Pipe joints or couplings – Nonmetal to metal – Internal member
Reexamination Certificate
1999-07-15
2001-10-30
Luu, Teri Pham (Department: 3627)
Pipe joints or couplings
Nonmetal to metal
Internal member
C285S133110
Reexamination Certificate
active
06308992
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hose connecting assembly, where a hose connecting tube is pressed into a hose to ensure connection with the hose.
2. Description of the Related Art
There are known hose connecting assemblies, such as those disclosed in JAPANESE PATENT LAID-OPEN GAZETTE No. 9-159077.
FIG. 26
is a partly broken front view illustrating a prior art hose connecting assembly including a branched pipe
100
. Referring to
FIG. 26
, the hose connecting assembly includes the branched pipe
100
having three branched portions
101
,
102
, and
103
, and hoses
111
,
112
, and
113
, into which the branched portions
101
,
102
, and
103
are respectively pressed. A pair of ring-shaped projections
104
and
105
are formed around the circumferential face of each of the branched portions
101
,
102
, and
103
. The ring-shaped projections
104
and
105
have a triangular cross section and are arranged at a certain interval.
FIG. 27
is an enlarged cross sectional view illustrating the branched portion
101
. As shown in
FIG. 27
, the ring-shaped projections
104
and
105
respectively have truncated cone faces
104
a
and
105
a
, which have outer diameters tapered toward the free end of the branched portion
101
, and acute-angled faces
104
b
and
105
b
, which extend between outer edges of the truncated cone faces
104
a
and
105
a
and the base circumference of the branched portion
101
, and which have an acute angle with the truncated cone faces
104
a
and
105
a
, respectively. The hose
111
includes an inner layer
111
a
made of an EPDM rubber, a thread-reinforced layer
111
b
made of braided or spirally networked reinforcing threads, and an outer layer
111
c
made of an EPDM rubber.
In the prior art hose connecting assembly, when the branched portion
101
is pressed into the hose
111
, the ring-shaper projections
104
and
105
apply the force that expands the inner diameter of the hose
111
. This force causes a large reaction force of the thread-reinforced layer
111
b
to limit the expansion. The hose
111
thus securely clamps the branched portion
101
. Since the hose
111
is secured to the branched portion
101
with a large force, this arrangement ensures the secure connection of the hose
111
with the branched portion
101
without using any clamps and by simply pressing the branched portion
101
into the hose
111
.
In the prior art hose connecting assembly, since the hose
111
is joined with the branched portion
101
, without using any clamping fixtures such as clamps, and by simply pressing the branched portion
101
into the hose
111
, a tight seal as well as the large securing force is required. The hose connecting assembly is required to ensure the tight seal even at places where the hose
111
is vibrated against the branched portion
101
, for example, in an engine room of an automobile, and at places where a rotating force is applied to the hose
111
.
SUMMARY OF THE INVENTION
The object of the present invention is thus to provide a hose connecting assembly that enables easy connection with a hose and ensures a tight seal even at a place exposed to vibrations.
At least part of the above and the other related objects is realized by a first hose connecting assembly, where a hose connecting tube is pressed into a hose to ensure connection with the hose. The hose connecting tube includes: a ring-shaped projection formed around an outer circumferential surface of the hose connecting tube to have an outer diameter D1, which is greater than an inner diameter d1 of the hose to which no pressure is applied; and a hollow cylindrical end formed between the ring-shaped projection and a free end of the hose connecting tube to be in close contact with an inner wall surface of the hose and have an outer diameter D2, which is smaller than the outer diameter D1. The hollow cylindrical end has a length of at least about 3 mm along an axis of the hose connecting tube.
In the first hose connecting assembly, the hose connecting tube has the ring-shaped projection, and the hose climbs over the ring-shaped projection when the hose connecting tube is pressed into the hose. The outer diameter D1 of the ring-shaped projection is set to be greater than the inner diameter di of the hose. When the hose connecting tube is inserted into the hose, the ring-shaped projection thus partly expands the inner wall surface of the hose. The hose is designed to have an inner diameter change rate Dc, which is defined by Equation (1) given below, less than or equal to 23% and cause a large reaction force against the diameter-expanding force, where d1 denotes an inner diameter of the hose when no pressure is applied and d2 denotes an inner diameter of the hose when an inner pressure of 0.49 MPa (5 kg/cm
2
) is applied to the hose.
Dc=(d2−d1)×100/d1 (1)
The ring-shaped projection is designed to have a diameter expansion rate T, which is defined by Equation (2) given below, of at least 25%. The diameter expansion rate T here represents a rate of expansion of the hose having the inner diameter d1 to the outer diameter D1 of the ring-shaped projection.
T=(D1−d1)×100/d1 (2)
In the first hose connecting assembly, the hose has a large force to limit the expansion under application of a fluid pressure. When the hose climbs over the ring-shaped projection of the hose connecting tube and expands its diameter, the hose generates a large clamping force against the hose connecting tube as the reaction force. The hose having such a large clamping force does not readily come off the hose connecting tube and ensures a sufficiently tight seal. The hose is thus securely joined with the hose connecting tube without using any specific clamping mechanism, such as clips.
The hose connecting tube has a hollow cylindrical end formed between a free end of the hose connecting tube and the ring-shaped projection. The hollow cylindrical end is in close contact with the hose before the diameter of the hose is expanded by the ring-shaped projection. The hose is thus continuously in close contact with the hollow cylindrical end between the free end of the hose connecting tube and the ring-shaped projection, which expands the diameter of the hose. The hollow cylindrical end causes the hose to be in close contact with its smooth surface between the free end of the hose connecting tube and the ring-shaped projection even when the hose is exposed to vibrations. The hose accordingly keeps the tight seal against the hose connecting tube even under the low-temperature condition and the repeated application of vibrations to the hose.
It is preferable that the hollow cylindrical end has a length of 3 to 7 mm in the axial direction. A length of less than about 3 mm does not ensure a sufficient improvement in sealing property of the seal under the vibration-applying conditions. A length greater than about 7 mm, on the other hand, undesirably increases a frictional force when the hose connecting tube is inserted into the hose, and results in the poor insertion workability. It is accordingly preferable that the hollow cylindrical end has the length in the above range.
In order to make the inner diameter change rate Dc of the hose less than or equal to 23%, the hose may have a thread-reinforced layer embedded in a tubular layer of a rubber material. The thread-reinforced layer may be made of braided reinforcing threads, spirally wounded reinforcing threads, knitted reinforcing threads, or cloth.
It is preferable that at least an outer surface layer of the hose is made of an EPDM rubber. The EPDM rubber has an excellent resistance against ozone and does not crack even with long-term use in the diameter-expanding state.
The ring-shaped projection may have any shape that expands the diameter of the hose and enhances the seal. In accordance with one preferable embodiment, the ring-shaped projection has a truncated cone face and an acute-angled face. The truncated cone face has an outer diameter ta
Ito Koji
Mitsui Kenichi
Nakashima Naomi
Watanabe Norio
Luu Teri Pham
Pillsbury & Winthrop LLP
Toyoda Gosei Co,., Ltd.
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