JP3337334B2 - Sector gear - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sector gear device which can be suitably implemented as a swing actuator.
More specifically, the present invention relates to a structure for preventing backlash of a sector gear meshing with a gear driven in rotation.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing a typical prior art sector gear device 1. As shown in FIG. In the sector gear device 1, a drive gear 4 is formed integrally with a drive shaft 3 which is an output shaft of a servomotor 2, and the drive gear 4 has a tooth portion 6 of a sector gear 5 as shown in FIG. Meshes. The fan-shaped tooth portion 5 is fixed to a driven shaft 9 having an axis 8 parallel to the axis 7 of the drive shaft 3 at an interval L1. The driven shaft 9 is disposed at two intervals in the direction of the axis 8. The housing 11 is rotatably supported around the axis 8 by bearings 10a and 10b. The servo motor 2 is fixed to the housing 11, so that the distance L 1 changes due to thermal expansion or thermal contraction of the housing 11. Housing 11
Is made of aluminum die-cast or synthetic resin in order to reduce the weight or cost of the material. The sector gear 5 is made of a material having a smaller linear expansion coefficient than that of the housing 11, for example, quenched steel.

In such prior art, the sector gear 5 and the housing 11 are made of different materials as described above, and therefore have different linear expansion coefficients.
1 contracts more than the sector gear 5 and the distance L1 becomes smaller, the contact pressure increases at the meshing portion 12 where the drive gear 4 and the sector gear 5 mesh, and the rotational friction force increases. When the temperature becomes high, the amount of expansion of the housing 11 is larger than that of the sector gear 5, so that the distance L1 increases,
As a result, the backlash increases, and the control accuracy of the driven shaft 9 decreases. In particular, when the driven shaft 9 is incorporated with a servo-system power transmission mechanism to control the position of the driven member, it causes vibration. As described above, in this prior art, even when the sector gear 5 thermally contracts due to a temperature change, the linear expansion coefficient is considerably smaller than that of the aluminum alloy or the synthetic resin. There is a problem that can not be. This has made it difficult to reduce the weight and material cost.

FIG. 5 shows another prior art sector gear train 13.
FIG. 1 is a cross-sectional view showing the prior art.
9-109765. The sector gear device 13 is an oscillating actuator implemented in a so-called power window mechanism for vertically displacing a window glass of an automobile by a motor. The rotation of the motor 14 is transmitted to a pinion shaft 16 as a drive shaft via a speed reducer 15, and a pinion 17 as a drive gear is fixed to the pinion shaft 16. A sector gear 18 meshes with the pinion 17, and the sector gear 18 is fixed to a lever 19, and the lever 19 is a shaft 2 mounted on a base 20 as a housing.
1 so that the window glass can be displaced up and down by the lever 19. With only such a configuration, the sector gear 8 and the pinion 17
In this prior art, a cylindrical boss 23 having an eccentric fitting hole 22 is fitted into the base 20, and the motor 14 is fitted with the cylindrical boss 2.
3 is provided with a cylindrical boss 24 fitted into the fitting hole 22 of
The backlash is eliminated by rotating the cylindrical boss 23. With such a configuration, the sector gear 18, the lever 19 and the housing 20
Even if it is manufactured at low cost and therefore with low processing accuracy, the structure is such that the boss 23 can be rotated and adjusted to a state where backlash is eliminated. Not. Therefore, this prior art cannot eliminate backlash. Moreover, after the backlash has increased to some extent, the cylindrical boss 23 is rotated to adjust the gap between the sector gear 18 and the pinion 17 to be small, so that the backlash can be continuously maintained. Therefore, there is a problem that stable rotation characteristics of the sector gear 18 and the lever 19 cannot be obtained.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a sector gear device capable of continuously maintaining a backlash-free state and obtaining stable rotation characteristics over a wide temperature range regardless of the material used. It is to provide.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a drive shaft and a driven shaft whose respective axes are arranged in parallel at a fixed distance from each other are rotatable about the respective axes in a housing made of a rigid material. The driven shaft is supported, a sector gear is fixed to the driven shaft, and the drive shaft is provided with a drive gear meshing with the sector gear, and the rotational force of the drive shaft is transmitted to the driven shaft via the drive gear and the sector gear. In the sector gear device, the sector gear is fixed to the tooth portion on which the teeth meshing with the driving gear are formed, and is perpendicular to the tangent to the pitch circle at the center position of the tooth row of the tooth portion. A shaft portion extending in the axial direction, a boss portion fixed to the driven shaft and having a shaft hole into which the shaft portion is inserted, and a spring for urging the shaft portion radially outward with respect to the driven shaft. And a sector gear device comprising:

[0007]

According to the present invention, the drive shaft and the driven shaft are rotatably supported on the housing made of the rigid material with the respective axes parallel to each other and at a predetermined interval. A sector gear is fixed to the driven shaft, and a drive gear is fixed to the drive shaft.These drive gears mesh with the sector gear, and the rotational force of the drive shaft is driven via the drive gear and the sector gear. Transmitted to the shaft.

[0008] In such a sector gear device, the sector gear includes teeth, a shaft, a boss, and a spring. The teeth mesh with a drive gear. The shaft portion extends in the axial direction perpendicular to the tangent of the pitch circle at the center position of the tooth row of the tooth portion, and is fixed to the tooth portion. The boss has a shaft hole into which the shaft is inserted, and is fixed to a driven shaft. The spring resiliently biases the shaft portion radially outward with respect to the driven shaft. With such a spring, the tooth portion is kept in a state of constantly pressing the drive gear in a state of being meshed with the drive gear, whereby even if the housing thermally expands or contracts due to a temperature change, a dimensional change occurs. ,
Following the dimensional change of the housing, the tooth portion can be kept in contact with the drive gear at a substantially constant contact pressure, thereby preventing the occurrence of backlash. Moreover, since the tooth portion is always kept pressed against the drive gear by the spring, even if the distance between the axes of the drive shaft and the driven shaft greatly changes, it can be absorbed by the spring, This makes it possible to obtain stable rotation characteristics over a wide temperature range. Further, as described above, even if the distance between the axes greatly changes, it can be absorbed by the spring, so that the processing and assembling accuracy can be reduced, and even if thermal expansion or contraction does not matter, the parts and assembly costs can be reduced. I can do it.

[0009]

FIG. 1 shows a sector gear 31 of an embodiment of the present invention.
FIG. 2 is a sectional view taken along line II-II of FIG.
It is sectional drawing seen from. In FIG. 2, the housing 37 is omitted. The sector gear device 31 used as a swing actuator is basically a servo motor 3
2, a drive gear 34 integrally formed with an output shaft 33 which is a drive shaft of the servo motor 32, a sector gear 35 meshing with the drive gear 34, and a swing which is a driven shaft to which the sector gear 35 is fixed. It includes a shaft 36 and a housing 37 that supports the servomotor 32, the sector gear 35 and the swing shaft 36.

The axis 38 of the output shaft 33 of the servomotor 32 has an interval L2 with the axis 39 of the swing shaft 36, and is arranged parallel to each other. The swing shaft 36 is rotatably supported by the housing 37 around the axis 39 by a pair of bearings 40a and 40b arranged at intervals in the direction of the axis 39. Each of the bearings 40a and 40b may use, for example, an angular ball bearing.

The housing 37 is made of a magnesium alloy and has a linear expansion coefficient K1 = 26 × 10 ^-6 / ° C.
It is. The housing 37 has a substantially flat base 41.
And a rising portion 42 which rises from one side of the base 41 at a substantially right angle and rises, and a bent portion 43 which extends from an upper portion of the rising portion 42 and extends substantially parallel to the base 41. The base 41 has an output shaft 33 of the servomotor 32.
Is formed, and the bent portion 43 is closer to the rising portion 42 than the insertion hole 44 is.
The fitting hole 4 into which the one bearing 40b fits
5b is formed. The output shaft 33 is inserted into the insertion hole 44, and the periphery of the servomotor 32 is partially fitted into the insertion hole 44. In this state, the servomotor 32 is fixed to the base 41 by a plurality of screws 46. Bend 43
Has another fitting hole 4 coaxially with the fitting hole 45b.
The bearing 40a is formed in the fitting hole 45a.
Is stuck. In this way, the axis 37 of the output shaft 33 and the axis 39 of the swing shaft 36 are supported by the housing 37 in parallel with a certain interval L2. Here, each axis 38,
The fact that the distance L2 of the 39 is constant means that the housing 3
7 indicates the distance between the axis 38 and the axis 39 ignoring the influence of the thermal contraction.

The sector gear 35 is formed integrally with a tooth portion 49 meshing with the drive gear 34 and an axis perpendicular to the tangent to the pitch circle 51 at the center position of the tooth row 50 of the tooth portion 49. A shaft portion 53 extending in the 52 direction, a boss portion 55 fixed to the swing shaft 36 and having a shaft hole 54 into which the shaft portion 53 is inserted, and a shaft portion 54 housed in the shaft hole 54 to swing the shaft portion 53 And a compression coil spring 56 that is a spring that resiliently biases the shaft 36 radially outward. The tooth portion 49 extends over the same angle θ1, θ2 on both sides with respect to the central axis 52, and each angle θ1, θ2 is selected, for example, to 15 °.

The teeth 49, the shaft 53 and the boss 55
Is made of quenched steel, and the housing 3
7 is made of a material having a smaller coefficient of linear expansion. The compression coil spring 56 is made of, for example, spring steel. Further, a compression coil spring 56 made of stainless steel may be used instead of the spring steel.

The boss portion 55 has a circular cross section perpendicular to the axis 52, and has a base end portion 58 fixed to the swing shaft 36 and a radially outward portion connected to the base end portion 58, A cross section perpendicular to the axis has an annular cylindrical portion 59. An air vent hole 57 communicating with the shaft hole 54 is formed in the cylindrical portion 59. One end of the compression coil spring 56 is supported in contact with a bearing surface 60 in the shaft hole 54, and the other end is formed on an end surface 61 of the shaft portion 53 inserted into the shaft hole 54, which faces the spring receiving surface 60. It is abuttingly supported. A projection 62 is formed on the end face 61 to prevent the other end of the compression coil spring 56 from shifting. The spring force of the compression coil spring 56 is selected to be, for example, about 0.5 to 3 kgf.
In this embodiment, when the operating temperature range of the device 31 is + 45 ° C. to −30 ° C. at the interval L2 = 44 mm, the linear expansion coefficient of the steel constituting the sector gear 35 is 11.7 × 10 ^−6.
/ ° C, the module of the tooth portion 49 is m = 0.5 mm, the output torque of the servomotor 32 is T = 3 kgf · cm, the spring force of the compression coil spring 56 is F = 2.0 kgf, and the shaft portion 5
3 and the boss 55 are set to a clearance δ of about 10 μ.

In this case, the temperature range Δ of the sector gear 35
T is ΔT = + 45 − (− 30) = 75 ° C. (1), and the dimensional change ΔL1 of the sector gear 35 is ΔL1 = K1 · L2 · ΔT = 11.7 × 10 ⁻⁶ × 44 × 75 0.039 mm (2) Further, the dimensional change ΔL2 of the housing 37 is as follows: ΔL2 = K2 · L2 · ΔT = 26 × 10 ⁻⁶ × 44 × 75 ≒ 0.086 mm (3) When the backlash is set to be zero at a temperature of + 45 ° C. At a temperature of -30 ° C., a dimensional change ΔL1-ΔL2 between the sector gear 35 and the housing 37 occurs at −47 μm. However, the compression coil spring 56 absorbs the dimensional change, and the tooth portion 49 34 with a substantially constant contact pressure.

On the other hand, at a temperature of -30.degree.
When the temperature is set to 45 ° C., ΔL1 to ΔL
2 = 47μ, causing a large backlash,
By the action of the compression coil spring 56, the tooth portion 49 is pressed against the drive gear 34 with a substantially constant contact pressure also in this case.

As another embodiment of the present invention, the housing 37 is made of a light metal such as aluminum alloy or modified polyphenylene oxide (abbreviated modified PPO);
Mold molding may be performed using a thermoplastic resin such as modified polyphenylene ether (abbreviated modified PPE) or polycarbonate (abbreviated PC). Drive gear 3
The output shaft 4 and the output shaft 33 may be formed separately and fixed to each other.

As still another embodiment of the present invention, instead of the compression coil spring 56, a shaft portion 53 between a cylindrical portion 59 and a tooth portion 49 has a similar shape as shown by an imaginary line 56a in FIG. A compression coil spring may be provided.

[0019]

As described above, according to the present invention, the tooth portion is maintained in a state in which the drive gear is always pressed while being engaged with the drive gear, so that the housing is thermally expanded or expanded with the temperature change. Even if the housing shrinks to cause a dimensional change, the tooth portion can be kept in contact with the drive gear with a substantially constant contact pressure following the dimensional change of the housing, thereby preventing occurrence of backlash. be able to.
Moreover, since the tooth portion is always kept pressed against the drive gear by the spring, even if the distance between the axes of the drive shaft and the driven shaft greatly changes, it can be absorbed by the spring, This makes it possible to obtain stable rotation characteristics over a wide temperature range.

Further, since the gap between the axes can be absorbed by the spring, the processing accuracy and the assembly accuracy of the parts can be reduced, and the cost can be reduced even when thermal expansion or contraction does not matter.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a sector gear device 31 according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II in FIG.

3 is a cross-sectional view showing a typical prior art sector gear device 1. FIG.

4 is a partial perspective view showing a meshing state between the sector gear 5 and the driving gear 4 shown in FIG.

FIG. 5 is a cross-sectional view showing another prior art sector gear device 13;

[Explanation of symbols]

 Reference Signs List 31 sector gear device 32 servo motor 33 output shaft 34 drive gear 35 sector gear 36 swing shaft 37 housing 38, 39 axis 49 tooth portion 50 tooth row 51 pitch circle 53 shaft portion 54 shaft hole 55 boss portion 56 compression coil spring 60 spring Receiving surface 65 Thermal expansion material

Continuation of the front page (56) References JP-A-49-109765 (JP, A) JP-A-53-107553 (JP, A) JP-A-60-256671 (JP, A) JP-A-1-281282 (JP) , A) Fully open 51-160783 (JP, U) Fully open 60-139955 (JP, U) Fully open 1962-138951 (JP, U) Fully open 1962-169881 (JP, U) Fully open 63-11273 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16H 27/08 F16H 55/18 F16H 55/26

Claims (1)

(57) [Claims] A drive shaft and a driven shaft having respective axes arranged in parallel at a fixed interval from each other are rotatably supported around the respective axes by a housing made of a rigid material, and the driven shaft has , The sector gear is fixed, and the drive shaft,
In a sector gear device in which a driving gear meshed with a sector gear is provided, and a rotational force of a driving shaft is transmitted to the driven shaft via the driving gear and the sector gear, the sector gear is formed with teeth meshing with the driving gear. And a shaft fixed to the tooth and extending in the axial direction perpendicular to the tangent to the pitch circle at the center position of the tooth row of the tooth, and fixed to the driven shaft, and the shaft is inserted. A sector gear device comprising: a boss portion having a shaft hole; and a spring for urging the shaft portion radially outward with respect to a driven shaft.