JP2012202433A - Work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a work vehicle including a hydraulic device driving each portion by hydraulic fluid supplied from a hydraulic tank and achieving diagnosis of malfunctions of the whole hydraulic device with high accuracy.SOLUTION: This work vehicle includes the hydraulic device 8 driving each portion by the hydraulic fluid supplied from the hydraulic tank 9, and a detection means 26 detecting pressure of the hydraulic fluid or the flow rate of the hydraulic fluid, and achieves the diagnosis of the malfunctions of the hydraulic device 8 based on a result detected by the detection means 26. The detection means 26 is provided to a return circuit 14 returning the hydraulic fluid to the hydraulic tank 9.

Description

  The present invention relates to a work vehicle provided with a hydraulic device that drives each part with hydraulic oil supplied from a hydraulic tank.

  A hydraulic device that drives each part with hydraulic oil supplied from a hydraulic tank is provided, and a detection unit that detects the pressure of hydraulic fluid or the flow rate of hydraulic fluid is provided, and abnormality diagnosis of the hydraulic device is performed based on the detection result of the detection unit. The work vehicle shown in Patent Document 1 to perform is known.

Japanese Utility Model Publication No. 60-22566

However, since the work vehicle described in the above document has a detecting means arranged on the hydraulic pump side that pumps hydraulic oil in the hydraulic tank to each part, if any abnormality such as leakage occurs in any part to which the hydraulic oil is sent Until the hydraulic oil leaks to the outside, the amount of hydraulic oil in the hydraulic tank becomes insufficient and the hydraulic oil supply by the hydraulic pump becomes abnormal, this abnormality cannot be detected, and the entire hydraulic system is abnormal. The diagnosis may not be accurate.
It is an object of the present invention to provide a work vehicle having a hydraulic device that drives each part with hydraulic oil supplied from a hydraulic tank and capable of performing an abnormality diagnosis of the entire hydraulic device with high accuracy. It is said.

  In order to solve the above-mentioned problem, first, the hydraulic device 8 that drives each part by the hydraulic oil supplied from the hydraulic tank 9 is provided, and the detection means 26 that detects the pressure of the hydraulic oil or the flow rate of the hydraulic oil is provided, A working vehicle for diagnosing an abnormality of the hydraulic device 8 based on the detection result of the detection means 26, wherein the detection means 26 is provided in a return circuit 14 that returns hydraulic oil to the hydraulic tank 9.

  Second, the return circuit 14 is provided with a throttle valve 27, and a detecting means 26 for detecting the pressure of the hydraulic oil is disposed upstream of the throttle valve 27.

  Third, the return circuit 14 is provided with an air suction portion 31a that prevents the hydraulic oil in the hydraulic tank 9 from flowing back to each part through the return circuit 14.

  According to the above configuration, since the detection means for detecting the hydraulic oil pressure or the hydraulic oil flow rate is provided in the return circuit that returns the hydraulic oil to the hydraulic tank, there is an abnormality such as leakage in any part of the hydraulic device. Even if it occurs, it becomes possible to detect the abnormality by the detection means on the return circuit side, the overall abnormality diagnosis accuracy of the hydraulic device is improved, and it is not necessary to separately provide detection means in each part. Cost can be kept low.

  In addition, if a return valve is provided and a detection means for detecting the pressure of the hydraulic oil is arranged upstream of the throttle valve, the pressure of the hydraulic oil is stably maintained at a predetermined level or higher in the normal state. By means, abnormality detection can be performed with higher accuracy.

  In addition, if the return circuit is provided with an air suction section that prevents the hydraulic oil in the hydraulic tank from flowing back to each part via the return circuit, it will be activated by backflow from the hydraulic tank when maintenance or piping breaks. A large amount of oil can be prevented from spilling.

1 is an overall perspective view of an agricultural tractor to which the present invention is applied. It is a hydraulic circuit diagram which shows the structure of a hydraulic device. It is an external view which shows the structure of a return circuit. It is a block diagram of a microcomputer. It is a circuit diagram which shows the structure of a relay circuit. It is a processing flow figure of abnormality diagnosis of the hydraulic device which a microcomputer performs.

  FIG. 1 is an overall perspective view of an agricultural tractor to which the present invention is applied. A tractor, which is a kind of work vehicle, includes a traveling machine body 2 supported by a pair of left and right crawler type traveling devices (traveling units) 1L and 1R, and a rotary tiller that is connected to the rear of the traveling machine body 2 so as to be movable up and down. And a working machine (not shown). The traveling machine body 2 is provided with a bonnet 6 that covers the engine 4 (see FIG. 2) on the front side of the chassis frame 3 so that the chassis frame 3 in the front-rear direction is supported by the left and right crawler type traveling devices 1L and 1R. A cabin 7 is installed behind the bonnet 6 to cover a control unit on which an operator gets.

  The traveling machine body 2 is provided with a hydraulic device 8 (see FIG. 2) that drives the left and right crawler traveling devices 1L and 1R to travel and drives the working machine up and down.

  FIG. 2 is a hydraulic circuit diagram showing the configuration of the hydraulic device. The hydraulic device 8 includes a hydraulic tank 9 into which hydraulic oil has been injected, an external take-out valve unit 11, a work machine valve unit 12, and external oil take-out valve unit 11 and work machine valve unit 12 that supply the hydraulic oil in the hydraulic tank 9. Return pump for returning hydraulic oil discharged from the external take-off valve unit 11 and the work machine valve unit 12 to the hydraulic tank 9 14.

  Since the hydraulic pump 13, the external take-out valve unit 11, and the work implement valve unit 12 are connected in series in the order in which the hydraulic oil flows, the hydraulic oil pumped from the hydraulic pump 13 is It flows in the order of the external take-out valve unit 11 → the work machine valve unit 12.

  The external take-off valve unit 11 can take out the hydraulic oil in the hydraulic device 8 and supply it to an external hydraulic drive device (not shown), and can return the hydraulic oil in the external hydraulic drive device into the hydraulic device 8. A plurality of hydraulic valves 11a are provided. The hydraulic fluid returned from the external hydraulic drive device via the hydraulic valve 11a is returned to the hydraulic tank 9 via the return circuit 14 described above.

  The work machine valve unit 12 includes an ascending valve 12a and a descending valve 12b for extending and retracting the elevating cylinder 16 by supplying and discharging hydraulic oil to and from a hydraulic elevating cylinder 16, and a hydraulic lift rod cylinder 17 And an inclination valve 12c for expanding and contracting the wrist rod cylinder 17 by supplying and discharging hydraulic oil to and from the cylinder.

  The work implement is moved up and down with respect to the traveling machine body 2 by the expansion and contraction of the elevating cylinder 12a, and the work implement is tilted left and right (rolling operation) by the expansion and contraction of the lift rod cylinder 17. Incidentally, the hydraulic oil discharged from the elevating cylinder 16a via the lowering valve 12a and the like and the hydraulic oil discharged from the lift rod cylinder 17 via the inclined valve 12c are returned to the hydraulic tank 9 by the return circuit 14 described above. .

  One HST is provided for each of the crawler type traveling devices 1L and 1R. Each pair of HSTs is a travel pump 18 that is a variable displacement hydraulic pump driven by engine power, and a variable capacity that is driven by hydraulic oil from the travel pump 18 to drive the crawler travel devices 1L and 1R. It is comprised from the travel motor 19 which is a type | formula hydraulic motor. In order to steplessly shift the travel motor 19 that drives the crawler travel devices 1L and 1R, the HST changes the supply amount of hydraulic oil from the travel pump 18 to the travel motor 19 steplessly by a swash plate. To do.

  In addition, each traveling pump 18 is driven by power from the engine 4 and has an auxiliary pump 21 that takes hydraulic oil from the hydraulic tank 9 into the traveling pump 18, and when the pressure due to the internal hydraulic oil exceeds a predetermined level. And a relief valve 22 for discharging the hydraulic oil to the hydraulic tank 9.

  Further, the hydraulic oil of one traveling pump 18 is supplied to a shift switching valve 23 that switches the speeds of both traveling motors 19 and 19 and a brake valve 24 that applies a braking force to both traveling motors 19 and 19. The hydraulic oil discharged from the shift switching valve 23 and the brake valve 24 is also returned to the hydraulic tank 9 via the return circuit 14 described above.

  The return circuit 14 is configured to return the hydraulic oil to the hydraulic tank 9 as described above. The return circuit 14 is a pressure for detecting an abnormality by monitoring the pressure of the hydraulic oil in the hydraulic device 8. A sensor (detection means) 26 is provided. More specifically, the return circuit 14 is configured to return the hydraulic oil discharged from each part via the throttle valve 27 to the hydraulic tank 9, and the pressure in the vicinity of the hydraulic oil flow upstream of the throttle valve 27. A sensor 26 is provided.

  FIG. 3 is an external view showing the configuration of the return circuit. The return circuit 14 includes a plurality of oil distributions 28 that send the hydraulic oil discharged from each part to the hydraulic tank 9 as described above, a manifold 29 that combines the plurality of oil discharge pipes 28 into one, and an oil discharge pipe. The return pipe 31 is configured to return the hydraulic oil that has flowed into the manifold 29 from 28 to the hydraulic tank 9. The manifold 29 is disposed at a position higher than the hydraulic oil level M in the hydraulic tank 9, and the return pipe 31 extends downward in the flow direction. A pipe is provided from a position lower than the liquid level M toward the manifold 29.

  For this reason, when the engine 4 is stopped, if the air in the hydraulic tank 9 is warmed and the internal pressure rises, the hydraulic oil in the hydraulic tank 9 may flow back to the oil discharge pipe 28 due to the siphon phenomenon. In order to prevent this, an air suction hole (air suction portion) 31a is formed near the manifold 29 of the return pipe 31 so that the pressure in the oil drain pipe 28 and the pressure in the hydraulic tank 9 are more than a predetermined value. The pressure difference is prevented from occurring.

  A microcomputer (control unit) 32 that performs abnormality diagnosis of the hydraulic device 8 based on the detection result of the pressure sensor 26 having the above-described configuration is mounted on the truck.

  FIG. 4 is a block diagram of the microcomputer. On the input side of the microcomputer 32, in addition to the pressure sensor 26, a pickup sensor 33, which is an engine rotation detection unit that detects rotation including measurement of the rotation speed of the engine 4, is connected. On the other hand, a buzzer (notification means) 34 for generating a buzzer sound and a relay circuit (engine stop means) 36 for stopping the engine are connected to the output side of the microcomputer 32.

  FIG. 5 is a circuit diagram showing a configuration of the relay circuit. Connected to the relay circuit 36 are a starter switch 37 that is an engine starting operation tool and a fuel cut solenoid 38 that cuts off the supply of fuel to the engine 4. When the engine start operation is being performed by the starter switch 37, the relay circuit 36 turns off the fuel cut solenoid 38 so that the engine 4 can be started, while the engine 32 is stopped from the microcomputer 32. When a signal is input, the fuel cut solenoid 38 is turned on and the engine 4 is stopped. In other words, the microcomputer 32 can stop the engine 4 via the relay circuit 36.

  FIG. 6 is a processing flowchart of abnormality diagnosis of the hydraulic device performed by the microcomputer. When the process is started, the microcomputer 32 proceeds to step S1. In step S1, values of various sensors are read, and the process proceeds to step S2. In step S2, it is confirmed whether or not the engine 4 is rotating through the pickup sensor 33. If the engine 4 is rotating, the operating oil is circulating in the hydraulic device 8, and each part is Since this is a hydraulically operated state and it is necessary to check this state, the process proceeds to step S3.

  In step S3, the pressure of the hydraulic fluid in the return circuit 14 is checked via the pressure sensor 26. If the pressure is reduced, there is a high possibility that leakage or the like has occurred in any part of the hydraulic device 8. Therefore, the process proceeds to step S4. Incidentally, since the throttle valve 27 is provided on the downstream side of the pressure sensor 26, if the engine 4 is in a driven state, the pressure of the hydraulic oil is maintained at a predetermined level or higher in the normal state. The hydraulic pressure check can be performed with high accuracy.

  In step S4, it is checked whether or not a timer has already been set. If the timer has not been set, the process proceeds to step S5. If it has already been set, the process proceeds to step S6. In step S5, a buzzer sounds with a buzzer, and the abnormality of the hydraulic device 8 is notified, and a timer is set to start counting, and the process proceeds to step S6.

  In step S6, the timer count is checked, and if the time is up, the process proceeds to step S7, while if it is still counting, the process returns to step S1. In step S7, the engine 4 is stopped via the relay circuit 36, and the process returns to step S1.

  In step S2, if the engine 4 is in a stopped state, it is not a state in which the hydraulic oil is circulating in the hydraulic device 8, and therefore it is not necessary or necessary to perform a failure diagnosis. Proceed to step S8. In step S8, the timer is reset, and the process returns to step S1.

  In step S3, if the pressure of the hydraulic fluid in the return circuit 14 is not reduced, it can be estimated that the hydraulic device 8 is operating normally. Therefore, the process proceeds to step S8 and the timer is reset. I do.

  According to the above processing, when an abnormality occurs in the hydraulic device 8, first, the process proceeds from step S1, step S2, step S3, step S4, step S5, step S6, step S1, and abnormality notification starts. Thereafter, while the detected value by the pressure sensor 26 shows an abnormal value, until the timer counts up, step S1, step S2, step S3, step S4, step S6, step S1, and so on. If the detected value by the pressure sensor 26 returns to a normal value or the engine 4 is stopped while the process is repeated, the process proceeds to step S8 and the timer is reset.

  If the detected value of the pressure sensor 26 continues to show an abnormal value until a predetermined time elapses after the abnormality is detected by the pressure sensor 26 (until the timer expires), the failure of the hydraulic device 8 becomes serious. Therefore, the processing proceeds from step S6 to step S7, and the engine 4 is stopped.

  Instead of the pressure sensor 26, a flow rate sensor for detecting the flow rate of the hydraulic fluid returned to the return circuit 14 may be provided. In this case, the abnormality diagnosis of the hydraulic device 8 can be performed by comparing the flow rate of the hydraulic oil supplied from the hydraulic tank 9 with the flow rate of the hydraulic oil returned to the hydraulic tank 9. .

1L, 1R crawler type traveling device 2 traveling body 3 chassis frame 4 engine 6 bonnet 7 cabin 7
DESCRIPTION OF SYMBOLS 8 Hydraulic device 9 Hydraulic tank 11 External extraction valve unit 11a Hydraulic valve 12 Work machine valve unit 12a Ascent valve 12b Decline valve 12c Inclination valve 13 Hydraulic pump 14 Return circuit 16 Lifting cylinder 17 Lift rod cylinder 18 Traveling pump (hydraulic pump)
19 Traveling motor (hydraulic pump)
21 Auxiliary pump 22 Relief valve 23 Shift switching valve 24 Brake valve 26 Pressure sensor (detection means)
27 Throttle valve 28 Oil drain pipe 29 Manifold 31 Return pipe 31a Air suction hole (air suction part)
32 Microcomputer (control unit)
33 Pickup sensor (engine rotation detection means)
34 Buzzer (notification means)
36 Relay circuit (engine stop means)
37 Starter switch (engine starting operation tool)
38 Fuel Cut Solenoid M Liquid Level

Claims (3)

  A hydraulic device (8) for driving each part by hydraulic oil supplied from the hydraulic tank (9) is provided, and a detection means (26) for detecting the pressure of the hydraulic oil or the flow rate of the hydraulic oil is provided, and the detection means (26) A working vehicle for diagnosing an abnormality of the hydraulic system (8) based on the detection result of the above, wherein the detecting means (26) is provided in a return circuit (14) for returning hydraulic oil to the hydraulic tank (9). .   The work vehicle according to claim 1, wherein a throttle valve (27) is provided in the return circuit (14), and detection means (26) for detecting the pressure of the hydraulic oil is arranged upstream of the throttle valve (27).   3. The return circuit (14) according to claim 1 or 2, wherein an air suction part (31a) for preventing the hydraulic oil in the hydraulic tank (9) from flowing back to each part through the return circuit (14) is provided in the return circuit (14). Or the working vehicle described.

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