JPH0713926Y2 - Power tool speed switching mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an improvement of a speed switching mechanism of an electric tool.

[Conventional technology]

FIG. 2 is a vertical sectional side view of a main part of a conventional electric power tool. In the figure, 1 is a motor shaft, 1a is a motor shaft gear, 2 is a gear 2a,
A transmission shaft that has a large gear 2b and a small gear 2c and transmits the rotation of a motor (not shown) to the output shaft 3. The gear 2a is a motor shaft gear 1a.
Is meshed with. Reference numeral 4 is a high speed gear, 5 is a low speed gear, which are rotatably supported by the output shaft 3, the high speed gear 4 is meshed with the large gear 2b, and the low speed gear 5 is meshed with the small gear 2c. . 6 is a shift knob, 7 is a clutch plate, and this clutch plate 7 is an outer peripheral portion of the shift knob 6
Is fitted to the protrusion 6a. Further, the clutch plate 7 engages with the spline portion 3a provided on the output shaft 3 and is axially moved by the rotation of the shift knob 6 so that the projections 7a and 7b provided on the side surface of the clutch plate 7 have high and low speed gears 4. The holes 4a and 5a formed in 5 are fitted together. Reference numerals 8 and 9 are compression coil springs provided on the outer surfaces of the high and low speed gears 4 and 5.

The operation will be described below. First, when the electric tool is set to "low speed", the shift knob 6 is rotated to shift the clutch plate 7 to the right side as shown in the figure, and the low speed gear 5 is locked to the output shaft 3. Let

The rotation of the motor shaft 1 is transmitted to the output shaft 3 via the small gear 2c, the low speed gear 5 and the clutch plate 7, and the output shaft 3
Rotates at low speed.

Next, in the case of "high speed", the shift knob 6 is rotated to shift the clutch plate 7 to the left side, and the high speed gear 4 is locked to the output shaft 3.

The rotation of the motor shaft 1 is transmitted to the output shaft 3 via the large gear 2b, the high speed gear 4 and the clutch plate 7, and the output shaft 3 rotates at high speed.

If the holes 4a and 5a of the high and low speed gears 4 and 5 and the projections 7a and 7b of the clutch plate 7 do not fit, the projections 7a and 7b
Presses the inner surfaces of the high and low speed gears 4 and 5, and the high and low speed gears 4 and 5 receive the reaction force of the compression coil springs 8 and 9. Therefore, when the motor shaft 1 starts to rotate, the clutch plate 7 is fitted into the holes 4a and 5a of the high and low speed gears 4 and 5,
Smooth speed switching can be performed by the constant meshing method.

[Problems to be solved by the device]

Conventionally, speed switching of electric power tools has been performed by selectively switching transmission to a plurality of gears that are constantly meshed provided on a transmission shaft and an output shaft. In order to increase the rotation ratio of the output shaft with respect to the rotation of the motor due to deceleration due to the meshing of gears, there is a drawback that the gear becomes large and becomes a large power tool in the radial direction. On the other hand, there is a planetary gear mechanism that can obtain a large reduction ratio in a small space, but it is difficult to change the speed by this mechanism itself, and the output shaft of the planetary gear mechanism is simply used as the transmission shaft. Even if the speed conversion mechanism as shown is adopted, it becomes a large power tool in the axial direction, and it has a drawback that it cannot be sufficiently downsized. An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and provide a compact power tool.

[Means for Solving the Problems]

The present invention has a gear holder to which the power of the planetary gear mechanism is transmitted by supporting the shaft of the planetary gear mechanism of the planetary gear mechanism, and the anti-planetary gear mechanism side of this gear holder is configured to have a smaller diameter than the planetary gear mechanism side. Further, the large diameter portion and the small diameter portion of the gear holder generated by such a structure are respectively made into a large gear and a small gear, and the large gear and the small gear are always meshed with the high speed gear and the low speed gear, respectively. It

[Action]

The present invention has a gear holder to which the power of the planetary gear mechanism is transmitted by supporting the shaft of the planetary gear mechanism of the planetary gear mechanism, and the anti-planetary gear mechanism side of this gear holder is configured to have a smaller diameter than the planetary gear mechanism side. Further, the large diameter portion and the small diameter portion of the gear holder, which are generated by such a configuration, are made as a large gear and a small gear, respectively, and the large gear and the small gear are constantly meshed with the high speed gear and the low speed gear, respectively, so that the planet Inevitably configured parts due to the characteristics of the gear mechanism (large diameter part and small diameter part)
Since it can be used as a gear, the power transmission mechanism from the motor to the output shaft can be downsized.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional side view of a main part of the electric power tool according to the present embodiment.

In the figure, 1 is a motor shaft, 2 is a transmission shaft, 3 is an output shaft,
The rotation of the motor shaft 1 is caused by the planetary gears 10 arranged on the motor shaft.
A large gear 11a (large diameter portion) and a small gear 11b (small diameter portion) formed on a gear holder 11 which is rotatably supported by a motor shaft and to which power is transmitted by a planetary gear 10, and a high speed gear 1 which meshes with this gear 1a.
2, low speed gear 13 and clutch mechanism 14 as an engaging member
The rotation of the transmission shaft 2 is transmitted to the transmission shaft 2 via a gear 2d formed on the transmission shaft 2, a gear 3b meshing with the gear 2d,
It is transmitted to the output shaft 3 via the clutch mechanism 18. By supporting the shaft of the planetary gear 10 rotated by the motor shaft 1, the anti-planetary gear mechanism side of the gear holder 11 to which the power of the planetary gear mechanism is transmitted has a smaller diameter than the planetary gear mechanism side. This gear holder caused by configuring
The large diameter portion and the small diameter portion of 11 are respectively a large gear 11a and a small gear 11b,
The large gear 11a and the small gear 11b always mesh with the high-speed gear 12 and the low-speed gear 13, respectively, so that the parts (large diameter portion and small diameter portion) inevitably formed on the characteristics of the planetary gear mechanism are geared. Therefore, the power transmission mechanism from the motor to the output shaft 3 can be downsized.

2e is a spline part provided on the transmission shaft 2, 15 is a spline part
It is a clutch plate that engages with 2e and is slidable in the axial direction. The high and low speed gears 12 and 13 are rotatably supported by the transmission shaft 2, the outer surfaces thereof are pressed by the compression coil springs 16 and 17, and the inner surfaces thereof are in contact with the spline portion 2e. Splines 12a and 13a are formed on the inner surfaces of the high and low speed gears 12 and 13 so as to be connected to the spline portion 2e, and form the gear locking portions of the high and low speed gears.

The operation will be described below. First, in the case of "high speed", the clutch plate 15 is moved to the left side of the spline portion 2e as shown in the drawing, and the high speed gear 12 is locked to the transmission shaft 2.

The rotation of the motor shaft 1 is transmitted to the transmission shaft 2 via the planetary gear 10, the large gear 11a, the high speed gear 12 and the clutch mechanism 14.

Next, in the case of "low speed", the clutch plate 15 is moved to the right side of the spline portion 2e, and the low speed gear 13 is locked to the transmission shaft 2.

The rotation of the motor shaft 1 is transmitted to the transmission shaft 2 via the planetary gear 10, the small gear 11b, the low speed gear 13 and the clutch mechanism 14.

Even when the high and low speed gears 12 and 13 are not smoothly engaged with the spline portion 2e, the repulsive force of the compression coil springs 16 and 17 shifts the engagement state when the motor shaft 1 rotates.

That is, the smooth speed switching function by the constant meshing system is maintained as in the case of the conventional technique.

In this embodiment, the clutch plate is attached to the spline portion 2e.
Although 15 is coupled, this coupling method can be a method of rotating integrally with the transmission shaft and being slidable in the axial direction, for example, a coupling by a key.

According to this embodiment, at the position close to the shaft center as described above, the side surface of the high / low speed gear is brought into contact with the spline portion provided on the transmission shaft, and further, the side surface of the high / low speed gear is connected to the spline portion. Since the gear locking portion is provided, the pressing force by the compression coil spring is applied from the side surface, and even if an eccentric load is applied to the low speed gear, the high speed and low speed gears do not easily fall, and therefore the large gear and The meshing with the small gears is smooth, noise can be reduced, and the service life can be extended.

[Effect of device]

The present invention has a gear holder to which the power of the planetary gear mechanism is transmitted by supporting the shaft of the planetary gear mechanism of the planetary gear mechanism,
The anti-planetary gear mechanism side of this gear holder is configured to have a smaller diameter than the planetary gear mechanism side, and the large diameter portion and the small diameter portion of this gear holder caused by such a configuration are designated as a large gear and a small gear, respectively. Since the small gears always mesh with the high speed gear and the low speed gear, respectively, a compact electric tool can be provided.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a main part of an electric power tool according to an embodiment of the present invention, and FIG. 2 is a vertical sectional side view of a main part of a conventional electric power tool. 1 is a motor shaft, 2 is a transmission shaft, 2e is a spline part, 3 is an output shaft, 10 is a planetary gear, 11 is a gear holder, 11a is a large gear, 1
1b is a small gear, 12 is a high speed gear, 12a and 13a are splines,
13 is a low speed gear, 14 is a clutch mechanism, 15 is a clutch plate, and 16 and 17 are compression coil springs.

Claims (2)

[Scope of utility model registration request] 1. A motor, a planetary gear mechanism for reducing the rotation of the motor, a high speed gear and a low speed gear to which power is transmitted from the planetary gear mechanism, and a high speed gear and a low speed gear. An electric motor including a transmission shaft that is freely supported, an engagement member that selectively transmits the power of the high-speed gear and the low-speed gear to the transmission shaft, and an output shaft to which power is transmitted from the transmission shaft. In the speed switching mechanism of the tool, the tool has a gear holder to which the power of the planetary gear mechanism is transmitted by supporting the shaft of the planetary gear mechanism of the planetary gear mechanism, and the side of the gear holder opposite to the planetary gear mechanism is the planetary gear mechanism side. The gear holder is configured to have a smaller diameter, and the large diameter portion and the small diameter portion of the gear holder generated by such a configuration are respectively a large gear and a small gear, and the large gear and the small gear are the high speed gear and the low speed gear, respectively. Specially designed to always mesh with gears Speed switching mechanism of the power tool to be. 2. The speed switching mechanism for an electric power tool according to claim 1, wherein the shaft of the motor and the output shaft are concentric with each other.