Work vehicle

Abstract

To provide a work vehicle which can improve the performance of loading work.SOLUTION: A work vehicle includes: a vehicle body: a work device; a motor; a variable-capacity hydraulic pump driven by the motor and supplying pressure oil; a hydraulic actuator for driving the work device with the pressure oil supplied from the hydraulic pump; a driving force transmission device for transmitting the power of the motor to the vehicle body as a travel driving force; a brake device for braking the traveling of the vehicle body; a brake state detector for detecting an operational state of the brake device; and a control device. The control device determines whether or not the traveling of the vehicle body is in a stopped state or a state of being stopped based on a detection signal from the brake state detector, and performs control to increase a capacity of the hydraulic pump when it is determined that the traveling of the vehicle body is in the stopped state or the state of being stopped and transmission of the travel driving force to the vehicle body is blocked or restricted by the drive force transmission device.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a work vehicle. [Background technology]

[0002] A control technique for accelerating the lift arm speed during loading operations onto a dump truck is known for work vehicles such as wheel loaders. For example, Patent Document 1 (JP-A-2005-109523) describes an industrial vehicle including a priority valve that can be switched between a normal position where hydraulic oil (pressurized oil) from an accessory pump is directed to an auxiliary device and a lift acceleration position where hydraulic oil is directed to a lift arm cylinder (boom cylinder), and a control device that controls the priority valve. In Patent Document 1, the control device determines a threshold value that is lower than the requested engine speed when a lift operation is performed to raise the lift arm, and maintains the priority valve in the normal position when the actual engine speed is below the threshold value, and switches the priority valve to the lift acceleration position when the actual engine speed exceeds the threshold value (see abstract). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-158099 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in Patent Document 1, the priority valve switches to the lift acceleration position when the actual engine speed exceeds the threshold, so the lift arm lift speed is limited until the actual engine speed exceeds the threshold, which poses a problem of reduced performance in loading and unloading operations.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a work vehicle that can improve the performance of cargo handling operations by increasing the speed of the lift arms in a timely manner during loading operations. [Means for solving the problem]

[0006] In order to achieve the above object, a first aspect of the present invention is a work vehicle comprising a vehicle body, a working device provided at the front of the vehicle body, a prime mover mounted on the vehicle body, a variable displacement hydraulic pump driven by the prime mover and supplying pressurized oil, a hydraulic actuator that drives the working device with pressurized oil supplied from the hydraulic pump, a driving force transmission device that transmits the power of the prime mover to the vehicle body as a driving force for traveling, a brake device that brakes the traveling of the vehicle body, a brake state detector that detects the operating state of the brake device, and a control device, wherein the control device determines whether the traveling of the vehicle body is in a stopped state or a state in which the traveling of the vehicle body is about to stop based on a detection signal from the brake state detector, and when it is determined that the traveling of the vehicle body is in a stopped state or a state in which the traveling of the vehicle body is about to stop and the transmission of the driving force for traveling to the vehicle body is interrupted or restricted by the driving force transmission device, performs control to increase the capacity of the hydraulic pump. [Effects of the Invention]

[0007] According to the present invention, the lift arm speed can be increased in a timely manner during loading operations, improving the performance of the loading operation. Note that other problems, configurations, and effects will become clear from the following description of the embodiments. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a side view of a wheel loader according to a first embodiment of the present invention. [Figure 2] 1 is a system configuration diagram of a wheel loader according to a first embodiment. [Figure 3] 10 is a flowchart showing the procedure of a control process of the main controller. [Figure 4] FIG. 10 is an explanatory diagram comparing the timing of lift acceleration between the present invention and the prior art. [Figure 5]FIG. 10 is a system configuration diagram of a wheel loader according to a second embodiment. [Figure 6] 10 is a flowchart showing the procedure of control processing of a main controller in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, various embodiments of a wheel loader, which is an example of a work vehicle according to the present invention, will be described with reference to the drawings.

[0010] (First embodiment) FIG. 1 is a side view of a wheel loader 100 according to a first embodiment of the present invention.

[0011] As shown in Fig. 1, the wheel loader 100 comprises a front vehicle body 110 having a lift arm 111, a bucket 112, a pair of tires (front wheels) 9, etc., and a rear vehicle body 120 having a driver's cab 121, an engine compartment 122, and a pair of tires (rear wheels) 10, etc. An engine 190 serving as a prime mover is mounted in the engine compartment 122, and a counterweight 123 is attached to the rear of the rear vehicle body 120. The front vehicle body 110, which is a front frame, and the rear vehicle body 120, which is a rear frame, are connected by a center pin 101 so that they can rotate freely relative to each other, and the front vehicle body 110 bends left and right relative to the rear vehicle body 120 due to the extension and contraction of a steering cylinder 116, which is a hydraulic actuator.

[0012] The lift arm 111 rotates (elevates) in the vertical direction by driving a pair of lift arm cylinders 117, and the bucket 112 rotates (tilts or dumps) in the vertical direction by driving a bucket cylinder 115. A link mechanism including a bell crank 113 is interposed between the bucket cylinder 115 and the bucket 112, and the bucket cylinder 115 rotates the bucket 112 via this link mechanism. The lift arm 111, bucket 112, pair of lift arm cylinders 117, bucket cylinder 115, bell crank 113, etc. constitute a working device 114 for carrying out cargo handling work.

[0013] The cab 121 mounted at the front of the rear body 120 is equipped with a driver's seat where an operator sits, a cargo handling operation lever 17 for operating the work equipment 114, a steering wheel for controlling the steering angle of the wheel loader 100, a forward / reverse command lever 4, an accelerator pedal 5, a brake pedal 6, etc. The cab 121 also has a main controller 3 for controlling the overall operation of the wheel loader 100 (see Figure 2).

[0014] Next, a description will be given of the drive system of the wheel loader 100. Figure 2 is a system configuration diagram showing an example of the configuration of the drive system of the wheel loader 100.

[0015] The wheel loader 100 has the traveling of the vehicle bodies 110, 120 controlled by a torque converter type traveling drive system, and as shown in FIG. 2, is equipped with an engine 190, an engine controller 1 that controls the engine 190, a torque converter 7 (hereinafter referred to as "torque converter 7") connected to the output shaft of the engine 190, a transmission 8 connected to the output shaft of the torque converter 7, and a main controller 3 that controls each device including the engine controller 1, torque converter 7, and transmission 8.

[0016] The engine 190 starts when the operator turns on the ignition switch provided in the cab 121, and then rotates when the operator depresses the accelerator pedal 5. The rotation speed NE of the engine 190 (hereinafter simply referred to as "engine rotation speed NE") is proportional to the depression amount of the accelerator pedal 5, and increases as the depression amount of the accelerator pedal 5 increases.

[0017] The engine speed NE is detected by an actual engine speed sensor 18 attached to the engine 190. The depression amount of the accelerator pedal 5 is detected by a depression amount sensor (not shown) attached to the accelerator pedal 5. The engine speed NE detected by the actual engine speed sensor 18 and the depression amount of the accelerator pedal 5 detected by the depression amount sensor are each input to the main controller 3.

[0018] The engine controller 1 is connected to the main controller 3 via a CAN (Controller Area Network) and controls the engine speed NE based on a command signal (a command signal related to a target speed indicated by the accelerator pedal 5) output from the main controller 3.

[0019] In this embodiment, the main controller 3 that controls the entire drive system of the wheel loader 100 and the engine controller 1 that controls the engine 190 are provided separately, but this is not limited to this, and the entire drive system of the wheel loader 100 and the engine 190 may be controlled by one controller (main controller 3).

[0020] The torque converter 7 is a fluid clutch made up of an impeller, a turbine, and a stator. When the input shaft of the torque converter 7 rotates due to the driving force of the engine 190, the output shaft of the torque converter 7 rotates via torque converter oil as a working fluid, and the driving force of the engine 190 is transmitted to the transmission 8.

[0021] The torque converter 7 has a function of increasing the output torque relative to the input torque, that is, a function of making the torque ratio (= output torque / input torque) equal to or greater than 1. This torque ratio decreases as the torque converter speed ratio (= output shaft rotation speed / input shaft rotation speed), which is the ratio of the rotation speed of the input shaft of the torque converter 7 to the rotation speed of the output shaft, increases. As a result, the rotational force of the engine 190 is transmitted to the transmission 8 after its rotational speed is changed via the torque converter 7.

[0022] The transmission 8 is an automatic transmission composed of a clutch mechanism having multiple clutches and a gear mechanism having multiple speed-change gears, which switches the vehicle body between forward and reverse motion and changes the rotational speed of the output shaft of the torque converter 7.

[0023] The rotational force changed in speed by the transmission 8 is transmitted to tires 10 via an axle device 9, thereby causing the wheel loader 100 to travel.

[0024] Furthermore, when the wheel loader 100 stops or decelerates, the clutch mechanism of the transmission 8 is controlled according to the amount of depression (braking force) of the brake pedal 6 applied by the operator, thereby cutting off the transmission of driving force to the tires 10. The axle device 9 is provided with a brake pressure sensor 19 that detects brake pressure. The brake pressure detected by the brake pressure sensor 19 is input to the main controller 3.

[0025] The transmission 8 further includes a clutch disengagement mechanism 21. The clutch disengagement mechanism 21 is a mechanism that cuts off or limits the driving force transmitted from the engine 190, and when the clutch disengagement mechanism 21 is activated, the driving force from the engine 190 is not transmitted to the axle device 9. The main controller 3 determines whether to activate the clutch disengagement mechanism 21 based on the value of the brake pressure input from the brake pressure sensor 19. Specifically, the main controller 3 determines whether the brake pressure is below a threshold value. If the brake pressure is below the threshold value, the main controller 3 outputs a command signal to the transmission control unit 20 to activate the clutch disengagement mechanism 21.

[0026] Here, the threshold value is a value that can detect that the brake pedal 6 is depressed, and is a preset value.

[0027] When a command signal is input from the main controller 3, the transmission control unit 20 activates the clutch disengagement mechanism 21 to disengage the clutch (release the clutch). In other words, it cuts off the transmission of driving force between the torque converter 7 and the axle device 9. The control processing procedures by the main controller 3 and the transmission control unit 20 will be described later.

[0028] Switching between forward and reverse travel of the wheel loader 100 is performed by operating a forward / reverse command lever 4, which serves as a forward / reverse command means provided inside the driver's cab 121. As shown in Fig. 2, the forward / reverse command lever 4 switches between a forward position F, which causes the vehicle body to travel forward, a reverse position R, which causes the vehicle body to travel backward, and a neutral position N, which causes the vehicle body to stop, to command the traveling direction of the vehicle body.

[0029] When the operator operates the forward / reverse command lever 4, the forward / reverse command lever 4 outputs a command signal relating to the traveling direction of the vehicle body to the main controller 3. The main controller 3 controls the clutch mechanism of the transmission 8 based on the input command signal.

[0030] Specifically, when the forward / reverse command lever 4 is switched to the forward position F, the main controller 3 issues a command to the clutch mechanism of the transmission 8 via the transmission control unit 20 to engage the forward clutch.

[0031] On the other hand, when the forward / reverse command lever 4 is switched to the reverse position R, the main controller 3 issues a command to the clutch mechanism of the transmission 8 via the transmission control unit 20 to engage the reverse clutch.

[0032] Furthermore, when the forward / reverse command lever 4 is switched to the neutral position N, the main controller 3 issues a command to the clutch mechanism of the transmission 8 via the transmission control unit 20 to release (disengage) each of the forward clutch and the reverse clutch.

[0033] Furthermore, in addition to the vehicle body travel drive system, the wheel loader 100 is also equipped with a load handling drive system for driving the work implement 114. The load handling drive system is composed of a variable displacement load handling hydraulic pump 11 that is driven by the engine 190 and supplies pressure oil to each of the two lift arm cylinders 117 and the bucket cylinder 115, and a control valve 13 that is provided between the load handling hydraulic pump 11 and the two lift arm cylinders 117, and the bucket cylinder 115. Note that the type of the load handling hydraulic pump 11 is not important as long as it is a variable displacement type. For example, any type of variable displacement pump, such as a swash plate type or an bent axis type, can be used as the load handling hydraulic pump 11.

[0034] The control valve 13 is actuated by operation of the cargo handling operation lever 17 to control the flow (flow rate and direction) of pressurized oil supplied from the cargo handling hydraulic pump 11 to the lift arm cylinder 117 and bucket cylinder 115. Although only one control valve 13 is shown in Figure 2, in reality, two control valves are provided between the cargo handling hydraulic pump 11 and the lift arm cylinder 117, and between the cargo handling hydraulic pump 11 and the bucket cylinder 115.

[0035] Furthermore, the wheel loader 100 is equipped with an accessory drive system for driving an accessory fan 24. The accessory drive system is made up of an accessory pump 12 driven by the engine 190, a priority valve 14, a fan drive system 22, and a fan motor 23 which is a hydraulic motor. The engine 190 not only transmits driving force to the axle unit 9 which is the traveling drive system, but also serves as a drive source for supplying pressurized oil to the cargo drive system and the accessory drive system.

[0036] When the engine 190 is driven, the accessory pump 12 supplies pressurized oil to the fan motor 23. A priority valve 14 is provided in a flow path between the accessory pump 12 and the fan motor 23. The priority valve 14 is switchable between a normal position in which pressurized oil flows to the accessory pump 12 and a confluence position in which the priority valve 14 blocks the flow of pressurized oil to the accessory pump 12 and allows the pressurized oil to flow to the control valve 13. When the priority valve 14 is switched to the normal position, pressurized oil is supplied from the accessory pump 12 to the fan motor 23. On the other hand, when the priority valve 14 is switched to the confluence position, pressurized oil supplied from the accessory pump 12 is supplied to each of the two lift arm cylinders 117 and the bucket cylinder 115 via the control valve 13.

[0037] In other words, by switching the priority valve 14 to the junction position, the amount of pressure oil supplied to the cargo handling drive system increases, and the operating speed of the two lift arm cylinders 117 and the bucket cylinder 115 (load handling actuators) can be increased. Hereinafter, the increase in the operating speed of the cargo handling actuators may be referred to as "lift acceleration." The switching operation of the priority valve 14 is controlled by the main controller 3.

[0038] Next, a description will be given of the control processing procedure by the main controller 3, specifically, the procedure for controlling the operation of the clutch cut mechanism 21 and the priority valve 14. Figure 3 is a flowchart showing the control processing procedure for the clutch cut mechanism 21 and the priority valve 14.

[0039] The main controller 3 is configured, for example, by connecting a CPU, RAM, ROM, HDD, input I / F, and output I / F via a bus. In such a hardware configuration, the CPU reads a control program (software) stored in a recording medium such as a ROM, HDD, or optical disk, expands it on RAM, and executes the expanded control program, whereby the control program and hardware work together to realize the functions of the main controller 3.

[0040] As shown in FIG. 3, the main controller 3 determines whether the vehicle body is stopped (S10). Specifically, the main controller 3 determines whether the brake pressure detected by the brake pressure sensor 19 is less than a threshold value. If the brake pressure is less than the threshold value, the main controller 3 determines that the vehicle body is stopped. Note that by appropriately setting the threshold value, it is also possible to determine in S10 whether the vehicle body is in the process of stopping. Then, if it is determined that the vehicle body is in the stopped state (or is in the process of stopping) (S10 / YES), the main controller 3 determines whether the clutch disengagement mechanism 21 is operating (S20). Note that, as described above, if the brake pressure detected by the brake pressure sensor 19 is less than the threshold value, the clutch disengagement mechanism 21 is operated to release the connection between the power of the engine 190 and the axle device 9.

[0041] Then, when the clutch disengagement mechanism 21 is activated (S20 / YES), the main controller 3 increases the tilting of the cargo handling hydraulic pump 11 (increases the capacity) and advances the lift acceleration operation timing more quickly than usual (S30). That is, the main controller 3 switches the priority valve 14 to the junction position to supply at least a portion (or all) of the pressure oil from the accessory pump 12 for auxiliary equipment to the lift arm cylinder 117 and the bucket cylinder 115 via the control valve 13. Note that in this embodiment, in S30, the main controller 3 simultaneously increases the tilting of the cargo handling hydraulic pump 11 and switches the priority valve 14 to the junction position, but these do not necessarily have to be simultaneous.

[0042] FIG. 4 compares the timing of opening the priority valve 14 between the present invention and the prior art. As shown in FIG. 4, in the prior art, it was necessary to wait until the engine speed reached speed N2, which is close to the high speed range, before opening the priority valve 14 to accelerate the lift. In contrast, in the present invention, when the brake pressure drops and the clutch disengagement mechanism 21 is activated (i.e., the transmission of the driving force from the engine 190 to the axle unit 9 is cut off or limited), the tilt of the load handling hydraulic pump 11 is immediately increased, and the priority valve 14 is switched to the merge position to supply pressure oil from the accessory pump 12 to the lift arm cylinder 117 and the bucket cylinder 115. Therefore, it is possible to accelerate the lift when the engine speed is at speed N1, which is in the low speed range (idling state).

[0043] When the operator releases the brake pedal 6, the brake pressure increases and exceeds the threshold value. Then, the main controller 3 deactivates the clutch disengagement mechanism 21 (S40). That is, a state is established in which the engine 190 can transmit the driving force for traveling to the axle device 9. If the clutch disengagement mechanism 21 is deactivated (S40 / YES), the main controller 3 returns the tilt of the cargo handling hydraulic pump 11 to normal and switches the priority valve 14 to the normal position, thereby enabling the supply of pressurized oil from the accessory pump 12 for auxiliary machinery to the fan motor 23 (S50).

[0044] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0045] The wheel loader 100 (work vehicle) is equipped with an engine 190 (prime mover), a front body 110 and a rear body 120 (body), a working implement 114, a lift arm cylinder 117 and a bucket cylinder 115 (hydraulic actuators), a cargo handling hydraulic pump (variable displacement hydraulic pump) 11, a brake pedal 6 (brake device), a brake pressure sensor 19 (brake state detector), and a main controller 3 (control device).

[0046] The main controller 3 determines whether the brake pressure from the brake pressure sensor 19 is below a threshold value, and if the brake pressure is below the threshold value, determines that the wheel loader 100 is in a stopped state or is in the process of stopping (in the following explanation, a state in which the wheel loader 100 is in the process of stopping is also referred to as a stopped state). Then, the main controller 3 determines that the wheel loader 100 is in a stopped state, and activates the clutch disengagement mechanism 21 via the transmission control unit 20, and when a signal to disengage the clutch is input, that is, when the transmission of the travel driving force from the engine 190 to the axle device 9 is cut off or restricted, the main controller 3 controls the tilt of the cargo handling hydraulic pump 11 to increase.

[0047] By doing this, while the wheel loader 100 is stopped from traveling, the flow rate of pressurized oil supplied from the cargo handling hydraulic pump 11 to the lift arm cylinder 117 and bucket cylinder 115 increases, and the operating speed of the lift arm 111 and bucket 112 increases. Therefore, during loading work, the lift arm speed can be increased in a timely manner, improving the performance of the cargo handling work.

[0048] Furthermore, the main controller 3 controls the cargo handling hydraulic pump 11 to increase its tilt at the timing when the clutch disengagement mechanism 21 is activated, so that the power of the engine 190 can be quickly used by the cargo handling hydraulic pump 11. This allows cargo handling work to be carried out more efficiently.

[0049] Moreover, when the engine 190 is in an idling state, the clutch disengagement mechanism 21 is operated to increase the tilt of the cargo handling hydraulic pump 11, thereby enabling the driving force of the engine 190 to be used more effectively for cargo handling work.

[0050] Furthermore, the priority valve 14 is switched to the junction position at the timing when the clutch disengagement mechanism 21 is activated, and pressure oil from the accessory pump 12 for driving the fan 24 (auxiliary equipment) is supplied to the lift arm cylinder 117 and the bucket cylinder 115. Therefore, when the clutch disengagement mechanism 21 is activated, the operating speed of the lift arm 111 and the bucket 112 can be increased immediately, thereby further improving the efficiency of cargo handling operations.

[0051] (Second embodiment) Next, a second embodiment of the present invention will be described. A wheel loader 200 according to the second embodiment differs from the wheel loader 100 according to the first embodiment in terms of the traveling drive system. Specifically, whereas the wheel loader 100 according to the first embodiment has a torque converter type traveling drive system, the wheel loader 200 according to the second embodiment has an HST (hydrostatic transmission) type traveling drive system.

[0052] FIG. 5 is a system configuration diagram showing an example of the configuration of a drive system of a wheel loader 200. As shown in FIG. 5, the wheel loader 200 converts the power of the engine 190 into hydraulic pressure and transmits it to the tires 10. Specifically, the wheel loader 200 is equipped with an HST pump 30 connected to the output shaft of the engine 190, and an HST motor 31 that is rotationally driven by pressure oil discharged from the HST pump 30. The rotation of the HST motor 31 then drives the tires 10 to rotate via the axle device 9. In addition, when the operator depresses the brake pedal 6, the tilt of the HST pump 30 is reduced, decelerating and stopping the wheel loader 200. In FIG. 2, reference numeral 32 denotes an HST charge pump, and reference numeral 35 denotes a pressure sensor.

[0053] Next, the control of lift acceleration (increase in the speed of cargo handling work) by the main controller 3 will be described. FIG. 6 is a flowchart showing the procedure of the control process of lift acceleration by the main controller 3. As shown in FIG. 6, the main controller 3 determines whether an inching operation is being performed (S110). Specifically, the main controller 3 determines whether the vehicle body is moving at a low speed or is stopped based on the actual engine speed of the engine 190 from the actual engine speed sensor 18 and the motor speed of the HST motor 31 from the motor speed sensor 36 (brake state detector). That is, in S110, the main controller 3 determines whether the vehicle body is stopped (or is about to stop). In the case of an HST-type drive system as in the second embodiment, since the clutch disengagement mechanism 21 is not provided, the main controller 3 determines whether an inching operation is being performed based on the speeds of the engine 190 and the HST motor 31, thereby determining whether the vehicle body is stopped (or is about to stop).

[0054] If an inching operation is being performed (S110 / YES), the main controller 3 increases the tilt of the cargo handling hydraulic pump 11 and advances the lift acceleration operation timing more quickly than usual (S120). That is, when the main controller 3 determines that the vehicle body is stopped (or is about to stop), it immediately increases the tilt of the cargo handling hydraulic pump 11 to increase the flow rate of pressure oil supplied to the lift arm cylinder 117 and the bucket cylinder 115 (lift acceleration) without waiting for the rotation speed of the engine 190 to reach a high rotation range from an idle state (rotation speed N1 in FIG. 4). Therefore, it is possible to perform lift acceleration when the engine rotation speed is at rotation speed N1, which is in the low rotation range (idle state).

[0055] Then, when the operator releases the brake pedal 6, the motor rotation speed of the HST motor 31 detected by the motor rotation speed sensor 36 increases and exceeds the threshold value. Then, the main controller 3 determines that an inching operation is not being performed (S130 / YES), and returns the tilt of the cargo handling hydraulic pump 11 to normal, and also returns the lift acceleration operation timing to normal (S140).

[0056] As described above, the second embodiment is also expected to improve cargo handling operations, similar to the first embodiment. That is, the present invention can be applied not only to torque converter-type traveling drive systems but also to HST-type drive systems, and contributes to improving cargo handling operations in either case.

[0057] The present invention is not limited to the above-described embodiments, and includes various modifications within the scope of the gist thereof. For example, the present invention is not limited to those having all of the configurations described in the above-described embodiments, and also includes those in which some of the configurations are omitted. Furthermore, it is possible to add or replace some of the configurations of one embodiment with the configurations of another embodiment. Other aspects conceivable within the scope of the technical idea of ​​the present invention are also included in the scope of the present invention. [Explanation of symbols]

[0058] 1: Engine controller 3: Main controller (control device) 4: Forward / reverse indicator lever 5: Accelerator pedal 6: Brake pedal (braking device) 7: Torque converter (driving force transmission device) 8: Transmission (driving force transmission device) 9: Axle device 10: Tires 11: Hydraulic pump for cargo handling (hydraulic pump) 12: Accessory pump for auxiliary equipment (accessory pump) 13: Control valve 14: Priority valve 17: Loading operation lever 18: Actual engine speed sensor 19: Brake pressure sensor (brake condition detector) 20: Transmission control unit (control device) 21: Clutch cut mechanism 22: Fan drive system 23: Fan motor (hydraulic actuator for auxiliary equipment) 24: Fan (auxiliary) 30: HST pump (driving force transmission device) 31: HST motor (driving force transmission device) 32: HST charge pump 35: Pressure sensor 36: Motor rotation speed sensor (brake status detector) 100, 200: Wheel loader (work vehicle) 101: Center pin 110: Front body (body) 111: Lift arm 112: Bucket 114: Work equipment 115: Bucket cylinder (hydraulic actuator) 116: Steering cylinder 117: Lift arm cylinder (hydraulic actuator) 120: Rear body (body) 121: Driver's cab 122: Engine room 123: Counterweight 190: Engine (prime mover)

Claims

1. The car body and a working device provided at the front of the vehicle body; a prime mover mounted on the vehicle body; a variable displacement hydraulic pump driven by the prime mover and supplying pressure oil; a hydraulic actuator that drives the working device with pressure oil supplied from the hydraulic pump; a driving force transmission device that transmits the power of the prime mover to the vehicle body as a driving force for traveling; a brake device that brakes the running of the vehicle body; a brake state detector that detects the operating state of the brake device; A work vehicle equipped with a control device, The control device a determination as to whether the vehicle body is in a stopped state or is about to stop based on a detection signal from the brake state detector, and when it is determined that the vehicle body is in a stopped state or is about to stop and the transmission of the driving force to the vehicle body is interrupted or limited by the driving force transmission device, a control is performed to increase the capacity of the hydraulic pump; A work vehicle characterized by:

2. The work vehicle according to claim 1, the control device adjusts the timing of increasing the displacement of the hydraulic pump to the timing of cutting off or restricting the transmission of the driving force to the vehicle body by the driving force transmission device. A work vehicle characterized by:

3. The work vehicle according to claim 1, An auxiliary machine mounted on the vehicle body; an accessory pump driven by the prime mover and supplying pressure oil; an accessory hydraulic actuator that drives the accessory with pressure oil supplied from the accessory pump, When control to increase the displacement of the hydraulic pump is performed, the control device supplies at least a portion of the pressure oil supplied from the accessory pump to the hydraulic actuator for auxiliary equipment to the hydraulic actuator. A work vehicle characterized by:

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