JPH0438094Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a damping device for a hydraulic cylinder for damping impact at the final position of the extension stroke of the hydraulic cylinder.

Conventionally, in this type of shock absorber, as shown in FIG. 5, a support ring is sandwiched between the cylinder head and a locking step on the inner surface of the cylinder, and the shock absorber is supported by a recess in the support ring. A buffer ring supported with an appropriate clearance is provided between the cylinder head and the inner surface of the cylinder head, and a buffer shaft protruding from the outer surface of the piston is fitted into the inner diameter hole of the buffer ring to provide a buffering effect. I was doing it. In this case, since the buffer ring was made of expensive material such as gunmetal, the shape of the buffer ring was made as small as possible, and a support ring made of inexpensive material such as steel was interposed to support the buffer ring. However, the machining of this support ring was complicated and the machining cost was high.

In this invention, the inner diameter part of the buffer ring is made of a low-friction material such as synthetic resin, and the buffer ring is directly supported on the inner surface of the cylinder without using a support ring, so that the buffer ring is made of an inexpensive material. The aim is to make it possible to do so while also reducing the number of processing steps.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

In FIGS. 1 to 4, numeral 1 indicates a hydraulic cylinder, which is constructed as follows. That is, a piston 3 is slidably fitted into the cylinder 5, and is fitted into the inner end of the piston rod 7 and fixed by a nut 9. 11,1
Reference numerals 3 denote a bearing body and an oil seal, which fit on the outer periphery of the piston 3, respectively. Reference numeral 15 designates a buffer shaft portion which is provided adjacent to a shape protruding from the outer surface of the piston 3 (toward the left in FIG. 1, toward the piston rod), and which fits into the piston rod 7 at the inner diameter portion and is attached to the nut 9 together with the piston 3. It is fixed by.
The buffer shaft portion 15 has a conical outer peripheral surface so that the outer end thereof has a small diameter. 17 is cylinder 5
The cylinder head closes the opening of the cylinder via a seal 18, and an oil seal 19, a bearing body 21, and a dust seal 23 are arranged in parallel on the inner diameter portion through which the piston rod 7 passes. Reference numeral 25 denotes a space provided between the cylinder head 17 and the piston rod 7, which opens inward and communicates with hydraulic piping (not shown) via a pressure oil passage 27. Reference numeral 29 denotes a buffer ring provided so as to be able to freely come into contact with the inner surface of the cylinder head 17. The inner surface near the outer periphery is latched so as to be able to come into contact with a locking part 31 provided on the inner diameter surface of the cylinder 5. It is provided with an appropriate play space so that it can freely reciprocate between the inner surface of the cylinder head 17 and the locking portion 31 of the cylinder 5 with an appropriate play space. Reference numeral 33 is an inner diameter portion of the buffer ring 29 and is covered with a friction body 30 made of a low-friction material such as a synthetic resin, into which the buffer shaft portion 15 can be freely inserted with an appropriate clearance. Reference numeral 35 denotes an oil passage passing through the buffer ring 29, which communicates the inside of the cylinder 5 with a gap 37 provided between the outer periphery of the cylinder head 17 and the inner surface of the cylinder 5. Reference numeral 39 is a throttle hole that communicates the cavity 37 and the space 25. 41 and 43 are hydraulic chambers formed inside the cylinder 5, outside and inside the piston 3, respectively.

In the above embodiment, when hydraulic pressure is applied to the hydraulic chamber 43 inside the piston 3, the hydraulic chamber 41 on the opposite side
The oil inside flows from the inner diameter portion 33 through the space 25 and the pressure oil passage 27 to the hydraulic circuit, and the piston 3 moves to the left in FIG. The buffer shaft portion 15 is the inner diameter portion 33
As shown in FIG. 2, the buffer ring 29 is pressed against the inner surface of the cylinder head 17 by hydraulic pressure, and the oil in the hydraulic chamber 41 is released from the clearance around the outer periphery of the buffer shaft 15. It flows into the space 25 , flows into the gap 37 from the clearance around the outer periphery of the buffer ring 29 and the oil passage 35 , and flows into the space through the throttle hole 39 . Therefore, the amount of oil flowing out from the hydraulic chamber 41 is regulated, and the movement of the piston 3 is buffered.
Conversely, when hydraulic pressure is applied to the pressure oil passage 27, the oil flows through the space 25 and the throttle hole 3 at the position shown in FIG.
9. Hydraulic pressure is actuated to flow into the hydraulic chamber 41 through the oil passage 35 and into the hydraulic chamber 41 through the clearance between the outer circumference and inner diameter of the buffer ring 29, and the buffer ring 29 moves as shown in FIG. The piston 3 moves to the position shown in FIG. First, since oil flows into passages other than the throttle hole 39,
The moving speed of the piston 3 becomes faster. Buffer shaft part 15
When the tip of the piston 3 separates from the inner diameter portion 33 of the buffer ring 29, the piston 3 moves rapidly.

Since the present invention has the configuration as described in the claims, it is possible to support a buffer ring made of inexpensive materials without using a support ring, and the number of processing steps can be reduced. Moreover, since the buffer ring automatically responds to the eccentricity of the piston and cylinder, interference force between the buffer shaft and the inner diameter part is eliminated, and since the inner diameter part is made of a low-friction material, the buffer ring automatically responds to the eccentricity of the piston and cylinder. It is possible to reduce wear on the shaft portion and the inner diameter portion. In addition, on the forward path where buffering is performed, the speed of the piston is regulated by the throttle hole, but on the return path in the opposite direction, oil flows through passages other than the restrictor hole, so the piston speed increases, improving work efficiency. be.

Figure 5 shows the main parts of the conventional example, including the cylinder head 17 and the locking step 4 on the inner surface of the cylinder 5.
A support ring 47 is sandwiched between the support ring 4 and
A buffer ring 49 is provided in a recessed portion within the buffer ring 7 . 51
53 is a communication hole provided in the support ring 47, and 53 is a buffer ring 29.
This is a throttle hole that communicates the clearance on the outer periphery of the hydraulic passage 27 with the hydraulic passage 27.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be implemented in other embodiments as well. Further, the symbols shown in the claims do not limit the technical scope of the present invention.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of one embodiment of the present invention;
3 and 4 are side sectional views of the main parts showing the operating state, respectively, and FIG. 5 is a side sectional view of the main parts of the conventional example. Explanation of the symbols representing the main parts of the drawing, 3...
Piston, 5... Cylinder, 15... Buffer shaft portion, 17... Cylinder head, 27... Hydraulic passage, 29... Buffer ring, 31... Locking portion, 33...
Inner diameter part, 35...oil passage, 39...throttle hole.

Claims (1)

[Scope of utility model registration request] A cylinder 5 has a piston 3 which is integrated with a rod 7 and has a stepped concentric opening at the end thereof, and a cavity 37 is interposed between the opening of the cylinder 5 and the rod 7. 7, a cylinder head 17 which closes the cylinder 5 with a space 25 interposed therebetween, and a locking surface 31 on the inner diameter surface of the cylinder 5 which is substantially parallel to the inner surface of the cylinder head 17 and which is substantially parallel to the inner surface of the cylinder head 17; A cylindrical space formed by the outer peripheral surface of the rod 7, a buffer ring 29 movable within the space with an appropriate play in the axial and radial directions, and an inner surface of the buffer ring 29. A friction body 30 made of a low-friction material is provided on the piston 3, and a buffer shaft portion 15 with a conical tip is provided so as to protrude toward the rod 7 side of the piston 3 so as to be able to fit into the inner diameter portion of the friction body 30. and a pressure oil passage 27 provided in the cylinder head 17 and communicating with the hydraulic pipe at one end and communicating with the space 25 at the other end.
and a space 25 provided in the cylinder head 17.
an oil passage 35 that axially penetrates the buffer ring 29 so as to communicate the gap 37 with the piston 3 side space of the buffer ring 29;
A shock absorber for a fluid pressure cylinder consisting of.