JP7846890B2 - Pipe fittings - Google Patents

Description

This invention relates to a pipe joint for connecting pipes.

The connections between pipes through which fluids flow are made using brazing, welding, mechanical joints, etc. Brazing and welding require considerable time and skill, and also involve the use of open flames, posing a fire hazard. Therefore, there is a growing demand for mechanical joints, which do not require the use of open flames and are easy to connect.

Patent Document 1 below describes a pipe fitting having a mechanical connection structure. This pipe fitting comprises a tubular intermediate fitting body (fitting body) into which a steel pipe is inserted through an opening at one end, and a connecting nut (nut) that is fitted around the steel pipe and screwed onto one end of the intermediate fitting body. The connecting nut, fitted around the steel pipe behind the projection, is connected to the intermediate fitting body into which the steel pipe, having a projection (bulge) near its tip, is locked to the connecting nut, thereby preventing the steel pipe from coming loose.

The main body of the connecting joint has a male thread formed on the outer surface of one end. Inside the connecting nut, there is a small-diameter hole through which the projection of the steel pipe cannot be inserted, and a larger-diameter hole adjacent to the connecting joint body, through which the projection can be inserted. This larger-diameter hole has a female thread that can be screwed onto the male thread of the connecting joint body. A stepped surface is formed between the large-diameter hole and the small-diameter hole. When the connecting nut is screwed onto the connecting joint body, a space for accommodating the steel pipe projection is formed between the stepped surface and one end of the connecting joint body in the larger-diameter hole.

Japanese Patent Publication No. 2002-257272 (0010, Figure 6)

In the pipe fitting described in Patent Document 1, the spacing of the projection's accommodating space can be adjusted by screwing in and unscrewing the connecting nut, but it was not possible to confirm that the predetermined spacing was maintained. Therefore, the projection on the steel pipe could be damaged by overtightening the connecting nut, or the steel pipe could be connected with insufficient screwing. As a result, the steel pipe could loosen, causing fluid leakage from within the pipe fitting.

Furthermore, when the steel pipe is tightly clamped between the connecting nut and the intermediate joint body, it becomes impossible to rotate the steel pipe in the circumferential direction, making it impossible to change the orientation of a curved steel pipe.
Furthermore, if water was generated within the containment space due to condensation or other reasons, the water would remain inside the space, and repeated freezing and expansion could cause damage to the pipe joints.

The present invention has been made to solve at least one of the above problems, and a pipe joint according to one aspect of the present invention comprises a joint body which is tubular in shape and into which a pipe is inserted through an opening at one end, and a nut which is fitted around the pipe and connected to one end of the joint body by screwing.
A nut, which is fitted around the pipe behind the bulge, is connected to the fitting body into which the pipe, which has a bulge near its tip, is inserted. The bulge of the pipe is locked into the nut, thereby connecting the pipe in a way that prevents it from coming loose.
The above-mentioned joint body has a male thread formed on the outer surface of one end.
Inside the nut, there is a small-diameter hole through which the bulging portion of the pipe cannot be inserted, and a large-diameter hole adjacent to the joint body side, through which the bulging portion can be inserted. The large-diameter hole has a female thread that can be screwed onto the male thread of the joint body, and a stepped surface is formed between the large-diameter hole and the small-diameter hole.
When the nut is screwed onto the joint body, a space for accommodating the bulging portion of the pipe is formed in the large-diameter hole between the stepped surface and one end of the joint body.
The above-mentioned joint body is provided with abutment portion that the nut abuts against when the above-mentioned housing space becomes a predetermined distance when the nut is screwed in.

According to the above configuration, when the nut screwed into the fitting body is brought into contact with the abutment, a predetermined spacing of accommodating space is formed. Therefore, damage to the pipe's bulge due to overtightening of the nut, and loose connection due to insufficient tightening, can be prevented. Consequently, fluid leakage from within the pipe fitting caused by damage to the bulge or loose pipe connection can be prevented.

Preferably, the spacing of the accommodation spaces is set so that the bulging portion of the pipe can move in the circumferential direction within the accommodation space.
With the above configuration, the pipe can be rotated in the circumferential direction, so if the pipe has a curved shape, its orientation can be freely changed.

Preferably, a through hole is formed in the peripheral wall of the nut to connect the housing space with the outside.
According to the above configuration, water generated in the containment space due to condensation, etc., can be discharged. Therefore, it is possible to prevent damage to the pipe joints caused by repeated freezing and expansion of water in the containment space.

According to the present invention, it is possible to provide a pipe fitting that prevents leakage of the fluid flowing inside.

This is an exploded perspective view of a pipe fitting according to one embodiment of the present invention. (A) This is a cross-sectional view of the main parts of the pipe fitting, shown disassembled into the nut and the fitting body. (B) This is a cross-sectional view of the main parts of the pipe fitting. This is a cross-sectional view of the main part showing the process of connecting the pipe fitting to the pipe, where (A) shows the state in which a nut is fitted around the pipe behind the bulging portion of the pipe, (B) shows the state in which the end of the pipe is inserted into the fitting body, and (C) shows the state in which the connection is completed.

The following describes a pipe fitting comprising one embodiment of the present invention with reference to Figures 1 to 3. This embodiment applies the present invention to a pipe fitting for connecting refrigerant pipes that connect the indoor and outdoor units of an air conditioning system.

As shown in Figure 1, the pipe fitting 1 to which the refrigerant pipe P (pipe) is connected has a fitting body 10 and a nut 20.
The refrigerant pipe P is made of metal (in this embodiment, an aluminum alloy) and has a curved shape. The refrigerant pipe P may also be a straight pipe. The refrigerant pipe P has a bulge Pa near the end on the side connected to the pipe joint 1, which is formed by beading and protrudes radially outward. As shown in Figure 2(A), the cross-sectional shape of the outer surface of the bulge Pa is arc-shaped.

The joint body 10 is made of metal, specifically the same aluminum alloy as the refrigerant pipe P in this embodiment, and is formed in a three-pronged tubular shape. The joint body 10 has a main pipe section 11 and a branch pipe section 12 that branches off from the main pipe section 11. A passage hole 10a connects the interiors of the main pipe section 11 and the branch pipe section 12.

An opening 12a is formed at the tip of the branch pipe section 12 into which the refrigerant pipe P is inserted. The inner diameter of the opening 12a is smaller than the outer diameter of the bulge Pa of the refrigerant pipe P. When the tip of the refrigerant pipe P is inserted into the opening 12a, the bulge Pa comes into contact with the tip surface of the branch pipe section 12.

A male thread 12b for screwing a nut 20 is formed on the outer circumferential surface of the tip of the branch pipe section 12. A stopper portion 13 is provided on the inner outer circumferential surface of the male thread 12b, against which the tip of the screwed nut 20 abuts. The stopper portion 13 protrudes radially outward from the branch pipe section 12, extends in an annular shape, and has a contact surface 13a facing the nut 20.

An annular seal material mounting groove 12c is formed on the inner circumferential surface of the passage hole 10a beyond the opening 12a. An O-ring 30, which is a sealing member, is fitted into the seal material mounting groove 12c.

The O-ring 30 is formed in an annular shape from an elastic material such as rubber, has a circular cross-section, and is elastically expandable and contractible. The outer diameter of the O-ring 30 is slightly larger than the inner diameter of the seal material mounting groove 12c, and the inner diameter of the O-ring 30 is slightly smaller than the outer diameter of the refrigerant pipe P. The O-ring 30 presses against the outer surface of the refrigerant pipe P inserted into the passage hole 10a through the opening 12a, sealing the space between the outer surface of the refrigerant pipe P and the inner surface of the passage hole 10a. In this sealed state, the refrigerant pipe P can be rotated in its circumferential direction.

The nut 20 is made of aluminum alloy and is screwed onto the tip of the branch pipe section 12. Inside the nut 20, there is a small-diameter hole 21 through which the bulge Pa of the refrigerant pipe P cannot be inserted, and a large-diameter hole 22 adjacent to the small-diameter hole 21 on the branch pipe section 12 side, through which the bulge Pa can be inserted.

The large-diameter hole 22 has a female thread 22a that can be screwed onto the male thread 12b of the branch pipe section 12. Between the large-diameter hole 22 and the small-diameter hole 21, a stepped surface 23 is formed, facing the axial direction of the nut 20. A through hole 24 is formed in the peripheral wall of the nut 20 on the branch pipe section 12 side of the stepped surface 23, allowing communication between the inside and outside.

On the outer surface of the nut 20 opposite to the branch pipe section 12, a tool-holding section 25 is formed for attaching tools such as wrenches. The tool-holding section 25 is formed by a pair of parallel flat surfaces.

As shown in Figure 2(B), when the nut 20 is screwed onto the branch pipe section 12, a accommodating space 26 for housing the bulging portion Pa of the refrigerant pipe P is formed in the large-diameter hole 22 between the stepped surface 23 and the tip of the branch pipe section 12. When the nut 20 is screwed in, the accommodating space 26 reaches a predetermined distance suitable for housing the bulging portion Pa, and the nut 20 comes into contact with the contact surface 13a of the abutment portion 13 of the branch pipe section 12.

In this configuration, the through-hole 24 connects the containment space 26 to the outside. This allows for the discharge of water even if condensation occurs within the containment space 26 during the connection of the refrigerant pipe P. Therefore, damage to the pipe joint 1 due to repeated freezing and expansion of water accumulated within the containment space 26 can be prevented.

The process of connecting the refrigerant pipe P to the pipe joint 1 with the above configuration will be explained with reference to Figure 3.
As shown in Figure 3(A), the end of the refrigerant pipe P is connected to the pipe joint 1, and a nut 20 is fitted around the refrigerant pipe P behind the bulging portion Pa.
Next, as shown in Figure 3(B), the refrigerant pipe P is inserted into the passage hole 10a through the opening 12a and passed through the O-ring 30, so that the bulging portion Pa abuts against the tip surface of the branch pipe portion 12. Subsequently, the nut 20 is screwed onto the branch pipe portion 12 to form a housing space 26, and the bulging portion Pa is housed between the stepped surface 23 and the tip of the branch pipe portion 12.

As shown in Figure 3(C), the nut 20 is screwed in and brought into contact with the contact surface 13a of the abutment portion 13. At this time, the bulge portion Pa is housed within a housing space 26 with an appropriate spacing to prevent damage to the bulge portion Pa or loose connection of the refrigerant pipe P. In this embodiment, within the housing space 26, the bulge portion Pa contacts the stepped surface 23 and the tip of the branch pipe portion 12, slightly compressing it in the axial direction of the refrigerant pipe P, preventing movement in the circumferential direction of the refrigerant pipe P. The bulge portion Pa is locked to the nut 20, thereby connecting the refrigerant pipe P to the pipe joint 1 in a secure, non-loosening state.

According to the above embodiment, when the nut 20 screwed into the branch pipe section 12 abuts against the abutment section 13, a accommodating space 26 with a predetermined spacing suitable for accommodating the bulge section Pa is formed. Therefore, damage to the bulge section Pa due to overtightening of the nut 20, and connection of the refrigerant pipe P in a loose state due to insufficient tightening, can be prevented. Consequently, leakage of refrigerant from the pipe joint 1 caused by damage to the bulge section Pa or a loose connection of the refrigerant pipe P can be prevented.

It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention.
The spacing of the accommodation spaces 26 may be such that the bulging portion Pa does not collapse against the stepped surface 23 and the tip of the branch pipe portion 12.
The spacing of the accommodation spaces 26 may be such that the bulging portion Pa that abuts the stepped surface 23 and the tip of the branch pipe portion 12 can move in the circumferential direction of the refrigerant pipe P. This allows the refrigerant pipe P to be rotated circumferentially with respect to the pipe joint 1, and if the refrigerant pipe P has a curved shape, its orientation can be freely changed.
In the above embodiment, the refrigerant pipe P was connected to the end of the branch pipe section 12, but it may also be connected to the end of the main pipe section 11.
In the above embodiment, the shape of the pipe joint was a three-pronged shape with one branch, but it may also be a shape without branches, or a cross-shaped pipe with two branches.
The pipe connected to the pipe fitting is not limited to a refrigerant pipe; it may also be a pipe through which other fluids flow.
The metals used in pipe fittings and pipes are not limited to aluminum alloys; they may also be copper, brass, stainless steel, iron, or other materials.

This invention can be applied to pipe fittings for connecting pipes.

P Refrigerant pipe
Pa Bulging section 1 Pipe fitting 10 Fitting body 10a Passage hole 11 Main pipe section 12 Branch pipe section 12a Opening 12b Male thread 12c Seal material mounting groove 13 Butt section 13a Contact surface 20 Nut 21 Small diameter hole section 22 Large diameter hole section 23 Stepped surface 24 Through hole 25 Tool hook section 26 Storage space 30 O-ring

Claims (3)

A pipe joint comprising a tubular joint body into which a pipe is inserted through an opening at one end, and a nut fitted around the pipe and screwed onto one end of the joint body, wherein a pipe having a bulge near its tip is inserted into the joint body, and the nut fitted around the pipe behind the bulge is connected, and the bulge of the pipe is locked to the nut, thereby connecting the pipe in a way that prevents it from coming loose,
The above-mentioned joint body has a male thread formed on the outer surface of one end thereof.
Inside the nut, there is a small-diameter hole through which the bulging portion of the pipe cannot be inserted, and a large-diameter hole adjacent to the joint body side that allows the bulging portion to be inserted. The large-diameter hole has a female thread that can be screwed onto the male thread of the joint body, and a stepped surface is formed between the large-diameter hole and the small-diameter hole.
When the above nut is screwed onto the above joint body, a accommodating space for the bulging portion of the pipe is formed in the large-diameter hole between the stepped surface and one end of the above joint body.
The above-mentioned joint body is provided with a stopper portion that the nut abuts against when the above-mentioned housing space becomes a predetermined distance when the nut is screwed in .
The above-mentioned pipe is made of metal and has a curved shape. The bulging portion of the pipe is bent so that the peripheral wall of the pipe protrudes radially outward. On the inner surface of the pipe inside the bulging portion, grooves spaced apart in the axial direction are formed in an annular shape extending in the circumferential direction.
A pipe joint characterized in that the spacing of the above-mentioned accommodation spaces is such that the stepped surface and the tip of the joint body can abut and move in the circumferential direction to the extent that the bulging portion does not collapse . A pipe fitting according to claim 1,
A passage hole is formed inside the main body of the joint, and this passage hole has a first passage hole portion connected to the opening into which the pipe is inserted, and a second passage hole portion located further inside than the first passage hole portion.
The first passage hole has an annular mounting groove formed on its inner circumferential surface, into which an annular sealing member is fitted. When the space between the inner circumferential surface and the outer circumferential surface of the pipe is sealed by the sealing member, the pipe is rotatable in the circumferential direction.
A pipe fitting characterized in that the inner diameter of the second passage hole is formed to be smaller than the outer diameter of the pipe. A pipe fitting according to claim 1 or 2,
A pipe fitting characterized in that a through hole is formed in the peripheral wall of the nut, which connects the housing space with the outside.