JPH0318142Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial field of application] This invention provides that when a power tool is rotating in the forward direction,
Relating to an automatic reduction ratio switching device for power tools that automatically switches a reduction mechanism to a low reduction ratio or a high reduction ratio according to the load, and automatically switches the reduction mechanism to a high reduction ratio when the power tool is rotated in reverse. It is something.

[Conventional technology]

Conventional power tools, especially nut runners used for tightening and loosening bolts and nuts used in structures, are designed to shorten the tightening time when tightening bolts and nuts. Until they make contact, the bolts and nuts are rotated under low load at high speed, and when the bolts and nuts come into contact with the structure, they are rotated under high load at low speed and tightened so that the axial force of the bolt reaches the specified value. .

[The problem that the idea aims to solve]

However, when loosening bolts and nuts, it is necessary to apply a high load to the bolts and nuts from the beginning by rotating the output shaft in the opposite direction to when tightening the bolts and nuts.

Therefore, conventionally, two types of nut runners were prepared, one for tightening bolts and nuts, and one for loosening bolts and nuts, or two types of prime movers, one for high-speed, low-load use and one for low-speed, high-load use, were incorporated into one nut runner. Therefore, it was necessary to switch between two types of prime movers depending on the work conditions for tightening or loosening bolts and nuts.

Therefore, the former requires two nut runners, and the latter requires two prime movers, making the power tool large and heavy, making it difficult to operate and reducing work efficiency in both cases. However, there were also drawbacks such as the power tools becoming expensive.

The present invention was made to eliminate the above-mentioned drawbacks, and is incorporated into a power tool having a single prime mover, so that when the power tool rotates in the forward direction, it automatically reduces the reduction ratio to a low reduction ratio according to the load. When the high reduction ratio is switched and the rotation is reversed, the system automatically switches to the high reduction ratio, eliminating the need to use two types of power tools and eliminating the need for two prime movers. To provide an automatic reduction ratio switching device for a power tool, which can reduce the size and weight of the tool, improve operability, improve work efficiency, and provide an inexpensive power tool.

[Means to solve the problem]

In order to solve the above problems, the present invention provides an automatic reduction ratio switching device built into the gear case of a power tool. A drive shaft that is rotatably connected to the prime mover side and has a sun gear on the other end, a planetary gear that meshes with the sun gear, and a planetary gear that rotatably supports the planetary gear so that the planetary gear rotates around the sun gear. A planetary gear support (hereinafter abbreviated as support) that is rotated while meshing with the planetary gear,
An internal gear with a pawl clutch on the top surface, a one-way clutch provided between the internal gear and the gear case, a torque clutch provided between the drive shaft and the support, and a threaded part fixed to the drive shaft and attached to the outer periphery. The threaded cylinder provided with a It has a pawl clutch that can engage with the pawl clutch, and the upper surface is composed of a spring and the lower surface is composed of a locking ring that engages with the spring.

The one-way clutch is provided on the outer periphery of the internal gear,
It consists of a plurality of notches consisting of a bottom surface and a vertical plane perpendicular to the bottom surface, and a spring and a steel ball housed in each of these notches.The steel balls are always in contact with the bottom surface of the notch and the inner surface of the gear case due to the spring. ing.

The torque clutch consists of a movable cam that engages a main body fixed to the drive shaft with a pin via a steel ball, a fixed cam provided on the top surface of the support, one end of which is connected to the internal top surface of the threaded cylinder, and the other end of which is connected to the internal top surface of the threaded cylinder. The object of the present invention is to provide an automatic reduction ratio switching device for a power tool, which is characterized by comprising a moving cam and an engaging spring.

[Effect]

EMBODIMENT OF THE INVENTION Below, one Example of this invention will be described in detail based on drawing.

FIG. 1 is a sectional front view of a main part of a power tool in which an automatic reduction ratio switching device for a power tool according to an embodiment of the present invention is incorporated into a power tool, and FIG. 2 is a sectional view taken along a line taken from FIG. 1.

In the figure, an automatic reduction ratio switching device 3 built in a gear case 2 of a power tool 1 has one end rotatably connected to the prime mover side of the power tool 1, and a drive shaft 5 with a sun gear 4 provided at the other end. , a planetary gear 6 that meshes with the sun gear 4, and a planetary gear support (hereinafter abbreviated as support) that rotatably supports the planetary gear 6 and makes the planetary gear 6 revolve around the sun gear 4 while rotating. ) 7, an internal gear 9 that meshes with the planetary gear 6 and has a pawl clutch 8 on its upper surface, and a one-way clutch 10 provided between the internal gear 9 and the gear case 2.
, a torque clutch 11 provided between the drive shaft 5 and the support 7, a threaded cylinder 13 fixed to the drive shaft 5 and provided with a threaded portion 12 on the outer periphery, and a threaded cylinder 13.
It is threadedly engaged with the threaded portion 12 of the gear case 2, and is fitted with the sliding key 14 fixed to the gear case 2, and moves along the sliding key 14 without rotating in the axial direction. Interlockable pawl clutch 1
5, a spring 16 provided between the top surface of the lock ring 17 and the drive mechanism of the power tool, and a spring 1 provided between the bottom surface of the lock ring 17 and the internal gear 9.
6'.

The one-way clutch 10, as shown in FIG.
It consists of a plurality of notches 20 provided on the outer periphery of the internal gear 9 and consisting of a bottom surface 18 and a vertical surface 19 perpendicular to the bottom surface 18, and a spring 21 and a steel ball 22 respectively housed in the notches 20. The steel ball 22 is always in contact with the bottom surface 18 of the notch 20 and the inner surface of the gear case 2 due to the spring 21.

Therefore, when the internal gear 9 rotates in the direction of the arrow 23, the steel balls 22 are pushed by the vertical surface 19 of the notch 20 via the spring 21 and move along the inner surface of the gear case 2 together with the internal gear 9. The internal gear 9 can rotate freely relative to the gear case 2.

However, when the internal gear 9 rotates in the direction opposite to the arrow 23, that is, in the direction of the arrow 24, the steel balls 22 fit into the bottom surface 18 of the notch 20 and the inner surface of the gear case 2 in a wedge shape, and the internal gear 9 is rotated into the gear case 2. fixed against the inner surface of the

The torque clutch 11 includes a moving cam 28 that engages a main body 26 fixed to the drive shaft 5 with a pin 25 via a steel ball 27, a fixed cam 29 provided on the upper surface of the support 7, and one end of which is a threaded cylinder. 13 and a spring 30 at the other end which engages the moving cam 28.

Then, the drive shaft 5 rotates forward (arrow 23 in Figure 2).
However, when the load acting on the support body 7 is smaller than a predetermined value, the movable cam 28 engages with the fixed cam 29 via the steel ball 27, the drive shaft 5 and the support body 7 are connected, and the support body 7 rotates forward at the same rotation speed as the drive shaft 5, and when the load acting on the support body 7 increases and reaches a predetermined value, the steel ball 27 moves along the fixed cam 29 while resisting the force of the spring 30. 28 and disengages the movable cam 28 from the fixed cam 29. Therefore, the drive shaft 5 and the support 7 are disconnected, and the internal gear 9 is fixed by the one-way clutch 10. , the support 7 is decelerated by a planetary gear mechanism 31 consisting of a sun gear 4, a planet gear 6, a support 7 and an internal gear 9.

Further, when the drive shaft 5 rotates in the opposite direction (arrow 24 in FIG. 2), the steel ball 27 moves upward together with the movable cam 28, the movable cam 28 and the fixed cam 29 do not engage, and the drive shaft 5 and the support body 7 It is configured so that it is not connected.

Note that the predetermined value of the load that releases the connection between the drive shaft 5 and the support body 7 when the above-mentioned drive shaft 5 is rotating in the forward direction can be adjusted by the spring 30.

Next, the operation of the automatic reduction ratio switching device 3 having the above configuration will be explained.

In the following explanation, the rotation direction of each rotating part is
When viewed from the direction of arrow A in Figure 1, right rotation (clockwise rotation) (arrow 23 in Figure 2) is forward rotation, and left rotation (counterclockwise rotation) (arrow 24 in Figure 2) is reverse rotation. do.

In addition, the threaded portion 12 on the outer periphery of the threaded cylinder 13 has
It is assumed that a right-hand thread is provided.

Now, if the drive shaft 5 rotates in the forward direction and the load acting on the support body 7 is smaller than a predetermined value, the drive shaft 5 and the support body 7 are connected via the torque clutch 11, and the support body 5 is connected to the drive shaft 7. Rotates forward at the same number of rotations. In this case, the locking ring 17 is screwed into the threaded portion 12 of the threaded cylinder 13 provided with a right-hand thread, and since the threaded cylinder 13 rotates forward together with the drive shaft 5, the locking ring 17 is attached to the slider fixed to the gear case 2. moves upward along the key 14 while resisting the force of the spring 16 and being pushed by the spring 16';
The pawl clutch 15 stops at a position where it does not engage with the pawl clutch 8 provided on the internal gear 9.

Further, in this case, since both the sun gear 4 and the support body 7 provided on the drive shaft 5 rotate in the forward direction at the same rotation speed, the internal gear 9 also rotates in the forward direction at the same rotation speed.

That is, since the internal gear 9 rotates at the same rotation speed as the sun gear 4 in the direction of the arrow 23 shown in FIG. It rotates in the normal direction together with the drive shaft 5 via the sun gear 4.

When the load acting on the forward rotating support body 7 increases and reaches a predetermined value, the torque clutch 11
As a result, the connection between the drive shaft 5 and the support body 7 is released,
The rotation of the drive shaft 5 is transmitted to the internal gear 9 via the sun gear 4, the planetary gears 6, and the support 7, and the internal gear 9 rotates in the opposite direction.

That is, the internal gear 9 rotates in the direction of arrow 24 shown in FIG.

Therefore, the one-way clutch 10 is operated and fixed to the gear case 2 of the internal gear 9, and the drive shaft 5 is fixed.
The rotation from is decelerated and transmitted to the support body 7 via the planetary gear mechanism 31 without changing the direction of rotation, and the support body 7 rotates at a deceleration rate.

Furthermore, when the drive shaft 5 is rotated in the reverse direction, the torque clutch 11 is not activated, the drive shaft 5 and the support body 7 are not connected, and the threaded cylinder 13 fixed to the drive shaft 5 is rotated in the reverse direction. The engaged locking ring 17 descends along the sliding key 14 while being pushed by the spring 16 and against the spring 16', and its pawl clutch 15 engages the pawl clutch 8 provided on the upper surface of the internal gear 9. The internal gear 9 is meshed with the gear case 2 to fix the internal gear 9 to the gear case 2.

Therefore, the rotation from the drive shaft 5 is decelerated and transmitted to the support body 7 via the planetary gear mechanism 31 without changing the direction of rotation, and the support body 5 is decelerated and rotated in the opposite direction.

[Effect of idea]

By incorporating the automatic reduction ratio switching device having the above structure and operation into a power tool, and using the support as the output shaft or connecting it to the output shaft via another reduction mechanism, the power tool can be operated correctly. When rotating, it can automatically switch between body reduction ratio and high reduction ratio according to the load acting on the output shaft.
When a power tool is rotated in the reverse direction, it automatically switches to a high reduction ratio at all times, so for example, if the automatic reduction ratio switching device of the present invention is used in a nut runner, one nut runner can tighten and loosen bolts and nuts. It can be carried out.

Furthermore, since it is not necessary to use two prime movers, the machine is small and lightweight, and has good operability, thus improving work efficiency.

Moreover, it has the advantage of being able to be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of the main part of the present invention, and FIG. 2 is a cross-sectional view taken from FIG. 1. DESCRIPTION OF SYMBOLS 1... Power tool, 2... Gear case, 3... Reduction ratio automatic switching device, 4... Sun gear, 5... Drive shaft, 6... Planet gear, 7... Planet gear support,
8, 15... pawl clutch, 9... internal gear, 10...
...One-way clutch, 11 ... Torque clutch, 1
3...Screw cylinder, 14...Sliding key, 16,1
6'... Spring, 17... Lock ring, 31...
Planetary gear mechanism.

Claims (1)

[Claims for Utility Model Registration] In an automatic reduction ratio switching device 3 built into the gear case 2 of the power tool 1, one end is rotatably connected to the prime mover side of the power tool 1, and a sun gear 4 is connected to the other end. A drive shaft 5 provided,
A planetary gear 6 that meshes with the sun gear 4; and a planetary gear support (hereinafter abbreviated as support) 7 that rotatably supports the planetary gear 6 and makes the planetary gear 6 revolve around the sun gear 4 while rotating. an internal gear 9 that meshes with the planetary gear 6 and has a pawl clutch 8 on its upper surface; a one-way clutch 10 provided between the internal gear 9 and the gear case 2; and an internal gear 9 provided between the drive shaft 5 and the support 7. The torque clutch 11 is fixed to the drive shaft 5 and has a threaded portion 12 on its outer periphery, and the threaded cylinder 13 is screwed into the threaded portion 12 of the threaded cylinder 13 and fitted into the sliding key 14 fixed to the gear case 2. A lock ring 17 moves along the sliding key 14 without rotating in the axial direction and forms a pawl clutch 15 at its lower end that can mesh with the pawl clutch 8 of the internal gear 9.
, a spring 16 provided between the top surface of the lock ring 17 and the drive mechanism of the power tool, and a spring 1 provided between the internal gear 9 on the bottom surface of the lock ring 17.
6', the one-way clutch 10 is provided on the outer periphery of the internal gear 9, and has a plurality of notches 20 each consisting of a bottom surface 18 and a vertical surface 19 perpendicular to the bottom surface 18; spring 21 and steel ball 2
2, the steel ball 22 is always in contact with the bottom surface 18 of the notch 20 and the inner surface of the gear case 2 by a spring 21, and the torque clutch 11 has a steel ball 22 attached to a main body 26 fixed to the drive shaft 5 by a pin 25. 27, a fixed cam 29 provided on the upper surface of the support 7, and a spring 30, one end of which engages with the inner upper surface of the threaded cylinder 13, and the other end of which engages with the movable cam 28. An automatic reduction ratio switching device for a power tool, characterized in that: