Sealing apparatus

Abstract

The present invention provides a sealing apparatus which can perform excellent sealing performance even when the hardness is reduced. The sealing apparatus which is composed of rubber-like elastomer with a hardness Hs of 90 is characterized in that: when a diameter of a top end (11a) of a first lip (11) which contacts with a groove bottom surface (21) of an annular groove (20) is set to R1, a diameter of a top end (12a) of a second lip (12) which contacts with an outer peripheral surface (30) of a shaft (3) slidably is set to R2, a diameter of the groove bottom surface (21) is set to r1, and a diameter of the outer peripheral surface (30) of shaft is set to r2, a relationship is satisfied, namely [the absolute value of (R1-R2)] / 2 = ([the absolute value of (r1-r2)] / 2)*1.3 (+ / -0.03). When an outside diameter at the groove bottom of a pressed groove (13) is set to R3, and the inner diameter at the groove bottom of the pressed groove (13) is set to R4, a relationship is satisfied, namely 4<=((R3-R4) / [the absolute value of (r1-r2)]-1)*100<=8. An inner peripheral surface (14) of a base part (10) is a conical surface which faces a low pressure side so the base part (10) inclines with a mode that the width of the radial cross section reduces gradually. An inclination angle alpha of the conical surface relatively to the axial direction satisfies a relationship: 3 DEG <=alpha<= 7 DEG.

Description

technical field [0001] The present invention relates to sealing devices used in hydraulic cylinders and the like. Background technique [0002] refer to Figure 8 ~ Figure 10 The prior art sealing device will be described. Figure 8 is a schematic half-sectional view of a prior art sealing device. Figure 9 It is a schematic half-sectional view showing the state of use of the prior art sealing device, wherein (a) shows the state of no pressure, and (b) shows the state of pressurization. Figure 10 It is a graph showing the contact surface pressure distribution of a conventional sealing device, wherein (a) shows the contact surface pressure distribution at low pressure, and (b) shows the contact surface pressure distribution at high pressure. [0003] As a sealing device for the piston rod (rod) of the hydraulic cylinder, such as Figure 8 The lip seal 100 is shown. The lip seal 100 is an annular sealing member, and is used by being installed in an annular groove provided...

AI Technical Summary

Problems solved by technology

However, in the case of the lip seal 100 formed of a low-hardness polyurethane material, the amount of deformation during pressurization is large (see Figure 9 )

In addition, there are cases where the surface pressure gradient on the lip side becomes gentle and the sealing performance deteriorates (see Figure 10 )

[0009] Moreover, if the material is made of a low hardness material, the pressure resistance of the lip seal 100 is also likely to decrease.

For example, due to the large amount of deformation during pressurization, extrusion into the annular gap occurs, which easily causes damage, etc.

Therefore, the shape of the lip seal 100 has to be designed in consideration of pressure resistance

Images