JPS5838163Y2 - hydraulic cylinder - Google Patents

Description

[Detailed description of the invention] As shown in FIG.
By alternately supplying high pressure oil to pistons 9 and 010, the piston rod 03 is made to expand and contract with respect to the cylinder 01 to perform work.

In such a hydraulic cylinder, the tip of the piston rod 03 hits the cylinder head 02 at the end of the stroke on the contraction side. Since a large impact is applied to the cylinder head 02, the welded portion of the cylinder head 02 may crack or the structure to which the hydraulic cylinder is attached may be damaged.

Therefore, in order to prevent such damage accidents from occurring,
When the cushion rod 07 is protruded from the tip of the piston rod 03, a cushion oil chamber 08 is formed which allows the cushion rod 07 to fit into the cylinder head 02 in both directions. It rushes into the oil chamber 08 and narrows the drain oil flow path in the gap between the two, thereby increasing the pressure in the pressure chamber 09 and exerting a braking force on the piston rod 03 to alleviate the collision between the piston rod 03 and the cylinder head 02. That's what I do.

However, if the cushion rod 07 and the cushion oil chamber 08 are eccentric, the throttling effect will be reduced, and the annular gap between them must be made small. This may cause the cushion rod 07 and the cushion oil chamber 08 to come into contact with each other, resulting in seizure.

To solve this problem, conventionally, as shown in FIG. 2, an oil hole 020 that communicates with the root opening of the cushion rod 07 is provided in the axial direction, and a multi-stage orifice is installed in this axial oil hole 020. Insert 021 in series and orifice screw 0
These plurality of orifices are fixed within the shaft oil hole 020 at 21'.

Each orifice 021 is provided with an eccentric small hole 022, which is small enough to prevent pressure oil with a flow velocity from flowing straight through the small hole 022 of the succeeding orifice 021 when inserted in series. A plurality of orifices 021 are set so that the holes 022 are alternated.

Furthermore, when the cushion rod 07 enters the cushion oil chamber 08, a cushion ring 013 is interposed between the two to seal the two so that pressure oil does not flow through the annular gap between the two.

The outer diameter of the cushion ring 013 is made smaller than the outer diameter of the annular groove formed in the cushion oil chamber 08, so that the cushion ring 013 can freely move in the radial direction.

By using such means, even if the cushion rod 07 is slightly eccentric with respect to the cushion oil chamber 08, the cushion ring 013 has a degree of freedom in positioning in the radial direction, so that the two can be moved without coming into contact with each other. Sealing is achieved and a stable aperture effect is achieved.

However, the pressure in the pressure chamber 09 during the cushioning action can reach several hundred kg/cwr in some cases, and the flow velocity in the orifice hole 022 caused by this pressure can reach several tens of m/s. Durability problems arise in that the orifice 021 of the succeeding stage is punctured by the jet of pressure oil, and the orifice hole 022 is severely eroded by erosion.

In view of the above circumstances, the purpose of the present invention is to provide a hydraulic cylinder that exhibits a durable cushioning action with stable performance. In a hydraulic cylinder that is equipped with a cushion oil chamber and a cushion oil chamber that performs a cushioning effect by inserting the two at the stroke end, the cushion rod core has a male thread carved on the outer periphery, and the inner periphery is slightly larger than the outer diameter of the male thread. The present invention is characterized by comprising a cushion rod which is screwed onto a cushion sleeve having a female thread having a large root diameter and forms a spiral capillary diaphragm between the male thread and the female thread.

An embodiment of the present invention will be explained with reference to the drawings. Fig. 3 is a longitudinal cross-sectional view thereof, Fig. 4 is an enlarged view showing the threaded portion between the cushion rod core and the cushion sleeve in Fig. 3, and Fig. 5 is a longitudinal sectional view thereof. FIG. 4 is an enlarged view of a screwed portion showing another embodiment different from FIG. 4;

Referring to FIG. 3, 1 is the cylinder, 2 is the cylinder head forming the end of the cylinder 1, 3 is the piston rod to which the piston 4 that slides inside the cylinder 1 is fixed, and 5 is the piston rod that holds the piston 4. 3 is a nut screwed onto the end of the piston rod 3 for fastening; 6 is an oil supply and drain hole drilled in the piston head 2 for supplying and discharging oil in the cylinder 1; and 7 is a piston rod. A cushion rod core 3 is protruded from the tip and has a male thread with an outer diameter d engraved on its surface. 8 is a cushion drilled in the cylinder head 2 to perform a cushioning action in cooperation with a cushion sleeve 14 to be described later. An oil chamber, 9 (ri) is a pressure chamber formed between the right side of the piston 4 and the cylinder head 2, 10 is a pressure chamber formed between the left side of the piston 4 and the cylinder head (not shown), 11 is a supply/exhaust chamber; A piping flange protruding from the oil hole 6, 12(/'i) A piston seal that fits into an annular groove carved on the outer periphery of the piston 4 and seals the gap between the piston 4 and the cylinder 1, 13H cushion oil. The cushion sleeve 1 is fitted into an annular groove carved on the inner surface of the chamber 8.
The cushion ring 14 seals the gap between the cushion rod core 7 and the cushion oil chamber 8, and the inner surface of the cushion ring 14 has a female thread with an outer diameter that screws into a male thread with an outer diameter d cut on the cushion rod core 7. Cushion rod core 7 with a cushion sleeve that exerts a throttling effect due to the gap between the
The cushion rod is screwed onto the cushion rod.

15 is a spiral gap between the female thread of the cushion sleeve 14 and the male thread of the cushion rod core 7, and 19 is an oil groove carved in the abutting end of the cushion sleeve 14.

When such a device is pressed, the piston rod 3 moves from the left to the right and comes near the stroke end, and the cushion sleeve 14 is inserted into the cushion ring 13 of the cushion oil chamber 8.

As a result, the outer periphery of the cushion sleeve 14 and the inner periphery of the cushion oil chamber 8 are sealed, so that pressure oil cannot flow directly from the pressure chamber 9 to the cushion oil chamber 8. It flows through the spiral gap 15 between the male thread of the rod core 7 and the female thread of the cushion sleeve 14 and flows into the cushion oil chamber 8 .

The threaded connection between the cushion rod core 7 and the cushion sleeve 14 can be a triangular thread as shown in FIG. 4, a square thread as shown in FIG. 5, or a thread with another cross section.

Regardless of the cross-section of the thread, by making the outer diameter of the female thread of the cushion sleeve 14 slightly larger than the outer diameter d of the male thread of the cushion rod core 7, the spiral gap 15 forms a long capillary throttle. Therefore, the squeezing effect of oil as a cushion is extremely effective.

Since the cross-sectional area can be relatively large and the flow velocity can be made small, there is no fear of damage caused by the spiral gap 15t/'i erosion or the like.

Since the throttling effect can be achieved by simply changing the outer diameter d of the cushion rod core 7 or the outer diameter of the cushion sleeve 14, the desired throttling effect can be easily achieved.

As described through the embodiments described above, the present invention includes a cushion rod consisting of a cushion rod core with a male thread and a cushion sleeve with a female thread that is screwed onto the cushion rod core, and the cushion rod core and the cushion By appropriately selecting the outer diameter of the thread that engages with the sleeve, a spiral capillary squeeze of pressure oil with a relatively large cross section and relatively low flow rate can provide a durable cushioning effect with stable performance. Since a hydraulic cylinder is obtained, it is extremely useful industrially.

[Brief explanation of drawings]

1 and 2 are longitudinal sectional views showing the cushion portion of a known hydraulic cylinder, FIG. 3 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 4 is a longitudinal sectional view showing the cushion rod core of FIG. FIG. 5 is an enlarged view of the threaded portion with the cushion sleeve, and FIG. 5 is an enlarged view of the threaded portion of another embodiment different from that shown in FIG. 4. 1...Cylinder, 2...Cylinder head, 3...Piston rod, 4...Piston, 5...Nut, 6... ... Oil supply and drainage hole, 7 ... Cushion rod core, 8 ...
・Cushion oil chamber, 9... Pressure chamber, 10...
... Pressure chamber, 11 ... Piping mounting flange, 1
2... Piston seal, 13... Cushion ring, 14... Cushion sleeve, 15... Spiral gap, 19... Oil groove.

Claims (1)

[Scope of utility model registration request] A hydraulic cylinder is equipped with a cushion rod protruding from the end of the piston rod and a cushion oil chamber recessed in the cylinder head, and the cushioning effect is achieved by inserting the two at the end of the stroke. A cushion sleeve having a female thread having a root diameter slightly larger than the outer diameter of the male thread is screwed onto the provided cushion rod core, and a spiral capillary diaphragm is formed between the male thread button and the female thread. A hydraulic cylinder characterized by being equipped with a cushion rod.