JPS6137842Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a cushion adjustment device in a hydraulic cylinder.

A conventional cushion adjusting device of this type is shown in FIG. 3, and its overall structure will first be explained. 1 is a hydraulic cylinder, etc., 2 is an operating piston that moves the operating cylinder chamber 3, 4 is a small cushion piston protruding from the operating piston, and 5 is a small cushion provided on the cylinder cover 6 opposite to this. A cylinder chamber 7 is a passage communicating with the small cylinder chamber 5;
8 is a passage communicating with the working cylinder chamber 3. A flow control chamber 9 is provided in the cylinder cover 6 at the intersection of both passages 7 and 8, and a flow control rod 11 is screwed into the perforated plug 10 screwed onto the cylinder cover 6 so as to be freely adjustable in the axial direction. and the flow control rod 1
a perforated poppet valve 13 having a perforated portion 12 provided coaxially with the control rod 11 so as to be guided by the perforated poppet valve 1; and a pressing spring 1 for pressing the perforated poppet valve 13 against a valve seat 14.
5 is accommodated in a flow control chamber 9, and the flow control rod 11 is provided with a triangular pyramidal or semiconical V-groove 16 projecting from the end of the rod 11, the diameter of which gradually decreases in the axial direction. Furthermore, a seal ring 17 is provided on the inner wall of the perforated portion of the perforated plug 10 to hold the oil (air) chamber of the flow rate control chamber 9. 1
8 is a rock nut.

The operation of the above conventional device is as follows. When the working piston 2 moves to the right in the figure, the pressure oil in the working cylinder chamber 3 passes through the small cylinder part 5 and is discharged from the supply/discharge port 19, but the small cushion piston 4 rushes into the small cushion cylinder chamber 5. Then, since the outlet of the pressure oil in the working cylinder chamber 3 is blocked, the pressure oil flows through the passage 8 and the flow control chamber 9 as shown by the arrow.
The hydraulic oil is sent to the small cylinder chamber 5 via the passage 7, and by controlling the flow rate of the pressure oil in the flow rate control chamber 9, the actuating piston 3 receives flow resistance and exerts a cushioning (buffering) effect. In addition, when the operating cylinder 2 operates in the left direction in the figure, the port 19
The perforated poppet valve 13 is moved upward against the pressing force of the pressing spring 15 by the pressure oil from the cylinder, and the passages 7 and 8 are brought into communication with each other. Pressure oil is sent to press the actuating piston 2.

By the way, the flow rate control for causing the operating cylinder 2 to exert a cushioning action is performed using a conical V-groove 1 opened between the flow rate control rod 11 and the perforated poppet valve 13.
This is done by increasing or decreasing the opening area of the V-groove 16, and as is clear from the illustrated state, if the flow rate control rod 11 is moved upward in the figure, the opening area of the V-groove 16 increases.
Therefore, by increasing the moving speed of the operating cylinder 2 and adjusting it downward in the figure, the opening area of the V-groove 16 is reduced, and the moving speed is slowed down.

This conventional device is superior in that it is configured to perform the check valve action and the throttle valve action on the same axis.
However, there are the following difficulties.

○B As mentioned above, the V groove 1 is installed in the small diameter flow control rod 11.
6, the cross-sectional area of the V-groove is naturally small and it is not possible to obtain a large flow rate of throttle flow.Also, since the V-groove 16 is nozzle-shaped, the flow rate is easily affected by the viscosity of the pressure oil, so it is difficult to start using it. If the temperature changes during use, it is necessary to readjust the aperture amount.

○B In order to provide the conical V-groove 16 whose diameter gradually decreases in the axial direction on the flow control rod 11, extremely special machining is required, which increases the manufacturing cost.

○C The perforated poppet valve 13 is designed to move up and down guided by the flow control rod 11, but the V-groove 1
When the control rod 11 is moved upward in order to increase the opening area of the poppet valve 6, as can be seen from the diagram, the poppet valve 13 with the hole almost comes out of the control rod 11, and the movement of the poppet valve 13 with the hole becomes almost impossible. is extremely unstable.

○D As mentioned above, since the conical V-groove 16 serving as the throttle part must be provided long in the axial direction of the flow control rod 11, the flow control rod 11 must be moved and adjusted considerably in the axial direction in order to adjust the flow rate. First, because of this, there is a risk that the flow control rod 11 may come out of the flow control chamber 9, and an unexpected accident may occur if the flow control rod 11 jumps out of the flow control chamber 9, which is loaded with large pressure. .

○E When used in a hydraulic cylinder, air must be vented separately.

○F It is extremely difficult to provide a groove for the seal ring 17 on the inner wall of the perforated portion of the perforated plug 10 in terms of processing.

Further, another example of a conventional flow rate control device is disclosed in Japanese Utility Model Application No. 47-29087. In this method, the pilot valve is delivered so that it can be moved a certain distance within the valve cylinder that constitutes the check valve, and the distance between the conical part provided at the lower end of the pilot valve and the circumference of the hole provided at the bottom of the valve cylinder is This attempts to adjust the amount of aperture based on the gap. However, according to this, it is not possible to adjust the amount of movement of the pilot valve from the outside, so when adjusting the cushion,
It is very difficult to disassemble the device, adjust the amount of movement, and reassemble it many times. Further, since the constriction part is the gap between the periphery of the hole and the conical part, it is easily affected by viscosity, and since the gap is circumferentially elongated, there is a problem in that dust tends to accumulate there.

The present invention solves these problems and provides a cushion adjustment device that is easy to adjust, is not easily affected by the viscosity of pressure oil, and is optimal for hydraulic cylinders.

Hereinafter, an embodiment of the present invention will be described. Those with the same structure as the conventional example shown in FIG. An axially adjustable flow rate control rod 21 is screwed onto a perforated plug 20 screwed in an oil-tight manner, and a perforated poppet valve 2 is attached to the control rod 21.
The poppet valve 22 is fitted loosely so as to be freely slidable, and the poppet valve 22 is pressed against the valve seat 24 by a pressing spring 23. A control rod 2 is attached to the perforated poppet valve 22 so that it can move up and down while being guided by the aforementioned control rod 21.
1 and a perforated portion 25 which communicates with the cushion small cylinder chamber side passage 7;
and an opening 26 communicating with the working cylinder chamber side passage 8, and by adjusting the flow rate control rod 21 loosely fitted in the perforated part 25 in the axial direction, the rod 21 faces the perforated part 25. The opening area of the opening 26 is increased or decreased by the tip 21' of the control rod 21, and a constricted portion 27 is formed between the tip 21' and the opening 26.

Furthermore, an air vent 28 is bored through the upper part of the flow control rod 21 to communicate the flow rate control chamber 9 with the outside air, and the air vent 28 is normally connected by a set screw 30 via a steel ball 29 that closes the upper end surface of the air vent 28. It is cut off from the outside air. Further, a large diameter portion 31 is formed on the outer circumference of the control rod 21, and a small groove 3 is formed on the outer circumferential surface of the control rod 21.
A seal ring 33 is fitted to the flow rate control chamber 9.
A male threaded portion 34 is formed above the large-diameter portion 31 to maintain oil-tightness inside the holed plug 20.
Therefore, when the upper end surface 31' of the large diameter portion 31 comes into contact with the female threaded portion 35 of the perforated plug 20, the flow control rod 21
The large diameter portion 31 controls the upper limit position of the control rod 21 to prevent it from coming off. Note that 36 is a stopper that comes into contact with the end face of the perforated plug 20, and defines the upper limit position of the perforated poppet valve 22.

Therefore, according to the present invention, when the actuating piston 2 reaches the cushion operating position, the pressure oil in the actuating cylinder chamber is sent to the small cylinder part 5 through the passage 8, the opening 26, the constricted part 27, the perforated part 25, and the passage 7. In this case, the amount of throttling is determined by adjusting the flow rate control rod 21 and increasing or decreasing the opening area between its tip 21' and the open channel 26.

According to the present invention, the following effects are achieved.

The throttle part 27 is the tip part 21' of the flow control rod 21.
Since the flow control rod 21 itself is formed between the flow control rod 21 and the opening 26 of the perforated poppet valve 22, no special precision machining is required for the flow control rod 21 itself, and therefore, the product can be manufactured at low cost.

The flow rate of the throttle flow is determined by the opening area of the opening 26 of the perforated poppet valve 22 and the cross-sectional area of the control rod 21, and since the entire cross-sectional area of the control rod 21 is used to adjust the throttle opening, the flow rate is In addition, since the constriction part 27 is orifice-shaped, it is less affected by viscosity, is less likely to be clogged with dirt, and can be easily adjusted from the outside.
The cushion can be adjusted very easily.

Even when the constriction part 27 is fully opened, the perforated poppet 22 is not connected to the control rod 2, as is clear from the illustrated state.
1 with a sufficient length, its operation is stable.

Since the adjustment movement stroke of the flow rate control rod 21 is simply between the diameters of the open circuit 26 of the perforated poppet valve 22, the stroke can be reduced; in other words, it is possible to shorten the control rod 21;
Furthermore, there is little risk of the flow control rod 9 coming off.

In conjunction with the above, the flow control rod 21 is simply formed into a rod shape and does not require any precision machining on its outer circumferential surface, so the axial length of the control rod 21 is simply changed in response to changes in the axial dimension. There is no need to change other components. The number of common parts can be increased accordingly, which is advantageous for mass production.

Even if the pressure spring 23 is broken, the chamber housing the pressure spring 23 is located outside the pressure fluid flow path, so the broken spring will not enter the pressure fluid flow path, making maintenance and inspection easy. It is.

Since the air vent that communicates the flow control chamber with the outside air is built into the flow control rod in a sealed and removable manner, there is no need to provide a separate air vent, making it possible to manufacture a hydraulic cylinder in a smaller size and at a lower cost, and also to reduce maintenance costs. Easy to do.

Furthermore, since there is a margin in the length of the flow control rod 21 in conjunction with the above, a large diameter portion 31 with a slightly larger diameter is provided in this margin, and a small groove 32 for a seal ring is provided on the outer circumferential surface of the rod. Since the large diameter portion 31 defines the upper limit of the flow rate control rod 21, the control rod 21 can be completely prevented from coming off.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view showing an embodiment of this invention, FIG. 2 is an enlarged vertical sectional view of the same essential part, and FIG. 3 is a longitudinal sectional front view of a conventional example. 1... Working cylinder, 2... Working piston, 3
...Operating cylinder chamber, 4...Small piston for cushion, 5...Small cylinder chamber for cushion, 6...
Cylinder cover, 7... Passage on the small cylinder chamber side for the cushion, 8... Passage on the operating cylinder chamber side, 9...
Flow rate control chamber, 21...Flow rate control rod, 22...Poppet valve with hole, 23...Press spring, 24...Valve seat, 2
5... Perforated part, 26... Open circuit, 27... Throttled part,
28...Air vent, 31...Large diameter part, 34...Male thread part.

Claims (1)

[Claims for Utility Model Registration] 1. A flow rate control chamber is provided between a passage connected to the operating cylinder chamber and a passage communicating with a small cushion cylinder chamber, and a male threaded portion is provided at one end within the flow rate control chamber. a flow rate control rod which can be freely adjusted in the axial direction by rotating it from the outside, and a passage installed coaxially with the flow rate control rod so as to be guided by the flow rate control rod and in a passage on the side of the small cylinder chamber for the cushion. A perforated poppet valve having a perforated part communicating with the perforated part and a spring for pressing the perforated poppet valve against a valve seat are accommodated, and the perforated poppet valve further includes a passage on the side of the operating cylinder chamber and the perforated part. By providing a communicating open channel and adjusting in the axial direction a flow control rod that is loosely fitted into the perforated portion, the opening area of the open channel facing the perforated portion is increased or decreased, and a constricted portion is formed here. A cushion adjustment device for a hydraulic cylinder, wherein the air vent for communicating the flow rate control chamber with outside air is removably built into the flow rate control rod. 2. A large diameter part is provided on the outer peripheral surface of the flow control rod, a small groove for a seal ring is carved in this, and the upper limit of the flow control rod is defined by the large diameter part. A cushion adjusting device according to claim 1 of the utility model registration claim.