JP2001132009A - Working vehicle posture controller and working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a working vehicle posture controller and a working vehicle, capable of detecting an upper limited position of a boom and a tilted position of a bucket by one sensor. SOLUTION: A detection switch 7 is provided to a bucket cylinder 6, a pendulum plate 9 is vertically hung down rotatably to the lower surface of the cylinder 6, and a longer plate 10 is fixed to a cylinder rod 6a. When a boom 2 is erected by the extension of a boom cylinder 4, the pendulum plate 9 approaches the detection switch 7, and when the boom 2 reaches an upper limited position, the plate 9 approaches the switch 7 to switch on. After the earth-moving of earth and sand or the like, when a bucket 3 is tilted by extension of the bucket cylinder 6, the front end of the longer plate 10 is separated from the detection switch 7 at a specific tilted position and is switched. By the on/off switching of the detection switch 7, the upper limit position of the boom 2 and tilted position of the bucket can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work vehicle attitude control device for controlling the position of a work machine mounted on a work vehicle such as a wheel loader, and a work vehicle provided with the attitude control device.

[0002]

2. Description of the Related Art For example, a working machine in a wheel loader includes a boom mounted on a front part of a vehicle so as to be undulated,
A bucket rotatably attached to the end of the boom is provided. The boom is driven by expansion and contraction of the boom cylinder, and the bucket is driven by expansion and contraction of the bucket cylinder to perform operations such as excavation and earth discharging. In the wheel loader, since operations such as excavation and earth removal are repeatedly performed, it is preferable to control the boom or bucket to an appropriate position without depending on the position of the operator from the viewpoint of improving workability.
An apparatus having such a function is described in, for example, Japanese Utility Model Laid-Open No. 2-2.
No. 3052.

According to the device described in this publication, a detector is provided near the base end of the boom and operates according to the boom angle.
When the detector is turned on when the boom is raised and lowered, the drive of the boom cylinder is stopped, and the boom is held at predetermined upper and lower limit positions.

Further, a detector is provided which operates according to the rotation angle of the bucket. When the detector is activated during rotation of the bucket, the driving of the bucket cylinder is stopped and the bucket is held at a predetermined position corresponding to the work. Some of them are also known.

[0005]

However, to control both the position of the boom and the bucket, a detector for the boom and a detector for the bucket are required separately.
As a result, the number of components increases, the cost increases, and an extra space for mounting the detector is required. Also,
If a detector for detecting the rotation position of the boom is provided in the vicinity of the base end of the boom, the visibility of the operator (for example, the visibility of the front wheels, etc.) is deteriorated.

An object of the present invention is to provide a work vehicle attitude control device capable of controlling both the position of a boom and a bucket with a single detector, and a work vehicle provided with the attitude control device. .

[0007]

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIGS. (1) The invention of claim 1 includes a boom cylinder 4 that supports the boom 2 connected to the vehicle body 1 so as to be able to move up and down, and a working hydraulic pump 12 that is guided to the boom cylinder 4 in response to operation of a boom lever 15. Switch the direction of the pressure oil
Boom direction switching valve 13 that returns to the neutral position when not operated
And a bucket cylinder 6 rotatably supporting a bucket 3 connected to the boom tip via a support member 5 connected to the boom 2, and a pressure guided to the bucket cylinder 6 in response to an operation of a bucket lever 16. Switch the direction of the oil,
Bucket directional switching valve 1 that returns to the neutral position when not operated
4 is applied to a posture control device in a work vehicle including A single detecting means 7, which detects the arrival of the bucket cylinder 6 at the first and second predetermined angles θ1, θ3,
Boom lever holding means 13d for holding the boom direction switching valve 13, which has been switched to the predetermined position (a) in response to the operation of the boom lever 15, at the predetermined position (a).
A predetermined position (a) according to the operation of the bucket lever 16
Lever holding means 14d for holding the bucket direction switching valve 14 switched to the predetermined position (a), and the boom direction switching valve 13 in response to the operation of the boom lever 15.
Is switched to the predetermined position (a), the detecting means 7,
Until the arrival of the bucket cylinder 6 at the first predetermined angle θ1 is detected by 9, 10, 23, the boom holding means 1
3d is operated to hold the boom direction switching valve 13 at the predetermined position (a), and when the arrival at the first predetermined angle θ1 is detected, the operation of the boom holding means 13d is released and the boom direction switching valve 13 is released. 13 is returned to the neutral position (c), and when the bucket direction switching valve 14 is switched to the predetermined position (a) in response to the operation of the bucket lever 16, the detecting means 7, 9,
Until the arrival of the bucket cylinder 6 at the second predetermined angle θ3 is detected by 10, 23, the bucket holding means 1
4d, the bucket directional switching valve 14 is held at the predetermined position (a), and when the arrival at the second predetermined angle θ3 is detected, the bucket holding means 14d is released to release the bucket directional switching valve. The above-mentioned object is achieved by providing control means 13s, 14s, 17, 18, 20, 21, 24 for returning the 14 to the neutral position (c). (2) The invention according to claim 2, wherein the detecting means comprises: a rotating member 9 rotatably suspended from the bucket cylinder 6; a moving member 10 which moves in accordance with expansion and contraction of the bucket cylinder 9;
A switch device provided so as to be close to the rotating member and the moving member;
To detect whether or not the switch device 7 has reached the first predetermined angle θ1 when the switch device 7 is turned on or off by approaching or leaving, and the moving member 10 and the switch device 7 are approached or separated from each other so that the switch device 7 is turned on. Alternatively, it is detected whether or not turning off has reached the second predetermined angle θ3. (3) According to a third aspect of the present invention, the detecting means is an angle detector 23 that detects a relative angle θ of the bucket cylinder 6 with respect to the vehicle body. (4) The invention of claim 4 comprises a boom cylinder 4 that supports the boom 2 connected to the vehicle body 1 so as to be able to move up and down, and a working hydraulic pump 12 that is guided to the boom cylinder 4 in response to the operation of the boom lever 15. Switch the direction of the pressure oil
Boom direction switching valve 13 that returns to the neutral position when not operated
And a bucket cylinder 6 rotatably supporting a bucket 3 connected to the boom tip via a support member 5 connected to the boom 2, and a pressure guided to the bucket cylinder 6 in response to an operation of a bucket lever 16. Switch the direction of the oil,
Bucket directional switching valve 1 that returns to the neutral position when not operated
4 is applied to the work vehicle provided with Then, a single detecting means 7, 9, 10, 23 for detecting the arrival of the bucket cylinder 6 at the first and second predetermined angles θ1, θ3, and a predetermined position (a) according to the operation of the boom lever 15 Boom lever holding means 13d for holding the boom direction switching valve 13 switched to the predetermined position (a), and the bucket lever 1
6, a bucket lever holding means 14d for holding the bucket direction switching valve 14 switched to the predetermined position (a) in the predetermined position (a), and a boom direction switching valve in response to the operation of the boom lever 15. When the switch 13 is switched to the predetermined position (a), the boom holding means 13d is operated until the detection means 7, 9, 10, 23 detects that the bucket cylinder 6 has reached the first predetermined angle θ1. The boom direction switching valve 13 is held at a predetermined position (a), and when the arrival at the first predetermined angle θ1 is detected, the boom holding means 13
d is released to return the boom direction switching valve 13 to the neutral position (c), and when the bucket direction switching valve 14 is switched to the predetermined position (a) in response to the operation of the bucket lever 16, it is detected. Until the means 7, 9, 10, and 23 detect that the bucket cylinder 6 reaches the second predetermined angle θ3, the bucket holding means 14d is operated to move the bucket directional control valve 14 to the predetermined position (a). When the arrival at the second predetermined angle θ3 is detected, the bucket holding means 14
control means 13s, 14s, 17, 1 for releasing the operation of d and returning the bucket directional switching valve 14 to the neutral position (c).
The above object is achieved by providing a posture control device having 8, 20, 21, and 24.

[0008] In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used to make the present invention easier to understand. However, the present invention is not limited to this.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a side view of a wheel loader to which the present invention is applied, and FIG. 2 is an enlarged view of a working machine provided at a front. As shown in FIGS. 1 and 2, a pair of left and right booms 2 (only one is shown) are connected to the front part of the vehicle body 1 so as to be able to move up and down. It is connected as possible. The boom 2 is supported by a boom cylinder 4, and the boom 2
Is undulated. The bucket 3 is supported by a bucket cylinder 6 via a bell crank 5, and the bucket 3 is rotated by expansion and contraction of the cylinder 6. At this time, cylinder 6
The ground angle θ of the cylinder 6 changes according to the amount of expansion and contraction of the cylinder 6.
FIGS. 1 and 2 show postures when the vehicle is running.

As shown in FIG. 2, a detection switch 7 is mounted on the peripheral surface (the lower surface in FIG. 2) of the cylinder tube 6a of the bucket cylinder 6, and is located forward of the detection switch 7 of the cylinder tube 6a (on the side of the cylinder rod 6b). Is fixedly provided with one end of a substantially L-shaped bracket 8. A pendulum plate 9 is rotatably hung from the other end of the bracket 8 via a pin, and a protruding portion 9 a is formed at the tip of the plate 9. The projection 9a approaches the detection switch 7 with an increase in the ground angle θ of the bucket cylinder 6, and the detection switch 7 is turned on when the projection 9a approaches the detection switch 7 (see FIG. 6), and is turned off when the projection 9a is separated. A long plate 10 is fixed to the end of the cylinder rod 6b substantially in parallel with the rod 6b.
When the leading end of 0 is close to the detection switch 7 (see FIG. 8), the detection switch 7 is turned on, and when it is separated, it is turned off. By turning on / off the detector 7, the driving of each of the cylinders 4 and 6 is controlled as described later.

FIG. 3 is a circuit diagram of the attitude control device according to the first embodiment. As shown in FIG.
The oil discharged from the hydraulic pump 12 driven by the hydraulic pump 12 is guided to the boom cylinder 4 via the boom directional switching valve 13 and to the bucket cylinder 6 via the bucket directional switching valve 14. The boom direction switching valve 13 is switched by operating a boom lever 15, and the bucket direction switching valve 14 is switched by operating a bucket lever 16. When the boom direction switching valve 13 is switched to the position (a), pressure oil is supplied to the bottom chamber and the boom cylinder 4 is extended. When switched to the position (b), pressure oil is supplied to the rod chamber and the boom cylinder is supplied. When the boom cylinder 4 is retracted and switched to the neutral position, the supply and discharge of the pressure oil to the bottom chamber and the rod chamber are prevented, and the movement of the boom cylinder 4 is stopped. The bucket cylinder 6 also expands and contracts and stops according to the switching positions (a) to (c) of the bucket direction switching valve 14.

The directional control valves 13 and 14 have detent mechanisms 13d and 14d, respectively.
The operation is controlled by the excitation / demagnetization of the solenoids 13s and 14s. That is, the direction switching valve 13 is in the position (a).
When the solenoid 13s is excited in the state where the solenoid valve 13 is switched to the position (a), the detent mechanism 13d operates. When the solenoid 14s is excited while the direction switching valve 14 is switched to the position (a), the detent mechanism 14d operates. This allows
The direction switching valve 13 or 14 is maintained at the position (a) even when the hand is released from the operation lever 15 or 16. When the solenoid 13s is demagnetized in this state, the operation of the detent mechanism 13d of the boom directional switching valve 13 is released, and when the solenoid 14s is demagnetized, the operation of the detent mechanism 14d of the bucket directional switching valve 14 is released. In this case, when the hand is released from the operation lever 15, the direction switching valve 13 is returned to the neutral position by the spring force of the direction switching valve 13. Similarly, when the hand is released from the operation lever 16, the direction switching valve 14 is returned to the neutral position. The detent mechanisms 13d, 14d
Even if is operated, the directional control valves 13, 14 can be switched to any position by manually operating the operation levers 15, 16.

The solenoid 13s of the directional control valve 13 is connected to a power supply 19 via a contact 17s of a relay 17, and the solenoid 14s of the directional control valve 14 is connected to a contact 18 of a relay 18.
s is connected to the power supply 19. The coil 17c of the relay 17 and the coil 18c of the relay 18 are connected in parallel to the power supply 19 via the detection switch 7. Relay 1
When the detection switch 7 is turned on, the coil 17c is energized, the contact 17s is opened, and the solenoid 13s of the boom direction switching valve 13 is demagnetized. When the detection switch 7 is turned off, the circuit to the coil 17c is cut off, the contact 17s is closed, and the solenoid 13s is excited. On the other hand, the relay 18 is a normally open type. When the detection switch 7 is turned on, the coil 18c is energized, the contact 18s is closed, and the solenoid 14s of the bucket direction switching valve 14 is excited.
When the detection switch 7 is turned off, the circuit to the coil 18c is disconnected, the contact 18s is opened, and the solenoid 14s is demagnetized.

Next, the operation of the first embodiment will be described. When starting the excavation work from the front running posture of FIG. 2, the operation lever 15 is operated to switch the boom direction switching valve 13 to the position (b), and the operation lever 16 is operated to operate the bucket direction switching valve. 14 is switched to the position (b). Thereby, the boom cylinder 4
Is retracted and the boom 2 is turned down, and the bucket cylinder 6 is retracted and the bucket 3 is rotated downward (dumped). Then, while operating the operation levers 15 and 16, the boom 2 is tilted down to the lower limit position as shown in FIG. 4 so that the bottom surface of the bucket 3 is in horizontal contact with the ground, and the front is in the excavation posture. From this state, the vehicle is advanced to push the bucket 3 into earth and sand, and at the same time, the operation lever 16 is operated to switch the bucket direction switching valve 14 to the position (a). As a result, the bucket cylinder 6 is extended, and the bucket 3 is rotated upward (tilted), so that soil and the like are stored in the bucket 3.

Next, the vehicle is moved backward to a position immediately before the dump truck by moving the vehicle backward and forward, and
5, the boom direction switching valve 13 is switched to the position (a). Thereby, the boom cylinder 4 is extended and the boom 2 is erected. At this time, since the pendulum plate 9 is separated from the detection switch 7, the detection switch 7 is turned off, and the solenoid 13s is excited. As a result, even if the lever operation is stopped, the direction switching valve 13 is held at the position (a), and the boom 2 continues to stand up. Boom 2 is shown in FIG.
As shown in FIG. 6, which is an enlarged view of a part a in FIG. 5, the protrusion 9a approaches the detection switch 7, and the switch 7 is turned on. As a result, the relay contact 17s is opened, the solenoid 13s is demagnetized, and the operation of the detent mechanism 13d is released. As a result, the direction switching valve 13 is switched to the neutral position, and the rising operation of the boom 2 is stopped. The ground angle of the bucket cylinder 6 at the boom upper limit position is θ1.

When the boom 2 stops at the upper limit position, the operation lever 16 is operated to switch the bucket direction switching valve 14 to the position (b). This causes the bucket cylinder 6 to retract and the bucket 3 to be dumped, as shown in FIG.
The earth and sand in the bucket is released to the dump truck. At this time, as shown in FIG. 8 which is an enlarged view of the part a in FIG. 7, and FIG.
The projection 9a is pushed away from the detection switch 7, and the long plate 10 approaches the detection switch 7, and the detection switch 7 is continuously turned on. At this time, the ground angle of the bucket cylinder 6 is θ2 (<θ1).

When the discharging operation is completed, the operation lever 16 is operated to switch the bucket direction switching valve 14 to the position (a). Thereby, the bucket cylinder 6 is extended and the bucket 3 is tilted. At this time, since the detection switch 7 is turned on due to the proximity of the long plate 10, the solenoid 14s is excited. As a result, the direction switching valve 14 is maintained at the position (a) even when the lever operation is stopped, and the bucket 3
Is continued. When the bucket 3 is tilted to a predetermined position shown in FIG. 10 (this is referred to as a reference position), as shown in FIG. 11 which is an enlarged view of a part of FIG. Move away. At this time, the projection 9a is also kept separated from the detection switch 7 by pushing up the plate 10,
The detection switch 7 is turned off. As a result, the solenoid 14s is demagnetized, the operation of the detent mechanism 14d is released, the directional control valve 14 is switched to the neutral position, and the tilt operation of the bucket 3 is stopped. Here, the reference position is a bucket position corresponding to the excavation posture in FIG. 5, and when the boom 2 is turned over from the reference position, the bottom surface of the bucket 3 becomes parallel to the ground. The ground angle of the bucket cylinder 6 at the reference position is θ3 (<θ1,> θ2). By the way, in the present embodiment, the pendulum plate 9 is pushed up by the long plate 10 in the range of the ground angle θ of the bucket cylinder 6 ≦ θ3.
By appropriately setting the shape and the mounting position of the plate 9, the plate 9 may be naturally separated from the detection switch 7 regardless of the long plate 10.

When the bucket 3 stops at the reference position, the operation lever 15 is operated to switch the boom direction switching valve 13 to the position (b), and the boom 2 is turned over. When the bucket 3 touches the ground, the operation lever 15 is returned to the neutral position. Thereby, the front is controlled to the excavation posture shown in FIG. Thereafter, the same operation as described above is repeated.

As described above, according to the first embodiment, the detection switch 7 is provided on the bucket cylinder 6,
When the pendulum plate 9 is rotatably suspended in front of the detection switch 7 and the ground angle of the bucket cylinder 6 reaches a predetermined angle θ1 due to the extension of the boom cylinder 4 (FIG. 5), the projection 9a of the plate 9 is attached to the switch 7. Since the switch is turned on in close proximity, the upper limit position of the boom 2 can be detected and the boom 2 can be automatically stopped. The long plate 10 is fixed to the cylinder rod 6b of the bucket cylinder 6, and when the ground angle θ of the bucket cylinder 6 reaches a predetermined angle θ3 due to the retraction of the cylinder 6, the plate 10 separates from the switch 7 (FIG. 10). Since the switch is turned off, the predetermined rotation position (reference position) of the bucket 3 can be detected and the bucket 3 can be automatically stopped. As described above, by detecting the upper limit position of the boom 2 and the reference position of the bucket 3 with one detection switch 7, the number of components can be reduced, and the cost can be reduced.

-Second Embodiment- A second embodiment is configured as follows. FIG.
FIG. 6 is a circuit diagram of a posture control device according to a second embodiment. The same parts as those in FIG.
Hereinafter, the differences will be mainly described. As shown in FIG. 12, a control switch 20 is provided between the coil 17c of the relay 17 and the detection switch 7, and a control device 21 is connected to the control switch 20. The control device 21 executes the following processing based on the signal from the detection switch 7 to control the on / off of the control switch 20.

FIG. 13 is a flowchart for explaining the processing in the control device 21. First, in step S1, it is determined whether the detection switch 7 is on. Step S1
Is negative, the process proceeds to step S2, and the timer is initialized (t ← 0). Next, in step S3, the control switch 20 is turned off (open), and the process returns to step S1. As a result, the circuit to the coil 17c is disconnected, and the relay contact 17
s is closed and the solenoid 13s is excited. If step S1 is affirmed, the process proceeds to step S4 and the timer t
Is added to Δt to update the timer t. Next, in step S5, it is determined whether or not the timer t has counted a predetermined time t1, and if affirmative, the control switch 2 is determined in step S6.
0 is turned on (closed), and the process returns to step S1. This allows
The coil 17c is energized, the relay contact 17s is opened, and the solenoid 13s is demagnetized. If step S5 is denied, the process proceeds to step S7, where the control switch 20 is turned off and the process returns to step S1. As a result, the circuit to the coil 17c is disconnected, the relay contact 17s is closed, and the solenoid 13s is excited.

As described above, according to the second embodiment, the control switch 20 is provided between the coil 17c of the relay 17 and the detection switch 7, and when the ON state of the detection switch 7 is detected for a predetermined time t1, the coil is turned off. Since the power is supplied to the switch 17c, even if the pendulum type plate 9 fluctuates due to wind, vibration, or the like, and comes close to the detection switch 7, malfunction of the detection switch 7 can be prevented.

Third Embodiment In the first and second embodiments, the predetermined boom position and the predetermined bucket position are detected by the proximity of the detection switch 7 to the plates 9 and 10. In the third embodiment, the relative angle of the bucket cylinder 6 with respect to the vehicle body is detected, and the boom position and the bucket position are detected based on the detected value θ. FIG. 14 is a front side view of a wheel loader on which the attitude control device according to the third embodiment is mounted, and a solid line indicates a running attitude. The same parts as those in FIG. 2 are denoted by the same reference numerals, and the differences will be mainly described below. As shown in FIG. 14, an angle detector 23 such as a rotary encoder for detecting the relative angle of the cylinder 6 with respect to the vehicle body is provided at the base end of the bucket cylinder 6.
Are provided, and the detection switch 7 and the plates 9 and 10 are not required.

FIG. 15 is a circuit diagram of an attitude control device according to the third embodiment. The same portions as those in FIG. 3 are denoted by the same reference numerals, and the differences will be mainly described below. As shown in FIG. 15, the angle detector 23 and the relay 1
7, 18 coils 17c, 18c, power supply 19
4 is connected. In the control device 24, the angle detector 23
Based on the signals from the relays 17 and 18, a process described later is executed to control the supply of electricity to the coils 17 c and 18 c of the relays 17 and 18.

FIG. 16 is a flowchart for explaining the processing in the control device 24. First, step S11
It is determined whether or not the detection value θ from the angle detector 23 is smaller than a predetermined value θ1 set in advance. The predetermined value θ1 in this case corresponds to the upper limit position of the boom 2 shown in FIG. If step S11 is affirmed, the process proceeds to step S12, in which the energization of the coil 17c of the relay 17 is stopped and the contact 17s
Close. On the other hand, if step S11 is negative, the process proceeds to step S13, where the coil 17c is energized to open the contact 17s. Proceeding to step S14 following the processing of steps S12 and S13, it is determined whether or not the detection value θ from the angle detector 23 is smaller than a predetermined value θ3. The predetermined value θ3 in this case corresponds to the reference position of the bucket 3 shown in FIG. When step S14 is affirmed, the process proceeds to step S15, in which the coil 18c of the relay 18 is energized to close the contact 18s, and returns to step S11. If step S14 is denied, the process proceeds to step S16, in which the energization of the coil 18c is stopped to release the contact 18s, and the process returns to step S11.

Next, the characteristic operation of the third embodiment will be described. The boom 2 is operated by operating the operation lever 15.
When the angle θ of the bucket cylinder 6 is smaller than the predetermined value θ1, the relay contact 17s is closed, and the solenoid 13s is excited (step S1).
2). Thereby, the detent mechanism 1 of the operation lever 15
3d is activated, and the standing operation of the boom 2 is continued even if the lever operation is stopped. When the angle θ of the cylinder 6 reaches the predetermined value θ1, the coil 17c is energized, the relay contact 17s is opened, and the solenoid 13s is demagnetized (Step S).
13). As a result, the operation of the detent mechanism 13d is released, the rising operation of the boom 2 is stopped, and the boom 2 is held at the upper limit position.

Next, the bucket 3 is dumped by operating the operation lever 16 to release earth and sand in the bucket. At this time, as shown in FIG. 17, the angle θ of the cylinder 6 is θ2 (<θ3), the relay contact 18s is closed, and the solenoid 14s is excited (step S1).
5). Therefore, when the bucket 3 is tilted by operating the operation lever 16, the detent mechanism 1
4d is operated, and the tilt operation of the bucket 3 is continued even if the lever operation is stopped. The angle θ of the cylinder 6 is a predetermined value θ3
Is reached, the relay contact 18s is opened, and the solenoid 14s is demagnetized (step 16). by this,
The operation of the detent mechanism 14d is released, the tilt operation of the bucket 3 is stopped, and the bucket 3 is held at the reference position.

As described above, according to the third embodiment, the relative angle of the bucket cylinder 6 with respect to the vehicle body is detected by the angle detector 23, and the boom 2 is stopped at the upper limit position based on the detected value θ. Since the bucket 3 is stopped at the reference position, it is not necessary to separately provide a sensor for detecting the position of the boom 2 and a sensor for detecting the position of the bucket 3.

In the above-described embodiment, the upper limit position of the boom 2 and the reference position of the bucket 3 are detected by using the detection switch 7 and the angle detector 23, and the upright operation of the boom and the tilt operation of the bucket are automatically performed. Although the stop is performed, the lower limit position of the boom 2 and the dumping position of the bucket 3 may be further detected, and the inversion operation of the boom 2 and the dump operation of the bucket 3 may be automatically stopped. In the above embodiment, the operation levers 15 and 16 are separately provided corresponding to the direction switching valves 13 and 14, but the operation levers are operated in the front-rear direction and the left-right direction corresponding to the direction switching valves 13 and 14. By doing so, one operation lever may be used. Further, in the above embodiment, the attitude control device is applied to the wheel loader. However, the attitude control device can be similarly applied to another work vehicle having the boom 2 and the bucket 3.

In the correspondence between the above embodiments and the claims, the detection switch 7, the pendulum plate 9, and the long plate 10, or the angle detector 23 detects the detecting means, the detent mechanism 13d detects the boom lever holding means, Detent mechanism 1
4d is the bucket holding means, and the solenoids 13s, 14s
And relays 17 and 18 or solenoids 13s and 14s
, Relays 17 and 18, control switch 20 and control device 21
Or solenoids 13s, 14s and relays 17, 18
And the control device 24 constitute control means, the pendulum plate 9 constitutes a rotating member, the long plate 10 constitutes a moving member, the detection switch 7 constitutes a switch device, and the ground angle θ1 of the bucket cylinder 6 is set to a first predetermined value. The ground angle θ3 of the bucket cylinder 6 corresponds to the second predetermined angle.

[0031]

As described in detail above, according to the present invention, a single detecting means for detecting the arrival of the bucket cylinder at the first and second predetermined angles is provided, and the first detecting means detects the first and second angles. Until the arrival at the predetermined angle is detected, the boom directional control valve is held at the predetermined position and the boom is raised and lowered,
When the arrival at the first predetermined angle is detected, the boom directional control valve is returned to the neutral position to stop the boom up / down operation, and until the arrival at the second predetermined angle is detected by the same detection means. Holds the bucket directional control valve at a predetermined position, rotates the bucket, and when arrival at the second predetermined angle is detected, returns the bucket directional control valve to the neutral position to rotate the bucket. Is stopped, the position of both the boom and the bucket can be controlled by one detecting means. Accordingly, it is not necessary to provide a detector near the base end of the boom, so that the visibility of the operator can be prevented from lowering.

According to the second aspect of the present invention, when the switching device is turned on or off when the rotating member rotatably suspended from the bucket cylinder approaches or separates from the switching device and the switch device is turned on or off, the first predetermined condition is obtained. The angle is detected whether or not the moving member moves in accordance with the expansion and contraction of the bucket cylinder, and the switching device approaches or separates, and the switching device is turned on or off. Is detected, the first and second predetermined angles can be detected by a mechanical component that does not use a controller or the like. Further, according to the third aspect of the present invention, since the angle detector detects the relative angle of the bucket cylinder with respect to the vehicle body,
It is possible to reduce the number of attachment parts for detecting the arrival at the first and second predetermined angles.

[Brief description of the drawings]

FIG. 1 is a side view of a wheel loader including an attitude control device according to an embodiment of the present invention.

FIG. 2 is an enlarged front view of a wheel loader provided with the attitude control device according to the first embodiment, showing a traveling attitude.

FIG. 3 is a circuit diagram of the attitude control device according to the first embodiment.

FIG. 4 is an enlarged view of the front of a wheel loader including the attitude control device according to the first embodiment, showing a digging attitude.

FIG. 5 is an enlarged view of the front of the wheel loader provided with the attitude control device according to the first embodiment, showing a boom standing attitude after excavation.

FIG. 6 is an enlarged view of a part a in FIG. 5;

FIG. 7 is an enlarged front view of a wheel loader including the attitude control device according to the first embodiment, showing a dump attitude of a bucket.

8 is an enlarged view of a part a in FIG. 7;

FIG. 9 is an enlarged perspective view of a part a in FIG. 7;

FIG. 10 is an enlarged front view of a wheel loader including the attitude control device according to the first embodiment, showing a tilt attitude of a bucket.

FIG. 11 is an enlarged view of a part a in FIG. 9;

FIG. 12 is a circuit diagram of a posture control device according to a second embodiment.

FIG. 13 is a flowchart showing a process in a control device constituting the attitude control device according to the second embodiment.

FIG. 14 is an enlarged front view of a wheel loader provided with a posture control device according to a third embodiment, showing a running posture and a boom standing posture after excavation.

FIG. 15 is a circuit diagram of an attitude control device according to a third embodiment.

FIG. 16 is a flowchart showing a process performed by a control device constituting the attitude control device according to the third embodiment.

FIG. 17 is an enlarged front view of a wheel loader including the attitude control device according to the third embodiment, showing a traveling attitude, a bucket dumping attitude, and a tilt attitude.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vehicle main body 2 Boom 3 Bucket 4 Boom cylinder 5 Bell crank 6 Bucket cylinder 7 Detection switch 9 Pendulum plate 10 Long plate 13 Boom direction switching valve 14 Bucket direction switching valve 13d, 14d Detent mechanism 13s, 14s Solenoid 15, 16 Operating lever 17, 18 Relay 20 Control switch 21 Control device 23 Angle detector 24 Control device

Claims (4)

[Claims] 1. A boom cylinder for supporting a boom connected to a vehicle body so as to be able to move up and down, and a direction of pressure oil from a working hydraulic pump guided to the boom cylinder in response to an operation of a boom lever, and a non-operation is performed. A boom directional switching valve that returns to a neutral position at the time, a bucket cylinder that rotatably supports a bucket connected to the boom tip via a support member connected to the boom, and a bucket lever operation. A bucket direction switching valve that switches the direction of the pressure oil guided to the bucket cylinder in response to the non-operating state and returns to a neutral position when the bucket cylinder is not operated. A single detecting means for detecting the arrival of the boom at a predetermined angle, and for the boom switched to a predetermined position in response to the operation of the boom lever Boom lever holding means for holding a direction switching valve at the predetermined position; bucket lever holding means for holding the bucket direction switching valve switched to a predetermined position in response to operation of the bucket lever at the predetermined position; When the boom direction switching valve is switched to the predetermined position in response to operation of the boom lever, the boom holding is performed until the detection means detects that the bucket cylinder has reached the first predetermined angle. Activating the boom direction switching valve at the predetermined position, and when the arrival at the first predetermined angle is detected, the operation of the boom holding means is released and the boom direction switching valve is moved. When the bucket direction switching valve is switched to the predetermined position in response to the operation of the bucket lever, the detecting means Until the arrival of the bucket cylinder at the second predetermined angle is detected, the bucket holding means is operated to hold the bucket directional switching valve at the predetermined position, and the bucket direction switching valve is moved to the second predetermined angle. Control means for canceling the operation of the bucket holding means when the arrival is detected and returning the bucket direction switching valve to a neutral position. 2. The work vehicle attitude control device according to claim 1, wherein the detection unit moves in accordance with a rotation member suspended from the bucket cylinder so as to be rotatable, and expansion and contraction of the bucket cylinder. A moving member, and a switch device provided so as to be close to the rotating member and the moving member,
The turning member and the switch device approach or separate from each other to detect whether or not the switch device has reached the first predetermined angle by being turned on or off, and the moving member and the switch device have become close to each other. Alternatively, a posture control device for a work vehicle, wherein whether or not the switch device is turned on or off to detect the arrival at the second predetermined angle is detected. 3. The work vehicle attitude control device according to claim 1, wherein the detection unit is an angle detector that detects a relative angle of the bucket cylinder with respect to a vehicle body. Attitude control device. 4. A boom cylinder for supporting a boom connected to a vehicle body so as to be able to move up and down, and a direction of pressure oil from a working hydraulic pump guided to the boom cylinder in response to an operation of a boom lever, so that no operation is performed. A boom directional switching valve that returns to a neutral position at the time, a bucket cylinder that rotatably supports a bucket connected to the boom tip via a support member connected to the boom, and a bucket lever operation. And a bucket direction switching valve that switches the direction of the pressure oil guided to the bucket cylinder in response to the non-operating state and returns to the neutral position when the bucket cylinder is not operated. A single detecting means for detecting the arrival of the boom, and the boom directional control valve switched to a predetermined position in response to the operation of the boom lever. Boom lever holding means for holding the bucket directional switching valve switched to a predetermined position in response to the operation of the bucket lever, and bucket lever holding means for holding the bucket directional switching valve at the predetermined position; When the boom direction switching valve is switched to the predetermined position, the boom holding means is operated by operating the boom holding means until the detection means detects that the bucket cylinder has reached the first predetermined angle. Holding the boom directional switching valve at the predetermined position, when the arrival to the first predetermined angle is detected, releasing the operation of the boom holding means and returning the boom directional switching valve to the neutral position; When the bucket direction switching valve is switched to the predetermined position in response to the operation of the bucket lever, the bucket cylinder is detected by the detecting means. Until the arrival at the second predetermined angle is detected, the bucket holding means is operated to hold the bucket direction switching valve at the predetermined position, and the arrival at the second predetermined angle is detected. And a control means for releasing the operation of the bucket holding means and returning the bucket direction switching valve to the neutral position.