JPS6324282Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a belt transmission device that prevents belt jumping and prevents belt displacement on pulleys.

In belt transmission devices, when driven at high speed,
Alternatively, when a large load is suddenly applied, the belt stretches and tends to jump on the pulleys, causing the belt to shift sideways and jump out of the groove of the pulley, causing it to slip off or slip on the pulley. I do things. Especially the upper shaft (main drive shaft)
The driven shaft must be accurately synchronized with the main shaft, such as the belt transmission device of a sewing machine that transmits the rotation of The teeth of the belt temporarily became disengaged, causing the teeth of the belt to skip over each other, resulting in synchronization between the two shafts and a timing error.

To solve this problem, conventionally, an idler pulley was installed that was loaded with a spring and pressed against the belt between the two shafts, and when the belt slackened due to belt stretching, it absorbed the slack and kept the belt in a constant state of tension. However, providing such an idler pulley requires a large amount of torque to drive the belt, which makes the machine's movement heavier and places a large load on the drive motor. This tends to cause problems not only in the durability of the belt itself but also in the durability of the entire device.

The purpose of this invention is to obtain a belt transmission device that can prevent jumping without imposing any particular load on the belt.

Embodiments of the present invention will be described below with reference to the attached drawings. In the embodiment shown in FIG. In the delivered belt transmission device, an inverted V-shaped double-armed lever 7 is placed so that it rests against the pulley 4 on the driven shaft side, and whose middle part is rotatably attached to a shaft 6 parallel to the driven shaft 3. A roller 8 that faces the belt 5 on the pulley is pivoted on each free end of the lever 7, and the double-arm lever 7 is swung within a small range until the roller 8 comes into contact with the belt 5. I'm trying to get comfortable.

According to this embodiment, when the belt jumps on the pulley on its slack side and pushes up the roller, the double-arm lever rotates and the other roller presses down on the belt. Equipment that protrudes from the groove, slips or slips, and has a toothed belt like the one shown,
This eliminates the possibility of the belt and pulley becoming disengaged and causing teeth to jump. Furthermore, the belt is pressed against the belt by jumping the belt itself, and there is no need for any external operation to press the belt, and the belt can be automatically and effortlessly prevented from shifting.

In addition, as mentioned above, the belt is pressed only when the belt jumps, and normally there is no contact, or even if there is contact, it is only a light contact, so there is no need for extra torque to drive the belt. .

If the double-arm lever can be rotated, there are the following advantages.

In other words, if the double-arm lever is fixed, if the pulley is eccentric, or there is a dimensional error or installation error in the double-arm lever or roller,
Or, if the thickness of the belt is uneven, in the former case the gap between the rollers and the belt differs depending on each roller, and one roller may be too far away from the belt and the gap is wider than the appropriate gap, or the other may have a gap that is too large. In the latter case, the thick part of the belt comes into contact with the rollers and gets stuck, impairing the smooth movement of the belt. If the arm lever can be rotated, the above-mentioned gap changes, so that the dimensional accuracy and processing accuracy of each part can be relaxed to some extent, and even if the belt is uneven in thickness, running will not be impaired.

In the embodiment shown in FIG. 2, an arm 12 is further provided protruding from a double-arm lever 11 to form a Y-shape, and the middle part of the arm 12 is rotatably attached to the shaft 14 of a pulley 13. A hook groove 15 is formed, and a stopper 16 is loosely fitted into the hook groove 15 with an appropriate clearance, so that the double-arm lever 11 similar to the above embodiment can be rotated slightly.

In addition to producing the same effect as in the above embodiment, this embodiment also controls the swinging range of the double-arm lever by appropriately setting the above clearance, and prevents the roller from coming into contact with the running belt. The load on the belt caused by the rollers is generally not at all or almost unchanged, so that the belt can always run smoothly.

In the embodiment shown in FIG. 1, the swing range of the double-arm lever can also be restricted by, for example, placing pins on the outside of each arm of the double-arm lever.

The double-arm lever as described above may be provided not only on the pulley on the driven shaft side but also on the pulley on the driving shaft side, or even on both pulleys.

Furthermore, in each of the above embodiments, the rollers are pivoted so that when the belt jumps and comes into contact with each free end of the double-arm lever, the roller can run smoothly. directly,
The above effect can also be achieved by suppressing belt jumping.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a belt transmission device according to the present invention, and FIG. 2 is a plan view of main parts of another embodiment. 2, 4...Pulley, 5...Toothed belt, 7...
Double-arm lever, 8...Koro, 11...Double-arm lever,
12... Arm, 13... Pulley, 15... Hook groove, 1
6...Stopper, 17...Koro.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A double-arm lever 7, which is provided with arms extending on both sides and rotatably pivoted on shafts 6 and 14 at the intermediate portion;
11, and each arm of the lever has a pulley 2,
The belt transmission device is provided with a pressing means that faces the belt 5 hung on the pulleys 4 and 13 with an appropriate clearance and presses the belt 5 on the pulley against the pulley by slight rotation of the double-arm lever. (2) The belt transmission device according to claim 1, wherein the holding means is rollers 8 and 17 pivoted on the arm. (3) The belt transmission device according to claim 1, wherein the double-arm lever 7 is supported by a shaft 6 which is arranged parallel to the shafts 1 and 3 on which the pulleys 2 and 4 are mounted. (4) The belt transmission device according to claim 3, wherein the double-arm lever 7 is provided with a regulating means for regulating its swing range. (5) The regulating means is a pin that engages the belt when the double-arm lever 7 is in the swing range.
Belt transmission device as described in section. (6) The double-arm lever 11 has a shaft 1 on which a pulley 13 is attached.
4. The belt transmission device according to claim 1, wherein the belt transmission device is rotatably supported on a shaft by a stopper 16, and the range of swing is regulated by a stopper 16. (7) The belt transmission device according to claim 6, wherein the stopper 16 fits into the hook groove 15 formed in the arm 12 separately provided on the double-arm lever 11 with an appropriate clearance.