, and the contact sensor 7 can grasp the floating state of the loading platform 3. In addition, when the pressure sensor 10 detects a pressure value corresponding to a specific traveling state more than a set number of times while the cargo bed 3 is in a floating state, the cargo bed 3 is lowered. is configured to run automatically. By doing so, it is possible to reduce the possibility that the cargo bed 3 is forcibly lowered due to an erroneous detection.

Further, since the truck 1 of the present embodiment is provided with the above-described platform lowering system, it is possible to achieve the same effects as described above.

Therefore, according to the present embodiment, the loading platform can be preferably lowered during traveling.

It should be noted that the platform lowering system and the transport vehicle of the present invention are not limited to the above-described embodiments, and of course various modifications can be made without departing from the gist of the present invention.

REFERENCE SIGNS LIST 1 transport vehicle 2 vehicle body 3 carrier 5 frame 6 hoisting device (fluid pressure cylinder)
7 contact sensor 10 pressure sensor

Claims (3)

a carrier attached to the carrier;
a hoisting device for hoisting the loading platform;
A pressure sensor that measures the pressure generated in the hoisting device,
A necessary condition is that the pressure sensor detects a pressure value corresponding to a specific running state in which the loading platform floats and vibrations of a certain level or more can be input to the loading platform,
A loading platform lowering system configured to automatically lower the loading platform. A contact sensor for detecting contact between the loading platform and a frame forming the vehicle body of the truck is provided, and the contact sensor is configured to be able to grasp the floating state of the loading platform,
A further necessary condition is that the pressure sensor detects a pressure value corresponding to a specific traveling state more than a set number of times while the cargo bed is in a floating state,
The loading platform lowering system according to claim 1, wherein the loading platform lowering operation is configured to be performed automatically. A transport vehicle comprising the platform lowering system according to claim 1 or 2.

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