JPH06299567A - Operation circuit for tilt angle dozer device - Google Patents

Abstract

PURPOSE:To reduce the number of pipings and effect a tilt action and angle action during travelling by a method wherein a tilt angle switching valve which is actuated by pilot pressure is mounted to a lower travelling body so that the tilt angle switching valve serves as a control valve for tilt action and a control valve for angle action. CONSTITUTION:A tilt angle switching valve 35 which is actuated by pilot pressure and a selector valve 37 are connected to a tilt cylinder 6 and an angle cylinder 7, and a control valve 39 for tilt action and angle action is provided. And the selector valve 37 is operated to change over the switching valve 35 to tilt action or angle action, and a speed changeover switch 30 is operated to effect a tilt action and an angle action during the travelling at a first speed (low speed). As a result, the number of pipings passing through a swivel joint 38 can be reduced and operability can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation circuit of a tilt angle dozer device equipped on an upper-slewing construction machine.

[0002]

2. Description of the Related Art FIG. 2 is a cutaway side view of a hydraulic excavator equipped with a tilt angle dozer device. In the figure, 1 is a lower traveling body, 2 is a lower frame of the lower traveling body 1, 3 is an arm for a dozer, 4 is a blade, 5 is a dozer cylinder, 6 is a tilt cylinder, 7 is an angle cylinder, and 8L and 8R are left and right. Traveling motor, 9 is an upper swing body,
Reference numeral 10 is a swing motor, 11 is a swivel joint, and 12 is a work attachment mounted on the front part of the upper swing body 9. FIG. 3 is a perspective view showing the periphery of the blade 4 in FIG. In the figure, 13 is a spherical joint that connects the arm 3 and the blade 4. Arrows a and b indicate the tilt operation direction of the blade 4, and arrows c and d indicate the angle operation direction of the blade 4.

Next, FIG. 4 is a main part circuit diagram showing an operation circuit of a tilt angle dozer device of the prior art. In the figure, 14L and 14R are switching valves for traveling, which control the left and right traveling motors 8L and 8R, respectively, 15, 16, 17, 18
Is a pilot switching valve for controlling various hydraulic actuators equipped on the hydraulic excavator, and 19, 20, 21 are control valves for dozer, tilt, and angle, respectively.
22 is a straight-ahead travel valve, and 23, 24 and 25 are the first and second
Second and third pumps, 26 is a pilot pump, 27 is an oil tank, 28L and 28R are 1s for travel motors 8L and 8R
A second-speed switching valve, 29 is an electromagnetic switching valve provided in the traveling second-speed pilot pressure circuit, and 30 is a first-speed / second-speed switching switch.

As shown in FIGS. 2 and 3, in a hydraulic excavator having a tilt angle dozer device, a lower traveling body 1 is used.
An arm 3 is provided so as to be vertically swingable by a dozer cylinder 5, and an earth-discharging plate 4 is attached to a tip end portion of the arm (3) so as to be tiltably swingable by a tilt cylinder 6. Further, as shown in FIG. 4, in the prior art, when operating the dozer cylinder 5, tilt cylinder 6, and angle cylinder 7, the control valves (19, 20, 21) for dozer, tilt, and angle are operated. . The pressure oil from the third pump 25 is supplied to each cylinder through the control valve and their supply / discharge circuits. If you want to run the hydraulic excavator at high speed,
The first speed-second speed switch 30 is turned on. Since the solenoid 31 of the electromagnetic switching valve 29 is energized, the electromagnetic switching valve 29 is switched from the tank communication oil passage position E to the opening oil passage position. The primary pilot pressure from the pilot pump 26 acts on the pilot ports 34L and 34R of the first-second speed switching valves 28L and 28R via the pipeline 32, the position of the electromagnetic switching valve 29, and the pipeline 33. 1-2 speed switching valve 28L, 2
8R is switched to adjust the motor capacities of the traveling motors 8L and 8R, so that it is possible to switch to traveling second speed.

[0005]

Among the hydraulic excavators, particularly small excavators, the miniaturization and miniaturization thereof are being promoted, and the piping capacity of the swivel joint is also limited. Therefore, it was difficult to separately pass the supply / discharge circuits leading to the dozer, tilt, and angle cylinders through the swivel joint. Therefore, various means have been considered to reduce the number of pipes in the swivel joint by providing a switching valve for selecting the supply / discharge circuit on the lower traveling body, but there is no operation circuit for switching the switching valve effectively and safely. It was It is an object of the present invention to provide an operation circuit for a tilt angle dozer device that can solve the above problems.

[0006]

In the operation circuit of the tilt angle dozer device of the present invention, a dozer arm is provided on the lower traveling body so as to be vertically movable by the dozer cylinder, and the tilt cylinder is tilted by the tilt cylinder at the front end portion of the dozer arm. An upper-slewing type in which a blade is attached so that it can be operated and an angle operation can be performed with an angle cylinder, and the rotational speed of the traveling motor arranged on the lower traveling structure can be switched to the first speed or the second speed by pilot pressure operation. In construction machinery,
A tilt angle switching valve that is switched by pilot pressure is installed on the lower traveling structure, and a tilt cylinder and an angle cylinder are connected in parallel via the tilt angle switching valve to the tilt angle control valve arranged on the upper swing structure. Further, the pilot circuit of the tilt angle switching valve and the pilot pressure circuit for traveling second speed are connected via a selector valve, and the switching position of the selector valve is the pilot pressure hydraulic power source and the pilot circuit of the tilt angle switching valve. When the pilot pressure operation of the first speed or the second speed is selected while the opening oil passage position is selected and operated, both the tilt operation and the angle operation are performed in the first speed state.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a circuit diagram of essential parts showing an operation circuit of a tilt angle dozer device of the present invention. In the figure, the same reference numerals are given to those using the same constituent elements as those in the prior art. Reference numeral 35 is a tilt angle switching valve, 36 is a pilot port of the tilt angle switching valve 35, 37 is a selector valve, 38 is a swivel joint, and 39 is a tilt angle control valve.

Next, the configuration of the operating circuit of the present invention will be described with reference to FIG. According to the present invention, the tilt angle switching valve 35, which is switched by pilot pressure, is arranged on the lower traveling body (not shown) of the hydraulic excavator, and the tilt angle switching valve 35 is arranged with respect to the tilt angle control valve 39 arranged on the upper revolving body side. The tilt cylinder 6 and the angle cylinder 7 are connected in parallel via the valve 35, and the pilot circuit of the tilt angle switching valve 35 (referred to as the conduit 40) and the pilot pressure circuit for the second traveling speed (the conduits 33a-33b are connected to each other). Is connected via a selector valve 37, and the switching position of the selector valve 37 is connected to a pipe 33a communicating with the pilot pump 26 and a pilot pipe (pipe 40) of the tilt angle switching valve 35 to open the oil. Tilt operation and angle operation when pilot pressure operation for traveling 1st or 2nd speed is selected with the road position selected Were all configured to perform in a state of traveling first speed. The selector valve 37 shown in FIG. 1 is a selector valve of a manual switching type or an electromagnetic switching type, and is switched to the open oil passage position of the pipelines 33a-40 or the open oil passage position of the pipelines 33a-33b-40. It is possible.

Next, the operation of the operating circuit of the present invention will be described. The dozer cylinder 5 can be independently and freely controlled by operating the dozer control valve 19. However, the tilt cylinder 6 and the angle cylinder 7 can be controlled by the following four methods. First, as a first operation method, as shown in FIG.
The switch 30 for switching between the second speed and the second speed is turned off, and the selector valve 37 is operated to the position of the oil passage for opening the conduits 33a-40. The pilot angle does not act on the pilot port 36 of the tilt angle switching valve 35 regardless of whether the vehicle is traveling (first speed traveling) or not traveling, so the tilt angle switching valve 35 is in the G position. Therefore, the angle cylinder 7 can be controlled by operating the tilt angle control valve 39. Therefore, for example, when passing through a passage having a narrow width, the angle operation can be adjusted while traveling at the first speed.

Next, as a second operation method, the selector valve 37 is in the state where the conduits 33a-40 are in the open oil passage position, and the first speed / second speed switching switch 30 is turned on. Traveling (in this case, the conduit 33 leading to the 1st-2nd speed switching valves 28L and 28R)
Since b is cut off, the vehicle travels in the first speed.) Regardless of whether or not the vehicle is traveling, the pilot pressure from the pilot pump 26 is fed to the pilot port 36 of the tilt angle switching valve 35 at the position of the electromagnetic switching valve 29. Act through. The tilt angle switching valve 35 switches from the G position to the C position. Therefore, the tilt cylinder 6 can be controlled by operating the tilt angle control valve 39. Therefore, the tilting operation can be adjusted during the dozer work, for example, when the vehicle is traveling in the first speed at a low speed and a large traveling force.

Next, as a third operation method, the selector valve 37 is switched to the open oil passage position of the pipelines 33a-33b-40, and the first-speed / second-speed switching switch 30 is turned off. Since the pilot pressure does not act on the pilot port 36 of the tilt angle switching valve 35 regardless of whether the vehicle is traveling (in this case, the switch 30 for switching between the 1st speed and the 2nd speed is in the off state, the traveling is the 1st speed). The tilt angle switching valve 35 is in the G position. Therefore, as in the case of the first operation method, the angle cylinder 7 can be controlled by operating the tilt angle control valve 39.

Next, as a fourth operation method, the selector valve 37 is switched to the open oil passage position of the pipelines 33a-33b-40, and the first-speed / second-speed switching switch 30 is turned on. The pilot pressure from the pilot pump 26 passes through the position of the electromagnetic switching valve 29 to the 1st-2nd speed switching valve 2
It acts on 8L and 28R and the pilot port 36 of the tilt angle switching valve 35. The tilt angle switching valve 35 is switched from the G position to the C position regardless of whether the vehicle is traveling (in this case, traveling at the second speed) or not traveling. Therefore, the tilt cylinder 6 can be controlled by operating the tilt angle control valve 39. Therefore, in this case, the tilt operation adjustment can be performed while the high speed second speed running is performed. As described above, the tilt angle switching valve 35 is switched effectively and safely and securely by utilizing the pilot pressure circuit for the second traveling speed and switching the selector valve 37, and the tilt cylinder 6 is operated.
And the angle cylinder 7 can be controlled. If the selector valve 37 is omitted, the tilt operation cannot be performed in the first speed running state, which is inconvenient.

[0013]

The small-sized shovel of the prior art is limited in size and weight, and it is difficult to separately pass the supply / discharge circuit leading to each of the tilting cylinder and the angle cylinder through the swivel joint. Therefore, it has been considered to provide a switching valve for selecting the supply / discharge circuit on the lower traveling body, but there is no operation circuit for switching the switching valve effectively and safely. However, in the operation circuit of the present invention, the tilt angle switching valve that is switched by pilot pressure is provided in the lower traveling body of the hydraulic excavator, and the tilt angle switching valve is provided in contrast to the tilt angle control valve disposed in the upper revolving body. The tilt cylinder and the angle cylinder are connected in parallel via the above, and the pilot circuit of the tilt angle switching valve and the pilot pressure circuit for the second traveling speed are connected via the selector valve. Accordingly, by combining the switching of the selector valve and the on / off operation of the first-speed / second-speed switching switch, the tilt cylinder and the angle cylinder can be controlled by a plurality of methods.
Then, among the plurality of methods, the tilt operation and the angle operation can be performed in the state of traveling first speed. That is, in the present invention, by utilizing the pilot circuit for the second speed of travel of the hydraulic excavator and providing the selector valve and the tilt angle switching valve, it is possible to reduce the number of pipes passing through the swivel joint, and to effectively use the tilt angle switching valve. The switching operation can be performed safely and securely.

[Brief description of drawings]

FIG. 1 is a main part circuit diagram showing an operation circuit of a tilt angle dozer device of the present invention.

FIG. 2 is a cutaway side view of a hydraulic excavator equipped with a tilt angle dozer device.

FIG. 3 is a perspective view showing the periphery of the blade in FIG.

FIG. 4 is a main part circuit diagram showing an operation circuit of a tilt angle dozer device of a conventional technique.

[Explanation of symbols]

 1 Lower traveling body 4 Blade 5 Dozer cylinder 6 Tilt cylinder 7 Angle cylinder 8L. 8R Travel motor 11,38 Swivel joint 19 Control valve for dozer 26 Pilot pump 28L, 28R 1-2 speed switching valve 29 Electromagnetic switching valve 30 1st speed-2 speed switching switch 35 Tilt angle switching valve 37 Selector valve 39 Tilt angle Control valve

Claims (1)

[Claims] 1. A lower traveling structure is provided with a dozer arm that can be vertically moved by a dozer cylinder, and a blade is attached to a front end portion of the dozer arm so that the tilt cylinder can perform a tilt operation and the angle cylinder can perform an angle operation. Also, in an upper swing type construction machine in which the rotation speed of a traveling motor arranged on the lower traveling body can be switched to the first speed or the second speed by pilot pressure operation, a tilt angle for switching operation to the lower traveling body by pilot pressure. A tilt valve and a tilt cylinder are connected in parallel through the tilt angle switching valve to a tilt angle control valve that is installed in the upper revolving structure, and a pilot circuit for the tilt angle switching valve is provided. Run 2
Traveling with the speed pilot pressure circuit connected through a selector valve, and the selector valve switching position selected and operated at the opening oil passage position between the pilot pressure hydraulic pressure source and the pilot circuit of the tilt angle switching valve 1 An operating circuit for a tilt angle dozer device, characterized in that, when a pilot pressure operation of speed-2 speed is selected, both the tilt operation and the angle operation are performed in a state of traveling first speed.