EP0806270A1

EP0806270A1 - Torque adjuster

Info

Publication number: EP0806270A1
Application number: EP96107304A
Authority: EP
Inventors: Ho-Tien Chen
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-02-06
Filing date: 1996-05-09
Publication date: 1997-11-12
Also published as: JPH09216125A; JP2707438B2

Abstract

A torque adjuster comprising a shaft (5), a shaft sleeve (1), two gear discs (2,3), a middle spring (4), an adjuster base (7), a rear spring (8), a front spring (9), a rear sleeve (6), a middle sleeve (10), a driver tip base (11), a bolt (12), a driver tip (13) and a front sleeve (14) as components, engagement force of the two gear discs being adjusted by the middle spring pushed by the adjuster base, which is able to adjust its force against the middle spring so that the torque of the shaft, combined with the driver tip base holding the driver tip, may be adjusted to prevent the torque adjuster form moving forward or backward in operation.

Description

Background Of the Invention

This invention concerns a torque adjuster, particularly one able to be prevented from moving forward or backward in case of too large a torque.
Conventional torque adjusters for pneumatic or electric electric screw drivers rotate smoothly in the beginning of driving a bolt or a screw, not moving forward or backward. But they have two gears engaging with each other, and two springs respectively pushed by the two gears to transmit torque to a driver tip, and will move forward or backward because of this kind of structure, lowering force in driving a screw or a bolt and lacking in operational exactness.
In addition, as a screw or a bolt is being driven more and more deeply, and the torque is also growing larger and larger,the driver tip will also move forward or backward as the two gears do. Then the driver tip becomes in loose contact with the screw groove of the screw or the bolt, resulting in friction between the screw and the driver tip and wear and tear of the driver tip caused by the friction.

Summary Of The Invention

An object of this invention is or offer a torque adjuster for a pneumatic of an electric screw driver, able to adjust the torque in the best way to prevent it from moving forward and backward in driving a screw of a bolt.
One of the feature of this present invention is a shaft transmitting rotation structured as integral so as to keep tight condition between the driver tip and a screw or a bolt being driven, preventing this adjuster from moving forward and backward even when the torque is the largest.
Another feature of the present invention is possibility in swift alteration of torque and changing the length of a driver tip being extended out.

Brief Description Of Drawings

Figure 1 is an exploded perspective view of a torque adjuster in the present invention.
Figure 2 is a perspective view of the torque adjuster in the present invention.
Figure 3 is a cross-sectional view of the torque adjuster in the present invention.
Figure 4 is a cross-sectional view of the torque adjuster in the present invention, showing its torque being adjusted.
Figure 5 is a cross-sectional view of the torque adjuster in the present invention, showing a driver tip being changed.
Figure 6 is a cross-sectional view of the torque adjuster in the present invention, showing length of a driver tip being adjusted.
Figure 7 is an upside view of a gear disc in the torque adjuster in the present invention.
Figure 8 is a cross-sectional view of line 7 - 7 in Fig. 7.
Figure 9 is a side view of the torque adjuuster in the present invention, showing it being in practical use.

Detailed Description Of The Invention

A torque adjuster in the present invention, as shown in Fig. 1, comprises a shaft sleeve 1, a front gear disc 2, a rear gear disc 3, a middle spring 4, a shaft 5, a rear sleeve 6, an adjuster base 7, a rear spring 8, a front spring 9, a middle sleeve 10, a driver tip base 11, a bolt 12, a driver tip 13, and a front sleeve 14 as components combined together.
The shaft sleeve 1 has a center hollow apace 15, a driver tip base hole 16 of a small diameter in the fornt portion of the hollow space 15, a female thread 17 in an inner surface a little behind the hollow space 15, a large flange 27 at a rear end, a plurality of curved notches 28 around the flange 27 for pins 32 to fit therein, and a small flange 29 at a front end outside of the driver tip base hole 16 for the front spring 9 to fit around.
The front gear disc 2 has a center hexagonal hole 18(or any geometrical hole but a circle), a plurality of teeth 20 on a rear end surface, each tooth having a vertical face 23 and a curved face 24. The rear gear disc 3 also has a center hexagonal hole 19 and a plurality of teeth 21 on a front end surface, and each tooth also having a vertical face 23 and a curved face 24 so that engagement of the two gear discs 2 and 3 enable this torque adjuster change rotating force of the driver tip 13 in accordance with driving depth of a screw of a bolt being driven. The center hole 18 and 19 of the front and the rear gear disc 2 and 3 can fit respectively with the end 25 of the driver tip base 11 the front end of the shaft 5.
The middle spring 4 fits around the front end of the shaft 5, interposed between the front end of the adjuster base 7 and the rear end of the rear gear disc 3. Then pushing force of the middle spring 4 against the rear gear disc 3 can be changed by adjusting the adjsuter base 7, and consequently engaging condition of the two gear discs 2 and 3 is also changed, to a resultant torque alteration.
The rear sleeve 6, fitting around the rear portion of the shaft sleeve 1, has an inner annular surface 30 at a front end for the front end of the rear spring 8 to rest on, and the rear spring 8 fits around the shaft sleeve 1, with its rear end resting against an inner end surface of the flange 27 of the shaft sleeve 1. The rear sleeve 6 also has one of more pin holes 31 for one or more pins 32 to fit in, in the curved notch(es) 28 and also in one or more pin slots 33 of the adjuster base 7, being securely combined with the shaft sleeve 1 and the adjuster base 7.
The adjuster base 7 has a larger diameter portion 34 than the rest portion, a male thread on the large diameter portion 34 to engage with the female thread 17 of the shaft sleeve 1, one or more pin slots 33 for the pin(s) 32 to fit and move therein, and a center hole for the shaft 5 to fit through. In case that torque of the torque adjuster is to be changed, as shown in Fig. 4, the rear sleeve 6 is pulled backward, letting the pin(s) 32 move back, and then manuslly rotated, letting the pin(s) 32 rotate the adjuster base 7 together with the rear sleeve 6, and altering pushing force of the spring 4 and consequently altering the torque.
The shaft 5 has a female-threaded hole 37 in a front end, two annular shallow grooves 38A spaced apart around a rear portion, which is to be pinched by a front end B of an electric screw driver A so that the shaft 5 may be rotated by the screw driver A.
The driver tip base 11 has a male-threaded large diameter portion 38 at a front end, an inter mediate portion 39,two opposite lengthwise recesses 40 in the threaded portion 38, a bead hole 41 in the intermediate portion 39 for a bead 42 to fit therein as shown if Fig. 3, a center hole 43 for the bolt 12 to fit therein and engage the female-threaded hole 37 of the shaft 5, and a center hexagonal hole 50 in the front end for the driver tip 13 to fit therein.
The bolt 12 has a threaded rear end to engage the threaded hole 37 of the shaft 5, after the bolt 12 is fitted through the driver tip base 11, and combining the shaft 5 with the drier tip base 11 as integral.
The front spring 9 is fitted around the driver tip base 11 and located in the middle sleeve 10, having a resilience to recover its position after the middle sleeve 10 is pulled back, as shown ins Fig. 5, and in addition, a function for easily changing a driver tip 13.
The middle sleeve 10 is pratly fitted around the shaft sleeve 1 so as to move in a definite direction, having a hollow space 44 for receiving the front spring 9, an inner annular surface 45 for one end of the front spring 9 to rest on, two guide shafts 46 extending lengthwise forward form a front end to fit in the recesses 40 of the driver tip base 11 and guide recesses 47 of the front sleeve 14 after the middle sleeve 10 is fitted around the driver tip base 11. Then the driver tip base 11, the front sleeve 14 and the middle sleeve 10 are combined in a definite direction. An inward protruding annular edge 45 abuts the inner annular surface 45 and forms a small space 49 itself and the two guide shafts 46, pressing down the bead 42 to fit in and annular groove in the driver tip 13 so that the driver tip may be firmly secured when the driver tip 13 is inserted in the driver tip base 11. But then the middle sleeve 10 is pulled backward, the bead 42 can ba led in the small space 49 to let loose the driver tip 13, which then becomes releasable.
The front sleeve 14 has an female thread 51 in a rear end engaging the male thread 38 of the driver tip base 11, and two opposite recesses 47 for the two opposite guide shafts 46 of the driver tip base 11 to fit therein.
As the male thread 38 of the driver tip base 11, engages the female thread 51 of the front sleeve 14, rotation of the front sleeve 14 relative to the driver tip base 11 can change length of the driver tip 13 protruding out of the front end of the front sleeve 14 so as to correspond to length of a screw of a bolt to be driven.
The outer shape of the driver tip 13 can be made to conform to the shape of the inner hole 50 of the driver tip base 11 so as to let the both to rotate synchronously.

Claims

A torque adjuster comprising:
a shaft sleeve having a center hollow space for receiving a front gear disc, a rear gear disc and a middle spring therein, a female thread in a rear ene of the center hollow space engaging a male thread of a adjuster base described later, said front and other and a center hole for a driver tip base and a shaft described later to fit therein, said front and said rear gear disc being rotated by the shaft;

a shaft having a front end fitting in the center hole of the rear gear disc, and a femasle thread in a front end engaging a male thread of a bolt of a driver tip base descrinbed later;

a rear sleeve having an inner annular surface for the front end of a rear spring to rest on, one or more lateral pin holes for one or more pins to fit therein and in one or more pin slots of an adjuster base, said rear spring having a rear end resting on a front end surface of a flange of said shaft sleeve,

an adjuster base having a front larger diameter portion than a rear portion, a center hole for said shaft to fit through, said front larger diameter portion having a male thread engaging the female thread of said shaft sleeve so the said adjuster base may be rotated to alter pressing force of the middle spring;

a driver tip base having a center hole for a bolt to fit through and engage the female-threaded hole of said shaft to let said adjuster tip base combined with said shaft as integral, a front larger diameter portion provided with a male thread enaging a front sleeve described later, an intermediate portion provided with a bead hole for a bead to fit therein, said larger diameter portion having a plurality of lengthwise recesses for guide shafts of a middle sleeve described later to fit therein:

a middle sleeve having a center hole for receiving a front spring therein fitting around said driver tip base, one or more guide shafts fitting in the recesses of said driver tip base and the recesses of a front sleeve described later;

a fornt sleeve having a female thread engaging the male thread of said driver tip base, and one or more guide recesses for the guide shafts of said middle sleeve to fit therein; and
characterized by said shaft fitted in the center hole of said rear gear disc, by said driver tip base fitted in the center hole of said front gear disc, said bolt combining said shaft with said driver tip base as integral to rotate together, said middle spring having its resilient force of pushing said rear gear disc adjusted by said adjuster base, permitting said shaft, said driver tip base and said driver tip secruied to rotate all torgeher but not move at random respectively.
The torque adjuster as claimed in Claim 1, wherein said larger diameter portion of said shaft sleeve has a plurality of curved notches around its end for said pins to fit therein, securing said rear sleeve with said shaft sleeve, preventing said rear sleeve from rotationg independently at random.
The torque adjuster as claimed in Claim 1, wherein said center holes of said front and said gear disc are shaped hexagonal.
The torque adjuster as claimed in Claim 1, wherein said driver tip base has its rear end shaped the same as said center hole of said front gear disc, and said shaft has its fornt end shaped the same as said center hole of said rear gear disc.