JP7258436B2 - Shaft fixing structure - Google Patents

Description

The present invention relates to a structure for fixing a shaft held by a holding member to the holding member.

For example, in a vehicle equipped with an automatic transmission, power from a driving source such as an engine is transmitted to the automatic transmission via a torque converter.

A torque converter has a configuration in which a stator is arranged between a pump impeller and a turbine runner. When the power from the drive source rotates the pump impeller, oil flows from the pump impeller toward the turbine runner. This oil flow is received by the blades of the turbine runner, causing the turbine runner to rotate. By transmitting the rotation of the turbine runner to the automatic transmission, transmission of power to the automatic transmission by the torque converter is achieved. Due to the provision of the stator, the flow of oil returned from the turbine runner to the pump impeller is deflected in a direction that accelerates the rotation of the pump impeller, thereby amplifying the rotational torque of the pump impeller.

The stator is held by a one-way bearing on the stator shaft. The stator shaft is then fixed to, for example, a unit case housing a torque converter and an automatic transmission. As a method for fixedly holding the stator shaft in the unit case, there is known a method in which knurling is formed on the outer peripheral surface of the stator shaft and the knurled portion is press-fitted into the unit case.

JP 2008-208892 A

In this method, the torsional load (rotational load) input to the stator shaft can be supported. However, an axial load is generated on the stator shaft due to whirling load and hydraulic pressure due to the stator receiving oil flow. Therefore, the stator shaft may be displaced in the direction opposite to the press-fitting direction into the unit case.

SUMMARY OF THE INVENTION An object of the present invention is to provide a shaft fixing structure capable of suppressing displacement of a shaft press-fitted into a holding member in a direction opposite to the press-fitting direction.

In order to achieve the above object, a shaft fixing structure according to one aspect of the present invention is a structure for fixing a shaft held by a holding member to the holding member, wherein the holding member includes a cylinder into which the shaft is press-fitted. A surface and a cylindrical through-hole opened in the cylindrical surface are formed, and a tapping screw is screwed into the through-hole, and the tip of the tapping screw screwed into the through-hole is formed on the peripheral surface of the shaft. grooves are formed to receive the

In this structure, the holding member is formed with a cylindrical surface and a through hole. A shaft is press-fitted into the cylindrical surface. A tapping screw is screwed into the through hole. The through hole is open on the cylindrical surface, and the tapping screw protrudes from the cylindrical surface and has its tip end received in a groove formed on the peripheral surface of the shaft. Therefore, when an axial load is applied to the shaft in the direction opposite to the press-fitting direction, the tapping screw serves as a stopper, and the shaft can be prevented from slipping in the direction opposite to the press-fitting direction.

In addition, since the tapping screw is screwed into the through hole, a female thread is formed on the inner peripheral surface of the through hole, and springback after the formation of the female thread eliminates the gap between the female thread and the tapping screw, thereby providing loosening resistance. Therefore, it is not necessary to apply an adhesive to prevent loosening, and the material cost and the number of steps can be reduced.

A shaft fixing structure according to another aspect of the present invention is a structure for fixing a shaft held by a holding member to the holding member. The through hole extends in a direction inclined with respect to the direction of the center line of the cylindrical surface, and a screw having a flat tip surface is screwed into the through hole, A groove is formed around the shaft for receiving the tip of a screw threaded into the through hole, and the groove has an abutment surface orthogonal to the center line of the through hole.

In this structure, the holding member is formed with a cylindrical surface and a through hole. A shaft is press-fitted into the cylindrical surface. A screw is screwed into the through hole. The through-hole is open on the cylindrical surface, and the screw protrudes from the cylindrical surface and its tip is received in a groove formed on the peripheral surface of the shaft. Therefore, when an axial load is applied to the shaft in the direction opposite to the press-fitting direction, the screw serves as a stopper, and the shaft can be prevented from being displaced in the direction opposite to the press-fitting direction.

Moreover, since the through hole is inclined with respect to the direction of the center line of the cylindrical surface, and the groove has an abutment surface perpendicular to the center line of the through hole, the screw screwed into the through hole is attached to the abutment surface. can be brought into contact with the tip surface of the Since the backlash between the screw and the shaft is eliminated by abutting the tip surface of the screw against the abutment surface of the groove, it is possible to further suppress the shift of the shaft in the direction opposite to the press-fitting direction.

In any shaft fixing structure, it is preferable that knurling is formed on the outer peripheral surface of the shaft and the knurled portion is press-fitted into the cylindrical surface of the holding member. As a result, when a twisting load is applied to the shaft, the twisting load can be received by the press-fit portion of the knurl. Therefore, it is possible to further suppress the shift of the shaft in the twisting direction.

According to the present invention, it is possible to prevent the shaft press-fitted into the holding member from shifting in the direction opposite to the press-fitting direction.

1 is a perspective view showing part of a transmission unit to which a shaft fixing structure according to an embodiment of the invention is applied; FIG. FIG. 3 is a view of part of the transmission unit viewed from one side in the direction of the rotation axis of the torque converter; 3 is a cross-sectional view of the stator shaft and the unit case along the cutting plane line AA shown in FIG. 2; FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Below, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<Shaft fixing structure>
FIG. 1 is a perspective view showing part of a transmission unit 1 to which a shaft fixing structure according to one embodiment of the invention is applied.

The transmission unit 1 is a unit that accommodates a torque converter and an automatic transmission in a unit case 2 and that shifts power from a drive source such as an engine. The torque converter has a structure in which a stator is arranged between a pump impeller and a turbine runner, and the stator is held on a stator shaft 3 by a one-way bearing. A stator shaft 3 is fixed to the unit case 2 .

FIG. 2 is a view of part of the transmission unit 1 as viewed from one side in the direction of the rotational axis of the torque converter. FIG. 3 is a cross-sectional view of the unit case 2 and the stator shaft 3 taken along line AA shown in FIG.

A thick portion 11 is formed in the unit case 2 by partially increasing the thickness. A shaft insertion hole 12 is formed through the thick portion 11 in the rotational axis direction of the torque converter (hereinafter simply referred to as the "rotational axis direction"). The shaft insertion hole 12 has a cylindrical surface 13 whose centerline extends in the rotation axis direction. Moreover, the thick portion 11 is formed in a truncated cone shape in which an end portion 14 on one side in the rotation axis direction is reduced in diameter toward the one side.

A cylindrical through hole 15 is formed in the unit case 2 . The through hole 15 extends obliquely with respect to the rotation axis direction. The through hole 15 penetrates between the cylindrical surface 13 and the circumferential surface of the truncated cone-shaped end portion 14 , and both ends of the through hole 15 are open at the cylindrical surface 13 and the circumferential surface of the end portion 14 .

The stator shaft 3 is formed in a substantially cylindrical shape, and one end thereof is formed as a press-fit portion 21 having an outer diameter slightly larger than the diameter of the shaft insertion hole 12 of the unit case 2 . The stator shaft 3 extends from one side of the shaft insertion hole 12 in the rotation axis direction, that is, the side where the end portion 14 of the unit case 2 is formed, with the end opposite to the press-fit portion 21 facing the shaft insertion hole 12 . , is inserted through the shaft insertion hole 12 . Then, the press-fitting portion 21 is press-fitted into the shaft insertion hole 12 .

On the peripheral surface of the press-fitting portion 21, at the end on the upstream side in the press-fitting direction with respect to the shaft insertion hole 12 (one side in the direction of the rotation axis when the press-fitting portion 21 is press-fitted into the shaft insertion hole 12), for example, a stator shaft A knurl 22 consisting of a large number of ridges extending in the direction of the center line of 3 is formed. Therefore, when the press-fit portion 21 is press-fitted into the shaft insertion hole 12 , the cylindrical surface 13 of the shaft insertion hole 12 is knurled by the knurls 22 .

A groove 23 is formed in the peripheral surface of the press-fit portion 21 . The groove 23 has a substantially V-shaped cross section with a contact surface 24 . The contact surface 24 is formed on a plane perpendicular to the center line of the through-hole 15 when the press-fitting portion 21 is press-fitted into the shaft insertion hole 12 .

The rotational position of the stator shaft 3 is adjusted so that the groove 23 overlaps the through hole 15 when the press fitting portion 21 is press fitted into the shaft insertion hole 12 . When the press-fitting portion 21 is press-fitted into the shaft insertion hole 12 until the groove 23 overlaps the through-hole 15 , the screw 25 is screwed into the through-hole 15 . The screw 25 is a self-tapping screw that does not have a screw head. Both ends of the screw 25 are formed substantially flat, and a square hole (for example, a hexagonal hole or a hexagonal star hole) for fitting a tool is formed in the end face on one side. The screw 25 is screwed into the through hole 15 with the end face opposite to the end face where the square hole is formed facing the inside of the through hole 15 . At this time, the female thread is plastically formed on the inner peripheral surface of the through hole 15, and after the self-tapping, the gap between the female thread and the thread of the screw 25 disappears due to springback. The screw 25 protrudes from the cylindrical surface 13 of the shaft insertion hole 12 and is screwed until the tip end surface contacts the contact surface 24 of the groove 23 .

<Effect>
As described above, the cylindrical surface 13 and the through hole 15 are formed by the shaft insertion hole 12 in the unit case 2 . A press-fitting portion 21 of the stator shaft 3 is press-fitted into the cylindrical surface 13 . A screw 25 is screwed into the through hole 15 . The through-hole 15 is open at the cylindrical surface 13 , and the screw 25 protrudes from the cylindrical surface 13 and has its tip received in a groove 23 formed on the peripheral surface of the press-fit portion 21 . Therefore, when a load in the direction opposite to the press-fitting direction is applied to the press-fitting portion 21 , the screw 25 serves as a stopper to prevent the press-fitting portion 21 from shifting in the direction opposite to the press-fitting direction.

Moreover, since the through hole 15 is inclined with respect to the rotation axis direction (the direction of the center line of the cylindrical surface 13) and the groove 23 has the contact surface 24 orthogonal to the center line of the through hole 15, A tip surface of a screw 25 screwed into the through hole 15 can be brought into contact with the contact surface 24 . Since the tip surface of the screw 25 abuts against the contact surface 24 of the groove 23, the backlash between the screw 25 and the press-fit portion 21 is eliminated, thereby further suppressing the displacement of the press-fit portion 21 in the direction opposite to the press-fit direction. can.

Further, knurls 22 are formed on the outer peripheral surface of the press-fitting portion 21 , and the portion where the knurling 22 is formed is press-fitted into the shaft insertion hole 12 of the unit case 2 . As a result, when a twisting load is applied to the press-fit portion 21, the press-fit portion of the knurl 22 can bear the twisting load. Therefore, it is possible to further suppress the displacement of the press-fit portion 21 in the twisting direction.

Further, since the screw 25 is a tapping screw and is screwed into the through hole 15, an internal thread is formed on the inner peripheral surface of the through hole 15, and springback after the formation of the internal thread causes the internal thread and the screw 25 to be connected. There is no gap and loosening resistance is generated. Therefore, it is not necessary to apply an adhesive to the screw 25 to prevent loosening, and the material cost and the number of processes required for applying the adhesive can be reduced.

Moreover, since the screw 25 is a countersunk screw, it is not necessary to form a bearing surface on which the screw head is seated on the unit case 2, thereby reducing the cost and the number of steps required for forming the bearing surface.

<Modification>
Although one embodiment of the present invention has been described above, the present invention can also be implemented in other forms.

For example, screw 25 may be a tapping screw with a screw head or a non-self-tapping screw. Also, the screw 25 may be a general screw that has a screw head and does not self-tap. If the screw 25 is not a tapping screw (a screw that does not self-tap), the screw 25 may be coated with an adhesive to prevent loosening.

The present invention is applied to a structure for fixing the stator shaft 3 to the unit case 2 as an example, but the present invention is widely applicable to a structure for fixing a shaft held by a holding member to the holding member. be able to. However, the stator shaft 3 is subjected to an axial load due to whirling load and hydraulic pressure caused by the stator receiving oil flow. In the case of

In addition, various design changes can be made to the above configuration within the scope of the matters described in the claims.

2: Unit case (holding member)
3: Stator shaft (shaft)
13: Cylindrical surface 15: Through hole 23: Groove 24: Contact surface 25: Screw (tapping screw)

Claims (2)

A structure for fixing a shaft held by a holding member to the holding member,
The holding member is formed with a cylindrical surface into which the shaft is press-fitted and a cylindrical through-hole opened at the cylindrical surface,
A tapping screw is screwed into the through hole,
A groove for receiving the tip of the tapping screw screwed into the through hole and a knurl are formed on the peripheral surface of the shaft ,
The shaft fixing structure , wherein the knurled portion of the shaft is press-fitted into the cylindrical surface . A structure for fixing a shaft held by a holding member to the holding member,
The holding member is formed with a cylindrical surface into which the shaft is press-fitted and a cylindrical through-hole opened at the cylindrical surface,
The through hole extends in a direction inclined with respect to the center line of the cylindrical surface,
A screw having a flat tip surface is screwed into the through hole,
A groove for receiving a tip of the screw screwed into the through hole and a knurl are formed on the peripheral surface of the shaft,
the groove has a contact surface perpendicular to the direction of the center line of the through hole ,
The shaft fixing structure , wherein the knurled portion of the shaft is press-fitted into the cylindrical surface .

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