Work vehicle state detection system, work vehicle, and work vehicle state detection method

A work vehicle state detection system includes: a travel state detector provided in a work vehicle having a rotating machine and detecting a travel state of the work vehicle; a vibration sensor in the rotating machine; a travel state data acquisition unit acquiring travel state data indicating the travel state; a condition satisfaction determination unit determining whether the travel state satisfies a condition; a vibration detection data acquisition unit acquiring vibration detection data indicating a detection value of the vibration sensor when the travel state satisfies the condition; a normal vibration data storage storing normal vibration data indicating a detection value of the vibration sensor when the rotating machine is normal and the travel state satisfies the condition; and an analysis unit that, based on the vibration detection data and the normal vibration data, analyzes a state of the rotating machine when the vibration detection data is acquired.

FIELD

The present invention relates to a work vehicle state detection system, a work vehicle, and a work vehicle state detection method.

BACKGROUND

A wheel-driven work vehicle such as a dump truck or a wheel loader includes a power source such as an internal combustion engine and a rotating machine such as a transmission device and an axle device. Motive power generated by the power source is transmitted to wheels via the transmission device and the axle device. The wheels rotate, whereby the work vehicle travels.

The rotating machine includes machine parts such as gears and bearings, which form a rotating part. When such a machine part deteriorates, small initial peeling occurs on the surface of the machine part. When the machine part is continued to be used in a state where the initial peeling is left unattended, then the peeling progresses, and eventually, the machine part is broken. In addition, when pieces of the broken machine part are scattered around or damage surrounding machine parts and the damage spreads, then a great maintenance cost and a long maintenance period are required. Therefore, there is a demand for a technique capable of detecting an abnormality such as the initial peeling in the machine part at an early stage before a damage spreads even if the abnormality occurs in the machine part.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

At the stage of initial peeling of the machine part, amounts of generated vibration and abnormal noise are small, and it is difficult to notice abnormalities in the rotating machine of the work vehicle. Therefore, the abnormality in the rotating machine may be recognized after the machine part is broken to spread the damage.

An aspect of the present invention is to accurately recognize a state of the rotating machine of the work vehicle. In the following, the recognition of normality and abnormality of the rotating machine will be described in detail including signs thereof.

Solution to Problem

According to an aspect of the present invention, a work vehicle state detection system comprises: a travel state detection device that is provided in a work vehicle having a rotating machine and detects a travel state of the work vehicle; a vibration sensor provided in the rotating machine; a travel state data acquisition unit that acquires travel state data indicating the travel state; a condition satisfaction determination unit that determines whether or not the travel state satisfies a prescribed condition; a vibration detection data acquisition unit that acquires vibration detection data indicating a detection value of the vibration sensor when the travel state satisfies the prescribed condition; a normal vibration data storage unit that stores normal vibration data indicating a detection value of the vibration sensor when the rotating machine is normal and the travel state satisfies the prescribed condition; and an analysis unit that, based on the vibration detection data and the normal vibration data, analyzes a state of the rotating machine when the vibration detection data is acquired.

Advantageous Effects of Invention

According to the aspect of the present invention, the state of the rotating machine of the work vehicle can be accurately recognized.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the drawings; however, the present invention is not limited thereto. Components of the embodiments described below can be appropriately combined with one another. In some cases, some components are not used.

FIG.1is a perspective view of an example of a work vehicle100according to the present embodiment as seen from the rear.FIG.2is a diagram schematically illustrating the example of the work vehicle100according to the present embodiment. In the present embodiment, the work vehicle100is a dump truck that travels with a load at a digging site of a mine. In the following description, the work vehicle100is appropriately referred to as a dump truck100.

In the present embodiment, the dump truck100includes a driver's cab in which a driver boards. The dump truck100is a manned dump truck operated by a driver. Further, in the present embodiment, the dump truck100is a live-axle dump truck.

As illustrated inFIGS.1and2, the dump truck100includes a power source70, a vehicle body frame110, a dump body120, and a travel device130.

The power source70is supported by the vehicle body frame110. The power source70includes an internal combustion engine such as a diesel engine. The power source70may include a generator that operates by motive power generated by the internal combustion engine and an electric motor that operates by electric power generated by a generator.

The vehicle body frame110supports the dump body120. The dump body120is a member on which a load is loaded.

The travel device130supports the vehicle body frame110. The travel device130includes wheels150on which tires140are mounted, suspension devices160, and a steering device170.

The wheels150are supported by the suspension devices160. The wheels150include front wheels150F and rear wheels150R. The rear wheels150R rotate about a rotation axis AX.

In the following description, a direction parallel to the rotation axis AX will be appropriately referred to as a vehicle width direction, a travel direction of the dump truck100will be appropriately referred to as a front-rear direction, and a direction orthogonal to each of the vehicle width direction and the front-rear direction will be appropriately referred to as a vertical direction.

One side in the front-rear direction is a front side, and an opposite side to the front side is a rear side. One side in the vehicle width direction is a right side, and an opposite side to the right side is a left side. One side in the vertical directions is an upper side, and an opposite side to the upper side is a lower side. The front wheels150F are arranged in front of the rear wheels150R. The front wheels150F are arranged on both sides in the vehicle width direction. The rear wheels150R are arranged on both sides in the vehicle width direction. The dump body120is disposed above the vehicle body frame110.

The suspension devices160support the wheels150. Each of the suspension devices160includes a suspension cylinder161that supports the wheels150. The suspension cylinder161is disposed between the wheels150and the vehicle body frame110. Hydraulic oil is enclosed in the suspension cylinder161. The suspension cylinder161expands and contracts according to an uneven state of a road surface on which the travel device130travels. The suspension cylinder161expands and contracts, whereby a pressure of the hydraulic oil sealed inside the suspension cylinder161fluctuates.

The steering device170steers the front wheels150F. The steering device170operates when a driver operates a steering wheel disposed in the driver's cab.

The travel device130includes a rotating machine1that transmits the motive power generated by the power source70to the rear wheels150R. The rotating machine1includes an axle device1A and a transmission device1B. The motive power generated by the power source70is transmitted to the axle device1A via the transmission device1B. The transmission device1B rotates a drive shaft3. The drive shaft3applies a rotational force to the axle device1A. The axle device1A transmits the motive power of the power source70, which is supplied via the transmission device1B and the drive shaft3, to the rear wheels150R. The rear wheels150R rotate about the rotation axis AX by the supplied motive power. Thus, the travel device130travels.

Further, the dump truck100includes a rotational speed sensor410, a pressure sensor420, an accelerator opening sensor430, a steering angle sensor440, a position sensor60, a notification device80, a communication device180, a control device200, and a vibration analysis device300.

The rotational speed sensor410detects a rotational speed N of the drive shaft3per unit time, the drive shaft3applying a rotational force to the axle device1A. A rotational speed which is the rotational speed N of the drive shaft3per unit time is detected, whereby a travel speed V of the dump truck100is detected.

The pressure sensor420detects the pressure P of the hydraulic oil sealed in the suspension cylinder161. The pressure sensor420detects the pressure P of the hydraulic oil in the suspension cylinder161, and detects a load acting on the suspension cylinder161. The pressure P of the hydraulic oil in the suspension cylinder161fluctuates according to the uneven state of the road surface on which the travel device130travels. The pressure sensor420functions as a road surface state sensor that detects the uneven state of the road surface. The pressure P of the hydraulic oil in the suspension cylinder161is detected, whereby the uneven state of the road surface is detected.

Further, the pressure P of the hydraulic oil in the suspension cylinder161fluctuates according to a weight of the load loaded on the dump body120. The pressure sensor420functions as a load sensor that detects the weight of the load loaded on the dump body120.

The accelerator opening sensor430detects an operation amount (depression amount) of an accelerator pedal73. An accelerator opening W (throttle opening) of a throttle valve of the power source70is adjusted based on the operation amount of the accelerator pedal73. The accelerator pedal73functions as an operating device that adjusts an output of the power source70that drives the rotating machine1. An operation amount of the operating device includes the accelerator opening W. The accelerator opening W is adjusted, whereby the output of the power source70that drives the rotating machine1is adjusted.

The steering angle sensor440detects a steering angle θ of the steering device170. When the operation angle θ is 0 [°], the travel device130goes straight. When the steering angle θ increases, the travel device130turns. The steering angle θ of the steering device170is detected, whereby whether the travel device130is traveling straight or turning is detected.

The position sensor60detects an absolute position indicating a position of the dump truck100in a global coordinate system by using a global navigation satellite system (GNSS). An example of the global navigation satellite system is a global positioning system (GPS). The position sensor60includes a GPS receiver.

The notification device80is mounted on the dump truck100. The notification device80is disposed in the driver's cab and notifies the driver of data. The notification device80includes at least one of a display device, a light emitting device, and a sound output device. The display device includes a flat panel display such as a liquid crystal display (LCD) and an organic electroluminescence display (OELD). The light emitting device includes a light source such as a light emitting diode (LED). The sound output device includes a siren or a voice output device, which is capable of generating a warning sound. The notification device notifies the driver of data by using at least one of display data displayed on the display device, light emitted from the light emitting device, and a sound output from the sound output device.

The communication device180is capable of communicating with an external device. The communication device180is connected to the control device200.

FIG.3is a view of a part of the axle device1A according to the present embodiment as seen from the rear.FIG.4is a plan view illustrating the example of the axle device1A according the embodiment of the present invention. In the present embodiment, the axle device1A is a rear axle that drives the rear wheels150R. The axle device1A includes an axle housing2. The axle housing2is a tubular member. Pluralities of machine parts such as a gears10or bearings20are housed in the internal space of the axle housing2.

The axle housing2is supported by the vehicle body frame110via the suspension devices160. Vibration sensors50are provided on the axle housing2. A plurality of the vibration sensors50are provided on the outer surface of the axle housing2. The plurality of vibration sensors50are provided on the upper surface of the axle housing2at intervals. The vibration sensors50are provided on the axle housing2so as to detect a vibration in the vertical direction.

In the present embodiment, the vibration sensors50provided on the axle housing2include four vibration sensors50A,50B,50C, and50D. The vibration sensor50A is provided at the center of the upper surface of the axle housing2in the vehicle width direction and the center thereof in the front-rear direction. The vibration sensor50B is provided at the center of the upper surface of the axle housing2in the vehicle width direction and in front of the vibration sensor50A. The vibration sensor50C is provided at the center of the upper surface of the axle housing2in the front-rear direction and to the left of the vibration sensor50A. The vibration sensor50D is provided at the center of the upper surface of the axle housing2in the front-rear direction and to the right of the vibration sensor50A. The number of vibration sensors50provided on the axle housing2may be two or three, or may be any number of five or more. The number of vibration sensors50provided on the axle housing2may be one.

As illustrated inFIG.4, the axle device1A includes the axle housing2, a differential disposed in an internal space2H of the axle housing2and coupled to the drive shaft3, and an axle shaft to which the rotational force of the drive shaft3is transmitted via the differential4. The axle shaft rotates, whereby the rear wheels150R of the travel device130rotate.

The axle housing2includes a differential body2A that houses the differential4, and side bodies2B individually connected to right and left portions of the differential body2A.

The drive shaft3rotates by a driving force generated by the engine. The drive shaft3extends in the front-rear direction and rotates about a rotation axis BX. The rotation axis BX extends in the front-rear direction.

The motive power generated by the power source70is transmitted to the axle device1A via the transmission device1B and the drive shaft3.

When the drive shaft3rotates about the rotation axis BX, the axle shaft rotates about the rotation axis AX. The rotation axis AX extends in the vehicle width direction. The rotation axis AX and the rotation axis BX are substantially orthogonal to each other. When the axle shaft rotates about the rotation axis AX, the rear wheels150R connected to the axle shaft rotate about the rotation axis AX.

FIG.5is a functional block diagram illustrating an example of a state detection system1000according to the present embodiment. As illustrated inFIG.5, the state detection system1000includes the control device200, the vibration analysis device300, a travel state detection device400, and the vibration sensor50.

The state detection system1000also includes the position sensor60, the notification device80, and the communication device180. The state detection system1000is capable of communicating with a server500via the communication device180and a communication device190.

The state detection system1000is provided on the dump truck100. The server500is provided outside the dump truck100.

The communication device190is connected to the server500. The communication device180of the state detection system1000and the communication device190of the server500communicate with each other via a communication network. The communication network includes the Internet. The communication network may include a mobile phone communication network.

The control device200includes a computer system. The control device200includes an arithmetic processing device210including a processor such as a central processing unit (CPU), a storage device220including a volatile memory such as a random access memory (RAM) and a non-volatile memory such as a read only memory (ROM), and an input/output interface230.

The vibration analysis device300includes a computer system. The vibration analysis device300includes an arithmetic processing device310including a processor such as a CPU, a storage device320including a volatile memory such as a RAM and a non-volatile memory such as a ROM, and an input/output interface330.

The server500includes a computer system. The server500includes an arithmetic processing device510including a processor such as a CPU, a storage device520including a volatile memory such as RAM and a non-volatile memory such as ROM, and an input/output interface530.

The input/output interface230of the control device200includes an interface circuit that connects the arithmetic processing device210and the storage device220to such external devices. The vibration analysis device300, the travel state detection device400, the position sensor60, the notification device80, and the communication device180are connected to the input/output interface230.

The input/output interface330of the vibration analysis device300includes an interface circuit that connects the arithmetic processing device310and the storage device320to such external devices. The control device200, the travel state detection device400, and the vibration sensor50are connected to the input/output interface330.

The input/output interface530of the server500includes an interface circuit that connects the arithmetic processing device510and the storage device520to such an external device. The communication device190is connected to the input/output interface530.

The travel state detection device400is provided in the dump truck100. The travel state detection device400detects a travel state of the dump truck100. In the present embodiment, the travel state detection device400includes the rotational speed sensor410, the pressure sensor420, the accelerator opening sensor430, and the steering angle sensor440.

The travel state of the dump truck100, which is detected by the travel state detection device400, includes at least one of: the rotational speed of the drive shaft3per unit time, which is detected by the rotational speed sensor410; the pressure of the suspension cylinder161, which is detected by the pressure sensor420; the accelerator opening that adjusts the output of the power source70, the accelerator opening being detected by the accelerator opening sensor430; and the steering angle of the steering device170, which is detected by the steering angle sensor440.

The vibration sensor50is provided in the axle housing2of the axle device1A. The vibration sensor50detects the vibration of the axle device1A.

The arithmetic processing device210of the control device200includes: a travel state data acquisition unit240that acquires travel state data indicating a travel state of the dump truck100; a position acquisition unit250that acquires position data indicating the position of the dump truck100; a condition satisfaction determination unit260that determines whether or not the travel state of the dump truck100satisfies prescribed conditions; and a trigger unit270that outputs a trigger signal to the vibration analysis device300.

The storage device220of the control device200includes a prescribed condition storage unit221, a position data storage unit222, and a data accumulation unit223.

The travel state data acquisition unit240acquires travel state data from the travel state detection device400. The travel state data acquisition unit240includes a rotational speed acquisition unit241that acquires the rotational speed N of the drive shaft3from the rotational speed sensor410, a pressure acquisition unit242that acquires the pressure P of the suspension cylinder161from the pressure sensor420, and an accelerator opening acquisition unit243that acquires the accelerator opening W from the accelerator opening sensor430, and a steering angle acquisition unit244that acquires the steering angle θ of the steering device170from the steering angle sensor440.

The position acquisition unit250acquires the position of the dump truck100from the position sensor60.

The prescribed condition storage unit221stores prescribed conditions regarding the travel state of the dump truck100. The prescribed conditions define the travel state of the dump truck100in which a state of the axle device1A can be detected while a disturbance is suppressed when the vibration sensor50detects the vibration of the axle device1A. The matter that the travel state of the dump truck100satisfies the prescribed conditions means that the vibration sensor50can accurately detect the vibration of the axle device1A while the disturbance applied to the vibration sensor50is suppressed.

The position data storage unit222stores position data indicating the position of the dump truck100when the travel state satisfies the prescribed conditions based on the position of the dump truck100, which is acquired by the position acquisition unit250, and based on a travel state of the dump truck100, which is acquired by the travel state data acquisition unit240when the dump truck100travels at the position acquired by the position acquisition unit250. The position data storage unit222stores the position of the dump truck100when the dump truck100travels while satisfying the prescribed conditions.

The data accumulation unit223stores the travel state data acquired by the travel state data acquisition unit240and the vibration detection data of the vibration sensor50.

The condition satisfaction determination unit260determines whether or not the travel state acquired by the travel state data acquisition unit240satisfies the prescribed conditions based on the prescribed conditions stored in the prescribed condition storage unit221. The condition satisfaction determination unit260outputs determination data to the vibration analysis device300.

The trigger unit270outputs the trigger signal for starting a vibration analysis to the vibration analysis device300when the state in which the travel state satisfies the prescribed conditions is maintained for a prescribed time. In the present embodiment, the prescribed time is, for example, five [seconds].

The arithmetic processing device310of the vibration analysis device300includes: a travel state data acquisition unit340that acquires the travel state data indicating the travel state of the dump truck100; a vibration detection data acquisition unit350that acquires the vibration detection data indicating the detection value of the vibration sensor50; an analysis unit360that analyzes the state of the axle device1A when the vibration detection data acquisition unit350acquires the vibration detection data; and an output unit370that outputs an analysis result of the analysis unit360.

The storage device320of the vibration analysis device300includes a normal vibration data storage unit321, a correlation data storage unit322, and a data accumulation unit323.

The travel state data acquisition unit340acquires the travel state data from the travel state detection device400. The travel state data acquisition unit340of the vibration analysis device300has the same function as the travel state data acquisition unit240of the control device200.

The normal vibration data storage unit321stores normal vibration data indicating a detection value of the vibration sensor50when the axle device1A is normal and the travel state of the dump truck100satisfies the prescribed conditions. The matter that the axle device1A is normal means that each of the machine parts of the axle device1A is normal, and includes a state in which the machine part of the axle device1A does not deteriorate, a state in which a surface thereof is not peeled, and a state in which the machine part is not broken. For example, when the axle device1A is new, the axle device1A is normal. For example, the normal vibration data is collected when the axle device1A is new and the dump truck100travels under the prescribed conditions, and is stored in the normal vibration data storage unit321. The matter that the axle device1A is normal is not limited to the matter that the axle device1A is new.

The correlation data storage unit322stores correlation data indicating a relationship between the rotational speed N of the drive shaft3and vibration characteristics of the axle device1A when the machine part of the axle device1A is abnormal. The correlation data is used when an abnormal machine part is specified from among the plurality of machine parts of the axle device1A.

The data accumulation unit323stores the travel state data acquired by the travel state data acquisition unit340and the vibration detection data of the vibration sensor50.

The vibration detection data acquisition unit350acquires, from the vibration sensor50, the vibration detection data indicating the detection value of the vibration sensor50. In the present embodiment, the vibration detection data acquisition unit350acquires the vibration detection data of the vibration sensor50when the travel state of the dump truck100satisfies the prescribed conditions. The determination data of the condition satisfaction determination unit260is supplied to the vibration detection data acquisition unit350. The vibration detection data acquisition unit350acquires vibration detection data of the vibration sensor50when the condition satisfaction determination unit260determines that the travel state of the dump truck100satisfies the prescribed conditions, and stores the vibration detection data in the data accumulation unit323.

The analysis unit360analyzes a state of the axle device1A when the vibration detection data acquisition unit350acquires the vibration detection data based on the normal vibration data stored in the normal vibration data storage unit321, and based on the vibration detection data acquired by the vibration detection data acquisition unit350.

The vibration detection data is vibration waveform data detected by the vibration sensor50when the travel state satisfies the prescribed conditions. The normal vibration data is also vibration waveform data detected by the vibration sensor50when the travel state satisfies the prescribed conditions. That is, the travel state of the dump truck100when the vibration detection data is acquired and the travel state of the dump truck100when the normal vibration data is acquired are the same conditions (prescribed conditions).

When the machine part of the axle device1A is normal when the vibration detection data is acquired, the vibration detection data is substantially equal to the normal vibration data. Meanwhile, when the machine part of the axle device1A is abnormal when the vibration detection data is acquired, the vibration detection data is different from the normal vibration data. That is, when the axle device1A is normal, the vibration detection data and normal vibration data are substantially equal to each other, and when the axle device1A is abnormal, the vibration detection data and normal vibration data are different from each other. The matter that the axle device1A is abnormal means that the machine part of the axle device1A is abnormal, and includes at least one of a state in which the machine part of the axle device1A deteriorates, a state in which a surface thereof is peeled, and a state in which the machine part is broken.

The analysis unit360compares the normal vibration data stored in the normal vibration data storage unit321and the vibration detection data acquired by the vibration detection data acquisition unit350with each other, and can thereby determine whether the axle device1A is abnormal.

Further, the analysis unit360can specify the abnormal machine part based on the correlation data stored in the correlation data storage unit322, and based on the vibration detection data acquired by the vibration detection data acquisition unit350.

The output unit370outputs the analysis result of the analysis unit360. In the present embodiment, the output unit370outputs the analysis result to the data accumulation unit323. The data accumulation unit323stores the analysis result. The output unit370also outputs the analysis result to the control device200. The data accumulation unit223of the control device200stores the analysis result. The control device200also outputs the analysis result to the notification device80. The control device200also transmits the analysis result to the server500via the communication device180. The output unit370may output the analysis result to the notification device80or the server500without the control device200.

Next, the prescribed conditions will be described. The prescribed condition storage unit221stores the prescribed conditions regarding the travel state of the dump truck100. The prescribed conditions define the travel state of the dump truck100in which a state of the axle device1A can be detected while a disturbance is suppressed when the vibration sensor50detects the vibration of the axle device1A.

FIG.6is a diagram illustrating an example of the prescribed conditions according to the present embodiment. As illustrated inFIG.6, the prescribed conditions include: a prescribed condition regarding the rotational speed N of the drive shaft3; a prescribed condition regarding the pressure P of the suspension cylinder161; a prescribed condition regarding the accelerator opening W; and a prescribed condition regarding the steering angle θ of the steering device170.

The prescribed condition regarding the rotational speed N of the drive shaft3includes that the rotational speed N of the drive shaft3per unit time is equal to or greater than a prescribed rotational speed Nr. When the rotational speed N of the drive shaft3, which is detected by the rotational speed sensor410, is equal to or greater than the prescribed rotational speed Nr, the prescribed condition is satisfied, and when the rotational speed N is less than the prescribed rotational speed Nr, the prescribed condition is not satisfied.

When the axle device1A is not operating, the axle device1A does not vibrate in the first place. Even if the vibration sensor50detects the vibration of the axle device1A, it is difficult to determine whether or not the machine part is abnormal from the vibration detection data of the vibration sensor50. In order to determine whether or not the machine part is abnormal, it is necessary to detect the vibration while the axle device1A is operating. Hence, when the vibration is detected, the rotational speed N of the drive shaft3needs to be equal to or greater than the prescribed rotational speed Nr.

The rotational speed N of the drive shaft3corresponds to the travel speed V of the dump truck100. Therefore, the prescribed conditions may include that the travel speed V of the dump truck100is equal to or greater than a prescribed travel speed Vr. When the travel speed V of the dump truck100is equal to or greater than the prescribed travel speed Vr, the prescribed condition is satisfied, and when the travel speed V is less than the prescribed travel speed Vr, the prescribed condition is not satisfied.

The prescribed condition regarding the rotational speed N of the drive shaft3includes that a fluctuation amount ΔN of the rotational speed N of the drive shaft3per unit time is within a first fluctuation range±ΔNr. When the fluctuation amount ΔN derived from the detection data of the rotational speed sensor410is within the first fluctuation range±ΔNr, the prescribed condition is satisfied, and when the fluctuation amount ΔN is out of the first variation range±ΔNr, the prescribed condition is not satisfied.

The matter that the fluctuation amount ΔN is large means that a fluctuation amount ΔV of the travel speed V of the dump truck100per unit time is large. That is, the matter that the fluctuation amount ΔN is large means that the dump truck100repeats acceleration or deceleration. When the fluctuation amount ΔV of the travel speed V is large, the vibration characteristics of the axle device1A change, and accordingly, accuracy of a result of vibration analysis performed based on the vibration detection data of the vibration sensor50may decrease. Hence, when the vibration of the axle device1A is detected, the fluctuation amount ΔN of the rotational speed N of the drive shaft3needs to remain within the first fluctuation range±ΔNr, that is, the fluctuation amount ΔV of the travel speed V of the dump truck100needs to remain within the first fluctuation range±ΔVr.

The prescribed condition regarding the pressure P of the suspension cylinder161includes that a fluctuation amount ΔP of the pressure P of the suspension cylinder161per unit time is within a second fluctuation range±ΔPr. When the fluctuation amount ΔP derived from the detection data of the pressure sensor420is within the second fluctuation range±ΔPr [%], the prescribed condition is satisfied, and when the fluctuation amount ΔP is out of the second fluctuation range±Pr [%], the prescribed condition is not satisfied.

The matter that the fluctuation amount ΔP is large means that the road surface on which the dump truck100travels is highly uneven. When the dump truck100travels on the road surface where the unevenness is severe, the vibration characteristics of the axle device1A change, and accordingly, the accuracy of the result of the vibration analysis performed based on the detection data of the vibration sensor50may decrease. Hence, when the vibration of the axle device1A is detected, the fluctuation amount ΔP of the pressure P of the suspension cylinder161needs to remain within the second fluctuation range±ΔPr.

The prescribed condition regarding the accelerator opening W includes that the accelerator opening W is equal to or greater than a prescribed accelerator opening Wr (prescribed adjustment amount). When the accelerator opening W detected by the accelerator opening sensor430is equal to or more than the prescribed accelerator opening Wr [%], the prescribed condition is satisfied, and when the accelerator opening W is less than the prescribed accelerator opening Wr [%], the prescribed condition is not satisfied.

When the accelerator pedal73is operated and the drive shaft3rotates, the gears10of the axle device1A also rotate. When a gear10A and a gear10B mesh with each other and the gear10A rotates, a front tooth surface of the gear10A and a rear tooth surface of the gear10B come into contact with each other. Meanwhile, when the accelerator pedal73is not operated and is in a so-called engine brake state, a backlash (play between gears) causes the front tooth surface of the gear10A and the rear tooth surface of the gear10B to separate from each other, or a rear tooth surface of the gear10A and a front tooth surface of the gear10B to come into contact with each other. That is, a contact state of the tooth surfaces of the gears10changes based on whether or not the accelerator pedal73is operated or based on the amount of operation thereof. When the contact state of the tooth surfaces of the gears10changes, the vibration characteristics of the axle device1A change, and accordingly, the accuracy of the result of the vibration analysis performed based on the detection data of the vibration sensor50may decrease. Hence, when the vibration of the axle device1A is detected, the accelerator opening W needs to be equal to or greater than the prescribed accelerator opening Wr in order to reduce an effect of the backlash and to constantly maintain the contact state of the tooth surfaces of the gears10.

The prescribed condition regarding the steering angle θ of the steering device170includes that the steering angle θ remains within a prescribed steering angle±θr. When the steering angle θ of the steering device170, which is detected by the steering angle sensor440, remains within the prescribed steering angle±θr, the prescribed condition is satisfied, and when the steering angle θ is out of the prescribed steering angle±θr, the prescribed condition is not satisfied.

The matter that the steering angle θ is small means that the dump truck100is traveling straight, and the matter that the steering angle θ is large means that the dump truck100is turning. The vibration of the axle device1A is preferably detected under certain conditions. Further, when the dump truck100is turning, a difference occurs between a rotational speed of the right gear10and a rotational speed of the left gear10in the vehicle width direction due to an action of the differential4, and the vibration characteristics of the axle device1A change. Accordingly, the accuracy of result of the vibration analysis performed based on the detection data of the vibration sensor50may decrease. Hence, when the vibration of the axle device1A is detected, the steering angle θ needs to remain within the prescribed steering angle±θr, that is, the dump truck100needs to be traveling substantially straight.

FIG.7is a diagram illustrating vibration spectrum characteristics of normal vibration data and vibration detection data according to the present embodiment.FIG.7illustrates vibration spectra acquired by performing a fast Fourier transform individually for the normal vibration data and the vibration detection data. InFIG.7, a horizontal axis represents frequency and a vertical axis represents vibration intensity.

As illustrated inFIG.7, the acquired vibration spectra are different between when the machine part is normal and when the machine part is abnormal. In the present embodiment, the analysis unit360determines that the machine part is abnormal when a difference ΔS between a peak value of the vibration spectrum, which is calculated based on the normal vibration data, and a peak value of the vibration spectrum, which is calculated based on the vibration detection data, is equal to or greater than a predetermined threshold value.

In the present embodiment, the analysis unit360not only determines whether or not the machine part is abnormal but also specifies such an abnormal machine part. The analysis unit360specifies the abnormal machine part based on the correlation data stored in the correlation data storage unit322.

FIG.8is a table illustrating an example of correlation data according to the present embodiment. As illustrated inFIG.8, the correlation data storage unit322stores correlation data indicating relationships between the rotational speed No of the drive shaft3and the vibration characteristics of the axle device1A, which are detected by the vibration sensor50when the machine part is abnormal. The correlation data is derived by, for example, a simulation performed based on design data of the axle device1A. The design data of the axle device1A includes shape data of the gears10, such as a cutting edge diameter, a reference diameter, and the number of teeth, and shape data of the bearings20, such as a size of each inner ring.

For example, when an inner ring of the first bearing is abnormal and the drive shaft3rotates at the prescribed rotational speed No, the axle device1A vibrates with a first vibration characteristic. In the example illustrated inFIG.8, when the drive shaft3rotates at the rotational speed No when the inner ring of the first bearing is abnormal, a vibration of a frequency Nb1 [Hz] is detected most significantly.

Further, when an outer ring of the first bearing is abnormal and the drive shaft3rotates at the rotational speed No, the axle device1A vibrates with a second vibration characteristic. In the example illustrated inFIG.8, a vibration of a frequency Nb2 [Hz] is detected most significantly.

Likewise, when an inner ring of a second bearing is abnormal, a vibration of a frequency Nb3 [Hz] is detected significantly, and when an outer ring of the second bearing is abnormal, a vibration of a frequency Nb4 [Hz] is detected significantly.

Further, when the first gear is abnormal (tooth lack), the vibration of the frequency Ng1 [Hz] is detected most significantly, when the first gear is abnormal (causes tooth surface wear), the vibration of the frequency Ng2 [Hz] is detected most significantly, when the second gear is abnormal (causes tooth lack), the vibration of the frequency Ng3 [Hz] is detected most significantly, and when the second gear is abnormal (causes tooth surface wear), the vibration of the frequency Ng4 [Hz] is detected most significantly.

As described above, the vibration characteristics of the axle device1A change based on the machine part in which the abnormality has occurred. The correlation data indicating the vibration characteristics of the axle device1A, which change based on the machine part in which the abnormality has occurred is derived in advance by simulation and is stored in the correlation data storage unit322. The correlation data may be derived by an actual experiment.

The analysis unit360can specify the abnormal machine part based on the correlation data stored in the correlation data storage unit322and the vibration detection data detected by the vibration sensor50. For example, when the vibration sensor50detects the vibration of the frequency Nb1 [Hz] most significantly, the analysis unit360determines that the inner ring of the first bearing is abnormal. Further, when the vibration sensor50detects the vibration of the frequency Ng1 [Hz] most significantly, the analysis unit360determines that the first gear is abnormal (causes tooth lack).

The correlation data illustrated inFIG.8is an example. Actually, the correlation data is derived for each of the plurality of rotational speeds N. Further, correlation data based on various parameters are derived, the correlation data including correlation data about a frequency of an acceleration component of the vibration, correlation data about a frequency of a velocity component of the vibration, and correlation data about a frequency of a displacement component of the vibration.

FIGS.9and10are flowcharts illustrating an example of a state detection method according to the present embodiment. Steps SA1to SA8illustrated inFIG.9are processing of the control device200, and Steps SB1to SB8illustrated inFIG.10are processing of the vibration analysis device300.

The processing of the control device200will be described with reference toFIG.9. The travel state data acquisition unit240of the control device200acquires the travel state data, which indicates the travel state of the dump truck100, from the travel state detection device400(Step SA1).

The condition satisfaction determination unit260determines whether or not the travel state acquired by the travel state data acquisition unit240satisfies the prescribed conditions stored in the prescribed condition storage unit221(Step SA2).

When it is determined in Step SA2that the travel state does not satisfy the prescribed conditions (Step SA2: No), the processing returns to Step SA1, where the travel state data acquisition unit240continues to acquire the travel state data.

In Step SA2, when it is determined that the travel state satisfies the prescribed conditions (Step SA2: Yes), the trigger unit270determines whether or not the elapsed time from the point of time when it is first determined that the prescribed conditions are satisfied exceeds a prescribed time that is predetermined (step SA3).

In Step SA3, when it is determined that the elapsed time does not exceed a prescribed time (Step SA3: No), the process returns to Step SA1, where the travel state data acquisition unit240continues to acquire the travel state data, and the trigger unit270determines whether or not the elapsed time from the point of time when the travel state satisfies the prescribed conditions exceeds the prescribed time.

When it is determined in Step SA3that the elapsed time exceeds the prescribed time (Step SA3: Yes), the trigger unit270outputs a trigger signal to the analysis unit360(Step SA4). That is, the trigger unit270outputs the trigger signal to the analysis unit360when it is determined that a state in which the travel state of the dump truck100satisfies the prescribed conditions is maintained for the prescribed time.

As will be described later, the output unit370of the vibration analysis device300outputs an analysis result indicating that the machine part is abnormal and an analysis result indicating the machine part specified as abnormal. The input/output interface230of the control device200acquires the analysis results output from the vibration analysis device300(Step SA5). This means acquisition of the analysis results of Step SB5illustrated inFIG.10

The input/output interface230outputs the analysis results to the notification device80. The notification device80notifies the driver of the dump truck100of the analysis results (Step SA6). When the analysis unit360determines that the machine part is abnormal, if the notification device80includes a display device, then the notification device80displays display data indicating that the machine part is abnormal. When the notification device80includes a sound output device, the notification device80outputs a sound indicating that the machine part is abnormal. The notification device80may display data indicating that the machine part is normal, or may output a sound indicating that the machine part is normal.

The input/output interface230also outputs the analysis results to the data accumulation unit223. The data accumulation unit223stores the analysis results (Step SA7).

The input/output interface230also outputs the analysis results to the communication device180. The communication device180transmits the analysis results to the server500(Step SA8).

An abnormality determination unit540of the arithmetic processing device510determines whether or not the axle device1A of the dump truck100is abnormal based on the analysis results. Further, the analysis results of the axle device1A are transmitted to the server500from each of a plurality of the dump trucks100. The abnormality determination unit540determines whether or not each of the axle devices1A of the plurality of dump trucks100is abnormal. Analysis results of the plurality of axle devices1A and determination results of abnormalities thereof are stored in a data accumulation unit550of the storage device520. A maintainer of the dump truck100can maintain the dump truck100based on the analysis results or such abnormality determination results, which are stored in the data accumulation unit550.

In the present embodiment, processing (Step SA6) of the notification device80for notifying the driver of the dump truck100of the analysis results may be omitted.

Next, the processing of the vibration analysis device300will be described with reference toFIG.10. Like the travel state data acquisition unit240of the control device200, the travel state data acquisition unit340of the vibration analysis device300also acquires travel state data, which indicates the travel state of the dump truck100, from the travel state detection device400. The travel state data acquired by the travel state data acquisition unit240and the travel state data acquired by the travel state data acquisition unit340are the same data. Further, the vibration detection data acquisition unit350of the vibration analysis device300acquires the vibration detection data of the axle device1A from the vibration sensor50(Step SB1).

The data accumulation unit323stores the vibration detection data acquired by the vibration detection data acquisition unit350(Step SB2). The data accumulation unit323sequentially stores a plurality of vibration detection data in accordance with the elapsed time.

When the state in which the travel state satisfies the prescribed conditions is maintained for the prescribed time, the analysis unit360acquires the trigger signal output from the trigger unit270. As mentioned above, the trigger unit270outputs the trigger signal to the analysis unit360(Step SA4). The analysis unit360acquires, from the data accumulation unit323, vibration detection data acquired during a period between a current point of time tn when the trigger signal is acquired and a preceding point of time ta, which is a time preceding by a prescribed time from the current point of time tn (Step SB3).

Further, the analysis unit360acquires the normal vibration data from the normal vibration data storage unit321(Step SB4).

The analysis unit360analyzes the state of the axle device1A based on the vibration detection data acquired from the data accumulation unit323during the period between the current point of time to and the preceding point of time ta. Based on the normal vibration data stored in the normal vibration data storage unit321and the vibration detection data acquired in Step SB3, the analysis unit360analyzes the state of the axle device1A at the time when the travel state data acquisition unit340acquires the vibration detection data during the prescribed time while the travel state satisfies the prescribed conditions (Step SB5).

As described with reference toFIG.7, the analysis unit360calculates the vibration spectrum, for example, by performing the fast Fourier transform for each of the normal vibration data and the vibration detection data.

The analysis unit360compares the normal vibration data and the vibration detection data with each other to determine whether or not machine part of the axle device1A is abnormal (Step SB6).

As described with reference toFIG.7, the analysis unit360determines whether or not the machine part is abnormal based on whether or not the difference ΔS between the peak value of the vibration spectrum, which is calculated based on the normal vibration data, and the peak value of the vibration spectrum, which is calculated based on the vibration detection data, is equal to or greater than the predetermined threshold value.

In Step SB6, when the difference ΔS is less than the threshold value and it is determined that machine part is not abnormal (Step SB6: No), the output unit370outputs an analysis result indicating that the machine part is not abnormal (Step SB8).

In Step SB6, when the difference ΔS is equal to or greater than the threshold value and it is determined that machine part is abnormal (Step SB6: No), the analysis unit360specifies such an abnormal machine part based on the correlation data stored in the correlation data storage unit322and the vibration detection data (Step SB7).

As described with reference toFIG.8, the correlation data storage unit322stores the correlation data indicating the relationships between the rotational speed N of the drive shaft3and the vibration characteristics of the axle device1A when the machine part is abnormal. When the rotational speed N of the drive shaft3is the rotational speed No and the frequency at which the difference ΔS as illustrated inFIG.7is equal to or greater than the threshold value is Ng1 for example, the analysis unit360can specify the first gear as abnormal (causing tooth lack).

The output unit370outputs the analysis result indicating that the machine part is abnormal and the analysis result indicating the machine part specified as abnormal (Step SB8).

As mentioned above, the output unit370outputs the analysis results to the control device200. The input/output interface230of the control device200acquires the analysis results output from the vibration analysis device300(Step SA5).

As described above, according to the present embodiment, the state of the axle device1A is analyzed based on the vibration detection data detected when the travel state of the dump truck100satisfies the prescribed conditions. As a result, the state of the axle device1A can be analyzed under a condition where the travel state is fixed. Further, when the travel state satisfies the prescribed conditions, the vibration detection data detected by the vibration sensor50is suppressed from being affected by the disturbance. Hence, the state of the axle device1A can be accurately recognized based on the analysis result of the vibration detection data, and the abnormality of the machine part can be detected at an early stage.

Other Embodiments

In the above-mentioned embodiment, the travel state is detected by the travel state detection device400, and the state of the axle device1A is analyzed based on the vibration detection data detected by the vibration sensor50when the travel state detected by the travel state detection device400satisfies the prescribed conditions. For example, when the position data indicating the position of the dump truck100when the travel state of the dump truck100satisfies the prescribed conditions is acquired by the position acquisition unit250and stored in the position data storage unit222, the analysis unit360may analyze the state of the axle device1A based on the vibration detection data acquired when the dump truck100travels at that position. The dump truck100often travels a determined route a plurality of times. It is highly possible that the travel state of the dump truck100is always constant at a certain position on the route. In such a case, even if the travel state detection device400does not always monitor the travel state of the dump truck100, when the dump truck100travels at that position, the condition satisfaction determination unit260can determine that the travel state of the dump truck100satisfies the prescribed conditions. That is, when the dump truck100travels on the determined route a plurality of times, if the travel state detection device400detects the travel state only once or a plurality of times at the beginning, then the analysis unit360can thereafter analyze the state of the axle device1A based on the vibration detection data acquired when the dump truck100travels at that position.

In the above-mentioned embodiment, at least a part of the functions of the control device200may be provided in the server500, or at least a part of the functions of the vibration analysis device300may be provided in the server500. Further, for example, the control device200may be mounted on the dump truck100, and the vibration analysis device300may be disposed outside the dump truck100.

The state detection system1000and the state detection method, which are described in the above-mentioned embodiment, can also be applied to the transmission device1B.

In the above-described embodiment, the dump truck100may be an unmanned dump truck that travels by remote control or autonomously travels. Further, when the dump truck100is an unmanned dump truck, the throttle opening (accelerator opening) of the throttle valve of the power source70is adjusted based on a remote operation signal or a control signal.

In the above-mentioned embodiment, the dump truck100is defined to be a live-axle dump truck. The dump truck100may be an articulated dump truck having a front vehicle body frame, a rear vehicle body frame, and a joint mechanism that couples the front body frame and the rear body frame to each other.

In the above-mentioned embodiment, the work vehicle100is defined to be a dump truck. The work vehicle100just needs to be a wheel-driven work vehicle, and may be a wheel loader for example.

REFERENCE SIGNS LIST