JP3620508B2 - Tube connection structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tube connecting structure, and more particularly to a tube connecting structure constituting a hydraulic circuit.
[0002]
[Prior art]
As is well known, a so-called bridge flare type is known as a coupling structure of this type of tube.
[0003]
FIG. 6 shows a bridge flare-type tube connecting structure. In FIG. 6, a hole 101a is formed in the union 101, and a screw groove is formed on the inner peripheral surface of the hole 101a. A thread is also engraved on the outer peripheral surface of the flare nut 102, and the flare nut 102 is screwed into the hole 101 a of the union 101. The tube 103 passes through the through hole 102a of the flare nut 102, and has a flare 104 at the tip. The flare portion 104 is formed by slightly expanding the diameter near the tip of the tube body 103, projecting the entire circumference near the tip to the outside, narrowing the tip, and projecting the tip in the longitudinal direction.
[0004]
When the flare 104 is inserted into the hole 101a together with the flare nut 102 and the flare nut 102 is tightened, the flare 104 is sandwiched between the tip of the flare nut 102 and the back wall 101b of the hole 101a, and the tube 103 is unioned. 101.
[0005]
[Problems to be solved by the invention]
By the way, the conventional flare portion 104 has a substantially U-shaped peripheral wall longitudinal section, and is elastically deformed in the longitudinal direction (axial direction) of the tube body 103. The elastic deformation of the flare 104 has been considered to bring the tip of the flare 104 and the back wall 101b into good contact.
[0006]
However, in the actual work process, the flare nut 102 is tightened excessively, and as shown in FIG. 7, the flare portion 104 is plastically deformed, and the annular inner circumferential groove 104a is crushed in the longitudinal direction. In some cases, the end surface 104b of the flare 104 is in contact with the back wall 101b instead of the tip of the 104. In this case, since the contact area between the flare part 104 and the back wall 101b increases, it was a result that did not meet the requirement of improving the sealing performance between the two.
[0007]
When the flare 104 is sandwiched between the tip of the flare nut 102 and the inner wall 101b of the hole 101a, the flare 104 rotates together with the flare nut 102, and the flare 104 is rotated. If the flare nut 102 is continuously tightened until the inner circumferential groove 104a of the flare part 104 is completely crushed after the flare part 104 is sandwiched, the rotation angle of the flare part 104 due to rotation becomes so large that it cannot be ignored. 103 may be greatly twisted.
[0008]
Furthermore, a low friction agent (preton oil) may be applied between the inner periphery of the hole 101a of the union 101 and the outer periphery of the flare nut 102 in order to ensure the sealing performance between the tube 103 and the union 101. In this case, a low-friction agent coating step is required, resulting in an increase in cost. In addition, this low friction agent may adhere to the tip of the flare 104 and the friction between the flare 104 and the back wall 101b may be reduced. At this time, the flare 104 will slide relative to the back wall 101b. And the flare part 104 became easy to rotate with the flare nut 102, and the twist of the pipe body 103 became large.
[0009]
In addition, when the surface treatment of the union 101 is performed, the back wall 101b is masked to remove the back wall 101b from the surface treatment target, and the friction between the flare 104 and the back wall 101b is reduced by the surface treatment of the back wall 101b. Thus, although it is prevented that the flare 104 is easily rotated, a masking process is required, which causes an increase in cost and remains uneasy about the reliability of the masking.
[0010]
On the other hand, at the base portion of the conventional flare 104, the curvature of the peripheral wall 103a of the tube 103 is constant and large. When the curvature of the peripheral wall 103a is large, when the flare nut 102 is strongly tightened, a large tensile stress P is generated in the peripheral wall 103a, and this tensile stress P remains until later. In the peripheral wall 103a at the base portion of the tubular body 103 where the tensile stress P remains, it is difficult to ensure its mechanical strength.
[0011]
Further, if the curvature of the peripheral wall 103 a of the tube body 103 is large, the stress tends to concentrate on the base portion of the flare portion 104 when an external force is applied to the tube body 103.
[0012]
If the curvature of the peripheral wall 103a at the base portion of the flare 104 is large in this way, the tensile stress P tends to remain, it is difficult to ensure mechanical strength, and the stress tends to concentrate. As a result, it was difficult to ensure the durability of the peripheral wall 103a at the base of the flare 104.
[0013]
Therefore, the present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a tubular structure in which a flare portion is difficult to be plastically deformed.
[0014]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention increases the diameter of a tubular body in the vicinity of the distal end of the tubular body, protrudes the entire circumference in the vicinity of the distal end of the tubular body, and the distal end of the tubular body. A throttle, a flared portion in which the tip of the tubular body protrudes in the longitudinal direction of the tubular body, and a joined body coupled to the tubular body by being tightened and pressed with a flare nut at the distal end of the flared portion When the tip of the flare is pressed against the member to be joined in a state where the tip of the tube is squeezed to hold the flare shape projected in the longitudinal direction of the tube In addition, the inner circumferential groove width (opening width in the longitudinal direction of the tube) formed on the inner side of the flare portion at the entire circumferential portion protruding outside the flare portion is not substantially displaced. narrowing the width, in the longitudinal direction of the flared portion for tightening torque of the flare nut By reducing the shape amount, the flared portion has a plastic deformation hardly shape at the longitudinal direction of the tube.
[0015]
According to the present invention having such a configuration, when the tip of the flare is pressed against the coupled body in a state where the tip of the tube is squeezed and the flare part shape projected in the longitudinal direction of the tube is maintained, The width of the inner peripheral groove formed on the inner side of the flare portion is reduced so that the inner peripheral groove is not substantially displaced, and the deformation amount in the longitudinal direction of the flare portion with respect to the tightening torque of the flare nut is reduced. The flare has a shape that is difficult to plastically deform in the longitudinal direction of the tubular body . For this reason, even if the tip of the flare portion of the tubular body is strongly pressed against the coupled body, the flare portion is hardly plastically deformed in the longitudinal direction of the tubular body, and the contact area between the flare portion and the coupled body is difficult to increase. The surface pressure (sealability) between the two does not decrease. Moreover, when pressing the flare part of a pipe body to a to-be-joined body with a flare nut, it is possible to reduce twisting of the pipe body by reducing the rotation of the flare part with the flare nut.
[0016]
Further, the present invention increases the diameter of the tubular body in the vicinity of the distal end of the tubular body, protrudes the entire circumference near the distal end of the tubular body, and squeezes the distal end of the tubular body. Coupling of a tubular body comprising a flared portion having a distal end projecting in the longitudinal direction of the tubular body, and a joined body coupled to the tubular body by pressing the distal end of the flared portion with a flare nut being pressed. In the structure, the tip of the tube body is narrowed down and the flare portion shape projected in the longitudinal direction of the tube body is maintained, and the entire peripheral portion projecting outside the flare portion is formed inside the flare portion. The inner circumferential groove width is made substantially zero, and the inner diameter of the inner circumferential groove, which maintains substantially zero, is made smaller than the outer diameter of the tube body, and the flare nut is tightened in the longitudinal direction of the flare portion with respect to the tightening torque. The shape of the flare is difficult to plastically deform in the longitudinal direction of the tube And the.
[0017]
Here, the inner peripheral groove formed on the inner side of the flare portion at the entire peripheral portion that protrudes to the outside of the flare portion in a state where the flare portion shape is held by narrowing the tip of the tube body and protruding in the longitudinal direction of the tube body The inner diameter of the inner circumferential groove that makes the width of the tube substantially zero and maintains substantially zero is smaller than the outer diameter of the tube body, and the amount of deformation in the longitudinal direction of the flare portion with respect to the tightening torque of the flare nut The flare portion has a shape that is difficult to be plastically deformed in the longitudinal direction of the tubular body . For this reason, even when strongly pressed tube of the tip of the flared portion to be conjugate with flared portion is less likely to plastically deform at the longitudinal direction of the tube, the contact area of the flared part and the conjugate is increased It is difficult to reduce the surface pressure (sealability) between the two. Moreover, when pressing the flare part of a pipe body to a to-be-joined body with a flare nut, it is possible to reduce twisting of the pipe body by reducing the rotation of the flare part with the flare nut.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
[0019]
FIG. 1 shows an embodiment of a tube connecting structure according to the present invention. In FIG. 1, a hole 11a is formed in the union 11, and a screw groove is formed on the inner peripheral surface of the hole 11a. A thread is also engraved on the outer peripheral surface of the flare nut 12, and the flare nut 12 is screwed into the hole 11 a of the union 11. The tubular body 13 passes through the through-hole 12a of the flare nut 12, and has a flare portion 14 at the tip. The flare portion 14 is formed by slightly expanding the diameter near the tip of the tube body 13 so that the entire circumference near the tip protrudes outward, the tip is narrowed, and the tip protrudes in the longitudinal direction.
[0020]
When the flare part 14 is inserted into the hole 11a together with the flare nut 12 and the flare nut 12 is tightened, the flare part 14 is sandwiched between the tip of the flare nut 12 and the back wall 11b of the hole 11a, and the tube body 13 is a union. 11.
[0021]
As shown in FIG. 2, the flare portion 14 is enlarged in the vicinity of the distal end of the tubular body 13, further narrowed down the distal end of the tubular body 13, and protruded in the longitudinal direction of the tubular body 13. . An annular inner circumferential groove 14a is formed inside the flare portion 14, but the width of the inner circumferential groove 14a (the opening width in the longitudinal direction of the tube 13) is substantially zero except for the inner diameter portion. Has been. Further, the inner diameter r1 of the inner circumferential groove 14a whose width is substantially zero is made smaller than the outer diameter r2 of the tube body 13.
[0022]
In addition, the peripheral wall 13a of the tubular body 13 is continuously and smoothly bent inside the flare portion 14, and the curvature of the peripheral wall 13a is increased as the distance from the outer diameter of the tubular body 13 increases. On the contrary, the curvature of the peripheral wall 13a is made small near the outer diameter of the tubular body 13, that is, at the root portion of the flare portion 14. That is, the peripheral wall 13a of the tube body 13 is not bent with a constant curvature, but is bent so as to be farther from the outer diameter of the tube body 13, and conversely, it is gently bent at the base portion of the flare portion 14.
[0023]
Furthermore, the peripheral wall 12a of the flare nut 12 is not bent at a constant curvature at the tip of the flare nut 12, and is bent more greatly as it approaches the tip of the flare nut 12, and conversely, it is gently bent as it gets farther away. With such a shape of the flare nut 12, the tip of the flare nut 12 does not bite into the base portion of the flare part 14, and the contact portion between the tip of the flare nut 12 and the flare part 14 approaches the tube body 13. .
[0024]
Thus, in this embodiment, since the width of the inner peripheral groove 14a of the flare portion 14 is substantially zero, even if the flare nut 12 is strongly tightened, the inner peripheral groove 14a is not deformed due to plastic deformation of the flare portion 14. It will not be crushed. For this reason, even if it strongly presses the front-end | tip part 14b of the flare part 14 against the back wall 11b, the contact area between both does not increase rapidly and the surface pressure (sealing property) between both can be kept high. No liquid leakage occurs between them. Substantially zero means the width of the inner circumferential groove 14a such that the width of the inner circumferential groove 14a hardly changes even when the flare nut 12 is strongly tightened, and is not limited to 0 mm. It depends on the thickness, material, etc.
[0025]
Moreover, even if the flare nut 12 is strongly tightened after the flare portion 14 is sandwiched between the tip of the flare nut 12 and the back wall 11b, the amount of plastic deformation of the flare portion 14 is small, so that it rotates together with the flare nut 12. The rotation angle of the flare portion 14 is small, and the tube 13 is hardly twisted.
[0026]
In addition, since the liquid tightness between the distal end portion 14b of the flare portion 14 and the back wall 11b can be kept high, the hole 11a of the union 11 and the flare nut are secured in order to ensure the sealing performance between the tube body 13 and the union 11. It is not necessary to apply the low friction agent between the two, and the application process can be omitted to reduce the cost.
[0027]
Furthermore, even if the surface treatment is applied to the back wall 11b and the friction between the flare portion 14 and the back wall 11b is reduced, the tip portion 14b of the flare portion 14 is securely pressed against the back wall 11b, and the surface between the two Since the pressure is kept high, there is no need to mask the back wall 11b during the surface treatment of the union 11 as in the prior art, which can reduce the cost, and there is also anxiety about the reliability of the masking. Disappear.
[0028]
FIG. 3 is a graph showing the amount of deformation of the flare when the flare nut is tightened in comparison with the present embodiment and a conventional example. In this graph, the horizontal axis indicates the tightening torque, the vertical axis indicates the amount of deformation of the flare portion (the amount of deformation in the direction along the longitudinal direction of the tubular body), and the solid line A indicates the flare portion in the present embodiment. The dotted line B shows the deformation amount characteristic of the flare portion in the conventional example. As is apparent from this graph, the amount of deformation of the flare portion with respect to the tightening torque of the flare nut is smaller in the present embodiment.
[0029]
On the other hand, when the flare nut 12 is strongly tightened and the tip 14b of the flare 14 is strongly pressed against the back wall 11b, the tensile stress P is applied to the peripheral wall 13a of the tube 13 on the right side of the flare 14 as shown in FIG. Occur. However, the peripheral wall 13 a is gently bent at the base portion of the flare portion 14. In the base portion having a small curvature, the tensile stress P with respect to the peripheral wall 13a is small, and the tensile stress P is dispersed, so that there is almost no deterioration in mechanical strength. In addition, at the base portion having a small curvature, when an external force is applied to the tube body 13, the external force is difficult to concentrate on the peripheral wall 13 a. As described above, since the mechanical strength of the base portion of the flare portion 14 is hardly deteriorated and the external force is hardly concentrated on the base portion, the durability of the peripheral wall 13a can be secured at the base portion.
[0030]
Further, as described above, the shape of the flare nut 12 is devised to bring the contact portion between the tip of the flare nut 12 and the flare portion 14 closer to the tube body 13. Also by this, it has been empirically known that the tensile stress P of the peripheral wall 13a is small at the base portion of the flare portion 14, and the deterioration of the mechanical strength of the base portion of the flare portion 14 is reduced.
[0031]
Further, the shape of the contact portion between the tip of the flare nut 12 and the flare part 14 is set so that the contact area between the tip of the flare nut 12 and the flare part 14 is widened. Thereby, the surface pressure of the contact portion is suppressed.
[0032]
FIG. 4 is a graph showing the mechanical strength of the base portion of the flare part in comparison with the present embodiment and a conventional example. In this graph, the horizontal axis indicates the number of tube amplitudes (number of repetitions of fracture), and the vertical axis indicates the amplitude (stress amplitude) of the tube, and the solid line C indicates the root portion of the flare portion in the present embodiment. Indicates the number of amplitudes and amplitudes when the rupture is broken, and a dotted line D indicates the number of amplitudes and amplitudes when the base portion of the flare portion in the conventional example is broken. When this embodiment is compared with a conventional example, the strength of this embodiment is increased by 35 percent.
[0033]
FIG. 5 schematically shows an automobile brake system to which the tubular structure of the embodiment of FIG. 1 is applied. In FIG. 5, the ABS actuator 21 is fixed to the body of the automobile via a plurality of rubbers 22, and each rubber 22 prevents the vibration sound of the ABS actuator 21 from being transmitted to the body. Moreover, the pressure oil is supplied to the ABS actuator 21 through the tubular body coupling structure of the present embodiment. The tube 13 is fixed to the body of the automobile by a bracket 23.
[0034]
In such a configuration, when vibration is generated in the body of the automobile, the ABS actuator 21 and the pipe body 13 supported via the rubbers 22 vibrate separately, so that the ABS actuator 21 and the pipe body 13 are vibrated separately. Relative displacement increases. A gap 15 exists between the tube body 13 and the flare nut 12. For this reason, the vibration of the tubular body 13 is transmitted to the base portion of the flare portion 14, and the base portion of the flare portion 14 is repeatedly subjected to tensile stress and compressive stress, that is, vibration is generated. However, in the tubular body coupling structure of the present embodiment, as described above, there is little deterioration in the mechanical strength of the peripheral wall 13a at the base portion of the flare portion 14, and it is difficult for external forces to concentrate on the base portion. The durability of the peripheral wall 13a can be ensured.
[0035]
In other words, the vibration of the tube 13 can be allowed to some extent. For this reason, the spring constant of each rubber 22 can be lowered to improve the performance of blocking vibration noise from the ABS actuator 21 to the body, the number of brackets 23 can be reduced, and the brackets 23 can be made smaller. In an automobile brake system, since the number of pipes is large and there are many connection points, if the number and size of the brackets 23 are improved by applying the pipe connection structure of this embodiment, the cost can be reduced. Significant reduction can be achieved. Of course, since this embodiment can be applied not only to the brake system but also to other hydraulic transmission systems and fuel transmission systems, the overall cost reduction effect is great.
[0036]
In addition, the coupling structure of the tubular body of the present invention is not applied only to the coupling of piping of a vehicle such as an automobile, and any other structure can be used as long as the end of the tubular body is coupled to the coupled body. Can be applied. Moreover, the non-metallic thing may be used for the pipe body used as connection object.
[0037]
【The invention's effect】
As described above, according to the present invention, when the tip of the flare is pressed against the coupled body in a state where the tip of the pipe is squeezed and the flare shape is protruded in the longitudinal direction of the tube, The width of the inner peripheral groove formed on the inner side of the flare portion is reduced so that the inner peripheral groove is not substantially displaced, and the deformation amount in the longitudinal direction of the flare portion with respect to the tightening torque of the flare nut is reduced. The flare has a shape that is difficult to plastically deform in the longitudinal direction of the tubular body. For this reason, even if the tip of the flare portion of the tubular body is strongly pressed against the coupled body, the flare portion is hardly plastically deformed in the longitudinal direction of the tubular body, and the contact area between the flare portion and the coupled body is difficult to increase. The surface pressure (sealability) between the two does not decrease. Moreover, when pressing the flare part of a pipe body to a to-be-joined body with a flare nut, it is possible to reduce twisting of the pipe body by reducing the rotation of the flare part with the flare nut.
[0038]
In addition, according to the present invention, in a state where the flare portion shape is squeezed and protruded in the longitudinal direction of the tube body by holding the tip of the tube body, it is formed on the inner side of the flare portion at the entire peripheral portion protruding outside the flare portion. The width of the inner circumferential groove is substantially zero, and the inner diameter of the inner circumferential groove, which is substantially zero, is made smaller than the outer diameter of the tube, and the length of the flare portion with respect to the tightening torque of the flare nut The amount of deformation in the direction is reduced, and the narrowed tip portion of the flare portion has a shape that is difficult to plastically deform in the longitudinal direction of the tubular body . For this reason, even if the tip of the flare portion of the tubular body is strongly pressed against the coupled body, the flare portion is hardly plastically deformed in the longitudinal direction of the tubular body, and the contact area between the flare portion and the coupled body is difficult to increase. The surface pressure (sealability) between the two does not decrease. Moreover, when pressing the flare part of a pipe body to a to-be-coupled body with a flare nut, it is possible to reduce twisting of the pipe body by reducing the rotation of the flare part with the flare nut.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an embodiment of a tubular body coupling structure according to the present invention.
FIG. 2 is an enlarged view of a main part of FIG.
FIG. 3 is a graph showing the amount of deformation of a flare portion when a flare nut is tightened in comparison with this embodiment and a conventional example.
FIG. 4 is a graph showing the mechanical strength of the base part of the flare part in comparison with the present embodiment and a conventional example.
FIG. 5 is a diagram schematically showing a brake system for an automobile to which the tubular structure of FIG.
FIG. 6 is a longitudinal sectional view showing a conventional bridge flare type tube connecting structure.
7 is a longitudinal sectional view showing a state of plastic deformation of a flare portion in the tubular body coupling structure of FIG. 6;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Union, 12 ... Flare nut, 13 ... Tube, 14 ... Flare part, 14a ... Inner peripheral groove of flare part, 14b ... Tip part of flare part, 21 ... ABS actuator, 22 ... Rubber, 23 ... Bracket

Claims (3)

The diameter of the tubular body is enlarged near the distal end of the tubular body, the entire circumference near the distal end of the tubular body is projected outward, the distal end of the tubular body is squeezed, and the distal end of the tubular body is In a coupling structure of a tubular body comprising a flare portion that protrudes in the longitudinal direction, and a joined body that is coupled to the tubular body by being pressed and tightened with a flare nut at the tip of the flare portion,
When the tip of the tube body is squeezed and the flare portion shape projected in the longitudinal direction of the tube body is maintained, when the tip of the flare portion is pressed against the coupled body, the tube body protrudes outside the flare portion. The width of the inner circumferential groove is narrowed so that the width of the inner circumferential groove formed on the inner side of the flare portion is not substantially displaced at the entire circumferential portion, and the longitudinal direction of the flare portion with respect to the tightening torque of the flare nut A tubular structure for connecting the tubular body in which the amount of deformation is reduced so that the flare portion is difficult to plastically deform in the longitudinal direction of the tubular body. The diameter of the tubular body is enlarged near the distal end of the tubular body, the entire circumference near the distal end of the tubular body is projected outward, the distal end of the tubular body is squeezed, and the distal end of the tubular body is In a coupling structure of a tubular body comprising a flare portion that protrudes in the longitudinal direction, and a joined body that is coupled to the tubular body by being pressed and tightened with a flare nut at the tip of the flare portion,
An inner circumference formed on the inner side of the flare portion at the entire circumference projecting to the outside of the flare portion in a state where the flare portion shape which is squeezed at the tip of the tube body and protruded in the longitudinal direction of the tube body is maintained. The inner diameter of the inner circumferential groove that makes the width of the groove substantially zero and maintains substantially zero is smaller than the outer diameter of the tube body, and the flare nut in the longitudinal direction with respect to the tightening torque of the flare nut A coupling structure for a tubular body in which the amount of deformation is reduced and the flare portion has a shape that is difficult to plastically deform in the longitudinal direction of the tubular body. The diameter of the tubular body is enlarged near the distal end of the tubular body, the entire circumference near the distal end of the tubular body is projected outward, the distal end of the tubular body is squeezed, and the distal end of the tubular body is In a coupling structure of a tubular body comprising a flare portion that protrudes in the longitudinal direction and a coupled body that is coupled to the tubular body by pressing the tip of the flare portion.
  An inner circumference formed on the inner side of the flare portion at the entire circumference projecting to the outside of the flare portion in a state where the flare portion shape which is squeezed at the tip of the tube body and protruded in the longitudinal direction of the tube body is maintained. A tubular structure in which the width of the groove is zero and the inner diameter of the inner circumferential groove that maintains zero is smaller than the outer diameter of the tubular body.

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