KR830002541B1 - Electric pulley - Google Patents

Abstract

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Description

Electric pulley

1 is a longitudinal sectional view of a preferred embodiment of a pulley according to the present invention in engagement with a belt to form a positive drive.

2 is an enlarged fragmentary longitudinal sectional view of the pulley.

FIG. 3 is an enlarged fragmentary longitudinal sectional view of the second FIGURE pulley shown simultaneously in superimposition on the drawing of a joining pulley according to the patent of Miller.

4 is an enlarged fragmentary longitudinal sectional view of the second degree pulley engaged with the belt according to the patent of "Miller" under no load.

The present invention relates to a geared transmission belt and a pulley.

US Patent No. 2,507,852 to R. Y. Case describes an electric belt consisting of an unstretched tension member having teeth bonded to one side and a protective jacket fabric covering the teeth. The teeth are preferably made of an elastic material such as rubber and the belt may have the same or similar support layer as the material forming the teeth.

Many other elastomeric materials have been used in the manufacture of belts according to the patent of the "case" and the most common materials are neoprene and polyurethane. The belt is designed to engage a toothed pulley formed of a material having a higher Young's modulus than the elastic material used to make the belt. Conventional toothed belts, such as the "case" patent, utilize teeth that are very similar to conventional 9ack teeth and have a trapezoidal cross-sectional shape. Many attempts have been made to modify the tooth shape of the belt and pulley to eliminate the problem of belt breakage. Common belt failures in such trapezoidal belts are shear failures of the teeth due to stress concentration.

As a way to reduce shear of such teeth, US Pat. No. 3,765,091 to "H. Miller" describes a belt tooth having a cross-sectional shape close to the shape of a half wavelength under a limited rated load. The groove of the pulley according to the patent of "Miller" engages and almost joins the belt tooth. The belt with curved teeth according to the "Miller" patent reduced the shear of the belt teeth and increased the horsepower. One form of failure in such shaped belts is due to wear of the belt grooves in small diameter pulleys. Wear of the grooves between the belt teeth is due to the wear of the protective layer and the exposure of the tension member by the action of the pulley on the belt. Wear of these grooves causes premature failure of the belt due to cutting of teeth from the tensioning member and / or cutting of the tensioning member.

U.S. Patent No. 4,037,485 to "Hoak" poses a solution to the problem of abrasion of the grooves. As described in the patent of Hobak :, the relationship between the tooth and the groove of the belt and the tooth and the groove of the pulley is such that the height of the belt tooth is greater than the depth of the pulley groove and the belt The outermost surface portion of the belt tooth facing the pulley is brought into contact with the portion of the pulley forming the bottom of the poly groove when driving. It is described that the belt tooth is compressed so that its height is reduced to come into contact with the belt portion between the belt teeth to be formed.

In the relatively early stages of the operating life of the geared belts and pulleys described in the patent of "hawkback", the compression coupling of the belt teeth of the elastic material to the bottom of the pulley grooves results in a permanent permanent deformation of the belt teeth. This deformation is accelerated at high operating temperatures that occur in application to the automation device, which deformation permanently reduces the height of the teeth. The deformed tooth can no longer support the tuck member. It also appears in the drive of the toothed belt and pulley according to the patent of the "hawk" of the wear mode as in the toothed transmission form according to the patent of Miller.

According to the present invention it is found that the problem of land wear of the patents of "Mirror" and "Hack" can be almost reduced, thereby increasing the operating life of the toothed belt. Moreover, the gear drive according to the present invention has improved belt life even under severe operating conditions such as high temperature and torsional vibration conditions. This improvement is most beneficial for small pulleys.

The present invention relates to a pulley for use in connection with a flexible drive belt as described in the "Miller" patent.

The term describing the features of the invention as used herein is defined in a patent of "Miller".

The present invention reduces the problem of the groove portion between the belt teeth by changing the pulley shape to increase the contact surface between the pulley top and the groove portion of the belt tooth. The pressure of the belt tooth groove is removed by supporting the belt tooth of the pulley groove. The pulley of this invention is a form which is not joined with a belt. Each pulley groove is formed by an arc connecting the threads of adjacent pulleys. When the belt travels around the pulley, the belt tooth presses against the pulley groove. Each pulley government has a longitudinal cross-sectional shape as described in the "Miller" patent, a portion of which consists of two circular arcs with curved centers spaced apart from each other. The curved centers are located on the same side of each arc with respect to the center of thread. The arcs of the threads are connected by almost straight or slightly curved line segments. The line segment forms the width of the thread of the pulley. According to the invention the surface ratio of the tooth width of the belt to the line segment is 20: 1-1: 1. This line length is 5% -100% and 6% -33% of the width of the belt on the belt on which the pulley is used.

The compression coupling and the surface contact ratio of the belt tooth with the pulley grooves act to reduce the groove wear of the belt, respectively. However, they reduce the belt's groove wear greater than the sum of their respective effects.

The invention will be more clearly understood from the following description set forth with reference to the accompanying drawings.

As shown in FIG. 1, the continuous belt 10 engages the drive pulley 11 and the driven pulley 12. The belt 10 has a tension member 13 formed by winding a continuous filament-like material several times. The tension member 13 carries up to the full working load imparted to the belt 10 and the maximum load in the belt design, the tension member 13 being almost inextensible. A detailed description of the principle of a general toothed belt and pulley system is described in the patents of "case" and "miller" mentioned above. The entire contents of the "case" and "miller" patents are each referenced herein. The belt also has a protective coating layer (not shown) and a support layer 14 formed on the entire surface of the belt. A thin layer of elastomeric material or other material (not shown) may be added between the coating layer and the tension member to promote adhesion in the groove region of the belt. The belt may be manufactured by any of several methods, but it is preferred to use the method described by "Double oil Skura". The entire contents of that patent are incorporated herein by reference. Another belt manufacturing method is described in the aforementioned "case" patent.

The pulleys 11 and 12 of FIG. 1 as shown in FIG. 2 have a body portion 20 having curved teeth 21 separated by curved surfaces 22. The thread 23, shown in longitudinal section, has an outer shape consisting of two arcs 24 and 25 with curved centers 26 and 27 away from the thread center line 28. The arcs 24 and 25 have uniform radii 29 and 30 with curved centers 26 and 27 spaced at equal intervals on both sides of the center line 28 of the teeth 21 on the same corresponding arc side. Both surface centers are in the teeth of the pulley. Circular arcs 24 and 25 are connected by line segments 31. Circular arc 24 extends from point A to point B, and circular arc 25 extends from point C to point D. The centers 26 and 27 are located at equal intervals from the tangent to the outer diameter of the pulley at the centerline 28 of the tooth and are located at the same radial interval from the center of the pulley. Line segment 31 is a portion of an arc having a radius drawn centered on an extension line of center line 28. The curved center of the line segment 31 may be located at the center line 28, ie within the pulley body. The curved center of the line segment 31 may also be located on an extension line of the center line 28 outside the body of the pulley. Line segment 31 is shown in a straight line but may be concave or convex with respect to the body of the pulley.

3 shows an enlarged partial longitudinal cross-sectional view of a second degree pulley superimposed on a drawing of a bonded pulley of the "Miller" patent. This figure highlights the difference in longitudinal profile of each of the pulley grooves and teeth. 3 shows the curved surface 22 of the present invention formed by the arc of radius 32 at the curved center 33. Arcs 24 and 25 which form partly the threads of the pulley of the present invention are formed by respective radii 29 and 30 having curved centers 26 and 27. The line segment of the present invention which forms the outermost part of the thread and connects the arcs 24 and 25 has the same length as the spacing between points B and C. The arc forming the curved surface 22 intersects the arcs 24 and 25 of the present invention at points A and D.

In contrast, a large bonded pulley according to the "Miller" patent has a curved surface 41 formed by an arc having a curved center 39 and a radius 40. Arcs 46 and 47, which form partly the threads of the pulley according to the "Miller" patent, are formed by radii 44 and 45 having curved centers 42 and 43, respectively. The line segments forming the outermost part of the thread and connecting arcs 46 and 47 have the same length as the spacing between points E and F. The arc forming the curved surface 41 intersects the arcs 46 and 47 at points G and H.

The line segment BC length of the present invention is larger than the length of the line segment EF of the thread of the pulley according to the "Miller" patent. The curved centers 26 and 27 of the present invention are located at the anode of the centerline 28, the spacing of which is greater than the spacing between the curved centers 42 and 43 of the thread of the pulley according to the patent of "Miller". Big. The hatched portion 48 represents an added portion present in the pulley groove and thread shape according to the invention as compared to the shape according to the "Miller" patent.

4 shows an enlarged, partial longitudinal cross-sectional view of the second degree pulley engaged with the belt according to the patent of "Miller" under no load. In its longitudinal section, each tooth 49 of the belt 50 consists of two arcs 51 and 52 of the same radius 53 and 54 intersecting at a point 55 on the centerline 34. have. The extension of arcs 51 and 52 extends to line 58. The curved centers 56 and 57 of the arcs 51 and 52 are located on either side of the centerline 34 away from their corresponding arc by 10% or less of the curved radius of the arcs 51 and 52.

The grooves between the teeth of adjacent pulleys in the present pulley have a depth less than the groove depth of the patented pulley of Miller and less than the depth of the teeth of the belt. This is specified in figure 4, in which the thread of the belt tooth is shown superimposed on the base of the pulley. However, this does not occur in practice and the belt teeth are distorted due to the contact with the pulley grooves. It is desirable that the pulley groove depth is 1% -15% smaller than the belt tooth depth.

In designing the drive mechanism according to the present invention, the distance between the belt teeth (the dotted line between points J and K in Fig. 4) with respect to the length of the line segment 31 (the width represented by the length of the line BC in Fig. 2) other than the above-mentioned standard The surface contact ratio of the length represented by the length of (59) is 20: 1-1 "1, Preferably 15: 1-3: 1 are required.

The cross-sectional shape of the curved surface 22 has a radius 32 much larger than the radius 29 and 30, and has a center 33 located outside the body of the pulley and on the center line 34. The curved centers 26, 27 and 33 are located in the same or slightly spaced circles 35 and 36 within the circle concentric with the circle connecting the outermost segment 31 of the thread. Circles 35 and 36 are radially inward from the circle at intervals equal to or less than 30% of the total tooth depth. The total depth is the radial spacing between the intersection of the line segment 31 and the centerline 28, the circle connecting the innermost point edge of the addendum 37 and the curved surface 22. The innermost point of the curved surface 22 is on the intersection of the circle formed by the radius 32 with the centerline 34, that is, the plaque circle 38.

The curved surface 22 is formed by an arc having a radius 32 drawn from the center 33 on the centerline 34. An arc forming curved surface 22 intersects an arc 24 on one side of the entire pulley groove shape and an arc 25 on the other side. The shape of the pulley groove from the intersection of the line segment 31 and the center line 28 to the corresponding intersection of the next adjacent tooth is repeated around the circumference of the pulley to form the same other pulleys and grooves.

The total depth of the pulley grooves is equal to the distance measured along the centerline 34 between the intersection points between the line 34 and the tooth source 37 and the basement source 38. As shown in FIG. 2, the total depth of the pulley grooves is the sum of the length of the radius 32 and the spacing d. Preferably, the total depth of the pulley groove is 15% smaller than the depth of the belt tooth engaged with the pulley groove. Therefore, the belt tooth can be press-fitted with the curved surface 22. In addition, the dimensional relationship between the pulley groove depth and the belt depth is as described in the "Miller" patent.

In designing the pulley groove and tooth shape, it is preferable that the arc forming the curved surface 22 gently intersects the arcs 24 and 25. However, it may be desirable to provide a connecting line to impart a gentle change from the arc forming curved surface 22 to arcs 24 and 25 forming part of the pulley thread. This connecting line is similar to line segment 31.

EXAMPLE

The following procedure was carried out to compare the performance of a transmission system having a pulley having a conventional dimension relation and a pulley having a novel dimension relation of the present invention. Various positive or simultaneous drive belt specimens were prepared by conventional methods using conventional furnaces well known in the art. All belts were formed from a neoprene rubber composition with a nylon fabric disposed on the belt teeth and had a tension member of glass fiber cords disposed on the tooth circle of the belt teeth. Once prepared, the belt specimens were tested dynamically with a toothed pulley of the appropriate dimensions and shape as described later.

Three transmission systems were tested and classified into A, B and C.

The transmission system A consists of a belt and a pulley made according to the patent of "Miller". These belts and pulleys are sold by "Uniroyal Incorporated."

The 18 belt specimens produced were measured in the longitudinal extension of the belt between the pulleys and then dimensioned. That is, the pitch between the belt teeth was 8.00 mm, the belt tooth width was 6.60 mm, and the distance between the belt teeth was 1.40 mm, the belt tooth depth was 3.43 mm, and the belt was 15 mm wide and the pitch length was 936 mm.

The pulley had a tooth depth of 3.61 mm and actually bonded with the belt tooth. As described in the "Miller" patent, the thread had a longitudinal cross-sectional shape consisting of two arcs connected by line segments. The line segment length was 0.28 mm. In that transmission system, the line segment is 4.2% of the width of the belt tooth. Transmission system B consists of the same transmission system as A, except that the belt tooth depth is increased from 0.31 mm (8.9%) to 3.73 mm. This is in accordance with the description of the "hawk". Seven belt specimens were prepared.

The transmission system C is constituted by the transmission system according to the present invention. The belt had the same dimensions as the belt in A. The pulley had a depth of 3.30 mm and the pulley groove had a radius of curvature of 2.69 mm. Line length was 0.51 mm.

Table 1 shows a comparison of the main dimensions (mm) of the transmission systems A, B and C and the compressions formed on the belt teeth.

TABLE 1

(Belt depth-Pulley depth)

Pulley depth

Each belt specimen was installed in a static load flexible tester with two pulley installations consisting of driving and driven pulleys each having an outer diameter of 54.86 mm. The drive pulley was operated at 350 rpm with a force of 11.35 kgf applied between the centers of the pulley axis. The experiment was performed at room temperature. The belt was tested and broken unless otherwise indicated. The elapsed time for each group of belt specimens to break is shown in Table 2.

[Table 2]

The experiment was repeated while maintaining the ambient temperature at 87.8 ℃, the results are shown in Table 3.

TABLE 3

The results in Tables 2 and 3 indicate that the pulley-belt combination C with the belt-pulley relationship of the present invention provides significantly improved belt life than A and B.

The only important variable in the comparative experiments was the relationship of the belt dimension to the pulley dimension. B had a belt tooth deeper than the depth of the pulley groove and C also had a belt tooth deeper than the length of the pulley groove. However, the segment length of the pulley at C was significantly larger than the segment length of the pulleys of A or B, and the pulleys of A and B had an inadequate line length that caused the belt to be subjected to excessive stress on the tension member. This excessive stress caused a breakage caused mainly by the wear of the belt between the trench bells and excessive wear in the area.

The line length in the pulley of C was long enough to distribute the load over a large area to reduce the stress in the area between the belt teeth. Thus, the wear of the belt area between the teeth of the belt was reduced and the belt life was significantly increased at room temperature and high temperature.

The pulleys described herein may be used in combination with other toothed belts other than those described in the patents of "case", "miller" and "hob". The longitudinal cross-sectional shape of each belt tooth may be trapezoidal, curved or wedge shaped or a combination or modified shape of these shapes. The belt may also have two sides of the tension member.

Claims (1)

In a toothed pulley 11 or 12 for use in conjunction with a toothed flexible belt, it consists of threads connected by curved portions 22 of the teeth 21 of the pulley, each thread being partly two circular arcs. Having a longitudinal cross-sectional shape consisting of (24, 25), the arcs having curved centers (26), (27) spaced apart from each other, the curved center of each arc being located on the same side of each arc with respect to the centerline (28) And the outermost part of the thread connects two arcs to form a line segment, wherein the length of the line segment is 6% -33% of the width of the belt tooth used for the pulley.

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