JPS6110028Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a compression type single cylinder shock absorber, and the relationship between the piston rod and the sealing member is such that the piston rod is sealed only at the maximum extension of the piston stroke, and is sealed to the piston rod so that liquid leaks at other positions. In the initial state of the shock absorber, the piston rod is sealed with the large diameter step for sealing, and after moving a certain distance, the liquid leaks at the narrow part of the rod, and the resistance is reduced due to the liquid leakage. The shape of the orifice is set such that the groove-shaped orifice is caught by the resistance of the groove formed by the gap between the cylinder and the piston. The object of the present invention is to provide an extremely low-cost shock absorber by significantly reducing the machining accuracy.

That is, the piston rod, which is an important part of a shock absorber, generally adopts a structure in which it is sealed from the cylinder with a sealing member in order to enhance the shock absorbing effect. For this reason, the outer periphery of the piston rod requires ultra-precision machining, and the manufacturing cost of the piston rod is therefore high, making it impossible to provide a shock absorber at a low price.

Therefore, as mentioned above, if the piston rod is completely sealed in relation to the sealing member only during the initial state of buffering, and after the start of buffering, liquid is allowed to leak from around the piston rod, the piston rod can be precision-machined only at the large-diameter step for sealing. The above-mentioned drawbacks have been solved by focusing on the fact that the processing cost can be extremely reduced.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

1 is a cylinder, 2 is a piston disposed within the cylinder 1, 3 is a piston rod protruding from the piston 2, 4 is a seal member, and 5 is a seal in which the diameter of a part of the piston rod 3 is enlarged and the surface is finished. This large-diameter stepped portion is composed of a flat surface portion 5a having a length a and an inclined surface portion 5b having a length b continuous to the flat surface portion 5a so as to be sealed by the seal member 4 only at the maximum extension of the piston stroke. Therefore, when the piston rod 3 strokes in the contraction direction by the length a, the flat surface portion 5a passes the seal member 4, and the inclined surface portion 5b begins to correspond to the seal member 4, there is a play between the piston rod 3 and the seal member 4. formed,
Liquid leaks from this gap.

6 is a constant diameter orifice formed on the low pressure side of the cylinder 1, and 7 is a groove-shaped orifice, which has a groove 7a on the inner wall of the cylinder 1 whose cross-sectional area becomes smaller continuously in the direction of contraction from the maximum extension of the piston stroke, and the piston 2. The liquid that passes through the orifice 7 and moves to the low pressure side as the piston 2 moves passes through the constant diameter orifice 6 and is discharged out of the cylinder 1. At the same time, liquid also leaks from around the piston rod 3.

The constant diameter orifice 6 and the grooved orifice 7 are generally set so that the sum of the resistances of both orifices 6 and 7 is always constant. For this reason, if the piston rod 3 is provided with a large-diameter stepped portion 5 for sealing, and liquid leaks from around the rod 3 during the stroke, the effect of the resistance will affect the sum of the resistances of the two orifices 6 and 7. .

That is, as shown in FIG. 4, if the shape of the groove-shaped orifice 7' is set so that the cross-sectional area simply becomes smaller continuously according to the piston stroke without considering leakage from around the rod 3, the fifth As shown in the figure, the sum of the resistance forces, which is the sum of the resistance A of the groove-shaped orifice 7', the resistance B of the fixed-diameter orifice 6, and the decrease in resistance due to liquid leakage C, is approximately constant between the flat surfaces 5a; It decreases to a minimum at stroke length a+b, and then increases sequentially. Therefore, the sum of the resistance forces is not constant and the buffering effect is reduced.

Therefore, as shown in FIG. 1, the shape of the groove 7a forming the groove-shaped orifice 7 is the same as that shown in FIG. The section b' is set so that the cross-sectional area becomes smaller sharply than the groove 7'a in Fig. 4 from the section a' corresponding to the stroke length a, and the section after the section b' becomes more gradual than the section b'. The area is set to be small, and as shown in Fig. 3, the sum of the low hole (E) of the groove-shaped orifice 7, the resistance (B) of the constant diameter orifice 6, and the decrease in resistance force due to liquid leakage (C) becomes approximately constant. It is designed to provide good buffering performance.

8 is an air supply port used for returning the piston, 9
is the low pressure chamber supply port.

FIG. 6 shows another embodiment of the present invention, in which a relief valve 10 is employed as a constant diameter orifice, and FIGS. 7 to 9 show still other embodiments of the present invention. Then, as shown in FIG. 8, a notch 11 of width W x height U is formed on the outer periphery 2a of the piston 2.
On the other hand, as shown in Figs. 7 and 9, the height t of the protrusion 12 of width W' x height t, which is fitted into the notch 11 in the inner wall of the cylinder 1, is reduced from the maximum extension of the piston stroke. A groove-shaped orifice 13 is formed in the gap between the notch 11 and the protrusion 12, which changes depending on the stroke position. However, the groove-shaped orifice 13 formed in the gap between the notch 11 and the protrusion 12 is configured so that its cross-sectional area becomes smaller in the contraction direction than at the maximum extension of the piston stroke, and both of the above embodiments The same effects can be achieved.

As described above, the present invention forms a large-diameter stepped portion for sealing on the piston rod, so only a portion of the piston rod needs to be precision-machined, and the plating portion can be omitted except for the large-diameter stepped portion, resulting in significantly lower shock absorption. In addition, since the shape of the groove-shaped orifice compensates for the drop in resistance due to liquid leakage from around the piston rod, it is possible to provide good damping performance.

Therefore, if cheap water is used as the liquid and the water fountain from a fixed-diameter orifice or the water leaking from around the piston rod is disposed of outside, the system can operate like a shock absorber for a car stopper on a railway vehicle, etc. Ideal for infrequent applications.

[Brief explanation of the drawing]

1 to 3 show one embodiment of the present invention, in which FIG. 1 is a sectional front view of a compression type single cylinder shock absorber, FIG. 2 is a sectional view of the cylinder in FIG. The figure is an explanatory diagram showing the relationship between piston stroke and resistance force, Figure 4 is a cross-sectional front view of the shock absorber when the shape of the grooved orifice is set without considering liquid leakage from around the piston rod, and Figure 5 is an explanatory diagram showing the relationship between the piston stroke and the resistance force in the case of FIG. 4, FIG. 6 is a sectional front view showing another embodiment of the present invention, and FIGS. 7 to 9 show still another embodiment. Figure 7 is a cross-sectional front view of a compression type single cylinder shock absorber, Figure 8 is a front view of a piston,
FIG. 9 is a sectional view of the cylinder at - in FIG. 7. 1... Cylinder, 2... Piston, 2a... Outer periphery, 3... Piston rod, 4... Seal member,
5...Large diameter stepped portion for sealing, 6...Constant diameter orifice, 7, 13...Groove orifice, 7a...
Groove, 11...notch, 12...projection.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. The sum of the resistance of a groove-shaped orifice whose cross-sectional area decreases continuously according to the piston stroke and the resistance of a constant-diameter orifice through which liquid passes after passing through the groove-shaped orifice. Therefore, in a shock absorber that buffers a piston disposed in a cylinder, the groove-shaped orifice is placed in the gap formed between the cylinder and the piston so that the cross-sectional area becomes continuously smaller in the contraction direction than at the maximum extension of the piston stroke. The relationship between the piston rod and the sealing member is such that the piston rod seals only when the piston stroke is at its maximum extension and leaks at other positions. The shape of the groove-shaped orifice is set so that the decrease in resistance force due to liquid leakage from around the piston rod is added to the resistance of the groove-shaped orifice in advance, and the magnitude of the resistance force acting on the piston with respect to the piston stroke is determined. A compression type single cylinder shock absorber characterized by constant constant compression. 2. A utility model registration request characterized in that the groove-shaped orifice is formed in the inner wall of the cylinder in a gap between a groove whose cross-sectional area becomes smaller continuously in the direction of contraction from the maximum extension of the piston stroke and the outer periphery of the piston. A compression type single cylinder shock absorber according to item 1. 3 The groove-shaped orifice is formed on the inner wall of the cylinder with a protrusion whose height increases in the direction of contraction and whose cross-sectional area continuously increases from the maximum extension of the piston stroke, and on the outer periphery of the piston to fit the protrusion. A compression type single cylinder shock absorber according to item 1 of the scope of the application for utility model registration, characterized in that the shock absorber is formed in a gap between a notch and a notch in which the shock absorber is mounted.