JP2019163776A - Gear structure - Google Patents

Abstract

To provide a gear structure which can inhibit hit sound and roaring sounds occurring when gears engaged at low costs.SOLUTION: A gear structure according to the disclosure includes: a gear 1 having a spline hole 2 at its center; a spline shaft 3 which is loosely fitted in the spline hole 2 to support the gear 1; and a cushioning material 4 disposed between a tooth surface 8c of the gear 1 which defines the spline hole 2 and a tooth surface 9c of the spline shaft 3.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a gear structure.

  As a method for suppressing the hitting sound and the swell sound generated when the gears mesh with each other, there are known a method of controlling the heat treatment strain and measuring the accuracy of the paired gears and selecting a gear combination.

  Further, as a method for more effectively suppressing the hitting sound and swell sound, there is a method of performing a gear grinding finish or a gear honing finish after heat-treating the gear. According to this method, the cumulative pitch accuracy of the gear, which is one of noise generation factors, is also improved.

Japanese Patent Laid-Open No. 9-14396

  However, the gear grinding finish and the gear honing finish require a dedicated machine such as a gear grinding machine and a honing machine, and thus there is a problem that the manufacturing cost increases.

  Accordingly, the present disclosure has been made in view of such circumstances, and an object thereof is to provide a gear structure that can suppress a hitting sound and a swell sound generated at the time of meshing of the gears at low cost.

According to one aspect of the present disclosure,
A gear having a spline hole in the center;
A spline shaft that is loosely fitted in the spline hole and supports the gear;
A cushioning material interposed between the tooth surface of the gear defining the spline hole and the tooth surface of the spline shaft;
A gear structure is provided.

  Preferably, the gear and the spline shaft are spaced apart over the entire circumference, and the cushioning material is interposed between the gear and the spline shaft over the entire circumference.

  The gear and the spline shaft are spaced over the entire circumference, and a pressure angle is set between the tooth surface of the gear and the tooth surface of the spline shaft that define the spline hole, and the tooth tip of the spline shaft An air gap may be formed between the surface and the tooth bottom surface and the gear, and the cushioning material may be interposed between the spline shaft and the tooth surface of the gear.

  Further, among the tooth surfaces of the gears defining the spline hole, the tooth surface facing in the circumferential direction is brought into contact with the tooth surface of the opposing spline shaft, and the tooth surface facing in the other circumferential direction is opposed. It is spaced apart from the tooth surface of the spline shaft, and the cushioning material may be interposed between the spaced tooth surfaces.

  In addition, a gap is formed between the tooth tip surface and the tooth bottom surface of the spline shaft and the gear, and a pressure angle is set on the tooth surface of the gear and the tooth surface of the spline shaft that defines the spline hole. May be.

  Further, at least one of the tooth tip surface and the tooth bottom surface of the spline shaft may be in contact with the gear.

  According to the present disclosure, it is possible to suppress the hitting sound and the swell sound generated when the gears mesh with each other at low cost.

It is a front view of the gearwheel concerning one embodiment of this indication. It is AA arrow sectional drawing of FIG. It is a principal part enlarged view of FIG. It is a principal part enlarged view of the gearwheel which shows other embodiment. It is a principal part enlarged view of the gearwheel which shows other embodiment. It is a principal part enlarged view of the gearwheel which shows other embodiment.

  Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

  FIG. 1 is a front view of the gear 1 according to the present embodiment, and FIG. 2 is a cross-sectional view of the gear 1 according to FIG.

  As shown in FIGS. 1 and 2, the gear structure according to the present embodiment includes a gear 1 having a spline hole 2 in the center, a spline shaft 3 that is loosely fitted in the spline hole 2 and supports the gear 1, and A shock-absorbing material 4 interposed between the gear 1 defining the spline hole 2 and the spline shaft 3 is provided.

  The gear 1 is constituted by an external gear. The gear 1 includes a rim portion 5 formed on the outer periphery, a boss portion 6 formed on the inner periphery, and a web portion 7 formed between the boss portion 6 and the rim portion 5.

  On the outer periphery of the rim portion 5, teeth 5a for meshing with other gears are formed. The tooth 5a is formed by an involute curve of the cross-sectional shape of the tooth surface. That is, the gear 1 is composed of an involute gear. The rim portion 5 is formed to have an axial dimension larger than that of the web portion 7. The gear 1 is not limited to an involute gear. The gear 1 may be another type of gear such as a cycloid gear.

  The boss 6 has a spline hole 2. As shown in FIG. 3, the spline hole 2 is configured by forming a plurality of spline grooves 6 b extending in the axial direction at equal intervals in the circumferential direction on the inner peripheral surface of the shaft hole 6 a formed at the center of the boss portion 6. . Thereby, an inner peripheral loose fitting surface 8 that is loosely fitted to the spline shaft 3 is formed on the boss portion 6.

  The inner peripheral loose fitting surface 8 extends in the radial direction between a tooth tip surface 8a formed between the spline grooves 6b, a tooth bottom surface 8b formed by the groove bottom of the spline groove 6b, and between the tooth tip surface 8a and the tooth bottom surface 8b. And a tooth surface 8c for transmitting torque.

  A pressure angle θ is set on the tooth surface 8c. The pressure angle θ is an angle of the tooth surface 8c with respect to the radial direction of the gear 1, and is set larger than 0 °. As a result, the tooth surface 8c is inclined so as to face radially inward. Further, the boss portion 6 is formed to have an axial dimension larger than that of the web portion 7.

  The web part 7 is formed in a thin plate shape with an equal thickness.

  The spline shaft 3 is formed by forming a plurality of spline grooves 3a extending in the axial direction on the outer peripheral surface of a shaft rod having a circular cross section at equal intervals in the circumferential direction. As a result, the spline shaft 3 is formed with an outer peripheral loose fitting surface 9 loosely fitted with the inner circumferential loose fitting surface 8 of the gear 1.

  The outer peripheral loose fitting surface 9 extends in the radial direction between a tooth tip surface 9a formed between the spline grooves 3a, a tooth bottom surface 9b formed by the groove bottom of the spline groove 3a, and between the tooth tip surface 9a and the tooth bottom surface 9b. And a tooth surface 9c for transmitting torque.

  The tooth tip surface 9a of the outer peripheral loose fitting surface 9 is formed so as to be separated from the tooth bottom surface 9b of the inner peripheral loose fitting surface 8 in the radial direction. The tooth bottom surface 9b of the outer peripheral loose fitting surface 9 is formed so as to be separated from the tooth tip surface 8a of the inner peripheral loose fitting surface 8 in the radial direction. Further, the tooth surfaces 9c of the outer circumferential loose fitting surface 9 are formed so as to be spaced apart from the tooth surfaces 8c of the inner circumferential loose fitting surface 8 in the circumferential direction. Thereby, the spline shaft 3 is separated from the gear 1 over the entire circumference.

  Further, a pressure angle θ corresponding to the inner circumferential loose fitting surface 8 is set on the tooth surface 9 c of the outer circumferential loose fitting surface 9. The pressure angle θ of the tooth surface 9 c of the outer peripheral loose fitting surface 9 is set to be the same as the pressure angle θ of the tooth surface 8 c of the inner peripheral loose fitting surface 8. Thereby, the tooth surface 9c of the outer periphery loose fitting surface 9 and the tooth surface 8c of the inner periphery loose fitting surface 8 become parallel. In addition, the spline hole 2 and the spline shaft 3 may be configured by an involute spline, an involute serration, or a key groove.

  The shock absorbing material 4 includes a gear side shock absorbing material layer 4a coated on the inner peripheral loose fitting surface 8 of the gear 1 and a shaft side shock absorbing material layer 4b coated on the outer peripheral loose fitting surface 9 of the spline shaft 3. The The gear side cushioning material layer 4a is coated on the entire inner circumferential loose fitting surface 8 with a uniform thickness. The shaft-side cushioning material layer 4b is coated on the entire outer surface loosely fitting surface 9 with a uniform thickness. The gear-side cushioning material layer 4a and the shaft-side cushioning material layer 4b are formed to have substantially the same thickness. The shock absorbing material 4 constituting the gear side shock absorbing material layer 4a and the shaft side shock absorbing material layer 4b is made of nylon. Nylon is coated on the inner circumferential loose fitting surface 8 and the outer circumferential loose fitting surface 9 by an immersion flow method or an electrostatic coating method.

  Further, the nylon coating film is processed in advance into a predetermined uniform film thickness by a hob or a die. When nylon is coated with a substantially uniform film thickness, processing for adjusting the film thickness by a hob or a die may be omitted.

  The gear-side cushioning material layer 4 a and the shaft-side cushioning material layer 4 b are press-fitted by fitting the inner circumferential loose fitting surface 8 and the outer circumferential loose fitting surface 9. As a result, the cushioning material 4 is interposed between the inner circumferential loose fitting surface 8 and the outer circumferential loose fitting surface 9 without any gap, and the gear 1 is attached to the spline shaft 3 with high accuracy.

  The buffer material 4 may be coated only on one of the inner circumferential loose fitting surface 8 and the outer circumferential loose fitting surface 9.

  The cushioning material 4 is not limited to nylon. For example, the buffer material 4 may be composed of other resins such as rubber. In the case where the cushioning material 4 is made of rubber, the spline shaft 3 is loosely fitted in advance to the spline hole 2 of the gear 1 in an accurate positional relationship, and the rubber is inserted into the inner peripheral loose fitting surface 8 by an injection molding method or the like while maintaining this state. And it is good to make it vulcanize-bond to the outer periphery loose fitting surface 9. Thereby, the gear 1 can be accurately attached to the spline shaft 3 via the rubber.

  Even when the cushioning material 4 is made of rubber or the like, after coating rubber or the like on either or both of the inner circumferential loose fitting surface 8 and the outer circumferential loose fitting surface 9, The circumferential fitting surface 9 may be fitted.

  Next, the operation of this embodiment will be described.

  When the gear 1 is rotationally driven in a state of meshing with another gear (not shown), the teeth 5a of these gears 1 periodically contact each other. For this reason, the striking sound and vibration that the teeth 5a hit each other are generated. However, in the gear structure according to the present embodiment, when the teeth 5a hit each other, the cushioning material 4 is slightly deformed to absorb the impact. For this reason, a striking sound and vibration are suppressed.

  In particular, in the gear structure according to the present embodiment, the shock absorbing material 4 is interposed between the inner peripheral loose fitting surface 8 of the gear 1 and the outer peripheral loose fitting surface 9 of the spline shaft 3. It follows the shape of the surface 8 and the outer peripheral loose fitting surface 9 and is bent in a zigzag manner. For this reason, when the teeth 5a hit each other, not only the cushioning material 4 positioned between the tooth surfaces 8c and 9c, but also the cushioning material 4 between the tooth bottom surface 8b and the tooth tip surface 9a adjacent thereto, The buffer material 4 at the position is deformed while interfering in a complicated manner, and the shock and vibration transmitted to the buffer material 4 are quickly absorbed by the buffer material 4 and quickly damped. Furthermore, since the buffer material 4 is in a state of being closely packed in a narrow space bent in a zigzag manner, the buffer material 4 at each position does not move excessively, and the vibration is efficiently damped.

  Further, a general gear profile has a machining error corresponding to the machining accuracy, and this machining error causes a change in the frequency of the impact sound. Then, a plurality of hitting sounds having slightly different frequencies interfere with each other to generate a swell sound.

  However, in the gear structure according to the present embodiment, when the tooth surfaces 8c and 9c having a large machining error hit each other, the cushioning material 4 deforms relatively large, and when the tooth surfaces 8c and 9c having a small machining error hit each other, The material 4 is deformed relatively small. For this reason, the influence of the machining error on the impact sound frequency can be suppressed, and the generation of the undulation sound can be suppressed.

  Furthermore, when one tooth 5a enters the meshing portion between the gears 1 and meshes with the other tooth (not shown), forces in a direction repelling each other are generated between the teeth 5a, and the teeth 5a are separated from each other. When that power disappears. Then, as these gears 1 continue to rotate, the repulsive force is generated and disappears.

  However, in the gear structure according to the present embodiment, the shock absorbing material 4 between the tooth tip surfaces 8a and 9a and the tooth bottom surfaces 8b and 9b facing each other can be slightly deformed to absorb the force in the repulsive direction described above. It is possible to reduce vibration due to the periodic generation and disappearance of this force.

  In addition, conventional gears have been designed to reduce the vibration and noise by increasing the processing accuracy of the contact surfaces of the gears by grinding and optimizing the profile, but considerable processing is required for grinding such high-precision gears. Time-consuming and dedicated processing machines such as gear grinding machines and honing machines are necessary, and the manufacturing cost is high.

  However, according to the gear structure according to the present embodiment, it is possible to suppress a striking sound and a swell sound generated when the gear 1 meshes without pursuing high processing accuracy by a dedicated processing machine, and to improve quietness. , Vibration noise can be reduced. And since the profile of the gear 1 should just be finished with construction methods, such as shaving, the gear 1 can be manufactured at low cost.

  Further, the processing accuracy of the contact surface of the gear depends on the processing machine, and it is not possible to obtain processing accuracy exceeding the limit of the processing machine. For this reason, in the field where high quietness and low vibration are required, there may be a case where the effect of reducing the meshing excitation force of the gear becomes insufficient. However, according to the gear structure according to the present embodiment, the meshing excitation force of the gear can be adjusted by individually adjusting various conditions such as the rebound characteristics, the expansion / contraction characteristics, and the thickness of the cushioning material according to the vibration characteristics of the gear. Can be sufficiently reduced.

  In addition, an electric vehicle (a vehicle that is driven only by the driving force of an electric motor without an internal combustion engine) that has been actively developed in recent years has less noise and vibration of a drive source than a vehicle that has an internal combustion engine. For this reason, it is possible that the performance regarding a noise and a vibration is calculated | required by the gear more than before. Therefore, by adopting the above-described gear structure according to the present embodiment for an electric vehicle, it is possible to reduce noise and vibration generated at the time of gear meshing at low cost, and to achieve low noise and low vibration of the electric vehicle at low cost. it can.

  The basic embodiment of the present disclosure has been described in detail above, but the present disclosure can also be implemented in the following other embodiments.

  (1) As shown in FIG. 4, the gear 1 and the spline shaft 3 are separated over the entire circumference, and a gap 10, between the tooth tip surface 9 a and the tooth bottom surface 9 b of the spline shaft 3 and the gear 1, 11 is formed, and the cushioning material 4 may be interposed only between the spline shaft 3 and the tooth surfaces 8c and 9c of the gear 1. In this case, a pressure angle θ may be set between the tooth surface 8 c of the gear 1 that defines the spline hole 2 and the tooth surface 9 c of the spline shaft 3. As a result, the radial position of the gear 1 is regulated by the cushioning material 4.

  As described above, the cushioning material 4 only needs to be interposed between the tooth surface 8 c of the gear 1 that defines at least the spline hole 2 and the tooth surface 9 c of the spline shaft 3. Thereby, the striking sound and the swell sound generated when the gear 1 is engaged can be suppressed.

  (2) Further, as shown in FIG. 5, among the tooth surfaces 8 c of the gear 1 defining the spline hole 2, the tooth surface 8 c facing in the circumferential direction contacts the tooth surface 9 c of the opposing spline shaft 3. The tooth surface 8c facing the other in the circumferential direction may be separated from the tooth surface 9c of the opposing spline shaft 3, and the cushioning material 4 may be interposed between the separated tooth surfaces 8c, 9c.

  In addition, a pressure angle θ may be set on the tooth surface 8 c of the gear 1 that defines the spline hole 2 and the tooth surface 9 c of the spline shaft 3. In this case, gaps 13 and 14 may be formed between the tooth tip surface 9 a and the tooth bottom surface 9 b of the spline shaft 3 and the gear 1.

  (3) Further, as shown in FIG. 6, the tooth tip surface 9 a of the spline shaft 3 may abut on the tooth bottom surface 8 b of the gear 1 that defines the spline hole 2. According to this, the radial position of the gear 1 with respect to the spline shaft 3 can be stabilized. Although not shown, the tooth bottom surface 9 b of the spline shaft 3 may be in contact with the tooth tip surface 8 a of the gear 1 that defines the spline hole 2. Further, the tooth tip surface 9 a of the spline shaft 3 is brought into contact with the tooth bottom surface 8 b of the gear 1 defining the spline hole 2, and the tooth bottom surface 9 b of the spline shaft 3 defines the spline hole 2. It is good also as what is contact | abutted by 8a.

  That is, at least one of the tooth tip surface 9 a and the tooth bottom surface 9 b of the spline shaft 3 may be in contact with the gear 1.

  The configurations of the above-described embodiments can be combined partially or wholly unless there is a particular contradiction. The embodiment of the present disclosure is not limited to the above-described embodiment, and includes all modifications, applications, and equivalents included in the concept of the present disclosure defined by the claims. Therefore, the present disclosure should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present disclosure.

1 gear 2 spline hole 3 spline shaft 4 cushioning material 8c tooth surface 9c tooth surface

Claims (6)

A gear having a spline hole in the center;
A spline shaft that is loosely fitted in the spline hole and supports the gear;
A cushioning material interposed between the tooth surface of the gear defining the spline hole and the tooth surface of the spline shaft;
A gear structure characterized by comprising: The gear and the spline shaft are spaced over the entire circumference,
The gear structure according to claim 1, wherein the cushioning material is interposed over the entire circumference between the gear and the spline shaft. The gear and the spline shaft are spaced over the entire circumference,
A pressure angle is set on the tooth surface of the gear defining the spline hole and the tooth surface of the spline shaft,
A gap is formed between the tooth tip surface and the tooth bottom surface of the spline shaft and the gear,
The gear structure according to claim 1, wherein the cushioning material is interposed between the spline shaft and a tooth surface of the gear.   Of the tooth surfaces of the gear defining the spline hole, the tooth surface facing in the circumferential direction is in contact with the tooth surface of the facing spline shaft, and the tooth surface facing in the other circumferential direction is the facing spline. 2. The gear structure according to claim 1, wherein the gear structure is spaced from a tooth surface of the shaft, and the cushioning material is interposed between the spaced tooth surfaces. A gap is formed between the tooth tip surface and the tooth bottom surface of the spline shaft and the gear,
The gear structure according to claim 4, wherein a pressure angle is set between a tooth surface of the gear partitioning the spline hole and a tooth surface of the spline shaft.   The gear structure according to claim 4, wherein at least one of a tooth tip surface and a tooth bottom surface of the spline shaft is in contact with the gear.

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