JP2020041568A - Scissors gear - Google Patents

Abstract

To inhibit inclination of a sub gear.SOLUTION: A scissors gear G includes: a main gear 1 having a cylindrical boss 10 at an inner periphery part; a sub gear 2 which fits in the boss so as to enable relative rotation; a spring 8 which biases the sub gear to the main gear in a circumferential direction; and a positioning member which positions the sub gear in an axial direction. The positioning member is formed by a ring plate 6 fixed to the boss.SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to scissor gears.

  Among the gears, there is a scissors gear that removes backlash with a mating gear in order to reduce rattle noise due to rattling vibration. The scissors gear includes a main gear having a cylindrical boss on an inner peripheral portion, a sub gear fitted to the boss so as to be relatively rotatable, and a spring for urging the sub gear in a circumferential direction with respect to the main gear. The backlash is removed by sandwiching the teeth of the mating gear with the teeth of the sub gear.

JP-A-62-34258

  In this scissors gear, the sub gear fitted to the boss is positioned in the axial direction. Generally, the positioning in the axial direction is performed by a snap ring detachably attached to a ring groove of the boss.

  However, the width of the ring groove is made slightly larger than the thickness of the snap ring because it is necessary to securely fit the snap ring into the ring groove. Then, a gap is formed between the snap ring and the sub gear due to the dimensional difference, and the sub gear may fall down or tilt. Such tilting or tilting of the sub-gear may prevent proper torque transmission, meshing with a mating gear, or increase noise, and should be avoided as much as possible.

  Accordingly, the present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide a scissor gear that can suppress the inclination of the sub gear.

According to one aspect of the present disclosure,
A main gear having a cylindrical boss on the inner periphery;
A sub-gear fitted to the boss so as to be relatively rotatable,
A spring that urges the sub-gear in the circumferential direction with respect to the main gear;
A positioning member for positioning the sub-gear in the axial direction;
With
The scissors gear is provided, wherein the positioning member is formed by a ring plate fixed to the boss.

Preferably, the boss has a gear fitting surface for fitting the sub-gear, and a ring fitting surface axially adjacent to the gear fitting surface,
The ring plate is fitted and fixed to the ring fitting surface.

  Preferably, the ring fitting surface has a smaller diameter than the gear fitting surface, and a step surface extending in the radial direction is provided between the gear fitting surface and the ring fitting surface. The ring plate is disposed flush with an end surface of the sub-gear fitted to the fitting surface, and the ring plate is slidably contacted with the sub-gear and fitted to the ring fitting surface in a state of contacting the step surface. Fixed together.

  Preferably, the ring plate is shrink-fit to the ring fitting surface.

  According to the present disclosure, the inclination of the sub gear can be suppressed.

1 is a front view of a scissors gear according to an embodiment of the present disclosure. It is a longitudinal section side view of a scissors gear concerning an embodiment of the present disclosure. It is a vertical side view of the scissors gear of a comparative example.

  Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that the present disclosure is not limited to the following embodiments.

  FIG. 1 is a front view of a scissors gear according to the embodiment of the present disclosure. FIG. 2 is a vertical sectional side view of the scissor gear. The scissor gear G includes a main gear 1 and a sub gear 2, and a combination of these two gears 1 and 2 constitutes one scissor gear G, that is, a gear assembly. C indicates a central axis (referred to as a gear axis) of the scissors gear G. Hereinafter, unless otherwise specified, the axial direction, the radial direction, and the circumferential direction refer to the axial direction, the radial direction, and the circumferential direction based on the gear axis C. For convenience, the right side of FIG. 2 is referred to as an axial front, and the left side of FIG. 2 is referred to as an axial rear. FIG. 1 is a front view when viewed from the front in the axial direction.

  The scissors gear G is configured as a helical gear having outer peripheral teeth, and is applied so as to mesh with a mating gear (not shown). The scissor gear G may be configured as another type of gear, for example, a spur gear.

  The main gear 1 and the sub gear 2 are arranged adjacent to each other in the axial direction, and the sub gear 2 is arranged adjacent to the front of the main gear 1 in the axial direction.

  The main gear 1 and the sub gear 2 each have a main tooth portion 11 and a sub tooth portion 12 on the outer peripheral portion. The main tooth portion 11 and the sub tooth portion 12 have the same module, number of teeth, and tooth shape. The main teeth 11 and the sub teeth 12 are formed as if the teeth of one gear were divided in the thickness direction. Both the main teeth 11 and the sub teeth 12 are meshed with the mating gear. The sub gear 2 is mainly used for removing backlash, and is not actively used for transmitting driving force. Therefore, the tooth width of the sub-tooth portion 12 is made smaller than the tooth width of the main gear 1.

  The main gear 1 integrally has a cylindrical boss 10 on an inner peripheral portion thereof. On the other hand, the sub-gear 2 is integrally formed generally in a ring plate shape, and has a fitting hole 5 on an inner peripheral portion thereof. By fitting the fitting hole 5 to the gear fitting surface 4 formed on the outer peripheral portion of the boss 10, the sub gear 2 is fitted to the boss 10 so as to be relatively rotatable and coaxial.

  A positioning member for positioning the sub gear 2 in the axial direction is fixed to the boss 10. In the present embodiment, the positioning member is formed by the ring plate 6. This positioning member will be described later in detail.

  A shaft hole 11A is provided in the inner peripheral portion of the boss 10, and a shaft (not shown) is inserted into the shaft hole 11A. In the present embodiment, the cylindrical sliding bearing 3 is fixed to the shaft hole 11A by press-fitting, and the sliding bearing 3 is fitted to the shaft. The scissors gear G rotates around this shaft.

  However, the scissors gear G may be directly fitted to the shaft, or may be fixed to the shaft.

  A spring chamber 7 is formed in the scissors gear G, and a spring 8 that urges the sub gear 2 in the circumferential direction with respect to the main gear 1 is housed in the spring chamber 7. The spring chamber 7 is formed by an axial gap between a ring-shaped groove 9 provided on the front surface of the main gear 1 and a rear surface of the sub gear 2.

  The spring 8 is a C-shaped torsion spring in the present embodiment, but the type thereof can be changed. A main pin 13 for locking one end of the spring 8 is fixed at a predetermined phase position on the bottom surface of the groove 9 in the main gear 1 by press fitting or the like. Also, a sub-pin 14 for locking the other end of the spring 8 is fixed at a predetermined phase position on the rear surface of the sub gear 2 facing the bottom surface of the groove 9 by press fitting or the like. The main pin 13 and the sub-pin 14 are sandwiched by the spring 8, and the concave seats 15, 16 formed at one end and the other end of the spring 8 are seated on the main pin 13 and the sub-pin 14, respectively, so that one end and the other end of the spring 8 are The main pin 13 and the sub-pin 14 are locked.

  In a state where the sub gear 2 is merely assembled to the main gear 1, the phases of the main gear 1 (main tooth portion 11) and the sub gear 2 (sub tooth portion 12) are out of phase, and cannot be meshed with the mating gear. In order to mesh with the mating gear, the main gear 1 and the sub gear 2 must be twisted against each other against the urging force of the spring 8, push the spring 8 open, and make them have the same phase.

  In order to keep the main gear 1 and the sub gear 2 in the same phase, the scissors gear G is provided with a fixing bolt 17. The fixing bolt 17 is inserted from the front into an insertion hole 18 provided in the sub gear 2 and screwed into a screw hole 19 provided in the main gear 1 to be tightened. Of course, the insertion hole 18 and the screw hole 19 are coaxial when the main gear 1 and the sub gear 2 have the same phase. By maintaining the main gear 1 and the sub gear 2 in the same phase in this manner, the scissors gear G can be easily meshed with the mating gear. After the engagement, the fixing bolt 17 is removed.

  Next, the axial positioning of the sub gear 2 will be described.

  First, the base portion 22 of the sub-tooth portion 12 located on the outer peripheral portion of the sub-gear 2 is slidably in surface contact with the base portion 21 of the main tooth portion 11 located on the outer peripheral portion of the main gear 1. Thus, the sub gear 2 is positioned with respect to the axial rearward direction so as not to move further axially rearward.

  Next, the inner peripheral end 23 of the sub gear 2 is slidably brought into surface contact with the ring plate 6 as a positioning member. As a result, the sub gear 2 is positioned axially forward so as not to move further forward in the axial direction.

  The boss 10 has a ring fitting surface 24 adjacent to the gear fitting surface 4 axially forward. The ring fitting surface 24 has a smaller diameter than the gear fitting surface 4 and extends in the axial direction to the front end of the boss 10. Between the gear fitting surface 4 and the ring fitting surface 24, a step surface 25 extending in the radial direction and connecting them is provided. The step surface 25 is perpendicular to the axial direction. The step surface 25 is arranged flush with the front end surface of the sub gear 2 fitted to the gear fitting surface 4.

  On the other hand, the positioning member of the present embodiment is formed by a ring-shaped ring plate 6 extending all around, and is fitted and fixed to the ring fitting surface 24. In the case of the present embodiment, the ring plate 6 is fixed to the ring fitting surface 24 by shrink fitting. The cross-sectional shape of the ring plate 6 is rectangular as shown in FIG.

  The ring plate 6 is shrink-fitted to the ring fitting surface 24 in a state of contacting the step surface 25. Thus, the ring plate 6 can be easily positioned rearward in the axial direction during shrink fitting, and the ring plate 6 can be fixed at an accurate axial position.

  When the ring plate 6 is fixed in this way, the ring plate 6 naturally comes into slidable surface contact with the sub gear 2.

  The ring plate 6 has a predetermined outer diameter D, and the outer diameter D is set relatively large. Accordingly, the ring plate 6 can be supported in the axial direction up to a relatively outer peripheral portion of the sub gear 2.

  Next, the operation and effect of the present embodiment will be described.

  The scissors gear G is meshed with the mating gear while the main gear 1 and the sub gear 2 are held in the same phase by the fixing bolt 17. Thereafter, when the fixing bolt 17 is removed, the spring 8 contracts, and the phases of the main gear 1 and the sub gear 2 are shifted. As a result, the teeth of the main gear 1 and the teeth of the sub gear 2 sandwich the teeth of the mating gear, and backlash is eliminated. Further, rattle noise due to rattling vibration can be reduced.

  By the way, in a comparative example different from the present embodiment, as shown in FIG. 3, the positioning of the sub gear 2 in the axial direction is performed by a snap ring 32 which is detachably attached to the ring groove 31 of the boss 10. As is well known, the snap ring 32 is a C-shaped metal ring which can be expanded and contracted, and is mainly attached and detached manually by using a tool such as a snap ring plier.

  Since it is necessary to securely fit the snap ring 32 into the ring groove 31, the width Wx of the ring groove 31 is made slightly larger than the thickness tx of the snap ring 32. Then, a gap is formed between the snap ring 32 and the sub-gear 2 due to the dimensional difference, and the sub-gear 2 may fall or tilt as shown by the imaginary line a. Such a fall or inclination of the sub-gear 2 prevents proper torque transmission, meshing with a mating gear or increases noise, and therefore should be avoided as much as possible.

  Therefore, in the present embodiment, the sub gear 2 is positioned by the ring plate 6 instead of the snap ring 32. This eliminates the need for providing a gap between the ring groove 31 and the snap ring 32 as described above, and can suppress the inclination of the sub gear 2. That is, by fixing the ring plate 6 at a position where the ring plate 6 slidably contacts the sub-gear 2, the gap between the ring plate 6 and the sub-gear 2 can be substantially eliminated, and the inclination of the sub-gear 2 can be suppressed. . Therefore, various problems caused by the inclination of the sub gear 2 can be solved.

  In addition, since the step surface 25 is arranged flush with the front end surface of the sub gear 2, the ring plate 6 is brought into contact with the sub gear 2 slidably at the same time that the ring plate 6 is abutted against the step surface 25, The work of assembling the ring plate 6 can be facilitated.

  Further, since a standard product is usually used for the snap ring 32 in the comparative example, if the inner diameter is determined, the outer diameter is naturally determined. Therefore, the outer diameter cannot be made too large, and only the vicinity of the inner peripheral end of the sub gear 2 can be supported, which is disadvantageous for suppressing the inclination of the sub gear 2.

  However, the outer diameter D of the ring plate 6 of the present embodiment can be set relatively freely. Therefore, the outer diameter D is made larger than the outer diameter of the snap ring 32, and the sub gear 2 can be supported at a position further outward in the radial direction. Therefore, this is also advantageous for suppressing the inclination of the sub gear 2.

  Although the embodiments of the present disclosure have been described above in detail, various other embodiments of the present disclosure are also conceivable.

  (1) For example, the cross-sectional shape of the ring plate 6 may be a shape other than a square.

  (2) The ring plate 6 may be fixed by a method other than shrink fitting. For example, it may be fixed by a method such as bolting or directly screwing into a male screw formed on the boss 10.

  The embodiments of the present disclosure are not limited to the above-described embodiments, but include all modifications, applications, and equivalents included in the spirit of the present disclosure defined by the claims. Therefore, the present disclosure should not be construed as limiting, but can be applied to any other technology belonging to the scope of the idea of the present disclosure.

G Scissors gear 1 Main gear 2 Sub gear 4 Gear fitting surface 6 Ring plate 8 Spring 10 Boss 24 Ring fitting surface 25 Step surface

Claims (4)

A main gear having a cylindrical boss on the inner periphery;
A sub-gear fitted to the boss so as to be relatively rotatable,
A spring that urges the sub-gear in the circumferential direction with respect to the main gear;
A positioning member for positioning the sub-gear in the axial direction;
With
The scissors gear, wherein the positioning member is formed by a ring plate fixed to the boss. The boss has a gear fitting surface for fitting the sub-gear, and a ring fitting surface axially adjacent to the gear fitting surface,
The scissors gear according to claim 1, wherein the ring plate is fitted and fixed to the ring fitting surface. The ring fitting surface has a smaller diameter than the gear fitting surface, and a step surface extending in the radial direction is provided between the gear fitting surface and the ring fitting surface, and the step surface is the gear fitting surface. The ring plate is disposed flush with an end face of the sub gear fitted to the sub gear, and the ring plate is slidably contacted with the sub gear and fitted and fixed to the ring fitting surface in a state of contacting the step surface. The scissors gear according to claim 2. The scissors gear according to claim 2 or 3, wherein the ring plate is shrink-fitted to the ring fitting surface.

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