JPH05287780A - Controller for heater of working vehicle - Google Patents

Abstract

PURPOSE:To operate a heater without continuous operation of operation lever for long time by operator by a method in which a detent means is kept in operation until the temperature of working oil is at least judged to be more than a given value regardless of the attitude of the working machine. CONSTITUTION:When a direction control valve 8 for bucket is switched to tilting position T by a lever 8a by operator, the bucket 21 is driven toward tilting direction and stopped when a tilt attitude (turning limit attitude) is reached. The pressure of a pipeline 51 is raised, a relief valve 12 is opened, and the pressure of the pipeline 51 is relieved to a tank 13 through pipelines 52 and 53. By heat energy by the pressure losses then, the working oil is heated. The heater of the working oil pressure circuit is operated even when the valve 8 is not kept on the tilting position T by lever operation of operator. Afterwards, when the temperature of working oil is raised to more a given temperature, detent is released by a detent solenoid 32, the valve 8 is automatically restored to neutral position, and the pressure of the pipeline 51 is lowered to close the relief valve 12, thus ending of heating operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a warming-up control device for a work vehicle represented by a wheel loader, and more particularly to performing warming-up by using a detent mechanism for holding the working machine in a predetermined posture. It was done.

[0002]

2. Description of the Related Art Generally, in the above wheel loader,
Oil discharged from a work hydraulic pump driven by an engine is guided to a work hydraulic cylinder via a directional control valve, and the work machine (arm or bucket) is rotationally driven by expansion and contraction of the cylinder. The directional control valve is switched between a neutral position and a work machine drive position by operating the work machine lever, and automatically returns to the neutral position when the lever is released when the work machine drive position is set. There is. In addition, a relief valve is provided in the work pipeline, and the pressure in the work pipeline is maintained below the set relief pressure by the relief valve. That is, for example, if the directional control valve is still held at the working machine drive position by the operating lever after the working machine reaches the rotation limit posture, the pressure in the working pipe line rises, and the pressure increases the set relief pressure. When exceeded, the relief valve opens and the circuit pressure is relieved.

Further, a wheel loader of this type provided with a bucket positioner is known. The bucket positioner means that when the bucket directional control valve is operated to the tilt position (the position for driving the bucket upward, which corresponds to the working machine drive position), the bucket in the dump position reaches the reference position. Until then, the directional control valve is held in its tilted position by the detent mechanism, and when the bucket reaches the reference position, the detent is released and the directional control valve is returned to the neutral position, thereby holding the bucket in the reference position. is there. The reference posture is a posture in which the bottom surface of the bucket is parallel to the ground when the arm reaches the lowermost stage, that is, a posture when the work is started. With the function of this bucket positioner, the operator can dump the bucket, load the soil and the like into the dump truck, and then put the bucket in the reference position with a simple operation, and immediately perform the next work (go to scoop the soil and sand). Work).

In the wheel loader, when the temperature of the hydraulic oil is low, the viscosity of the hydraulic oil is high, and the driving speed of the working machine or the traveling speed of the vehicle is reduced. Warming up is required. Therefore, conventionally, for example, a directional control valve for a bucket is held in a tilt position or a dump position for a certain time, and the bucket is held in a rotation limit posture (tilt posture or dump posture) to operate the relief valve. The hydraulic oil in the work circuit is warmed up by the heat energy due to the pressure loss of the
The hydraulic circuit for traveling is also led to the hydraulic circuit for traveling through the j-pump to warm up the hydraulic circuit for traveling.

[0005]

By the way, the detent mechanism which constitutes the bucket positioner can temporarily hold the directional control valve in the tilt position, but when the bucket reaches the reference position, the directional control is automatically performed. Since the valve is returned to the neutral position, the directional control valve cannot be held in the tilt position for a long time in the conventional configuration, and the detent mechanism cannot be used for warming up. For this reason, conventionally, the operator had to keep operating the work lever for a long time until the hydraulic oil was warmed to hold the directional control valve at, for example, the tilt position. In other words, conventionally, warm-up could not be performed unless the operator was always in the driver's seat.

An object of the present invention is to provide a warm-up control device for a work vehicle, which utilizes the above-mentioned detent mechanism and can perform warm-up even if the operator does not continuously operate the work lever for a long time.

[0007]

The present invention will be described with reference to FIG. 1, FIG. 2 and FIG. 5 showing an embodiment, and a working hydraulic pump 5 driven by an engine 1 and a working hydraulic pump 5 according to the present invention. Work hydraulic cylinders 10 and 11 (FIG. 2) that expand and contract by the oil discharged from the pump 5 to drive the work machine, and a work direction control valve that controls the direction of the pressure oil guided to the work hydraulic cylinders 10 and 11. 8, 9 and the detent means 32 for holding the directional control valve 8 at a predetermined working machine drive position, and the detent means 32 is kept in an operating state until the working machine reaches the reference posture, and the working machine reaches the reference posture. Then, the detent control means 33b for releasing the operation of the detent means 32.
And the working hydraulic pump 5 and the working hydraulic cylinders 10, 1
And a relief means 12 for relieving the pipeline pressure, which operates when the pipeline pressure between the first and the second pressures exceeds a predetermined value, and warms the hydraulic oil by heat energy due to pressure loss when the relief means 12 operates. The above is applied to the warm-up control device for the work vehicle. Then, the above problem is solved by including a determining means 33a for determining whether or not the hydraulic oil temperature is equal to or higher than a predetermined temperature, and configuring the detent control means 33b as follows. That is, when the determination means 33a determines that the hydraulic oil temperature is lower than the predetermined temperature, the detent control means 33b detents at least until the hydraulic oil temperature is determined to be the predetermined value or higher regardless of the posture of the working machine. Hold the means 32 in the activated state. Further, in particular, the invention of claim 2 further comprises a variable displacement hydraulic pump 2 for traveling, and a traveling hydraulic motor 3 connected to the hydraulic pump 2 in a closed circuit by a pair of main pipelines 4a, 4b, and a relief means. The pressure oil warmed up by the heat energy due to the pressure loss during the 12th operation is guided to the pair of main pipe lines 4a and 4b. Further, according to the invention of claim 3, in the case where the hydraulic oil temperature is determined to be below the predetermined temperature, the number of revolutions for increasing the engine rotational speed is higher than that in the case where the hydraulic oil temperature is determined to be above the predetermined value. Control means 33
c and 37 are further provided. Furthermore, claim 4
The invention of (1) is provided with the above-mentioned rotation speed control means 33c, 37, and the displacement volume control means (6) that increases the displacement volume of the variable displacement hydraulic pump 2 as the engine rotation speed increases.
1, 64, 65, 66), a transmission state in which the rotation of the traveling hydraulic motor 3 is transmitted to the wheels, and a disconnection state in which the hydraulic motor 3 and the wheels are disconnected from each other.
And at least the clutch control means 33d, 68 for holding the clutch device 70 in the disengaged state when it is determined that the hydraulic oil temperature is lower than the predetermined temperature. According to the invention of claim 5, the actual hydraulic oil temperature is detected to determine whether the hydraulic oil temperature is equal to or higher than a predetermined temperature. Further, according to the invention of claim 6, the actual hydraulic oil temperature is detected to determine whether the hydraulic oil temperature is equal to or higher than a predetermined temperature, and the elapsed time from when it is first determined to be lower than the predetermined temperature. Based on the above, it is determined whether or not the hydraulic oil temperature has reached a predetermined temperature or higher.

[0008]

When the hydraulic oil temperature is determined to be lower than the predetermined temperature, the detent means 32 keeps the operating oil temperature irrespective of the posture of the working machine 21 until at least the hydraulic oil temperature is determined to be the predetermined value or higher. Hold the operating condition. Therefore, once the directional control valve 8 is switched to the predetermined working machine drive position T, the directional control valve 8 is driven by the working machine even if the operator does not hold the directional control valve 8 at the working machine drive position T by operating the lever. It is held at the position T. By holding the control valve 8 at the working machine drive position T, the working hydraulic cylinder 10 is expanded and contracted to drive the working machine, and after the working machine reaches the rotation limit position, the working hydraulic pump 5 and Working hydraulic cylinder 10,
Since the line pressure between the relief line 11 and
Operates to maintain the relief state. Then, the hydraulic oil is warmed up by the heat energy due to the pressure loss during this relief. Further, particularly in the invention of claim 2, the pressure oil warmed up by the heat energy due to the pressure loss when the relief means 12 is operated is a pair of hydraulic oil pumps 2 for traveling and a hydraulic motor 3 for traveling. Main pipeline 4
It is also led to a and 4b. Therefore, the running hydraulic circuit can be warmed up at the same time. Further, according to the invention of claim 3, when it is determined that the hydraulic oil temperature is lower than the predetermined temperature, the rotation speed of the engine 1 is increased, so that the pressure loss becomes large and the warm-up is promoted. The machine time can be shortened. Furthermore, in the invention of claim 4, at least when the hydraulic oil temperature is determined to be below the predetermined temperature, the rotational speed of the engine 1 increases and the displacement volume of the variable displacement hydraulic pump 2 increases. , Clutch device 7
Since 0 is held in the cutoff state and the hydraulic motor 3 and the wheels are cut off, the running hydraulic circuit can be warmed up without running the vehicle.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used for making the present invention easy to understand. It is not limited to.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in which the present invention is applied to a wheel loader adopting an HST system will be described with reference to FIGS. 1 and 2 are diagrams showing the configuration of a warm-up control device for a wheel loader. 2 is a variable displacement HST pump driven by the engine 1, 3 is this HST pump 2
Is a variable capacity HST motor connected in a closed circuit by a pair of main pipes 4a and 4b, and the vehicle travels by the rotation of this HST motor 3. Reference numeral 61 is a charge pump driven by the engine 1, and its discharge oil is a throttle 6
2, it is led to the pair of main pipes 4a, 4b as charge oil via the pipe 81 and the check valves 63a, 63b.
Further, the discharge oil of the charge pump 61 is guided to the forward / reverse switching valve 65 directly from the pipe line 82 or via the throttle 64 and the pipe line 83, and then is directionally controlled by the forward / reverse switching valve 65 to tilt. Cylinder chambers 66a and 66b of the cylinder 66
Be led to.

The tilting cylinder 66 includes a left and right cylinder chamber 66.
The position of the piston 66c is changed according to the pressures of a and 66b, and thereby the tilt angle and tilt direction of the HST pump 2 are controlled. When the forward / reverse switching valve 65 is in the neutral position (N position), the left and right cylinder chambers 6 are
6a and 66b are communicated with each other to generate the same pressure.
c also holds the neutral position, the tilt angle of the HST pump 2 becomes zero, and the HST pump 2 does not discharge the pressure oil. Further, when the forward / reverse switching valve 65 is at the forward position (F position), the conduit 82 communicates with the left cylinder chamber 66a and the conduit 83 communicates with the right cylinder chamber 66b, so that the piston 66c is The throttle 64 moves to the right in the figure by an amount corresponding to the differential pressure across the throttle 64, and the tilt angle of the HST pump 2 increases toward the forward side accordingly. Further, when the forward / reverse switching valve 65 is in the reverse position (R position), the pipe 83 is located in the left cylinder chamber 6
6a and the conduit 82 is connected to the right cylinder chamber 6
Since it is communicated with 6b, the piston 66c moves leftward in the figure by an amount corresponding to the differential pressure across the throttle 64, and the tilt angle of the HST pump 2 increases toward the reverse side accordingly.

Further, 67 is a transmission charge pump (hereinafter, TM charger) driven by the engine 1.
The discharge oil is a low clutch portion 70a of the transmission 70 via a pipe line 84, an electromagnetic TM disconnect valve 68 and a clutch switching valve 69.
And the Hi clutch portion 70b. The transmission 70 is connected to the HST motor 3, and when pressure oil is introduced to the Lo clutch unit 70a, the rotation of the output shaft 3a of the HST motor 3 is changed to a speed corresponding to the low speed stage (Lo). Transmitted to the wheels, H
When the pressure oil is guided to the i-clutch portion 70b, the rotation of the output shaft 3a is speed-changed to the rotation corresponding to the high speed stage (Hi) and is transmitted to the wheels. In addition, which of the clutch portions 70a, 7
When the pressure oil is not guided to 0b, the output shaft 3a of the HST motor 3 and the wheels are disconnected. Clutch switching valve 69
Is for switching between Lo and Hi, and can be switched to the Hi position and the Lo position according to the operation of an operating member (not shown). Further, the TM disconnect valve 68 has a communication position "a" for connecting the pipe line 84 and the clutch switching valve 69.
Can be switched to a shut-off position "b" for shutting them off.

Further, 5 is a work hydraulic pump driven by the engine 1. The oil discharged from the work hydraulic pump 5 is guided to the steering cylinder 7 via the priority valve 6 in FIG. In addition to contributing, the surplus oil is guided from the priority valve 6 to the bucket cylinder 10 and the arm cylinder 11 through the work pipe line 51, the bucket directional control valve 8, and the arm directional control valve 9.

The direction control valves 8 and 9 are provided with work levers 8a and 9
When the bucket directional control valve 8 is switched from the neutral position N to the tilt position (working machine drive position) T, the bucket cylinder 10 extends,
The bucket 21 is driven in the tilt direction via the bell crank 23 and the link 24 shown in FIG. When the bucket directional control valve 8 is switched to the dump position D, the bucket cylinder 10 contracts and the bucket 21 is driven in the dump direction. Further, when the directional control valve 9 for the arm is switched to the A position, the arm cylinder 11 extends and the arm 22 is driven to rotate upward, and when the directional control valve 9 is switched to the B position, the arm cylinder 11 contracts and the arm 22 rotates downward. Driven. Here, if the hands are released from the work levers 8a and 9a when the directional control valves 8 and 9 are at positions other than the neutral position N, the spring 8
The control valves 8 and 9 are automatically returned to the neutral position N by c and 9c.

In FIG. 2, reference numeral 12 is a relief valve. This relief valve 12 opens when the pressure in the working pipe line 51 exceeds the set relief pressure, and the pressure in the working pipe line 51 is changed to the pipe lines 52, Relief to tank 13 via 53. At the time of this relief, a pressure loss occurs in the relief valve 12 in the circuit, and the heat energy warms up the hydraulic oil.

Next, the structure of the bucket positioner in this embodiment will be described. Reference numeral 31 in FIG. 2 is a bucket 2.
It is a proximity switch that turns on and off according to the posture of 1.
The proximity switch 31 is attached to the cylinder tube 10a of the bucket cylinder 10 as shown in FIG.
On the other hand, a plate member 25 is attached by a bolt to the tip end portion (the portion connected to the bell crank 23) of the piston rod 10b of the bucket cylinder 10.

Then, when the bucket 21 is rotated to the dump side from the reference posture shown in FIG. 3B, FIG.
As shown in FIG. 4B, since the plate member 25 is separated from the proximity switch 31, the proximity switch 31 is off, and when the bucket 21 is rotated from the reference posture to the tilt side, as shown in FIG. Since the plate member 25 crosses the proximity switch 31, the proximity switch 31 is turned on. That is, when the bucket 21 reaches the reference posture, the proximity switch 31 is switched on and off.
Here, the reference posture is a posture in which the bottom surface of the bucket 21 is parallel to the ground when the arm 22 reaches the lowermost stage, as shown in FIG. In other words, if the bucket 21 is held in this reference posture, the bottom surface of the bucket 21 contacts in parallel with the ground when the arm 22 is lowered.

Referring again to FIG. 2, reference numeral 32 is a known detent solenoid for holding the bucket directional control valve 8 at the tilt position T. That is, when the directional control valve 8 is switched to the tilt position T while the detent solenoid 32 is energized, the directional control valve 8 is electromagnetically held (detent) at the tilt position T, and in this state, the solenoid 32 is de-energized. When leaned, the electromagnetic holding is released and the direction control valve 8 automatically returns to the neutral position N by the spring force of the spring 8c. The above is the configuration of the bucket positioner, and its operation will be described in detail later.

Further, reference numeral 33 in FIG. 1 is a controller, and this controller 33, as shown in FIG.
a, a detent control unit 33b, and a rotation speed control unit 33c
A clutch control unit 33d and a ramp control unit 33e. The oil temperature sensor 34 provided in the tank 13 is connected to the determination unit 33a, and it is determined whether or not the temperature of the hydraulic oil, which is the detection result, is equal to or higher than a predetermined temperature. Input to 33e. The warm-up command switch 38 is turned on in each of the control units 33b to 33e.
The off state is input, and the detent control unit 33
The on / off state of the proximity switch SW31 is also input to b.

The detent control unit 33b controls on / off of the detent solenoid 32 based on the input information, and the rotation speed control unit 33c controls the rotation speed of the engine 1 via the rotation speed control device 37. The rotation speed control device 37 controls the rotation of the governor lever of the engine governor by the stepping motor to set the engine rotation speed according to the command from the rotation speed control unit 33c. The clutch control unit 33d controls the switching of the TM disconnect valve 68 to control the presence or absence of pressure oil supply to the transmission 70. The lamp control unit 33e controls turning on / off of the warm-up lamps 35a and 35b via the lamp drive circuit 36. Here, the lamp 35a is for indicating that the warm-up is in progress (for example, red), and the lamp 35b is for indicating that the warm-up is complete (for example, green).

Next, the operation of the embodiment will be described with reference to the flowchart of FIG. FIG. 6 shows a control procedure performed by the controller 33. First, in step S1, the engine speed is controlled by the rotation speed control device 37 via the rotation speed control unit 33c to set the engine speed to the idle rotation speed N0 shown in FIG.
0 rpm). Here, this idle speed N
Since 0 is smaller than the discharge start rotation speed of the HST pump 2, the working oil does not flow in the main pipelines 4a and 4b at this rotation speed, and the warm-up cannot be performed. When it is determined in step S2 that the warm-up command switch 38 is off, the process proceeds to step S3, and the TM disconnect valve 68 is switched to the "a" position (communication position) via the clutch control unit 33d. As a result, the line 84 and the clutch switching valve 69 communicate with each other, and the oil discharged from the TM charge pump 61 pump passes through the clutch switching valve 69 and the Lo clutch portion 7 of the transmission 70.
0a or Hi clutch portion 70b. That is, the shift speed (H
It is possible to drive the vehicle at i or Lo).

Next, in step S4, the proximity switch 31
ON / OFF of is determined. When the proximity switch 31 is on, that is, when the bucket 21 is on the tilt side with respect to the reference posture, the process proceeds to step S5, and the detent control unit 33.
The power supply to the detent solenoid 32 is cut off via b and the process returns to step S1. When the proximity switch 31 is off, that is, when the bucket 21 is on the dump side of the reference posture, the detent solenoid 32 is set in step S6.
Is energized to return to step S1.

According to the above steps S4 to S6, when the warm-up command switch 38 is off and the bucket 21 is on the dump side of the reference posture, the detent solenoid 32 is energized. When the bucket directional control valve 8 is operated to the tilt position T by operating the lever 8a, the direction control valve 8 is held at the tilt position T by the detent solenoid 32 even if the hand is released from the operation lever 8a. Therefore, the bucket cylinder 10 is extended by the pressure oil from the work pipe line 51, and the bucket 21 is driven in the tilt direction. Then, since the proximity switch 31 is turned on when the bucket 21 is in the reference posture,
The detent solenoid 32 is de-energized, the directional control valve 8 is automatically returned to the neutral position N by the spring 8c, and the bucket 21 is held in the reference posture. Arm 2 in this state
When 2 is lowered, the bottom surface of the bucket 21 comes into contact with the ground in a parallel state as described above, so that the next work can be immediately performed.

On the other hand, when it is determined in step S2 that the warm-up command switch 38 is turned on, the determination unit 33a determines from the detection result of the oil temperature sensor 34 whether or not the temperature of the hydraulic oil is equal to or higher than a predetermined temperature. Yes (step S7). When it is determined that the temperature is lower than the predetermined temperature, the lamp control unit 3 is determined in step S8.
The warm-up display lamp 35a is turned on by the lamp drive circuit 36 via 3e, and the TM
The disconnect valve 68 is switched to the “B” position (cutoff position). As a result, the pipeline 84 and the transmission 70 are shut off, and the transmission 70 is communicated with the tank 71 via the switching valve 69 and the TM disconnect valve 68, so that the output shaft 3a of the HST motor 3 and the wheels are shut off. Therefore, the vehicle does not run even if the HST motor 3 rotates.

Next, in step S10, engine speed control for warming up is performed, and in step S11, the detent solenoid 32 is energized, and then the process returns to step S7. Here, the engine speed control for warm-up in the present embodiment is performed as shown in FIG. 5, for example. That is,
During the first 2 minutes after the warm-up command switch 38 is turned on, the engine speed is set to a value N1 (eg, 1500 rpm) higher than the idle speed N0, and thereafter, a higher value N2.
And The rotation speeds N1 and N2 are values exceeding the discharge start rotation speed of the HST pump 2. Further, when it is determined in step S7 that the hydraulic oil temperature is equal to or higher than the predetermined temperature, step S12
In step S12A, the warm-up display lamp 35a is turned off, the warm-up completion lamp 35b is turned on, and in step S13, the engine speed is set to the idle speed N0.
Then, the process proceeds to step S3.

According to the above, when the temperature of the hydraulic oil is lower than the predetermined temperature when the warm-up switch 38 is turned on, the detent solenoid 32 is energized regardless of the attitude of the bucket 21, that is, whether the proximity switch 31 is on or off. At this time, if the operator switches the bucket directional control valve 8 to the tilt position T with the lever 8a, the control valve 8 is held at that position until the hydraulic oil temperature becomes equal to or higher than a predetermined temperature even if the lever 8a is released. The bucket 21 is driven in the tilt direction by switching the directional control valve 8 to the tilt position T, and stops when reaching the tilt attitude (rotation limit attitude) shown in FIG.
Even if the bucket 21 stops in the tilted posture, the directional control valve 8
Is held at the tilt position T, the pressure in the pipeline 51 rises, the relief valve 12 opens, and the pressure in the pipeline 51 is relieved in the tank 13 via the pipelines 52 and 53. Then, the hydraulic oil is warmed up by the heat energy due to the pressure loss at this time. Therefore, even if the operator does not hold the directional control valve 8 at the tilt position T by operating the lever, that is, even if the operator is not in the driver's seat, the working hydraulic circuit can be warmed up. After that, when the temperature of the hydraulic oil rises and becomes equal to or higher than a predetermined temperature, the detent by the detent solenoid 32 is released and the control valve 8
Automatically returns to the neutral position and the pressure in the pipe line 51 decreases, so the relief valve 12 is closed and the warm-up is completed.

Further, in this embodiment, when the temperature of the hydraulic oil is lower than the predetermined temperature, that is, when the warm-up is performed, the rotational speed of the engine 1 is higher than usual, so that the pressure loss increases and the warm-up is increased. It is accelerated, and the warm-up time can be shortened. On the other hand, when the engine speed increases in this way, the discharge pressure of the charge pump 61 increases and the differential pressure across the throttle 64 increases. At this time, the operator operates a switch (not shown) to move the forward / reverse switching valve. When 65 is switched to the F position or the R position, the tilt angle (displacement volume) of the HST pump 2 increases via the tilt cylinder 66 due to the increase in the differential pressure, and the discharge flow rate increases. Therefore, a large amount of pressure oil flows in the main pipelines 4a and 4b, and the traveling hydraulic circuit is warmed up. At this time, the TM disconnect valve 68 is switched to the shutoff position as described above,
The HST motor 3 and the wheels are cut off, so H
Even if the ST motor 3 rotates at high speed, the vehicle will not travel undesirably.

Further, the pressure oil in the tank 13 warmed up by the heat energy due to the pressure loss when the relief valve 12 is operated is passed through the charge pump 61 to the traveling HST.
Main pipelines 4a, 4 connecting the pump 2 and the HST motor 3
Since it is also guided to b, the warming efficiency of the traveling hydraulic circuit can be improved by this also. If the traveling hydraulic circuit is not warmed up,
When the high-temperature pressure oil warmed up from the pump 61 is introduced into the traveling hydraulic circuit, a heat shock may occur. However, in the present embodiment, the traveling hydraulic pressure is increased by increasing the tilt angle of the HST pump 2. Since the circuit is warmed up, even if high-temperature pressure oil is introduced from the charge pump 61, heat shock does not occur, and warm-up efficiency can be improved.

In the configuration of the above embodiment, the bucket hydraulic cylinder 10 and the arm hydraulic cylinder 11 are working hydraulic cylinders, the detent solenoid 32 is a detent means, and the detent controller 3 of the controller 33.
3b is the detent control means, the relief valve 12 is the relief means, the determination unit 33a is the determination means, and the HST pump 2
Is a variable displacement hydraulic pump, the HST motor 3 is a traveling hydraulic motor, and the rotation speed control unit 33c and the rotation speed control device 3 are provided.
Reference numeral 7 designates a rotation speed control means, a charge pump 61, a diaphragm 6
4, the forward / reverse switching valve 65 and the tilt cylinder 66 serve as a displacement volume control means for the Hi, Lo of the transmission 70.
The clutch units 70a and 70b form a clutch device, and the clutch control unit 33d and the TM disconnect valve 68 form a clutch control unit.

In the above description, the actual hydraulic oil temperature is detected by the oil temperature sensor 34, the warm-up control described above is started when the actual hydraulic oil temperature is above the predetermined temperature, and the warm-up control is ended when the temperature falls below the predetermined temperature. However, for example, if the elapsed time after the hydraulic oil is determined to be equal to or higher than the predetermined temperature, that is, the elapsed time from the start of warming up reaches the predetermined time (for example, 15 minutes),
The warm-up control may be stopped when it is determined that the hydraulic oil is at a predetermined temperature or higher. In this case, the engine speed control is also performed, for example, by setting the speed N1 for 2 minutes from the start of warming up
The number of revolutions N2 may be set after the lapse of minutes until the end of warming up. Although the wheel loader adopting the HST system has been described above, the present invention can be applied to a wheel loader using a torque converter instead of the HST system. In this case, only the working hydraulic circuit is warmed up.

Furthermore, the present invention can be applied to construction machines other than wheel loaders. Further, although an example using the detent mechanism of the bucket positioner has been shown, a detent mechanism for detenting the directional control valve may be used for other purposes. Further, the means for controlling the tilt angle of the HST pump 2 is not limited to the embodiment.

[0032]

According to the present invention, when the working oil temperature is lower than the predetermined temperature, the detent means is operated at least until it is determined that the working oil temperature is equal to or higher than the predetermined value regardless of the posture of the working machine. Therefore, once the directional control valve is switched to the work machine drive position, the directional control valve is held at the work machine drive position and the relief means is operated even if the operator does not hold the work lever at that position. It can be operated continuously, and the hydraulic oil can be warmed up due to pressure loss during relief. Further, since the conventional detent mechanism is used, the structure is simplified and the cost is reduced. Further, in particular, according to the invention of claim 2, the pressure oil warmed up by the heat energy due to the pressure loss during the operation of the relief means,
Since it is guided to the pair of main pipes connecting the variable displacement hydraulic pump for traveling and the traveling hydraulic motor, it is possible to warm up the traveling hydraulic circuit at the same time as warming up the working hydraulic circuit. Further, according to the invention of claim 3, the engine speed is increased when it is determined that the hydraulic oil temperature is lower than the predetermined temperature. Therefore, the pressure loss is increased to warm up the hydraulic oil. It is possible to accelerate and shorten the warm-up time. Further, according to the invention of claim 4, at least when it is determined that the hydraulic oil temperature is lower than the predetermined temperature, the engine speed is increased and the clutch device is held in the disengaged state. Therefore, the displacement volume of the traveling variable displacement hydraulic pump can be increased in a state where the rotation of the hydraulic motor is not transmitted to the wheels, and thus the traveling hydraulic circuit can be warmed up without causing the vehicle to travel undesirably. In addition, it is possible to prevent heat shock even if the pressure oil warmed up by the pressure loss is introduced into the traveling hydraulic circuit.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of a warm-up control device according to the present invention.

FIG. 2 is a diagram subsequent to FIG.

FIG. 3 is a diagram illustrating a function of a bucket positioner.

FIG. 4 is a diagram illustrating detection of the attitude of a bucket.

FIG. 5 is a block diagram showing details of a controller.

FIG. 6 is a flowchart showing a processing procedure.

FIG. 7 is a diagram showing the contents of engine speed control.

FIG. 8 is a diagram showing a state in which the bucket is in a tilted posture.

[Explanation of symbols]

 1 Engine 2 HST Pump 3 HST Motor 4a, 4b Main Pipe 5 Work Pump 6 Priority Valve 8 Directional Control Valve for Bucket 9 Directional Control Valve for Arm 10 Bucket Cylinder 11 Arm Cylinder 12 Relief Valve 21 Bucket 22 Arm 31 Proximity Switch 32 Detent Solenoid 33 Controller 33a Judgment part 33b Detent control part 33c Rotation speed control part 33d Clutch control part 33e Lamp control part 34 Oil temperature sensor 35 Warm-up display lamp 37 Rotation speed control device 38 Warm-up command switch 61 Charge pump 64 Throttle 65 Before and after Advance switching valve 66 Tilting cylinder 67 TM Charge pump 68 TM Disconnect valve 69 Clutch switching valve 70 Transmission 70a Lo clutch part 70b Hi clutch part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Osamu Ishimura 650 Jinrachi-cho, Tsuchiura-shi, Ibaraki Hitachi Construction Machinery Co., Ltd. Tsuchiura factory

Claims (6)

[Claims] 1. A working hydraulic pump driven by an engine, a working hydraulic cylinder that expands and contracts by discharge oil of the working hydraulic pump to drive a working machine, and a hydraulic oil guided to the working hydraulic cylinder. A work direction control valve for controlling the direction, a detent means for holding the direction control valve at a predetermined working machine drive position, and a detent means for holding the working machine in an operating state until the working machine reaches a reference posture. When the machine reaches a reference position, the detent control means for releasing the operation of the detent means, and the pipeline pressure between the working hydraulic pump and the working hydraulic cylinder are activated when the pipeline pressure exceeds a predetermined value. A warming-up control device for a working vehicle, which is provided with a relief means for relief and warms the hydraulic oil by heat energy due to a pressure loss during operation of the relief means. A determination means for determining whether or not the hydraulic oil temperature is equal to or higher than a predetermined temperature, and the detent control means, when the determination means determines that the hydraulic oil temperature is lower than the predetermined temperature, A warm-up control device for a work vehicle, which maintains the detent means in an operating state at least until it is determined that the hydraulic oil temperature is at or above a predetermined value regardless of the posture of the machine. 2. A variable displacement hydraulic pump for traveling, and a traveling hydraulic motor connected to the hydraulic pump in a closed circuit by a pair of main pipes. The traveling hydraulic motor is warmed by heat energy due to pressure loss during operation of the relief means. The warming-up control device for a work vehicle according to claim 1, wherein the machined pressure oil is configured to be guided to the pair of main pipelines. 3. A rotation speed control for increasing the rotation speed of the engine when it is determined that the working oil temperature is lower than a predetermined temperature, compared to when it is determined that the working oil temperature is higher than a predetermined temperature. 2. The method according to claim 1, further comprising means.
Alternatively, the work vehicle warm-up control device according to item 2. 4. A rotation speed control for increasing the rotation speed of the engine when it is determined that the working oil temperature is lower than a predetermined temperature, compared to when it is determined that the working oil temperature is higher than a predetermined temperature. Means, displacement volume control means for increasing displacement volume of the variable displacement hydraulic pump as the engine speed increases, transmission state for transmitting rotation of the traveling hydraulic motor to wheels, and the hydraulic motor and wheels And a clutch control means for holding the clutch device in a disengaged state when at least the hydraulic oil temperature is determined to be lower than a predetermined temperature. The warm-up control device for the work vehicle according to claim 2. 5. The determination means detects the actual hydraulic oil temperature and determines whether or not the hydraulic oil temperature is equal to or higher than a predetermined temperature, according to any one of claims 1 to 4. Warming-up control device for the work vehicle described. 6. The determining means detects the actual hydraulic oil temperature to determine whether the hydraulic oil temperature is equal to or higher than a predetermined temperature, and from the time of first determining that the hydraulic oil temperature is lower than the predetermined temperature. The warm-up control device for a work vehicle according to claim 1, wherein it is determined whether or not the hydraulic oil temperature is equal to or higher than a predetermined temperature, based on the elapsed time.