JPS6234989B2 - - Google Patents

Description

[Detailed description of the invention]

Traditionally, dynamic O-rings, along with their groove configuration,
It was widely used as the simplest sealing mechanism. That is, when a rubber ring with a circular cross section is installed, for example, in a groove formed in the inner wall of the housing that slides on the shaft, the circular cross section of the O-ring is, for example, 15 to 15 mm in the radial direction.
While selecting the depth of the groove so that it collapses by about 20%,
The groove width absorbs the increase in the width in the axial direction caused by the crushing of the circular cross section of the O-ring, and also absorbs thermal expansion.
It was constructed so that there was sufficient space for the O-ring to escape against swelling, etc., and its sealing effect was remarkable and simple. However, the essential flaw in the relationship between the O-ring and its conventional groove is that, due to the groove configuration described above, the O-ring always remains in its groove, whether in use (when pressure is applied) or not. Therefore, no matter how good a rubber material or compound with excellent rebound properties is developed and used, the viscosity of the rubber material Entropy based on elasticity Due to the nature of the elastic body itself, deformation due to set, that is, permanent strain due to collapse cannot be avoided. That is, due to an increase in the difference in environmental temperature and an increase in the frequency of use, it is unavoidable that the long life of the O-ring function will be shortened. This is because there is a problem with the structure of the groove itself, which is constantly crushed and subjected to extra load even when not in use. As described above, the present invention was invented to basically eliminate the defects in the relationship between O-rings and grooves, and to specifically specify the dimensions of the grooves so that the O-rings and grooves can be used easily. That is, the O-ring 1 maintains a light contact state at the center within the groove having two roof-like slopes in the cross-sectional shape shown in FIG.
When pressurized, as shown in FIG. 2, the O-ring 1 is pressed against the sloped groove and provides a complete sealing effect. On the other hand, when not in use, the O-ring 1 is released from compression and returns to its substantially free circular cross section. That is, the O-ring 1 effectively seals only when in use, and does not unnecessarily compress and set when not in use. Therefore, when O-rings made of the same material were applied to the grooves of the present invention and the conventional grooves in a comparative test, a several-fold difference in service life was shown. Test temperature using JISB2401P40 O-ring
The results of a continuous test for 500 hours, with one cycle consisting of 30 minutes at 150°C, followed by 30 minutes at -20°C, are shown in the table below.

[Table] Even in tests conducted under the above conditions with the shaft rougher than normal, conventional grooves failed after only 100 hours, whereas the grooves of the present invention showed no leakage and almost no wear even after 500 hours. It showed good results as it was rarely seen. The groove of the present invention used in the experiment is as shown in FIG. 1, and has the advantage that the groove is simple in design and a standard product can be easily used. Further, the relationship between the dimensions a, b, c, d of the groove and the wire diameter of the O-ring is optimal when it is as follows, and serves as a guideline for groove design.
(Figure 1 shows the wire diameter = 3.5.) a=0.7, b=, C=1.7, d=c/2

[Brief explanation of the drawing]

FIG. 1 is a half longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is a half longitudinal sectional view showing the state of the invention during operation.

Claims (1)

[Claims] 1 When the moving O-ring is at rest, it is positioned approximately in the center of the groove and held in a free state where it is not subjected to much compression, while the shaft or housing slides and receives pressure from either one of the axial directions. In this case, the O-ring is placed in two grooves so that the position of the O-ring is shifted from the center of the groove and is crushed at either end, and the cross-sectional shape is shallow at both ends and deep at the center. A pentagonal roof-shaped groove with a slope is formed, and the width of the groove is approximately equal to the wire diameter of the O-ring that accommodates the groove.
1.7 times, and the depth of the groove at both ends is approximately 0.7 of the wire diameter.
A roof-shaped groove for an O-ring characterized by having the same diameter as the wire at the center.