JPH0347000A - Control valve for tilt cylinder - Google Patents

Abstract

PURPOSE:To prevent response delay by forming a lead-in passage between a damper chamber and a pump port at a plunger itself as well as providing the passage with a check valve for impeding the flow to the port and making the width of a collar part large, thereby restricting the inflow/outflow of oil to/from the damper chamber as much as possible. CONSTITUTION:When a spool 12 is tilted forward, a tilt lock plunger 13 is displaced into a communicating position against a spring 16. Operating oil is led into a damper chamber 14 from a pump port 4 through a lead-in passage 27 formed at a plunger 13 itself. The displacement of the plunger 13 can be thereby performed promptly so as to prevent response delay. A check valve 28 is provided at the passage 27 to impede the contraflow of the operating oil in the damper chamber 14 and avoid the influence of the pressure fluctuation of the port 4, thus suppressing the variation of the plunger 13. At the time of engine stop, the operating oil in the damper chamber 14 is returned to a tank port 8 through a slight gap between a wide collar 17 and the inner surface of a spool hole, and the plunger 13 is returned to the original position by the spring 16.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a tail control valve for controlling a tilt cylinder for rearward tilting of a forklift mast Iyj. The present invention relates to a Teltlock plunger that is assembled within the tilt spool to limit forward tilting speed to li.

(Prior Art) Figures 3 and 4 show a conventional till-silling oil control valve with a tilt-lock plunger. The valve body 1 includes a center bypass 2 that communicates with a discharge pipe of a hydraulic pump 9, left and right pump bows 1-3.4 that communicate with the center bypass 2 via check valves (not shown), and a bottom of a tilt cylinder 10. It includes a cylinder bottom bow h5 communicating with the side oil chamber, a cylinder rod boat 6 communicating with the rod side oil chamber of the air cylinder 10, and left and right tank boats 7.8 communicating with the tank 11. A tilt spool 12 is attached to the valve body 1 so as to be able to slide in the axial direction, and is normally held at the neutral position shown in FIG. 3 to close the bottom boat 5 and rod boats 1 and 6 of the tilt cylinder 10. are doing.

Therefore, the tilt lock plunger 13 for increasing the tilting speed υIII when the mast is tilted forward is connected to the tilt spool 1.
2 so as to be slidable in the axial direction. The position of the tilt lock plunger 13 is controlled by the pump pressure in the damper chamber 14 acting on one end in the axial direction and the spring 16 acting on the other end. Although it is held at the left blocking position shown in FIG. 3, when the tilt spool 12 is operated to the forward tilting side (to the right side in the drawing) while the engine is running, the pressure in the damper chamber 14 overcomes the pressing force of the spring 16. FIG. 4 shows a state in which the tilt spool 12 has been operated to the forward tilting side and the tilt lock plunger 13 has been displaced to the communication position δ.

In other words, when the tilt spool 12 is tilted forward while the engine is running, the pump port 3 on the left side communicates with the cylinder bottom boat 5, so the hydraulic fluid discharged from the hydraulic pump 9 flows into the cylinder 10. Sent to the bottom room. At this time, a part of the hydraulic oil passes through the through hole 15 of the tilt spool 12 from the right pump port 4 and enters the outer peripheral space 20 between the center flange 18 and the left flange 17 of the tilt lock plunger 13. This J: Rik=&
; flows into the damper chamber 14 through the gap S between the outer peripheral surface of the dildo 17 and the inner peripheral surface of the dildo 1 to spool hole, and displaces the dildo lock plunger 1713 against the spring 16 to the communicating position.

At this time, a part of the hydraulic oil that has flowed into the outer peripheral space 20IC flows into the spring housing chamber 22 through a passage 21 formed at the center of the axis of the tilt lock plunger 13, and further flows into a passage provided in the tilt spool 12. It flows out through the hole 23 to the tank boat 8 on the right side of the figure. This is done for the purpose of suppressing rapid displacement of the tilt lock plunger 13.

As a result of the displacement of the tilt-lock plunger 13 to the communicating position, the outer circumferential space 24 between the center flange 18 and the right flange 19 of the tilt-lock plunger 13 is formed in the small hole 25, 26 in the tilt spool 12. Since the cylinder rod boat 6 and the tank boat 8 on the right side are communicated through the cylinder rod boat 6 and the tank boat 8 on the right side, hydraulic oil in the rod chamber flows out to the tank 11, the tilt cylinder 10 is operated to extend, and the mast is tilted forward. In this case, the mast is always subject to a forward tilting load and tends to tilt rapidly, but as mentioned above, the flow of hydraulic oil on the outflow side is restricted by the small holes 25 and 26. The forward tilting speed of the mast is suppressed to an appropriate speed. In other words, the tilt-lock plunger acts to control the forward tilt of the mast to an appropriate speed. Once the tilt lock plunger 13 is displaced to the communication position, even if the tilt spool 12 is returned to the neutral position or operated to the rear tilted position, the damper chamber 1
4 is not communicated with the tank side, so it is held in the communicating position.

On the other hand, when the engine is stopped, the pump pressure in the pump bows 1 and 4 disappears as the hydraulic pump 9 stops, so that the hydraulic oil in the damper chamber 14 flows into the outer peripheral surface of the left flange 17 and inside the tilt spool hole. Pump bow 1 passes through the gap S with the surrounding surface
-4, and the tilt lock plunger 13 is connected to the spring 1.
6, the mast is returned to the initial blocking position δ, preventing the hydraulic oil in the rod side oil chamber of the tilt cylinder 10 from flowing out, and holding the mast from the corner in the forward tilting direction. In other words, it prevents the square 1- from swinging or running on its own (falling forward).

(Problem to be Solved by the Invention) By the way, in the case of the above-mentioned conventional tilt-lock cylinder control valve, the tilt-lock plunger 1
3 is controlled depending on the gap S between the outer circumferential surface of the left flange 17 and the inner circumferential surface of the tilt spool hole. Therefore, when the gap S is small, the operation into the damper chamber 14 is controlled. The inflow of oil is restricted, causing a delay in the operation of the tilt-lock plunger 13, causing a problem in which the mast cannot immediately start tilting forward.On the other hand, when the gap S is large, the tilt-lock plunger 13 is forced to close to the spring 16. It vibrates due to the reaction, and the pressure at the pump port 4 becomes unstable, and the opening and closing operations are repeated between the pump port 4 and the cylinder rod boat 6, making it difficult to follow the pressure and flow m, causing the mast to vibrate. There is a problem. It is technically very difficult to set the gap S so that such a two-year condition does not occur.

Therefore, in view of the above problems, the present invention aims to provide a tilt cylinder control valve having an effective structure for preventing activation delays and vibrations when the mast is tilted forward.
That purpose.

(Means for Solving the Problems) In order to solve the above problems, the present invention is configured as follows.

It is slidably inserted in the tilt spool in the axial direction to control the tilting speed when the mast is tilted forward, and is controlled by the pump pressure in the damper chamber that acts on one end in the axial direction and the spring that acts on the other end. , a control valve for a tilt cylinder equipped with a tilt lock plunger that is displaced between a position δ that communicates the rond side oil chamber of the tilt cylinder with the tank and a position that blocks it, wherein the damper An introduction passage is formed to communicate the chamber and the pump port, and the same passage is provided with a check valve for controlling the flow from the damper chamber to the pump port (m+).

In addition, the width of the flange formed on the tilt lock plunger to partition the damper chamber and the gap between the outer circumferential surface of the flange and the inner circumferential surface of the tilt spool hole are such that oil can flow into and out of the damper chamber. is set to be limited to

Specifically, while the flange width is set larger than before, it is desirable to set the gap between the outer circumferential surface of the flange and the inner circumferential surface of the tilt spool hole to be narrower than before.

(Function) According to the tilt cylinder control valve configured as described above, when the tilt spool is operated to the forward tilt side, the hydraulic oil flowing from the pump board is prevented from returning from the passage formed in the tilt lock plunger itself. It flows into the damper chamber through the valve and displaces the tilt-lock plunger to the communicating position against the spring. In this candlestick,
It is possible to set the size of the introduction passage so that the tilt-lock plunger is quickly displaced without any delay in actuation, and even though the introduction passage is sufficiently wide, the pressure in the damper chamber is reversed. Due to the presence of the stop valve, the vibration of the tilt-lock plunger is suppressed because it is held constant without being affected by the reaction of the spring or the pressure fluctuation of the pump port.

(Example) Hereinafter, an example of the present invention will be specifically described based on FIGS. 1 and 2.・The same components as those in the prior art described above are designated by the same reference numerals and their explanations will be omitted.

FIG. 1 shows the tilt spool 12 in the neutral position and the tilt lock plunger 13 held in the initial shutoff position by the spring 16, and FIG. 2 shows the tilt spool 12 in the forward tilted position; A state in which the tilt lock plunger 13 is displaced to the communication position t against the force of the spring 16 is shown.

As shown in the figure, on the left side of the tilt-lock plunger 13, an introduction passage 27 for introducing hydraulic oil into the damper chamber 14 is formed at the center of the axis, and an inlet 27a of the same person passage 27 is located at the left flange. 17 and the central flange 18 into the outer circumferential space 20, and the outlet 27i) is opened into the damper chamber 14.

A Bueck ball 28 as a check valve is incorporated in the introduction passage 27 to prevent oil from flowing out from the damper chamber 14 side to the outer circumferential space 20 side.

Note that 29 is a plug.

On the other hand, the gap S between the outer peripheral surface of the left flange 17 that partitions the damper chamber 14 and the inner peripheral surface of the Diltsbourg hole is conventionally 15 to 3.
What used to be 0μ (microns) has been narrowed to 10-20μ, and furthermore, the width of the left flange 17, which was previously 1mA, has been reduced to 3! NR is increased to J3, thereby making it possible to restrict the flow of oil between the outer circumferential surface of the left flange 17 and the inner circumferential surface of the tilt spool hole as much as possible.

Therefore, when the tilt spool 12 is operated to the #J inclined side shown in FIG.
The hydraulic oil flowing into the check ball 2 of the introduction passage 27
8 and flows into the damper chamber 14, and moves the plunger 13 against the spring 16 to the communication position shown in FIG. It is moved to a position where the portion 18 and the right flange portion 19 are communicated through the outer circumferential space 24 and the small holes 25 and 26. Therefore, the hydraulic oil from the hydraulic pump 9 is sent to the bottom oil of the tilt cylinder 10 via the pump port 3 on the left side of the figure and the cylinder bottom boat 5, while the hydraulic oil in the rod side oil chamber is leaked to the tank 11. The tilt cylinder 10 is extended and the mast is tilted forward.

Therefore, in this embodiment, the hydraulic oil is introduced into the damper chamber 14 through the introduction passage 27 that covers the check ball 28 formed on the tilt-lock plunger 13 itself, so that the outer peripheral surface of the left flange 17 Unlike the conventional method in which hydraulic oil is introduced through the gap S between the inner periphery of the tilt lock plunger 13, it is now possible to set the area of the introduction passage 27 so that the tilt lock plunger 13 is quickly displaced. It is possible to eliminate the possibility that the lock plunger 13 is about to operate. In addition, a check ball 28 is provided in the introduction passage 27 to prevent the backflow of the hydraulic oil in the damper chamber 14, thereby avoiding the reaction of the spring 16 or If of the pressure variable axis of the pump bow 1-4, and moving the tilt lock plunger. 13 vibrations can be suppressed,
The outflow of hydraulic oil from the cylinder rod boat 6 to the tank 11 is stabilized, and the tilt cylinder 10 can be operated smoothly.

When the engine is stopped, the hydraulic oil in the damper chamber 14 returns to the tank boat side through a small gap S between the outer peripheral surface of the left flange 17 and the inner peripheral surface of the tilt spool hole, and the tilt lock plunger 13 is moved by the spring 16. By returning the mast to its initial position by 5 m, the rod-side oil chamber of the tilt cylinder 10 and the tank 11 are blocked off, thereby preventing the mast from swinging or self-propelling (falling forward), which is always under load on the forward-tilting side. .

Note that it is desirable to set the inlet 27a of the introduction passage 27 smaller than the inlet 21a of the passage 21 leading to the spring storage chamber 22 within a range that does not cause delay in operation. This is effective in suppressing vibration of the tilt lock plunger 13.

(Effects of the Invention) As detailed above, according to the present invention, it is possible to provide a control valve for a tilt cylinder that can prevent production delays and vibrations, and can provide good response and stable operation. It is something. In addition, since it is possible to replace conventional control valves with a tilt lock plunger attached to a tilt spool as a tilt spool assembly, problems such as operation delays and vibrations can be avoided not only in newly manufactured vehicles. It can also be easily applied to existing vehicles that have the following characteristics.

[Brief explanation of drawings]

FIGS. 1 and 20 are sectional views showing embodiments of the tilt cylinder control valve of the present invention, and FIGS. 3 and 4 are sectional views showing conventional tilt cylinder control valves, respectively. 1... Valve body 3.4... Pump port 9... Hydraulic pump 10... Dill 1 to cylinder 12... Tilt spool 13... Tilt lock plunger 14... Damper chamber 16...・Spring 17.18
．． 19...Tsubabe

Claims (1)

[Claims] It is slidably inserted in the tilt spool in the axial direction to control the tilting speed when the mast is tilted forward, and the pump pressure in the damper chamber acts on one end in the axial direction, and the spring acts on the other end. Therefore, in a control valve for a tilt cylinder equipped with a tail lock plunger that is displaced between a position where the rod-side oil chamber of the tilt cylinder communicates with the tank and a position where it is closed, the damper chamber and the pump port are communicated with each other. In addition to forming an introduction passage in the tilt-lock plunger itself, the introduction passage is provided with a check valve to prevent the flow from the damper chamber to the pump port. A control valve for a tilt cylinder, in which the width of a formed flange and the gap between the outer circumferential surface of the flange and the inner circumferential surface of a tilt spool hole are set so that the flow of oil into and out of a damper chamber is restricted as much as possible.