CN217814888U

CN217814888U - Pinion shaft structure

Info

Publication number: CN217814888U
Application number: CN202220600396.3U
Authority: CN
Inventors: 山内清茂
Original assignee: NTN Corp
Current assignee: NTN Corp
Priority date: 2021-03-24
Filing date: 2022-03-18
Publication date: 2022-11-15
Anticipated expiration: 2032-03-18
Also published as: JP2022148022A

Abstract

Provided is a pinion shaft structure having a stopper pin which has higher dimensional accuracy than conventional ones and is less likely to come off a center hole. The pinion shaft structure comprises a pinion shaft, a vertical hole formed in the pinion shaft and extending from one end of the pinion shaft to the other end, an inlet hole and an outlet hole formed in the pinion shaft and connected to the vertical hole, and a stopper pin (26) pressed into one end of the vertical hole to close the vertical hole, wherein the stopper pin (26) is a tapered surface (28) which is solid, made of an alloy having a copper content of 55 mass% or more and a zinc content of 45 mass% or less, has a surface hardness of 80HV or more and 200HV or less in terms of Vickers hardness, and has a predetermined slope in the outer peripheries of both end portions with respect to the axial center of the stopper pin (26), wherein the predetermined slope is a slope included in a range of 10 DEG or more and 30 DEG or less.

Description

Pinion shaft structure

Technical Field

The present invention relates to a pinion shaft that rotatably supports a pinion.

Background

In a planetary gear mechanism of a transmission of an automobile, the following configurations are widely known: a pinion shaft is inserted into a center hole of the planetary gear (pinion), and the pinion shaft rotatably supports the planetary gear via a rolling bearing. In order to supply the lubricating oil to the rolling bearing on the outer periphery of the pinion shaft, a path (a center hole extending in the axial direction) through which the lubricating oil flows is provided in the axial center of the pinion shaft. The pinion shaft has a stopper pin for closing an end opening of the center hole, which is unavoidable in terms of machining.

As such a pinion shaft, as shown in, for example, the drawings of japanese utility model registration No. 2604564 (patent document 1), there is known a structure in which a center hole through which lubricating oil flows is bored in the shaft center of a shaft and an end of the center hole is closed by a stopper pin. Conventional retaining pins have a U-shaped or substantially U-shaped cross-section

The shape of the shaft is substantially bowl-shaped and is press-fitted into the center hole of the pinion shaft. The stopper pin is generally press-formed into a substantially bowl shape from a flat plate of low-carbon steel such as SPCC material, and then subjected to heat treatment such as carbonitriding or quenching to improve the strength.

In the case of the above-described normal stopper pin, since heat treatment is performed to secure the strength required for the stopper pin, variation in dimensional accuracy increases, and the stopper pin may fall off from the center hole. In addition, in order to avoid the separation of the stopper pin from the center hole, the cost for managing the dimensional variation of the stopper pin and the heat treatment itself become factors of increasing the cost. Therefore, a stopper pin which is not subjected to heat treatment as described in detail in japanese patent No. 4911062 (patent document 2) has been proposed. Thus, the stopper pin is less likely to be displaced from the opening of the center hole end due to a variation in dimensional accuracy as described later, and is inexpensive.

Specifically, the stopper pin described in patent document 2 is made of a material other than JIS standardSCM415 and S30C are exemplified in addition to the predetermined SPCC material, and are formed from a steel sheet having a carbon content of 0.3 mass% or less, are not quenched and solidified, and have a surface hardness of 100 or more and 300 or less in terms of HV (vickers hardness). The stopper pin described in patent document 2 is manufactured by a forming method such as press forming, and has a substantially bowl shape with a substantially U-shaped cross section or a substantially bowl-shaped cross section

A substantially bowl-shaped. The outer diameter (diameter) of the stopper pin and the inner diameter (diameter) of the opening of the center hole are set to the reference dimension of 6[ mm ]]。

In patent document 2, the force and the drop load required for dropping the stopper pin from the center hole opening are controlled by the outer diameter (diameter) of the stopper pin and the inner diameter (diameter) of the center hole opening. Specifically, in the case where the outer diameter (diameter) of the stopper pin is 6[ 2 ], [ 0.01[ mm ], at most +0.05[ mm ], the tolerance range of the outer diameter (diameter) of the stopper pin is set. In contrast, the tolerance range of the inner diameter (diameter) of the opening portion of the center hole is set to be at least-0.02 [ 2 ], [ mm ], at most +0.01[ mm ].

Prior art documents

Patent document

Patent document 1: japanese utility model registration No. 2604564

Patent document 2: japanese patent No. 4911062

SUMMERY OF THE UTILITY MODEL

Problem to be solved by utility model

Even when the heat treatment is not performed, the stopper pin, which is originally substantially bowl-shaped, has a large variation in outer diameter dimension in view of the characteristics of the forming process. Therefore, in order to reduce the deviation of the drop load, it is necessary to reduce the tolerance of the inner diameter (diameter) of the end opening of the center hole pressed into the stopper pin (for example, the tolerance range of the inner diameter is managed to 0.03[ 2 ], [ mm ] or less). On the other hand, in the inner diameter machining for controlling the inner diameter (diameter) dimension to the accuracy of 0.03[ mm ] or less, since the hole forming machining and the finishing machining are required, controlling the tolerance range of the inner diameter of the center hole to 0.03[ mm ] or less causes an increase in the number of machining steps required for the center hole, an increase in the number of management steps, an increase in the amount of waste due to an increase in the fraction defective, and a decrease in the yield.

In addition, the stopper pin of patent document 2 is not heat-treated, and has a shape with a substantially cross-sectional shape

Since the stopper pin has a substantially bowl shape, when the stopper pin is press-fitted into the center hole of the pinion shaft, the stopper pin is deformed by buckling to reduce the dropping load, which may cause leakage of the lubricating oil.

The present invention has been made in view of the above circumstances, and a first object of the present invention is to provide a stopper pin which is more excellent in dimensional accuracy than the conventional stopper pin having a large deviation in dimensional accuracy and is less likely to come off from the hole of the pinion shaft. A second object of the present invention is to provide a technique that can reduce the number of processing and managing steps for holes compared to conventional techniques.

Means for solving the problems

In order to achieve the above object, the present invention provides a pinion shaft structure including: a pinion shaft that rotatably supports the pinion gear through a bearing provided in a center hole of the pinion gear; a vertical hole formed inside the pinion shaft and extending from one end of the pinion shaft toward the other end; an inlet hole formed inside the pinion shaft and connected to the vertical hole; an outlet hole formed inside the pinion shaft and connected to the vertical hole, the outlet hole communicating the vertical hole with the bearing; and a stopper pin that is press-fitted into one end of the vertical hole to close the vertical hole, wherein the stopper pin is solid, made of an alloy having a copper content of 55 mass% or more and a zinc content of 45 mass% or less, has a surface hardness of 80HV or more and 200HV or less in terms of Vickers hardness, and has a tapered surface having a predetermined slope in an outer periphery of both end portions with respect to an axial center of the stopper pin, the predetermined slope being a slope included in a range of 10 ° to 30 °.

According to the present invention, the stopper pin is not substantially bowl-shaped but solid, so that buckling deformation of the stopper pin can be prevented. The tolerance range of the outer diameter of the stopper pin is smaller than that of the conventional bowl shape, and the dimensional accuracy of the stopper pin is improved. As a result, the tolerance range of the inner diameter dimension of the end opening of the vertical hole into which the stopper pin is press-fitted can be obtained larger than in the conventional art, and the management of the inner diameter dimension of the vertical hole is also reduced as compared with the conventional art. According to the utility model discloses, compare in the past the drop of stop pin and the leakage of lubricating oil can improve. In addition, the rejection rate of the pinion shaft structure is lower than that of the conventional one, and the yield is improved. Further, the stopper pin has a surface hardness (vickers hardness) softer than that of the pinion shaft, and the stopper pin is pressed into the end opening while being elastically deformed, whereby the surface of the stopper pin conforms to the end opening, and the end opening is closed to prevent the stopper pin from coming off. Moreover, heat treatment of the stopper pin is not required, and cost reduction can be achieved.

In one aspect of the present invention, the tolerance range of the outer diameter of the stopper pin is set to 0.040mm or less. According to the above arrangement, since the deviation of the outer diameter dimension of the stopper pin is reduced as compared with the conventional one, the dimensional accuracy of the stopper pin is improved as compared with the conventional one, and the stopper pin is less likely to come off from the vertical hole of the pinion shaft. Further, the tolerance range of the inner diameter dimension of the vertical hole of the pinion shaft pressed into the stopper pin can be increased compared to the conventional art. Therefore, the number of processing and management steps for the vertical hole of the pinion shaft can be reduced as compared with the conventional one, the yield of the pinion shaft can be improved, and the cost can be reduced.

Effect of the utility model

Thus, according to the present invention, the dimensional accuracy of the stopper pin can be improved more than ever, and the stopper pin is difficult to come off from the longitudinal hole of the pinion shaft. Further, since the stopper pin has excellent dimensional accuracy, the number of processing and management steps for the vertical hole of the pinion shaft can be reduced as compared with the conventional case, the yield of the pinion shaft can be improved, and the cost can be reduced.

Drawings

Fig. 1 is a longitudinal sectional view showing a pinion shaft structure according to an embodiment of the present invention.

Fig. 2 is a side view showing the stopper pin of this embodiment taken out.

Description of the symbols:

10 pinion shaft structure, 11 pinion, 12 central hole, 21 pinion shaft, 22 planet carrier, 23 inlet hole, 24 longitudinal hole (hollow hole), 25 outlet hole, 26 stop pin, 27 oil supply path, 28 conical surface, 29 one end opening, 31 bearing, 32 retainer, theta conical surface inclination relative to the axis center of the stop pin.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1 is a longitudinal sectional view showing a pinion shaft structure according to an embodiment of the present invention. Fig. 2 is a side view showing the stopper pin of this embodiment taken out.

Referring to fig. 1, a pinion shaft structure 10 of the present embodiment is a part of a planetary gear mechanism provided in a transmission of an automobile, and includes a pinion gear 11, a pinion shaft 21, and a rolling bearing 31. The pinion 11 is an externally toothed gear having a central hole 12. The center hole 12 extends through the pinion gear 11 from one end surface to the other end surface of the pinion gear 11.

A cylindrical pinion shaft 21 is inserted through a center hole 12 of the pinion gear 11, and a rolling bearing 31 is provided in an annular space defined by an inner peripheral surface (center hole 12) of the pinion gear 11 and an outer peripheral surface of the pinion shaft 21.

The rolling bearing 31 includes a cage 32 and a plurality of rollers 33. The plurality of rollers 33 roll on the inner circumferential surface (center hole) of the pinion gear 11 as an outer raceway surface and the outer circumferential surface of the pinion shaft 21 as an inner raceway surface. The cage 32 has a plurality of pockets arranged at intervals in the circumferential direction, and each of the rollers 33 is provided in each of the pockets to hold the intervals of the plurality of rollers 33, \ 8230. The pinion gear 11 and the pinion shaft 21 constituting the outer/inner raceway surfaces of the rolling bearing 31 are made of a strong material such as bearing steel, carbon steel, or case-hardened steel.

Both ends of the pinion shaft 21 protrude from the pinion gear 11. The carrier 22 is fixed to the end portion. The pinion gears 11 constitute planetary gears, mesh with a sun gear and a ring gear, not shown, and rotate while revolving around the sun gear. The carrier 22 is configured to revolve around the input/output pinion gears 11, is disposed coaxially with the sun gear and the ring gear, and rotates around the central axis of the sun gear. When the pinion gear 11 rotates about the pinion shaft 21, the pinion shaft 21 rotatably supports the pinion gear 11 via the rolling bearing 31. The pinion shaft 21 has a lubricating structure for supplying lubricating oil to the rolling bearing 31 provided in the center hole 12 of the pinion gear 11.

The above-described lubricating structure has the inlet hole 23, the longitudinal hole 24, and the outlet hole 25 formed inside the pinion shaft 21. The vertical hole 24 is bored from one end of the pinion shaft 21 and extends toward the other end. In the present embodiment, the axial center of the vertical hole 24 coincides with a straight line (hereinafter, referred to as an axis) indicating the central axis of the pinion shaft 21.

The inlet hole 23 and the outlet hole 25 of the pinion shaft 21 are respectively bored from the outer peripheral surface of the pinion shaft 21 and extend toward the axis, thereby being connected to the vertical hole 24. In the present embodiment, the inlet hole 23 is disposed at an end portion of the pinion shaft 21, and the outlet hole 25 is disposed at an axial center portion of the pinion shaft 21. The longitudinal hole 24 extends straight in the axial direction of the pinion shaft 21, and the inlet hole 23 and the outlet hole 25 extend straight in a direction different from the axial direction and intersect with the longitudinal hole 24. Specifically, the inlet hole 23 and the outlet hole 25 extend in the radial direction of the pinion shaft 21 and are orthogonal to the vertical hole 24.

The stopper pin 26 is press-fitted into an opening at one end of the longitudinal hole 24 (hereinafter referred to as one-end opening 29). Thus, the oil supply passage 27, the inlet hole 23, the vertical hole 24, and the outlet hole 25 are connected to each other inside the pinion shaft 21 to form an oil supply path extending in a crank shape.

The inlet port 23 is connected to an oil supply path 27 provided in the carrier 22. The outlet opening 25 is connected to a rolling bearing 31. The oil supply passage 27 is a hole formed in the carrier 22.

The lubricating oil flows through the oil supply passage 27, the inlet hole 23, the vertical hole 24, and the outlet hole 25 in this order. Then, the lubricating oil is supplied to the rolling bearing 31 to lubricate the rolling bearing 31.

Referring to fig. 2, annular tapered surfaces 28 are formed on the outer edges of both ends of a cylindrical stopper pin 26. The inclination θ of the tapered surface 28 with respect to the axial center of the stopper pin 26 indicated by the one-dot chain line is a predetermined value included in a range of 10 ° or more and 30 ° or less. Since the taper angles of 10 ° to 30 ° are provided at both ends of the stopper pin 26, the taper surface 28 performs the centering function of the stopper pin 26, the stopper pin 26 is easily pushed into the one-end opening 29 which is a hollow hole in a correct posture, the stopper pin can be prevented from being obliquely pushed and twisted, and the stopper pin 26 can be prevented from being damaged and the lubricant oil can be prevented from leaking. When torqued in, the retaining pin may break, creating a gap that may result in leakage of lubricating oil. Further, since both ends of the stopper pin 26 are inclined at the same angle, the directionality of the stopper pin 26 when it is pressed into the one-end opening 29 is lost, the workability of the pressing is improved, and the cost is reduced.

The outer diameter of the stopper pin 26 having a cylindrical fixed outer diameter and the inner diameter of the longitudinal hole 24 having a fixed inner diameter are defined values included in the range of 2[ 2 ] mm or more and 10[ 10 ] mm or less, for example, 4[ mm ] or 6[ mm ]. In the present embodiment, the diameter tolerance of the stopper pin 26 and the diameter tolerance of the one-end opening 29 pressed into the stopper pin 26 can be set based on the necessary drop load at the design stage.

For example, in the case where the outer diameter of the stopper pin 26 and the inner diameter of the one end opening 29 are both 4[ 2 ] mm ] and the necessary disengagement load is 50[ N ], the tolerance of the outer diameter of the stopper pin 26 is set to +0.03[ 2 ] mm to +0.07[ 0 ] mm, and the tolerance of the inner diameter of the one end opening 29 is set to-0.07 [ 0 ] mm to +0.02[ 0 ]. In this case, the inner diameter tolerance range of the one-end opening 29 is set to 0.09[ mm ], and the inner diameter tolerance range can be widened compared with the conventional one.

The stopper pin 26 of the present embodiment is manufactured by cutting so as to have a predetermined outer diameter. The material of the stopper pin 26 is made of a material that is easy to cut. By the cutting work of the outer diameter, dimensional variation is small compared with the cutting work of the inner diameter, the dimensional accuracy of the stopper pin 26 becomes good, and the tolerance range can be narrowed. Further, since the stopper pin 26 is made of a material having high machinability, the dimensional accuracy of the machined surface is improved, the machining time is shortened, and the production is inexpensive. Alternatively, the stopper pin 26 of the present embodiment is manufactured by upsetting. For example, the wire rod is cut and plastically deformed while applying pressure.

The stopper pin 26 of the present embodiment has good dimensional accuracy and a narrow tolerance range, and therefore, even if the dimensional tolerance of the one-end opening 29 into which the stopper pin 26 is pressed is wide, a necessary releasing force can be secured. According to the present embodiment, the machining productivity of the one-end opening 29 is improved, and the pinion shaft 21 can be produced at low cost.

The surface hardness of the stopper pin 26 is included in the range of 80HV to 200HV in terms of vickers hardness. According to the present embodiment, the stopper pin 26 can be formed without performing heat treatment which increases the cost, and without the risk of breakage or falling.

In order to prevent the drop of the stopper pin, it is necessary to reduce the variation in drop load, and therefore, the variation in the outer diameter dimension of the stopper pin is reduced. In the present embodiment, press forming and heat treatment, which increase the dimensional variation, are not employed in order to reduce the variation in the outer diameter dimension. In place of these machining and processing, in order to finish the pin 26 with a small variation in the outer diameter dimension thereof, a metal having a copper content of 55 mass% or more and a zinc content of 45 mass% or less is subjected to cutting processing to finish the pin 26. Since the metal having the copper content of 55 mass% or more and the zinc content of 45 mass% or less can secure appropriate strength and has excellent ductility, the ease of press-fitting deformation of the stopper pin can be secured, and the adhesiveness to the hole during press-fitting can be improved. Further, since the cutting work is easy, the work with less dimensional variation can be performed. Further, since the alloy does not contain a special alloy component, it is not an expensive metal in terms of price. On the other hand, if the values are outside the above ranges, the tensile strength, the vickers hardness, and the ease of cutting cannot all be ensured.

Examples of the metal material include brass, free-cutting brass of C3604 (JIS, H3250: 2015), and a metal material prepared from JIS, H3250:2015, C3605, C3603, C3602, C3601, C3531, C2800, C2700 and C2600. The material of such stopper pin 26 is softer than the material of the pinion shaft 21.

The reason why the surface hardness of the stopper pin 26 is set in the range of 80HV to 200HV is that if the surface hardness is less than 80HV, the stopper pin itself may be deformed excessively and damaged or come off when the stopper pin 26 is pressed into the vertical hole 24 for introducing the lubricating oil. If the voltage exceeds 200HV, heat treatment or the like is required, which increases the cost.

Incidentally, the machinability can be further improved by containing lead in the metal of the stopper pin, and the dimensional accuracy of the outer diameter of the stopper pin as a machined surface is improved, whereby the dimensional tolerance of the outer diameter of the stopper pin can be controlled to be narrower than in the related art (press forming, heat treatment). As a result, even if the tolerance of the diameter of the opening of the hollow hole to be press-fitted is set in a range wider than that of the conventional art (even if labor is saved in managing the work), the necessary removal force can be stably secured.

In order to facilitate understanding of the operation and effect of the present embodiment, in patent document 2, in order to set the tolerance range of the outer diameter (diameter) of the stopper pin to the minimum of-0.01 [ mm ] and the maximum of +0.05[ mm ], the tolerance range of the stopper pin is set to 0.06[ mm ] widely. In contrast, the tolerance range of the central hole opening is set to be narrow at 0.03[ mm ] so that the tolerance range of the inner diameter (diameter) of the central hole opening is set to be at least-0.02 [ mm ] and at most +0.01[ mm ]. In the case of the above-described conventional example, since a narrow tolerance range is managed in the opening portion of the center hole of the pinion shaft, an increase in cost and an increase in waste amount due to an increase in the number of processing steps such as drilling, reaming, and grinding required for the center hole, an increase in the number of management steps, and an increase in the failure rate are caused.

In the conventional example, when the tolerance range of the outer diameter (diameter) of the stopper pin is set to be at least 0.01[ mu ] m and the tolerance range of the inner diameter (diameter) of the center hole opening is set to be at most +0.01[ mu ] m, a positive clearance is generated between the stopper pin and the center hole opening, and the stopper pin is easily detached.

In contrast, according to the present embodiment, C3604 made of free brass is used as the material of the stopper pin 26, and the outer diameter tolerance of the stopper pin 26 is set to be at least +0.03[ mm ] and at most +0.07[ mm ], and the outer diameter tolerance range of the stopper pin 26 can be narrowed to 0.04[ mm ], so that the inner diameter tolerance range of the diameter of the longitudinal hole 24 into which the stopper pin 26 is pressed can be set to be, for example, 0.09[ mm ] as described above, and therefore, the number of machining steps and the number of management steps can be reduced, the failure rate can be reduced in the manufacturing process of the pinion shaft, and the amount of waste and the management cost of the defective parts can be reduced, as compared with 0.03[ mm ] of the conventional example.

In addition, according to the present embodiment, in the above-described setting of the tolerance, even when the outer diameter dimensional tolerance of the stopper pin 26 becomes the minimum +0.03[ mm ] and the inner diameter dimensional tolerance of the one-end opening 29 becomes the maximum +0.02[ mm ], a negative clearance is secured between the stopper pin 26 and the one-end opening 29, and the stopper pin 26 is prevented from falling out of the one-end opening 29.

Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the configurations of the illustrated embodiments. Various modifications or variations may be applied to the illustrated embodiments within the same scope or equivalent scope as the present invention.

Industrial applicability

The utility model discloses can utilize in mechanical structure and lubricating structure profitably.

Claims

1. A pinion shaft structure includes:

a pinion shaft that rotatably supports the pinion gear through a bearing provided in a center hole of the pinion gear;

a longitudinal hole formed inside the pinion shaft, extending from one end of the pinion shaft toward the other end;

an inlet hole formed inside the pinion shaft and connected to the longitudinal hole;

an outlet hole formed inside the pinion shaft and connected to the vertical hole, the outlet hole communicating the vertical hole with the bearing; and

a stopper pin that is pressed into one end of the vertical hole to close the vertical hole,

the pinion shaft structure is characterized in that,

the stopper pin is solid, made of brass, has a surface hardness of 80HV or more and 200HV or less in terms of Vickers hardness, and has tapered surfaces having a predetermined slope with respect to an axial center of the stopper pin on outer peripheries of both end portions, wherein the predetermined slope is a slope included in a range of 10 ° or more and 30 ° or less.

2. The pinion shaft structure according to claim 1,

the tolerance range of the outer diameter dimension of the stop pin is set to be less than or equal to 0.040 mm.