JP6121468B2 - Sprocket and sludge scraper - Google Patents

Description

  The present invention relates to a sprocket that transmits power by winding a chain around a plurality of teeth and the bottom of an outer periphery, and a sludge scraper equipped with the sprocket.

  As conventional sprockets, for example, those described in Patent Document 1 and Patent Document 2 below are known. In the sprocket of Patent Document 1, the tooth surface is formed in a tapered shape. Moreover, in the sprocket of Patent Document 2, the arc-shaped tooth surface that protrudes to the outside of the tooth is continuous with the arc-shaped tooth bottom that retreats to the inside of the tooth.

Japanese Patent Laying-Open No. 2014-169165 (see FIG. 4) Japanese Patent No. 4658429 (see FIG. 1)

  In conventional sprockets, when the chain is extended and used for many years and its tension is lowered, the chain and sprocket do not mesh well, and the chain contact part of the chain slips over the teeth, so-called `` tooth skipping '' may occur. there were. If tooth skipping occurs, power transmission from the chain to the sprocket or power transmission from the sprocket to the chain will be hindered.

  An object of the present invention is to provide a sprocket in which tooth skipping is unlikely to occur.

First characterizing feature of the sprocket of the present invention comprises the outer periphery and a plurality of teeth and tooth bottom alternately, the sprocket and the tooth surface and the cylindrical contact portion of the chain of the a rotationally driven teeth are in contact, the teeth a substantially trapezoidal shape with the tooth crest and the tooth surface on the left and right through the vicinity of the intersection or intersection point between the tooth surface and the pitch circle of the teeth, and and the cylindrical contact portion of the chain during rotation drive start tangential contact with the tooth bottom portion in contact, or, the curved portion than the straight line connecting the neighborhood and the tooth bottom portion of the intersection or intersection point between the tooth surface and the pitch circle of the teeth to retire inside the toothed The curved surface portion is provided continuously to the tooth bottom portion .

[Action and effect]
By providing a curved surface as in this configuration, contact between the tooth surface of the tooth and the cylindrical contact portion of the chain is improved. Is done effectively.

  The second characteristic configuration is that the curved surface portion has an arc shape.

[Action and effect]
By making the curved surface portion into an arc shape as in this configuration, the driving force can be transmitted to the chain without changing the contact force of the cylindrical contact portion of the chain on the curved surface portion.

  A third characteristic configuration is that the radius of curvature of the curved surface portion is greater than 1 and less than or equal to 3 times the radius of the cylindrical contact portion of the chain.

[Action and effect]
According to this configuration, the contact force of the cylindrical contact portion of the chain can be increased (about 1.2 times) compared to a conventional sprocket having a tooth surface formed in a tapered shape.

  A fourth characteristic configuration includes a left circular arc portion and a right circular arc portion that retreat inside the tooth bottom as the tooth bottom portion on each of the left and right sides of the tooth bottom, and a central arc portion that projects outside the tooth bottom. Is provided between the left arc portion and the right arc portion.

[Action and effect]
According to this configuration, even if the chain is elongated due to long-term use, the column contact portion of the chain can move smoothly along the pitch circle when the sprocket is rotated in the reverse direction.

It is a top view of the sprocket of the present invention. It is a partially expanded plan view of the sprocket of the present invention. It is the whole longitudinal section of sewage treatment equipment provided with the sludge scraper of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the sprocket 1 of the present embodiment includes a plurality of teeth 2 and a tooth bottom 10, and these teeth 2 and the tooth bottom 10 are alternately arranged along the outer periphery of the sprocket.

  The tooth 2 includes a right tooth surface 3 and a left tooth surface 6 that are smooth curved surfaces, and a tooth tip surface 9 that is a flat surface, and has a symmetrical shape in plan view.

  A left arc portion 11 and a right arc portion 12 that are retracted in an arc shape are provided on the left and right sides of the tooth base 10 inside the tooth base 10 (see the double-headed arrow in FIG. 2). The left arc portion 11 and the right arc portion 12 constitute a tooth bottom portion that comes into contact with the column contact portion R of the chain at the start of rotational driving. Further, the tooth bottom 10 is provided with a central arc portion 13 that gently protrudes in an arc shape on the outer side (see the double-headed arrow in FIG. 2) between the left arc portion 11 and the right arc portion 12. It has a symmetrical shape in view. The central arc portion 13 is preferably an arcuate curved surface concentric with the pitch circle PC. Further, the central arc portion 13 is not necessarily provided, and the tooth bottom 10 may be configured only by a curved surface that retreats in an arc shape toward the rotation center side of the sprocket 1.

  When the sprocket 1 of this embodiment is used by rotating it clockwise (clockwise in FIG. 1), the cylindrical contact portion R of the chain is located on the portion extending from the right arc surface 12 of the tooth base 10 to the right tooth surface 3 of the tooth 2. When the chain is locked and rotated counterclockwise (counterclockwise in FIG. 1), the cylindrical contact portion R of the chain is locked to the portion extending from the left arc surface 11 of the tooth base 10 to the left tooth surface 6 of the tooth 2. Is done.

  As shown in FIG. 2, the inner side of the tooth 2 from the tangent line T1 passing through the intersection C1 of the right tooth surface 3 and the pitch circle PC and in contact with the right arc portion 12 of the tooth base 10 (refer to the bidirectional arrow in FIG. The right tooth surface 3 of the tooth is provided with the right curved surface portion 5 that is retreated. The right curved surface portion 5 smoothly continues to the right arc portion 12 of the tooth bottom 10.

  The right tooth surface 3 includes an arc-shaped right curved surface 4 that protrudes from the intersection C1 to the tip surface 9 to the outside of the tooth 2 (see the double-headed arrow in FIG. 2), and the right curved surface 4 and the right curved surface portion 5 are provided. Smoothly continuous. In the present embodiment, the intersection C1 and the starting point of the right curved surface 4 (starting point of rounding of the corners) coincide with each other, so that power transmission and chain detachment become smoother.

  As shown in FIG. 2, the right curved surface portion 5 is preferably arcuate. Further, the radius of curvature r2 of the right curved surface portion 5 is desirably larger than 1 times and not larger than 3 times the radius r4 of the cylindrical contact portion R of the chain, and more desirably not smaller than 2 times and not larger than 3 times.

The curvature radius r1 of the right curved surface 4, the curvature radius r2 of the right curved surface portion 5, and the curvature radius r3 of the right circular arc portion 12 can be set based on, for example, the following calculation formulas 1 to 3. In the formula, d ₁ is the maximum outer diameter of the cylindrical contact portion R of the chain, and z is the number of teeth.
Formula _{1: r1 = (1.005d 1 +0.076} ) / 2
Formula 2: r2 = 1.3025d ₁ +0.038
Formula 3: r3 = d ₁ [0.8 cos (18 ° -56 ° / z) +1.4 cos (17 ° -64 ° / z) −1.3025] −0.038

  In addition, you may comprise a tooth surface using at least any one of the above-mentioned calculation formulas 1-3, and it is more preferable to comprise a tooth surface using Formula 1 and Formula 2.

  The left tooth surface 6 of the tooth has the same configuration as the right tooth surface 3. That is, the left curved surface portion 8 that passes through the intersection C2 between the left tooth surface 6 and the pitch circle PC and is retracted to the inside of the tooth 2 from the tangent line T2 that is in contact with the left arc portion 11 of the tooth base 10 is Surface 6 is provided. The left curved surface portion 8 smoothly continues to the left arc portion 11 of the tooth bottom 10. The left tooth surface 6 includes an arcuate left curved surface 7 projecting from the tooth 2 to the outside of the tooth 2 from the intersection C to the tooth tip surface 9, and the left curved surface 7 and the left curved surface portion 8 are smoothly continuous. Also, the intersection C2 and the start point of the left curved surface 7 (start point of rounding corners) coincide.

  By providing the right curved surface portion 5 and the left curved surface portion 8 as described above, the contact between the right tooth surface 3 and the left tooth surface 6 and the column contact portion R of the chain is improved. Even if extended, tooth skipping hardly occurs and power transmission is effectively performed. Furthermore, by providing the right curved surface portion 5 and the left curved surface portion 8, it becomes easier to perform a machining operation (for example, end milling or the like) than a conventional sprocket, and the manufacturing cost can be suppressed.

  The above-described sprocket 1 can be applied to, for example, both a driving sprocket and a driven sprocket of a sludge scraper. Hereinafter, an example in which the above-described sprocket 1 is applied to a driving sprocket and a driven sprocket of a sludge scraper will be described.

  FIG. 3 shows a longitudinal section of the sedimentation basin 20 in the sewage treatment facility, where a sludge scraper 21 and a scum skimmer 23 are installed, and the sludge scraper 21 is provided with a drive structure for an endless chain 24.

  The sludge scraper 21 has a pair of left and right endless chains 24 as endless rotating bodies to which a sludge scraping tool 22 is attached at intervals in the rotational direction, and drive rotation that rotates about a horizontal axis (rotation center) X. A driving sprocket 1a as a body, a driven sprocket 1b as a driven rotating body, and a driving device 25 that drives and rotates the driving sprocket 1a.

  The endless chain 24 is rotatably wound around the driving sprocket 1a and the three driven sprockets 1b. When the driving device 25 rotationally drives the driving sprocket 1a, the endless chain 24 rotates in the clockwise direction on the sheet of FIG. As a result, the sludge that has settled near the bottom surface 26 of the sedimentation basin 20 is provided at the bottom of the sedimentation basin 20 while the scum floating near the water surface WL of the sedimentation basin 20 is scraped toward the scum skimmer 23 side. Can be raked in.

[Other Embodiments]
1. The tangent line T described above does not necessarily pass through the intersection points C1 and C2, and it passes through the vicinity of the intersection points C1 and C2 as long as the same action and effect as the above-described action and effect can be exhibited. May be.
2. The shape of the tooth bottom portion of the tooth bottom 10 described above is not necessarily an arc shape, and may be another curved line or a straight line shape. In addition, when the shape of the root portion is a straight line, the curved surface portion is retracted inside the tooth 2 from the intersection of the tooth surface of the tooth and the pitch circle or a straight line connecting the vicinity of the intersection and the root portion. It becomes the composition to do. Although not shown, for example, when each of the left and right tooth bottom portions of the tooth bottom 10 in the above-described embodiment is linear, the intersection C1 between the right tooth surface 3 and the pitch circle PC and the right tooth bottom of the tooth bottom 10 are illustrated. The right curved surface part 5 is retracted inside the tooth 2 from the straight line connecting the parts, and the tooth 2 is located more than the straight line connecting the intersection C2 between the left tooth surface 6 and the pitch circle PC and the left tooth bottom part of the tooth base 10. The left curved surface portion 8 retreats inside.
3. The shape of each of the right curved surface 4 and the left curved surface 7 does not necessarily need to be an arc shape, as long as the cylindrical contact portion R of the chain is easy to come off from the tooth bottom 10 after finishing the power transmission. Other curves may be used, or a straight line may be used.
4). The above-mentioned tooth tip surface 9 does not necessarily have to be a flat surface, and may be an arcuate curved surface concentric with the pitch circle PC.
5). The shape of the above-mentioned central arc portion 13 does not necessarily have an arc shape, and when the cylindrical contact portion R slides in the tooth bottom, the axis of the cylindrical contact portion R does not enter the center side of the pitch circle PC greatly. Any shape is acceptable.
6). For the above-described cylindrical contact portion R, a rotatable roller may be used.

  The present invention can be applied to a sprocket that winds a chain and transmits power.

1 sprocket 1a driving sprocket 1b driven sprocket 2 tooth 3 right tooth surface 4 right curved surface 5 right curved surface portion (curved surface portion)
6 Left tooth surface 7 Left curved surface 8 Left curved surface (curved surface)
9 Tooth tip surface 10 Tooth bottom 11 Left circular arc part (tooth bottom part)
12 Right arc (tooth root)
13 Central arc portion 20 Sedimentation basin 21 Sludge scraper 22 Sludge scraper 23 Scum skimmer 24 Endless chain 25 Drive device 26 Bottom surface 27 Discharge groove PC Pitch circle C1, C2 Intersection T1, T2 Tangent R Chain contact portion of chain

Claims (5)

In a sprocket where a plurality of teeth and a tooth bottom are alternately provided on the outer periphery and the tooth surface of the teeth and the cylindrical contact portion of the chain come into contact with each other when rotated ,
The tooth has a substantially trapezoidal shape including a tooth tip surface and the tooth surfaces on the left and right sides thereof ,
Through the vicinity of the intersection or intersection point between the tooth surface and the pitch circle of the teeth, and the tangent in contact with the tooth bottom portion in contact with the cylindrical contact portion of the chain during rotation drive start or tooth surface and the pitch circle of the teeth wherein the straight line connecting the tooth bottom portion includes a curved portion to retire to the inside of the tooth on the tooth surface, provided curved surface portion is continuous with the tooth bottom portion and the vicinity of the intersection or intersection point of the sprocket, characterized in that there.   The sprocket according to claim 1, wherein the curved surface portion has an arc shape.   3. The sprocket according to claim 1, wherein a radius of curvature of the curved surface portion is greater than one and less than or equal to three times a radius of a cylindrical contact portion of the chain.   Each of the left and right sides of the root includes a left arc portion and a right arc portion that retreat inside the root as the root portion, and a central arc portion that protrudes outside the root is the left arc portion. The sprocket according to any one of claims 1 to 3, wherein the sprocket is provided between the right arc portion and the right arc portion.   A sludge scraping machine using the sprocket according to any one of claims 1 to 4 as a drive sprocket or a driven sprocket.

Images