JPH0663554B2 - Toothed belt transmission - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a toothed belt transmission device, and more specifically, it is applied to a transmission device using a prime mover that generates a maximum torque that is several times the steady torque at startup. The present invention relates to a toothed belt transmission device.

[Conventional technology]

BACKGROUND ART Conventionally, a transmission device using a toothed belt has been widely used as a synchronous transmission winding device. This toothed belt transmission transmits power in a state in which the belt tension side expands and the belt slack side loosens as the load torque increases, so a prime mover that generates a maximum torque of several times the steady torque at startup is used. When used, the amount of slack on the belt slack side suddenly increases, and the initial trouble that causes the tooth tip of the loose toothed belt to ride up on the tooth inclination part of the driven pulley on the entry side of the driven pulley and cause the tooth jump phenomenon occurs. There was a drawback that it would occur.

Therefore, in order to solve such a problem, the maximum load including starting time is taken into consideration, and a toothed belt having a strength that can withstand the load is used, and a means for preventing the tooth jump phenomenon is shown in FIG. As shown, the back side of the toothed belt slack side V ₁ is pressed by the tension roller R _S urged by the spring S, or the toothed belt V enters the driven pulley D as shown in FIG. A roller R is provided on the back surface of the toothed belt V ₂ in order to forcibly prevent the tooth jump phenomenon, and has been proposed and implemented.

[Problems of conventional technology]

However, designing the strength of the toothed belt to the maximum permissible stress among the above methods makes the width or thickness of the toothed belt too large, and in the case of a small device, it is necessary to make the device compact. It has the drawback of being difficult to implement.

In the method shown in FIG. 9, the toothed belt slack side V ₁
As the amount of slack in the spring increases, the amount of expansion of the spring S increases, so the pressing force weakens, and as the load torque increases, the tooth jump phenomenon tends to occur, and its effect is insufficient as a device for preventing the tooth jump phenomenon. There was a problem.

In addition, this method requires a relatively small diameter tension roller R _S
Since the toothed belt is pressed against the toothed belt V ₁ , excessive bending is repeated in the toothed belt, resulting in a problem that the durability of the toothed belt is impaired.

Further, the method of FIG. 10 can surely prevent the tooth jumping phenomenon, but since the belt tooth is forcedly pushed into the pulley groove by the contact at one point, the toothed belt has an excessive concentration force. Therefore, there is a drawback that the durability is significantly reduced.
Further, when the load torque increases, the number of meshing teeth on the drive pulley decreases, and there is a problem that the tooth jump phenomenon easily occurs on the drive pulley.

[Problems to be Solved by the Invention]

In view of the above-mentioned problems, the present invention provides a toothed gear having a strength range capable of stably transmitting a normal drive torque even in a transmission device using a prime mover that produces a torque several times as large as a steady torque at the time of startup. The belt can be used, and the tooth jumping phenomenon can be effectively prevented without applying excessive force such as bending to the toothed belt,
As a result, the object is to provide a highly durable toothed belt transmission device.

[Technology that has solved the problem]

That is, in the toothed belt transmission device of the present invention, a toothed belt and a high-modulus pressing belt having an inner peripheral length slightly shorter than the outer peripheral length of the toothed belt are superposed between two or more toothed pulleys. It is characterized in that initial tension is applied only to the high-modulus pressing belt.

[Action]

In the present invention, as shown in FIG. 1, a toothed belt 2 having a high modulus is wound between two or more toothed pulleys 1A and 1B, and as shown in FIG. A high modulus pressing belt 3 having an inner circumference length slightly shorter than an outer circumference length is superposed and mounted, and in this state, an initial tension is applied only to the pressing belt 3.

The initial tension is applied by tensioning the holding belt 3 by adjusting the shafts of the toothed pulleys 1A and 1B, and by tensioning the tension pulley R ₃ against the holding belt 3 as shown in FIG. The initial tension may be added by carrying out.

In the above, as the toothed belt 2, a normal toothed belt 2 in which an elastic body such as rubber or polyurethane is embedded with a core body such as glass fiber or Kevlar, and as the pressing belt 3, rubber, polyurethane or the like is used. In addition to the elastic body in which a core body such as a glass fiber Kevlar is embedded, an endless steel belt or a belt made of a resin film, for example, a flat belt is used.

At this time, if the inner peripheral length of the high-modulus pressing belt 3 is longer than the outer peripheral length of the toothed belt 2, when the initial tension is applied, the tension is applied to the toothed belt 2 and the pressing belt 3 is applied. It cannot take on the function of holding the slack side tension. Further, the inner peripheral length of the pressing belt 3 is the toothed belt 2
Is much shorter than the outer peripheral length of the toothed belt 2 in FIG.
Of the toothed belt 2 on the opposite side becomes inconvenient.

The ratio of the lengths cannot be unequivocally determined by the tensile strength and elongation of both the toothed belt 2 and the pressing belt 3, but it may be approximately longer than the outer peripheral length of the toothed belt 2.
When there are two A and 1B, as described above, it is within the range of the length that does not contact the inside of the toothed belt 2 on the opposite side.

If the number of toothed pulleys is three or more, as shown in FIG. 3, the toothed belt hardly contacts the inner side of the toothed belt 2 on the opposite side, so the length limitation is smaller than the above.

In the present invention, the initial tension for the toothed belt 2 is
As is clear from FIGS. 1 to 3, it is zero, and the initial tension is exclusively taken up by the pressing belt 3.

Next, when a load torque is applied, tension is applied to the tension side of the toothed belt 2 by an amount corresponding to the load torque as shown in FIG. Therefore, nothing is applied to the toothed belt 2 other than the tension required for power transmission, and the toothed belt 2 has only the function of power transmission.

On the other hand, since the pressing belt 3 is simply overlapped with the outer circumference of the toothed belt 2, it is possible to slide between them, and when driving is started, it is rotated together with the toothed belt 2 due to friction between the two. Ready to go. Therefore, the pressing belt 3 is only applied with the initial tension and is not responsible for transmitting power at all, but is solely responsible for retaining the tension on the slack side.

As described above, since the toothed belt 2 is responsible only for power transmission and the pressing belt 3 is only responsible for holding the initial tension, when the load torque is increased, the swelling of the toothed belt 2 on the slack side only increases. The slack side tension never decreases. Further, when an excessively large load torque is applied and the tooth top of the toothed belt 2 tries to ride on the tooth top of the pulley on the entry side of the driven pulley, the holding belt 3 has a high modulus, and therefore the riding force increases. As a result, the tension of the pressing belt 3 increases, and the tooth jump phenomenon can be effectively prevented.

Further, as is clear from FIG. 2 or FIG. 3, the pressing belt 3 presses the entire wound portion with a uniform force according to the curvature of the wound portion of the toothed belt 2 around the pulleys 1A and 1B.
No excessive force such as bending is applied to the toothed belt 2.
Further, since the pressing belt 3 presses both the drive pulley 1A and the driven pulley 1B, the tooth jump phenomenon on both pulleys 1A and 1B can be prevented at the same time.

Since the toothed belt 2 and the pressing belt 3 according to the present invention are integrally wound and wound around the toothed pulleys 1A and 1B, as shown in FIG. The pulleys 1A and 1B may be provided with flanges 4 and 4 having a height capable of receiving both.

Further, as shown in FIGS. 6 and 7, concave and convex stripes 2A and 3A may be provided on the back surface of the toothed belt 2 and the inner surface of the pressing belt 3 so as to be fitted in a male and female relationship with each other.

Further, since the toothed belt 2 and the pressing belt 3 rotate together while slipping slightly on the contact surfaces, it is preferable that the friction between them is low in terms of transmission efficiency.

〔Example〕

 Next, an embodiment of the present invention will be described.

Kevlar fiber is embedded in the tensile strength body made of polyurethane, toothed belt 2 of Table 1 specifications, drive pulley 1A whose shaft center is movable with 28 teeth, and shaft core fixed with 28 teeth. Loosely wrap it around the driven pulley 1B, then wrap it gently over the flat belt made of polyurethane of Table 2 with Kevlar fiber embedded as a tensile strength member as the pressing belt 3 and then move the shaft core of the drive pulley 1A. Initial tension was applied.

Table 1 Table 2 Toothed belt specifications Holding belt specifications Outer circumference length 1210mm Inner circumference length 1200mm Width 15mm Width 15mm Backside thickness 2mm Total thickness 1.5mm Belt pitch 8mm ------- Number of teeth 150 teeth ----- As shown in FIG. 2, the toothed belt 2 bulges inward by about 20 mm on both the tension side and the slack side, and the holding belt 3 is in a tensioned state.

The drive pulley 1A and the driven pulley 1B both have flanges, and the flange 4 has a height of 5 mm and a tooth width of 16 mm.
And

Therefore, the positional relationship between the toothed belt 2 and the pressing belt 3 is regulated by the flange 4.

When the drive pulley was rotated in this state, the inward bulge on the side on which the toothed belt 2 was stretched instantly moved to the slack side, resulting in the state shown in FIG.

[Performance test of examples]

The belt transmission according to the above embodiment is applied with four levels of initial tension, the drive pulley 1A is rotated at 750 rpm, and the load torque is gradually applied to the driven pulley 1B, causing the toothed belt 2 to jump. The load torque on the verge of the occurrence of was read and the graph of FIG. 8 was obtained. In FIG. 8, in Comparative Example 1, only the toothed belt 2 equivalent to that in Example was used, and the drive pulley 1A was moved without the pressing belt 3 to read the tooth jump torque when the initial tension was varied by four levels. In Comparative Example 2, the toothed belt 2 equivalent to that of the example was used, and the initial tension was given by pressing the tension roller biased by the spring to the belt slack side as shown in FIG. is there.

As is clear from FIG. 8, it was confirmed that the examples were extremely excellent in tooth jumping torque resistance in any initial tension state.

〔effect〕

As described above, in the belt transmission device according to the present invention, the toothed belt 2 and the pressing belt 3 share the power transmission function and the initial tension holding function, and hold down even when the load torque increases. Since the tension of the belt 3 increases and the tooth jump phenomenon can be effectively prevented, it can be applied even when using a prime mover that generates a maximum torque that is several times the steady torque at startup.

Therefore, unlike the conventional case, it is not necessary to use a wider belt than necessary, so that the device can be made lightweight and compact.

Further, unlike the conventional tooth jump prevention device using a tension roller, the tooth jump phenomenon can be prevented without applying an excessive force such as bending to the toothed belt 2, so that the durability of the toothed belt 2 is impaired. It is possible to provide a highly durable toothed belt transmission device.

[Brief description of drawings]

1 to 3 are side views of an embodiment of the present invention, FIG. 4 is a side view of another embodiment, and FIG. 5 is a sectional view of essential parts of a toothed pulley of the embodiment, FIG. 6 and FIG. FIG. 7 is a cross-sectional view of a main part of a toothed pulley of another embodiment, FIG. 8 is a graph showing the relationship between initial tension and tooth jump torque of the embodiment, and FIGS. 9 and 10 are side views of a conventional example. Is.

Claims (3)

[Claims] 1. A toothed belt and a high-modulus pressing belt having an inner circumferential length slightly shorter than the outer circumferential length of the toothed belt are overlapped and wound between two or more toothed pulleys, and the high-modulus pressing belt. A toothed belt transmission characterized in that an initial tension is applied only to the toothed belt. 2. The toothed belt transmission according to claim 1, wherein the toothed pulley is provided with a flange having a height capable of receiving both the toothed belt and the high modulus holding belt. 3. The toothed belt transmission according to claim 1, wherein a concavo-convex ridge is formed on the back surface of the toothed belt and the inner surface of the high-modulus pressing belt so that they can be fitted in a male-female relationship with each other. apparatus.