Tire state management system and work vehicle

Abstract

The present invention provides a tire state management system and a work vehicle capable of suppressing erroneous determination of a slow puncture, the erroneous determination being caused by a state of a work device.　A tire state management system or the like for managing a state of a tire 11 of a wheel loader 1 includes: an air pressure sensor 31 for detecting an air pressure of the tire 11; a cylinder pressure sensor 32 for detecting a cylinder pressure P of a lift arm cylinder 22; and a controller 5 for determining a slow puncture of the tire 11 on the basis of air pressures Pa, Pb detected by the air pressure sensor 31 and air pressures Pa, Pb detected by the air pressure sensor 31 when the cylinder pressure P detected by the cylinder pressure sensor 32 is less than a predetermined pressure threshold Pth.

Description

Tire condition management system and work vehicle

[0001] The present invention relates to a tire condition management system that manages the condition of tires of a work vehicle including a work device, and to the work vehicle.

[0002] Decreases in tire air pressure include abrupt decreases typified by normal punctures and bursts, and gradual decreases called slow punctures. In the case of the latter slow puncture, air inside the tire leaks slowly over time due to, for example, damage to a wheel or deterioration of an air valve, so it is difficult for an operator to notice that air inside the tire is leaking. If the operator continues to operate the vehicle without noticing a slow puncture, there is a risk that it will eventually lead to a burst. For this reason, various methods for determining slow punctures have been conventionally proposed.

[0003] For example, in Patent Document 1, as a method for determining a slow puncture, air pressure data of a plurality of tires mounted on a vehicle is acquired, and based on the acquired air pressure data, a first representative value relating to the air pressure of each tire in a first period and a second representative value relating to the air pressure of each tire in a second period longer than the first period are respectively calculated, and a degree of decrease of the first representative value relative to the second representative value is calculated for each tire. A method is disclosed in which, when the degree of decrease of one tire is equal to or greater than a first threshold value and the degree of decrease of another tire different from the one tire is less than the first threshold value, it is determined that there is a decrease in air pressure due to a slow puncture.

[0004] Japanese Patent No. 7405732

[0005] However, when the slow puncture determination method described in Patent Document 1 is applied to a work vehicle, the tire air pressure changes depending on the posture of the work device and the presence or absence of a load in the work device, so there is a possibility that this tire air pressure change is erroneously determined as a tire air pressure change caused by a slow puncture.

[0006] Therefore, an object of the present invention is to provide a tire condition management system and a work vehicle that can suppress erroneous determination of slow punctures caused by the state of a work device.

[0007] To achieve the above objective, the present invention provides a tire condition management system for managing the condition of the tires of a work vehicle having a work device attached to the front of the vehicle body, comprising: an air pressure detection device for detecting the air pressure of the tires; a cylinder pressure detection device for detecting the cylinder pressure, which is the pressure of a hydraulic cylinder that drives the work device; and a controller for determining a slow puncture in the tires based on the air pressure detected by the air pressure detection device when the cylinder pressure detected by the cylinder pressure detection device is less than a predetermined pressure threshold.

[0008] According to the present invention, it is possible to suppress misdiagnosis of slow punctures caused by the condition of the work equipment. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

[0009] This is an external side view showing an example configuration of a wheel loader according to an embodiment of the present invention. This is a functional block diagram showing the functions of the controller. This is a schematic diagram showing the wheel loader when the bucket is in a horizontal ground position. This is a schematic diagram showing the wheel loader when the working device is in a transport position and stationary. This is a schematic diagram showing the wheel loader when the working device is in a transport position and traveling. This is a schematic diagram showing the wheel loader in a jacked-up state. This is a flowchart showing the flow of processing performed by the controller.

[0010] <Overall Configuration of Wheel Loader 1> First, the overall configuration of the wheel loader 1 according to an embodiment of the present invention will be described with reference to Figure 1.

[0011] Figure 1 is an external side view showing one example of the configuration of a wheel loader 1 according to an embodiment of the present invention.

[0012] The wheel loader 1 is an articulated work vehicle that is steered by folding its body in the middle near its center. The front frame 1A, which is the front part of the vehicle body, and the rear frame 1B, which is the rear part of the vehicle body, are connected by a center joint 10 so as to be rotatable in the left-right direction, and the front frame 1A bends in the left-right direction relative to the rear frame 1B.

[0013] In the following explanation, the left-hand direction relative to the forward direction of the vehicle will be referred to as the "left direction," and the right-hand direction relative to the forward direction will be referred to as the "right direction."

[0014] The vehicle body is equipped with four tires 11. Two tires 11 are positioned as front tires 11A on the left and right sides of the front frame 1A, and the remaining two tires 11 are positioned as rear tires 11B on the left and right sides of the rear frame 1B. In Figure 1, only the front tires 11A and rear tires 11B located on the left side are shown.

[0015] Each tire 11 is fitted with an air pressure sensor 31, which serves as an air pressure detection device for detecting the air pressure in the tire 11. Each air pressure sensor 31 is powered by a built-in battery and includes a transmitter that wirelessly transmits the detected air pressure information at predetermined time intervals. The air pressure detected by each air pressure sensor 31 is output periodically and unilaterally to a controller 5 (described later) via wireless communication through the transmitter at predetermined time intervals, and is used to determine whether or not a slow puncture has occurred in each tire 11 (determination of slow puncture in each tire 11).

[0016] In the following, the air pressure sensor 31 that detects the air pressure of the front tire 11A (front air pressure Pa) may be referred to as "front air pressure sensor 31A," and the air pressure sensor 31 that detects the air pressure of the rear tire 11B (rear air pressure Pb) may be referred to as "rear air pressure sensor 31b." Note that in Figure 1, of the four air pressure sensors 31, only the front air pressure sensor 31A and the rear air pressure sensor 31b, which are located on the left side, are shown with dashed lines.

[0017] A hydraulically driven work device 2 is attached to the front of the front frame 1A for excavating work materials such as soil and minerals, and for loading the excavated work materials onto loading destinations such as dump trucks and hoppers.

[0018] The work device 2 includes a lift arm 21 that is rotatably mounted vertically to the front frame 1A, two lift arm cylinders 22 that act as hydraulic cylinders to drive the lift arm 21, a bucket 23 that is rotatably mounted vertically to the tip of the lift arm 21, a bucket cylinder 24 that acts as a hydraulic cylinder to drive the bucket 23, and a bell crank 25 that is rotatably connected to the lift arm 21 and forms a link mechanism between the bucket 23 and the bucket cylinder 24.

[0019] The two lift arm cylinders 22 are arranged side by side with a predetermined distance between them in the left-right direction of the vehicle body, and in Figure 1, only the lift arm cylinder 22 located on the left side is shown with a dashed line.

[0020] The lift arm 21 rotates upward relative to the front frame 1A when hydraulic fluid is supplied from a hydraulic pump to the bottom chamber of each lift arm cylinder 22, and when the hydraulic fluid is discharged from the rod chamber to the tank, the rods 220 extend. The lift arm 21 also rotates downward relative to the front frame 1A when hydraulic fluid is supplied from a hydraulic pump to the rod chamber of each lift arm cylinder 22, and when the hydraulic fluid is discharged from the bottom chamber to the tank, the rods 220 retract.

[0021] The cylinder pressure P, which is the pressure of the hydraulic fluid applied to each lift arm cylinder 22, is detected by a cylinder pressure sensor 32 (shown by a dashed line in Figure 1). This cylinder pressure sensor 32 is one embodiment of a cylinder pressure detection device that detects the cylinder pressure P of the hydraulic cylinders that drive the work device 2.

[0022] Specifically, the cylinder pressure sensor 32 detects the bottom pressure, which is the pressure applied to the bottom chamber of the lift arm cylinder 22, as the cylinder pressure P. Since the bottom pressure of the lift arm cylinder 22 changes depending on the magnitude of the load applied to the work device 2, the load state of the work device 2 can be determined based on the cylinder pressure P detected by the cylinder pressure sensor 32.

[0023] Furthermore, an angle sensor 33 is attached to the base end of the lift arm 21 (the pin portion connecting the lift arm 21 and the front frame 1A) as an angle detection device for detecting the vertical angle θ of the work device 2 relative to the vehicle body. Specifically, the angle θ detected by the angle sensor 33 is the rotation angle of the lift arm 21 relative to the front frame 1A. If the angle θ when the lift arm 21 is in a horizontal position is taken as 0°, then the angle θ when the lift arm 21 is rotated upward from the horizontal position will be a positive value, and the angle θ when the lift arm 21 is rotated downward from the horizontal position will be a negative value.

[0024] The bucket 23 rotates vertically relative to the lift arm 21 as hydraulic fluid flows in and out of the bucket cylinder 24, causing the rod 240 to extend and retract. This allows the bucket 23 to scoop up and discharge (excavate and release) workpieces such as soil and minerals.

[0025] Furthermore, the bucket 23 can be replaced with various attachments such as blades, and the wheel loader 1 can perform various tasks in addition to cargo handling using the bucket 23, such as snow removal and soil pushing.

[0026] The rear frame 1B is provided with a driver's cab 12 where the operator sits, a machine room 13 that houses various equipment necessary for driving the wheel loader 1, and a counterweight 14 that maintains balance with the work device 2 to prevent the vehicle body from tilting. In the rear frame 1B, the driver's cab 12 is located at the front, the counterweight 14 is located at the rear, and the machine room 13 is located between the driver's cab 12 and the counterweight 14.

[0027] In this embodiment, the driver's cab 12 is equipped with a monitor 4 (see Figure 2) which serves as a notification device to notify that the tire 11 is in a slow-puncture state. Note that the notification device does not necessarily have to be a monitor 4; it could be, for example, a buzzer. Furthermore, the notification device does not necessarily have to be located in the driver's cab 12; it could be located elsewhere, for example, in the control center that manages the wheel loader 1, or it could be located in both the wheel loader 1 and the control center.

[0028] [Configuration of Controller 5] Next, the configuration of Controller 5 will be explained with reference to Figures 2 to 4.

[0029] Figure 2 is a functional block diagram showing the functions of the controller 5.

[0030] Controller 5 is configured with a CPU, RAM, ROM, HDD, input interface, and output interface all connected to each other via a bus. Various sensors, such as each front tire pressure sensor 31A, each rear tire pressure sensor 31B, cylinder pressure sensor 32, and angle sensor 33, are connected to the input interface, and the monitor 4 is connected to the output interface.

[0031] As mentioned above, each air pressure sensor 31 (each front air pressure sensor 31A and each rear air pressure sensor 31B) transmits air pressure information (air pressure data) to the controller 5 via wireless communication; therefore, the controller 5 includes a receiver for wireless reception.

[0032] The tire condition management system for managing the condition of each tire 11 of the wheel loader 1 includes a controller 5, each front air pressure sensor 31A, each rear air pressure sensor 31B, a cylinder pressure sensor 32, an angle sensor 33, and a monitor 4.

[0033] In this hardware configuration, the CPU reads the control program (software) stored on a recording medium such as ROM, HDD, or optical disc, expands it onto RAM, and executes the expanded control program. The control program and hardware then work together to realize the functions of the controller 5.

[0034] In this embodiment, the configuration of the controller 5 is described as a combination of software and hardware, but it is not limited to this, and may also be configured using an integrated circuit that realizes the functions of the control program executed on the wheel loader 1.

[0035] The controller 5 includes a data acquisition unit 51, a cylinder pressure determination unit 52, a jack-up determination unit 53, an air pressure selection unit 54, a slow puncture determination unit 55, a storage unit 56, and a notification command unit 57.

[0036] The data acquisition unit 51 acquires the front air pressure Pa detected by each front air pressure sensor 31A, the rear air pressure Pb detected by each rear air pressure sensor 31B, the cylinder pressure P detected by the cylinder pressure sensor 32, and the angle θ detected by the angle sensor 33.

[0037] The cylinder pressure determination unit 52 determines whether the cylinder pressure P acquired by the data acquisition unit 51 is less than a predetermined pressure threshold Pth. The "predetermined pressure threshold Pth" is a value based on the cylinder pressure of the lift arm cylinder 22 when the work device 2 is in a low-load state, and is set to, for example, about 5 MPa. In other words, the cylinder pressure determination unit 52 determines whether the work device 2 is in a low-load state (whether it is in a low-load state or a high-load state).

[0038] Here, the wheel loader 1 when the working device 2 is in a low-load state will be described with reference to Figures 3A to 3C.

[0039] Figure 3A is a schematic diagram showing the wheel loader 1 when the bucket 23 is in a horizontal ground position. Figure 3B is a schematic diagram showing the wheel loader 1 when the working device 2 is in a transport position and stationary. Figure 3C is a schematic diagram showing the wheel loader 1 when the working device 2 is in a transport position and traveling.

[0040] First, as shown in Figure 3A, when the vehicle is stationary (vehicle speed = 0 km / h) and the bucket 23 is empty and in a horizontal ground position with the bottom surface of the bucket 23 in contact with the ground, the working device 2 is in a low-load state.

[0041] Next, as shown in FIG. 3B, when the vehicle is stopped (vehicle speed = 0 km / h) and the working device 2 is in the transport posture (the lift arm 21 is in a horizontal posture; angle θ = 0°), the working device 2 is in a low-load state.

[0042] Then, as shown in FIG. 3C, when the vehicle is traveling (vehicle speed > 0 km / h) and the working device 2 is in the transport posture (the lift arm 21 is in a horizontal posture; angle θ = 0°), the working device 2 is in a low-load state.

[0043] In the states shown in these FIGS. 3A to 3C, that is, when the working device 2 is in a low-load state, all four tires 11 (two front tires 11A and two rear tires 11B) are in contact (grounded) with the ground, and only the self-weight of the vehicle body and the self-weight of the working device 2 act as pressure.

[0044] Returning to FIG. 2, when the cylinder pressure determination unit 52 determines that the cylinder pressure P is equal to or higher than the predetermined pressure threshold Pth (P≧Pth), the jack-up determination unit 53 determines whether the angle θ acquired by the data acquisition unit 51 is less than the predetermined angle threshold θth. The "predetermined angle threshold θth" is a value based on the angle of the working device 2 (the rotation angle of the lift arm 21) when the wheel loader 1 is in the jack-up state, and is set to, for example, about -30°. That is, the jack-up determination unit 53 determines whether or not the wheel loader 1 is in the jack-up state.

[0045] Here, the wheel loader 1 in the jack-up state will be described with reference to FIG. 4.

[0046] FIG. 4 is a schematic diagram showing the wheel loader 1 in the jack-up state.

[0047] In the jack-up state, the wheel loader 1 is stopped (vehicle speed = 0 km / h), the bucket 23 is empty and the toe of the bucket 23 is in contact with the ground (the working device 2 is empty and in a high-load state), and a load is applied to the toe of the bucket 23, so that the two front tires 11A are lifted off the ground. At this time, pressure lower than the pressure when the working device 2 is in the low-load state acts on the two front tires 11A.

[0048] That is, the jack-up state is a state where the weight of the vehicle body is supported by the work implement 2 and the two rear tires 11B, instead of the state where the weight of the vehicle body is supported by the two front tires 11A and the two rear tires 11B. Therefore, although the support on the front side of the vehicle body that supports the weight of the vehicle body differs, the load on the two rear tires 11B does not differ significantly from that in the low load state.

[0049] Then, considering the above-mentioned specifications of the air pressure sensors 31 (the detection is performed unilaterally at predetermined time intervals and output to the controller 5) and the fact that the air pressures Pa and Pb detected by each air pressure sensor 31 are valid data only when in the low load state, if the detection timing of each air pressure sensor 31 does not match the timing of the low load state, there is a possibility that the controller 5 cannot acquire valid data related to the air pressures Pa and Pb throughout the day. Accordingly, the controller 5 allows recording of the air pressure Pb of each rear tire 11B in the jack-up state so as to record as much valid data related to the air pressures Pa and Pb as possible.

[0050] Returning to FIG. 2, when the cylinder pressure determination unit 52 determines that the cylinder pressure P is less than a predetermined pressure threshold Pth (P<Pth), that is, when the work implement 2 is in a low load state, the air pressure selection unit 54 selects all of the four air pressures Pa and Pb acquired by the data acquisition unit 51 as slow leak determination values, and stores them in the storage unit 56.

[0051] Further, when the cylinder pressure determination unit 52 determines that the cylinder pressure P is equal to or higher than the predetermined pressure threshold Pth (P≧Pth), and the jack-up determination unit 53 determines that the angle θ is less than a predetermined angle threshold θth (θ<θth), that is, when the jack-up condition is satisfied, the air pressure selection unit 54 selects only the two rear air pressures Pb among the four air pressures Pa and Pb acquired by the data acquisition unit 51 as slow leak determination values, and stores them in the storage unit 56.

[0052] In this case, as mentioned above, the pressure acting on the front tire 11A is lower than under normal conditions (when the work device 2 is under low load), and there is a risk of misjudging that the front tire 11A is in a normal state but is actually experiencing a slow puncture. Therefore, the air pressure selection unit 54 does not select the two front air pressures Pa as slow puncture detection values.

[0053] Furthermore, if the cylinder pressure determination unit 52 determines that the cylinder pressure P is equal to or greater than a predetermined pressure threshold Pth (P ≥ Pth), and the jack-up determination unit 53 determines that the angle θ is equal to or greater than a predetermined angle threshold θth (θ ≥ θth), the air pressure selection unit 54 will not select any of the four air pressures Pa and Pb acquired by the data acquisition unit 51 as slow puncture determination values.

[0054] This is because the wheel loader 1 is not in a jacked-up state, but simply has a load in the bucket 23, meaning the working device 2 is not empty and is under a high load. As a result, the pressure acting on all four tires 11 becomes higher than normal (when the working device 2 is under a low load), and there is a risk that the system may mistakenly determine that the condition is normal even though a slow puncture is occurring in the tires 11.

[0055] Furthermore, if the air pressure of each tire 11 under high load conditions is used to determine whether a slow puncture has occurred, a change in air pressure (decrease in air pressure) from the air pressure of each tire 11 under high load conditions (loaded condition) to the air pressure of each tire 11 under low load conditions (unloaded condition) may lead to a false determination that a slow puncture has occurred even though one has not.

[0056] In other words, if the air pressure of each tire 11 under high load conditions is used as the standard, there is a risk that a slow puncture may be mistakenly determined to have occurred even if the load condition has simply decreased. Therefore, when the work device 2 is under high load conditions, such as when there is a load in the bucket 23, all four air pressures Pa and Pb are not selected as slow puncture detection values.

[0057] The slow puncture detection unit 55 determines whether a tire has a slow puncture based on the slow puncture detection value (air pressure) selected by the air pressure selection unit 54 and stored in the memory unit 56. Specifically, the slow puncture detection unit 55 determines that the tire 11 in question has a slow puncture if the percentage decrease in air pressure used as the slow puncture detection value is greater than a predetermined percentage decrease.

[0058] The memory unit 56 stores not only the slow puncture detection value, but also a predetermined pressure threshold Pth and a predetermined angle threshold θth.

[0059] The notification command unit 57 outputs a notification signal to the monitor 4 when the slow puncture detection unit 55 determines that the tire 11 in question is in a slow puncture state.

[0060] In this embodiment, the controller 5 determines whether a slow puncture has occurred and issues a notification command to the monitor 4. However, this is not limited to this. For example, an on-board controller mounted on the wheel loader 1 may decide whether or not to select the air pressure as the slow puncture determination value to be used for determining the slow puncture, and the subsequent slow puncture determination and notification command may be performed by a server installed in the management headquarters that manages the wheel loader 1.

[0061] In this case, the wheel loader 1 is equipped with a transceiver for communicating with an external server. Data transmission and reception between the wheel loader 1 and the server is performed at a regular frequency, such as once a day, and is limited to valid data rather than all data in order to reduce the amount of data.

[0062] [Processing performed by Controller 5] Next, the flow of processing performed within Controller 5 will be explained with reference to Figure 5.

[0063] Figure 5 is a flowchart showing the processing flow executed by controller 5.

[0064] In the controller 5, first, the data acquisition unit 51 acquires the front air pressure Pa detected by each front air pressure sensor 31A, the rear air pressure Pb detected by each rear air pressure sensor 31B, the cylinder pressure P detected by the cylinder pressure sensor 32, and the angle θ detected by the angle sensor 33 (step S501).

[0065] Next, the cylinder pressure determination unit 52 determines whether the cylinder pressure P obtained in step S501 is less than a predetermined pressure threshold Pth (step S502).

[0066] If it is determined in step S502 that the cylinder pressure P is less than a predetermined pressure threshold Pth (P < Pth) (step S502 / YES), the air pressure selection unit 54 selects all four air pressures Pa and Pb obtained in step S501 as slow puncture determination values ​​(step S503).

[0067] On the other hand, if it is determined in step S502 that the cylinder pressure P is equal to or greater than a predetermined pressure threshold Pth (P ≥ Pth) (step S502 / NO), the jack-up determination unit 53 determines whether the angle θ obtained in step S501 is less than a predetermined angle threshold θth (step S504).

[0068] If it is determined in step S504 that the angle θ is less than a predetermined angle threshold θth (θ < θth) (step S504 / YES), the air pressure selection unit 54 selects only the two rear air pressures Pb obtained in step S501 as the slow puncture determination values ​​(step S505).

[0069] On the other hand, if it is determined in step S504 that the angle θ is greater than or equal to a predetermined angle threshold θth (θ≧θth) (step S504 / NO), the processing in the controller 5 ends.

[0070] Once the processes in step S503 and step S505 are completed, the slow puncture determination unit 55 determines whether or not the tire 11 in question is in a slow puncture state (step S506).

[0071] If it is determined in step S506 that the target tire 11 is in a slow-puncture state, the notification command unit 57 outputs a notification signal to the monitor 4 to notify that the target tire 11 is in a slow-puncture state (step S507), and the processing in the controller 5 ends.

[0072] On the other hand, if it is determined in step S506 that the tire 11 in question is not in a slow-puncture state, the process returns to step S501 and is repeated.

[0073] Thus, when the work device 2 is not empty but under a high load, such as when a load is simply placed in the bucket 23, the controller 5 does not use the air pressures Pa and Pb of the four tires 11 as slow puncture detection values. This prevents the controller from mistakenly determining that a slow puncture has occurred in one of the tires 11, when in fact it is in a normal state.

[0074] Furthermore, when the wheel loader 1 is in a jacked-up state, the controller 5 does not use the air pressure Pa of the two front tires 11A, which are subjected to a lower pressure than when the work device 2 is in a low-load state, as the slow puncture detection value. Instead, it uses only the air pressure Pb of the two rear tires 11B, which are not significantly different from the pressure in a low-load state, as the slow puncture detection value. This allows the controller 5 to efficiently acquire only valid air pressure data and determine if a slow puncture has occurred.

[0075] In other words, the controller 5 determines whether or not the air pressures Pa and Pb detected by each air pressure sensor 31 should be used as slow puncture detection values ​​based on the state of the work device 2, and then makes a slow puncture determination. As a result, erroneous determinations of slow punctures caused by the state of the work device 2 are suppressed, and accurate determination results can be obtained efficiently.

[0076] Embodiments of the present invention have been described above. It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, in the above embodiments, a wheel loader 1 was used as an example of a work vehicle, but the invention is not limited to this, and the present invention can be applied to any work vehicle other than a wheel loader 1, as long as it is equipped with a work device 2.

[0077] 1: Wheel loader (work vehicle) 1A: Front frame (body) 1B: Rear frame (body) 2: Work equipment 4: Monitor (notification device) 5: Controller 11, 11A: Front tire, tire 11, 11B: Rear tire, tire 22: Lift arm cylinder (hydraulic cylinder) 24: Bucket cylinder (hydraulic cylinder) 31, 31A: Front air pressure sensor, air pressure sensor (front air pressure detection device, air pressure detection device) 31, 31B: Rear air pressure sensor, air pressure sensor (rear air pressure detection device, air pressure detection device) 32: Cylinder pressure sensor (cylinder pressure detection device) 33: Angle sensor (angle detection device) P: Cylinder pressure Pa: Front air pressure, air pressure Pb: Rear air pressure, air pressure Pth: Determined pressure threshold θ: Angle θth: Determined angle threshold

Claims

1. A tire condition management system for managing the condition of the tires of a work vehicle having a work device attached to the front of the vehicle body, comprising: an air pressure detection device for detecting the air pressure of the tire; a cylinder pressure detection device for detecting the cylinder pressure, which is the pressure of a hydraulic cylinder that drives the work device; and a controller for determining a slow puncture in the tire based on the air pressure detected by the air pressure detection device when the cylinder pressure detected by the cylinder pressure detection device is less than a predetermined pressure threshold.

2. A tire condition management system according to claim 1, further comprising an angle detection device for detecting the vertical angle of the work device with respect to the vehicle body, wherein the air pressure detection device includes a front air pressure detection device for detecting the front air pressure which is the air pressure of the front tire mounted on the front side of the work vehicle, and a rear air pressure detection device for detecting the rear air pressure which is the air pressure of the rear tire mounted on the rear side of the work vehicle, wherein the controller determines a slow puncture of the front tire based on the front air pressure detected by the front air pressure detection device when the cylinder pressure detected by the cylinder pressure detection device is less than the pressure threshold, and determines a slow puncture of the rear tire based on the rear air pressure detected by the rear air pressure detection device when the cylinder pressure detected by the cylinder pressure detection device is less than the pressure threshold, and the rear air pressure detected by the rear air pressure detection device when the jack-up condition is met, which is that the cylinder pressure detected by the cylinder pressure detection device is greater than or equal to a predetermined pressure threshold and the angle detected by the angle detection device is less than a predetermined angle threshold.

3. A tire condition management system according to claim 1, wherein the air pressure detection device includes a transmitter attached to the tire and wirelessly transmits the detected air pressure information at predetermined time intervals, and the controller includes a receiver that wirelessly receives the air pressure information transmitted from the transmitter.

4. A tire condition management system according to claim 1, further comprising a notification device for notifying that the tire is in a slow-puncture state, wherein the controller outputs a notification signal to the notification device for notifying that the tire is in a slow-puncture state when the decrease rate of the air pressure detected by the air pressure detection device when the cylinder pressure detected by the cylinder pressure detection device is less than a predetermined pressure threshold is greater than a predetermined decrease rate.

5. A work vehicle comprising: a vehicle body; tires provided on the vehicle body; a work device attached to the front of the vehicle body; a hydraulic cylinder for driving the work device; an air pressure detection device for detecting the air pressure of the tires; and a cylinder pressure detection device for detecting the cylinder pressure, which is the pressure of the hydraulic cylinder, wherein the work vehicle has an on-board controller that selects the air pressure detected by the air pressure detection device as a determination value used to determine whether the tire has a slow puncture when the cylinder pressure detected by the cylinder pressure detection device is less than a predetermined pressure threshold.

Images