JPS5828045A - Planetary gear speed change device with torque limiter - Google Patents

Abstract

PURPOSE:To reduce weight of a device and form the device to small size while increase its mechanical efficiency, by holding an internal gear of a planetary gear mechanism through friction and integrally forming a limit switch actuating cam to the peripheral surface of said internal gear. CONSTITUTION:A load is rapidly increased, if torque reaction force, transmitted to the second sun gear 7, is increased to overcome maximum friction force of a disc brake, the second sun gear 7 begins to rotate shifting in an opposite direction to the first sun gear 3. If the second sun gear 7 rotates about 1/2 turn, an eccentric cam 7N also rotates synchronously, to open or close one limit switch 14 while close or open the other limit switch 14 reversely. Since the limit switch 14 is connected to the relay of an electric motor 2, at this point of time, a power source of the electric motor 2 is disconnected to stop the electric motor 2.

Description

[Detailed Description of the Invention] The present invention relates to a planetary gear reduction device with a torque limiter,
More specifically, the present invention relates to a planetary gear reduction device with a torque limiter that is compact, has excellent controllability, and prevents overload idling.

Conventionally, various torque limiters have been used to prevent electric motors from burning out due to overload rotation or stoppage. Furthermore, electric motors with reduction gears using worm gears, spur gears, or planetary gears are often used to obtain strong torque.

However, in the past, the torque limiter and the speed reducer were manufactured separately, and they were rarely used in optimal matching with each other, and a dimensionally compact combination was not necessarily obtained.

Conventionally, compactness has been inconvenient because it is essential for portable applications such as screwdrivers and applications such as valve opening/closing devices where external dimensions are limited.

In particular, a type of conventional torque limiter called a so-called speotorque limiting shaft joint is generally used.
This tended to result in a large external dimension compared to the transmitted torque U, and the mechanism for preventing overload slipping had to rely on a separate electric circuit, which resulted in a complicated structure. Therefore, the inventors of the present invention came up with the idea of adding a torque limiting function to the planetary gear reduction device by improving it itself, and as a result of various experiments and prototypes, they arrived at the present invention.

An object of the present invention is to provide a planetary gear reduction device with a torque limiter that is lightweight, compact, and operates reliably.

Another object of the present invention is to provide a planetary gear reduction device with a torque limiter that can limit torque and prevent overload idling.

According to the present invention, a $1 sun gear, a plurality of planet gears that mesh with the first sun gear, a planet carrier that also serves as a power take-off portion that integrally supports the plurality of planet gears, and a planet carrier that meshes with the planet gears. a second sun gear with a brake, and a second sun gear with a brake;
A planetary gear reduction gear with a torque limiter is provided, which includes a cam fixed to a sun gear, and a limit switch that is turned on and off by a follower that slides on the outer periphery of the cam.

The present invention will be described in detail below using examples.

FIG. 1 is a front sectional view of an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line l-H' in FIG.

As shown in FIGS. 1 and 2, an electric motor 2 is fixed to a frame 1 with bolts 21. As shown in FIGS. Further, a first sun float 3 is fixed to the light width of the output shaft 2A of the electric motor 2.

In FIG. 1, a plurality of planetary gears 4 are radially meshed with the outside of the first sun gear 3, and these planetary gears 4 are integrally pivotally supported by a planetary carrier 5. The planet carrier 5 also has a pair of ball bearings 8A, 8.
f, (one side is pivotally connected to the receiving plate 10 and the other side is pivotally connected to the second sun gear 7.The shaft portion of the planetary carrier 5 on the left receiving plate 10 side forms the output shaft of the planetary gear reduction device. ,
A hexagonal nut hole 5A for power extraction is drilled. The second sun gear 7 is a type of internal gear having a gear 7G on its inner diameter, a plurality of planetary gears 4 are meshed with the inner diameter, and the outer diameter is slidably rotatable by the frame 1. Fitted and supported.

Further, the output shaft of the electric motor 2 is pivotally supported on the inner diameter of the right end portion of the second sun gear 7 via a ball bearing 9. In addition, a flange is attached to the left end of the second sun gear 7.
It functions as the disc 7B of the disc brake. A pair of brake pads 11 and 11 are arranged on the disc 7B so as to press it from both sides, and the brake pad 1
The pressing force applied to the disk 7B of the first disc 7B can be adjusted by an adjustment screw 13 via a disc spring 12. Furthermore, as shown in FIGS. 1 and 2, the neck from the right side of the second sun gear 7 constitutes an eccentric cam 7N, and a follower (cam follower) 16 passing through a hole bored in the frame 1 is moved by a spring 15. It is in sliding contact with the outer periphery of the eccentric cam 7N. The outer end of follower 16 contacts actuator 14A of limit switch 14. It is desirable that two followers 16 and limit switches 14 be provided symmetrically as shown in FIG. Also, limit switch? Reference numeral 14 denotes a power switch for the electric motor 2 itself or an excitation power switch for the power switch. It is of course possible to replace the disc brake with a drum brake, hand brake, etc.

The above is the structure of the embodiment of the present invention.
Explain the effect.

During normal operation, the second sun gear 7 is braked and remains stationary until the torque reaction force reaches the maximum frictional force between the brake pad 11 and the disc 7B. Therefore, the torque of the output shaft 2A of the electric motor is transmitted to the plurality of planetary gears 4, but since the inner diameter gear 70 of the second sun gear 7 is stationary as described above, the planetary gear 4 is transmitted to the first sun gear 3. The planet carrier 5 rotates in the opposite direction, resulting in the planet carrier 5 being decelerated and turning around in the same direction as the first sun gear 3 . This is a normal power transmission state, and the transmission mechanical efficiency is higher than that of a worm gear mechanism or the like.

However, when the load suddenly increases and the torque reaction force transmitted to the second sun gear 7 overcomes the maximum frictional force of the disc brake braking force, the second sun gear 7 shifts in the opposite direction to the first sun gear 3. and start rotating. When the second sun gear 7 rotates approximately %, the eccentric cam 7N also rotates synchronously, opening or closing one limit switch 14, and conversely closing or opening the other limit switch 14.

As described above, the limit switch 14 is connected to the relay of the electric motor 2, so at this point the power to the electric motor 2 is turned off and the electric motor 2 is stopped. Therefore, the electric motor and the speed reduction mechanism are not continuously overloaded. Conversely, when viewed from the secondary output shaft (power take-off portion) 5A, no rotational force exceeding a certain torque is applied. Furthermore, the set torque can be easily adjusted using the adjustment screw 13. Therefore, the torque limiter of the present invention not only protects the electric motor, but also functions as a torque wrench. In other words, it can also be used to tighten bolts, nuts, screws, etc. with a preset constant torque.

The purpose of providing two limit switches 14 is to facilitate restarting the electric motor. By carrying out the present invention described in more detail, the following effects can be obtained.

(1,) A reduction gear with a torque limiter 7- can be obtained which is lightweight, compact and has high mechanical efficiency.

(21) Therefore, it is suitable for use as a portable torque driver or valve switch.

(3) Adjustment of torque setting is easy.

(4) Overload idling can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of an embodiment of the present invention, and FIG. 2 is a sectional view taken along line n-n' in FIG. 1... Frame, 2... Electric motor. 3...--First sun gear, 4...-Idle F gear. 5... Planet carrier, 7... Second sun gear. 8.9...Ball bearing, 10...Brace plate. ]1...Brake pad, 13...Adjustment screw. 14...Limit switch, 1 (Bi...subordinate)
section.

Claims (1)

[Scope of Claims] (1) A first sun gear, a plurality of planetary gears that mesh with the first sun gear, and a planetary carrier that also serves as a power extraction part that integrally supports the plurality of planetary gears. , a second sun gear with a brake that meshes with the planetary gear, a cam that is fixed to the second sun gear with a brake, and a limit switch that is switched on and off by a follower that slides on the outer periphery of the cam. An apparatus according to claim 1. (3) The device according to any one of claims 1 to 2, wherein the cam is an eccentric wheel.