JPH07198000A - Gear transmission device - Google Patents

Abstract

PURPOSE:To lower production cost, and shorten production time by letting a gear main body having a tooth section on one side surface in the axial direction, and a shaft section which is stretched in a row to the inner circumference section of the gear main body while being extended outward in the axial direction beyond one side surface of a tooth section main body, be integrated by means of forging into a bevel gear, and letting it be removably supported by a gear case via bearings. CONSTITUTION:A gear main body 4 including a tooth section 4a of a bevel gearing 3, and a shaft section 5 which is stretched in a row to the inner circumference section of the gear main body 4 while being extended outward in the axial direction beyond one side surface (f) at the tooth section side, are integrally formed by means of forging. Therefore, there is no need for cutting the tooth section into a gear as in the past, production cost is lowered and production time is thereby shortened that much. Since the integration of the gear main body 4 and the shaft section 5 permits the shaft section 5 to be free from profile limitation imposed by an escape from a gear cutter, high degree of freedom can thereby be secured in the formation and constitution of the shaft section 5 itself.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear transmission, and particularly to a gear body having teeth formed on one side surface in the axial direction, and a shaft portion extending axially outward from the one side surface of the gear body. A bevel gear such as a bevel ring gear is rotatably supported in a gear case via a bearing interposed between the shaft portion and the gear case.

[0002]

2. Description of the Related Art Conventionally, a tooth portion of a bevel gear used in a gear transmission of the above type has been formed by gear cutting. In order to avoid the interference between the gear cutting cutter and the gear shaft portion (refer to the shaded portion X in FIG. 8) during the gear cutting process, conventionally, as shown in, for example, Japanese Utility Model Publication No. 4-23054, a gear body is used. The shaft part and the shaft part are formed separately, and the two parts are attached later by welding or the like.

[0003]

However, in the case where the gear body and the shaft portion are separately manufactured and then integrally joined as in the above-described conventional art, the gear cutting time for the tooth portion of the gear body is long, and the parts are Since the number of points is large, productivity is poor as a whole, there is a limit to cost reduction, and the accuracy of the entire bevel gear is controlled by the accumulation of machining and assembly errors (the accuracy of each individual gear body and shaft and the accuracy of coupling). There is also a problem that becomes difficult.

The present invention has been made in view of such circumstances, and an object thereof is to provide a gear transmission capable of solving the above problems.

[0005]

In order to achieve the above object, the present invention provides a gear main body having a tooth portion on one side in the axial direction,
A bevel gear is formed by forging integrally with a shaft portion that is continuous with the inner peripheral portion of the gear body and extends axially outward from the one side surface of the gear body, and configures a bevel gear. The feature is that the gear case is supported through a bearing.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, referring to FIGS. 1 to 7, when the gear transmission of the present invention is applied to a front wheel differential device and a rear wheel final gear device of a saddle-ride type four-wheel vehicle for running on uneven terrain, respectively. An example will be described. FIG. 1 is a schematic overall side view showing an embodiment of a vehicle to which the present invention is applied, FIG. 2 is a plan sectional view of a final gear device for rear wheels (enlarged sectional view taken in the direction of arrow 2 in FIG. 1), and FIG. Cross-sectional view of the differential device for a vehicle (enlarged cross-sectional view taken along arrow 3 in FIG. 1), FIG. 4 is a perspective view of the material before forging, FIG. 5 is a vertical cross-sectional view showing the outline of the primary forging device, and FIG. FIG. 7 is a vertical sectional view showing the outline of the forging device, and FIG. 7 is a vertical sectional view showing the outline of the tertiary forging device.

First, in FIG. 1, a saddle-ride type vehicle V has a power unit P including an engine mounted in the center of a vehicle body B, and a pair of left and right front wheels steered by a steering wheel H at the front portion of a vehicle body F. Wf and a pair of left and right rear wheels Wr are suspended at the rear portions thereof. The power unit P
Is transmitted to the front wheel differential device D via the front wheel propeller shaft Sf and is transmitted to the left and right axles Af to drive the left and right front wheels Wf. At the same time, the power from the power unit P is transmitted to the rear wheel final gear device FG via the rear wheel propeller shaft Sr, and from there to the left and right axles Ar to drive the left and right rear wheels Wr.

As shown in FIG. 2, the rear wheel final gear device FG includes a housing 1 as a gear case, and a ball bearing B ₁ and a needle bearing B ₁ ′ in the housing 1.
A ball bearing B having a bevel pinion gear 2 which is supported via _And a bevel ring gear 3 which is supported via ₂ .

The bevel ring gear 3 constitutes the bevel gear of the present invention, which has a tooth portion 4 on the left side face f.
A ring-shaped gear body 4 having a formed therein and a shaft portion 5 that is continuous with the inner peripheral portion of the gear body 4 and extends axially outward from both left and right side surfaces of the gear body 4 are integrally formed by forging. The ball bearings B ₂ are formed between the outer circumferences of the left and right ends of the shaft portion 5 and the corresponding inner circumferences of the housing 1 by molding. The shaft portion 5 is formed hollow and the left and right rear axles Sr are fitted to the inner peripheral surface thereof. The tooth portions 2a and 4a of the bevel pinion gear 2 and the bevel ring gear 3 are
Is formed immediately (straight bevel gear) to eliminate the undercut.

The tooth portion 2a of the bevel pinion gear 2 is integrally formed with a connecting flange portion 2af that fills each tooth groove in a water-slip shape at the large-diameter end portion, and the tooth portion is specially provided. Since the teeth of 2a are integrally connected to each other, the tooth portion 2a can be reinforced. Further, the main shaft portion 2j of the bevel pinion gear 2 is formed in a stepped manner, the inner peripheral portion of the bearing B ₁ is fitted to the outer peripheral base portion thereof, and the outer peripheral intermediate portion thereof has a cylindrical shape for interlocking with the propeller shaft Sr. The spline member S is spline-fitted, and a retaining nut N is screwed onto the tip of the outer periphery thereof.

On the other hand, the front wheel differential device D is supported by an axle housing 11 as a gear case and a ball bearing B ₃ and a needle bearing B ₃ ′ in the axle housing 11 as shown in FIG. Bevel pinion gear 1 that rotates in conjunction with the front end of the front wheel propeller shaft Sf
2 and a bevel ring gear 13 supported by a ball bearing B ₄ in the axle housing 11 with a tooth portion 14a meshing with the tooth portion 12a of the bevel pinion gear 12.
It has and.

The bevel ring gear 13 constitutes the bevel gear of the present invention. It comprises a ring-shaped gear body 14 having a tooth portion 14a formed on the left side face f ', and the gear body 14 A bowl-shaped differential case cap 16c that is continuous with the peripheral portion and a shaft portion 15 that extends axially outward from the left side surface of the differential case cap 16c are integrally formed by forging, and the outer periphery of the shaft portion 15 and the housing are formed. Ball bearings B ₄ are respectively interposed between the corresponding inner circumferences of 11 and 11. The shaft portion 5 is formed in a hollow shape, and the left front axle Af is inserted into the inner peripheral surface of the shaft portion 5. The bevel pinion gear 12
Also, the tooth portions 12a and 14a of the bevel ring gear 13 are also
It has a straight bevel gear to eliminate undercut.

The differential case cap 16c is an ax
Ball bearing B in the housing 11 _FourSupported through
Bowl-shaped differential case book that supports the pinion shaft 17
It is attached to the body 16m so as to close the opening,
The differential case body 16m and the differential case cap 16c
The differential case 16 is composed of. Of the differential case 16
The internal structure is similar to that of a conventionally known differential device,
That is, the pinion shaft 17 has a pair of bevel diff pinio.
18 are supported and they are attached to the bevel diff pinion 18.
Is the left side bevel gear fitted to the left front axle Af
19 and the front axle on the right side where the differential case body 16m is inserted
The right side bevel gear 19 'fitted to Af is left and right.
Are engaged with each other.

Tooth portion 12a of the bevel pinion gear 12
Is integrally formed with a connecting flange portion 12af that fills each tooth groove in a large-diameter end portion, and each tooth of the tooth portion 12a is integrally connected by the special provision of the connecting flange portion 12af. Therefore, the tooth portion 12a can be reinforced. The main shaft portion 12j of the bevel pinion gear 12 is formed on the stepped, that is the outer peripheral base portion is an inner circumferential portion fitted in the bearing B ₃ ', also in its outer peripheral middle portion, the cylinder of the propeller shaft Sf interlocked The spline member S'is spline-fitted, and a retaining nut N'is screwed on the outer peripheral tip end portion thereof.

Next, the manufacturing process of the bevel ring gear 3 used in the rear wheel final gear device FG will be described with reference to FIGS. FIG. 5 shows the cylindrical material 20 shown in FIG.
Shows a primary forging device A1 for forging into a preform 21 in which a large diameter portion 21a is formed at the center in the axial direction and a small diameter portion 21b is formed at both ends. This primary forging device A
1 is a fixed lower mold 22 having a molding surface 22a corresponding to the shape of the lower surface of the preform 21, and the preform 21
And a movable upper die 23 having a molding surface 23a corresponding to the upper surface shape of the upper die 23. The upper die 23 has a ring holder 24 that engages with an outer peripheral step of the upper die 23. It is integrated with the upper base by fixing it with a bolt or the like.

At the center of the upper mold 23, a pair of upper and lower knives are provided.
Checkout pin N₁, N₂Are arranged in columns, of which the bottom is
Side knockout pin N₁Is always returned by the return spring 25
It is urged and the lower end surface is a part of the upper molding surface 23a.
Composed and upper knock ant pin N₂Forging
After that, as the upper die 23 rises, the lower knockout pin N ₁
Against the biasing force of the return spring 25 and the molding surface 23 of the upper mold 25.
The preform 21 is projected downward from the a
It functions as a mold release. On the other hand, in the center of the lower mold 22
Also, a pair of upper and lower knockout pins N₃, N_FourArranged in columns
The upper knockout pin N₃The upper end surface of
It constitutes a part of the molding surface 22a of the lower die 22 and also has a lower surface.
Quanto Pin N_FourAfter forging, the upper knockout
Topin N ₃Is projected above the molding surface 22a of the lower mold 22.
Machine to separate the preform 21 from the lower mold 22.
To work.

Further, FIG. 6 shows a secondary forging apparatus A2 for forging the preformed product 21 into an intermediate molded product 26 having a disk-shaped flange portion 26f at the axial center, and FIG. , The flange portion 26f of the intermediate molded product 26,
A tertiary forging apparatus A3 for forming the gear main body 4 having the tooth portion 4a and forming the small-diameter portions 26b, 26b 'of both ends of the intermediate molded product 26 on the shaft portion 5 is shown. These secondary and tertiary forging devices A2 and A3 have basically the same structure as the primary forging device A1 except that the upper and lower mold surfaces are different from each other. Element and corresponding primary forging device A
Reference numerals of “1” and “″” are attached to the reference numerals of the main constituent elements of No. 1 and the description thereof is omitted.

In order to manufacture the bevel ring gear 3, first, the upper die 23 of the primary forging device A1 is preliminarily held at the upper standby position, and the columnar shape as shown in FIG. By placing the raw material 20 (at this time, the raw material is appropriately heated in advance), and then lowering the upper mold 23 and strongly pressing the raw material 20 between the upper mold 23 and the lower mold 22. Then, the preform 21 is molded.
Next, the preform 21 is removed from the primary forging device A1, transferred to the secondary forging device A2, and the preform is formed between the upper die 23 and the lower die 22 of the secondary forging device A2 in the same procedure. The intermediate molded product 26 having a disk-shaped flange 26f at the center in the axial direction is molded by strongly pressing 21.

Next, this intermediate molded product 26 is removed from the secondary forging device A2, transferred to the tertiary forging device A3, and in the same procedure, intermediate molding is performed between the upper die 23 and the lower die 22 of the tertiary forging device A3. By strongly pressing the product 26, the flange portion 26f of the intermediate molded product 26 is molded on the gear body 4 having the tooth portion 4a, and the small-diameter portions 26b and 26b 'of both ends of the intermediate molded product 26 are shrunk. 5 to form the final molded product 27. Gear body 4 of this final molded product 27
An annular burr 28 is attached to the outer peripheral edge of the burr 28, and this burr 28 is removed by cutting in a subsequent deburring step. Further, since the shaft portion 5 of the final molded product 27 is not hollow, a through hole is formed in the shaft portion 5 in the subsequent hole making step, and further, the surface and the inner surface of the final molded product 27 can be machined if necessary. It is applied to finish those surfaces.

In this way, the bevel ring gear 3 is connected to the gear body 4 including the tooth portion 4a and the inner peripheral portion of the gear body 4, and is axially outward from one side surface f of the gear body 4 on the tooth portion side. Since the shaft portion 5 extending to the
It is not necessary to cut the tooth portion 4a as in the prior art, and the processing cost and the processing time are shortened accordingly. Moreover, the gear body 4 and the shaft portion 5 are integrated so that the shaft portion 5 can be formed. Since there is no restriction on the shape considering the clearance from the gear cutting cutter, a high degree of freedom can be secured in the shape and configuration of the shaft portion 5 itself. In addition, since the gear body 4 and the shaft portion 5 are integrated to reduce the number of parts, the cumulative tolerance is reduced and the accuracy control of the entire bevel ring gear 3 is facilitated.

As for the bevel ring gear 13 of the front wheel differential device D, the rear wheel final gear device FG is also used.
In the same way as when forging the bevel ring gear 3 of
The gear body 14, the differential case cap 16c, and the shaft portion 15 are integrally formed by forging, and the tooth portion 14a is also integrally formed by the forging. After that, each part is subjected to necessary machining.

Further, the bevel pinion gears 2 and 12 of the front wheel differential device D and the rear wheel final gear device FG are integrally integrated in the same manner as in the case of forging the bevel ring gears 3 and 13. It is formed by forging, and the teeth 2a, 12a and the connecting flange 2a are formed by the forging.
f and 12af are also integrally formed. After that, each part is subjected to necessary machining.

[0023]

As described above, according to the present invention, a gear main body having a tooth portion on one side surface in the axial direction, and a gear main body connected to the inner peripheral portion of the gear main body in the axial direction outer side than the one side surface. Since the bevel gear is formed by integrally molding the shaft portion extending to the shaft by forging, the tooth portion of the gear body can be simultaneously molded when the gear body and the shaft portion are forged, and the tooth portion is conventionally formed. Therefore, it is possible to contribute to the reduction of the processing cost and the processing time as well as the shape and configuration of the shaft itself by integrating the gear body and the shaft. A high degree of freedom can be secured. Further, since the number of parts is reduced by integrally molding the gear main body and the shaft portion, not only can the cost be further reduced, but also the cumulative tolerance is reduced and the accuracy control of the entire bevel gear is facilitated.

[Brief description of drawings]

FIG. 1 is a schematic overall side view showing an embodiment of a vehicle to which the present invention is applied.

FIG. 2 is a plan sectional view of a final gear device for rear wheels (enlarged sectional view taken in the direction of arrow 2 in FIG. 1).

FIG. 3 is a plan sectional view of a front wheel differential device (enlarged sectional view taken along arrow 3 in FIG. 1).

[Figure 4] Perspective view of the material before forging

FIG. 5 is a vertical sectional view showing the outline of a primary forging device.

FIG. 6 is a vertical sectional view similar to FIG. 5, showing an outline of a secondary forging device.

FIG. 7 is a vertical sectional view similar to FIG. 5, showing an outline of a tertiary forging device.

FIG. 8 is a sectional view of a gear showing a relationship between a conventional bevel ring gear shaft portion and a gear cutting cutter.

[Explanation of symbols]

1 ……………… Housing as gear case 3,13 ………… Bevel ring gear as bevel gear 4,14 ………… Gear body 4a, 14a… Teeth 5,15 ……… Shaft 11 ………… ...... Axle housing as gear case f, f '... ...... Left side surface as one side surface B ₂ , B ₄ ...... Ball bearing as bearing

Claims (1)

[Claims] 1. A tooth portion (4) on one side surface (f, f ') in the axial direction.
a, 14a) having a gear body (4, 14) and the gear body (4, 14) connected to the inner peripheral portion of the gear body (4, 14).
The bevel gears (3, 13) are integrally formed by forging with the shaft portions (5, 15) extending axially outward from the one side surface (f, f ') of 14), and the bevel gears (3, 13) are formed. The shaft portion (5, 15) of the gear (3, 13) is attached to the gear case (1, 11) by a bearing (B
Characterized in that the bearing through _2, B _4), the gear transmission.