Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal for other than internal combustion engine – or...
Reexamination Certificate
1999-04-22
2001-04-03
Melius, Terry Lee (Department: 3628)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal for other than internal combustion engine, or...
C277S636000
Reexamination Certificate
active
06209885
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
This invention relates to boots for universal joints used in order to cover and protect an operation portion of the universal joints. More particularly, this invention relates to boots for universal joints having an excellent durability and also having an excellent impact strength. Still more particularly, this invention relates to boots for universal joints made of thermoplastic elastomer.
2. Related Art
Heretofore, it is well known, as shown in
FIG. 8
, that a boot for a universal joint made of resin is designed to have an annular fitting portion
52
on the side of a relatively large diameter in the axial direction (hereinafter it is called large-diameter side) of a bellows portion
51
and also to have another annular fitting portion
53
on the side of a relatively small diameter in the axial direction (hereinafter it is called small-diameter side) of the bellows portion
51
. The fitting portion
52
of the large-diameter side is fixed on a periphery of an outer ring portion
54
of the universal joint, and the fitting portion
53
of the small-diameter side is fixed on an outer periphery of a shaft
55
as shown in
FIG. 8
, thereby to cover and protect the operation portion of the universal joint. There is an opening portion
60
in the radially inner side of the outer ring portion
54
. Bellows usually have several mountainous and ravine shape portions, namely crest
58
and trough
57
portions. Moreover, a frustoconical shape enlarged portion
56
having an approximately frustoconical shape in cross section is provided in the vicinity of the large-diameter-side portion, in order to lower a contact pressure between each adjacent mountainous or slanting portion
59
shape portion at the time when the bellows is bent in a sharp angle, and to also relieve bellows portion
51
from contact with the shaft
55
or the opening portion
60
as well. The enlarged portion
56
is placed between the bellows portion
51
and the fitting portion
52
of the larger-diameter side (Japanese Registered Patent 2525619).
As shown in
FIG. 9
, the inclination angle between the slanting portions
59
of the bellows extending from the trough portions to the small-diameter side and the axial direction of the boots, is smaller than that of the angle between the enlarged portion
4
exdending from large-diameter side to small-diameter side and the axial direction of the boots. When the boot is bent, the force “f” in the direction of the arrow is added, and the enlarged (frustoconical) portion
56
is forced to move toward the arrow direction “d”, to prevent the bellows portion
51
from interfering with the opening portion
60
.
Since such kind of boots made of resin are excellent in durability, functionality and recycling ability, when compared to conventional boots made of rubber, so that the resin boots have become widely used in recent years. However, due to the higher stiffness of the resin boots compared to the boots made of rubber, the following inconveniences have resulted.
That is to say, a fitting member is used when the fitting portion
52
of the large-diameter side of the boot made of resin is fixed on the outer ring portion
54
of the universal joint. A clamp is generally used as the fitting member. In this case, the clamp having higher stiffness than that of a conventional clamp for rubber boots has been used, because of the higher stiffness of the resin boots. Caulking type clamps having higher stiffness are usually used for resin boots.
The caulking type clamp is usually provided with a tightly-clamping portion (not shown) in a specific area of its circumference, and the tightly-clamping portion protrudes relatively largely from the outer peripheral surface of the band portion of the clamp, toward the radially outwardly direction.
Therefore, as shown in
FIG. 8
, crest portion
58
or slanting portion
59
of the first mountainous portion or annular enlarged portion
56
on the large-diameter side of the bellows
51
is prone to bend toward the clamping side and interfere with the tightly-clamping portion or boot's band, when the boot is bent sharply. With this repeating interference, the annular enlarged portion
56
and the bellows portion
51
are prone to be damaged.
There is also a shortage in physical strength against impact in the vicinity of the enlarged portion. When impact is added from outside of the boot in the vicinity of the enlarged portion as shown by the arrow “g” or “g′” in FIG.
9
. The portion around the enlarged portion or the slanting portion
59
in
FIG. 9
is impinged to the outer ring portion
54
, to often cause damage in the boot.
In view of the above-mentioned problems, an object of the present invention is to provide bellows type boots for the universal joint, which does not interfere with a tightly-clamping portion of a boot clamping means, having an excellent durability, and also having an excellent impact strength.
SUMMARY OF THE INVENTION
In order to achieve the above-described object, the boots for universal joints of the present invention comprise a bellows having a larger-diameter portion at an axially end portion thereof, a smaller-diameter portion at another axially end portion thereof, a bellows portion placed between said larger-diameter portion and said smaller-diameter portion, an annular fitting (clamped) portion, which is mounted and fitted on the outer periphery of the universal joints by a clamp means, an annular relief portion placed between said bellows portion and said clamped portion, and an annular spacer portion having a specific length between said clamped portion and said annular relief portion. The annular relief portion is preferably directly and consecutively connected to the slanting portion of the trough portion in the bellows. The annular relief portion has preferably an arcuate in cross section having a predetermined curvature.
The object of the present invention can be also achieved by the following construction. The boot according to the present invention comprises a bellows, an annular fitting portion, an annular relief portion and an annular spacer portion. Said spacer portion comprises an annular or tubler shape thrust portion having a side wall on its larger-diameter side, said side wall being higher than the thickness of a clamping band, an annular rising-up portion molded consecutively with said annular or tubular thrust portion in one body and placed in a substantially axial direction of said thrust portion from an outer peripheral portion of said thrust portion, and an enlarged portion molded consecutively with said rising portion in one body and placed in an obliquely outer direction or a radially outer direction from an axially large-diameter-side end portion of said rising-up portion.
Especially, the angle between the direction of said enlarged portion and the radial direction of said boot, is preferably smaller than the angle between the direction of the slanting portion of the bellows extending from said trough to the smaller-diameter-side and a radially outwardly direction of said boots.
Furthermore, a larger-diameter-side outer peripheral corner in the radially outwardly portion of said thrust portion is preferably chamfered.
The boots according to the invention provided with the spacer portion having a predetermined length and being placed between the fitting portion and the relief portion so that the relief portion can be placed more apart from the clamping portion by the length of this spacer portion.
Therefore, even when the shaft is bent sharply, the relief portion does not frequently reach to the tightly-clamping portion of the clamp, thereby preventing the relief portion from interfering with the tightly-clamping portion. Moreover, it is more preferable to set the diameter of the spacer portion to a smaller diameter than the diameter of the relief portion, so that the spacer portion can not newly interfere with the tightly-clamping portion in place of the relief portion.
The spacer portion comprises the thrust por
Mukaida Toshihiro
Umeno Selya
Jacobson Price Holman & Stern PLLC
Melius Terry Lee
Miller William L.
NOK Corporation
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