JPH06128984A - Dozer device for service car - Google Patents

Abstract

PURPOSE:To provide a dozer device capable of improving the finishing state of levelling work by the floating of a dozer while being able to automatically restraining and preventing the appearance of a floating state in the progressive direction not fitted to conduct excellent levelling work and having superior operationability. CONSTITUTION:An electromagnetic changeover valve 9 short-circuiting a pair of oil supply and discharge passages 6a, 6b to a hydraulic cylinder 6 for a dozer while having the position of floating F permitting the free expansion and contraction movement of the hydraulic cylinder 6 by connecting the valve 9 to a drain passage 14 is installed on its midway of an oil passage connecting the hydraulic cylinder 6 and a control valve 7 for the hydraulic cylinder 6. When left and right travelling levers 13, 14 are operated in the direction of backward movement, the switches 15, 16 are turned on, and a controller 10 changes over and operates the changeover valve 9 from a normal position H to the position of floating F, thus automatically bringing the state of levelling work in a backward movement manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a backhoe, a carrier,
Alternatively, it relates to a dozer device for a work vehicle with a dozer such as a wheel loader.

[0002]

2. Description of the Related Art As a work vehicle of this type, for example, as disclosed in Japanese Unexamined Patent Publication No. 4-209216, a dozer has a three-position switching type control valve to switch its operation between upward, downward and neutral. It was something that was done.

[0003]

Among the ground leveling work by the dozer, it is convenient to carry out the work of leveling the soft soil and sand on the so-called back dozer using the back face of the dozer by moving the machine body backward. In other words, the dozer's discharge surface usually has a tilt angle that tilts backward, so when performing the dozer work in reverse, the dozer work can be carried out while pressing down the soil and scraping the soil Compared with work, it is easy to obtain a clean finish. However, in the past, this leveling work was performed with the dozer fixed, so if there is ups and downs on the ground, the pressing force on the ground will change and the leveling will tend to be partially different. Depending on the case, the dozer may leave the ground and create an unleveled area, or it may be pressed too much to scoop the ground, leaving room for improvement in order to obtain a better finish. there were.
An object of the present invention is to further improve the finish condition of the leveling work.

[0004]

In order to achieve the above object, the present invention is directed to a hydraulic cylinder for driving and raising and lowering a dozer, and a hydraulic cylinder by short-circuiting a pair of oil supply / discharge oil passages to the dozer and connecting the oil passages to a drain passage. A switching valve having a floating position that allows free expansion and contraction of the switch, a switching mechanism that switches and operates the switching valve, and a traveling direction detection unit that detects the traveling direction of the machine body. A control means for connecting the switching mechanism and the traveling direction detecting means is provided in a state in which the switching valve can be switched to the floating position only when the traveling state is other than the forward traveling state.

[0005]

[Operation] When the switching valve is operated to the floating position, the hydraulic cylinder freely expands and contracts so that the dozer freely moves up and down. In this floating condition, the downward pressing force due to the weight of the dozer acts on the ground. The dozer can follow the ground surface even if the ground is undulating, and the leveling work can be carried out uniformly without any unpressable parts or gouged parts. Conventionally, as described above, it is preferable to perform the leveling work in the backward traveling state, but the leveling work state in the forward traveling can also be revealed. However, if the dozer bites into the ground due to the shape of the soil dumping plate and the layout of its swing fulcrums, a floating state appears when the dozer moves forward, and the dozer bites deep into the ground so that the dozer pierces the ground, and leveling work. It doesn't. Therefore, the control means is configured so that the switching valve can be switched to the floating position only when the dozer is in the advancing state other than the advancing state, which causes the inconvenience caused by the dozer floating in the advancing. Will be prevented.

[0006]

As a result, the finish of the leveling work can be improved by the dozer floating, and the appearance of the floating state is automatically restrained in the advancing direction which is not suitable for performing the good leveling work. A dozer device with excellent operability can be provided.

[0007]

Embodiments of the present invention will be described below with reference to the drawings when applied to a backhoe which is an example of a work vehicle. A backhoe is shown in FIG. 2, 1 is an excavation work device, 2 is a swivel platform, 3 is a traveling machine platform, 4 is a crawler traveling device, and 5 is a dozer. The dozer 5 is configured by attaching an earth-discharging plate 5b curved in a vertical direction in a side view to the tip of an arm 5a supported by the traveling machine base 3 at the left-right axis P, and can be driven and moved up and down by a hydraulic cylinder 6.

FIG. 1 shows a drive operation system of the dozer 5,
Is a control valve having an ascending position U, a neutral position N and a descending position D, and 8 is an operating lever for operating the control valve 7. In the middle of the pair of oil passages connecting the hydraulic cylinder 6 and the control valve 7, the pair of oil supply and drain passages 6a and 6b for the hydraulic cylinder 6 are short-circuited and connected to the drain passage to freely expand and contract the hydraulic cylinder 6. A switching valve 9 having a floating position F that allows movement is provided. That is, the switching valve 9 has the normal position H and the floating position F, and at the floating position F, the pair of supply / discharge passages 9a, 9a in the valve is provided.
A short circuit 9c for connecting b is provided, and the short circuit 9c is connected to the tank port 9t that follows the drain path 14. As shown by the broken line in FIG.
A pair of supply / discharge passages 9a, 9a are provided in the short-circuit passage 9c of the switching valve 9.
It is convenient if the orifice 18 is provided between b to generate a back pressure in the hydraulic circuit so that the pressing force due to the descent of the dozer 5 in the floating state can be adjusted.

The switching valve 9 includes a return spring 12 and a solenoid 1.
A left and right traveling lever 13, which is configured as an electromagnetic valve operated by 1 and is connected to the control device 10, and operates a traveling control valve (not shown) for driving and operating the left and right crawler traveling devices 4, 4. Switch 1 provided in 14 parts
5, 16 are connected to the control device 10. Switch 1
5 and 16 are set to operate when the traveling levers 13 and 14 are operated to the reverse position r.
When both 3 and 14 are operated to the reverse position r, the control device 10 operates so as to switch the switching valve 9 to the floating position F. The changeover switch 17 between the changeover valve 9 and the control device 10 is an automatic control mode S that is automatically switched to the floating position F in accordance with a reverse operation and a non-control mode that maintains the normal position H regardless of the traveling operation. It switches between E and E. In this embodiment, with the switches 15 and 16, the traveling direction detecting means B includes a return spring 12 and a solenoid 11.
Since the switching mechanism A and the control means are respectively configured by the control device 10, the switches 15 and 16 do not operate when the traveling levers 13 and 14 are in the forward movement position f or the neutral position n, and therefore the switching valve 9 is The state of the normal position H is maintained.

[Other Embodiments] In the above embodiment, the switching valve 9 can be switched to the floating position F regardless of the operating position of the control valve 7, but the switching valve 9 is a good alternative to the pressure oil supply path of the control valve 7. It may be provided on the side. Further, the switching mechanism A is composed of the motor and the speed reducer, or a pressure switch is provided in each of a pair of oil supply and discharge passages to the traveling hydraulic motor, and the traveling direction detecting means B is determined depending on which pressure switch is operated. May be configured. Further, for example, in a transport vehicle in which the dozer 5 is provided at the rear portion of the machine body, the switching valve 9 is switched to the floating position F only when it is in the forward traveling state.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram for driving a dozer.

[Fig. 2] Side view of backhoe

[Explanation of symbols]

 5 Dozer 6 Hydraulic cylinders 6a, 6b Supply / drain passage 7 Control valve 9 Switching valve 10 Control means 14 Drain passage A Switching mechanism B Moving direction detecting means F Floating position

Claims (1)

[Claims] 1. A hydraulic cylinder (6) for driving a dozer (5) up and down, and a pair of oil supply and discharge passages (6a) for the hydraulic cylinder (6).
(6b) A switching valve (9) having a floating position (F) which is short-circuited to each other and is connected to a drain passage (14) to allow free expansion and contraction of the hydraulic cylinder (6).
And a switching mechanism (A) for switching the switching valve (9).
And a traveling direction detecting means (B) for detecting the traveling direction of the airframe.
And the switching mechanism such that the switching valve (9) can be switched to the floating position (F) only when the dozer (5) is in a traveling state other than the forward traveling state. A dozer device for a work vehicle provided with a control means (10) for linking (A) with the traveling direction detection means (B).