JPH0243421A - Control device for travel speed during lifting bucket - Google Patents

Abstract

PURPOSE:To prevent overturning of a shovel loader by detecting the height of an arm when a bucket is lifted high, and thereby adjusting the oil quantity to a hydraulic motor for driving wheels to decrease the travel speed. CONSTITUTION:When a bucket 91 is lifted high, a detection switch 2 fixed on the upper end of a machine-frame 90 detects that an arm 92 reaches a fixed height. A detection signal is sent to a selector valve provided between a hydraulic motor for driving wheels 11, 12 and a hydraulic pump. The selector valve is operated to reduce the oil quantity from the hydraulic pump to the hydraulic motor to decrease the travel speed of a shovel loader 9 and prevent the shovel loader from overturning.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention ensures running safety when lifting a bucket in a shovel loader. The present invention relates to a traveling speed control device.

[Prior art]

As shown in FIG. 6, the shovel loader 9 includes a drive wheel 11.12 provided on a machine base 90, a bucket 91, an arm 92 for operating the bucket 91, and a safety guard 93.
exists. The drive wheels 11, 12 are driven by a hydraulic circuit 8 as shown in FIG. 7 (the figure shows only the drive wheel 11).
2, the hydraulic oil 81 is sent to the H3T hydraulic pump (hydrostatic drive device) 83 to drive the hydraulic pump 83, and the drive wheel 1
1 is rotated.

Specifically, H is provided between the hydraulic pump 83 and the drive wheel 11.
An ST hydraulic motor (hydrostatic motor) 84 is interposed, and hydraulic oil sent from the hydraulic pump 83 is supplied to the hydraulic motor 84.84.
By rotating.

The drive wheels 11 rotate to cause the shovel loader 9 to travel. Note that the hydraulic oil that drove the hydraulic motor 84 returns to the hydraulic pump 83. Further, the hydraulic oil that operated the hydraulic pump 83 returns to the tank 80 through the return oil path 85. Further, the drain oil of the hydraulic motor 84 returns to the tank 80 through an oil path 86.

Further, the load handling operation of the arm 92° bucket 91 in the Shirobell loader 9 is operated by a hydraulic circuit separate from the above. And as shown in FIG.

Scoop up the earth and sand 99 etc. with the bucket 91 and remove the earth and sand 99.
transport it to the designated location. When the mountain of earth and sand 99 gets higher,
Arm 92 must be raised to a considerable height.

(Problem to be Solved) However, 1. For example, when the mountain of the earth and sand 99 becomes high and the bucket 91 is raised to a high position and the shovel loader 9 is run, as shown in FIG. The stability deteriorates, and at 1 o'clock there is a risk that the shovel loader 9 will fall forward as shown in FIG.

If the machine is about to fall, a skilled driver will move the machine further forward to ensure stability and prevent the machine from falling. However, this is an extremely difficult task for ordinary workers, and it is also extremely dangerous.

In view of these problems, the present invention provides a bucket-lift traveling speed control device that allows a shovel loader to travel safely even when lifting loads such as earth and sand to a high place.

[Means for solving the problem] The present invention includes nine machines, a lifting arm connected to the machines,
In an excavator road mite consisting of a bucket provided at the tip of the arm, a hydraulic motor that rotates a drive wheel of the machine, and a hydraulic pump that drives the hydraulic motor, a detection switch for detecting a rise of the bucket; A switching valve for speed control is provided between the hydraulic pump and the hydraulic motor, and the switching valve is actuated by a signal from the detection switch to control the running speed of the shovel loader. A traveling speed control device when a bucket is raised is characterized by the following.

In the present invention, the detection switch may be a mechanical switch such as a limit switch, or a switch such as a magnetic sensor that uses magnetism from an optical sensor.

Such a detection switch is disposed, for example, between the arm and the machine base, and is activated when the inclination angle of the arm reaches a certain level or more (for example, 60 degrees).

Further, the switching valve is actuated by a signal from the detection switch to adjust the amount of hydraulic oil sent from the hydraulic pump to the hydraulic motor, and is configured by, for example, a combination of an oil control valve and a throttle valve.

[Action and effect]

In the traveling speed control device of the present invention, when the arm of the shovel loader is raised and reaches a certain height, the detection switch detects this and a signal is issued to the switching valve. The switching valve is then activated to adjust the amount of hydraulic fluid being sent from the hydraulic pump to the hydraulic motor. Due to this.

The hydraulic motor rotates at a low speed, and therefore the WA drive wheel rotates at a low speed. Therefore, the running speed of the shovel loader is reduced, and it is possible to prevent the shovel loader from falling over.

According to the second aspect of the present invention, it is possible to provide a bucket lifting travel speed control device that allows the shovel loader to travel safely even when the bucket is lifted to a high location.

〔Example〕

First example Regarding the traveling speed control device according to the first embodiment.

This will be explained using FIGS. 1 to 4.

The apparatus of this example is as shown in FIGS. 2 and 3.

A limit switch 2 as a detection switch disposed between a machine base 90 and an arm 92 of the shovel loader 9, and a first
As shown in the figure, a switching valve 5 is provided between a hydraulic pump 83 and a hydraulic motor 84.

The limit switch 2 has its main body 21 fixed to the upper end of a unit 90, and its rotary contact 22 protrudes in the direction of an arm 92. In addition, the switching valve 5 includes an electromagnetically actuated oil control valve 50 and a variable throttle valve 5.
5 and is arranged on the output side of the hydraulic pump 83. The outlet side of the switching valve 5 is connected to the main passage 53 connected to the hydraulic motor 84, and from the hydraulic motor 84 to the hydraulic pump 8.
There is a bypass 54 connected to a return passage 842 to 3. A variable throttle 55 is provided in the bypass 54 .

Next, the operation and effect of this example device will be explained.

First, when the shovel loader 9 is operated without lifting the bucket 91 to a high place.

The oil control valve 50 is in the position shown in FIG. The hydraulic oil 81 in the tank 80 is then sent from the pump 82 to the hydraulic pump 83. And hydraulic pump 83
The passage 51 in the oil control valve 50. Hydraulic oil is sent to the hydraulic motor 84 via the oil passage 53. The hydraulic oil that rotates the hydraulic motor 84 returns to the hydraulic pump 83 through the return passage 842. As a result, the shaft 841 of the hydraulic motor 84 rotates, and the 1wA driving wheel 11 rotates.

The shovel loader 9 runs. In addition, the hydraulic pump 83
．． Drain oil from the hydraulic motor 84 returns to the tank 80 through a return oil path 85.

Next, when the arm 92 of the shovel loader 9 is lifted to a high position, the arm 92 pushes the contact 22 of the limit switch 2, as shown in FIGS. 2 and 3. As a result, limit switch 2 is turned on, relay 23 is activated in the electrical control circuit shown in FIG. 4, and solenoid 4 is activated.
is energized, and the oil control valve 50 is in the first position.
Pushed to the left in the diagram.

As a result, the hydraulic oil discharged from the hydraulic pump 83.

It flows through the passage 52 of the oil control valve 50 to the main passage 53, and also flows through the bypass 54. It also flows to the return passage 842 via the variable throttle 55 . Therefore, the hydraulic motor 84
The amount of oil to the hydraulic motor 84. The rotational speed of the drive wheels 11 decreases, and the running speed of the shovel loader 9 decreases. Therefore, it is possible to prevent the shovel loader 9 from falling.

Note that the degree of the above-mentioned reduction in running speed can be adjusted to 1 by the variable throttle 55.
1H. Further, in FIG. 4, the switch 33 is always in an on state so that the above effects can be obtained. However, as mentioned above, when the speed reduction is not necessary, such as when the original work of the shovel loader is performed by an expert, the switch 33 is turned off as shown by the dotted line. Note that the reference numeral 31 in FIG. It is.

As described above, according to the device of this embodiment, the shovel loader can be operated safely even when traveling with the bucket lifted to a high place.

Second Embodiment As shown in FIG. 5, the traveling speed control device of this embodiment has a second switch 34 provided in parallel with the relay 23 and the switch 33 for experts in the electric control circuit shown in FIG. 4. It is. The rest is the same as the first embodiment.

According to this example, by keeping the second switch 34 on, the shovel loader 9 can always run at a low speed regardless of the height of the bucket 91 of the shovel loader 9. Therefore.

By turning off the second switch 34, which is convenient for working on extremely uneven ground, the same effects as in the first embodiment can be obtained.

[Brief explanation of the drawing]

1 to 4 show a traveling speed control device according to a first embodiment, FIG. 1 is a hydraulic circuit diagram thereof, and FIGS. 2 and 3 are side views showing a state in which a limit switch is installed. FIG. 4 shows an electric control circuit, FIG. 5 shows an electric control circuit in a second embodiment, and FIGS. 6 to 10 show a conventional shovel loader, and FIG. 6 is a side view thereof. FIG. 7 is a hydraulic pressure circuit diagram of the driving wheels, FIG. 8 is a working state diagram of the shovel loader, and FIGS. 9 and 10 are side views showing the shovel loader in running and falling states. 11゜2゜4゜5゜50゜55゜83゜, 11 driving wheels. Limit switch. solenoid. switching valve. oil control valve. Variable aperture. Hydraulic pump. 84°91. . 92° hydraulic motor. Shirobell loader bucket. arm. Ganjin Toyota Industries Corporation Rijin

Claims (1)

[Scope of Claims] A machine base, a lifting arm connected to the machine base, a bucket provided at the tip of the arm, a hydraulic motor that rotates a drive wheel of the machine base, and a hydraulic motor that drives the hydraulic motor. A shovel loader consisting of a hydraulic pump is provided with a detection switch for detecting the rise of the bucket and a switching valve for speed control interposed between the hydraulic pump and the hydraulic motor, and a signal from the detection switch is provided. A traveling speed control device when a bucket is raised, characterized in that the switching valve is actuated to control the traveling speed of a shovel loader.