Fastening structure and fastening method

Abstract

To provide a fastening structure which can prevent co-rotation of a seal member, such as an O ring, and prevent deterioration of sealability of a case internal hydraulic circuit communicating (connected) through a mating surface when entire peripheries of mating surfaces of a first case and a second case are formed as screw structures and fastened to each other by thread engagement.SOLUTION: In a fastening structure 1, a retainer 20 is set in a cylindrical recessed part 120 formed on a mating surface of a first case 101 in a state that an O ring 30 is held by the retainer 20 and stoppers 202 are closed to the inner side in a radial direction and the first case 101 (a female screw 1011) and a second case 102 (a male screw 1021) are threadedly engaged to be fastened. Then, projection parts 201 receive a hydraulic pressure to move to the mating surface side of the opposing second case 102. When the projection parts 201 get over a step part 130, the stoppers 202 open to be engaged with a top surface of the step part 130.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a fastening structure for fastening a plurality of cases and a fastening method using the fastening structure.

Background Art

[0002] For example, Patent Document 1 discloses a housing of a transmission in which a first case and a second case are fastened by a plurality of bolts. In this housing, the case on the head side of the bolt among the first case or the second case has a seat surface with which the head abuts and a shaft hole having a shape in which at least a part around the shaft portion of the bolt is hollowed out. Therefore, it is possible to secure the surface pressure of the mating surface without causing an increase in the number of parts (number of bolts) or an increase in weight.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, instead of fastening with a plurality of bolts, for example, a structure in which the entire circumference of the mating surface between the first case and the second case of a transmission is formed as a screw structure and the two are fastened by screwing them together (that is, a fastening structure that generates surface pressure with axial force) can be considered.

[0005] However, for example, when a hydraulic circuit is formed inside both cases and the in-case hydraulic circuit is deviated (displaced) from the central axis of the case, if an O-ring is used to seal the connection portion (mating surface) of the in-case hydraulic circuit, the O-ring may be rotated when the two cases are screwed together. And due to the rotation, there is a risk that the O-ring will be twisted or cut, and the sealing performance may be impaired.

[0006] The present invention has been made to solve the above problems, and when fastening both by screwing the entire circumference of the mating surface of the first case and the second case as a screw structure, it is possible to prevent the rotation of a seal member such as an O-ring, thereby preventing the sealing performance of the in-case hydraulic circuit communicated (connected) through the mating surface from being impaired. An object of the present invention is to provide a fastening structure and a fastening method using the fastening structure.

Means for Solving the Problems

[0007] The fastening structure according to one aspect of the present invention includes a first case in which a female screw is formed on the inner peripheral surface of the case connected to the mating surface, and a first hydraulic circuit with an end exposed on the mating surface is formed inside; a second case in which a male screw capable of screwing with the female screw of the first case protrudes on the mating surface, and a second hydraulic circuit with an end exposed on the mating surface and communicable with the first hydraulic circuit is formed inside; a retainer formed in an annular shape, with a protruding portion protruding radially inward formed on the inner peripheral surface and a plurality of stoppers having radial flexibility formed on the outer peripheral surface; and an annular seal member disposed between the retainer held by the retainer and the mating surface of the case facing the retainer. A cylindrical recess into which the retainer holding the seal member fits is formed around the end of the first hydraulic circuit exposed on the mating surface of the first case or around the end of the second hydraulic circuit exposed on the mating surface of the second case. Along the inner surface connected to the inner bottom surface of the cylindrical recess, a step portion is formed that protrudes radially inward of the cylindrical recess and restricts the axial movement of the retainer when engaged with the stopper of the retainer. The dimension from the mating surface to the bottom surface of the cylindrical recess is set higher than the total height of the retainer including the held seal member, and the dimension from the mating surface to the top surface of the step portion of the cylindrical recess is set lower than the total height of the retainer including the held seal member. The retainer holds the seal member and is set in the cylindrical recess formed on the mating surface of the first case or the second case with the stopper closed radially inward. After the first case and the second case are screwed and fastened, the protruding portion receives hydraulic pressure and moves toward the mating surface side of the opposing case, and when it exceeds the step portion, the stopper opens and is locked to the top surface of the step portion.

[0008] According to the fastening structure according to one aspect of the present invention, the dimension (depth) from the mating surface to the bottom surface of the cylindrical recess is set higher than the total height (axial dimension) of the retainer including the held seal member, and the retainer holds the seal member and is set in the cylindrical recess formed in the first case or the second case with the stopper closed inward in the radial direction, and the first case and the second case are screwed together. Therefore, the seal member does not come into contact with the mating surface of the case facing it, and it is possible to prevent the seal member from being rotated when the cases are screwed together.

[0009] Also, the dimension (depth) from the mating surface to the top surface of the stepped portion of the cylindrical recess is set lower than the total height (axial dimension) of the retainer including the held seal member, and after the first case and the second case are screwed together and fastened, the protrusion receives hydraulic pressure and the retainer moves toward the mating surface side of the opposing case, and when it exceeds the stepped portion, the stopper opens and is locked to the top surface of the stepped portion. Therefore, the connection portion (connection point) between the first hydraulic circuit and the second hydraulic circuit can be sealed by the seal member.

Advantages of the Invention

[0010] According to the present invention, when fastening both the first case and the second case by screwing the entire circumference of the mating surface with a screw structure, it is possible to prevent the seal member such as an O-ring from being rotated, and thus it is possible to prevent the sealing performance of the in-case hydraulic circuit communicated (connected) through the mating surface from being impaired.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0012] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Unless otherwise particularly distinguished, the same reference numerals will be used for the same or corresponding parts in the drawings. Also, in each figure, the same elements will be denoted by the same reference numerals and redundant explanations will be omitted.

[0013] First, with reference to FIGS. 1 and 2 together, the configuration of the fastening structure 1 according to the embodiment will be described. FIG. 1 is a cross-sectional view showing the fastening structure 1. FIG. 2 is an enlarged cross-sectional view showing the main part of the fastening structure 1 (the part surrounded by the broken line in FIG. 1).

[0014] In the present embodiment, as the fastening structure 1, the case where it is applied to a transmission case will be described as an example. More specifically, as the fastening structure 1, a structure for fastening the first case 101 and the second case 102 that constitute a transmission case 10 accommodating a transmission mechanism including a hydraulic circuit (fastening structure of the transmission case) will be described as an example.

[0015] The fastening structure 1 is a structure in which the entire circumference of the mating surface between the first case 101 and the second case 102 that constitute the transmission case 10 is a screw structure, and the two are fastened by screwing (that is, a fastening structure that generates surface pressure with axial force). In particular, when the fastening structure 1 fastens the entire circumference of the mating surface of the first case 101 and the second case 102 by screwing with a screw structure, it can prevent the O-ring 30 from rotating, thereby preventing the sealing performance of the in-case hydraulic circuit 110 communicated (connected) through the mating surface from being impaired.

[0016] Therefore, the fastening structure 1 mainly includes the first case 101, the second case 102, the retainer 20, and the O-ring 30 (corresponding to the sealing member described in the claims). Hereinafter, each component will be described in detail.

[0017] The first case 101 is made of a metal such as iron or aluminum, and a female thread 1011 is formed on the inner peripheral surface of the case that connects to the mating surface. Further, a first hydraulic circuit 111 whose end (end face) is exposed on the mating surface is formed inside the first case 101.

[0018] The second case 102 is made of a metal such as iron or aluminum, and a male thread 1021 that can be screwed with the female thread 1011 of the first case 101 protrudes from the mating surface. Further, a second hydraulic circuit 112 whose end (end face) is exposed on the mating surface and can communicate (connect) with the first hydraulic circuit 111 is formed inside the second case 102. Note that the case internal hydraulic circuit 110 composed of the first hydraulic circuit 111 and the second hydraulic circuit 112 formed inside both cases is disposed at a location (a displaced location) deviated from the central axis of the transmission case 10.

[0019] The retainer 20 is made of, for example, resin (engineering plastic) and is formed in an annular shape. On the inner peripheral surface of the retainer 20 (along the inner peripheral surface), a protrusion (convex portion) 201 that protrudes convexly inward in the radial direction is formed. The protrusion 201 has, for example, a triangular cross-section.

[0020] Here, the inner diameter of the retainer 20 excluding the protrusion (convex portion) 201 is formed to be substantially the same as the diameter of the first hydraulic circuit 111 and the second hydraulic circuit 112. Therefore, the protrusion 201 protrudes inward in the radial direction of the first hydraulic circuit 111 and the second hydraulic circuit 112 (that is, it serves as a throttle for the case internal hydraulic circuit 110). As a result, when hydraulic pressure (oil) is supplied through the case internal hydraulic circuit 110 after the case is fastened, the protrusion 201 receives the hydraulic pressure and generates a pressing force in the direction of the mating surface of the case on the retainer 20.

[0021] In addition, on the outer peripheral surface of the retainer 20, a plurality of stoppers (claw portions) 202 having flexibility (capable of opening and closing) in the radial direction are formed. Each stopper 202 is formed, for example, in a substantially plate shape and is attached obliquely with respect to the axial direction of the retainer 20. Further, three (or more than three) stoppers 202 are formed at equal intervals along the circumferential direction of the retainer 20.

[0022] When the retainer 20 is set in the cylindrical recess 120 of the first case 101, the stopper 202 is pushed by a jig or the like and closed radially inward. On the other hand, after the two cases are fastened, hydraulic pressure is supplied through the in-case hydraulic circuit 110, and when the retainer 20 moves in the mating surface direction and exceeds a step portion 130 described later, the stopper 202 automatically opens (returns) radially outward by elasticity.

[0023] In addition, on the top surface (upper surface) of the retainer 20, an annular recess 203 for holding (setting) an O-ring 30 described later is formed. Note that the depth (axial dimension) of the annular recess 203 is set to be less than the diameter of the O-ring 30.

[0024] The O-ring 30 (sealing member) is an annular member having a circular cross-section, has elasticity, and is formed of a rubber material or the like excellent in oil resistance, heat resistance, etc. The O-ring 30 is held on the top surface of the retainer 20 and disposed between the mating surface of the second case 102 facing the retainer 20. After the retainer 20 is locked, the O-ring 30 is disposed so as to surround the periphery of the connection portion between the first hydraulic circuit 111 and the second hydraulic circuit 112 on the mating surface of the first case 101 and the second case 102. And the O-ring 30 seals so that oil does not leak from the connection portion between the first hydraulic circuit 111 and the second hydraulic circuit 112.

[0025] Note that a liquid gasket 40 is applied to the mating surface of the first case 101 and the second case 102, and undertakes a sealing function until the retainer 20 is locked to the step portion 130 (until hydraulic pressure is applied).

[0026] Around the end of the first hydraulic circuit 111 exposed on the mating surface of the case on the side closer to the oil pump (upstream side), that is, the first case 101 in the example of this embodiment, a cylindrical recess 120 is formed in which a retainer 20 holding an O-ring 30 is set (fitted). Further, along the inner surface connected to the inner bottom surface of the cylindrical recess 120 (over the entire circumference), it protrudes radially inward of the cylindrical recess 120 (protrudes axially from the inner bottom surface when based on the inner bottom surface), and a step portion 130 is formed that restricts the axial movement of the retainer 20 when the axial top surface engages with the stopper (claw portion) 202 of the retainer 20.

[0027] Here, the dimension (depth) from the mating surface to the bottom surface of the cylindrical recess 120 is set higher than the total height of the retainer 20 including the held O-ring 30 (axial dimension including the O-ring 30). Therefore, when the held retainer 20 is set in the cylindrical recess 120 on the mating surface of the first case 101, the O-ring 30 does not contact the mating surface of the second case 102 facing it.

[0028] Also, the dimension (depth) from the mating surface to the top surface of the step portion 130 of the cylindrical recess 120 is set lower than the total height of the retainer 20 including the held O-ring 30 (axial dimension including the O-ring 30). Therefore, when the retainer 20 (stopper 202) is locked to the step portion 130, the connection portion between the first hydraulic circuit 111 and the second hydraulic circuit 112 is sealed by the O-ring 30.

[0029] Further, the inner diameter of the step portion 130 is set smaller than the outermost diameter of the retainer 20 (including the stopper 202) when the stopper (claw portion) 202 is opened radially outward, and larger than the outermost diameter of the retainer 20 (including the stopper 202) when the stopper 202 is closed radially inward. Therefore, when the stopper 202 closes (radially inward), the retainer 20 can be set on the bottom surface of the cylindrical recess 120 on the mating surface of the first case 101 (inside the step portion 130), and when the stopper 202 opens (radially outward), the retainer 20 can be locked by the step portion 130.

[0030] Note that the inner diameter of the cylindrical recess 120 formed on the mating surface of the first case 101 is set to be the same as or slightly smaller than the outermost diameter of the retainer 20 when the stopper 202 is opened radially outward.

[0031] Next, with reference to FIG. 3, the fastening method using the fastening structure 1 will be described in more detail. FIG. 3 is a diagram for explaining the fastening method (fastening method for a transmission case) using the fastening structure 1.

[0032] First, as shown in the upper part of FIG. 3, in the first step, for example, by a cylindrical jig or the like (not shown), the retainer 20 with the O-ring 30 set (held) in a state where the stopper (claw portion) 202 is closed radially inward (compressed state) is set (assembled) in the cylindrical recess 120 formed on the mating surface of the first case 101.

[0033] Next, as shown in the middle part of FIG. 3, in the second step, the first case 101 (female thread 1011) and the second case 102 (male thread 1021) are screwed together and fastened. At this time, as described above, since the O-ring 30 does not contact the mating surface of the second case 102, the O-ring 30 does not rotate.

[0034] After that (after fastening), as shown in the lower part of FIG. 3, in the third step, oil (hydraulic pressure) is supplied to the first hydraulic circuit 111 and the second hydraulic circuit 112, and hydraulic pressure is applied to the protrusion (convex portion) 201 of the retainer 20 (a pressing force toward the mating surface side is generated), and the retainer 20 moves toward the mating surface side of the second case 102 facing it. Then, oil enters the gap generated between the retainer 20 and the inner bottom surface of the cylindrical recess 120 (hydraulic pressure is applied), and while pressing the O-ring 30 against the mating surface of the second case 102 facing it, the retainer 20 moves until it crosses the step portion 130, and the stopper 202 opens and is locked to the top surface of the step portion 130.

[0035] Therefore, the retainer 20 is fixed by receiving the reaction force from the O-ring 30 (axial movement of the retainer 20 is restricted). After that, since the retainer 20 is fixed even without applying hydraulic pressure (even without oil flow), the sealing performance at the O-ring 30 is maintained.

[0036] As described in detail above, according to the present embodiment, the dimension (depth) from the mating surface to the bottom surface of the cylindrical recess 120 is set higher than the total height (axial dimension) of the retainer 20 including the held O-ring 30. The retainer 20 is set in the cylindrical recess 120 of the first case 101 while holding the O-ring 30 and with the stopper 202 closed radially inward, and then the first case 101 and the second case 102 are screwed together. Therefore, the retainer 20 does not contact the mating surface of the second case 102 facing the O-ring 30, and it is possible to prevent the O-ring 30 from being rotated when the cases are screwed together.

[0037] Also, the dimension (depth) from the mating surface to the top surface of the stepped portion 130 of the cylindrical recess 120 is set lower than the total height (axial dimension) of the retainer 20 including the held O-ring 30. After the first case 101 and the second case 102 are screwed together and fastened, the protrusion 201 receives hydraulic pressure, and the retainer 20 moves toward the mating surface side of the second case 102 facing it. When it exceeds the stepped portion 130, the stopper 202 opens and is locked to the top surface of the stepped portion 130. Therefore, it is possible to seal the connection portion (connection point) between the first hydraulic circuit 111 and the second hydraulic circuit 112 with the O-ring 30.

[0038] As a result, when the mating surfaces of the first case 101 and the second case 102 are screwed together and fastened with a screw structure around the entire circumference, it is possible to prevent the rotation of the sealing member such as the O-ring 30, and thus it is possible to prevent the sealing performance of the in-case hydraulic circuit 110 communicated (connected) through the mating surface from being impaired.

[0039] According to this embodiment, the inner diameter of the stepped portion 130 is smaller than the outermost diameter (including the stopper 202) of the retainer 20 when the stopper 202 is open, and larger than the outermost diameter of the retainer 20 when the stopper 202 is closed. Therefore, by closing the stopper 202, the retainer 20 can be set on the bottom surface (inside the stepped portion 130) of the cylindrical recess 120 formed on the mating surface of the first case 101. Further, by opening the stopper 202, the retainer 20 can be locked (axial movement restricted) at the top surface of the stepped portion 130.

[0040] According to this embodiment, the inner diameter of the retainer 20 excluding the protrusion 201 is formed to be substantially the same as the diameters of the first hydraulic circuit 111 and the second hydraulic circuit 112. Therefore, the protrusion 201 protrudes (narrows the oil passage) radially inward of the first hydraulic circuit 111 and the second hydraulic circuit 112. Therefore, when hydraulic pressure is supplied to the first hydraulic circuit 111 and the second hydraulic circuit 112 (the in-case hydraulic circuit 110), a pressing force can be applied (generated) to the retainer 20 in the direction of the mating surface of the second case 102.

[0041] Further, according to this embodiment, an annular recess 203 for holding the O-ring 30 is formed on the top surface of the retainer 20, and the depth (axial dimension) of the annular recess 203 is set to be less than the diameter of the O-ring 30. Therefore, when the retainer 20 is locked to the stepped portion 130, the connection portion between the first hydraulic circuit 111 and the second hydraulic circuit 112 can be sealed with the O-ring 30.

[0042] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments and various modifications are possible. For example, in the above embodiment, the case where the present invention is applied to the transmission case 10 has been described as an example, but the present invention can also be applied to cases other than the transmission case 10. Further, in the above embodiment, the transmission case 10 was divided into two parts, but it may be divided into three parts (or more).

[0043] In addition, the material, shape, size, etc. of the retainer 20 described above are merely examples and are not limited to the above-described embodiments. For example, the shape (cross-sectional shape) of the protrusion (convex portion) 201 of the retainer 20 only needs to be able to move the retainer 20 in the axial direction under hydraulic pressure and is not limited to a triangle. Also, the shape and number of the stoppers 202 of the retainer 20 are not limited to the above-described embodiments.

[0044] Furthermore, in the above-described embodiment, the case internal hydraulic circuit 110 has been described by taking the case of one circuit as an example, but the number of case internal hydraulic circuits 110 may be plural.

Explanation of Reference Numerals

[0045] 1 Fastening structure 10 Transmission case (housing) 101 First case 1011 Female thread 102 Second case 1021 Male thread 110 Case internal hydraulic circuit 111 First hydraulic circuit 112 Second hydraulic circuit 120 Cylindrical recess 130 Step portion 20 Retainer 201 Protrusion (convex portion) 202 Stopper (claw portion) 203 Annular recess 30 O-ring (sealing member) 40 Liquid gasket

Claims

1. A first case in which a female thread is formed on the inner peripheral surface of the case that connects to the mating surface, and a first hydraulic circuit with an end exposed on the mating surface is formed inside; A second case in which a male thread that can be screwed with the female thread of the first case protrudes on the mating surface, and a second hydraulic circuit with an end exposed on the mating surface and communicable with the first hydraulic circuit is formed inside; A retainer formed in an annular shape, with a protruding portion protruding radially inward on the inner peripheral surface and a plurality of stoppers having radial flexibility formed on the outer peripheral surface; An annular seal member held by the retainer and disposed between the retainer and the mating surface of the case facing the retainer; Around the end of the first hydraulic circuit exposed on the mating surface of the first case or around the end of the second hydraulic circuit exposed on the mating surface of the second case, a cylindrical recess into which the retainer holding the seal member fits is formed, and along the inner surface connecting to the inner bottom surface of the cylindrical recess, a stepped portion protruding radially inward of the cylindrical recess is formed, which restricts the axial movement of the retainer when engaged with the stopper of the retainer; The dimension from the mating surface to the bottom surface of the cylindrical recess is set higher than the total height of the retainer including the held seal member, and the dimension from the mating surface to the top surface of the stepped portion of the cylindrical recess is set lower than the total height of the retainer including the held seal member; The retainer holds the seal member and is set in the cylindrical recess formed on the mating surface of the first case or the second case with the stopper closed radially inward. After the first case and the second case are screwed and fastened, the protruding portion receives hydraulic pressure and moves toward the mating surface side of the opposing case. When it exceeds the stepped portion, the stopper opens and is locked to the top surface of the stepped portion. A fastening structure characterized by this.

2. The inner diameter of the stepped portion is set smaller than the outermost diameter of the retainer when the stopper opens radially outward and larger than the outermost diameter of the retainer when the stopper closes radially inward. The fastening structure according to Claim 1, characterized by this.

3. The retainer has an inner diameter excluding the protrusion formed to be substantially the same as the diameters of the first hydraulic circuit and the second hydraulic circuit, and an annular recess for holding the seal member is formed on the top surface. The fastening structure according to claim 2, characterized in that.

4. The first case and the second case are cases of a transmission, The fastening structure according to claim 3, characterized in that the seal member is an O-ring.

5. A fastening method using the fastening structure according to claim 1, A first step of setting the retainer holding the seal member in a state where the stopper is closed radially inward in the cylindrical recess formed on the mating surface of the first case or the second case; Then, a second step of screwing and fastening the first case and the second case; After fastening the first case and the second case, hydraulic pressure is supplied to the first hydraulic circuit and the second hydraulic circuit, hydraulic pressure is applied to the protrusion of the retainer to move the retainer to the mating surface side of the opposing case, and when the step portion is exceeded, the stopper is opened and locked to the top surface of the step portion. A fastening method characterized by comprising a third step.

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