JPS64258B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Industrial Application Field The present invention is designed to drain hydraulic oil from a pump in order to prevent further dumping of a cargo box when a cargo box is dumped at a predetermined angle by a hydraulic cylinder. It is used in the field of dump trucks, where the flow is not allowed to flow into the hydraulic cylinder side, but instead is allowed to flow out to the tank side.

(b) Prior Art Generally, in a three-turn dump truck, when a cargo box is dumped at a predetermined angle due to extension of the hydraulic cylinder, the hydraulic pump and the hydraulic cylinder are connected to each other in order to prevent the cargo box from being dumped any further. A bypass control valve is provided in the middle of the piping.

This bypass control valve operates the bypass control valve by utilizing the tilting operation of the hydraulic cylinder, since the hydraulic cylinder tilts in the dumping direction as the hydraulic cylinder extends.

However, since the valve shaft of the bypass control valve is actuated by bringing the surface of the tilting hydraulic cylinder into contact with the link member, the shock or inertia force caused by the contact may cause
The valve hole instantly opens wide and the flow of hydraulic oil from the cylinder side increases. At this time, the pressure on the cylinder side is temporarily low, so the spring force pushing the valve is stronger than the pressure on the cylinder side.
The widely opened valve hole is closed again by the valve, and when the pressure on the cylinder side increases, the valve hole opens and the hydraulic oil in the cylinder flows out through the valve hole into the tank, causing a so-called chattering phenomenon, which reduces the load. This causes the box to vibrate greatly, which transmits a large impact force to each part, causing damage.

(c) Problem to be solved by the invention When the valve shaft is operated by the tilting motion of the cylinder, the impact force and inertia force at the time of contact are alleviated so that the valve hole does not open wide instantly. It is.

(d) Means for Solving the Problems The present invention provides a system in which hydraulic oil from a hydraulic pump flows into a hydraulic cylinder, the hydraulic cylinder is extended to dump a cargo box, and the hydraulic cylinder tilts together with the cargo box. This is a three-turn dump truck in which the arm provided close to the base of the hydraulic cylinder is oscillated, thereby opening the bypass control valve and bypassing the hydraulic oil from the hydraulic pump through the bypass control valve and into the oil tank. In the actuating device, the arm includes a guide tube integrated with the arm, an actuator and an actuator that are slidably housed in the guide tube and whose tip can come into contact with the hydraulic cylinder surface or the valve shaft end surface of the bypass control valve. This invention relates to an actuating device for a three-turn dump truck, which includes a buffer member consisting of an auxiliary spring that is elastically pushed in a direction that causes the tip of the auxiliary spring to protrude from the guide cylinder, and in which the force of the auxiliary spring is weaker than that of the spring of the bypass control valve. .

(e) Embodiment In Fig. 1, 1 is the vehicle body, 2 is a cargo box mounted on the vehicle body 1, and 3, 3... are provided at the front and rear four corners between the vehicle body 1 and the cargo box 2. The hinge part that connects and detaches the boxes 2 is shown.

Reference numeral 4 indicates a hydraulic cylinder that is provided in the center of the vehicle body 1 and is connected between the vehicle body 1 and the cargo box 2. When the hydraulic cylinder 4 is extended, the cargo box 2 is moved around the appropriately selected hinge portions 3, 3. can be dumped backwards or to either the left or right.

In FIG. 2, 5 is a bypass control valve attached to the base of the hydraulic cylinder 4, and 6 is a bypass control valve mounted between the base of the hydraulic cylinder 4 and the bypass control valve 5, supported by a shaft 7 and facing the hydraulic cylinder 4 and the control valve 5. This link member 6 is a link member that can swing freely in the direction.
A buffer member 8, which will be described later and contacts the surface of the hydraulic cylinder 4, is provided at the tip of the upper arm 6a of the link member 6, and the lower arm 6b of the link member 6 is adapted to come into contact with the tip of the valve shaft 9 of the control valve 5. When the hydraulic cylinder 4 is tilted at a predetermined angle, the surface of the hydraulic cylinder 4 abuts against the buffer member 8, thereby operating the bypass control valve 5 via the link member 6.

FIG. 3 shows a bypass control valve 5. The control valve 5 will be explained below. 10 is a cylindrical valve body, and this valve body 10 has an inlet 12 connected to a hydraulic pump 11 and a hydraulic cylinder 4. oil tank 1
An outlet port 14 communicating with the valve body 10 is bored.
A valve chamber 15 is provided inside the valve chamber 15 for communicating the inlet 12 and the outlet 14.

A valve 16 is installed inside the valve chamber 15, and this valve 1
6 is a valve hole 17 provided in the middle of the flow between the inlet 12 and the outlet 14 that can be opened and closed, and the valve chamber 15
A spring 18 provided therein biases the valve 16 in the direction of closing the valve hole 17.

9 is the above-mentioned valve shaft integrated with the valve 16, and the valve body 10
It partially protrudes from the tip.

Next, the buffer member 8 of the upper arm 6a will be explained with reference to FIG. 4. Reference numeral 19 is a guide cylinder integral with the upper arm 6a, and the guide cylinder 19 has a protruding tip and an actuator that comes into contact with the surface of the hydraulic cylinder 4. 20 is slidably installed inside. Reference numeral 21 denotes an auxiliary spring provided between the actuator 20 and an adjustment shaft 22 screwed into the base of the guide tube 19. The force of this auxiliary spring 21 is set to be weaker than the force of the spring 18 constituting the bypass control valve 5. Actuator 20
The distal end portion of the guide tube 19 is made to project from the guide tube 19.

Note that 23 is a tension spring that biases the upper arm 6a toward the hydraulic cylinder 4 side.

The present invention has the above-described configuration. Next, the operation will be explained. When the hydraulic oil from the hydraulic pump 11 is made to flow into the hydraulic cylinder 4 and the hydraulic cylinder 4 is extended, the cargo box 2 is moved to the selected hinge portion 3, Tilt around 3. At this time, the hydraulic cylinder 4 will be tilted in the same direction as the cargo box 2 is tilted.
When the cargo box is tilted at a predetermined angle, the surface of the hydraulic cylinder 4 hits the buffer member 8 at the tip of the upper arm 6a constituting the link member 6, causing the link member 6 to operate. When the link member 6 operates, the lower arm 6b pushes the valve shaft 9 of the bypass control valve 5, opening the valve 16 that had closed the valve hole 17.

By the way, when 16 is released,
First, the actuator 20 is pushed by the tilting of the hydraulic cylinder 4, but since the spring force of the auxiliary spring 21 constituting the buffer member 8 is made weaker than the spring force of the spring 18 constituting the bypass control valve 5, the actuator 20 is pushed. The impact force and inertial force acting on the child 20 are absorbed by the deflection of the auxiliary spring 21.

When the auxiliary spring 21 is further compressed and the spring force becomes stronger than the spring 18, the force from the actuator 20 is transferred to the auxiliary spring 21 and the link member 6.
In order to transmit the information to the valve shaft 9 via the spring 18, the valve 16 is actuated and the valve hole 17 is opened. The oil flows out into the oil tank 13 through the inlet 12, the valve hole 17, the valve chamber 15, and the outlet 14, and the extension of the hydraulic cylinder 4 slowly stops, and the cargo box 2 does not vibrate.

In the link member 6, the upper arm 6a that contacts the surface of the hydraulic cylinder 4 is described in one direction, but the upper arms are provided in three directions, and when each upper arm operates, only the lower The movement is transmitted to the arm.

Further, although the buffer member is attached to the upper arm, it may be attached to the lower arm so that the actuator 20 comes into contact with the end surface of the valve shaft 9.

(f) Effects of the Invention As described above, the present invention provides the arm with a buffer member incorporating an auxiliary spring that is weaker than the spring force of the spring constituting the bypass control valve, thereby reducing the impact force and inertia force acting on the arm. First, the auxiliary spring absorbs the oil, and then the valve is opened, so the valve does not open wide suddenly, and as a result, the amount of hydraulic oil that flows into the oil tank gradually increases, and the hydraulic cylinder stops operating smoothly. , the occurrence of vibration in the packing box is eliminated.

[Brief explanation of drawings]

Figure 1 is a rear view of the three-turn dump truck, Figure 2 is a partial view showing the installation of the bypass control valve at the base of the hydraulic cylinder, Figure 3 is a sectional view of the bypass control valve, and Figure 4 is a sectional view of the bypass control valve.
The figure is a sectional view of the buffer member. 2 is a cargo box, 4 is a hydraulic cylinder, 5 is a bypass control valve, 6 is a link member, 8 is a buffer member, 9 is a valve shaft, 11 is a hydraulic pump, 13 is an oil tank, 1
6 is a valve, 18 is a spring, 19 is a guide cylinder, 2
0 is an actuator, 21 is an auxiliary spring.

Claims (1)

[Claims] 1. Hydraulic oil from the hydraulic pump flows into the hydraulic cylinder, the hydraulic cylinder extends to dump the cargo box, and the hydraulic cylinder, which tilts together with the cargo box, swings an arm provided close to the base of the hydraulic cylinder. In an operating device for a three-turn dump truck, the operating device for a three-turn dump truck is configured to open the bypass control valve and bypass the hydraulic oil from the hydraulic pump to the oil tank through the bypass control valve.
The arm includes a guide tube that is integrated with the arm, an actuator that is slidably housed in the guide tube and whose tip can come into contact with the hydraulic cylinder surface or the valve shaft end surface of the bypass control valve, and a tip of the actuator. An actuating device for a three-turn dump truck, which is provided with a buffer member composed of an auxiliary spring that is elastically pushed in a direction to project from the guide cylinder, and the force of the auxiliary spring is made weaker than the spring of the bypass control valve.