JPH0893886A - Gear transmission device - Google Patents

Abstract

PURPOSE: To enable an auxiliary gear and a pinion to transmit motive power to a speed reducing gear in a state where backlash is zero and to reduce tooth striking sound by fluctuation of the number of rotation of a power shaft by constituting the auxiliary gear to hold it by an elastic body in a state where the auxiliary gear is slightly shifted in the rotational direction against a speed reducing pinion. CONSTITUTION: A boss part 10 is formed on a side surface of a primary drive gear 4 in a gear transmission device engaging a primary driven gear 8 provided on a counter shaft with the drive gear 4 provided on a crankshaft 2. A scissors gear 12 to engage with the driven gear 8 with the drive gear 4 is fit in this boss part 10 free to rotate. Thereafter, the scissors gear 12 is held by springs 14... in a state where it is slightly shifted in the rotational direction against the drive gear 4, and a side surface of an oil pump drive gear 16 adjacent to the drive gear 4 is used as a thrust receiver of the scissors gear 12. Consequently, backlash of the gears 12, 4 is kept zero.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a gear transmission.

[0002]

2. Description of the Related Art As an example of a conventional gear transmission, a primary transmission for an engine of a motorcycle is shown in FIG. Figure 9
[Fig. 3] is a cross-sectional view of an engine of a motorcycle. This primary transmission is a speed reducer between the engine outlet and the transmission, and includes a crankshaft a as a power takeout shaft and a key b.
A primary drive gear (primary reduction small gear) c fixed via a primary drive gear (primary reduction gear) that is provided on a counter shaft f and meshes with the primary drive gear c to transmit power to the counter shaft f via a clutch e. Large gear) d.

By the way, in the engine of a motorcycle, the engine speed is extremely high in order to make the engine small and to provide high output. Therefore, it is necessary to take a large total reduction ratio of the engine, and accordingly, the primary transmission is a large reduction gear. Therefore, conventionally, in the above-described primary transmission, there is a problem of meshing noise between the primary drive gear c and the primary driven gear d, which is particularly noticeable when the engine speed changes.

In order to solve this problem, in the conventional primary transmission shown in FIG. 9, a scissors gear (auxiliary gear) h is attached to the primary driven gear d via a compression coil spring g. That is, the load of the incorporated spring g causes the scissors gear h and the primary driven gear d to engage the teeth of the primary drive gear c, that is, the backlash is always zero so that the scissors gear h and the primary driven gear d mesh with the primary drive gear c. The striking sound is reduced.

[0005]

However, in the above-mentioned conventional primary transmission, since the scissors gear h is mounted on the primary driven gear d having a large outer diameter, the shape of the scissors gear h also corresponds to the primary driven gear d. Is large and thin. Therefore, in the manufacturing process of the scissors gear h, inconvenience occurs such that heat treatment distortion is likely to occur.

Further, since the inertial force of the scissors gear h itself is large, it is necessary to set the load of the spring g to a large value in order to follow the rotational fluctuation, which is disadvantageous to the gear rattle noise. Will be.

Further, since the primary driven gear d is provided integrally with the clutch housing e1, mounting the scissors gear h on the primary driven gear d complicates the structure around the clutch e, and the device is There is also a problem that it becomes expensive or the assembling work of the scissors gear h becomes troublesome.

The present invention has been made in view of the problems of the above-described conventional gear transmission, and it is easy to manufacture and assemble the auxiliary gear, and at the same time, it is small in size so that meshing noise is suppressed to a minimum. An object is to provide an inexpensive gear transmission.

[0009]

The present invention has the following constitution in order to solve the above problems. That is, the present invention is a gear transmission including a reduction small gear provided on a driving shaft and a reduction large gear provided on a driven shaft and meshing with the reduction small gear to transmit power from the driving shaft to the driven shaft. In the above, a boss portion is formed on a side surface of the reduction gear, and an auxiliary gear that meshes with the reduction gear and the reduction gear is rotatably fitted to the boss, and the auxiliary gear serves as the reduction gear. On the other hand, the gear transmission is characterized in that it is held by an elastic body while being slightly displaced in the rotational direction, and the side surface of a component adjacent to the reduction gear on the drive shaft is a thrust receiver of the auxiliary gear. Is.

[0010]

According to the present invention, since the auxiliary gear is held by the elastic body while being slightly displaced in the rotational direction with respect to the reduction gear, the auxiliary gear and the reduction gear are provided with the reduction gear. In meshing with the gear, the gear is engaged with the reduction gear by the load of the elastic body. That is, the auxiliary gear and the small gear transmit power to the reduction gear large gear with zero backlash. As a result, it is possible to reduce gear rattling noise due to fluctuations in the rotational speed of the driving shaft.

Further, in the present invention, since the auxiliary gear is provided on the reduction gear side, the shape of the auxiliary gear is not thin and has a large outer diameter. Therefore, deformation such as heat treatment distortion in the manufacturing process of the auxiliary gear is small. Therefore, the auxiliary gear can be manufactured easily and accurately.

Further, since the outer diameter of the auxiliary gear is small, the inertial force of the auxiliary gear itself becomes small, so that the followability to the rotational fluctuation becomes good without setting the load of the elastic body to a large value. Therefore, the meshing noise in the gear is suppressed to a minimum.

Further, since the auxiliary gear is fitted to the boss portion of the reduction gear and is held by the elastic body, and the side surface of the adjacent component is used as the thrust receiver of the auxiliary gear, the auxiliary gear is mounted. The structure around the auxiliary gear is simplified and the auxiliary gear can be easily assembled.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a motorcycle engine. FIG. 1 is a sectional view of an engine according to the first embodiment. FIG. 2 is an enlarged view of part A in FIG. FIG. 3 is a view corresponding to FIG. 2 showing a modification of the first embodiment. FIG. 4 is a sectional view taken along line IV-IV in FIG. Figure 5
[FIG. 3] is a view showing a primary drive gear according to the first embodiment, in which (a) is a longitudinal sectional view and (b) is a front view. 6A and 6B are views showing a scissors gear according to the first embodiment, where FIG. 6A is a front view and FIG. 6B is a vertical sectional view.

The gear transmission of the first embodiment is, as shown in FIGS. 1 and 2, a primary drive gear (an example of a reduction gear) provided on a crankshaft 2 which is a driving shaft on the power take-out side of an engine. 4 and a primary driven gear (an example of a reduction gear) 8 that is provided on a counter shaft (an example of a driven shaft) 6 and that meshes with a primary drive gear 4 to transmit power from the crankshaft 2 to the counter shaft 6. .

As shown in FIGS. 2 and 4, this gear transmission has a boss portion 10 formed on a side surface of the primary drive gear 4 and a scissors gear (auxiliary gear) which meshes with the primary drive gear 4 together with the primary driven gear 8. (Corresponding to a gear) 12 is rotatably fitted to the boss portion 10, and the scissors gear 12 is held by a compression coil spring (an example of an elastic body) 14 while being slightly displaced in the rotational direction with respect to the primary drive gear 4. A side surface of an oil pump drive gear (an example of an adjacent component) 16 adjacent to the primary drive gear 4 on the axis of the crankshaft 2 is used as a thrust receiver of the scissors gear 12.

As shown in FIG. 1, the crankshaft 2 is rotatably supported on both left and right sides by ball bearings 20, 20 fixed to a side wall of a crankcase 18, and has a central portion in its axial direction. Is the piston 22
Is connected to the large end of the connecting rod 24 provided at the upper end. In addition, as shown in FIG.
A key groove 26a of a key 26 for coupling the primary drive gear 4 and the oil pump drive gear 16 to the crankshaft 2 is formed at the shaft end on one side.

The primary drive gear 4 is shown in FIG.
As shown in (a) and (b), the key groove 26b of the key 26 is provided, and the boss portion 10 is integrally projectingly provided on a side surface of the key 26 on the outer side of the engine.
The boss portion 10 is provided with three spring slits 10a in the rotational direction.

As shown in FIGS. 6A and 6B, the scissors gear 12 is set to have a width dimension slightly smaller than the width dimension of the boss portion 10 and slightly smaller than the outer diameter of the boss portion 10. It has a large inner diameter. Further, three slits 12a respectively corresponding to the three slits 10a of the boss portion 10 are formed in the inner diameter portion. The corresponding slits 10a and the slits 12a are about 1 m in the rotational direction with respect to each other in a state where the teeth of the scissors gear 12 and the teeth of the primary drive gear 4 are aligned with each other in a side view.
They are arranged and formed so as to be displaced by m.

As shown in FIG. 2, the oil pump drive gear 16 is connected to the crankshaft 2 via a key 26 and meshes with an oil pump driven gear 28 to circulate oil used for lubrication and the like. An oil pump (not shown) for the crankshaft 2
It is operated by utilizing the rotation of. The oil pump drive gear 16 shown in FIG. 2 has the side surface on the chamfered 16a side facing the scissors gear 12 side in the same direction as in the conventional case, while the oil pump drive gear 16 shown in FIG. The pump drive gear 16 may have a straight shape without chamfering the side surface, and the straight side surface may support the spring 14 securely.

The above components are assembled to the crankshaft 2 in the following order. The primary drive gear 4 is fitted into the crankshaft 2 so that the boss portion 10 faces the shaft end side, and the key 26 is inserted over the key grooves 26a and 26b. Primary driven gear 8 on counter shaft 6
Fit. The scissors gear 12 is fitted into the boss portion 10 of the primary drive gear 4, the slit 10a of the boss portion 10 and the corresponding slit 12a are aligned, and the spring 14 is inserted between them. After the oil pump drive gear 16 is fitted in the crankshaft 2 in a predetermined direction, the nut 30 is screwed onto the shaft end of the crankshaft 2 so that the oil pump is provided between the inner ring side surface of the ball bearing 20 and the nut 30. The drive gear 16 and the primary drive gear 4 are fixed in the axial direction.

In this assembled state, the scissors gear 12 is sandwiched between the side surface of the primary drive gear 4 and the side surface of the oil pump gear 16, but the width dimension of the scissors gear 12 is the width of the boss portion 10. Since it is set to be slightly smaller than the size, it is held by the spring 14, but is in a state of being freely rotatable against the load of the spring 14.

According to the gear transmission of the first embodiment assembled as described above, the slits 12a and 10a are slightly displaced from each other in the rotational direction as described above.
In the state where the spring 14 is incorporated, a force that sandwiches the teeth of the primary driven gear 8 is generated between the teeth of the primary drive gear 4 and the teeth of the scissors gear 12 due to the load of the spring 14, which causes the primary drive gear 4 and the primary driven gear 4. The state of meshing with 8 is no backlash.

Therefore, the scissors gear 12 is provided on the side of the reduction gear, that is, on the side of the primary drive gear 4 so that the rattling noise due to the fluctuation of the rotation speed of the crankshaft 2 is reduced. Since it is not necessary to make the outer diameter large and thin, the deformation such as heat treatment distortion in the manufacturing process of the scissors gear 12 is reduced, and the scissors gear 12 can be manufactured easily and accurately.

Further, since the outer diameter of the scissors gear 12 is small, the inertial force of the scissors gear 12 itself is small, and thus the followability to the rotational fluctuation is improved without strongly setting the load of the spring 14. Therefore, the interlocking sound can be suppressed to the minimum.

Further, the scissors gear 12 is mounted only by fitting the scissors gear 12 to the boss portion 10 and holding it by the spring 14 and using the existing oil pump drive gear 16 which is an adjacent component as the thrust receiver of the scissors gear 12. Therefore, the structure around the scissors gear 12 can be simplified, and the scissors gear 12 can be easily assembled.

Next, the second embodiment will be described. Figure 7
FIG. 6 is a sectional view showing a gear transmission of the second embodiment. Figure 8
FIG. 8 is a sectional view taken along line VIII-VIII in FIG. 7.

In the second embodiment, as shown in FIGS. 7 and 8, the bearing 20 of the primary drive gear 4 is used.
A boss portion 10 is formed on the side surface (on the center side of the engine), and a scissors gear 12 is rotatably fitted to the boss portion 10 via a boss portion 34a of a spacer (an example of an adjacent component) 34. In addition, the spacer 34 and the scissors gear 12 have torsion springs 14A whose both ends are hooked on the spacer 34 and the scissors gear 12, respectively.
Is elastically held by. Further, the boss portion 34a of the spacer 34 and the boss portion 10 of the primary drive gear 4 are fixed in the rotational direction by a pin 36 so that the deviation in the rotational direction of the scissors gear 12 is set to a predetermined numerical value. The pin 36 is a spacer 34.
In addition to the means for fixing the scissors gear 12 to the scissors gear 12, the scissors gear 12 also serves as a rotation stopper for preventing the scissors gear 12 from rotating too much during assembly.

According to this second embodiment, the scissors gear 1
2, the torsion spring 14A and the pin 36
Since it is elastically held in a state where it is slightly displaced in the rotational direction with respect to the primary drive gear 4, between the teeth of the primary drive gear 4 and the teeth of the scissors gear 12, as in the first embodiment, Primary driven gear 8
A force for sandwiching the tooth is generated, and the meshing state between the primary drive gear 4 and the primary driven gear 8 becomes no backlash as in the first embodiment.

Further, in the second embodiment, the same effect as in the first embodiment can be obtained, and at the same time, the number of parts of the spring is only one, so that the device can be simplified accordingly, and the assembling work of the device can be further facilitated. The remarkable effect of becoming is obtained. Further, since the number of parts is reduced, the cost can be reduced.

The above-described first and second embodiments are preferred embodiments of the present invention, and the technical scope of the present invention is not limited to these embodiments. For example, the first and second embodiments apply the present invention to the primary reduction gear of a motorcycle engine, but the gear transmission of the present invention includes a reduction gear and a reduction gear. It is applicable to all gear transmissions.

[0032]

As described above, according to the present invention, the auxiliary gear can be easily manufactured and assembled. In addition, it is possible to minimize the noise caused by the meshing of the gears, and it is possible to configure the device in a small size and at a low cost.

[Brief description of drawings]

FIG. 1 is a sectional view of an engine according to a first embodiment.

FIG. 2 is an enlarged view of part A in FIG.

FIG. 3 is a diagram corresponding to FIG. 2 showing a modification of the first embodiment.

4 is a sectional view taken along line IV-IV in FIG.

5A and 5B are diagrams showing a primary drive gear according to the first embodiment, wherein FIG. 5A is a longitudinal sectional view and FIG. 5B is a front view.

6A and 6B are views showing a scissors gear according to the first embodiment, in which FIG. 6A is a front view and FIG. 6B is a vertical sectional view.

FIG. 7 is a sectional view showing a gear transmission according to a second embodiment.

8 is a sectional view taken along line VIII-VIII in FIG.

FIG. 9 is a sectional view of an engine showing a conventional gear transmission.

[Explanation of symbols]

2 Crankshaft (an example of a driving shaft) 4 Primary drive gear (an example of a reduction small gear) 6 Counter shaft (an example of a driven shaft) 8 Primary driven gear (an example of a reduction large gear) 10 Boss part 12 Scissors gear (corresponding to an auxiliary gear) 14 Compression Coil Spring (Example of Elastic Body) 14A Torsion Spring (Example of Elastic Body) 16 Oil Pump Drive Gear (Example of Adjacent Parts) 34 Spacer (Example of Adjacent Parts)

Claims (1)

[Claims] 1. A gear transmission including: a reduction small gear provided on a drive shaft; and a reduction gear that is provided on a driven shaft and meshes with the reduction small gear to transmit power from the drive shaft to the driven shaft. A boss portion is formed on a side surface of the reduction gear, and an auxiliary gear that meshes with the reduction gear and the reduction gear is rotatably fitted to the boss, and the auxiliary gear with respect to the reduction gear. The gear transmission is characterized in that the side surface of a component adjacent to the reduction gear on the driving shaft serves as a thrust receiver of the auxiliary gear while being held by an elastic body while being slightly displaced in the rotational direction.