JPH10121510A - Automatic stop controller for front working member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily adjust automatic stop position of a front working member by using a simple construction in an automatic stop controller of a front working member. SOLUTION: In this automatic stop controller, if a bucket operation lever 9 is operated to a full stroke to Bu side (scooping side) when the level sensor 32 is ON, that is, an electric magnet 23 is in excited state, a spool of a direction switching valve 22 is held at Qb position, the operating oil of a hydraulic source 21 flows to a bottom side of a bucket cylinder 5, a bucket cylinder 5 is elongated, a bucket directed downward is gradually moved upward. Then, a distance Lx from a detection plate to a level sensor 32 is gradually increased, the level sensor 32 is turned off when the distance Lx reaches the operation distance Lx0 set by an operation distance change device 33, the electromagnet 23 is demagnetized, the spool of the direction switching valve 22 returns to the neutral position Rb, the bucket cylinder 5 stops and then the bucket stops.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic stop control device for a front work member, and more particularly to an automatic stop control device for a front work member provided in a work vehicle such as a shovel loader.

[0002]

2. Description of the Related Art A work vehicle such as a shovel loader includes, for example, a vehicle body having a rear frame provided with a driver's seat and a front frame mounted on the rear frame so as to be able to turn left and right. A lift arm rotatably mounted on the lift arm, a bucket rotatably mounted on the distal end of the lift arm in a vertical direction, and an arm cylinder for rotating the lift arm in a vertical direction by hydraulic oil of a hydraulic source. A bucket cylinder for rotating the bucket in the vertical direction by hydraulic oil from a hydraulic source, an arm direction switching valve connected between the hydraulic source and the arm cylinder, the position of a spool being switched by an arm operating lever, and a hydraulic source. Direction connected to the bucket cylinder and the position of the spool is switched by the bucket operating lever And a valve.

Some of the work vehicles described above are provided with an automatic stop control device for automatically stopping the lift arm and the bucket at predetermined positions so that the operator can work efficiently. . The automatic stop control device of the lift arm is intended to automatically stop the lift arm at the height position when the bucket is lifted to a predetermined height position and gravel or quarry is put into a hopper (a dump truck or the like). used. On the other hand, the automatic bucket stop control device is usually used for automatically stopping the bucket so as to be horizontal with respect to the ground in order to make the excavated surface uniform when excavating the ground or removing snow. In some cases, the bucket is tilted forward and backward to adjust the excavation depth. In this case, the bucket is automatically stopped at a set angle.

A general lift arm automatic stop control device includes a magnetic body detection plate fixed to one of a front frame and a lift arm of a vehicle body, and a detection plate of a magnetic body fixed to the other of the front frame and the lift arm of the vehicle body. Leveler sensor (proximity switch) that is fixedly installed and is turned on when in proximity to the detection plate and turned off when the detection plate is separated.
When the leveler sensor is ON, the electromagnet is excited to maintain the current switching position of the spool of the arm direction switching valve, and when the leveler sensor is OFF, the electromagnet is demagnetized to neutralize the spool of the arm direction switching valve. And an electromagnet type detent mechanism for returning to a position. In such a configuration, when lifting the lift arm to a predetermined height position after loading gravel or the like in the bucket, the electromagnet is in an excited state, and in this state, the arm operation lever is moved to the arm raising side. When the full-stroke operation is performed, the spool of the arm direction switching valve is switched to a position where the hydraulic oil of the hydraulic pressure source flows to the bottom side of the arm cylinder, and is held at the switching position by the detent mechanism. Then, even if the operator releases the arm operation lever, the lift arm continues to move upward, and the detection plate attached to the lift arm also keeps moving. Then, when the detection plate is separated from the leveler sensor, the electromagnet is demagnetized, the spool of the arm direction switching valve returns to the neutral position, and the lift arm stops.

On the other hand, in a general automatic bucket stop control device, a detection plate is attached to one of a piston rod and a cylinder tube of a bucket cylinder, and a leveler sensor is attached to the other of the piston rod and the cylinder tube of the bucket cylinder. Other than that, it is almost the same as the automatic stop control device of the lift arm.

An automatic stop control device for a lift arm is disclosed in Japanese Utility Model Laid-Open No. 2-6763. The automatic stop control device described in this publication is a general automatic stop control device as described above, in which a push-pull cable is connected between a mounting bracket of a leveler sensor and a control panel of a driver's seat, and an operator receives a signal from the driver's seat. The leveler sensor can be moved relative to the detection plate by remote control.

[0007]

However, the above prior art has the following problems. In a general automatic stop control device, the detection plate and the leveler sensor are fixedly installed with bolts, so that the automatic stop positions of the lift arm and the bucket are fixed. However, the automatic stop position of the lift arm is determined according to the height of the hopper or the like, and the automatic stop position of the bucket is determined according to the angle of the excavation surface. For this reason, when the height of the hopper or the like or the angle of the digging surface changes, the automatic stop position also needs to be changed. In this case, the operator gets off the driver's seat and climbs the front frame (or tires). Loosening the bolt with a wrench or the like, changing the installation position of the detection plate or the leveler sensor, and retightening the bolt are performed, so that the adjustment of the automatic stop position is very complicated and time-consuming.

On the other hand, in the automatic stop control device described in Japanese Utility Model Laid-Open No. 2-6763, the above problem can be solved because the operator can move the leveler sensor relative to the detection plate while in the driver's seat. be able to.
However, in this case, it is necessary to provide a mechanism for holding the position of the leveler sensor after adjusting the installation position of the leveler sensor by pushing and pulling the push-pull cable, which complicates the structure near the leveler sensor. In addition, many devices and hydraulic piping are arranged between the rear frame and the front frame.However, avoiding interference with them and connecting the push-pull cable so as not to bend too much from the viewpoint of durability Have difficulty. Also, when the device described in the above publication is applied to the automatic bucket stop control device, the same problem as described above occurs.

An object of the present invention is to provide an automatic stop control device for a front working member which can easily and automatically adjust the automatic stop position of the front working member.

[0010]

[Means for Solving the Problems]

(1) In order to achieve the above object, the present invention provides a hydraulic cylinder that moves a front working member of a work vehicle, and is fixedly installed on one side of a cylinder tube and a piston rod of the hydraulic cylinder. A proximity switch that turns on before reaching the stroke and turns off when the hydraulic cylinder reaches a predetermined stroke, and an electromagnet that holds a switching position of a directional switching valve corresponding to the hydraulic cylinder, wherein the proximity switch is on. The automatic stop control of the front working member for holding the current switching position of the direction switching valve by exciting the electromagnet and demagnetizing the electromagnet and returning the direction switching valve to the neutral position when the proximity switch is turned off. In the device, the hydraulic cylinder is fixedly installed on the other side of the cylinder tube and the piston rod, A detection plate having an inclined portion for changing the distance between the proximity switch in response to the stroke change of the cylinder, is operated by the operator, a configuration and a working distance changing means for changing the operating distance of the proximity switch.

In the automatic stop control device for the front working member constructed as described above, the proximity switch is turned on to excite the electromagnet to maintain the current switching position of the directional control valve, thereby controlling the operation of the hydraulic cylinder. When the distance between the detection plate and the proximity switch is equal to the operating distance set by the operating distance changing means, the proximity switch is switched from ON to OFF, the electromagnet is demagnetized, and the direction switching valve is set to the neutral position. Returning, the operation of the hydraulic cylinder stops, and the front working member stops. Therefore, when the automatic stop position of the front working member is changed, it is only necessary to change the operating distance of the proximity switch by the operating distance changing means, whereby the stop position of the front working member can be easily and simply adjusted. Can be.

(2) In the above (1), preferably,
The front working member is a lift arm rotatably connected to a front portion of a vehicle body of the work vehicle.

(3) In the above (1), preferably, the front working member is rotatably connected to a distal end portion of a lift arm rotatably connected to a front portion of a vehicle body of the work vehicle. It is a connected bucket.

(4) Further, in the above (1), preferably, the proximity switch is fixedly installed on one of the cylinder tube and the piston rod, and the detection plate is fixedly installed on the other of the cylinder tube and the piston rod. ing.

(5) In the above (2), preferably,
The proximity switch is fixedly installed on one of the vehicle body and the lift arm, and the detection plate is fixedly installed on the other of the vehicle body and the lift arm.

(6) In the above (1), preferably, the apparatus further comprises a display means for displaying a state when the proximity switch is switched between ON and OFF.

[0017]

An embodiment of the present invention will be described below with reference to the drawings. The automatic stop control device for a front working member according to the present embodiment is provided in a shovel loader used for loading work such as earth and sand. Excavator loader
As shown in FIG. 1, a vehicle body 1 having a rear frame 1A, a front frame 1B rotatably connected to the rear frame 1A, and a front frame 1B
And a bucket (including various attachments such as snow removal blades) 3 which is connected to the front end of the lift arm 2 so as to be vertically rotatable and which is connected to the tip of the lift arm 2 so as to be rotatable in the vertical direction. An arm cylinder 4 attached between the vehicle body 1 and the lift arm 2 for rotating the lift arm 2 in the vertical direction; and an arm cylinder 4 attached between the vehicle body 1 and the bucket 3 via a link 6. And a bucket cylinder 5 for rotating the vertical direction. The arm cylinder 4 has a cylinder tube 4 b attached to the vehicle body 1 and a piston rod 4 a attached to the lift arm 2. Bucket cylinder 5
A cylinder tube 5b is attached to the vehicle body 1, and a piston rod 5a is attached to a link 6 connected to the bucket 3. A driver's seat 7 having a handle 11, an arm operating lever 8, and a bucket operating lever 9 is provided at an upper portion of the vehicle body 1.

The above-mentioned shovel loader is equipped with an automatic stop control device for the bucket 3 (hereinafter referred to as bucket leveler) and an automatic stop control device for the lift arm 2 (hereinafter referred to as lift arm leveler). As shown in FIG. 2, the bucket leveler automatically stops the bucket 3 at an angle Lb so as to be horizontal with respect to the ground, and the lift arm leveler puts the lift arm 2 into the hopper 13 with gravel or the like in the bucket 3. The automatic stop is performed at a possible height position La.

As shown in FIG. 3, the hydraulic drive circuit including the bucket leveler includes a direction switching valve 22, an electromagnet type detent mechanism 23, a detection plate 31, a leveler sensor (proximity switch) 32, and an operating distance changing device 33. And a display device 34.

The direction switching valve 22 is connected between the bucket cylinder 5 and the hydraulic pressure source 21 and controls the flow of hydraulic oil supplied from the hydraulic pressure source 21 to the bucket cylinder 5. A cable 17 directly connected to the bucket operation lever 9 is connected to the operation portion 22a of the direction switching valve 22, and the cable 17 is pushed and pulled by operating the bucket operation lever 9, and the spool is switched to the Pb position or the Qb position. .

The electromagnetic detent mechanism 23 includes the directional control valve 2
2, a coil 23a connected to the leveler sensor 32, a fixed iron core 23b provided on the side of the coil 23a, and a movable member fixed to the operation portion 22b, as shown in FIG. And an iron core 23c.
Here, it is assumed that the state in which the coil 23a is energized is that the electromagnet 23 is excited, and that the state in which the coil 23a is not energized is that the electromagnet 23 is demagnetized. Electromagnet 23
When the full-stroke operation of the bucket operating lever 9 is performed to the Bu side (bucket scooping side) in a state where is excited, the spool of the direction switching valve 22 is switched to the Qb position, and the movable iron core 23c is attracted to the fixed iron core 23b. Direction switch valve 2 even if the user releases his / her hand from bucket operation lever 9
The second spool is held in its Qb position. When the electromagnet 23 is demagnetized, the spool of the direction switching valve 22 is returned to the spring force and switched to the neutral position Rb.

The attraction force between the fixed core 23b and the movable core 23c is determined by the fact that the coil 23a is energized and the movable core 23c is energized.
When c is attracted to the fixed iron core 23b, the movable iron core 23c can be relatively easily separated from the fixed iron core 23b by the operation of the bucket operating lever 9 by the operator. Therefore, when the bucket operating lever 9 is operated at full stroke to the Bu side while the electromagnet 23 is energized and the spool of the direction switching valve 22 is switched to the Qb position, the bucket operating lever 9 can be operated without demagnetizing the electromagnet 23. Is operated toward the Bd side, the spool of the directional control valve 22 can be returned to the neutral position Rb.

The detection plate 31 is made of a magnetic material, and has one end fixed to the piston rod 5a of the bucket cylinder 5 with bolts 41 as shown in FIG. Also,
The detecting plate 31 is inclined at an angle θ1 with respect to the bucket cylinder 5 from the end on the side opposite to the installation side to the center so that the distance from the leveler sensor 32 increases when the bucket cylinder 5 is extended.

The leveler sensor 32 is, as shown in FIG.
The bolt 4 is attached to the cylinder tube 5b of the bucket cylinder 5.
2 is attached to the mounting bracket 43 fixedly installed. Further, as shown in FIG. 4, the leveler sensor 32 includes an oscillation circuit 32A, a detection circuit 32B,
2C. The oscillation circuit 32A generates magnetic force lines (dotted lines in the figure) according to a voltage signal (described later) from the operating distance changing device 33. The detection circuit 32B detects whether or not the distance to the detection plate 31 is within the operating distance Lx0 by detecting whether or not the magnetic field lines generated by the oscillation circuit 32A are disturbed. The output opening / closing element 32C is turned on when the distance from the detection plate 31 is within the operation distance Lx0, that is, when the bucket cylinder 5 is moved in the extension direction, before the distance from the detection plate 31 reaches the operation distance Lx0. When the distance from the detection plate 31 reaches the operation distance Lx0 when the distance from the plate 31 is not within the operation distance Lx0, that is, when the bucket cylinder 5 is moved in the extension direction, the switch turns off.

The operating distance changing device 33 is provided in the driver's seat 7, and as shown in FIG. 4, the operator operates the moving distance Lx0 (see FIG. 5) of the leveler sensor 32 corresponding to the stop angle Lb (see FIG. 2) of the bucket 3. ), And a setting circuit 33B including a variable resistor that changes the output voltage in accordance with the operation of the operation means 33A.

The display device 34 is, for example, a light-emitting diode provided in the driver's seat 7.
When the distance to 1 is not within the operating distance Lx0, that is, when the output switching element 32C of the leveler sensor 32 is switched from ON to OFF, light emission is displayed.

As shown in FIG. 6, the hydraulic drive circuit including the lift arm leveler includes a direction switching valve 25, an electromagnet type detent mechanism 26, a detection plate 35, a leveler sensor (proximity switch) 36, and an operating distance changing device 37. And the display device 3
8 is provided.

The direction switching valve 25 is connected between the arm cylinder 4 and the hydraulic source 21 and controls the flow of hydraulic oil supplied from the hydraulic source 21 to the arm cylinder 4. A cable 18 directly connected to the arm operation lever 8 is connected to the operation portion 25a of the direction switching valve 25. By operating the arm operation lever 8, the cable 18 is pushed and pulled, and the spool is switched to the Pa position or the Qa position. . The electromagnet type detent mechanism 26 is provided on the operation portion 25b side of the direction switching valve 25, and has the configuration shown in FIG.
Is the same as

The detection plate 35 is made of a magnetic material in the same manner as the detection plate 31 described above, and as shown in FIG.
When the arm cylinder 4 is extended, the leveler sensor 36
And is fixedly installed with a bolt 45 in a state where it is inclined at an angle θ2 with respect to the lift arm 2 so that the distance Ly with the lift arm 2 becomes long.

The leveler sensor 36 is connected to the front frame 1.
B is fixedly mounted on a mounting bracket 46 fixed by welding, and has the same configuration as the leveler sensor 32 shown in FIG. The leveler sensor 36 turns on when the distance from the detection plate 35 is within the operating distance Ly0 (not shown), and turns off when the distance is not within the operating distance Ly0.

Here, the detection plate 35 is fixedly installed on the lift arm 2 to which the piston rod 4a of the arm cylinder 4 is mounted, and the leveler sensor 36 is mounted on the front of the cylinder tube 4b of the arm cylinder 4 from which the cylinder tube 4b is mounted. Although it is fixed to the frame 1B, it is of course possible to fix the detection plate 35 to the piston rod 4a of the arm cylinder 4 and fix the leveler sensor 36 to the cylinder tube 4b. The cylinder 4 is fixedly installed on the piston rod 4a side of the cylinder 4 and the leveler sensor 36 is
What is necessary is just to fix and install on the side of b.

The operating distance changing device 37 is similar to the above-described operating distance changing device 33, and sets the operating distance Ly0 of the leveler sensor 36. Here, the leveler sensor 36
Is a value corresponding to the stop height La of the lift arm 2 (see FIG. 2). The display device 38 is similar to the above-described display device 34, and emits light when the distance between the leveler sensor 36 and the detection plate 35 is not within the operating distance Ly0.

The operation of the present embodiment configured as described above will be described. After the gravel and the like in the bucket 3 are loaded and unloaded on the hopper 13, the operator operates the bucket operating lever 9 as shown in FIG.
Full stroke operation is performed on the Bu side (scooping side).
Then, the spool of the direction switching valve 22 is switched to the Pb position. At this time, the bucket 3 is directed downward, and the distance between the detection plate 31 and the leveler sensor 32 is within the operating distance Lx0 set by the operating distance changing device 33. Because there is
The electromagnet 23 is in the excited state, so that the directional control valve 22
Is held at the Qb position, the hydraulic oil of the hydraulic pressure source 21 flows to the bottom side of the bucket cylinder 5, the bucket cylinder 5 extends, and the downwardly facing bucket 3 gradually upwards. At this time, since the detection plate 31 attached to the piston rod 5a also moves, the detection plate 31
And the leveler sensor 32 gradually increase the distance Lx. When the distance Lx reaches the operating distance Lx0, the electromagnet 2
3 is demagnetized, and the spool of the directional control valve 22 is in the neutral position R.
Returning to b, the bucket cylinder 5 stops, and as a result, the bucket 3 stops in a state where it is horizontal with respect to the ground. When the distance Lx between the detection plate 31 and the leveler sensor 32 reaches the operating distance Lx0, the display device 34 of the driver's seat 7
Emits light, so that the operator can know that the bucket 3 has stopped.

Thereafter, the operator operates the arm operating lever 8
Is operated to the Ad side (arm lowering side) in FIG. 6 to contract the arm cylinder 4, and the lift arm 2 is lowered to the ground. Then, the vehicle body 1 is advanced to make the bucket 3 penetrate into the earth and sand, and then the bucket operating lever 9 is operated to the Bu side (scooping side) in FIG. 3 to extend the bucket cylinder 5, and the bucket 3 is turned upward. Gravel and the like are scooped into the bucket 3.

Thereafter, the operator moves the vehicle body 1 to a position where the hopper 13 is located, and performs a full stroke operation of the arm operation lever 8 toward the Au side (arm raising side) in FIG. Then, the spool of the directional control valve 25 is switched to the Qa position.
Has descended to the ground, and the detection plate 35 and the leveler sensor 36
Is the operating distance L set by the operating distance changing device 37.
Since it is within y0, the electromagnet 26 is in the excited state, so that the spool of the directional control valve 25 is held at the position Qa,
The hydraulic oil of the hydraulic power source 21 flows to the bottom side of the arm cylinder 4, the arm cylinder 4 extends, and the lift arm 2 gradually rises. At this time, since the detection plate 35 attached to the lift arm 2 also moves, the distance Ly between the detection plate 35 and the leveler sensor 36 gradually increases, and the distance Ly
Has reached the operating distance Ly0, the electromagnet 26 is demagnetized, the spool of the directional control valve 25 is switched to the neutral position Ra, the arm cylinder 4 stops, and as a result, the lift arm 2 removes the gravel and the like in the bucket 3 from the hopper 13 Stop at a height that can be loaded into When the distance Ly between the detection plate 35 and the leveler sensor 36 reaches the operating distance Ly0, the display device 38 of the driver's seat 7 emits light, so that the operator can know that the lift arm 2 has stopped.

Then, the operator operates the bucket operating lever 9 to the Bd side (discharge side) in FIG. 3 so that the bucket 3 faces downward, and the gravel and the like loaded in the bucket 3 are loaded and unloaded on the hopper 13.

Here, as an example of comparison with this embodiment, an example of a conventional automatic stop control device for a front working member is shown in FIGS.
As shown in FIG. FIG. 8 shows a hydraulic drive circuit including a conventional bucket leveler.
A direction switching valve 52, an electromagnet type detent mechanism 56, a detection plate 53, and a leveler sensor 54 are provided. The configurations of the direction switching valve 52 and the electromagnetic detent mechanism 56 are the same as those shown in FIG. As shown in FIG. 9, the detection plate 53 has a straight shape without an inclined portion as in the present embodiment, and is attached to the piston rod 5 a of the bucket cylinder 5 in parallel with the bucket cylinder 5. The leveler sensor 54 is, as shown in FIG.
Is mounted on a mounting bracket 58 fixed to the cylinder tube 5b with a bolt 57, and is turned on when the detection plate 53 is overlapped, and turned off when the detection plate 53 is separated.

In the above configuration, with the electromagnet 56 being excited, the bucket operating lever 9 is
When the full stroke operation is performed on the u side (the rake side), the spool of the direction switching valve 52 is held at the Qb position, the bucket cylinder 5 is extended, and the bucket 3 is gradually turned upward. At this time, the detection plate 53 attached to the rod 5a also moves, and when the detection plate 53 is separated from the leveler sensor 54, the electromagnet 56 is demagnetized, the spool of the direction switching valve 52 is switched to the neutral position Rb, and the bucket 3 stops. I do.

The conventional lift arm leveler has substantially the same configuration as the above-described bucket leveler. However, as shown in FIG. 10, the detection plate 61 is fixedly installed with bolts 64 in parallel with the lift arm 2, and the leveler sensor 62 is mounted on the front frame. 1
It is attached to a mounting bracket 63 fixed to B by welding.

In the above, whether the bucket 3 and the lift arm 2 have reached the automatic stop position is determined by detecting whether the detection plates 53, 61 and the leveler sensors 54, 62 overlap. When the automatic stop positions of the bucket 3 and the lift arm 2 are changed, it is necessary to change the installation positions of the mounting bracket 58 provided with the leveler sensor 54 and the detection plate 61. In this case, the following problem occurs.

(1) To change the automatic stop position of the bucket 3, loosen the bolt 57 and attach the mounting bracket 58 to the slot 5.
8a and by retightening the bolt 57. To change the automatic stop position of the lift arm 2, loosen the bolt 64, move the detection plate 61 along the elongated hole 61a, and retighten the bolt 64. The change work is complicated and time-consuming.

(2) When changing the automatic stop position of the bucket 3 and the lift arm 2, the operator who performs the front operation in the driver's seat 7 interrupts the work, gets off the driver's seat 7, and moves on to the front frame 1 B (or tires). When the automatic stop position does not match, the operator must reciprocate between the driver's seat 7 and the front frame 1B, which is very poor in workability. Therefore, an operator who changes the automatic stop position is required in addition to the operator who performs the front operation.

(3) Adjustment of the automatic stop positions of the bucket 3 and the lift arm 2 requires a tool (spanner or the like) for loosening or tightening the bolts 57 and 64.

On the other hand, according to the automatic stop control device for the front working member of the present embodiment, the detection plate 31 having the inclined portion at the angle θ1 with respect to the bucket cylinder 5 is attached to the piston rod 5a of the bucket cylinder 5,
When the distance Lx from the detection plate 31 is within the operating distance Lx0 set by the operating distance changing device 33, the switch is turned on, and the operating distance L
Since the leveler sensor 32 that is turned off when it is not within x0 is attached to the cylinder tube 5b of the bucket cylinder 5, the automatic stop position of the bucket 3 can be changed only by changing the operation distance Lx0 with the operation distance changing device 33. On the other hand, the detection plate 35 is attached to the lift arm 2 so that the detection plate
The leveler sensor 36 is turned on when the distance Ly with the camera is within the operating distance Ly0 set by the operating distance changing device 37, and is turned off when the distance Ly is not within the operating distance Ly0. The automatic stop position of the lift arm 2 can be changed only by changing the operation distance Ly0 with the changing device 37. Therefore,
Even if the condition of the road surface or the height of the hopper 13 changes, the operator can easily adjust the automatic stop position of the bucket 3 and the lift arm 2 while staying in the driver's seat 7 without interrupting excavation work and snow removal work. And the driver's seat 7 and the detection plate 3
This can be performed with a simple structure without connecting a push-pull cable or the like between the first and second levelers 35 and the leveler sensors 32 and 36.

The detection plates 31 and 35 and the leveler sensor 3
Since the display devices 34 and 38 that emit light when the distance to the operating distances 2 and 36 reach the operating distances Lx0 and Ly0 are provided in the driver's seat 7,
By looking at the display devices 34 and 38, the operator can immediately confirm that the bucket 3 and the lift arm 2 have stopped at the automatic stop position.

In this embodiment, in the bucket leveler, the detection plate 31 is attached to the piston rod 5a of the bucket cylinder 5 and the leveler sensor 32 is attached to the cylinder tube 5b. Leveler sensor 3 on piston rod 5a
2 and the detection plate 31 may be attached to the cylinder tube 5b. On the other hand, in the lift arm leveler, the detection plate 35 is attached to the lift arm 2 and the leveler sensor 36 is attached to the front frame 1B. Conversely, the leveler sensor 3 is attached to the lift arm 2.
6, and the detection plate 35 may be attached to the front frame 1B.

The detection plate 31 is provided with the bucket cylinder 5
Is extended with respect to the bucket cylinder 5 so that the distance from the leveler sensor 32 is increased. However, if the bucket cylinder 5 is extended, the inclination with respect to the leveler sensor 32 may be decreased. . On the other hand, the detection plate 35 is configured to be inclined with respect to the lift arm 2 so that when the arm cylinder 4 is extended, the distance to the leveler sensor 36 becomes longer, but when the arm cylinder 4 is extended, the distance to the leveler sensor 36 is increased. May be inclined so as to be shorter. In these cases, the leveler sensors 32 and 36 are turned on when the distance from the detection plates 31 and 35 is not within the operating distance, and turned off when the distance is within the operating distance.
To do it.

Further, the bucket leveler is for automatically stopping when the bucket cylinder 5 is extended and the bucket 3 is turned upward, and the lift arm leveler is used for extending the lift arm 2 by extending the arm cylinder 4. However, the present invention can also be applied when the bucket cylinder 5 and the arm cylinder 4 are contracted.

Although the bucket cylinder 5 is attached between the vehicle body 1 and the bucket 3 via the link 6, the invention is not limited to this, and the bucket cylinder 5 is attached to the lift arm 2 and the bucket 3. The present invention can be applied to a working vehicle that has been used.

[0050]

According to the present invention, when the automatic stop position of the front working member is changed, it is only necessary to change the operating distance of the proximity switch by the operating distance setting means. Can be performed easily and with a simple structure.

[Brief description of the drawings]

FIG. 1 is a side view of a shovel loader equipped with an automatic stop control device for a front working member according to an embodiment of the present invention.

FIG. 2 is a view showing automatic stop positions of a bucket and a lift arm shown in FIG. 1;

FIG. 3 is a configuration diagram of a hydraulic drive circuit including a bucket automatic stop control device according to an embodiment of the present invention.

FIG. 4 is a configuration diagram showing details of an electromagnet-type detent mechanism, a leveler sensor, and an operating distance changing device shown in FIG. 3;

FIG. 5 is an installation structure diagram of a detection plate and a leveler sensor shown in FIG. 3;

FIG. 6 is a configuration diagram of a hydraulic drive circuit including a lift arm automatic stop control device according to an embodiment of the present invention.

FIG. 7 is an installation structure diagram of a detection plate and a leveler sensor shown in FIG. 6;

FIG. 8 is a configuration diagram of a hydraulic drive circuit including a conventional automatic bucket stop control device.

FIG. 9 is an installation structure diagram of a detection plate and a leveler sensor shown in FIG. 8;

FIG. 10 is an installation structural view of a detection plate and a leveler sensor of a conventional automatic stop control device for a lift arm.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle main body 2 Lift arm (front working member) 3 Bucket (front working member) 4 Arm cylinder 5 Bucket cylinder 22, 25 Direction switching valve 23, 26 Electromagnetic detent mechanism 31, 35 Detection plate 32, 36 Leveler sensor 33, 37 Operation Distance changing device 34, 38 Display device

Claims (6)

[Claims] 1. A hydraulic cylinder for moving a front working member of a work vehicle, fixedly installed on one side of a cylinder tube and a piston rod of the hydraulic cylinder, and turned on before the hydraulic cylinder reaches a predetermined stroke. A proximity switch that is turned off when a predetermined stroke is reached, and an electromagnet that holds a switching position of a direction switching valve corresponding to the hydraulic cylinder, wherein the proximity switch is turned on.
In this case, the electromagnet is excited to maintain the current switching position of the directional control valve, and the proximity switch is
In the automatic stop control device for the front working member that returns the directional switching valve to the neutral position by demagnetizing the electromagnet when the FF is reached, the hydraulic cylinder is fixedly installed on the other side of the cylinder tube and the piston rod of the hydraulic cylinder, A front plate comprising: a detection plate having an inclined portion that changes a distance from the proximity switch in accordance with a change in stroke; and an operation distance changing unit that is operated by an operator and changes an operation distance of the proximity switch. Automatic stop control device for members. 2. The automatic stop control device for a front work member according to claim 1, wherein the front work member is a lift arm rotatably connected to a front portion of a vehicle body of the work vehicle. Automatic stop control device for front working members. 3. The automatic stop control device for a front working member according to claim 1, wherein the front working member is turned to a tip end of a lift arm rotatably connected to a front portion of a vehicle body of the work vehicle. An automatic stop control device for a front working member, which is a bucket movably connected. 4. The automatic stop control device for a front working member according to claim 1, wherein the proximity switch is fixedly installed on one of the cylinder tube and the piston rod, and the detection plate is mounted on the other of the cylinder tube and the piston rod. An automatic stop control device for a front working member, which is fixedly installed. 5. The automatic stop control device for a front working member according to claim 2, wherein the proximity switch is fixedly installed on one of the vehicle body and the lift arm, and the detection plate is mounted on the other of the vehicle body and the lift arm. An automatic stop control device for a front working member, which is fixedly installed. 6. The automatic stop control device for a front working member according to claim 1, wherein said proximity switch is turned on and off.
An automatic stop control device for a front working member, further comprising a display means for displaying the state when F is switched.