JPH08189554A - Fan-shaped gear device - Google Patents

Abstract

PURPOSE: To attain a rotational characteristic of a driven gear which is stable in a wide temperature range by continuously eliminating the occurrence of a backlash. CONSTITUTION: A driving shaft 33 and a driven shaft 36 where the respective axes 38 and 39 are arranged in parallel to each other at specific intervals, are rotatably supported around the respective axes in a housing 42 composed of a rigid material, and a fan-shaped gear 35 is fixed to the driven shaft 36, and a driving gear 34 with which the fan shaped gear 35 meshes is arranged on the driving shaft 33, and torque of the driving shaft 33 is transmitted to the driven shaft 36 through the driving gear 34 and the fan-shape gear 35. The fan-shaped gear 35 is composed of a tooth part 49 having teeth to mesh with the driving gear 34, a shaft part 53 which is fixed to the tooth part 49 and extends in the direction of the axis 52 perpendicular to a tangent of a pitch circle in a central position of a tooth row of this tooth part 49, a boss part 55 which is fixed to the driven shaft 36 and has a shaft hole 54 into which the shaft part 53 is inserted and a spring 56 to energize the shaft part 53 outward in the radial direction to the driven shaft 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fan 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 fan gear that meshes with a gear that is rotationally driven.

[0002]

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

In such a prior art, the fan gear 5 and the housing 11 are made of different materials as described above, and therefore have different linear expansion coefficients, so that the housing 1 is low in temperature.
1 contracts more than the sector gear 5, and the interval L1 becomes smaller, the contact pressure becomes higher at the meshing portion 12 where the drive gear 4 and the sector gear 5 mesh, and the rotational friction force increases. Further, when the temperature becomes high, the expansion amount of the housing 11 becomes larger than that of the sector gear 5, so that the interval L1 increases,
As a result, backlash increases, and the control accuracy of the driven shaft 9 decreases. In particular, when a servo system power transmission mechanism is incorporated in the driven shaft 9 to control the position of the driven member, it causes vibration. As described above, in this prior art, even if the fan 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, so that the dimensional change of the housing 11 due to the temperature change can be followed. I have a problem that I can't. This makes it difficult to reduce the weight and cost of materials.

FIG. 5 shows another prior art fan gear 13.
FIG. 4 is a cross-sectional view showing the prior art, which is disclosed in, for example, Japanese Patent Laid-Open No.
No. 9-109765. This fan-shaped gear device 13 represents a swing actuator implemented in a so-called power window mechanism that vertically displaces a window glass of an automobile with a motor. The rotation of the motor 14 is transmitted to the pinion shaft 16 as a drive shaft via the reduction gear 15, and the pinion 17 as a drive gear is fixed to the pinion shaft 16. A fan gear 18 meshes with the pinion 17, the fan gear 18 is fixed to a lever 19, and the lever 19 is a shaft 2 planted in a base 20 as a housing.
The window 19 is pivotally supported by the lever 1, and the lever 19 allows the window glass to be vertically displaced. With such a structure alone, the fan gear 8 and the pinion 17 are
Therefore, 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 provided with the cylindrical boss 2
By providing a cylindrical boss 24 that fits into the fitting hole 22 of 3,
Backlash is eliminated by rotating the cylindrical boss 23. With such a configuration, the sector gear 18, the lever 19 and the housing 20 are provided.
Even if it is manufactured at a low cost and therefore with a low processing accuracy, the structure is such that the boss 23 can be rotated to adjust to a state in which backlash is eliminated, the material of each member is the same, and temperature change is a problem. I haven't. Therefore, this prior art cannot eliminate backlash. Moreover, after the backlash has increased to some extent, the cylindrical boss 23 is rotated to make an adjustment so that the gap between the sector gear 18 and the pinion 17 becomes smaller, so that the state in which the backlash is continuously eliminated can be maintained. However, there is a problem in that stable rotation characteristics of the sector gear 18 and the lever 19 cannot be obtained.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to continuously maintain a backlash-free state and obtain stable rotation characteristics in a wide temperature range regardless of the material used. Is to provide.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a drive shaft and a driven shaft whose axes are arranged in parallel with each other at a constant interval are rotatably rotatable about each axis in a housing made of a rigid material. A fan gear is supported on the driven shaft, and a drive gear with which the fan gear meshes is provided on the drive shaft, and the rotational force of the drive shaft is driven by the drive gear and the fan gear. In the fan gear device to be transmitted to, the fan gear is fixed to the tooth portion where the teeth meshing with the drive gear are formed, and is fixed to the tooth portion, and is perpendicular to the tangent line of the pitch circle at the center position of the tooth row of this 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 biasing the shaft portion radially outward with respect to the driven shaft. It is a fan gear device characterized by including and.

[0007]

According to the present invention, the drive shaft and the driven shaft are rotatably supported in the housing made of a rigid material so that their axes are parallel to each other and are spaced apart from each other by a predetermined distance. A fan gear is fixed to the driven shaft, and a drive gear is fixed to the drive shaft.The drive gear and the fan gear mesh with each other, and the rotational force of the drive shaft is driven by the drive gear and the fan gear. Transmitted to the shaft.

In such a fan gear device, the fan gear includes a tooth portion, a shaft portion, a boss portion, and a spring. The tooth portion meshes with the drive gear. The shaft portion extends in the axial direction perpendicular to the tangent to the pitch circle at the center position of the tooth row of the tooth portion and is fixed to the tooth portion. A shaft hole into which the shaft portion is inserted is formed in the boss portion and is fixed to the driven shaft. The spring elastically 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 being constantly pressed against the drive gear while being meshed with the drive gear, so that even if the housing is thermally expanded or contracted due to the temperature change, a dimensional change occurs. ,
It is possible to keep the tooth portion in contact with the drive gear at a substantially constant contact pressure by following the dimensional change of the housing, 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 in a wide temperature range. Further, as described above, even if the distance between the axes changes greatly, it can be absorbed by the spring, so that the precision of processing and assembly can be lowered, and even if thermal expansion and contraction are not a problem, the cost of parts and assembly can be reduced. Can be achieved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a fan gear device 31 according to an embodiment of the present invention.
2 is a cross-sectional view of FIG. 2, and FIG. 2 is a cross-sectional line II-II of FIG. 1.
It is sectional drawing seen from. The housing 37 is omitted in FIG. The fan gear device 31 used as the swing actuator is basically a servo motor 3
2, a drive gear 34 integrally formed with the output shaft 33 that is the drive shaft of the servomotor 32, a fan gear 35 that meshes with the drive gear 34, and a swing that is a driven shaft to which the fan gear 35 is fixed. It includes a shaft 36 and a housing 37 that supports the servomotor 32, the fan gear 35, and the swing shaft 36.

The axis 38 of the output shaft 33 of the servomotor 32 has a distance L2 from the axis 39 of the swing shaft 36 and is arranged in parallel with 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. The bearings 40a and 40b may be angular ball bearings, for example.

The housing 37 is made of magnesium alloy, and its linear expansion coefficient is K1 = 26 × 10 ^-6 / ° C.
Is. The housing 37 has a substantially flat base portion 41.
And a rising portion 42 which is bent upward from one side portion of the base portion 41 at a substantially right angle, and a bent portion 43 which is bent from the upper portion of the rising portion 42 and bent substantially parallel to the base portion 41. The base 41 has an output shaft 33 of the servo motor 32.
An insertion hole 44 is formed through which the through hole 44 is inserted, and the bent portion 43 is closer to the rising portion 42 than the insertion hole 44.
The fitting hole 4 into which the one bearing 40b is fitted below
5b is formed. The output shaft 33 is inserted into the insertion hole 44, and the peripheral portion of the servo motor 32 is partially fitted, and in this state, the servo motor 32 is fixed to the base portion 41 by a plurality of screws 46. Bent portion 43
The other fitting hole 4b coaxially with the fitting hole 45b.
5a is formed, and the bearing 40a is formed in the fitting hole 45a.
Fits in. In this way, the axis 38 of the output shaft 33 and the axis 39 of the swing shaft 36 are supported by the housing 37 in parallel with each other with a constant distance L2. Where each axis 38,
The distance L2 of 39 is constant means that the housing 3
7 refers to the distance between the axis 38 and the axis 39 ignoring the effect of heat shrinkage.

The fan-shaped gear 35 is integrally formed with a tooth portion 49 that meshes with the drive gear 34, and an axis line perpendicular to the tangent line of 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 boss portion 55 housed in the shaft hole 54 to swing the shaft portion 53. A compression coil spring 56, which is a spring that elastically biases the shaft 36 radially outward. The teeth 49 extend on both sides with respect to the central axis 52 at equal angles θ1 and θ2, and the angles θ1 and θ2 are selected to be 15 °, for example.

The tooth portion 49, the shaft portion 53 and the boss portion 55.
Is made of hardened steel, said housing 3
It is made of a material having a linear expansion coefficient smaller than 7. The compression coil spring 56 is made of, for example, spring steel. In addition to this spring steel, a compression coil spring 56 made of stainless steel may be used.

The boss 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 base end portion 58 extending radially outward from the base end portion 58. It has a tubular portion 59 whose cross section perpendicular to the axis is annular. 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 abuts against and is supported by the bearing surface 60 in the shaft hole 54, and the other end is on the end surface 61 of the shaft portion 53 inserted into the shaft hole 54, the end surface 61 facing the spring receiving surface 60. It is elastically abutted and supported. A projection 62 is formed on the end face 61 to prevent the other end of the compression coil spring 56 from being displaced. The spring force of such a 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 set to + 45 ° C. to −30 ° C. with the interval L2 = 44 mm, the linear expansion coefficient of steel forming the fan 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 servo motor 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 is
The clearance δ between 3 and the boss 55 is set to about 10 μ.

In this case, the temperature range Δ of the sector gear 35 is
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 ΔL2 = K2 · L2 · ΔT = 26 × 10 ⁻⁶ × 44 × 75 ≈0.086 mm (3), and the backlash is set to 0 at a temperature of + 45 ° C. At a temperature of -30 ° C., a difference ΔL1−ΔL2 in dimensional change between the fan gear 35 and the housing 37 will be −47 μ, but the compression coil spring 56 absorbs this difference in dimensional change, and the tooth portion 49 causes the drive gear to move. It is pressed against 34 with a substantially constant contact pressure.

On the contrary, the backlash is 0 at the temperature of -30 ° C.
If set so that ΔL1 to ΔL at a temperature of 45 ° C.
2 = 47μ, causing a large backlash,
Due to the action of the compression coil spring 56, the tooth portion 49 is also pressed against the drive gear 34 with a substantially constant contact pressure in this case as well.

In another embodiment of the present invention, the housing 37 is made of a light metal such as aluminum alloy or modified polyphenylene oxide (abbreviated as modified PPO).
Molding may be performed using a thermoplastic resin such as modified polyphenylene ether (abbreviation: modified PPE) or polycarbonate (abbreviation: PC). Also drive gear 3
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, the shaft portion 53 between the cylindrical portion 59 and the tooth portion 49 is similar to that shown by the phantom line 56a in FIG. A compression coil spring may be provided.

[0019]

As described above, according to the present invention, since the tooth portion is kept in the state of meshing with the drive gear and always pressing the drive gear, the housing is thermally expanded or expanded in accordance with the temperature change. Even if it contracts to cause a dimensional change, the tooth portion can be kept in contact with the drive gear at a substantially constant contact pressure by following the dimensional change of the housing, thereby preventing the 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 in a wide temperature range.

Further, since the gap between the axes can be absorbed by the spring, the machining accuracy and the assembly accuracy of the parts can be relaxed, and the cost can be reduced even when the thermal expansion and contraction are not a problem.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a fan 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.

FIG. 3 is a sectional view showing a typical prior art fan gear device 1.

FIG. 4 is a partial perspective view showing a meshed state of the sector gear 5 and the drive gear 4 shown in FIG.

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

[Explanation of symbols]

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

Claims (1)

[Claims] 1. A drive shaft and a driven shaft whose axes are arranged in parallel with each other at a constant distance from each other are rotatably supported by a housing made of a rigid material around the respective axes, and the driven shaft is provided on the driven shaft. , A sector gear is fixed, and the drive shaft is
In a fan gear device in which a drive gear with which a fan gear meshes is provided, and the rotational force of the drive shaft is transmitted to the driven shaft via the drive gear and the fan gear, the fan gear has teeth that mesh with the drive gear. And a shaft portion fixed to the tooth portion, extending in the axial direction perpendicular to the tangent to the pitch circle at the center position of the tooth row of the tooth portion, fixed to the driven shaft, and the shaft portion is inserted. A fan gear device comprising: a boss portion in which a shaft hole is formed; and a spring for urging the shaft portion radially outward with respect to the driven shaft.