Haulage vehicle

A haulage vehicle includes a body, a load measurement device that measures a mounted load value of the body, a traveling electric motor, and a travel control device that outputs an electric motor command value, the travel control device sets a backward movement limiting set value to ON when it is determined that the haulage vehicle is in execution of either loading work or dumping work, and sets the backward movement limiting set value to OFF when a forward position signal and an accelerator pedal command value are inputted, an electric motor command value formed of a backward movement limiting command value is outputted to the traveling electric motor when the backward movement limiting set value is ON, and an electric motor command value formed of a normal command value is outputted to the traveling electric motor when the backward movement limiting set value is OFF.

TECHNICAL FIELD

The present invention relates to a haulage vehicle, and relates specifically to travel control suitable to a haulage vehicle for a mine.

BACKGROUND ART

In a mining site of a mine, a dump truck that is a kind of the haulage vehicle assumes a role of transporting dirt and ore from a loading spot to a dumping spot. In the loading spot, the haulage vehicle approaches toward an excavation bench by forward movement or backward movement, an excavation machine working at the excavation bench, and stops at the loading spot. Also, after completion of loading by the excavation machine, the haulage vehicle moves forward and moves toward a transportation road.

Further, in the dumping spot, when the dirt is mounted for example, the haulage vehicle enters a dirt reclamation area, thereafter moves backward toward and approaches the dumping spot, and stops. Then the haulage vehicle tilts a vessel of the haulage vehicle rearward and dumps the mounted dirt rearward. At this time, when the dumped dirt piles up on the ground surface and does not thoroughly drop from the vessel, the haulage vehicle moves forward while keeping the vessel to be raised, and dumps the entire load mounted within the vessel. Also, after dumping the dirt entirely, the haulage vehicle causes the vessel to fall, moves forward, and moves toward the transportation road.

That is to say, in both of the loading work and the dumping work, a work procedure of moving forward to withdraw from a working spot is common. Here, when an operator of the haulage vehicle erroneously moves the haulage vehicle backward by carelessness after the loading or dumping work, the haulage vehicle possibly collides on the excavation bench and the dumped dirt. As a result, there is a risk that the haulage vehicle is damaged.

As a technology for preventing such vehicle starting accident as described above, in Patent Literature 1, there is a description that “An in-stop travelling direction determination section determines travelling/reversing (in-stop travelling direction) when a vehicle is stopped, and an in-stop travelling direction storage section stores its result of determination. On the other hand, an in-start travelling direction determination section determines travelling/reversing (in-start travelling direction) when the vehicle is started, and compares the in-start travelling direction with the in-stop travelling direction stored in the in-stop travelling direction storage section. When both directions are matched with each other, it is determined that the in-start travelling direction is not safe. In this case, an alarm section gives an alarm to such effect, and a vehicle control section executes control of prohibiting travelling of the vehicle to prevent any accident in advance (excerption of Abstract).”

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

According to the travel control process described in Patent Literature 1, the working state of the vehicle is not recognized, and limiting control is executed using information of the moving direction immediately before stop of the vehicle and the moving direction after stop of the vehicle when the vehicle stops. Therefore, for example, when the haulage vehicle starts by travelling after the haulage vehicle stops at the loading spot by travelling, or when the haulage vehicle tries to move backward again for positional adjustment after temporary stop while approaching the loading spot or the dumping spot by backward movement, since the haulage vehicle moves in a same direction before/after stop of the vehicle, travel limiting control comes to work. Therefore, when the technology of Patent Literature 1 is applied to a haulage vehicle for a mine, deterioration of operability is worried about.

The present invention has been achieved in view of the problem described above, and its object is to provide a technology that is suitable to a haulage vehicle particularly for a mine and suppresses erroneous starting when a vehicle starts.

Solution to Problem

In order to solve the problem described above, the present invention is a haulage vehicle including a vehicle frame, a body that mounts a load, a load measurement device that measures a mounted load value of the body, a traveling electric motor, a shift lever that shifts the travel direction forward or backward, an accelerator pedal, and a travel control device that outputs an electric motor command value to the traveling electric motor, wherein the travel control device is connected to each of the load measurement device, the traveling electric motor, the shift lever, and the accelerator pedal, a backward movement limiting set value that limits backward traveling of the haulage vehicle is set to ON when it is determined that the haulage vehicle is in execution of either loading work or dumping work based on variation in a mounted load value calculated by the load measurement device, it is determined that the haulage vehicle has moved forward when a forward position signal and an accelerator pedal command value are inputted and the backward movement limiting set value is set to OFF, the forward position signal showing that the shift lever is set to a forward position, the accelerator pedal command value being generated accompanying stepping down of the accelerator pedal, an electric motor command value formed of a backward movement limiting command value that limits backward movement of the haulage vehicle is outputted to the traveling electric motor when the backward movement limiting set value is ON, and an electric motor command value formed of a normal command value not applying backward movement limitation is outputted to the traveling electric motor when the backward movement limiting set value is OFF.

Advantageous Effects of Invention

According to the present invention, it is allowed to provide a technology that is suitable to a haulage vehicle particularly for a mine and suppresses erroneous starting when a vehicle starts. Problems, configurations, and effects other than those described above will be clarified by explanation of embodiments hereinafter described.

DESCRIPTION OF EMBODIMENT

An embodiment of the present invention will be hereinafter explained using the drawings. In all drawings, same configurations are marked with a same reference sign, and duplicated explanation thereof will be omitted.

In the explanations below, a dump truck will be used as a haulage vehicle1. Hereinafter, “left” is the left side in viewing the front from a cab2of the dump truck, and “right” becomes the right side in viewing the front from the cab2.

FIG.1is a drawing that shows a schematic configuration of a mine site in the present embodiment. As shown inFIG.1, in a mine site, there are operated at least one loading machine30that executes excavation work, loading work, and the like, and at least one haulage vehicle1that transports a load such as the crushed stone and dirt excavated by the loading machine30from a loading area to a dumping area.

The haulage vehicle1moves forward toward the loading machine30at a time point t1, and stops at a loading spot at a time point t2. The haulage vehicle1may move forward toward the dumping area at a time point t3when the loading work is completed.

FIG.2shows a left side view of the haulage vehicle1,FIG.3shows a rear view of the haulage vehicle1, andFIG.4shows a left side view of the haulage vehicle1in a dumping attitude. As shown in these drawings, the haulage vehicle1includes the cab2, a vehicle frame3, a vessel4that is mounted on the vehicle frame3so as to be capable of rising/falling, front wheels5, rear wheels6, and hoist cylinders7.

The cab2is arranged for allowing an operator to get on and to operate the haulage vehicle1, and is often disposed in the front left of the haulage vehicle1.

The vehicle frame3configures a framework of the haulage vehicle1, a pair of the front wheels5are arranged in the front of the vehicle frame3, and a pair of the rear wheels6are arranged in the rear of the vehicle frame3. The front wheels5and the rear wheels6are suspended by four suspension cylinders in the front, rear, left, and right which are not illustrated.

Inside the rear of the vehicle frame3, at least one traveling electric motor10is arranged. The traveling electric motor10is connected to the rear wheels6through a reduction gear11. The rear wheels6are driven according to rotation of the traveling electric motor10. The front wheels5are made to be steerable to the left and right by a steering cylinder not illustrated. Between the vehicle frame3and the vessel4, the hoist cylinders7are attached. When the hoist cylinders7extend, the vessel4rises with respect to the vehicle frame3as shown inFIG.4. When the hoist cylinders7retract, the vessel4is seated. At the time of dumping, by raising the vessel4, the dirt and the like mounted on the vessel4are dumped to the rear of the haulage vehicle1.

<Configuration of Travel Control Device20of Haulage Vehicle1>

FIG.5is a block diagram that shows a configuration of a travel control device20of the haulage vehicle1in the present embodiment. Inside the cab2, the travel control device20is provided. To the travel control device20, as an input system, an accelerator pedal12, a brake pedal13, and a shift lever14as operation devices are connected, the shift lever14switching the traveling direction forward or backward. Further, as an input system of the travel control device20, a suspension cylinder pressure sensor16, a vessel angle sensor17, and a vehicle speed sensor18are connected.

As an output system of the travel control device20, the traveling electric motor10is connected.

A command to the traveling electric motor10is effected by the accelerator pedal12, the brake pedal13, and the shift lever14, and movement in the front-rear direction of the haulage vehicle1is instructed. Also, a command to the steering cylinder is effected by a steering wheel not illustrated provided inside the cabin2, and steering of the front wheels5to the left and right is instructed.

The suspension cylinder pressure sensor16detects the pressure of the suspension cylinder.

The vessel angle sensor17detects the tilting angle of the vessel4, and outputs an output value showing the tilting angle to the travel control device20. Therefore, the vessel angle sensor17is equivalent to a tilting angle detector.

The vehicle speed sensor18is provided in the front wheel5, and detects the vehicle speed of the haulage vehicle1from the rotational speed and the rotation direction of the front wheel5.

The travel control device20includes a mounted load value calculation section21, a backward movement limiting determination section22, and an electric motor command value generation section23.

The mounted load value calculation section21calculates the mounted load value of the haulage vehicle1from an output value of the suspension cylinder pressure sensor16(suspension cylinder pressure value). For the technology of calculating the mounted load value from the suspension cylinder pressure value, a technology generally and widely known may be used. Since the mounted load value calculation section21is provided in the travel control device20, the travel control device20has a function as a load measurement device.

The backward movement limiting determination section22determines the backward movement limiting set value using an output value of the vessel angle sensor17, an output value of the vehicle speed sensor18, and a mounted load value calculated by the mounted load value calculation section21. In the present embodiment, the value of a backward movement limiting flag is used as the backward movement limiting set value, the value “1” is explained as ON, and the value “0” is explained as OFF. Inside the backward movement limiting determination section22, a backward movement limiting flag storage region22ais provided. The process content in the backward movement limiting determination section22will be described below.

The electric motor command value generation section23calculates an electric motor command value using a command value of the accelerator pedal12(accelerator pedal command value), a command value of the brake pedal13(brake pedal command value), a command value of the shift lever14(forward position signal, backward position signal), and a value of the backward movement limiting flag stored in the backward movement limiting flag storage region22a, and outputs the electric motor command value having been calculated to the traveling electric motor10. The process content in the electric motor command value generation section23will be described below.

FIG.6is a hardware configuration diagram of the travel control device20. The travel control device20is configured by a computer (travel controller) that includes a CPU231executing calculation, a ROM232storing various processes (programs), a RAM233storing a load measured value and a backward movement limiting flag, an HDD234as a storage device, an input interface235(input I/F) executing sensor inputting and communication, an output interface (output I/F)236, and a bus237connecting these respective constituent elements to each other. The configuration of the computer described above is only an example, and the kind of the hardware such as a processor and a circuit is not limited.

<Process of Travel Control Device20>

A process in each section of the travel control device20will be explained.

<Process of Backward Movement Limiting Determination Section22>

FIG.7is a process flowchart of the backward movement limiting determination section22. The process of the backward movement limiting determination section22will be explained usingFIG.7. The process of the backward movement limiting determination section22is executed periodically.

When the process is started (S11), the backward movement limiting determination section22reads a present value of the backward movement limiting flag stored in the backward movement limiting flag storage region22a(S12). The process proceeds to S13when the backward movement limiting flag at present is “0 (OFF)” (S12/OFF), and the process proceeds to S17when the backward movement limiting flag at present is “1 (ON)” (S12/ON).

The backward movement limiting determination section22determines whether or not the haulage vehicle1has been stopped based on the value of the vehicle speed sensor18(S13). When the haulage vehicle1has not stopped (S13/No), the process is ended (S19). When the haulage vehicle1has been stopped (S13/Yes), the process proceeds to S14.

The backward movement limiting determination section22determines whether or not the loading work to the haulage vehicle1has been started based on variation of the mounted load value (S14). When the mounted load value increases by a constant value or more from a value of the time of the empty load, the backward movement limiting determination section22determines that the loading work to the haulage vehicle1has been started (S14/Yes), sets the value of the backward movement limiting flag to “1 (ON)” (S16), and ends the process (S19).

On the other hand, when the mounted load value does not change from a value of the time of the empty load, the backward movement limiting determination section22determines that the loading work to the haulage vehicle1has not started yet (S14/No), and the process proceeds to S15.

The backward movement limiting determination section22determines whether or not the dumping work of the haulage vehicle1has been started based on an output value of the vessel angle sensor17(S15). When it is determined that the output value of the vessel angle sensor17has changed, the vessel4has risen, and the dumping work has been started (S15/Yes), the backward movement limiting determination section22sets the value of the backward movement limiting flag to “1 (ON)” (S16) and ends the process (S19).

When the value of the vessel angle sensor17does not change, the backward movement limiting determination section22determines that the dumping work has not started yet (S15/No) and ends the process (S19).

In S17, the backward movement limiting determination section22determines whether or not the haulage vehicle1is moving forward based on the value of the vehicle speed sensor18. When it is determined that the haulage vehicle1is not moving forward (S17/No), the backward movement limiting determination section22ends the process (S19). When the haulage vehicle1has moved forward (S17/Yes), the backward movement limiting determination section22rewrites the value of the backward movement limiting flag to “0 (OFF)” (S18), and ends the process (S19).

By executing the process described above, when the haulage vehicle1starts the loading work or the dumping work, the value of the backward movement limiting flag becomes “1 (ON)”. Also, when the haulage vehicle1moves forward in a state the value of the backward movement limiting flag is “1 (ON)”, the value of the backward movement limiting flag becomes “0 (OFF)”.

<Process of Electric Motor Command Value Generation Section23>

FIG.8shows a process flowchart of the electric motor command value generation section23,FIG.9shows a schematic drawing showing normal command value generation of the electric motor command value generation section23, andFIG.10AandFIG.10Bshow schematic drawings showing backward movement limiting command value generation of the electric motor command value generation section23. A process of the electric motor command value generation section23will be explained usingFIGS.8,9,10A,10B. The process of the electric motor command value generation section23is executed periodically.

When the process is started (S21), the electric motor command value generation section23confirms forward/backward of the shift lever14(S22). A forward position signal is outputted to the travel control device20when the shift lever14has been set to the forward position, and a backward position signal is outputted to the travel control device20when the shift lever14has been set to the backward position. The travel control device20determines the position of the shift lever14based on the forward position signal or the backward position signal. The process proceeds to S23when the shift lever14is at the backward position (S22/backward), and the process proceeds to S24when the shift lever14is at the forward position (S22/forward).

In S23, the electric motor command value generation section23confirms the value of the backward movement limiting flag. The process proceeds to S25when the value of the backward movement limiting flag is “1 (ON)” (S23/ON), and the process proceeds to S24when the value of the backward movement limiting flag is “0 (OFF)” (S23/OFF).

In S24, the electric motor command value generation section23generates an electric motor command value as per normal without particularly arranging limitation (normal command value based on an accelerator pedal command value acquired from the accelerator pedal12and a brake pedal command value acquired from the brake pedal13, outputs an electric motor command value configured of the normal command value to the traveling electric motor10(S26), and ends the process (S27).

A method for calculating the electric motor command value from the accelerator pedal command value and the brake pedal command value is a technology generally and widely known. As an example, as shown inFIG.9, there is a method of linearly increasing the electric motor command value according to the magnitude of the accelerator pedal command value. Here, the electric motor command value is a command value that drives the traveling electric motor10, is a value that shows the rotational speed of a motor for example, but is not limited to this, and a torque command value, a speed command value, and the like may be selected freely.

In S25, the electric motor command value generation section23generates an electric motor command value (backward movement limiting command value) applying limitation to the accelerator pedal command value and the brake pedal command value (S25), outputs the electric motor command value configured of the backward movement limiting command value to the traveling electric motor10(S26), and ends the process (S27).

Although the method for applying limitation to a certain electric motor command value is a technology generally and widely known, three examples will be shown in the present embodiment. In the first example, as shown inFIG.10A, a backward movement limiting command value obtained by multiplying a previous electric motor command value (a normal command value to which backward movement limitation is not applied) by a positive constant that is less than 1 is made to be a new electric motor command value. In the second example, as shown inFIG.10B, an upper limit value is arranged with respect to a previous electric motor command value, and a backward movement limiting command value configured of the upper limit value is made to be a new electric motor command value with respect to the previous electric motor command value that is equal to or greater than the upper limit value. In the third example, the electric motor command value is made to be zero (travel is stopped) irrespective of the magnitude of the accelerator pedal command value, and backward movement is entirely prohibited. Using them, for example, the backward moving traveling speed is made to be a speed slower than a traveling speed by the previous electric motor command value or zero.

According to the present embodiment, backward movement motion of the haulage vehicle1when the value of the backward movement limiting flag is “1 (ON)” can be limited. Thus, after the loading or dumping work, the value of the backward movement limiting flag becomes “1 (ON)”, and backward movement limitation is applied. Therefore, by applying limitation to backward movement of the haulage vehicle1only when the operator of the haulage vehicle1tries to make the haulage vehicle1move backward by carelessness after the loading or dumping work, impact caused by collision of the haulage vehicle1and an excavation bench or dumped dirt can be avoided or reduced without deteriorating operability. As a result, fracture damage of the haulage vehicle1can be reduced.

Also, compared to dumping work recognition by the mounted load, the dumping work can be recognized based on inclination of the vessel4before the haulage vehicle1actually dumps the dirt, and backward movement limitation of the haulage vehicle1can be executed at quicker and more suitable timing.

Further, it is allowed to recognize normal forward movement of the haulage vehicle1after the loading or dumping work and to release backward movement limitation, and application of backward movement limitation at unnecessary timing can be prevented.

The present invention is not limited to the embodiment described above, and various alterations and amendments by a person with an ordinary skill in the art are possible within the range of the technical thought disclosed in the present specification. Modifications will be described below.

<Determination of Dumping by Mounted Load Value>

According to the present embodiment, the backward movement limiting determination section22determines that the haulage vehicle1has started the dumping work based on variation of the output value of the vessel angle sensor17. However, it is also possible to detect reduction of the mounted load within the vessel4based on variation of the mounted load value, and to determine that the haulage vehicle1has started the dumping work.

<Determination of Forward Movement by Shift Lever14+Accelerator Pedal12>

According to the present embodiment, the backward movement limiting determination section22determines whether or not the haulage vehicle1is moving forward based on the output value of the vehicle speed sensor18. However, it is also possible to determine forward movement of the haulage vehicle1based on the shift lever command value and the accelerator pedal command value. In concrete terms, the haulage vehicle1is determined to have moved forward when the accelerator pedal12is stepped down and the accelerator pedal command value is outputted to the travel control device20in a state “forward” is selected in the shift lever14.

<Backward Movement Limitation by Rising of Vessel4>

According to the present embodiment, the backward movement limiting determination section22determines presence/absence of the dumping work based on rising of the vessel4and decides to execute backward movement limitation. However, it is also possible to determine execution of backward movement limitation using tilting itself of the vessel4as a reference.

Although a dump truck for a mine was exemplified as the haulage vehicle1in the present embodiment described above, the present invention can be applied also to a working machine such as a wheel loader including a bucket of a front working device and loading the dirt and a water tank truck that stores water in a tank provided in the vehicle. In this case, the present invention can also be applied executing determination only with respect to the loading work without determination with respect to the dumping work. Furthermore, the present invention can be applied also to a transportation vehicle used in a general construction site and the like not for a mine.

REFERENCE SIGNS LIST

1: Haulage vehicle2: Cab3: Vehicle frame4: Vessel5: Front wheel6: Rear wheel7: Hoist cylinder10: Traveling electric motor11: Reduction gear12: Accelerator pedal13: Brake pedal14: Shift lever16: Suspension cylinder pressure sensor17: Vessel angle sensor18: Vehicle speed sensor20: Travel control device21: Mounted load value calculation section21a: Backward movement limiting flag storage region22: Backward movement limiting determination section23: Electric motor command value generation section