JPS6316909Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to improvements in belt transmissions.

Conventionally, typical belt transmission devices include those using flat belts and V-belts, but these devices have the disadvantage that slip occurs when the initial tension is loosened due to belt elongation, making transmission impossible. be.

Next, toothed belt (timing belt) transmission devices have the disadvantage that stitch skipping occurs when a large load is applied, damaging the belt teeth.
This has the disadvantage that even when the belt stretches, skipped stitches occur and the teeth of the belt are damaged.

The present invention is aimed at solving the above-mentioned drawbacks of conventional belt transmission devices, and provides a belt having triangular teeth with an apex angle of 120° or more and 170° or less, and the belt. It is characterized by a combination of pulleys having tooth profiles corresponding to the tooth profiles.

Hereinafter, embodiments of the present invention will be explained based on the accompanying drawings. Fig. 1 is a side view of a belt 1 according to the present invention, and although the belt 1 is made endless, the figure shows about 2 pitches. There is. 2 is a triangular tooth of the belt, and has a rounded radius at the bottom and the top of the tooth. Pituchi P
is determined from the required horsepower, pulley size, etc. Reference numerals 3 and 4 are rubber or rubber-like elastic bodies, and reference numeral 5 is a tensile member made of a cord of glass fiber, polyester, aramid fiber, or the like. Reference numerals 6 and 7 are cover cloths, which are made of cotton cloth, polyamide cloth, or the like. The cover cloth 6 may be omitted depending on the material of the elastic body used in 3 or the purpose, and the cover cloth 7 may also be omitted depending on the material of the elastic body used in 4 or the purpose. Good too. Therefore, four types of structures are possible: one with a cover cloth on both sides, one without a cover cloth on both sides, and one with a cover cloth on either side.

FIG. 3 shows an example of the layout of the transmission device, in which power is transmitted from the driving pulley 8 to the driven pulley 9 via the belt 1. In the figure, there are two axes, but it is of course possible to use a plurality of driven pulleys. It is also possible to provide a tensioner (flat pulley) on the back side of the belt.

Next, to explain the recovery action of the initial tension, FIG. The teeth create a phase difference on the teeth of the pulley, and this has the same effect as moving the pulley by h shown in the figure and retensioning the belt 1. In two-axis transmission, a similar phase difference occurs in the other pulley, and the pulley movement effect is 2h.

In the belt according to the present invention, the teeth of the pulley and the teeth of the belt normally mesh in the same phase as shown in FIG. 3, and power is transmitted mainly through friction. Since there is a mechanical connection between the pulley and the belt through teeth, the transmission capacity is naturally greater than pure frictional transmission.

When the belt 1 stretches, it is possible to continue transmission as explained in the previous section on the initial tension recovery function. However, the elongation of the belt cannot be absorbed without limit, and from the viewpoint of the durability of the belt teeth, the movement effect h is limited to approximately 1/2 of the belt tooth height.

The lengthening of the pitch of the teeth of the belt due to the elongation of the belt is compensated for by a considerable amount by increasing the winding radius of the belt around the pulley, thereby reducing misalignment due to cumulative pitch error.

Next, when an overload condition occurs, a slip occurs between the belt and the pulley to protect the prime mover or the driven machine. Also, even a slight slip will not damage the belt because its teeth are low.

Next, to explain the shape of the teeth of the belt, the shape of the teeth is triangular. This is because it is a convenient shape that can maintain surface contact with each other when a phase difference occurs between the teeth of the belt and the teeth of the pulley.

Regarding the tooth angle, when θ shown in Figure 1 is small (when α is large when viewed from the apex angle α of a triangular tooth), the mechanical bonding effect is small, and recovery in the case of initial tension loosening is difficult. The effect will also be smaller. Furthermore, θ
If α is too small (that is, if α approaches 180°), there will not be much difference from a flat belt.

On the other hand, when θ is large (α is small), the expected slip is less likely to occur. And when a slip occurs, teeth are easily damaged. Furthermore, when a pitch error occurs between the teeth of the pulley and the belt, the teeth of the belt are likely to be damaged.

From the above viewpoint, an angle between 5° and 30° is selected as θ, but when this angle θ is viewed as the apex angle α of the triangular teeth of the belt, α is between 120° and 170°,
A range of 120° to 160° is preferred.

The tips of the teeth are rounded to 1/10 to 1/2 of the pitch to prevent damage to the teeth when the belt slips.
Add. Also, a similar radius is attached to the bottom of the tooth to prevent cracks caused by repeated bending of the belt.

Next, the teeth of the pulley are made to have the same shape as the space formed by the tooth groove of the belt when the belt is bent at the diameter of the pulley around which the belt is wound. When the belt is bent within the range of normal use, the tooth profile of the belt hardly changes.
The teeth of the pulley also have a triangular shape with radius at the tip and bottom.

The tooth profile of the pulley used in the present invention has low teeth and does not require high precision like gears or pulleys for gear transmission or toothed belt transmission, so it can be easily formed by sheet metal forming, sintered metal forming, etc. It is possible to mold it by mass production.

As described above, the present invention improves the transmission capacity by loading the interlocking transmission elements compared to the case of flat belts or V-belts, and when the belt elongates and the initial tension decreases, the belt teeth and pulleys When the teeth of the belt are out of phase and the teeth of the belt ride on the teeth of the pulley, the initial tension is restored, and slips and vibrations due to slack in the belt can be prevented.
Further, noise caused by slips and vibrations can also be prevented.

[Brief explanation of the drawing]

Fig. 1 is a side view of the belt according to the present invention, Fig. 2 is a cross-sectional view along the - line of Fig. 1, Fig. 3 is a side view of an embodiment of belt transmission in combination with a pulley, and Fig. 4 is a side view of the belt and the pulley. FIG. 2 is an explanatory diagram showing the meshing state of the two in a relaxed manner. 1...Belt, 2...Teeth, 8, 9...Pulley.

Claims (1)

[Scope of utility model registration request] A belt transmission device comprising a belt having triangular teeth with an apex angle of 120° or more and 170° or less, and a pulley having a tooth profile corresponding to the belt tooth profile.