JPH0783293A - Differential star gear device - Google Patents

Abstract

PURPOSE:To increase the gear reduction ratio in a small size by providing two sets of sun gears in parallel to an input shaft, making the star gears engaged with the sun gears also in two sets, providing rotatable one set of outer wheel gear whose inner teeth are engaged to the outer side of the star gears, and making the speed reduction ratio through the star gears a little different. CONSTITUTION:When an input shaft 1a is rotated, star gears 14a, 14b... and an outer wheel gear 12 are rotated in the directions of arrows. As a result, star gears 15a, 15b... are also rotated in the directions of arrows. By the difference of the diameters of the gears, the rotating speed of the gears 15a, 15b... is made a little slower than that of the star gears 14a, 14b.... Consequently, an output rotary shaft 4a is rotated through a substrate 9 and a U-shaped rotor 8 at a rotating speed corresponding to the difference of the rotating speeds of the star gears. Since the smaller the difference of the numbers of teeth of the star gears 14a, 14b..., and the star gears 15a, 15b..., the larger the speed reduction ratio, a large reduction ratio can be obtained by a simple structure, and since the number of the gears is few, the efficiency is improved, the noise is reduced, and a small size and a light weight are realized.

Description

Detailed Description of the Invention

[0001]

[Industrial application] This is used when a small size and a large reduction ratio are required. For example, it can be used as a drive device for a caster of an electric carrier.

[0002]

2. Description of the Related Art In a caster for an electric carrier, an electric motor mounted on the caster is decelerated by a reduction gear to a position of 1/50 to 1/100. Because the caster has a small diameter,
The rotary shaft of the electric motor, the input / output rotary shaft of the reduction gear, and the rotary shaft of the caster are coaxially arranged. Therefore, the reduction gear is configured by combining a plurality of planetary gear devices (referred to as star gear devices in this specification) to increase the reduction ratio. Therefore, there is a problem that it is large and expensive.

[0003]

Since the input and output shafts are coaxial, the star gear is the optimum speed reducing means, but a plurality of star gear devices are used to increase the speed reduction ratio. There is a problem that it becomes large and expensive and the frequency of failures increases. There is also a problem of increasing noise. The device of the present invention solves the above-mentioned problems by deforming one star gear to obtain a large reduction ratio.

[0004]

Means for Solving the Problems First means, first and second sun gears arranged side by side on an input shaft and fixed, and rotatably held outside the input shaft about the input shaft for synchronous rotation. An outer ring gear having first and second inner gears, a device for rotatably supporting the input shaft by a bearing provided in the outer casing, and a first sun gear and a first outer ring gear having the same diameter that mesh with each other. A plurality of first star gears, a device that rotatably supports the respective rotation shafts of the star gears by bearings provided on the side surface of the outer casing, and the second sun gear and the second outer ring gear mesh with each other. At the same time, a plurality of second star gears having the same diameter as the first star gear and different diameters, a device for rotatably supporting the respective rotation shafts of the star gears by bearings provided on the substrate, and the substrate are provided. Rotatably support the input shaft and rotate the substrate. With an output shaft that leads to the opposite side of the input shaft. Second Means In the first means, the inner gears of the first and second outer ring gears are made different in diameter, or the first and second sun gears are made different in diameter. Third Means In the first means, the rotating shaft of the electric motor is used as an input shaft and the rotating shaft of the caster is used as an output shaft.

[0005]

The outer gear of the star gear device is commonly used, and the outer gear is driven through two sets of sun gears and star gears having slightly different gear ratios depending on the input shaft. One set of rotating shafts of the above two sets of star gears is attached to the outer casing, and rotation about the input shaft of the other set of star gears is taken out as rotation of the output shaft. Therefore, since an operation similar to the well-known principle of a differential gear can be obtained, it is possible to obtain a star gear device having a large reduction gear ratio with a small size and light weight while suppressing noise generation.

[0006]

Embodiments of the present invention will now be described with reference to the drawings. 1 is a side view showing the external appearance, FIG. 2 is an explanatory view of the internal configuration of FIG. 1, FIG. 3 is a plan view of only the star gear device, and FIG. 4 is a plan view of another embodiment of the star gear device. In FIG. 1, reference numeral 1 is a DC motor, and the rotating shaft 1a drives a device of the present invention whose outer casing is shown by reference numeral 2. The wheels 4 are attached to the bearings 5a and 5b at the lower ends of the U-shaped frames 3a and 3b.
The rotary shaft 4a is rotatably supported. Frame 3a,
The protrusion 3 at the upper end of 3b is threaded and screwed to the lower part of the electric carrier. Generally, a plurality of sets of the above-mentioned devices, ie, casters, are attached to the lower part of an electric transport vehicle, and the wheels are driven by an electric motor so as to travel.

By rotating the protrusion 3, the traveling direction can be changed. There are two types of means for changing the traveling direction, one that is performed manually and the other that is automated. Symbol 2
The device of the present invention is housed in the outer casing shown by. The details will be described with reference to FIG. In FIG. 2, only the right side portion of the electric motor 1 is shown, and a cup-shaped outer casing 1b is capped on the right end of the cylindrical outer casing. Reference numeral 18 denotes a ball bearing provided inside the outer casing 1b, and the rotating shaft 1a is rotatably supported by the ball bearing 18. The ball bearing at the left end of the rotary shaft 1a is omitted and not shown. The left end of the cylindrical outer casing 2 is attached to the outer casing 1b, and the right end of the outer casing 2 includes the frame 3 of FIG.
a is attached.

On the right side of the rotary shaft 1a, the sun gear 13a,
13b are juxtaposed and fixed. Star gears that mesh with the sun gear 13a are shown as 14a and 14c. There are four star gears, as will be described later in FIG. 3, but 2
The individual pieces are omitted and not shown. The rotating shaft of each star gear is a bearing mounted on the side surface of the outer casing 1b (dotted line symbol 17a,
17 c), which is rotatably supported. The other two star gears (indicated by symbols 14b and 14d in FIG. 3)
Has the same configuration. Outer ring gear 12 is ball bearing 1
2a is supported so as to be freely rotatable around the rotation shaft 1a, and the inner gear of the outer ring gear 12 is the star gear 1
4a, 14b, ... Two star gears 15a and 15c that mesh with the sun gear 13b and the outer ring gear are shown, but as shown in FIG. 3, there are four star gears 15a, 15b, 15c and 15d. . The diameter of the sun gear 13b is slightly smaller than the diameter of the sun gear 13a, and the diameters of the star gears 15a, 15b, ... Are slightly larger than the diameters of the star gears 14a, 14b ,.

The rotating shaft 1 of the star gears 15a, 15b, ...
Bearings 1a and 11c are provided on the substrate 9 (dotted lines 10a and 10c).
rotatably supported by (indicated by c). There are four star gears as shown in FIG. 3, but only two are shown in FIG. The central portion of the substrate 9 is movably supported by the rotating shaft 1a so as to be rotatable. The substrate 9 has a disc shape,
The end of the U-shaped rotor 8 is inserted into the hole of the substrate 9 so that the substrate 9 and the U-shaped rotor 8 rotate synchronously. The U-shaped rotor 8 is fixed to the left end of the rotary shaft 4a. As described above with reference to FIG. 1, the rotating shaft 4a is the rotating shaft of the wheel 4 and is rotatably supported by bearings 5a and 5b. The rotary shaft 4a serves as an output shaft, and the rotary shaft 1a serves as an input shaft.

Next, the characteristics of the operation of the device of the present invention will be described with reference to FIGS. FIG. 3 is a plan view of FIG. 2 seen from the direction of arrow A. When the input shaft 1a rotates, the star gears 14a, 14b, ... And the outer ring gear 12 correspondingly rotate in the direction of the arrow in FIG. Therefore, the star gears 15a, 15b, ... Also rotate in the arrow direction. Due to the difference in the diameter of each gear, the rotation speed of the star gears 15a, 15b, ...
14b, ... a little slower than that. Therefore, the output rotation shaft 4a rotates at the rotation speed corresponding to the difference in the rotation speeds of the star gears described above via the substrate 9 and the U-shaped rotor 8 of FIG. As can be understood from the above description, since it operates as a differential star gear device, there is an effect that a large reduction ratio can be obtained. By rotating the input shaft 1a in the forward and reverse directions,
The output shaft 4a correspondingly rotates in the forward and reverse directions. Star gear 14a,
.. and the star gears 15a, 15b, .. The smaller the difference in the number of teeth is, the larger the reduction ratio is. Therefore, a star gear device having a large reduction ratio can be obtained with a simple configuration. Since it has a small number of gears, it is efficient, has less noise, and is compact and lightweight.

The smaller the difference in the number of teeth between the star gears 14a, 14b, ... And the star gears 15a, 15b, .. .., the description indicates that the tooth pitches are the same. However, the present invention can be practiced even if the pitches of the two teeth are different. Radius of sun gear is r
₁ , the radius of the star gear is r ₂ , and the radius of the outer ring gear is R, the following equation holds. r ₁ + 2r ₂ = R (1) If the tooth pitch is d, and the number of teeth of each of the sun gear, star gear, and outer ring gear is n ₁ , n ₂ , N, then n ₁ d = 2πr ₁ (2) n ₂ d = 2πr ₂ (3) N d = 2πR (4) R obtained from equations (2), (3), and (4)
By substituting the equation (1) for ₁ , r ₂ , and R, n ₁ / 2π × d + 2n ₂ / 2π × d = N / 2π × d Therefore, the equation of n ₁ + 2n ₂ = N (5) is obtained. As can be understood from the above description, it is necessary to set the number of teeth that satisfies the relationship of Expression (5).

Another means for achieving the same purpose is shown in FIG. FIG. 4 is a view of FIG. 2 seen from the direction of arrow A. In FIG. 4, the sun gear has the same diameter, and both have the symbol 13
Indicated as. Star gear 4 meshes with one of these
, And four star gears meshing with the other one are shown as symbols 15a, 15b ,. The star gears 15a, 15b, ... Have a slightly larger diameter than the star gears 14a, 14b, .. Therefore, the diameters of the inner gears of the outer ring gears that mesh with them are correspondingly different. The inner gears are shown as 12a and 12b. As can be understood from the above structure, the operation and effect are similar to those of the previous embodiment.

[0013]

As compared with a well-known device having a large reduction ratio in which a plurality of star gear devices are arranged side by side, the device of the present invention has a simplified structure, produces less noise, and is a small reduction gear having a large reduction ratio with good efficiency. There is an effect that the device can be obtained.

[Brief description of drawings]

FIG. 1 is a side view of the appearance of a caster to which the device of the present invention is applied.

FIG. 2 is an explanatory diagram of an internal configuration of an outer casing 2 corresponding to the device of the present invention in FIG.

FIG. 3 is a plan view of FIG. 2 seen from the direction of arrow A.

FIG. 4 is a plan view of another embodiment of the device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1,1a Electric motor and its rotating shaft 2 Outer casing 3,3a, 3b of this invention apparatus Frame 4a which supports the wheel 4 Rotating shaft 5a of the wheel 4, 5b, 12a, 18 Bearing 1b Outer casing 13,13a, 13b Sun gear 14a , 14b, ..., 15a, 15b, ... Star gears 12, 12a, 12b Outer ring gears and their inner gears 16a, 16c, 11a, 11c Rotating shafts 17a, 17c, 10a, 10c Bearings 8 Co-type rotor 9 Substrate

Claims (3)

[Claims] 1. A first sun gear and a second sun gear fixed side by side with an input shaft, and first and second inner gears that are rotatably held outside the input shaft and are synchronously rotated. An outer ring gear, a device for rotatably supporting the input shaft by a bearing provided in the outer casing, and a plurality of first stars of the same diameter that mesh with the first sun gear and the first outer ring gear. A gear, a device for rotatably supporting the respective rotation shafts of the star gear by bearings provided on the side surface of the outer casing, a second sun gear and a second outer ring gear, and a first star gear and a diameter , A plurality of second star gears having the same diameter, and a device for rotatably supporting the respective rotation shafts of the star gears by bearings provided on the substrate, and the substrate being rotatable about the input shaft. Support the board and guide the rotation of the board to the opposite side of the input shaft. Differential star gear device characterized in that it further configured with an output shaft. 2. The structure according to claim 1, wherein the inner gears of the first and second outer ring gears have different diameters or the first and second sun gears have different diameters. Characteristic differential star gear device. 3. A differential star gear device according to claim 1, wherein the rotary shaft of the electric motor is an input shaft and the rotary shaft of the caster is an output shaft.