Patent Description:
A bend-shaped pipe joint referred to as an elbow joint that is made of synthetic resin and includes straight sections on both sides of a bend section is a known example of a pipe joint for connecting water drainage pipes.

A conventional mold for molding such a bend-shaped pipe joint generally includes an upper mold and a lower mold for molding outer contours of the pipe j oint, a first slider pin for forming a flow path on one side of the pipe joint as demarcated by a bend-shaped central section, and a second slider pin for forming a flow path on the other side thereof.

The first slider pin and the second slider pin are provided to the mold so as to be capable of sliding along an axial direction. Thus, the flow path inside the bend section needs to be formed without reverse taper such that the first slider pin and the second slider pin can be extracted from the pipe joint after molding.

Namely, a radial direction distance of both the first slider pin and the second slider pin from a central axis to an outer peripheral face needs to be either uniform along the axial direction, or to decrease on progression toward a pin leading end side (in other words have a tapered shape).

Thus, although a portion of both the first slider pin and the second slider pin forming a wall face at a bend outer side of the bend section may be curved such that the radial direction distance gradually decreases on progression toward the leading end, a portion forming a bend inner side of the bend section has to be formed in a straight line shape so as to enable the slider pin to be extracted from the molded joint.

Thus, in the flow path at a bend section formed using the first slider pin and the second slider pin that slides in a direction orthogonal to the first slider pin configured as described above, although a curved face may be formed at the bend outer side, the straight section of the first slider pin and the straight section of the second slider pin abut each other at the bend inner side so as to form a right-angled corner.

Thus, when a fluid such as water flows along the pipe joint, the flow of water changes direction relatively smoothly along the curved face at the bend outer side. However, the flow changes direction suddenly due to the corner at the bend inner side, causing a vortex that resists the flow and leads to an increased loss in pressure.

<CIT> proposes a pipe joint to reduce pressure loss. Attention is also drawn to the disclosures of <CIT>, <CIT> and <CIT>.

<CIT> discloses two pipe joint manufacturing methods. In the first manufacturing method, a leading end of a straight pin (what is referred to as a slider pin) that can be extracted in a straight line is provided with a curve-shaped movable block that is capable of sliding off the pin body in a circular arc. A pipe joint is molded using a mold in which a flow path at a bend section is molded using a moveable joint, and a flow path at a straight section is molded using the straight pin. However, in this first manufacturing method, the configuration of the pin is complex and so there are a large number of components configuring the mold.

In the second manufacturing method, a tube-shaped insert with a curved shape overall is disposed in a mold, and molten resin is injected into a cavity inside the mold such that the insert and the resin become an integral unit. However, presetting the curved insert in the mold when molding a pipe joint takes a lot of effort. Moreover, in cases in which the tube-shaped insert with a curved shape overall is molded using synthetic resin, a mechanism in which a curved pin is slid along the curve direction is required in a mold to form a curved flow path. The structure of the mold is therefore more complex and requires greater precision than in molds in which a straight pin is made to slide.

Thus, the first manufacturing method and the second manufacturing method both leave room for improvement with respect to manufacture.

In consideration of the above circumstances, an object of the present disclosure is to provide a flow path structure connecting plural flow paths extending in different directions that reduces pressure loss and is simple to manufacture.

A flow path structure according to the present invention is provided as claimed in claim <NUM>.

In the flow path structure according to the present invention, the plural flow paths each extending in a different direction are connected together, such that the flow-path inner corner is formed inside the flow path at the connecting section between the one flow path and the other flow path.

By disposing the adapter adjacent to the flow-path inner corner, the one flow path and the other flow path are coupled together at the curving curved flow path inner wall face, and fluid flows along this curving curved flow path inner wall face. Thus, fluid flows more smoothly and pressure loss is reduced compared to cases in which the flow suddenly changes direction at the flow-path inner corner.

The adapter is molded as a separate component to the members configuring the flow path structure, and can be attached to the members configuring the flow path structure post-production. Thus, unlike in the Background Art, there is no need for an operation to position and preset an insert in the molding processes of the members configuring the flow path structure, thereby enabling the effort required to mold the members configuring the flow path structure to be reduced compared to the Background Art.

Moreover, there is no need to provide the mold for molding the members configuring the flow path structure with a pin having a complex structure provided with a curve-shaped movable block at its leading end as in the Background Art in order to form the corner-less bending flow path. This enables the mold to be formed with a simple structure.

Note that in the present disclosure, the corner is formed at a portion where flow paths extending in different directions are connected to one another, in other words the corner refers to a portion with a pointed shape at its leading end. However, in the present disclosure, the corner may also refer to cases in which the corner is slightly chamfered, for example with a chamfer dimension of no greater than <NUM>% with respect to an internal diameter of the flow path, and to cases in which a rounded corner or the like is formed at the leading end. Advantageous Effects of Invention.

As described above, the flow path structure of the present disclosure exhibits excellent advantageous effects of enabling the flow path structure connecting plural flow paths extending in different directions to be obtained that reduces pressure loss and is simple to manufacture.

Explanation follows regarding a pipe joint <NUM> according to an exemplary embodiment applied with a flow path structure of the present disclosure, with reference to <FIG>. Note that in the present exemplary embodiment, a circular shape refers to a true circle (a dimensional error of for example approximately ±<NUM>% being permitted for the radius), whereas a non-circular shape refers to a shape that is not a true circle, such as an elliptical shape.

As illustrated in <FIG>, as an example, the pipe joint <NUM> of the present exemplary embodiment connects together pipes employed in supplying water or the like, and is what is referred to as an elbow pipe joint formed with an L-shaped profile in side view.

The pipe joint <NUM> is configured including a joint body <NUM>, a cap <NUM>, seal members <NUM>, a spacer <NUM>, a retention ring <NUM>, a lock ring <NUM>, an adapter <NUM>, and so on.

As illustrated in <FIG>, as an example, the joint body <NUM> of the present exemplary embodiment is a molded component made of synthetic resin, and is formed with an L-shaped profile in side view. The joint body <NUM> includes a circular tube-shaped first straight section <NUM> extending in a straight line, a circular tube-shaped second straight section <NUM> extending in a straight line in a direction orthogonal to the first straight section <NUM>, and a tube-shaped bend section <NUM> that connects between the first straight section <NUM> and the second straight section <NUM>.

Since the first straight section <NUM> and the second straight section <NUM> have the same configuration and the same dimensions, explanation only follows regarding the first straight section <NUM>. Note that same reference numerals are allocated to configuration of the second straight section <NUM> that is the same as that of the first straight section <NUM>, and explanation thereof is omitted.

As illustrated in <FIG>, a first housing area <NUM> that has a uniform diameter along its axial direction and a circular shape in cross-section perpendicular to its axial direction is provided inside the first straight section <NUM> at an opening side of the first straight section <NUM> (the opposite side to the bend section <NUM>). A second housing area <NUM> that has a uniform diameter along its axial direction and a circular shape that is slightly smaller in diameter than the first housing area <NUM> in cross-section perpendicular to its axial direction is also provided inside the first straight section <NUM> at a back side of the first housing area <NUM> (the bend section <NUM> side). A first step <NUM> is thereby formed between the first housing area <NUM> and the second housing area <NUM> inside the joint body <NUM>.

A bending flow path <NUM> is provided bending inside the bend section <NUM> so as to follow its axial line in cross-section view. A corner 38A is provided at a bend inner side, and a curved bend-outer-side curved flow-path face 38B is provided at a bend outer side, of the bending flow path <NUM>.

As illustrated in <FIG>, as viewed from the direction of an axial line 26CL of the first straight section <NUM>, the half of an end portion of the bending flow path <NUM> that is on the curved bend-outer-side curved flow-path face 38B side of the axial line 26CL has a shape (a cross-section profile perpendicular to its axis) that is semicircular with a radius r. However, the half of the end portion that is on the opposite side to the curved bend-outer-side curved flow-path face 38B side of the axial line 26CL has a non-semicircular shape (half of a substantially elliptical shape), such that the end portion has a substantially elliptical shape overall.

Note that, in the present exemplary embodiment as an example, the profile of the corner 38A-side half of the bending flow path <NUM> in cross-section perpendicular to its axis gradually approaches a semicircular shape on progression from the end portion toward an axial direction central portion of the bending flow path <NUM>. Thus, as viewed overall, the profile of the bending flow path <NUM> in cross-section perpendicular to its axis gently changes from a substantially elliptical shape to a substantially circular shape on progression from the end portion toward the axial direction central portion.

An internal diameter (opening area) of the end portion of the bending flow path <NUM> is smaller than an internal diameter (opening area) of the second housing area <NUM> of the first straight section <NUM>. Thus, a second step <NUM> is formed between the bending flow path <NUM> and the second housing area <NUM> inside the joint body <NUM>.

As illustrated in <FIG>, <FIG>, and <FIG>, the adapter <NUM> illustrated in <FIG> is configured as a separate body to the joint body <NUM> and is inserted into the second housing area <NUM> of the first straight section <NUM> and the bending flow path <NUM>. In the present exemplary embodiment as an example, the adapter <NUM> is a molded component made of synthetic resin.

As illustrated in <FIG> and <FIG>, the adapter <NUM> includes a circular tube shaped main body <NUM> for insertion into the second housing area <NUM> of the first straight section <NUM>. An external diameter of the main body <NUM> is slightly smaller than an internal diameter of the second housing area <NUM> so as to enable insertion into the second housing area <NUM>. An internal diameter of the main body <NUM> is slightly larger than an internal diameter of a pipe <NUM> (see <FIG>) so as to enable insertion of the pipe <NUM>.

A ring shaped wall <NUM> is integrally formed to one end side of the main body <NUM>. The wall <NUM> is formed with a circular hole <NUM> that has a smaller diameter than the internal diameter of the main body <NUM> and the same diameter as the internal diameter of the pipe <NUM>. The circular hole <NUM> is formed coaxially to the main body <NUM>.

A protrusion <NUM> is integrally formed to an outer face (a face on the opposite side to the main body <NUM>) of the wall <NUM>. As illustrated in <FIG>, the protrusion <NUM> is curved as viewed along the axial direction. As illustrated in <FIG>, an inner peripheral face 50A of the protrusion <NUM> is curved in a circular arc shape.

As illustrated in <FIG>, a recess <NUM> into which the protrusion <NUM> is fitted is formed in an inner peripheral face of the bend section <NUM> of the joint body <NUM>. Thus, the attachment orientation, in other words the positioning, of the protrusion <NUM> is set by inserting and fitting the protrusion <NUM> into the recess <NUM>.

In the present exemplary embodiment, by inserting and fitting the protrusion <NUM> into the recess <NUM>, a leading end of the protrusion <NUM> of one adapter <NUM> and a leading end of the protrusion <NUM> of another adapter <NUM> can be made to contact each other.

As illustrated in <FIG>, the inner peripheral face 50A of the protrusion <NUM> is smoothly linked to an inner peripheral face of the circular hole <NUM> in the wall <NUM> without any unevenness. The profile of the inner peripheral face 50A in cross-section perpendicular to its axis is a circular arc shape with a radius of curvature r that is the same as the inner peripheral face of the circular hole <NUM>, in other words a semicircular shape. The circular arc shape of the inner peripheral face 50A with the radius r spans from circular hole <NUM> to the leading end of the protrusion <NUM>.

As illustrated in <FIG>, an adapter <NUM> is also inserted into the second straight section <NUM>. Thus, the leading end of the protrusion <NUM> of one adapter <NUM> inserted into the first straight section <NUM> and the leading end of the protrusion <NUM> of the other adapter <NUM> inserted into the second straight section <NUM> contact one another.

As illustrated in <FIG> and <FIG>, a pair of protrusions <NUM> that extend along the axial direction are formed to an outer peripheral portion of the main body <NUM> of the adapter <NUM>. As illustrated in <FIG> and <FIG>, a pair of grooves <NUM> that extend along an axial line direction are formed in the second housing area <NUM> of the joint body <NUM> where the main body <NUM> is inserted. The protrusions <NUM> of the adapter <NUM> engage (fit together) with the grooves <NUM>.

Note that configuration is preferably such that friction between the protrusions <NUM> and the grooves <NUM> when the protrusions <NUM> are inserted into the grooves <NUM> enables the adapter <NUM> to be retained. For example, friction between the protrusions <NUM> and the grooves <NUM> may be generated by making the width of the protrusions <NUM> slightly larger than the width of the grooves <NUM>, or making the height of the protrusions <NUM> slightly larger than the depth of the grooves <NUM>. This enables the adapter <NUM> to be suppressed from falling out after the adapter <NUM> has been inserted into the joint body <NUM>.

Note that it is also possible to make the diameter of the main body <NUM> slightly larger than the internal diameter of the second housing area <NUM>, enabling the adapter <NUM> to be press-fit into the second housing area <NUM> such that friction between the inner peripheral face of the main body <NUM> and an inner peripheral face of the second housing area <NUM> retains the adapter <NUM> inside the joint body <NUM>.

As illustrated in <FIG>, the seal member <NUM> formed from an elastic material such as rubber as an example, the spacer <NUM> formed from synthetic resin as an example, the seal member <NUM>, and the retention ring <NUM> formed from synthetic resin as an example, are inserted into the first housing area <NUM> of the first straight section <NUM> in sequence from the back side (the second housing area <NUM> side).

One end side of the retention ring <NUM> is disposed inside the first housing area <NUM>. A large diameter portion <NUM> with a larger diameter than the one end side is formed at another end side of the retention ring <NUM>. The large diameter portion <NUM> is disposed outside the end portion of the first straight section <NUM>. A tapered lock ring retaining portion <NUM> that gradually increases in diameter on progression toward the other end side is formed around an inner periphery of the other end side of the retention ring <NUM>.

The cap <NUM> is formed in a circular tube shape, and is fitted onto an outer periphery of the first straight section <NUM>. A step <NUM> is formed inside the cap <NUM>. The large diameter portion <NUM> of the retention ring <NUM> and an outer peripheral portion of the lock ring <NUM> are sandwiched between the step <NUM> and the end portion of the first straight section <NUM>. By fitting the cap <NUM> onto the outer periphery of the first straight section <NUM> in this manner, the adapter <NUM>, the seal members <NUM>, the spacer <NUM>, the lock ring retaining portion <NUM>, and the lock ring <NUM> are prevented from detaching from the first straight section <NUM>.

Plural claws 22Athat catch onto an outer peripheral face of the pipe <NUM> so as to suppress the pipe <NUM> from detaching are formed to an inner peripheral portion of the lock ring <NUM>.

Namely, the pipe joint <NUM> of the present exemplary embodiment is what is referred to as a one-touch joint that suppresses the pipe <NUM> from detaching simply by the pipe <NUM> being inserted therein.

Next, explanation follows regarding the sequence in which the pipe <NUM> is connected to the pipe joint <NUM> of the present exemplary embodiment, as well as operation and advantageous effects.

First, in order to connect the pipe <NUM> to the pipe joint <NUM>, the pipe <NUM> is inserted into the joint body <NUM> through an opening in the cap <NUM>. The pipe <NUM> is inserted until a leading end thereof abuts the wall <NUM> of the adapter <NUM>.

Note that the adapter <NUM> may be either inserted into the joint body <NUM> in advance when the pipe joint <NUM> is assembled at the manufacturing plant, or inserted into the joint body <NUM> when the pipe <NUM> is inserted at a construction site. In the pipe joint <NUM> of the present exemplary embodiment, friction is generated when the protrusions <NUM> provided to the adapter <NUM> are inserted into the grooves <NUM> provided to the joint body <NUM>, such that the adapter <NUM> can be suppressed from detaching without having to use adhesive or the like.

When the pipe <NUM> is inserted into the pipe joint <NUM> in this manner, the claws 22A on the inner peripheral side of the lock ring <NUM> catch onto the outer peripheral face of the pipe <NUM>, such that the pipe <NUM> is suppressed from detaching. The seal members <NUM> disposed between the pipe <NUM> and the first housing area <NUM> make close contact with the outer peripheral face of the pipe <NUM> and an inner peripheral face of the first housing area <NUM>, such that any gaps between the pipe <NUM> and the joint body <NUM> are sealed off by the seal members <NUM>, and water flowing inside the pipe joint is suppressed from leaking out.

In a state in which the leading end of the pipe <NUM> is abutting the wall <NUM> of the adapter <NUM>, the axial line of the pipe <NUM> and the axial line of the circular hole <NUM> formed in the wall <NUM> of the adapter <NUM> are aligned, such that the flow path inside the pipe <NUM> and the circular hole <NUM> are smoothly linked together without any unevenness.

Once both the adapters <NUM> have been attached to the joint body <NUM>, the protrusions <NUM> of the adapters <NUM> are disposed adjacent to the corner 38A of the bending flow path <NUM> so as to cover the corner 38A, such that the inner peripheral faces 50A of the two protrusions <NUM> are linked together to form a curved face at the bend inner side of the bending flow path <NUM> as illustrated in <FIG>. Thus, fluid flowing at the bend inner side of the bending flow path <NUM> changes direction more smoothly than in cases in which the corner 38A is exposed, thereby enabling pressure loss to be reduced.

Furthermore, the bending flow path <NUM> of the bend section <NUM> to which the adapter <NUM> is attached is bordered by the curved bend-outer-side curved flow-path face 38B at the bend outer side thereof and the inner peripheral face 50A of the protrusion <NUM> at the bend inner side thereof so as to have a circular cross-section profile with the same diameter as the flow path of the pipe <NUM>. Thus, the cross-section profile of the flow path does not change mid-flow, thereby enabling pressure loss that would arise due to the cross-section profile of the flow path changing mid-flow to be suppressed.

The pipe joint <NUM> of the present exemplary embodiment has the same configuration on either side of the bend section <NUM>, namely on both the first straight section <NUM> side and the second straight section <NUM> side. Thus, there is no directionality when attaching pipes to the pipe joint <NUM>, thereby enabling fluid to flow smoothly from one pipe <NUM> to the other pipe <NUM>, and also enabling fluid to flow smoothly from the other pipe <NUM> to the one pipe <NUM>.

The adapter <NUM> is molded as a separate component to the joint body <NUM>, and may be attached to the joint body <NUM> post-production. Thus, unlike in the Background Art, there is no operation to position and preset an insert in the joint body <NUM> molding process, thereby enabling the effort required to mold the joint body <NUM> to be reduced.

Moreover, the joint body <NUM> of the present exemplary embodiment forms a bending flow path in which the bend inner side and the bend outer side are both curved faces. Thus, there is no need to provide the mold with a pin with a complex structure in which a curve-shaped movable block is provided at a leading end thereof, thereby enabling the joint body <NUM> to be molded using a mold with a simple structure.

Furthermore, although the bending flow path <NUM> of the bend section <NUM> has a substantially elliptical shaped cross-section profile perpendicular to its axial line, the adapters <NUM> are inserted into the first straight section <NUM> and the second straight section <NUM>, such that the protrusions <NUM> of the adapters <NUM> are disposed at the portion where the cross-section profile of the bending flow path <NUM> has a non-semicircular shape. This enables a flow path with a circular cross-section (a true circle) to be formed inside the bend section <NUM> by the curved bend-outer-side curved flow-path face 38B configuring part of an inner wall face of the bend section <NUM> with a semicircular cross-section profile perpendicular to its axis, and by inner peripheral faces of the protrusions <NUM> that each have a semicircular cross-section profile.

When the pipes <NUM> are respectively inserted into the first straight section <NUM> and the second straight section <NUM> of the pipe joint <NUM> in the manner described above, the flow path with a circular cross-section profile inside one of the pipes <NUM> and the flow path with a circular cross-section profile inside the other of the pipes <NUM> are connected through the circular cross-sectioned flow path inside the bend section <NUM> that has the same circular cross-section profile and is formed with the same internal diameter as the pipes <NUM>. This enables water to flow smoothly from the first straight section <NUM> side toward the second straight section <NUM>, and from the second straight section <NUM> side toward the first straight section <NUM>, and also enables an increase in pressure loss occurring in cases in which the flow path bends and the cross-section profile of the flow path changes at the bend section (changes from a circular cross-section to an elliptical cross-section) to be suppressed.

Next, explanation follows regarding a pipe joint <NUM> according to a second exemplary embodiment, with reference to <FIG>. Note that configuration that is the same as that in the first exemplary embodiment is allocated the same reference numerals, and explanation thereof is omitted.

As illustrated in <FIG>, the pipe joint <NUM> of the present exemplary embodiment is a T-shaped one-touch joint referred to as Tee pipe joint.

The pipe joint <NUM> is formed with line symmetry on either side of the second straight section <NUM>, and includes a T-shaped joint body <NUM>. A third straight section <NUM> with the same structure as the first straight section <NUM> is formed so as to face in the opposite direction to the first straight section <NUM> on the opposite side of the joint body <NUM> to the first straight section <NUM>. A corner <NUM> is thereby formed by the orthogonal second straight section <NUM> and third straight section <NUM> inside the joint body <NUM>.

Note that whereas an extension direction of the first straight section <NUM> is an arrow R direction (a first direction), an extension direction of the third straight section <NUM> is an arrow L direction (a second direction) that is the opposite direction to the arrow R direction. An extension direction of the second straight section <NUM> is an arrow U direction (a third direction) that is orthogonal to both the arrow R extension direction of the first straight section <NUM> and the arrow L extension direction of the third straight section <NUM>.

A pair of protrusions <NUM> that both face in opposite directions to a radial direction are provided to an adapter <NUM> of the present exemplary embodiment that is inserted into the second straight section <NUM>.

When the adapter <NUM> is inserted into the second straight section <NUM>, the protrusion <NUM> of the adapter <NUM> inserted into the third straight section <NUM> and one of the protrusions <NUM> of the adapter <NUM> inserted into the second straight section <NUM> are disposed adjacent to the corner <NUM> so as to cover the corner <NUM>, and a curving curved flow-path inner wall face is formed by the inner peripheral faces 50A of the respective protrusions <NUM>.

This enables water to flow smoothly from the second straight section <NUM> side toward the third straight section <NUM> side, and from the third straight section <NUM> side toward the second straight section <NUM> side, thereby enabling pressure loss to be reduced in this case also. In particular, a smoothly curving (corner-less) flow path cannot be formed to the pipe joint <NUM> formed with a T-shape referred to as a Tee pipe joint by injection molding. Thus, the advantageous effects of applying the present disclosure to the present exemplary embodiment are great, in other words a configuration in which the present exemplary embodiment is applied with the present disclosure is highly advantageous.

Although exemplary embodiments of the present disclosure have been described above, the present disclosure is not limited to the above description, and obviously various other modifications may be implemented within a range that lies within the scope of the claims.

In the first exemplary embodiment, an example was described in which the present disclosure was applied to an L-shaped pipe joint <NUM> referred to as an elbow pipe j oint, whereas in the second exemplary embodiment, an example was described in which the present disclosure was applied to an T-shaped pipe joint <NUM> referred to as a Tee pipe joint. However, the present disclosure may be applied to joints other than elbow or Tee joints, such as a cross-shaped pipe joint, and may be applied to flow path structures other than pipe joints, such as a pipe that simply bends. As an example of a cross-shaped pipe joint, the pipe joint of the second exemplary embodiment may be provided with a fourth straight section with the same configuration as the second straight section <NUM> on the opposite side to the second straight section <NUM>.

Although an angle formed by the first straight section <NUM> and the second straight section <NUM> is <NUM>° in the pipe joint <NUM> of the first exemplary embodiment, an angle other than <NUM>° may be formed.

The joint body <NUM> may be molded using a transparent synthetic resin such that presence or absence of the adapter <NUM> is easily determined from the exterior.

Although the pipe joint <NUM> of the above exemplary embodiment is what is referred to as a one-touch joint in which the pipe <NUM> is held in place simply by being inserted, the configuration of the connecting section to the pipe <NUM> is not limited to the configuration of the above exemplary embodiment. Another, conventionally known configuration (such as screw fastening) may be applied.

Although the adapter <NUM> of the above exemplary embodiments includes the circular tube shaped main body <NUM>, as long as at the least protrusion <NUM> is provided, the main body <NUM> does not necessarily have to be provided. Alternatively, the main body <NUM> may be configured by half of a circular tube shape.

Although the protrusions <NUM> for retaining the adapter <NUM> in the joint body <NUM> are provided to the main body <NUM> in the pipe joint <NUM> of the above exemplary embodiment, the protrusions <NUM> and the grooves <NUM> in the joint body <NUM> may be omitted if not required.

The adapter <NUM> described above is a molded component made of synthetic resin, and as an example, may be molded using a mold <NUM> such as that illustrated in <FIG>.

The mold <NUM> is provided with a recess 62A for forming an outer side of the adapter <NUM>. The mold <NUM> is also provided with a first slider pin <NUM> for forming an inner side of the main body <NUM> of the adapter <NUM>, and a second slider pin <NUM> for forming an inner side of the protrusion <NUM> and the circular hole <NUM>, these slider pins being capable of moving in and out of the mold <NUM>. Note that as an example, the mold <NUM> is capable of being divided into two parts in either an up-down direction in <FIG>, or a depth direction of the page in <FIG>.

Molten synthetic resin is injected into the recess 62A in the mold <NUM> and into a cavity formed by the first slider pin <NUM> and the second slider pin <NUM>. After the synthetic resin has cooled, the first slider pin <NUM> and the second slider pin <NUM> are removed and the mold <NUM> is opened up to obtain the adapter <NUM>.

Claim 1:
A flow path structure that connects together a plurality of flow paths each extending in a different direction, the flow path structure comprising:
a joint body (<NUM>) comprising a flow-path inner corner (38A) formed at a connecting section between one of the flow paths and another of the flow paths; and
an adapter (<NUM>) disposed adjacent to the flow-path inner corner (38A) so as to couple together the one of the flow paths and the other of the flow paths, at a curving curved flow-path inner wall face,
wherein:
the adapter (<NUM>) includes a protrusion (<NUM>) that projects toward a flow path inner side so as to form the curved flow-path inner wall face;
a retainer portion (<NUM>) is provided at the adapter;
a retaining portion (<NUM>) that engages with the retainer portion (<NUM>) so as to retain the adapter (<NUM>) inside the flow path is provided at a flow path inner face;
the adapter (<NUM>) includes a tubular section (<NUM>) for insertion into the flow path;
the protrusion (<NUM>) is provided at one axial direction end side of the tubular section (<NUM>);
the retainer portion (<NUM>) is provided at an outer peripheral portion of the tubular section (<NUM>); characterized in that
the retainer portion (<NUM>) comprises a pair of protrusions (<NUM>) that extend along the axial direction and are formed to an outer peripheral portion of the tubular section (<NUM>) which forms a main body (<NUM>) of the adapter (<NUM>);
a retaining portion (<NUM>) comprises a pair of grooves (<NUM>) that extend along an axial line direction and are formed in a housing area (<NUM>) of the joint body (<NUM>) where the main body (<NUM>) is inserted, and
the protrusions (<NUM>) of the adapter (<NUM>) engage with the grooves (<NUM>).