Bed lowering system and transport vehicle

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

[Technical Field]

[0001] The present invention relates to a system for automatically lowering a loading platform in a transport vehicle equipped with a loading platform while the vehicle is traveling, and to a transport vehicle equipped with the system. [Background technology]

[0002] Trucks used at construction sites and other locations have a loading platform on their body, and the platform is tilted to unload soil and other loads. (Note: For trucks like dump trucks, the action of tilting the platform to unload loaded soil is generally referred to as "unloading," but in this specification, the action of unloading the load will be referred to as "unloading" since the load on trucks is not necessarily soil and sand.) When the platform is raised for unloading, the weight of the platform and the load is supported by the platform's lifting and lowering fulcrum on the vehicle frame and the platform's lifting and lowering device. If the truck is driven in this state, acceleration due to vibration can cause stress to concentrate on the parts supporting the platform and the load (the pins and lifting and lowering device attached to the platform's fulcrum), potentially shortening their lifespan. Therefore, when driving a truck, the platform should generally be lowered so that it is in contact with the frame.

[0003] Incidentally, documents showing the general state of the art regarding such transport vehicles include, for example, Patent Documents 1 and 2 listed below. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-193261 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-46657 Summary of the Invention [Problem to be solved by the invention]

[0005] However, after unloading, situations can occur where the operator forgets to lower the loading platform before starting travel, or where the operator lowers the loading platform but insufficiently, causing the loading platform to slightly rise. To prevent such situations, a mechanism could be introduced that locks the loading platform operation and forcibly lowers the loading platform when a driving command is input to the vehicle. However, at construction sites, for example, a vehicle may be gently driven with the loading platform tilted to spread soil over a certain area (note that if the vehicle is traveling at a sufficiently slow speed, there is no risk of excessive load being placed on the platform's support or hoisting device, even when the loading platform is raised). Therefore, preventing the loading platform from being tilted could hinder transportation operations. Therefore, a mechanism that lowers the loading platform while traveling only when appropriate has been developed.

[0006] SUMMARY OF THE INVENTION In view of the above circumstances, the present invention aims to provide a platform lowering system and a transport vehicle that can appropriately lower the platform while the transport vehicle is traveling. [Means for solving the problem]

[0007] The present invention includes a carrier attached to a transport vehicle; Raise and lower the loading platform Fluid pressure cylinder A lifting device; a pressure sensor for measuring the pressure generated in the elevation device; a contact sensor that detects contact with a frame that forms the body of the transport vehicle; Equipped with The contact sensor is configured to detect the floating state of the loading platform, In the pressure sensor, While the floating state continues A pressure value corresponding to a specific driving state in which a certain level of vibration or more can be input to the loading platform is More than the set number of times As a prerequisite for detection, The set number of times is set so that the loading platform lowering operation is not performed even if the transporter vehicle is not in a specific driving state and other vibrations are input from the outside, causing a temporary increase in pressure value. , Under the condition that the load of the loading platform and the load of the cargo act, the load on the loading platform support point and the fluid pressure cylinder due to the acceleration caused by the vibration of a certain level or more can be handled. The lowering operation of the loading platform is automatically performed. This relates to a loading platform lowering system characterized by the above.

[0009] The present invention also relates to a transport vehicle equipped with the above-described platform lowering system. [Effects of the Invention]

[0010] The bed lowering system and transporter of the present invention can provide the excellent effect of lowering the bed appropriately while traveling. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a side view showing an example of a form of a transporter to which the present invention is applied. [Figure 2] 1 is a block diagram showing an example of the configuration of a loading platform lowering system according to an embodiment of the present invention; [Figure 3] FIG. 10 is an explanatory diagram showing an outline of the distribution of load and reaction force in a transporter with the loading platform lowered. [Figure 4] FIG. 10 is an explanatory diagram showing an outline of the distribution of load and reaction force in a transporter with a floating platform. [Figure 5] 1 is a flowchart showing an example of a measurement procedure in a method for measuring the number of unloadings according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0013] Fig. 1 shows an example of a transport vehicle equipped with a bed lowering system according to the present invention, and Fig. 2 shows an example of the configuration of the bed lowering system. As shown in Fig. 1, the transport vehicle 1 has a bed 3 attached to the rear of a vehicle body 2 and configured to carry a load C such as earth and sand, and crawlers 4 attached to both the left and right sides as traveling devices.

[0014] A fluid pressure cylinder 6 is provided between the upper surface of the frame 5 that constitutes the vehicle body 2 and the underside of the loading platform 3 as a lifting device that raises and lowers the loading platform 3. The fluid pressure cylinder 6 is rotatably attached at its base end to the upper surface of the frame 5 and at its tip end to the underside of the loading platform 3, and is configured to raise and lower the loading platform 3 relative to the vehicle body 2 by expanding and contracting between the frame 5 and the loading platform 3.

[0015] Furthermore, a contact sensor 7 that detects 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 attachment position of the contact sensor 7 is forward of the installation position of the fluid pressure cylinder 6 on the upper surface of the frame 5. Note that, although a physical contact type switch is assumed as the contact sensor 7 here, the configuration of the contact sensor 7 is not limited to this, and any device that can detect contact between the frame 5 and the loading platform 3 may be used. For example, an optical sensor or the like may also be used.

[0016] The extension and retraction of the fluid pressure cylinder 6 is controlled by a control device 9 via a fluid pressure device 8 (see Figure 2). The control device 9 is an information processing device that monitors and controls the operating status of each device that makes up the transporter 1 (see Figure 1). The fluid pressure device 8 inputs fluid pressure to the extension side (bottom side) of the fluid pressure cylinder 6 in response to a command signal input from the control device 9. The fluid pressure cylinder 6 expands and contracts due to this fluid pressure, and also supports the weight of the loading platform 3.

[0017] A pressure sensor 10 is attached to the circuit that inputs fluid pressure from the fluid pressure device 8 to the fluid pressure cylinder 6, and is used to measure the pressure generated in the fluid pressure cylinder 6 when supporting the weight of the loading platform 3 and performing the raising and lowering operation.

[0018] The driver's seat of the transporter 1 (see FIG. 1) is provided with a display device 11 (see FIG. 2; not shown in FIG. 1). The display device 11 is a display that displays various visual information in response to image signals input from the control device 9, and is capable of displaying, for example, the operating status of the loading platform 3, the pressure value detected by the pressure sensor 10, etc.

[0019] The driver's seat of the transporter 1 is also provided with an operating device 13 for inputting operation commands to the control device 9. The operating device 13 is a device that allows a person to operate the transporter 1, and is capable of inputting operations related to operations such as running by the crawlers 4 and raising and lowering the loading platform 3 by the fluid pressure cylinder 6.

[0020] In the transporter 1 of this embodiment equipped with such a system, the floating state of the platform 3 (whether it is floating relative to the frame 5) is detected by the contact sensor 7, and vibrations that occur during travel are monitored by the pressure sensor 10, and the platform 3 is automatically lowered when the pressure sensor 10 detects a pressure value above a certain threshold. Also, in this embodiment, while the platform 3 remains floating, the pressure sensor 10 counts the number of times that it detects a pressure value above the threshold, and when this number reaches a set number or more, it is an additional necessary condition that the platform 3 is lowered.

[0021] Figure 3 shows the distribution of load when the loading platform 3 is lowered and the distribution of reaction forces generated at various points on the vehicle (note that the distribution of load and reaction forces shown here is a simple outline for the purpose of explanation, and is not necessarily accurate in every detail, nor does it depict all of the loads and reaction forces generated on an actual vehicle. The same is true for the following Figure 4). When the loading platform 3 is lowered, the underside of the loading platform 3 is in surface contact with the sleepers attached to the upper surface of the frame 5, and the load of the loading platform 3 and cargo C (indicated by the black arrows in the figure) is distributed to the contact surface between the loading platform 3 and the frame 5 and to the pins on the frame 5 that are provided as fulcrums for the ups and downs of the loading platform 3. In other words, the reaction force against the load is generated in a widely distributed manner, as indicated by the white arrows in the figure, and this supports the load of the loading platform 3 and cargo C. The reaction force against the load is not concentrated at a specific point. Furthermore, when the vehicle is running, the acceleration caused by the vibrations generated causes loads to be applied to various parts that are greater than the static weight of the loading platform 3 and cargo C. However, as long as the loading platform 3 is lowered onto the frame 5, such loads are also distributed across the frame 5, so that the loads on the various components are not excessively large.

[0022] On the other hand, Figure 4 shows the distribution of load when the loading platform 3 is floating and the distribution of reaction forces generated at various points on the vehicle. When the loading platform 3 is floating, the load of the loading platform 3 and the load C is not distributed across the upper surface of the frame 5, but is supported by the fulcrum pin of the loading platform 3 and the fluid pressure cylinder 6. If the vehicle is stationary or traveling at a sufficiently slow speed, this state is expected to be a normal loading operation, and there is no need to worry about excessive stress being generated on the fulcrum of the loading platform 3 or the fluid pressure cylinder 6. However, if the vehicle travels at a speed above a certain level while the loading platform 3 is floating in this manner, acceleration due to the generated vibrations will apply large loads to the fulcrum of the loading platform 3 and both ends of the fluid pressure cylinder 6 in addition to the vertical load, as shown by the black horizontal arrows in Figure 4. As a reaction force to this, large stresses are generated at the fulcrum of the loading platform 3 and at both ends of the fluid pressure cylinder 6 as shown by the white arrows, which may result in excessive loads on the components at various locations.

[0023] Therefore, in this embodiment, to prevent such a situation, the control device 9 grasps the state of the loading platform 3 and the traveling state of the vehicle through the measured value of the pressure sensor 10 in addition to the presence or absence of input to the contact sensor 7, and automatically lowers the loading platform 3 when it is determined that the loading platform 3 is floating and the vehicle is traveling in a manner that may cause vibrations of a certain level or more to be input to the loading platform 3. That is, as described above, the pressure sensor 10 monitors vibrations that occur during traveling, and automatically lowers the loading platform 3 when a pressure value of a certain threshold or more is detected a certain number of times or more.

[0024] The procedure for lowering the loading platform 3 can be summarized in a flowchart such as that shown in FIG.

[0025] The control device 9 waits while determining whether or not contact of the loading platform 3 has been input to the contact sensor 7 (step S1). When the loading platform 3 is lowered, the contact sensor 7 is on. If the input to the contact sensor 7 is on, the process proceeds to step S2, the count value of the counter is set to zero, and the process returns to step S1. Here, the counter is a counter that determines whether or not it is necessary to execute the operation to lower the loading platform 3 based on the measurement value of the pressure sensor 10, and as will be described later, it counts up each time the measurement value of the pressure sensor 10 records a certain threshold value or more, and the operation to lower the loading platform 3 is executed when the count reaches a set number of times or more.

[0026] If 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 control device 9 proceeds to step S3.

[0027] In step S3, it is determined whether or not a driving operation for the vehicle has been input to the operating device 13. If a driving operation has not been input, the process returns to step S1.

[0028] If a driving operation is input, the process proceeds to step S4, where a further determination is made on the measurement value of the pressure sensor 10. Here, the measurement value of the pressure sensor 10 is compared with a preset threshold value, and if it is less than the threshold value, the process returns to step S1, and if it is equal to or greater than the threshold value, the process proceeds to step S5. In step S5, the count of the counter is incremented by 1, and the process proceeds to step S6.

[0029] In step S6, it is determined whether the current count 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, and if it is equal to or greater than the set number of times, the process proceeds to step S7.

[0030] Here, the threshold value used as the criterion for judgment in step S4 is a value that is assumed to generate a pressure greater than or equal to this value as a reaction force in the fluid pressure cylinder 6 when the loading platform 3 is lifted from the frame 5 and vibrations of a certain level or greater are input to the loading platform 3. For example, when the vehicle is traveling at a certain speed or greater over uneven ground, or when the vehicle is traveling at a low speed over a large step, if the loading platform 3 is lifted, vibrations of a certain level or greater will be input to the loading platform 3, and a reaction force corresponding to this vibration will be 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 greater than this threshold is detected, it can be determined that the vehicle is in a driving state in which vibrations of a certain level or greater may be input to the loading platform 3 (hereinafter, this state will be referred to as a "specific driving state" for convenience), and when the pressure value is less than the threshold, it can be determined that the vehicle is not in the specific driving state. The threshold value used as the basis for judgment here can be set to an appropriate value as a pressure value that could cause a load greater than the allowable value to be generated on components such as the platform 3, frame 5, and fluid pressure cylinder 6 when vibrations equivalent to or greater than that value are applied to the platform 3 in a floating state.

[0031] Here, if a pressure value corresponding to the specific driving state (i.e., a pressure value equal to or greater than the threshold value) is detected only once, there is a risk of overdetection. This is because even if the vehicle is not in the specific driving state, the pressure value may temporarily increase due to, for example, some external vibration. Therefore, in this embodiment, after the loading platform 3 is lifted from the frame 5 (i.e., after the contact sensor 7 is confirmed to be off in step S1), the number of times a pressure value equal to or greater than the threshold value is detected is tallied (step S5). Only when this number of times exceeds a preset number does the system proceed to the next step S7 (lowering the loading platform 3). This reduces the possibility of the loading platform 3 being forcibly lowered due to erroneous detection. The preset number of times used as the criterion for determination in step S6 can be appropriately set, such as two or three times, as long as it is sufficient to reliably determine that the vehicle body is in the specific driving state.

[0032] 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 platform 3 has remained in a floating state since it was determined in the previous step S1 that the platform 3 was in a floating state, and that during that time, a pressure value equal to or greater than the threshold value corresponding to the specific driving state has been detected in the fluid pressure cylinder 6 a set number of times or more. Therefore, the control device 9 inputs contraction control to the fluid pressure cylinder 6, and executes the operation of lowering the platform 3 (step S7).

[0033] 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). If the input to the contact sensor 7 is OFF, the loading platform 3 continues to be lowered (step S7). When the input to the contact sensor 7 turns ON, it can be determined that the loading platform 3 has reached its final lowering position, and the loading platform 3 lowering operation is terminated and the process proceeds to step S9. In step S9, the counter is reset to zero. Thereafter, the process returns to step S1 and waits while monitoring the contact sensor 7.

[0034] The system described above automatically lowers the platform 3 only when it is determined that the vehicle is in a specific driving state. In other words, the platform 3 is lowered only when it is determined, based on the pressure value of the fluid pressure cylinder 6, that the platform 3 is floating and that a certain level of vibration may be input to the platform 3. This allows, for example, unloading of cargo while the vehicle is traveling at a low speed. By forcibly lowering the platform 3 only when necessary, it is possible to prevent the vehicle 1 from continuing to travel in a specific driving state without interfering with the work being performed by the vehicle 1 and to prevent excessive loads from being applied to the various components of the vehicle 1. Furthermore, incorporating such a system into the vehicle 1 reduces the required strength of the frame 5 and the fluid pressure cylinder 6, simplifying the reinforcement structure and reducing manufacturing costs.

[0035] As described above, the platform lowering system of this embodiment comprises the platform 3 attached to the transporter 1, the elevation device (fluid pressure cylinder) 6 that raises and lowers the platform 3, and the pressure sensor 10 that measures the pressure generated in the elevation device 6, and is configured to automatically execute the operation to lower the platform 3 when the pressure sensor 10 detects a pressure value corresponding to a specific traveling state in which the platform 3 is lifted and a certain level of vibration may be input to the platform 3. In this way, by forcibly executing the operation to lower the platform 3 only when necessary, it is possible to prevent the transporter 1 from continuing to travel in the specific traveling state without interfering with work by the transporter 1, and to prevent excessive loads from being placed on the components of the transporter 1.

[0036] The bed lowering system of this embodiment is also equipped with a contact sensor 7 that detects contact between the bed 3 and the frame 5 that forms the body 2 of the transporter 1, and is configured to be able to grasp the floating state of the bed 3 using the contact sensor 7, and is also configured to automatically lower the bed 3 when, as a necessary condition, the pressure sensor 10 detects a pressure value corresponding to a specific traveling state a set number of times or more while the bed 3 remains floating. In this way, it is possible to reduce the possibility that the bed 3 will be forcibly lowered due to a false detection.

[0037] Furthermore, the transporter 1 of this embodiment is provided with the above-mentioned platform lowering system, and therefore can achieve the same effects as those described above.

[0038] Therefore, according to the present embodiment, the loading platform can be lowered appropriately during travel.

[0039] The platform lowering system and transport vehicle of the present invention are not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0040] 1 Transport vehicle 2. Body 3 Cargo bed 5 frames 6. Lifting device (fluid pressure cylinder) 7 Contact Sensor 10 Pressure Sensor

Claims

1. A loading platform attached to a transport vehicle; a hydraulic cylinder lifting device for lifting the platform; a pressure sensor for measuring the pressure generated in the elevation device; a contact sensor for detecting contact with a frame constituting the body of the transporter; The contact sensor is configured to detect the floating state of the loading platform, The necessary condition is that the pressure sensor detects a pressure value corresponding to a specific driving state in which a certain level of vibration may be input to the loading platform a set number of times or more while the loading platform is in a floating state. The set number of times is set so that the loading platform lowering operation is not performed even if the transporter vehicle is not in a specific driving state and other vibrations are input from the outside, causing a temporary increase in the pressure value; The system is configured to automatically lower the loading platform so that it can respond to the load on the platform fulcrum and fluid pressure cylinder due to acceleration caused by vibrations of a certain level or more under conditions where the platform and cargo load are acting on the platform. A bed lowering system featuring:

2. A transport vehicle comprising the system for lowering a loading platform according to claim 1.

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