JPS5837360A - Power transmitter using tooth-shaped belt - Google Patents

Abstract

PURPOSE:To automatically prevent the lowering of transmission torque due to the lowering of the tension of a tooth-shaped belt by a method in which a combination of an epicyclic gear and a tooth-shaped sprocket is supported through a link on an output shaft, and the epicyclic gear is engaged with a drive gear on the output shaft. CONSTITUTION:A drive gear 7 is fixed to an output shaft 1, and a pair of links 8 are also rotatably supported on the shaft 1. A combination of an epicyclic gear 9 and a tooth-shaped sprocket 2 is rotatably supported on the tip of the links 8, and a tooth-shaped belt 4 is laid across between the tooth-shaped sprocket 2 and the tooth-shaped sprocket on the follow side. Thus, the epicyclic gear 9 engaging with the drive gear 7 revolves around the output shaft 1 by the action of the links 8 while ratating and moved around the drive gear 7. The gear 9 is then stopped at the place where it balances with the tension of the tooth-shaped belt 4 and continues to rotate. In this way, the tension of the tooth- shaped belt 4 is automatically regulated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power transmission device using a toothed belt that can be used for the rear wheel drive of a two-wheeled motor vehicle, etc. The toothed belt stretches due to long-term use. The purpose of this is to automatically apply a predetermined tension to prevent tooth skipping.

Power transmission devices using toothed belts are generally used! As shown in Fig. J1, a toothed sprocket 2 is fixed to the output shaft 1, and a toothed belt 4 is engaged with this and a toothed sprocket 3 on the driven side to transmit power.

However, in this case, as the tension of the toothed belt 4 decreases due to long-term use, the maximum torque that can be transmitted decreases. In other words, when the tension of the toothed belt 4 drops below a certain value due to the elongation of the belt itself, tooth skipping occurs between the teeth of the belt 4 and the sprocket 2, making it impossible to transmit power. (The teeth of belt 4 will be damaged.)

To prevent this, conventionally the rear axle and frame on which the driven side tooth type sprocket 3 is supported (both f'-<1 not shown)
A chain pulling mechanism is provided between them, and when the tension decreases, the distance between the center axes of the sprockets is changed by d in Fig. 2 to reduce the tension of the toothed belt 4 to the imaginary part. As shown in the figure, the belt tensioner 5 is attached to keep the tension of the belt 4 constant.However, the timing of adjusting the 611 (chain puller) differs depending on the user, and it is difficult to expect the effect. Also, in the latter case (one tensioner type), noise is generated from the tensioner.

The present invention eliminates the above-mentioned problems in the conventional system and automatically prevents a decrease in transmission torque caused by an increase in belt tension by employing a planetary gear. shows.

In FIG. 4, a drive gear 7 is fixed to the output shaft 1, and a pair of links 8 are rotatably supported. A combination of a planetary gear 9 and a toothed sprocket 2 (with a center line parallel to the output shaft 1) is supported at the tip of the link 8 so as to be rotatable at the same time. A hook is provided between the toothed sprocket 3 on the driven side and the toothed belt 4 so that the toothed belt 4 meshes therewith, as in the case of FIG. FIG. 4 shows the device according to the invention in its initial set-up, and FIG. 5 shows the belt 4 in its stretched state.

Figure 6 is a partial enlarged view of Figure 4, and Figure 7 is a partial enlargement of Figure 6.
■As is clear from the cross-sectional view in Fig. 7, the link 8.8a is rotatably supported on the output shaft 1 via a bearing 10.11, and the link 8.8a is rotatably supported on the output shaft 1 by a snap ring 13.14. The axial position is fixed. I5 (center line 0l) of planetary gear 9 and toothed sprocket 12
-Ol) has a concentric support shaft 15 at both ends, and the tip iM portion of the link 8.8a is rotatably fitted onto the support shaft 15 via a bearing 16, and is supported by a snap ring 17. The position iff of axis 15 is determined. Bearing 10.11.
16 may be any suitable type such as a flat bearing, needle bearing, or ball bearing. The combined body of the planetary gear 9 and the toothed sprocket 12 may be made of metal by casting or forging, but may also be made of resin with high wear resistance in order to enhance the noise prevention effect.

In FIG. 6, when the drive gear 7 rotates together with the output shaft 1 in the direction of the arrow A, the freewheeling gear 9 that meshes with the drive gear 7 rotates in the direction of the arrow B and rotates in the direction of the arrow C with the output shaft 1 as the center due to the action of the link 8. It revolves, moves upward around the drive gear 7, stops at a position where it balances the tension of the toothed belt 4, and continues to rotate. Due to the above movement of the planetary gear 9,
Tooth type sprocket 12 and driven side tooth type sprocket 3 (
(Fig. 4) increases, and the tension of the toothed belt 4 can be compensated (5th P21).

As explained above, in the present invention, the planetary gears 9 and 1
117 '12 Link the sprocket 12 assembly8.
The planetary gear 9 was engaged with the drive gear 7 on the output shaft 1, and the toothed belt 4 was passed around the toothed sprocket 12 and the toothed sprocket 3 on the driven side. Therefore, by utilizing the revolution movement of the idler gear 9 on the drive gear 7, it is possible to automatically correct a decrease in tension due to elongation of the toothed belt 4, etc., and prevent a decrease in the transmitted torque. In addition, conventionally, as another means of preventing the tooth skipping phenomenon, it was necessary to widen the belt width, but when the present invention is adopted, it is not necessary to widen the belt width to prevent the tooth skipping phenomenon ψ. (Since the toothed belt with the minimum width necessary for power transmission can be used, the axial width of the power transmission device portion can be shortened, and the device can be made compact.

It should be noted that when implementing the invention, instead of using two links 8.8a, one link can also be arranged between the planetary gear 9 and the toothed sprocket 12.

[Brief explanation of drawings]

Fig. 1 is a front view showing the general structure of a power transmission device using a toothed belt, Figs. 2 and 3 are front views of a power transmission device employing a conventional tension drop prevention mechanism, and Fig. 4 The figure shows a front view 112+ of the power transmission device according to the present invention, FIG. 5 is a front view showing the belt of the device shown in FIG. 4 in an extended state, and FIG. 6 is a partially enlarged view of FIG. 4. 21, Figure 7 is the ■− of Figure 6.
■It is a sectional view. 1...Output shaft, 3...Tooth sprocket, 8.8a...Link, 9...-Planetary gear, 12
...Tooth sprocket patent applicant Kawasaki Heavy Industries, Ltd.

Claims (1)

[Claims] A combination of a planetary gear and a toothed sprocket is supported on the output shaft via a link so that its center line is parallel to the output shaft, and the planetary gear is meshed with a linear gear on the output shaft to form a toothed sprocket. A power transmission device using a toothed belt, characterized in that a toothed belt is passed over a toothed sprocket on the driven side.