JP2013185662A - Fastening structure of ring gear and fastening method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability of an integrated product formed by fastening a ring gear to a fastened member.SOLUTION: Engagement torque T is applied to a helical tooth 14f of a ring gear 14. A resultant engagement thrust reaction force Tacts on screw threads of screw parts 16 formed on contact faces 12a, 14a between a differential case 12 as the fastened member and the ring gear 14. A horizontal direction of a spiral of the screw part 16 is aligned with a horizontal direction of the helical tooth 14f of the ring gear 14. The engagement torque T generating the engagement thrust reaction force Tsimultaneously generates an axial force Fin a direction opposite the engagement thrust reaction force Tto cancel the engagement thrust reaction force T, in the screw part 16 formed on the contact faces 12a, 14a between the differential case 12 and the ring gear 14.

Description

  The present invention relates to a ring gear fastening structure and a fastening method.

Conventionally, a method of constructing an integral part by combining a ring gear with a separate member to be fastened has been widely used. As an example, a differential differential case assembly that is a component of an automobile drive system is used. Attached structure is mentioned. A differential case assembly 10 shown in FIG. 2A is configured by fastening a differential case (differential case) 12 and a ring gear 14. As shown in FIG. 2B, the cylindrical outer peripheral surface 12a of the differential case 12 and the inner peripheral surface 14a of the ring gear 14 are mutually press-fitting surfaces, and the ring gear 14 is pressed into the differential case 12 in the axial direction. Thus, both are integrated. In this state, a reaction force P in the radial direction due to the press-fitting allowance is generated on the outer peripheral surface 12a of the differential case 12 and the inner peripheral surface 14a of the ring gear 14, and the axial friction force F = μP thereby causes both shafts The direction position is fixed.

Further, in order to more reliably position the ring gear 14 in the axial direction with respect to the differential case 12, a stopper portion 12b that protrudes annularly in the radial direction is formed on the base end side (right side in FIG. 2) of the differential case 12 in the axial direction. The one side surface 14b of the ring gear 14 is in contact with the stopper portion 12b. Further, the tip end portion in the axial direction of the differential case 12 (the left end portion in FIG. 2) is caulked to constitute a caulking portion 12c, which is bitten into a notch 14d formed on the other side surface 14c of the ring gear 14 (for example, patent Reference 1). As shown in FIG. 3, the notch 14d is a V-shaped concave portion formed at equal intervals in the circumferential direction at the corner where the inner peripheral surface 14a of the ring gear 14 and the other side surface 14c intersect. is there. Therefore, the ring gear 14 press-fitted into the differential case 12 has its one side surface 14b regulated by the stopper portion 12b of the differential case 12, and the other side surface 14c regulated by the caulking portion 12c of the differential case 12, so that the axial and circumferential positions thereof are regulated. 12 and the ring gear 14 are positioned relative to each other.

European Patent Application No. 0647789

However, an axial force may be applied to the differential case 12 and the ring gear 14 by the force acting on the differential case assembly 10 during operation of the automobile. In particular, when the ring gear 14 is a helical gear, the torque T is applied to the ring gear 14 as shown in FIG. 2 (c), so that not only the meshing radial reaction force _Tr but also the meshing. A large thrust reaction force T _s is generated. At this time, the axial frictional force F = μP is generated on the outer peripheral surface 12a of the differential case 12 and the inner peripheral surface 14a of the ring gear 14 as described above. Here, as shown in FIG. 2C, when the torque T is a light load _TL , the frictional force F exceeds the meshing thrust reaction force Ts, and the axial direction between the differential case 12 and the ring gear 14 increases. Misalignment X does not occur. However, the torque T is, when a heavy load T _H as shown in FIG. 2 (d), and thus exceeds the frictional force F meshing thrust counterforces Ts occurs at the contact surfaces 12a, 14a. The axial displacement X between the ring gear 14 and the differential case 12 due to the thrust reaction force due to the minute gap between the ring gear and the differential case due to the inevitable spring back of the caulking portion 12c of the differential case 12 (X> 0) is generated. Further, when the difference between the differential case 12 and the ring gear 14 is repeated, the contact surfaces 12a and 14a between the ring gear 12 and the differential case 14 are worn, reducing the press-fitting allowance of both, reducing the surface pressure of the contact surfaces 12a and 14a, The frictional force on the contact surfaces 12a and 14a is reduced. Furthermore, by the reaction force F ₂ in the axial direction caused between the notches 14d of the crimping portion 12c and the ring gear 14 of the differential case 12, there is a risk of causing deformation to caulking portion 12c. Further, when the torque T acting in the opposite direction to the FIG. 2 (b) (c), the thrust counterforces T _s also acts in the axial direction of the opposite, first side surface of the stopper portion 12b and the ring gear 14 of the differential case 12 14b reaction force F ₂ in the axial direction is generated between the, in the stopper portion 12b, which may cause a deformation.

  The present invention has been made in view of the above problems, and the purpose of the present invention is to prevent a situation in which a force acts on an integrated product obtained by fastening a ring gear and a member to be fastened, causing a shift between the two. The purpose is to reliably prevent and further improve the reliability of this integrated product.

(Aspect of the Invention)
The following aspects of the present invention exemplify the configuration of the present invention, and will be described separately for easy understanding of various configurations of the present invention. Each section does not limit the technical scope of the present invention, and some of the components of each section are replaced, deleted, or further while referring to the best mode for carrying out the invention. Those to which the above components are added can also be included in the technical scope of the present invention.

(1) A ring gear including a helical ring and a fastened member that fastens the ring gear in the axial direction thereof, wherein a thread portion is formed on a contact surface between the ring gear and the fastened member, and the screw A ring gear fastening structure in which the left-right direction of the spiral of the part and the left-right direction of the helical torsion of the ring gear are formed in the same direction (Claim 1).
In the fastening structure of the ring gear described in this section, a meshing torque is applied to the ring gear helical, and a meshing thrust reaction force generated thereby is generated by the screw portion formed on the contact surface between the ring gear and the fastened member. Acts on the thread. Here, since the left and right direction of the spiral of the screw portion and the left and right direction of the helical torsion of the ring gear are formed in the same direction, the meshing torque that generates this meshing thrust reaction force is the same as that of the ring gear. In the threaded portion formed on the contact surface with the fastened member, an axial force in a direction opposite to the meshing thrust reaction force is also generated at the same time, thereby canceling the meshing thrust reaction force.

For example, consider a case where the helical twist direction of the ring gear is the “right” direction and the helical twist direction of the threaded portion is the “right” direction, that is, the “right screw”. At this time, the meshing torque that generates the meshing thrust reaction force in the direction of dropping the ring gear from the engaged member is simultaneously applied to the engaged member at the screw portion formed on the contact surface between the ring gear and the fastened member. An axial force in a direction that deepens the screwed state of the ring gear is also generated.
In addition, since the helical direction of the ring gear and the helical direction of the threaded portion have the above relationship, the meshing torque applied to the ring gear can be either positive or negative. Also, an axial force in a direction that cancels the meshing thrust reaction force is generated.

(2) In the above item (1), at least one of the pitch, the thread shape, and the surface property of the screw part is determined according to the helical angle of the ring gear. Fastening structure (claim 2).
In the fastening structure of the ring gear described in this section, at least one of the pitch of the thread portion, the thread shape, and the surface property of the thread portion is determined according to the helical angle of the ring gear. As a result, a meshing torque is applied to the ring gear helical, and the meshing thrust reaction force generated thereby balances the axial force of the thread formed on the contact surface of the ring gear and the fastened member. Become.

(3) A ring gear fastening structure according to the above items (1) and (2), wherein the fastened member is a differential case (claim 3).
The fastening structure of the ring gear described in this section is a fastening structure composed of a ring gear and a differential case, and exhibits the predetermined action described in the above items (1) and (2).

  (4) A method of fastening a ring gear provided with a helical member and a fastened member that fastens the ring gear in its axial direction, wherein a spiral left-right direction is formed on a contact surface between the ring gear and the fastened member. A ring gear fastening method in which a threaded portion in the same direction as the helical torsion of the ring gear is formed, and the ring gear and the fastened member are fastened by the threaded portion (Claim 4).

In the ring gear fastening method described in this section, a meshing torque is applied to the ring gear helical, and the meshing thrust reaction force generated thereby is applied to the screw portion formed on the contact surface between the ring gear and the member to be fastened. It acts on the thread. Further, by forming the left and right direction of the spiral of the screw portion in the same direction as the left and right direction of the helical torsion of the ring gear, the meshing torque that generates the meshing thrust reaction force causes the ring gear and the member to be fastened. In the screw portion formed on the contact surface, an axial force in a direction opposite to the meshing thrust reaction force is also generated at the same time to cancel the meshing thrust reaction force.
Also, by engaging the ring gear so that the helical direction of the helical ring and the helical direction of the threaded portion are in the above relationship, the meshing torque applied to the helical ring gear can be adjusted in the positive and negative directions. In either case, an axial force in a direction that cancels the meshing thrust reaction force is generated.

(5) In the above item (4), at least one of the pitch of the threaded portion, the thread shape, and the surface property of the threaded portion is determined according to the helical torsion angle of the ring gear. A method for fastening a ring gear (claim 5).
The ring gear fastening method described in this section determines at least one of the pitch of the threaded portion, the thread shape, and the surface property of the threaded portion according to the helical angle of the ring gear. As a result, a meshing torque is applied to the ring gear helical, and the meshing thrust reaction force generated thereby balances the axial force of the thread formed on the contact surface of the ring gear and the fastened member. is there.

(6) In the above items (4) and (5), a threaded portion is formed in advance on both contact surfaces of the ring gear and the member to be fastened, and the ring gear and the member to be fastened are screwed into the ring gear. And a method for fastening a ring gear for fastening the member to be fastened (Claim 6).
In the method for fastening the ring gear described in this section, before the ring gear and the member to be fastened are fastened, screw parts are formed on both contact surfaces in advance so that both screw parts are screwed together. The screw is fastened. A meshing torque is applied to the helical gear of the ring gear, and the meshing thrust reaction force generated thereby acts on the thread of the thread portion formed on the contact surface between the ring gear and the fastened member.
(7) In the above items (4) and (5), the ring gear is formed by screwing the ring gear and the member to be fastened in advance on one of the contact surfaces of the ring gear and the member to be fastened. And a method for fastening a ring gear for fastening the member to be fastened (Claim 6).
In the ring gear fastening method described in this section, before the ring gear and the member to be fastened are fastened, a threaded portion is formed in advance on one contact surface, and both are screwed into a threaded portion on the other contact surface. Is transferred and screwed and fastened. A meshing torque is applied to the helical gear of the ring gear, and the meshing thrust reaction force generated thereby acts on the thread of the thread portion formed on the contact surface between the ring gear and the fastened member.

(8) A method for fastening a ring gear according to (4) to (7) above, wherein the member to be fastened is a differential case (claim 7).
The ring gear fastening method described in this section provides the predetermined operation described in the above items (4) to (7) in the ring gear and differential case fastening method.

  Since the present invention is configured as described above, the force acts on the integrated product formed by fastening the annular member and the member to be fastened, and the situation in which the two are displaced more reliably can be prevented. Further improvement can be achieved.

FIG. 1 shows a differential case assembly according to an embodiment of the present invention, in which (a) shows meshing when torque is applied to the differential case assembly when the ring gear is twisted in the right direction and the threaded portion is a right-hand thread. A side view schematically showing the reaction force, (b) is a simplified view of the differential case assembly of (a), a schematic diagram showing the axial force generated in the screw portion when torque is applied to the ring gear, (C) is a side view schematically showing the meshing reaction force when torque is applied to the differential case assembly when the ring gear is twisted in the left direction and the threaded portion is a left-hand thread. The differential case assembly is further simplified and is a schematic diagram showing the axial force generated in the threaded portion when torque is applied to the ring gear, (e) is the differential case of (a). Sectional view showing the relationship between the meshing reaction force and the axial force when positive torque is applied to the assembly, (f) is the meshing when negative torque is applied to the differential case assembly of (a). It is principal part sectional drawing which shows the relationship between high reaction force and axial force. (A) is a schematic diagram which shows a differential case assembly as an example of the fastening structure of the conventional annular member, (b) at the time of no load, (c) at the time of light load, (d) at the time of heavy load, It is a fragmentary sectional view explaining the relationship of the force which arises between an annular member and a to-be-fastened member. FIG. 3 is a partial view of the ring gear shown in FIG. 2, (a) is a perspective view showing a notch, (b) is a front view of the notch, (c) is a cross-sectional view taken along line AA in (b), (d ) Is a sectional view taken along line BB in FIG.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. In the following description, parts that are the same as or correspond to those in the prior art are assigned the same reference numerals, and detailed descriptions thereof are omitted.
FIG. 1 shows an example in which the annular member fastening structure according to the first embodiment of the present invention is adopted in a differential case assembly 10. Also in this example, the cylindrical outer peripheral surface 12a of the differential case 12 and the inner peripheral surface 14a of the ring gear 14 come into contact with each other as in the example of FIG.

Here, a helical gear 14f is formed in the ring gear 14 of FIG. Moreover, in the embodiment of the present invention, the threaded portion 16 is formed on the contact surface 12 a of the differential case 12 and the contact surface 14 a of the ring gear 14. Moreover, the left-right direction of the spiral of the screw portion 16 is formed in the same direction as the left-right direction of the torsion of the helical 14 f of the ring gear 14.
Specifically, in the example shown in FIGS. 1A and 1B, since the twist direction of the helical 14f is a so-called right handling gear 14R in the “right” direction, the helical twist of the screw portion 16 The direction is also the “right” direction, that is, the right screw 16R. On the other hand, in the example shown in FIGS. 1C and 1D, since the twist direction of the helical 14f is a so-called left handling gear 14L in the “left” direction, the twist direction of the spiral of the screw portion 16 is also In the “left” direction, that is, the left screw 16L.

Furthermore, in the embodiment of the present invention, at least one of the pitch of the thread portion 16, the thread shape, and the surface property of the thread portion 16 is determined according to the helix angle of the helical 14 f of the ring gear 14. Yes.
These adjustment items, as described later, the meshing torque T is applied to 14f Invite to the ring gear 14 of the contact surface 12a of it and thrust counterforces T _s meshing caused by the differential case 12 and the ring gear 14, the axial force F _a to be generated in the threaded portion 16 formed in 14a, is for setting to balance the axial direction. Further, when the differential case 12 and the ring gear 14 are fastened, the frictional force generated in the screw portion 16 may be adjusted by applying a friction stabilizer to at least one of the contact surfaces 12a and 14a.

Now, according to the embodiment of the present invention configured as described above, the following operational effects can be obtained.
That is, as shown in FIGS. 1 (f) and 1 (g), the meshing torque T is applied to the helical 14 f of the ring gear 14, and the meshing thrust reaction force T _s generated thereby is the differential case that is the fastened member 12 acts on the thread of the thread portion 16 formed on the contact surfaces 12a, 14a between the ring gear 14 and the ring gear 14. Here, the left-right direction of the spiral of the screw portion 16 and the left-right direction of the torsion of the helical gear 14f of the ring gear 14 are formed in the same direction. Therefore, meshing torque T to generate the meshing thrust counterforces T _s, the contact surface 12a of the differential case 12 and the ring gear 14, the threaded portion 16 formed on the 14a, meshing thrust counterforces T _s and the counter The axial force F _a in the direction to be generated is generated at the same time, and the meshing thrust reaction force T _s can be canceled by the axial force F _a .

For example, let us consider a case where the twist direction of the helical 14f is the “right” direction as in the light handling gear 14R shown in FIGS. At this time, the twist direction of the spiral of the screw portion 16 is the “right” direction, that is, the right screw 16R and the direction in which the ring gear 14 is dropped from the differential case 12 (the left direction in FIGS. 1A and 1B). meshing torque T produce meshing thrust counterforces T _s at the same time, the threaded portion 16, (right direction in FIG. 1 (a) (b)) direction to further deepen the screwed state of the ring gear relative to the engaged member of to generate axial force F _a, becomes offset the meshing thrust counterforces T _s.

On the other hand, as in the left handling gear 14L shown in FIGS. 1C and 1D, the twist direction of the helical 14f is the “left” direction and the twist direction of the spiral of the screw portion 16 is the “left” direction. That is, consider the case of the left-hand thread 16L. In this case, meshing meshing torque T produce thrust counterforces T _s (right direction in FIG. 1 (c) (d)) direction to further deepen the screwed state of the ring gear 14 relative to the differential case 12, at the same time, threaded section in 16, it is assumed that offset the axial force F _a is generated, meshing thrust counterforces T _s in a direction to shed the ring gear 14 from the differential case 12 (the left direction in FIG. 1 (c) (d)) .

In addition, since the twist direction of the helical 14f of the ring gear 14 and the twist direction of the spiral of the threaded portion 16 have the above relationship, the ring gear 14 has the following relationship as shown in FIGS. meshing torque T applied to Suva 14f is be either positive or negative direction (T ^{+, T -),} and those for generating the axial force F _a in a direction to cancel the meshing thrust counterforces T _s Become.
That is, as shown in FIG. 1 (f), to 14f when to ring gear 14 of, when a positive torque T ⁺ is assigned (during forward driving) is meshing caused by positive torque T ⁺ reaction force T _s ⁺ And the axial force F _a ⁺ generated in the screw portion 16 are in a direction to cancel each other, and the axial reaction force F ₂ generated between the stopper portion 12b of the differential case and the one side surface 14b of the ring gear 14 is reduced. It becomes possible. On the other hand, as shown in FIG. 1 (g), to 14f when to ring gear 14 of the negative torque T ^- when is attached (during reverse drive, and when MT vehicle engine braking, regenerative braking of the hybrid vehicle or the like In operation, etc., the meshing reaction force T _s ⁻ generated by the negative torque T ⁻ and the axial force F _a ⁻ generated in the screw portion 16 are in a direction to cancel each other, and the caulking portion 12c of the differential case 12 and the ring gear 14 it is possible to reduce the reaction force F ₂ in the axial direction caused between the notches 14d.

In the embodiment of the present invention, at least one of the pitch of the thread portion 16, the thread shape, and the surface property of the thread portion 16 is determined according to the helix angle of the helical 14 f of the ring gear 14. it allows the ring gear 14 of the meshing torque T to 14f if you grant, it the thrust counterforces T _s meshing caused by, the axial force F _a that occurs at the screw portion 16, can be balanced with Become.

  If the screw part 16 is formed in advance on both contact surfaces 12a and 14a before the differential case 12 and the ring gear 14 are fastened, the screw parts 16 are screwed together so that both the screw parts 16 are screwed together. Fastened to facilitate the coupling operation of the differential case 12 and the ring gear 14.

Further, for example, the threaded portion 16 is formed only on the contact surface 14a of the ring gear 14, and the contact surface 12a of the differential case 12 remains in a lathe state (that is, the threaded portion is not formed). The contact surface 14a of the ring gear 14 may be screwed into the surface 12a so as to be fastened by so-called serration press-fitting. In this case, by screwing both, the threaded portion 16 of the ring gear 14 is transferred to the contact surface 12a of the differential case 12, and both the contact surfaces 12a and 14a are in a press-fit state, so that a stronger fastening state can be obtained. It becomes. Further, the same operation and effect can be obtained by forming the threaded portion 16 only on the contact surface 12a of the differential case 12 and leaving the contact surface 14a of the ring gear 14 in a lathe state. .

As described above, in the embodiment of the present invention, the differential case assembly 10 is taken as an example as an example of a fastening structure including a ring gear and a member to be fastened to press-fit an annular member. However, the application target of the present invention is not limited to this. For example, even when the annular member having the inner teeth is press-fitted into the inner surface of the cylindrical member to be fastened, the same effect is obtained. Will be understood.

10: differential case assembly, 12: differential case, 12a: outer peripheral surface (contact surface), 12b: stopper portion, 12c: caulking portion, 14: ring gear, 14L: left handling gear, 14R: right handling gear, 14a: inner peripheral surface ( Contact surface), 14b: one side surface, 14c: the other side surface, 14d: notch, 14f: helical, 16: threaded portion, 16L: left-handed screw, 16R: right-handed screw, F: frictional force, Fa, Fa ⁺ , Fa ⁻ : axial force, F ₂ : axial reaction force, P: radial reaction force, T: meshing torque, T ⁺ : positive torque, T ⁻ : negative torque, T _r : meshing radial reaction force , T _s , T _s ⁺ , T _s ⁻ : meshing thrust reaction force, μ: friction coefficient

Claims (7)

A ring gear provided with a helix and a fastened member that fastens the ring gear in its axial direction;
A screw part is formed on the contact surface between the ring gear and the member to be fastened, and the left and right direction of the spiral of the screw part and the left and right direction of the helical torsion of the ring gear are formed in the same direction. A ring gear fastening structure characterized by that. 2. The ring gear according to claim 1, wherein at least one of a pitch, a thread shape, and a surface property of the thread portion is determined according to a helical angle of the ring gear. Fastening structure. The ring gear fastening structure according to claim 1, wherein the fastened member is a differential case. A fastening method of a ring gear provided with a helical and a fastened member that fastens the ring gear in its axial direction,
On the contact surface between the ring gear and the member to be fastened, a screw portion is formed in which the left-right direction of the spiral is the same direction as the left-right direction of the helical torsion of the ring gear. A ring gear fastening method comprising fastening a fastening member. The fastening of the ring gear according to claim 4, wherein at least one of the pitch, the thread shape, and the surface property of the thread portion of the thread portion is determined according to a helical twist angle of the ring gear. Method. A thread portion is formed in advance on one or both of the contact surfaces of the ring gear and the fastened member, and the ring gear and the fastened member are screwed to fasten the ring gear and the fastened member. 6. The ring gear fastening method according to claim 4, wherein the ring gear is fastened. The ring gear fastening method according to any one of claims 4 to 6, wherein the fastened member is a differential case.

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