JP2009103279A - Gear device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear device having a scissors gear structure capable of suitably suppressing backlash regardless of the magnitude of drive reaction force generated between gears. <P>SOLUTION: In the gear device in which one main gear (10) is engaged with the other main gear (4), sub-gears (20) are provided on an end surface of one main gear in parallel, a first urging means (30) for urging the sub-gear in a rotation direction by an elastic member is provided between the one main gear and the sub-gear, and a second urging means (40) for urging the sub-gear in the rotation direction by an elastic member is provided while having a play θc of a predetermined amount θ' between one main gear and the sub-gear in the rotation direction such that the sub-gear forms a predetermined clearance θ between a tooth of the sub-gear and a tooth of the other main gear. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gear device, and more particularly to a scissors gear structure for suppressing backlash generated between gears in a gear train used for an engine, a transmission, or the like.

  In a series of gear trains used in vehicle engines and transmissions, for example, tooth surface separation and tooth surface collision between a drive gear and an idler gear, or between an idler gear and a driven gear, due to rotational fluctuations accompanying load fluctuations of transmitted power. That is, there is a problem that backlash occurs, and rattling by the backlash causes noise and deterioration of members.

Therefore, for example, side gears (sub-gears) are provided on both end faces of the reverse idler gear, biasing means for applying a twisting force in the rotational direction to each side gear is provided, the teeth of the drive gear are sandwiched by one side gear, and the other side gear is 2. Description of the Related Art There is known a transmission that has a so-called scissors gear structure that sandwiches the teeth of a driven gear and absorbs backlash (see Patent Document 1).
Japanese Utility Model Publication No. 4-97145

In the device disclosed in Patent Document 1, biasing means for applying a twisting force in the rotational direction to each side gear is provided. The biasing force necessary for the biasing means is mainly from the engine via the drive gear. It is determined appropriately based on the driving reaction force generated with respect to the input driving force, and is usually set to a constant torsional force (torsion spring force) as shown in Patent Document 1.
However, since the degree of engine load fluctuation or rotation fluctuation causing backlash changes according to the engine load or rotation speed, the driving reaction force fluctuates relatively greatly. If the torsional force of the urging means is constant as disclosed in No. 1, there is a possibility that the backlash cannot be properly suppressed over the entire operation region of the engine.

  That is, for example, when the urging force (spring force) necessary for the urging means is set according to the case where the engine is low load and low rotation and the driving reaction force is small, the engine is high load and high rotation In this case, the backlash cannot be suppressed sufficiently due to insufficient urging force, but if the engine is set to a high load and high rotation and the driving reaction force is large, the engine will be under low load and low rotation. In some cases, the biasing force becomes excessive, and the biasing force is too strong as a whole, and the tooth surface pressure increases, resulting in inferior durability and reliability of the device.

  The present invention has been made to solve such problems, and the object of the present invention is to have a scissor gear structure capable of appropriately suppressing backlash regardless of the magnitude of the driving reaction force generated between the gears. It is in providing a gear device.

  In order to achieve the above object, the gear device of claim 1 is one main gear rotatably connected to one rotating shaft, and rotatably connected to another rotating shaft, and meshes with the one main gear. The other main gear and a sub-gear provided in parallel with the same number of teeth and the same tooth shape so as to be coaxially and relatively rotatable with the other main gear so as to mesh with the other main gear on the end surface of the one main gear; A first urging means provided between one main gear and the sub gear, for urging the sub gear with respect to the one main gear in a rotational direction by an elastic member; and the sub gear includes a tooth of the sub gear and the other gear. A predetermined amount of play is provided in the rotational direction between the one main gear and the sub gear so as to form a predetermined gap between the teeth of the main gear, and the play is packed. Characterized in that the sub gear and a second biasing means for biasing the same rotational direction as said first biasing means by the elastic member to the main gear of the one with.

  According to a second aspect of the present invention, in the gear device according to the first aspect, the elastic member is a coil spring, and the first urging means and the second urging means are respectively the sub gears of the one main gear. The coil spring extends in the circumferential direction between a main gear side stopper member provided on the side and a sub gear side stopper member provided on the one main gear side of the sub gear, and the second biasing means Has the play in the rotational direction between the main gear side stopper member and the coil spring or between the sub gear side stopper member and the coil spring.

According to a third aspect of the present invention, in the gear device according to the second aspect, the coil spring is embedded in an opening hole formed in either one of the one main gear and the sub gear.
According to a fourth aspect of the present invention, in the gear device according to any one of the first to third aspects, the predetermined gap is larger than a maximum backlash dimension between the teeth of the one main gear and the teeth of the other main gear. It is small.

  According to a fifth aspect of the present invention, the urging force of the elastic member of the second urging means is greater than the urging force of the elastic member of the first urging means. It is characterized by that.

  According to the first aspect of the present invention, the sub-gear is provided in parallel on the end surface of the one main gear, and the first urging means for urging the sub-gear in the rotational direction by the elastic member is provided between the one main gear and the sub-gear. In addition, the sub-gear has a predetermined amount of play in the rotational direction between the one main gear and the sub-gear so that the sub-gear forms a predetermined gap between the teeth of the sub-gear and the teeth of the other main gear. Since the second urging means for urging in the rotational direction is provided, when the teeth of one main gear mesh with the teeth of the other main gear, one main gear and the other according to the transmitted driving force In the range where the driving reaction force generated between the main gear and the main gear is small, the tooth of the other main gear and the tooth of the one main gear are subtracted while the driving reaction force is received by the elastic force of the first biasing means. The backlash between one main gear and the other main gear is satisfactorily eliminated, and the driving reaction force is increased so that the play in the rotational direction between the one main gear and the sub gear is eliminated. When packed, the other main gear teeth are sandwiched between the one main gear teeth and the sub gear teeth while receiving the driving reaction force by the resultant force of the first urging means and the second urging means. The backlash between one main gear and the other main gear is satisfactorily eliminated.

  That is, in the range where the driving reaction force generated between one main gear and the other main gear is small, the relatively small elastic force by the first urging means in accordance with the small driving reaction force causes the teeth of the one main gear and the sub gears to move. In the range in which the teeth sandwich the teeth of the other main gear and the driving reaction force is large, one of the first urging means and the second urging means is combined with the large driving reaction force with a strong elastic force. A scissors gear structure in which the teeth of the main gear and the teeth of the sub gear sandwich the teeth of the other main gear is exhibited by one sub gear. As a result, regardless of the magnitude of the driving reaction force generated between one main gear and the other main gear, the lack of elastic force and the urging with excessive elastic force are prevented, and the distance between one main gear and the other main gear is reduced. Can be adequately suppressed in two stages with a single sub-gear, which can effectively prevent noise and member deterioration due to gearing and maintain high durability and reliability of the gear device. Can do.

  Therefore, for example, when one main gear or the other main gear is a part of the engine or transmission gear train that transmits the driving force from the vehicle engine to the wheels, the scissors gear for preventing backlash with a simple configuration. The structure can be configured without excess or deficiency of the urging force, and it covers a wide range from the low driving reaction force situation where the engine is low load and low rotation to the high driving reaction force situation where the engine is high load and high rotation. Thus, the backlash between one main gear and the other main gear can be appropriately suppressed, and noise and deterioration of members can be satisfactorily prevented, and the durability and reliability of the engine and transmission can be maintained high.

  According to the gear device of the second aspect, the first urging means and the second urging means are respectively a main gear side stopper member provided on one main gear and a sub gear side stopper member provided on the sub gear. The second urging means has a play in the rotational direction between the main gear side stopper member and the coil spring or between the sub gear side stopper member and the coil spring. Therefore, the first urging means and the second urging means can be easily configured by using the coil spring, and the second urging means can easily play between the one main gear and the sub gear in the rotation direction. Can be provided.

According to the third aspect of the present invention, the coil spring is embedded in an opening hole formed in one of the one main gear and the sub gear, so that the coil spring can be compacted inside the one main gear or the sub gear. Can be stored.
Preferably, the coil spring is preferably embedded in an opening hole formed in one of the main gears, so that one of the main gears is configured to be thick while the sub gear is configured to be thin while preventing insufficient strength. can do.

  According to the gear device of the fourth aspect, since the predetermined gap is smaller than the maximum backlash dimension between the teeth of one main gear and the teeth of the other main gear, there is also a predetermined amount of play corresponding to the predetermined gap. Since the driving reaction force is smaller than the size corresponding to the maximum size of the backlash and the driving reaction force is relatively small, the driving reaction force is sufficiently obtained by the resultant force of the elastic force of the first urging means and the elastic force of the second urging means. The backlash between one main gear and the other main gear can be appropriately suppressed and sufficiently suppressed.

  According to the gear device of claim 5, since the biasing force of the elastic member by the second biasing means is larger than the biasing force of the elastic member by the first biasing means, it is excessive particularly when the driving reaction force is small. It is possible to prevent the biasing force from being biased and to prevent the biasing force from being insufficient when the driving reaction force is large, and it is possible to appropriately and reliably suppress the backlash between the one main gear and the other main gear. .

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Referring to FIG. 1, an external view of a main part of a gear device according to the present invention mounted on a vehicle is shown. Referring to FIG. 2, a longitudinal sectional view of the gear device of FIG. 1 is shown. FIG. 1 schematically shows a side view (a) viewed from the axial direction of the gear device of FIG. 1 and a top view (b) showing a meshing state. The configuration of the apparatus will be described.

  The gear device according to the present invention is, for example, a part of a gear train of a transmission (transmission) in which an input shaft is connected to an output shaft of an engine (not shown) and an output side is connected to wheels via an axle. . The transmission may be either a manual transmission (MT) or an automatic transmission (AT), but the transmission is well known, and the description of the entire configuration is omitted here.

  Specifically, the gear device according to the present invention includes, for example, a reverse gear (the other main gear) 4 that is slidably connected to the counter shaft 2 of the transmission, and an idler disposed in parallel with the counter shaft 2. It comprises an idler gear 8 that is fitted to a shaft 6 and meshes with the reverse gear 4. Although not shown here, a drive shaft for inputting a driving force from the engine is provided in parallel with the counter shaft 2, a drive gear is fitted to the drive shaft, and the drive gear is connected to the idler gear 8. Gears (both not shown) are also engaged. Thereby, for example, when the shift range of the transmission is in the forward position, the engine driving force causes the reverse gear 4 to idle from the drive gear through the idler gear 8, and the transmission shift range is switched to the reverse position (reverse range). When the reverse gear 4 is connected to the counter shaft 2, it is transmitted from the drive gear to the axle via the idler gear 8 and the reverse gear 4.

Here, the reverse gear 4 and the idler gear 8 are constituted by helical gears, whereby a smooth meshing between the reverse gear 4 and the idler gear 8 is realized.
By the way, the idler gear 8 has an idler gear main body (one main gear) 10 fitted to the idler shaft 6, and a thin sub-gear 20 is coaxial with the idler gear main body 10 and is rotatable relative to one end surface of the idler gear main body 10. The same number of teeth and the same tooth profile are provided in parallel. Specifically, the sub gear 20 is rotatably fitted to a boss on one end face side of the idler gear main body 10. Note that the axial shift of the sub gear 20 is restricted by a snap ring 22.

The idler gear main body 10 is provided with a main gear side stopper member 14 and a main gear side stopper member 16 projecting toward the sub gear 20 respectively, for example, on the same circumference and symmetrically about the axis about the axis. Similarly, the sub-gear-side stopper member 24 and the sub-gear-side stopper member 26 project from the idler gear body 10 respectively.
A coil spring (first biasing means) 30 is interposed between the main gear side stopper member 14 and the sub gear side stopper member 24, and between the main gear side stopper member 16 and the sub gear side stopper member 26. A coil spring (second urging means) 40 is interposed.

  Specifically, the idler gear main body 10 is provided with opening holes 12 and 13 for accommodating the coil springs 30 and 40, and the coil spring 30 is interposed between the main gear side stopper member 14 and the sub gear side stopper member 24. The coil spring 40 is embedded in and stored in the opening hole 13 while being interposed between the main gear side stopper member 16 and the sub gear side stopper member 26.

  That is, the coil springs 30 and 40 are interposed between the idler gear body 10 and the sub gear 20 through the main gear side stopper members 14 and 16 and the sub gear side stopper members 24 and 26 in a state of being accommodated in the opening holes 12 and 13. The sub gear 20 is urged in the rotational direction with respect to the idler gear main body 10 by at least one of the elastic force α of the coil spring 30 and the elastic force β of the coil spring 40.

That is, in the idler gear 8, a so-called scissor gear structure is constituted by the idler gear main body 10 and the sub gear 20, and therefore, when the idler gear main body 10 and the reverse gear 4 are engaged with each other, the idler gear 8 has the teeth 20a of the sub gear 20 engaged with the idler gear. The teeth 4 a of the reverse gear 4 are sandwiched between the teeth 10 a of the main body 10.
When the scissors gear structure is constituted by the idler gear main body 10 and the sub gear 20 in this manner, generally there is a gap between the teeth 10a of the idler gear main body 10 and the teeth 4a of the reverse gear 4, so that the transmitted driving force is transmitted. The driving reaction force generated between the reverse gear 4 and the idler gear 8 is fluctuated due to load fluctuation or rotation fluctuation accompanying the change, and tooth surface separation and tooth surface collision, that is, backlash occurs. Such backlash is caused by the scissor gear structure. Is well suppressed.

  Incidentally, as shown in FIG. 3, when the reverse gear 4 and the idler gear 8 are engaged with each other, the coil spring 30 is contracted between the main gear side stopper member 14 and the sub gear side stopper member 24, while the coil spring 40. Is loosely fitted between the main gear side stopper member 16 and the sub gear side stopper member 26, and has a play θc between the coil spring 40 and the sub gear side stopper member 26. That is, with respect to the coil spring 40, there is a play θc in the rotational direction between the idler gear body 10 and the sub gear 20.

Specifically, the coil spring 40, when viewed alone, has a clearance θ (predetermined clearance) between the teeth 20a of the sub gear 20 and the teeth 4a of the reverse gear 4 in a state where the reverse gear 4 and the idler gear 8 are engaged. ) And the play θc is set to a predetermined amount θ ′ corresponding to the clearance θ.
That is, when the teeth 20a of the sub gear 20 are engaged in the initial state, for example, when the reverse gear 4 and the idler gear 8 are engaged at a constant speed, as shown in FIG. The teeth 4a of the reverse gear 4 are sandwiched between the teeth 10a of the idler gear main body 10 by being biased by the coil spring 40 and the sub-gear-side stopper as shown in FIG. A play θc of a predetermined amount θ ′ is generated between the member 26 (θc = θ ′).

  Specifically, FIG. 3B shows the maximum backlash dimension δ (hereinafter referred to as backlash δ) generated between the teeth 4a of the reverse gear 4 and the teeth 10a of the idler gear body 10. The predetermined amount θ ′ is set so that the clearance θ is smaller than the backlash δ (θ <δ). According to experiments, the predetermined amount θ ′ is preferably set so that the clearance θ is, for example, 50% or less of the backlash δ.

The elastic force α of the coil spring 30 and the elastic force β of the coil spring 40 may be equal to each other, but here the elastic force β of the coil spring 40 is greater than the elastic force α of the coil spring 30. Thus, the spring constant of the coil spring 40 is set larger than the spring constant of the first coil spring 30.
The operation and effect of the gear device according to the present invention configured as described above will be described below.

  For example, when the reverse gear 4 and the idler gear 8 are meshed at a constant speed with a low load and a low rotation, the driving reaction force generated between the reverse gear 4 and the idler gear 8 is small without large load fluctuations and rotation fluctuations. As shown in FIG. 3B, the teeth 20 a of the sub gear 20 are urged by the elastic force α of the coil spring 30 and are in contact with the teeth 4 a of the reverse gear 4. That is, the teeth 4a of the reverse gear 4 are sandwiched by the elastic force α between the teeth 20a of the sub gear 20 and the teeth 10a of the idler gear body 10 forming a scissors gear structure. Thereby, the backlash between the reverse gear 4 and the idler gear 8 at a low load and a low rotation is satisfactorily suppressed.

  On the other hand, when the engine load and rotation speed change suddenly to become high load and high rotation, and the driving force input to the idler gear 8 fluctuates suddenly and a large load fluctuation or rotation fluctuation occurs, the reverse gear 4 and the idler gear 8 are The generated driving reaction force varies greatly. As a result, the teeth 20a of the sub gear 20 retreat against the elastic force α of the coil spring 30 by the driving reaction force, and backlash begins to occur between the reverse gear 4 and the idler gear 8.

  Then, referring to FIG. 4, when the teeth 20a of the sub gear 20 are retracted against the elastic force α of the coil spring 30 by the driving reaction force, they are meshed with the side view (a) viewed from the axial direction of the gear device. 3 is schematically shown in the same manner as FIG. 3, but the amount of backlash between the reverse gear 4 and the idler gear 8 reaches the clearance θ as shown in FIG. 4 (b) shows that the clearance generated between the teeth 4a of the reverse gear 4 on the front side of the teeth 10a of the idler gear body 10 reaches the clearance θ), that is, the coil spring 40 and the sub gear side stopper member 26. When the play θc between them is filled and eliminated (θc = 0), the teeth 20a of the sub gear 20 are urged by the elastic force β of the coil spring 40 in addition to the elastic force α of the coil spring 30. It will contact | abut with the tooth | gear 4a of the reverse gear 4. FIG. That is, when the play θc is filled and lost, the teeth 4a of the reverse gear 4 are sandwiched by the resultant force of the elastic force α and the elastic force β by the teeth 20a of the sub gear 20 and the teeth 10a of the idler gear body 10 forming the scissors gear structure. It is done. Thereby, even if the driving reaction force generated between the reverse gear 4 and the idler gear 8 changes greatly due to high load and high rotation, the backlash between the reverse gear 4 and the idler gear 8 is still well suppressed.

  As described above, in the gear device according to the present invention, the sub gear 20 that is urged by the elastic force α of the coil spring 30 and the elastic force β of the coil spring 40 is provided on the end surface of the idler gear body 10 in the idler gear 8. The coil spring 40 is provided with a play θc between the idler gear body 10 and the sub gear 20 so that the elastic force β acts only when the amount of backlash between the gear 4 and the idler gear 8 reaches the clearance θ. The scissors gear structure is configured in two stages.

  Thus, in a range where the driving reaction force generated between the reverse gear 4 and the idler gear 8 is small, the teeth 4a of the reverse gear 4 and the teeth 20a of the sub gear 20 and the idler gear body 10 are received while the driving reaction force is received by the elastic force α of the coil spring 30. As a result, the backlash between the reverse gear 4 and the idler gear 8 can be satisfactorily suppressed, and the driving reaction force is increased so that the play θc between the idler gear body 10 and the sub gear 20 is reduced. The teeth 4a of the reverse gear 4 are sandwiched between the teeth 20a of the sub gear 20 and the teeth 10a of the idler gear body 10 while receiving the driving reaction force by the resultant force of the elastic force α of the coil spring 30 and the elastic force β of the coil spring 40. Thus, the backlash between the reverse gear 4 and the idler gear 8 can be suppressed satisfactorily.

  Accordingly, the engine has a low load and a low load regardless of the magnitude of the driving reaction force generated between the reverse gear 4 and the idler gear 8 while having a simple configuration in which one sub-gear 20 is provided on one end face of the idler gear body 10. Energizing with insufficient or excessive elastic force over a wide range from low driving reaction force such as rotation to high load and high driving reaction force such as high rotation. The backlash between the reverse gear 4 and the idler gear 8 can be appropriately suppressed in two stages, noise and member deterioration due to gearing can be prevented well, and transmission durability and reliability are maintained high. can do.

  In particular, the coil spring 30 is used as the first biasing means, the coil spring 40 is used as the second biasing means, and there is a play θc between the sub-gear-side stopper member 26 and the coil spring 40. The biasing means and the second biasing means can be easily configured using the coil springs 30 and 40, and the play θc can be easily provided between the idler gear body 10 and the sub gear 20 in the second biasing means. .

  Further, since the coil springs 30 and 40 are respectively embedded and stored in the opening holes 12 and 13 formed in the idler gear main body 10, the coil springs 30 and 40 are stored compactly in the idler gear main body 10. Can be. Further, by embedding the coil springs 30 and 40 in the idler gear main body 10 side as described above, the idler gear main body 10 can be configured to be thick while the sub gear 20 can be configured to be thin while preventing insufficient strength.

  Further, by setting the predetermined amount θ ′ so that the clearance θ is smaller than the backlash δ (θ <δ), the driving reaction force is set to the elastic force α of the coil spring 30 from the stage where the driving reaction force is relatively small. It can be sufficiently received by the resultant force of the elastic force β of the coil spring 40, and the backlash between the reverse gear 4 and the idler gear 8 can be appropriately suppressed and sufficiently suppressed.

  Further, by setting the spring constant of the coil spring 40 to be larger than the spring constant of the coil spring 30 so that the elastic force β of the coil spring 40 is larger than the elastic force α of the coil spring 30, the engine has a low load. In addition, it is possible to prevent excessive urging force from being urged when the driving reaction force is low at low revolutions, and to ensure that the urging force is not insufficient when the engine is at high load and high rotation and the driving reaction force is large. Thus, the backlash between the reverse gear 4 and the idler gear 8 can be appropriately suppressed and reliably suppressed.

The description of one embodiment of the present invention is finished above, but the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, a play θc of a predetermined amount θ ′ is provided between the coil spring 40 and the sub gear side stopper member 26, but the play θc is determined between the coil spring 40 and the main gear side stopper member 16. It may be provided between the coil spring 40 and the sub gear side stopper member 26 and between the coil spring 40 and the main gear side stopper member 16.

Further, in the above embodiment, the opening holes 12 and 13 are formed in the idler gear main body 10 and the coil springs 30 and 40 are embedded and stored in the opening holes 12 and 13, respectively. Opening holes that can accommodate the coil springs 30 and 40 may be provided respectively, or the opening holes may not be provided.
In the above embodiment, the biasing means is configured by the coil spring 30 and the coil spring 40. However, the biasing means is not limited to the coil spring, and may be configured by a torsion spring or the like. One of the urging means may be constituted by a coil spring, and one of the other urging means may be constituted by a torsion spring or the like.

In the above-described embodiment, the biasing means is configured in two stages by the coil spring (first biasing means) 30 and the coil spring (second biasing means) 40. You may make it comprise a biasing means.
In the above-described embodiment, the coil spring 30 and the coil spring 40 are arranged, for example, point-symmetrically with respect to the axis on the same circumference. However, the present invention is not limited to this, and can be freely arranged in the circumferential direction. Even when the urging means is composed of three or more stages, the urging means may be provided radially on the same circumference, and is not limited thereto, and can be freely arranged in the circumferential direction. is there.

In the above embodiment, the case where the gear device is a part of the gear train of the transmission (transmission) has been described as an example. However, the present invention is not limited to this, and the gear device may be used as long as it has a backlash. May be part of the gear train of the engine or part of the gear train of other mechanisms.
Moreover, in the said embodiment, although the reverse gear 4 and the idler gear 8 are comprised with a helical gear, these may be a normal spur gear.

It is a principal part external view of the gear apparatus based on this invention mounted in the vehicle. It is a longitudinal cross-sectional view of the gear apparatus of FIG. It is a figure which represents typically the side view (a) seen from the axial direction of the gear apparatus of FIG. 1, and the upper view (b) which shows a meshing state. It is a figure which represents typically the side view (a) seen from the axial direction of the gear apparatus and the upper view (b) which shows a meshing state when the teeth of the sub gear are retracted by the driving reaction force.

Explanation of symbols

4 Reverse gear (the other main gear)
8 Idler gear 10 Idler gear body (one main gear)
12, 13 Opening holes 14, 16 Main gear side stopper member 20 Sub gear 24, 26 Sub gear side stopper member 30 Coil spring (first urging means)
40 Coil spring (second biasing means)

Claims (5)

One main gear rotatably connected to one rotating shaft;
The other main gear that is rotatably connected to the other rotating shaft and meshes with the one main gear;
A sub gear provided in parallel with the same number of teeth and the same tooth shape so as to be coaxially and relatively rotatable with the one main gear so as to mesh with the other main gear on the end surface of the one main gear;
A first urging means provided between the one main gear and the sub gear, and urging the sub gear with respect to the one main gear in the rotation direction by an elastic member;
The sub gear is provided with a predetermined amount of play in the rotational direction between the one main gear and the sub gear so as to form a predetermined gap between the teeth of the sub gear and the teeth of the other main gear; Second urging means for urging the sub gear with the elastic member in the same rotational direction as the first urging means when the play is packed;
A gear device comprising: The elastic member is a coil spring;
The first urging means and the second urging means are respectively a main gear side stopper member provided on the sub gear side of the one main gear and a sub gear side provided on the one main gear side of the sub gear. The coil spring is extended in the circumferential direction between the stopper member,
The second biasing means has the play in a rotation direction between the main gear side stopper member and the coil spring or between the sub gear side stopper member and the coil spring. The gear device according to 1.   The gear device according to claim 2, wherein the coil spring is embedded in an opening hole formed in one of the one main gear and the sub gear.   The gear device according to any one of claims 1 to 3, wherein the predetermined gap is smaller than a maximum backlash dimension between the teeth of the one main gear and the teeth of the other main gear.   5. The gear device according to claim 1, wherein an urging force of the elastic member of the second urging unit is larger than an urging force of the elastic member of the first urging unit.

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