EP0019019B1

EP0019019B1 - Device for a torque wrench

Info

Publication number: EP0019019B1
Application number: EP79300809A
Authority: EP
Inventors: Lee Fu-Tsai
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-05-11
Filing date: 1979-05-11
Publication date: 1983-07-13
Also published as: DE19019T1; EP0019019A1; DE2965839D1; ATE4096T1

Abstract

The present invention relates to a device for coupling a torque handle (100, 200) to a socket and for limiting the torque applied to the socket by the handle characterised in that the device comprises a body (10) connectible to said handle and having a substantially cylindrical portion (11) at one end thereof; a torque limiting clutch (70) for transmitting torque from the handle to the socket; means (80) coupling the clutch (70) to the body (10) and applying force to the clutch to maintain the clutch in an engaged attitude; a housing (50) for said clutch (70), the housing being telescopically coupled to the body (10) such that rotation of the housing and the body relative to one another displaces the housing and the body towards or away from one another to adjust the force applied to the clutch by said means (80); and control means (30) movable between two positions, in a first of which said housing (50) and said body (10) are freely rotatable relative to one another and in the second of which positions said housing and said body are locked non-rotatable relative to one another.

Description

This invention relates to a device for a torque wrench for coupling a torque handle to a socket.
The conventional torque wrench is generally provided with no torque indicating means and is prone to distorting or breaking a nut of an article when the torsion applied thereto is too great. Conversely, the nut loosens and becomes insecure when the torque applied is insufficient. For example, spark plugs and various nuts and bolts used in automobiles and motorcycles, and fittings for home electrical appliances require tightening to a specific torque value.
One known type of torque wrench has an indicating disc on a handle thereof and an indicator on a rectangular plug thereof. However, it is considerably bulky and is inconvenient to use. In addition, it requires close attention to be paid to the indicating disc and the indicator thereof while being used to ensure that the desired torque is not exceeded. In this case, only a skilled operator can make good use of the torque wrench.
United States Patent Specification No. 3,889,490 describes a simple form of torque wrench which is locked by means of a screw. United States Patent Specification No. 3,001,430 describes a torque limiting screwdriver with a ball detent mechanism arranged to transmit the torque force.
An object of the present invention is to provide an improved socket joint for a torque wrench.
The present invention provides a torque limiting device for a socket wrench comprising a torque limiting clutch for transmitting torque from the socket wrench to a socket, the clutch comprising two frictionally engaged clutch members; resilient means applying force to one of the clutch members to maintain said clutch members in engagement with one another, said force being adjustable; control means movable between a first position wherein said force is fixed and a second position enabling adjustment of said force; a substantially tubular housing telescopically engaged in a substantially tubular portion of a body and containing said torque limiting clutch for transmitting torque from the socket wrench to a socket, one of the clutch members being adapted for engagement in the socket and the other being coupled to said body by way of said resilient means, whereby rotation of said housing relative to said body adjusts said force applied by said means characterised in that said body is connectible at its end remote from said housing to said socket wrench and said control means comprises a controlling ring coaxially surrounding said body and rotatable relative thereto between said first and second positions, at least one torque transmitting ball element movably disposed in a through-hole in the wall of said body tubular portion and having a dimension greater than the thickness of said wall so as to project from said throughhole; and wherein the housing has a plurality of recesses formed in its radially outer surface for partially receiving said torque transmitting ball element when said controlling ring is in said first position to prevent relative rotation of said housing and said body and said controlling ring has at least one recess formed in its radially inner surface for partially receiving said torque transmitting ball element when said controlling ring is in said second position to enable relative rotation of said housing and said body; and wherein said body tubular portion has an axial screw threaded member along which said housing is screwable by relative rotation of said body and said housing and said resilient means is a compression coil spring coupling said other clutch member to said screw threaded member.
The present invention is further described hereinafter, by way of example, with reference to the accompanying drawings; in which:

Figure 1 is an exploded perspective view showing a preferred embodiment of the present invention;
Figure 2 is a longitudinal section through the preferred embodiment of Fig. 1;
Figure 3 is a longitudinal section through a second embodiment according to the present invention;
Figure 4 is a perspective view showing a torque wrench embodying the device of this invention;
Figure 5 is a perspective view showing a further torque wrench embodying the device of this invention; and
Figure 6 is an exploded perspective view showing a second form of clutch for a joint according to this invention.

Figure 1 shows a preferred device according to this invention comprising a body 10, a bolt 20, a rectangular plug 60, a clutch housing in the form of a casing 50, a clutch 70, a spring 80, a compressing ring 40, a controlling ring 30 in the form of a sleeve-like member and a positioning nut 90.
The body 10 is in the form of a cylinder having a cylindrical portion or chamber 11 situated at its lower end as seen in Fig. 1 so as to receive the clutch casing 50. Situated adjacent the opposite, upper end of the chamber 11 is a screw-threaded axial blind bore 12 which engages with one end of the bolt 20. A plurality of small screw-threaded radial bores 13 is provided in the body 10 opening into the bore 12 for receiving screws 25 which secure the bolt 20 in position. A plurality of through holes 16 are provided in the wall 15 of the chamber 11 so as to receive a plurality torque transmitting elements in the form of balls 17 each having a diameter greater than the thickness of the wall 15 of the chamber 11. The upper end of the body 10 is provided with an axial socket 18 of rectangular cross-section so as to receive a rectangular plug of a torque wrench (not shown). The outer periphery of the body 10 is engraved with a plurality of lines 19 (Figs. 4 and 5) corresponding in number to recesses in the form of guiding flutes 53 of the clutch casing 50 and indicating lines and symbols 55 engraved on the outer wall of the casing 50.
One end of the bolt 20 engages in the bore 12 as described above; the other end thereof engages in a screw threaded axial bore 93 in the positioning nut 90.
The controlling ring 30 is a sleeve-like fit around the outer wall of the chamber 11 and at each end has a respective annular recess 31, 32 in the form of increased internal diameter portions so as to protect wholly the compressing ring 40 and the outer wall of the body 10 in part. A protruding pin 33 is provided on the controlling ring 30 and engages in an arcuate groove 42 in an upper surface 41 of the compressing ring 40 so that rotation of the controlling ring 30 relative to the ring 40 is limited. The outer wall of the controlling ring 30 is provided with an indicating means 34 (Figs. 4 and 5) showing the states of "ON" and "OFF" each of which can be brought into alignment with an arrow on the body 10 to indicate whether torsion is "ON" or "OFF". The inner wall 35 of the ring 30 is provided with a plurality of longitudinal grooves 36 to receive the balls 17. A slanting rim of each groove 36 facilitates insertion and removal of said balls 17.
The inner diameter of the compressing ring 40 is equal to the outer diameter of the wall 15 so that said compressing ring 40 is a tight fit over the body 10. The outer diameter of the ring 40 is somewhat smaller than inner diameter of the recess 32 of the ring 30 so as to enable the controlling ring 30 to rotate freely.
The clutch casing 50 is a hollow cylindrical tube provided with a radially inwardly directed annular flange 51 at a lower end of its inner wall to receive the rectangular plug 60 and clutch 70. The positioning nut 90 is secured to the clutch casing 50 by inserting one or more pins 95 through holes 52 and 92 in the casing 50 and positioning nut 90 respectively. The spring 80 is positioned between the bolt 20 and clutch 70. A plurality of guiding flutes 53 are provided on the outer wall of the casing 50 so as to partially receive the balls 17. A plurality of indicating lines and symbols 55 are engraved on the outer wall thereof to indicate the strength of the torque applied thereto.
The plug 60 rests against the protruding ring 51 with its rectangular portion projecting at one end and is designed to connect with a socket of an article. The other end of the plug 60 is formed as one clutch member 701 with teeth to engage with teeth 71 on a second clutch member 702.
The clutch members 701, 702 as shown in Figure 1 have symmetrical teeth.
Figure 6 shows a further preferred embodiment of the clutch; one contacting face thereof is provided with a plurality of protrusions 711 while another face thereof is provided with several cavities 712 corresponding to the protrusions 711. A locating means 72 is situated to position said spring 80 on the clutch.
The positioning nut 90 has a cylindrical outer wall 91 provided with two said circular holes 92 to enable it to be secured to the clutch casing 50 as described hereinbefore. The inner wall of the nut 90 is provided with the bore 93 as previously mentioned permitting movement of the clutch casing 50 with respect to the body 10 so as to adjust the tension of the spring 80 and to adjust the torque applied by the socket joint.
Figures 2, 3 and 4 show how the socket joint of this invention is fitted to a torque wrench. A plug of a torque wrench 100 is inserted in the rectangular socket 18. The rectangular plug 60 then engages with a socket of an article requiring torque. When the controlling ring 30 is rotated to the indicating means 34 to bring the "OFF" indicating means 34 adjacent the arrow on the body 10 the balls 17 which are held in engagement in the flutes 53 by the inner wall of the ring 30 will engage in the grooves 36 of the controlling ring 30. This allows the balls to rise out of the flutes 53 (Fig. 2) and allows rotation of the body 10 relative to the casing 50.
Rotating the body 10 relative to the casing 50 screws the bolt 20 into or out of the positioning nut 90 thus drawing the casing 50 into or out of the body 10 and adjusting the force of the spring 80 acting on the clutch member 702. Torque is indicated by the lines and symbols 55 and 19 engraved on the clutch casing 50 and body 10. When the body 10 is rotated to the required torque position the controlling ring 30 is then rotated to bring the "ON" indicating means 34 adjacent the arrow on the body 10 to force the balls 17 into the guiding flutes 53 and hold them in position to prevent relative rotation of the body 10 and casing 50 (as shown in Figure 2). The force of the spring 80 is such that while the set torque is not exceeded the clutch members will be held in engagement. Once the torque is exceeded the teeth on the members 701, 702 will ride over one another.
It is to be noted that the pre-decided amount of the torque may be changed if need be.
The socket joint of this invention is also applicable to a non-ratchet type torque wrench handle 200 as shown in Figure 5.
While the described embodiments represent the preferred form of the present invention, it is to be understood that modifications will occur to those skilled in this art without departing from the scope of the invention as defined in the appended claims.

Claims

1. A torque limiting device for a socket wrench (100) comprising a torque limiting clutch (70) for transmitting torque from the socket wrench to a socket, the clutch comprising two frictionally engaged clutch members (701, 702); resilient means (80) applying force to one of the clutch members (71) to maintain said clutch members in engagement with one another said force being adjustable; control means (30) movable between a first position wherein said force is fixed and a second position enabling adjustment of said force; a substantially tubular housing (50) telescopically engaged in a substantially tubular portion (15) of a body (10) and containing said torque limiting clutch (70) for transmitting torque from the socket wrench to a socket, one of the clutch members (701) being adapted (60) for engagement in the socket and the other (702) being coupled to said body (10) by way of said resilient means (80), whereby rotation of said housing (50) relative to said body (10) adjusts said force applied by said means (80) characterised in that said body (10) is connectible at its end remote from said housing to said socket wrench and said control means (30) comprises a controlling ring coaxially surrounding said body (10) and rotatable relative thereto between said first and second positions, at least one torque transmitting ball element (17) movably disposed in a through hole (16) in the wall of said body tubular portion (15) and having a dimension greater than the thickness of said wall so as to project from said through hole; and wherein the housing (50) has a plurality of recesses (53) formed in its radially outer surface for partially receiving said torque transmitting ball element when said controlling ring is in said first position to prevent relative rotation of said housing and said body and said controlling ring (30) has at least one recess (36) formed in its radially inner surface for partially receiving said torque transmitting ball element when said controlling ring is in said second position to enable relative rotation of said housing and said body; and wherein said body tubular portion has an axial screw-threaded member (20) along which said housing is screwable by relative rotation of said body and said housing and said resilient means is a compression coil spring coupling said other clutch member to said screw-threaded member.

2. A device as claimed in claim 1 wherein said recesses (53, 36) are axially extending.

3. A device as claimed in claim 1 or 2 wherein the rim of the said recess (36) in said controlling ring (30) is ramp like.

4. A device as claimed in any of claims 1 to 3 wherein said housing (50) is engraved on its outer surface with a length of indicating symbols shorter than the length of each said recess (53) formed in the said surface.

5. A device as claimed in claim 4 wherein said body (10) is provided on its outer periphery with a plurality of indicating symbols (19) cooperating with said indicating symbols engraved on the outer surface of said housing (50).

6. A device as claimed in any of claims 1 to 5 wherein the controlling ring (30) is provided with indicating means (34) on its outer surface.

7. A device as claimed in any of claims 1 to 6 wherein the face of one of said clutch members (701) is provided with a plurality of protrusions (711) and the face of the other of said clutch members (702) is provided with a plurality of corresponding recesses (712).

8. A device as claimed in any of claims 1 to 7 wherein the opposing faces of the two clutch members (701, 702) are formed with interengaging teeth (71).

9. A device as claimed in any of claims 1 to 8 wherein one clutch member (701) of said clutch (70) is integral with a rectangular plug (60) for engagement with the socket.

10. A device as claimed in any of claims 1 to 9 wherein a ring (40) is secured to the body tubular portion (15) and engages in an annular recess (32) in the controlling ring (30); and a pin (33) in one of said annular recess (32) and said ring (40) engages in an arcuate groove (42) in the other of said annular recess (32) and ring (40) to limit rotation of the controlling ring (30) relative to the body (10).

11. A device as claimed in claim 10 wherein said pin (33) is mounted in said annular recess (32) and engages in the arcuate groove (42) in the ring (40).