JPH0743456Y2 - Cushion device for hydraulic cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a cushion device for cushioning a shock at a stroke end portion of a piston.

(Prior Art) A conventional example will be described with reference to FIGS. 4 and 5. FIG. 4 is a half-cut sectional view showing the structure of the reciprocating device, in which reference numeral 1 is a housing. A piston rod 3 is accommodated in the housing 1 so as to be slidable in the left-right direction in the drawing. A piston 7 is attached to the piston rod 3 via a cushion ring 5. The position of the piston 7 is fixed by a nut 10. A groove 9 is formed in the cushion ring 5 as shown in FIG. The groove 9 is deep and wide toward the left in the figure. A cushion ring 5 is attached to the housing 1.
A hole 11 is formed so that The hole 11 and the groove 9 are combined to form a variable diaphragm. In addition,
Reference numerals 15 and 17 in the figure are seal rings.

According to the above configuration, at the end of the stroke, the cushion ring 5 enters the hole 11 of the housing 1 from the right direction in the figure. At this time, oil in the cushion chamber 13 between the piston 7 and the housing 1 flows out from the inflow / outflow port 2 through the groove 9 formed in the cushion ring 5 as shown by an arrow a in the figure. As the degree of fitting of the cushion ring 5 increases, the flow passage area of oil is narrowed down, and the fluid resistance gradually increases. As a result, the buffer function is exerted. Finally, the end of the stroke is reached at a position where the oil flow path is completely closed, that is, in a state where the length shown by l in the figure remains.

(Problems to be Solved by the Present Invention) According to the above conventional configuration, there are the following problems. As described above, the stroke end is reached when the length l of the end of the cushion ring 5 is left, but at this time, the oil in the cushion chamber 13 is in a sealed state, and thus the piston 7 is not drawn in this state. When an external force in the direction indicated by the middle arrow b acts, the oil in the cushion chamber 13 is compressed and the pressure in the cushion chamber 13 becomes high. Due to such increase in pressure, there are problems that the cylinder tube 14 expands and the seal rings 15 and 17 protrude.

An object of the present invention is to provide a cushion device that can alleviate an increase in pressure in a cushion chamber and prevent damage to various members such as a housing.

(Means for Solving the Problem) This invention is to fit a housing, a piston rod reciprocally housed in the housing, a piston attached to the piston rod, and an outer circumference of the piston rod. At the same time, the cushion ring has a groove formed on the outer circumference, the groove having a depth that gradually decreases in the axial direction, and the cushion ring enters the hole formed on the housing side at the stroke end portion of the piston. It is premised on a cushion device of a hydraulic cylinder that gradually throttles a variable throttle formed by combining with the groove.

Then, on the premise of the above device, the present invention is characterized in that a communication space is formed between the cushion ring and the piston rod, a ring member is provided in the communication space, and an orifice is formed in the ring member. Have.

(Operation of the Invention) At the end of the stroke of the piston, oil is trapped in the cushion chamber.
Escaped through the next route. That is, the oil in the cushion chamber is released through the communication passage between the cushion ring and the piston, the communication passage of the ring member, and the communication space between the cushion ring and the piston rod. Therefore, even if an external force acts, the fluid in the cushion chamber is not compressed and the pressure does not rise more than necessary, and the soundness of each member is reliably maintained.

(Embodiment of the Present Invention) A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2. The same parts as those of the prior art are designated by the same reference numerals and the description thereof will be omitted.

A communication passage 103 is formed between the cushion ring 101 and the piston rod 3 of this embodiment, and a communication passage 105 is also formed between the piston ring 7 and the piston 7. And
A communication passage 102 is held between the cushion ring 101 and the piston rod 3. An annular groove 107 is formed at a substantially intermediate position of the communication space 102. A ring member 109 is attached to the annular groove 107. This ring member 109
Has a communication passage that allows the cushion chamber 13 and the inflow / outflow port 2 to communicate with each other. For example, as shown in FIG.
An orifice 111 is formed on the cushion chamber 13 side, and
An orifice 113 is formed on the inflow / outflow port 2 side. Other than that, FIG. 2 (b) and FIG. 2 (c)
The configuration shown in FIG.

The operation will be described based on the above configuration. At the end of the stroke, it stops in the state shown in FIG. When an external force acts in the direction of arrow b in this state, the oil in the cushion chamber 13 is pushed out and discharged from the inside of the cushion chamber 13 via the communication passage 105, the orifice 111, the orifice 113, and the communication passage 103. Therefore, it is possible to prevent the situation in which the oil is compressed and the pressure is increased in the cushion chamber 13, and the members such as the housing 1 are expanded and damaged.

According to this embodiment, the following effects can be obtained.

First, even if an external force is applied at the end of the stroke, it is possible to prevent the pressure in the cushion chamber 13 from rising and prevent damage to the housing 1 and the seal rings 15 and 17 due to the pressure increase.

Further, each orifice 11 of the ring member 109 in the present embodiment
Since the processing of 1 and 113 is relatively easy and the quality is constant, the cushioning function of the cushion ring 101 is less affected.

The escape channel according to the present embodiment is the cushion ring 101.
Of course, it is configured so as not to impair the buffering function of.

Next, a second embodiment will be described with reference to FIG. This is one in which an annular groove 107 is formed on the cushion ring 101 side and a ring member 109 is attached thereto, and the same effect as in the case of the first embodiment can be obtained.

(Effects of the Present Invention) As described in detail above, according to the device of the present invention, the compression of the fluid in the cushion chamber due to the action of the external force at the end of the stroke can alleviate the increase in pressure and prevent damage to each member.

[Brief description of drawings]

1 and 2 are views showing a first embodiment of the present invention,
1 is a half cutaway view, FIG. 2 is a perspective view showing the structure of a ring member, FIG. 3 is a half cutaway view showing the structure of a second embodiment, and FIGS. 4 and 5 show conventional examples. FIG. 4 is a half-cut sectional view, and FIG. 5 is a perspective view of a cushion ring. 1 ... Housing, 3 ... Piston rod, 7 ... Piston,
101 ... Cushion ring, 103, 105 ... Communication groove, 107 ... Annular groove, 109 ... Ring member, 111, 113 ... Orifice.

Claims (1)

[Scope of utility model registration request] 1. A housing, a piston rod reciprocally incorporated in the housing, a piston attached to the piston rod, and a cushion ring adjacent to the piston and fitted to the outer circumference of the piston rod. In a cushion device for a hydraulic cylinder, which is provided with a cushion ring and is formed so that the clearance between the cushion ring and the hole on the housing side becomes gradually smaller toward the piston in the stroke end state where the cushion ring enters the hole formed on the housing side. A cushion device for a hydraulic cylinder, wherein a communication space is formed between the cushion ring and the piston rod, a ring member is provided in the communication space, and an orifice is formed in the ring member.