JP2014159818A - Gear and drive transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce thrust force to a toothed belt wound on a toothed pulley.SOLUTION: A toothed belt 4A includes a tooth 41 having a torsion angle β1, and a tooth 42 having a torsion angle β2. The torsion angles β1 and β2 have torsional directions opposite to each other when observed in a direction ζr directing to dedenda from addenda of the teeth 41 and 42. Thus when the toothed belt 4A is wound on a toothed pulley engaged with the toothed belt 4A, thrust force received by the tooth 41 and thrust force received by the tooth 42 act in the directions opposite to each other. Thus the thrust force received by the toothed belt 4A is reduced.

Description

  The present invention relates to a gear and a drive transmission device. Here, the gear includes not only a so-called rack (including a helical rack) and a gear (including a helical gear) but also a toothed belt and a toothed pulley used by meshing with a toothed belt. It is a concept.

  The toothed belt provided in the drive transmission device is used in combination with a toothed pulley for driving the toothed belt. A toothed pulley is used as a timing pulley. As a drive transmission device using a general-purpose toothed belt and a toothed pulley, there is a case where a ring-shaped toothed belt is driven by a plurality of toothed pulleys.

  Depending on the attachment state of the toothed pulley, the tensile force (hereinafter referred to as tension) applied to the toothed belt differs at both ends in the width direction of the toothed belt. Thus, when the toothed belt is driven, the toothed belt receives a so-called thrust force in the width direction perpendicular to the driving direction due to the relationship between the balance of tension and the driving direction. This thrust force causes the toothed belt to be detached from the toothed pulley.

Japanese Patent No. 4010551

  Conventionally, the tooth shape of the toothed belt has been devised. For example, the toothed belt of Patent Document 1 is intended to reduce noise and vibration.

  Furthermore, the shape of the helical tooth (hereinafter also referred to as “oblique tooth”) of Patent Document 1 has a component in which the resultant force of the deviation of the driving direction of the toothed belt and the width direction is directed to the direction of the oblique tooth. In this case, the toothed belt is displaced, so that the toothed belt cannot be prevented from being displaced.

  On the other hand, as a method for preventing the deviation of the toothed belt, there is also a method of devising the shape of the toothed pulley. For example, if a toothed pulley provided with a flange is used, it becomes difficult for the toothed belt to come off the toothed pulley.

  However, if a toothed pulley with a flange is used without suppressing the generation of thrust force, the toothed belt moves in the width direction and comes into contact with the flange. This leads to a problem that the toothed belt is scraped.

  Such thrust force is not only applied to a drive transmission device using a toothed belt and a toothed pulley, but also when gears employing bevel teeth, for example, bevel gears or a combination of bevel gears and a bevel rack. Also occurs.

  The present invention has been made to solve the above-described problems, and reduces or prevents the application of force in the direction orthogonal to both the direction in which the gear is driven and the direction in which the gears mesh with each other. The purpose is to do.

  The gear according to the present invention includes a plurality of teeth. Here, the gear is a concept including not only a so-called rack (including an inclined gear rack) and gear (including an inclined gear) but also a toothed belt and a toothed pulley used by meshing with the toothed belt. is there.

  The first aspect of the gear according to the present invention is such that the gears are driven in the same second direction and are opposite to each other when viewed along the first direction from the end of the tooth to the root. It has the 1st tooth surface and the 2nd tooth surface which exhibit a twist angle. The first tooth surface and the second tooth surface are adjacent to each other in the first direction or the second direction, and are orthogonal to both the first direction and the second direction. It is characterized by not adjoining in the direction.

  The 2nd aspect of the gearwheel concerning this invention is the 1st aspect, Comprising: The said 1st tooth surface and the said 2nd tooth surface are alternately arrange | positioned in the same side surface.

  The 3rd aspect of the gearwheel concerning this invention is the 2nd aspect, Comprising: The said tooth | gear is provided with the tooth | gear which exhibits both the said 1st tooth surface and the said 2nd tooth surface.

  4th aspect of the gearwheel concerning this invention is the 1st aspect, Comprising: The said tooth | gear WHEREIN: The 1st tooth | gear which exhibits the said 1st tooth surface, and 2nd which exhibits the said 2nd tooth surface It is divided into teeth.

  The 5th aspect of the gearwheel concerning this invention is the 4th aspect, Comprising: The said 1st tooth | gear and the said 2nd tooth | gear are alternately arrange | positioned in the same side surface.

  A sixth aspect of the gear according to the present invention is the fourth aspect thereof, wherein the first surface in which the first teeth are arranged in the second direction and the second teeth are the first aspect. The first surface further includes a second surface that is arranged in two directions and is opposed to the first surface in the first direction.

  A first aspect of the drive transmission device according to the present invention includes a toothed belt that is the third aspect of the gear according to the present invention and a toothed pulley that is the fourth aspect of the gear according to the present invention. The toothed belt and the toothed pulley mesh with each other.

  A second aspect of the drive transmission device according to the present invention includes a toothed belt that is the fourth aspect of the gear according to the present invention and a toothed pulley that is the third aspect of the gear according to the present invention. The toothed belt and the toothed pulley mesh with each other.

  According to a third aspect of the drive transmission device of the present invention, there is provided a toothed belt that is the sixth aspect of the gear according to the present invention, a toothed pulley that meshes from an inner peripheral side of the toothed belt, and the toothed belt. And a toothed pulley that meshes from the outer peripheral side of the belt.

  The 4th aspect of the drive transmission device concerning this invention is the 3rd aspect, Comprising: A pair of said toothed pulley pinches | interposes the said toothed belt.

  A fifth aspect of the drive transmission device according to the present invention is the third aspect, wherein two or more toothed pulleys that mesh with the toothed belt from the inner peripheral side are provided, and The toothed pulley that meshes with the toothed belt functions as a tensioner.

  A sixth aspect of the drive transmission device according to the present invention is any one of the first to fifth aspects, wherein the toothed belt is linear and both ends thereof are fixed, and both ends of the toothed belt are fixed. The toothed pulley can move between them.

  According to the gear according to the present invention, it is possible to reduce or cancel the application of force in the direction in which the gear is driven and the direction in which the meshing gears are connected to each other.

  According to the drive transmission device according to the present invention, the toothed belt is unlikely to come off the toothed pulley.

1 is a perspective view showing a configuration of a toothed belt described in Embodiment 1. FIG. 3 is a plan view showing a configuration of a toothed belt described in Embodiment 1. FIG. 3 is a plan view showing a configuration of a toothed belt described in Embodiment 1. FIG. FIG. 3 is a perspective view illustrating a configuration of a toothed pulley described in the first embodiment. It is a top view which shows the meshing of the toothed belt demonstrated in Embodiment 1, and a toothed pulley. It is a perspective view which shows the structure of the toothed belt demonstrated in Embodiment 2. FIG. 6 is a plan view showing a configuration of a toothed belt described in Embodiment 2. FIG. 6 is a plan view showing a configuration of a toothed belt described in Embodiment 2. FIG. It is a perspective view which shows the structure of the toothed pulley demonstrated in Embodiment 2. FIG. It is a top view which shows the meshing of the toothed belt demonstrated in Embodiment 2, and a toothed pulley. It is a perspective view which shows the combination of a toothed belt and a toothed pulley in a prior art. It is a perspective view which shows the combination of a toothed belt and a toothed pulley in a prior art. It is a perspective view which shows the combination of the toothed belt and toothed pulley which Embodiment 1 and Embodiment 2 can apply. It is a perspective view which shows the combination of the toothed belt and toothed pulley which Embodiment 1 and Embodiment 2 can apply. It is a perspective view which shows partially the structure of the toothed belt demonstrated in Embodiment 3. FIG. 6 is a plan view showing a configuration of a toothed belt described in Embodiment 3. FIG. 6 is a plan view showing a configuration of a toothed belt described in Embodiment 3. FIG. 6 is a plan view showing a configuration of a toothed belt described in Embodiment 3. FIG. It is a perspective view which shows the combination of the toothed belt and toothed pulley which Embodiment 3 can apply. It is a perspective view which shows the combination of the toothed belt and toothed pulley which Embodiment 3 can apply. It is a perspective view which shows the combination of the toothed belt and toothed pulley which Embodiment 3 can apply. It is a perspective view which shows the combination of the toothed belt and toothed pulley which Embodiment 3 can apply.

Embodiment 1 FIG.
FIG. 1 is a perspective view partially showing the configuration of a toothed belt 4A described in the first embodiment. The toothed belt 4A is formed, for example, in a ring shape, but the perspective view shows a flat portion of the toothed belt 4A. In this portion, the toothed belt 4A can be grasped as a rack.

  On the other hand, as described later, when a part of the toothed belt 4A is wound around a toothed pulley that functions as an external gear, the toothed belt 4A can be grasped as a part of the internal gear. .

  In other words, it can be understood that the toothed belt 4A has a configuration in which the rack and a part of the internal gear are connected in the driving direction.

  The toothed belt 4A is driven in the direction ξr. Since FIG. 1 shows a portion where the toothed belt 4A is flat, the direction ξr is also shown as a linear direction.

  The toothed belt 4 </ b> A has teeth 41 and 42. The teeth 41 and 42 protrude with respect to the root 40. The direction ζr when the tooth root is viewed from the end of the teeth 41 and 42 is not parallel to the direction ξr. In the illustration of FIG. 1, the directions ξr and ζr are orthogonal to each other.

  The tooth 41 has a tooth crest 41c and a pair of tooth surfaces 41a. In FIG. 1, the tooth tip 41t of the tooth 41 is shown as a boundary between the tooth crest 41c and the tooth surface 41a. However, this is for convenience of illustration, and it means that the tooth tip 41t coincides with the boundary between the tooth top 41c and the tooth surface 41a because the tooth top 41c and the tooth surface 41a are flat. do not do.

  Like the tooth 41, the tooth 42 has a tooth crest 42c and a pair of tooth surfaces 42a, and a tooth tip 42t appears.

In FIG. 1, the twist angle is illustrated for the tooth tip. this is,
-As will be described later, what is important in this embodiment and the following embodiments is not the magnitude of the torsion angle itself but the direction in which the tooth surface is twisted,
・ In the structure of normal gear teeth, the direction of the torsion angle of the tooth surface and the torsion angle of the tooth tip should not conflict.
by.

  Specifically, in FIG. 1, the torsion angles of the tooth surfaces 41a and 42a are represented as the torsion angle β1 of the tooth tip 41t and the torsion angle β2 of the tooth tip 42t, respectively.

  Here, the standard of the twist angle is the direction ηr, which is indicated by a two-dot chain line. The direction ηr is orthogonal to both the directions ξr and ζr. The direction in which the tooth tips 41t and 42t extend is indicated by a one-dot chain line.

  However, the twist angle is grasped along the direction ζr for a certain tooth. Here, the twist angle β1 of the tooth surface 41a is counterclockwise, and the twist angle β2 of the tooth surface 42a is clockwise.

  Both FIG. 2 and FIG. 3 are plan views showing a portion that can be grasped as a rack in the configuration of the toothed belt 4A. FIG. 2 is a plan view of the portion as viewed along the direction ζr. FIG. 3 is a plan view of the portion as seen along the direction opposite to the direction ηr.

  In FIG. 2, the tooth surfaces 41 a and 42 a are illustrated as being flat surfaces. Therefore, the torsion angles β1 and β2 are each based on the direction ξr (the reference is indicated by a two-dot chain line), and the directions of the components orthogonal to the direction ζr among the normal lines of the tooth surfaces 41a and 42a (both are one-dot chain lines). It is expressed as an angle formed by This is because the directions ξr and ηr are orthogonal to each other.

  In plan view along the direction ζr, the tooth surface 41a expands along the direction ξr, for example, with a width 41d or a width 41e. Similarly, the tooth surface 42a expands along the direction ξr, for example, with a width 42d or a width 42e. The tooth crests 41c and 42c expand along the direction ξr with, for example, widths 41L and 42L, respectively.

  If the cross-sectional shape of the tooth 41 viewed along the direction ηr is an isosceles trapezoid, the widths 41d and 41e are equal to each other. If the cross-sectional shape of the tooth 42 viewed along the direction ηr is an isosceles trapezoid, the widths 42d and 42e are equal to each other. The widths 41L and 42L may be equal to or different from each other.

  From the above, it can be grasped that the toothed belt 4A has the following [Feature 1].

[Feature 1]
(1a) The toothed belt 4A has tooth surfaces 41a and 42a;
(1b) The tooth surfaces 41a and 42a are driven in the same direction ξr when viewed along the direction ζr from the end of the tooth 41 (or the tooth 42) toward the tooth root;
(1c) When viewed along the direction ζr from the end of the tooth 41 (or tooth 42) toward the tooth root, the tooth surfaces 41a and 42a exhibit twist angles β1 and β2 opposite to each other;
(1d) The tooth surfaces 41a and 42a are adjacent in the direction ξr.

  It should be noted in the feature (1b) that the driving direction of the tooth surfaces 41a and 42a is determined by paying attention to a certain tooth and looking along the direction ζr from the tooth end to the tooth root. It is. For example, in a normal toothed belt, a pair of teeth arranged so that the protruding directions from the tooth bottom face each other are driven in the same direction when viewed along the direction from the end of one tooth toward the root of the tooth. (This point will be described later again with reference to FIG. 5). Therefore, even if the normal inclined belt satisfies the feature (1c), it does not satisfy the feature (1b).

  With such a feature, particularly the feature (1c), the above-described thrust force can be reduced. That is, when the toothed belt 4A is driven in the direction ξr using a gear meshing with the teeth 41 and 42, the direction ξr and the direction connecting the gear and the toothed belt 4A (almost parallel to the direction ζr) The force in the orthogonal direction ηr is less likely to be applied to the toothed belt 4A. This is because the thrust force by the tooth surface 41a and the thrust force by the tooth surface 42a are in opposite directions.

  Since the tooth 41 has a pair of tooth surfaces 41a and the tooth 42 has a pair of tooth surfaces 42a, it can be grasped that the toothed belt 4A has the following [Feature 2].

  [Characteristic 2] The teeth of the toothed belt 4A are classified into a tooth 41 having a tooth surface 41a whose twist direction is counterclockwise and a tooth 42 having a tooth surface 42a whose twist direction is clockwise. The

  Furthermore, it can be grasped as a feature that the teeth 41 and 42 are alternately arranged along the direction ξr.

  The toothed belt 4A can be grasped as a left-twisted rack (hereinafter referred to as a “left rack”) or a left-twisted internal gear when viewed from the tooth 41. (Hereinafter referred to as “right rack”) or a right-handed internal gear. Accordingly, the toothed pulley that drives the toothed belt 4A includes an external gear (hereinafter referred to as “right pinion”) that is a normal right-handed helical gear and an external gear (hereinafter “left-handed”) that is a left-handed helical gear. "Pinion") cannot be adopted.

  FIG. 4 is a perspective view partially showing a toothed pulley 5A that meshes with the toothed belt 4A to drive the toothed belt 4A. The toothed pulley 5A includes teeth 53 and 54 and can be grasped as an external gear.

  The teeth 53 and 54 protrude with respect to the root 50. The direction ζp of the tooth 53, 54 viewed from the end of the tooth is non-parallel to the direction ξp in which the toothed pulley 5A rotates. In the illustration of FIG. 4, the direction ζp goes to the center (not shown) of the toothed pulley 5A, and the directions ξp and ζp are orthogonal to each other.

  The teeth 53 and 54 have tooth crests 53c and 54c, respectively. The teeth 53 and 54 further have a pair of tooth surfaces 55a and 55b. In FIG. 4, the tooth tip 55at is shown as a boundary between the tooth top 53c and the tooth surface 55a, or as a boundary between the tooth top 54c and the tooth surface 55a. Similarly, the tooth tip 55bt is shown as the boundary between the tooth crest 53c and the tooth surface 55b or as the boundary between the tooth crest 54c and the tooth surface 55b. However, these are illustrations for convenience, and do not necessarily mean that the tooth crests 53c and 54c and the tooth surfaces 55a and 55b are flat.

  The tooth 53 has a tooth surface 55a on the side proceeding with respect to the direction ξp and a tooth surface 55b on the following side. The tooth 54 has a tooth surface 55b on the side proceeding with respect to the direction ξp and a tooth surface 55a on the following side.

  In FIG. 4, as in FIG. 1, the torsion angles of the tooth surfaces 55a and 55b are expressed as the torsion angle β3 of the tooth tip 55at and the torsion angle β4 of the tooth tip 55bt, respectively.

  Here, the standard of the twist angle is the direction ηp, which is indicated by a two-dot chain line. The direction ηp is orthogonal to both the directions ξp and ζp. The direction in which the tooth tips 55at and 55bt extend is indicated by a one-dot chain line.

  However, the twist angle is grasped along the direction ζp for a certain tooth. The direction ζp is substantially opposite to the direction in which each tooth protrudes. Unlike the rack, the direction ζp is different for each tooth in the external gear.

  Here, the twist angle β3 of the tooth surface 55a is counterclockwise, and the twist angle β4 of the tooth surface 55b is clockwise.

  From the above, it can be understood that the toothed pulley 5A includes the following [Feature 3], similar to the above [Feature 1].

[Feature 3]
(3a) The toothed pulley 5A has tooth surfaces 55a and 55b;
(3b) The tooth surfaces 55a and 55b are both driven in the same direction ξp when viewed along the direction ζp from the end of the tooth 53 (or tooth 54) toward the tooth root;
(3c) When viewed along the direction ζp from the end of the tooth 53 (or tooth 54) toward the tooth root, the tooth surfaces 55a and 55b exhibit twist angles β3 and β4 opposite to each other;
(3d) The tooth surfaces 55a and 55b are adjacent in the direction ξp.

  It should be noted in the feature (3b) that the driving direction of the tooth surfaces 55a and 55b is determined by focusing on a certain tooth and looking along the direction ζp from the end of the tooth toward the root. It is. For example, in a normal external gear, a pair of teeth arranged with the rotation shaft interposed therebetween is not driven in the same direction as viewed along the direction from the end of one of the teeth toward the root. Therefore, even if the normal inclined gear satisfies the characteristic (3c), it does not satisfy the characteristic (3b).

  In addition, it can be said that all of the teeth 53 and 54 included in the toothed pulley 5A have tooth surfaces 55a and 55b.

  In general, the left pinion and the right rack mesh with each other, and the right pinion and the left rack mesh with each other. In view of this, the toothed pulley 5A and the toothed belt 4A are engaged with each other by setting the twist angle β2 and the twist angle β3 to the same degree and setting the twist angle β1 and the twist angle β4 to the same degree. . More specifically, the toothed belt 4A and the toothed pulley 5A can be engaged with each other so that the tooth surface 55a and the tooth surface 55b are in contact with the tooth surface 41a and the tooth surface 42a, respectively. Needless to say, the pitch is equalized between the toothed pulley 5A and the toothed belt 4A.

  [Characteristic 3], particularly the characteristic (3c), can reduce the above-described thrust force. That is, by engaging the toothed belt 4A and the toothed pulley 5A so that the tooth surface 55a contacts the tooth surface 41a and the tooth surface 55b contacts the tooth surface 42a, the toothed belt 4A is moved in the direction ξr. Can be driven. As described above, the force in the direction ηr is not easily applied to the toothed belt 4A.

  FIG. 5 is a plan view showing a state in which the toothed belt 4A and the toothed pulley 5A are engaged with each other. The plane is a plane viewed along the direction ηr when viewed from the toothed belt 4A, and is a plane viewed along the direction opposite to the direction ηp when viewed from the toothed pulley 5A.

  In FIG. 5, the directions ξr and ζr are different between the left side and the right side of the drawing. This is because the toothed belt 4A meshes with the toothed pulley 5A and makes a U-turn. The directions ξr and ζr on the left side of the drawing indicate the portion of the toothed belt 4A toward the toothed pulley 5A that is grasped as a rack. The directions ξr and ζr on the right side of the drawing indicate the portion of the toothed belt 4A that is separated from the toothed pulley 5A and is grasped as a rack.

  As described above with respect to (1b), when viewed in the direction ζr for one tooth, the direction ξr for the toothed belt 4A toward the toothed pulley 5A is the same as that for the toothed belt 4A away from the toothed pulley 5A. The direction is opposite to the direction ξr.

  As described above, the thrust force is reduced or offset, and the toothed belt 4A is unlikely to be detached from the toothed pulley 5A.

  Since both the teeth 53 and 54 have the tooth surfaces 55a and 55b, it can be understood that the toothed pulley 5A has the following [Feature 4].

  [Feature 4] The tooth surfaces 55a and 55b satisfying the above [Feature 3] are alternately arranged in the root 50.

  Here, since the toothed pulley 5 is an external gear and has a substantially cylindrical shape, the tooth bottom 50 can be grasped only as the outer side, not the same side, that is, both the outer side and the inner side.

  The teeth 53 and 54 have different tooth thicknesses depending on the direction ηp. With reference to FIG. 4, the tooth thickness of the tooth 53 becomes thicker and the tooth thickness of the tooth 54 becomes thinner toward the direction ηp.

  Therefore, the teeth 53 and 54 can be grasped as being alternately arranged along the direction ξp so that the tooth shape itself is the same and the direction in which the tooth thickness increases is different.

  However, as indicated by [Feature 4], the tooth thickness itself is not necessarily the premise for obtaining the operation of this embodiment. The tooth 53 only needs to have tooth surfaces 55a and 55b, and the crest 53c of the tooth is not trapezoidal but may be V-shaped opening toward the direction ηp. Similarly, the tooth 54 only needs to have tooth surfaces 55a and 55b, and the tooth crest 54c is not trapezoidal but may be V-shaped so as to open in a direction opposite to the direction ηp.

Embodiment 2. FIG.
In the first embodiment, since the toothed belt 4A and the toothed pulley 5A mesh with each other, they mesh even if the configurations of the respective teeth are changed. And even with such engagement, the thrust force can be reduced or offset.

  FIG. 6 is a perspective view partially showing the configuration of the toothed belt 4B described in the second embodiment. In the perspective view, a flattened portion of the toothed belt 4B is shown. In this part, similarly to the toothed belt 4A, the toothed belt 4B can be grasped as a rack. Similarly to the toothed belt 4A, the toothed belt 4B can also be understood as having a configuration in which the rack and a part of the internal gear are connected in the driving direction.

  The toothed belt 4B is driven in the direction ξr. Similar to FIG. 1, the direction ξr is also shown as a linear direction in FIG. 6.

  The toothed belt 4 </ b> B has teeth 43 and 44. The teeth 43 and 44 protrude with respect to the root 40. The direction ζr of the tooth 43, 44 viewed from the end of the tooth is non-parallel to the direction ξr in which the toothed belt 4B is driven. In the illustration of FIG. 6, the directions ξr and ζr are orthogonal to each other.

  The teeth 43 and 44 have tooth crests 43c and 44c, respectively. Each of the teeth 43 and 44 further has a pair of tooth surfaces 45a and 45b. In FIG. 6, the tooth tip 43at is shown as a boundary between the tooth top 43c and the tooth surface 45a, or as a boundary between the tooth top 44c and the tooth surface 45a. Similarly, the tooth tip 43bt is shown as a boundary between the tooth crest 43c and the tooth surface 45b or as a boundary between the tooth crest 44c and the tooth surface 45b. However, these are illustrations for convenience, and do not necessarily mean that the tooth crests 43c and 44c and the tooth surfaces 45a and 45b are flat.

  The tooth 43 has a tooth surface 45b on the side proceeding with respect to the direction ξr and a tooth surface 45a on the following side. The tooth 44 has a tooth surface 45a on the side proceeding with respect to the direction ξr and a tooth surface 45b on the following side.

  In FIG. 6, as in FIG. 1, the torsion angles of the tooth surfaces 45a and 45b are represented as the torsion angle β5 of the tooth tip 45at and the torsion angle β6 of the tooth tip 45bt, respectively.

  Here, the standard of the twist angle is the direction ηr, which is indicated by a two-dot chain line. The direction ηr is orthogonal to both the directions ξr and ζr. The direction in which the tooth tips 45at and 45bt extend is indicated by a one-dot chain line.

  Similar to the first embodiment, the twist angle is grasped along the direction ζr of a certain tooth.

  Here, the twist angle β5 of the tooth surface 45a is counterclockwise, and the twist angle β6 of the tooth surface 45b is clockwise.

  FIG. 7 is a plan view of a portion of the configuration of the toothed belt 4B, which can be grasped as a rack, as viewed along the direction ζr. FIG. 8 is a plan view of a portion of the configuration of the toothed belt 4B that can be grasped as a rack along a direction opposite to the direction ηr.

  In FIG. 7, the tooth surfaces 45a and 45b illustrate the case where both are planes. Accordingly, the torsion angles β5 and β6 are all based on the direction ξr (the reference is indicated by a two-dot chain line), and the directions of the components orthogonal to the direction ζr among the normal lines of the tooth surfaces 45a and 45b (both are one-dot chain lines). It is expressed as an angle formed by This is because the directions ξr and ηr are orthogonal to each other.

  In plan view along the direction ζr, the tooth 43 has a tooth thickness at a position in contact with the tooth bottom 40 extending from the width 43e to the width 43d along the direction opposite to the direction ηr. Similarly, the tooth thickness of the tooth 44 at the position in contact with the root 40 increases from the width 44d to the width 44e along the direction ηr. For example, the widths 43e and 44d are equal, and the widths 43d and 44e are equal.

  From the above, it can be understood that the toothed belt 4B includes the following [Feature 5] and [Feature 6] similar to the [Feature 3] and [Feature 4] described above.

[Feature 5]
(5a) The toothed belt 4B has tooth surfaces 45a and 45b;
(5b) The tooth surfaces 45a and 45b are both driven in the same direction ξr when viewed along the direction ζr from the end of the tooth 43 (or the tooth 44) toward the root.
(5c) When viewed along the direction ζr from the end of the tooth 43 (or the tooth 44) toward the root, the tooth surfaces 45a and 45b have twist angles β5 and β6 opposite to each other;
(5d) The tooth surfaces 45a and 45b are adjacent in the direction ξr.

  [Characteristic 6] The tooth surfaces 45a and 45b satisfying the above [Characteristic 5] are alternately arranged in the root 40.

  Here, since the toothed belt 4B has, for example, a ring shape, the tooth bottom 40 can be grasped only as the inner side, not the same side, that is, both the outer side and the inner side.

  The teeth 43 and 44 have different tooth thicknesses depending on the direction ηr. With reference to FIG. 7, the tooth thickness of the teeth 43 becomes thinner and the tooth thickness of the teeth 44 becomes thicker in the direction ηr.

  Therefore, the teeth 43 and 44 can be grasped as being alternately arranged along the direction ξr so that the tooth shape itself is the same and the direction in which the tooth thickness increases is different.

  However, like [Feature 4], the tooth thickness itself is not necessarily the premise for obtaining the operation of this embodiment.

  Further, in the feature (5b), attention should be paid to a certain tooth, and the driving direction of the tooth surfaces 45a and 45b is determined by looking along the direction ζr from the tooth end to the tooth base. That is. This is the same as pointed out in feature (1b).

  It can be said that the teeth 43 and 44 of the toothed belt 4B have tooth surfaces 45a and 45b.

  FIG. 9 is a perspective view partially showing a toothed pulley 5B that meshes with the toothed belt 4B and drives the toothed belt 4B. The toothed pulley 5B includes teeth 56 and 57 and can be grasped as an external gear. The direction connecting the toothed belt 4B and the toothed pulley 5B is substantially parallel to the direction ζr.

  The teeth 56 and 57 protrude with respect to the root 50, and the direction ζp when the tooth root is viewed from the end of each tooth is not parallel to the direction ξp in which the toothed pulley 5B rotates. In the illustration of FIG. 9, the directions ξp and ζp are orthogonal to each other.

  The tooth 56 has a tooth crest 56c and a pair of tooth surfaces 56a. The tooth 57 has a tooth crest 57c and a pair of tooth surfaces 57a. Also in FIG. 9, the tooth tip 56t of the tooth 56 is shown as the boundary between the tooth crest 56c and the tooth surface 56a. However, as described in the first embodiment, this is a convenient illustration, and does not necessarily mean that the tooth tip 56t coincides with the boundary between the tooth top 56c and the tooth surface 56a.

  Similarly to the tooth 56, the tooth 57 has a tooth crest 57c and a pair of tooth surfaces 57a, and a tooth tip 55t appears.

  In FIG. 9, as in FIG. 4, the torsion angles of the tooth surfaces 56a and 57a are represented as the torsion angle β7 of the tooth tip 56t and the torsion angle β8 of the tooth tip 57t, respectively.

  Here, the standard of the twist angle is the direction ηp, which is indicated by a two-dot chain line. The direction ηp is orthogonal to both the directions ξp and ζp. The direction in which the tooth tips 56t and 57t extend is indicated by a one-dot chain line.

  As in the first embodiment, the twist angle is grasped along the direction ζp for a certain tooth. Here, the twist angle β7 of the tooth surface 56a is counterclockwise, and the twist angle β8 of the tooth surface 57a is clockwise.

  From the above, it can be understood that the toothed pulley 5B includes the following [Feature 7] and [Feature 8] similar to the above [Feature 1] and [Feature 2].

[Feature 7]
(7a) The toothed pulley 5B has tooth surfaces 56a and 57a;
(7b) The tooth surfaces 56a and 57a are both driven in the same direction ξp when viewed along the direction ζp from the end of the tooth 56 (or the tooth 57) toward the tooth root;
(7c) When viewed along the direction ζp from the end of the tooth 56 (or the tooth 57) toward the tooth root, the tooth surfaces 56a and 57a exhibit twist angles β7 and β8 opposite to each other;
(7d) The tooth surfaces 56a and 57a are adjacent in the direction ξp.

  [Characteristic 8] The teeth of the toothed pulley 5B are divided into teeth 56 having a tooth surface 56a whose twist direction is counterclockwise and teeth 57 having a tooth surface 57a whose twist direction is clockwise. The

  Furthermore, it can be understood as a feature that the teeth 56 and 57 are alternately arranged along the direction ξp.

  It should be noted in the feature (7b) that the driving direction of the tooth surfaces 56a and 57a is determined by paying attention to one tooth and looking along the direction ζp from the end of the tooth toward the root. It is. This is similar to the pointed out in feature (3b).

  Therefore, in the same manner as in the first embodiment, the torsion angle β6 and the torsion angle β7 are set to the same degree, and the torsion angle β5 and the torsion angle β8 are set to the same degree, so that the toothed pulley 5B and the toothed pulley 5B are provided. The belt 4B meshes. More specifically, the toothed belt 4B and the toothed pulley 5B can be meshed so that the tooth surface 57a contacts the tooth surface 45a and the tooth surface 56a contacts the tooth surface 45b. Needless to say, the pitches are aligned between the toothed pulley 5B and the toothed belt 4B.

  FIG. 10 is a plan view showing a state in which the toothed belt 4B and the toothed pulley 5B are engaged with each other. The plane is a plane viewed along the direction ηr when viewed from the toothed belt 4B, and is a plane viewed along the direction opposite to the direction ηp when viewed from the toothed pulley 5B.

  In FIG. 10, the directions ξr and ζr are different between the left side and the right side in FIG. 5 because the directions ξr and ζr are different between the left side and the right side in FIG.

  As described above, the thrust force is reduced or offset, and the toothed belt 4B is unlikely to be detached from the toothed pulley 5B.

Example (based on Embodiment 1 and Embodiment 2).
The first embodiment and the second embodiment are in a relationship in which the tooth shape is exchanged between the toothed belt and the toothed pulley. Therefore, both have the same effect of reducing or canceling the thrust force described above, and the action when this effect is obtained.

  Therefore, examples of these two embodiments will be described including the effects compared with the prior art.

  11 and 12 are perspective views showing a combination of the toothed belt 4Q, the driving-side toothed pulley 5 and the driven-side toothed pulley 6 in the prior art.

  The toothed pulley 5 is connected to the drive device 1 and is driven by the drive device 1. For example, a motor is employed as the driving device 1. The toothed belt 4Q is hung on both the toothed pulleys 5 and 6. The teeth (not shown) of the toothed belt 4Q mesh with both the teeth of the toothed pulley 5 (abbreviated by line segment) and the teeth of the toothed pulley 6 (abbreviated by line segment). The teeth of the toothed belt 4Q are, for example, left-handed oblique teeth, and the teeth of the toothed pulleys 5 and 6 are right-handed oblique teeth.

  The power for the drive device 1 to rotate the toothed pulley 5 is transmitted from the toothed pulley 5 to the toothed pulley 6 via the toothed belt 4Q. In FIG. 11, the direction in which the toothed pulleys 5 and 6 rotate is indicated by arc-shaped arrows, and the direction in which the toothed belt 4Q is driven is indicated by upward and downward arrows in the drawing. The combination of the toothed belt 4Q and the toothed pulleys 5 and 6 can be grasped as a drive transmission device.

  FIG. 12 schematically shows such problems of the conventional technique. Each of the toothed pulleys 5 and 6 rotates in the Θ direction with the Z direction as a rotation axis. The Θ direction has a relationship between the so-called spiral direction of the right screw and the direction in which the right screw travels with respect to the Z direction.

  Since the toothed belt 4Q moves back and forth between the toothed pulleys 5 and 6, the tooth twist angle of the toothed pulleys 5 and 6 and the tooth twist angle of the toothed belt 4Q are all aligned with the twist angle α. . Assuming that the tooth trace is along the T direction, the twist angle α can be grasped as an angle formed by the Z direction and the T direction.

  If the angle between the Θ direction and the T direction is less than 90 degrees at the position where the toothed pulley 5 (or the toothed pulley 6) and the toothed belt 4Q are engaged with each other, the drive device 1 causes the toothed pulley 5 to move. The power to be rotated has a component force directed in the T direction. Conversely, if the angle is greater than 90 degrees, the power has a component force directed in the direction opposite to the T direction.

  That is, if the teeth of the toothed pulleys 5 and 6 are right-twisted oblique teeth, the toothed belt 4Q along the direction in which the rotation can be seen in the clockwise direction along the rotation axis of the rotation. Receives thrust. If the teeth of the toothed pulleys 5 and 6 are counterclockwise inclined teeth, the direction in which the toothed belt 4Q receives the thrust force is reversed.

  FIG. 12 illustrates a case where both the toothed pulleys 5 and 6 are grasped as right pinions. Therefore, the case where the toothed belt 4Q receives the thrust force in the Z direction and moves in the Z direction is illustrated.

  However, by adopting the toothed belts 4A and 4B and the toothed pulleys 5A and 5B according to the first and second embodiments, the toothed belts 4A and 4B are provided in the direction of the rotation axis of the toothed pulleys 5A and 5B. The thrust force along is reduced or offset. As mentioned above, these have teeth whose tooth surfaces are twisted in opposite directions, so that such thrust forces are reduced with each other.

  13 and 14, any of the toothed belts 4A and 4B is adopted as the component 4A / 4B, and any of the toothed pulleys 5A and 5B is adopted as the component 5A / 5B. . However, when the toothed belt 4A is employed as the component 4A / 4B, the toothed pulley 5A is employed as the component 5A / 5B, and when the toothed belt 4B is employed as the component 4A / 4B, the component 5A / A toothed pulley 5B is adopted as 5B.

  In both FIG. 13 and FIG. 14, the teeth of the component 4A / 4B are omitted, and the teeth of the component 5A / 5B are abbreviated as line segments without considering the twist angle.

  The component 4A / 4B is hung on both of the pair of components 5A / 5B. The components 5A / 5B connected to the driving device 1 function as a driving-side toothed pulley and are driven by the driving device 1. Thereby, the component 4A / 4B circulates between the pair of components 5A / 5B. The combination of the component 4A / 4B and the component 5A / 5B can be grasped as a drive transmission device.

  In both FIG. 13 and FIG. 14, the component 4A / 4B is unlikely to be detached from the component 5A / 5B.

  In the illustration of FIG. 13, the moving body 10 is provided with respect to the component 4A / 4B. As a result, the movement of the constituent elements 4A / 4B is converted into the movement of the moving body 10 moving linearly.

  In the illustration of FIG. 14, the rotating body 11 is provided with respect to the component 5A / 5B which functions as a driven-side toothed pulley. As a result, the movement of the component 4A / 4B is converted into the movement of the rotating body 11 rotating.

  For example, a rod-like component can be connected to the rotating body 11. In this case, the component can be used as a crossing bar.

  For example, the rotary body 11 can be used as a rotary table. From the viewpoint of keeping the rotary table horizontal, it is desirable that the rotation axes of the constituent elements 5A / 5B be arranged vertically.

Embodiment 3 FIG.
In the technology described in the first and second embodiments, it is easy to adopt a simple left pinion or right pinion as a toothed pulley used in combination with any of the toothed belts 4A and 4B. is not.

  However, a simple left pinion or right pinion can be used as a toothed pulley by using a toothed belt having inclined teeth that twist in an appropriate direction on both sides. Moreover, power can be transmitted while reducing or canceling the thrust force.

  FIG. 15 is a perspective view partially showing the configuration of the toothed belt 4C described in the third embodiment. The toothed belt 4C is formed in, for example, a ring shape, but the perspective view shows a flat portion of the toothed belt 4C.

  In this portion, similarly to the toothed belts 4A and 4B, the toothed belt 4C can be grasped as a rack. Similarly to the toothed belts 4A and 4B, the toothed belt 4C can also be understood as having a configuration in which the rack and a part of the internal gear are connected in the driving direction. Furthermore, it can be grasped that the rack and a part of the external gear have a configuration connected in the driving direction.

  The toothed belt 4C is driven in the direction ξr. In FIG. 15, since the portion where the toothed belt 4C is flat is shown, the direction ξr is also shown as a linear direction.

  The toothed belt 4 </ b> C has a tooth bottom 40 </ b> A on one surface facing in the thickness direction and a tooth bottom 40 </ b> B on the other surface. The toothed belt 4 </ b> C has teeth 46 and 47. The teeth 46 and 47 protrude with respect to the roots 40A and 40B, respectively. The directions in which the teeth 46 and 47 protrude from the roots 40A and 40B are almost opposite to each other. The direction ζr of the tooth 46 viewed from the end of the tooth 46 is not parallel to the direction ξr. In the illustration of FIG. 15, the directions ξr and ζr are orthogonal to each other. The direction connecting the toothed belt 4C and the toothed pulley meshing with the toothed belt 4C is substantially parallel to the direction ζr.

  The tooth 46 has a tooth crest 46c and a pair of tooth surfaces 46a. In FIG. 15, the tooth tip 46t of the tooth 46 is shown as a boundary between the tooth crest 46c and the tooth surface 46a. However, this does not necessarily mean that the tooth tip 46t coincides with the boundary between the tooth crest 46c and the tooth surface 46a, as in the drawings employed in the first and second embodiments.

  Similarly to the tooth 46, the tooth 47 has a tooth crest 47c and a pair of tooth surfaces 47a, and a tooth tip 47t appears.

  In FIG. 15, the torsion angles of the tooth surfaces 46a and 47a are represented as the torsion angle β9 of the tooth tip 46t and the torsion angle β10 of the tooth tip 47t, respectively.

  Here, the standard of the twist angle is the direction ηr, which is indicated by a two-dot chain line. The direction ηr is orthogonal to both the directions ξr and ζr. The direction in which the tooth tips 46t and 47t extend is indicated by a one-dot chain line.

  However, the twist angle is grasped along the direction ζr for a certain tooth 46. Here, the twist angle β9 of the tooth surface 46a is clockwise, and the twist angle β10 of the tooth surface 47a is counterclockwise.

  16, FIG. 17, and FIG. 18 are plan views showing a portion that can be grasped as a rack in the configuration of the toothed belt 4C. FIG. 16 is a plan view of the portion viewed along the direction ζr. FIG. 17 is a plan view of the portion as viewed along the direction opposite to the direction ζr. FIG. 18 is a plan view of the portion as seen along the direction opposite to the direction ηr.

  In FIG. 16 and FIG. 17, the tooth surfaces 46a and 47a exemplify a case where both are flat surfaces. Accordingly, the torsion angles β9 and β10 are each based on the direction ξr (the reference is indicated by a two-dot chain line), and the directions of the components orthogonal to the direction ζr among the normal lines of the tooth surfaces 46a and 47a (both are one-dot chain lines) It is expressed as an angle formed by This is because the directions ξr and ηr are orthogonal to each other.

  From the above, it can be understood that the toothed belt 4C has the following [Feature 9] similar to [Feature 1], [Feature 3], [Feature 5], and [Feature 7] described above.

[Feature 9]
(9a) The toothed belt 4C has tooth surfaces 46a and 47a;
(9b) The tooth surfaces 46a and 47a are both driven in the same direction ξr as viewed along the direction ζr from the end of the tooth 46 toward the tooth root;
(9c) The tooth surfaces 46a and 47a have twist angles β9 and β10 that are opposite to each other when viewed along the direction ζr from the end of the tooth 46 toward the tooth root;
(9d) The tooth surfaces 46a and 47a are adjacent in the direction ζr.

  It should be noted in the feature (9b) that the driving direction of the tooth surfaces 46a and 47a is determined by paying attention to a certain tooth 46 and looking along the direction ζr from the end of the tooth toward the tooth base. is there.

  In addition, the characteristics (1d), (3d), (5d), (7d), and (9d) indicate that in the direction orthogonal to both the direction from the end of the target tooth toward the root and the direction in which the tooth surface is driven This is common in that the two tooth surfaces are not adjacent.

  Further, the toothed belt 4C can be grasped as having the following [Feature 10].

[Feature 10]
A surface in which the teeth 46 are arranged in the direction ξr (which includes the root 40A) and a surface in which the teeth 47 are arranged in the direction ξr (which includes the bottom 40B) face each other in the direction ζr.

  The toothed belt 4C illustrated in FIGS. 15 to 18 can be grasped as a toothed belt having inclined teeth on both surfaces and the inclined teeth on either surface being right-handed. Of course, the toothed belt in which the inclined teeth are provided on both surfaces and the inclined teeth on either surface are left-hand-twisted has the same effect as the toothed belt 4C.

  Thus, the features (7b) and (7c) can be realized by aligning the twist directions of the inclined teeth provided on both surfaces. This is because when viewed along the direction ζr, the twisting direction of the teeth provided on either one of the two surfaces is opposite to the twisting direction in the normal sense.

  The toothed belt 4C includes a toothed pulley that functions as a right pinion both from the inner peripheral side (for example, the side where the teeth 46 are provided) and from the outer peripheral side (for example, the side where the teeth 47 are provided). Engage.

  The rotation direction of the toothed pulley that meshes from the inner peripheral side of the toothed belt 4C and the toothed pulley that meshes from the outer peripheral side are opposite. Each of these toothed pulleys functions as a right pinion. Therefore, as described with reference to FIG. 12, the force acting on the toothed belt 4C by meshing with the toothed pulley meshing from the inner peripheral side is the force acting on the toothed belt 4C by meshing with the toothed pulley meshing from the outer peripheral side. And vice versa.

  Accordingly, the thrust force is reduced or offset, and the toothed belt 4C is less likely to be detached from the toothed pulley.

Example (based on Embodiment 3).
19 to 22 are perspective views showing a combination of a toothed belt and a toothed pulley to which the third embodiment can be applied. These combinations can also be grasped as a drive transmission device.

  In any of FIGS. 19 to 21, the teeth of the toothed belt 4C are omitted, and the teeth of the toothed pulleys 5C, 5D, and 5E are abbreviated as line segments without considering the twist angle. In FIG. 22, the shape of the tooth is shown in part, and the tooth is abbreviated in the other part.

  In FIG. 19, the toothed belt 4 </ b> C is held by the toothed pulley 5 </ b> C from the inner peripheral side and is engaged by the toothed pulley 5 </ b> D from the outer peripheral side.

  The driving device 1 drives the driving-side toothed pulley 5C. The toothed belt 4C meshing with the toothed pulley 5C not only rotates the driven toothed pulley 5C but also drives the toothed pulley 5D. The toothed pulley 5D functions as an auxiliary pulley that sandwiches the toothed belt 4C together with the toothed pulley 5C.

  The thrust force acting between the toothed pulley 5C and the toothed belt 4C is opposite to the thrust force acting between the toothed pulley 5D and the toothed belt 4C. Therefore, the toothed belt 4C is difficult to come off from the toothed pulley 5C.

  The toothed pulley 5D may be provided corresponding to only one of the driving-side toothed pulley 5C and the driven-side toothed pulley 5C. However, from the viewpoint of reducing the thrust force, it is desirable to provide a toothed pulley 5D corresponding to each of the toothed pulleys 5C as illustrated in FIG.

  In FIG. 20, the toothed belt 4C is held by the toothed pulley 5C from the inner periphery side and is engaged by the toothed pulley 5E from the outer periphery side.

  The toothed pulley 5E functions as a tensioner rather than sandwiching the toothed belt 4C together with the toothed pulley 5C like the toothed pulley 5D. Specifically, the toothed pulley 5E is movable in a direction 7 in which the toothed belt 4 is pressed from the outer peripheral side toward a line connecting the pair of toothed pulleys 5C (indicated by a one-dot chain line in the figure). Based on this pressing force, the tension of the toothed belt 4C that circulates between the toothed pulleys 5C is adjusted.

  Similarly to the toothed pulley 5D, the toothed pulley 5E applies a thrust force to the toothed belt 4C in a direction opposite to the toothed pulley 5C. Therefore, the toothed belt 4C is difficult to come off from the toothed pulley 5C.

  In FIG. 21, the toothed belt 4C is held by and meshed with the four toothed pulleys 5C from the inner peripheral side and the toothed pulley 5E from the outer peripheral side.

  When the toothed belt 4C is held by three or more toothed pulleys 5C from the inner peripheral side in this way, it is possible to provide the toothed pulley 5D sandwiching the toothed belt 4C together with the toothed pulley 5C with two teeth. It becomes more difficult than when it is held by the attached pulley 5C (see FIG. 19).

  In such a case, it is desirable to hold by the toothed pulley 5E from the outer peripheral side of the toothed belt 4C. The toothed pulley 5 </ b> E is movable in the direction 7 and presses the toothed belt 4 from the outer peripheral side along the direction 7. The direction 7 goes from a position where the toothed pulley 5E contacts the toothed belt 4C to a line (indicated by a one-dot chain line in the figure) connecting the pair of toothed pulleys 5C on which the toothed belt 4C is engaged.

  FIG. 22 illustrates a case where the toothed belt 4C is formed in a linear shape instead of a ring shape. The toothed belt 4C is fixed by providing belt clamps 15 at both ends.

  The driving device 1 and the toothed pulleys 5C and 5F are placed on the moving body 10, and the moving body 10 is movable between both ends of the toothed belt 4C. The toothed pulleys 5C and 5F mesh with a fixed toothed belt 4C. When the toothed pulley 5C driven by the driving device 1 rotates, the driving device 1 and the toothed pulleys 5C and 5F move between both ends of the toothed belt 4C together with the moving body 10.

  The toothed pulley 5F contributes to increasing the length of the toothed belt 4C wound around the toothed pulley 5C. Further, similarly to the toothed pulley 5D, the toothed pulley 5F applies a thrust force to the toothed belt 4C in the direction opposite to the toothed pulley 5C. Therefore, the toothed belt 4C is difficult to come off from the toothed pulley 5C.

  In the configuration shown in FIG. 22, a toothed belt 4A or a toothed belt 4B may be used instead of the toothed belt 4C. In this case, the toothed pulley 5C is not a simple bevel gear, and is replaced with a toothed pulley 5A or a toothed pulley 5B.

  In this case, the thrust force is reduced or offset by the toothed belt 4A or the toothed belt 4B and the toothed pulley 5A or the toothed pulley 5B. Therefore, the toothed belts 4A and 4B need only have teeth on one side. Therefore, the toothed pulley 5F is replaced with a simple cylindrical pulley.

  In any of the above-described embodiments and examples, the side surface shape of the tooth may be a trapezoidal shape or a semicircular shape, as long as it has a shape that can function as a gear tooth.

  In addition to the toothed belt and the toothed pulley, each embodiment can also be adopted in a power transmission mechanism using a normal gear.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

  4A-4C toothed belt, 5A-5F toothed pulley, 41-44, 46, 47, 53, 54, 56, 57 teeth, 41a, 42a, 45a, 45b, 46a, 47a, 55a, 55b, 56a, 57a Tooth surface, β1 to β10 twist angle, ξr, ηr, ζr, ξp, ηp, ζp directions.

Claims (12)

A gear comprising a plurality of teeth,
A first tooth surface and a second tooth surface that are driven in the same second direction and have twist angles opposite to each other when viewed along a first direction from the end of the tooth toward the root of the tooth. Tooth surface,
The first tooth surface and the second tooth surface are:
Adjacent in the first direction or the second direction;
A gear that is not adjacent to a third direction orthogonal to either the first direction or the second direction.   The gear according to claim 1, wherein the first tooth surface and the second tooth surface are alternately arranged on the same side surface. The gear according to claim 2, wherein the teeth include teeth that exhibit both the first tooth surface and the second tooth surface.   The gear according to claim 1, wherein the teeth are divided into a first tooth that exhibits the first tooth surface and a second tooth that exhibits the second tooth surface.   The gear according to claim 4, wherein the first teeth and the second teeth are alternately arranged on the same side surface. A first surface on which the first teeth are arranged in the second direction;
5. The gear according to claim 4, further comprising: a second surface arranged in the second direction, the second surface facing the first surface in the first direction.   A drive transmission device comprising a toothed belt as a gear according to claim 3 and a toothed pulley as a gear according to claim 4, wherein the toothed belt and the toothed pulley mesh with each other.   A drive transmission device comprising a toothed belt that is a gear according to claim 4 and a toothed pulley that is a gear according to claim 3, wherein the toothed belt and the toothed pulley mesh with each other.   A drive transmission device comprising: a toothed belt that is a gear according to claim 6; a toothed pulley that meshes from an inner peripheral side of the toothed belt; and a toothed pulley that meshes from an outer peripheral side of the toothed belt.   The drive transmission device according to claim 9, wherein a pair of the toothed pulleys sandwich the toothed belt.   The drive transmission device according to claim 9, wherein two or more toothed pulleys that mesh with the toothed belt from the inner peripheral side are provided, and the toothed pulley that meshes with the toothed belt from the outer peripheral side functions as a tensioner. .   The drive transmission device according to any one of claims 7 to 11, wherein the toothed belt is linear, both ends thereof are fixed, and the toothed pulley is movable between both ends of the toothed belt.

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