Information
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Patent Grant
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6796190
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Patent Number
6,796,190
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Date Filed
Wednesday, February 19, 200321 years ago
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Date Issued
Tuesday, September 28, 200419 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
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CPC
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US Classifications
Field of Search
US
- 073 862191
- 073 86221
- 073 86222
- 073 86225
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International Classifications
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Abstract
An electronic torque wrench has a lever arm pivotally coupled to a head member which is adapted for coupling to an associated fastener for rotation therewith about the rotational axis thereof, a torque sensing device being disposed on the head member for movement therewith relative to the lever arm. Different embodiments are provided for different degrees of relative angular movement between the head member and the lever arm.
Description
BACKGROUND
This application relates to torque applying and measuring apparatus and, in particular, to electronic torque wrenches. The application relates specifically to indexable torque wrenches.
Typically, torque wrenches, such as electronic torque wrenches, provide an elongated lever arm with a coupling mechanism, such as a drive lug, on a coupling head fixed at an end of the lever arm and disposed for coupling to an associated socket tool, fastener or other device to be torqued. In a typical arrangement, the coupling device includes a drive lug projecting from the lever arm substantially perpendicular thereto. U.S. Pat. No. 4,643,030 discloses such an arrangement, wherein the torque sensing means comprises a strain gauge assembly disposed on the coupling head and connected by suitable electrical connections to display apparatus carried by the lever arm. In many cases, in using such a fixed-head wrench, a universal joint or the like is required between the head and the fastener in order to reach the fastener. This decreases the accuracy of the measurement.
It is also known to provide indexable torque wrenches, wherein the coupling head is indexable or pivotally movable relative to the lever arm to facilitate access to fasteners in certain applications, such a wrench being disclosed, for example, in U.S. Pat. No. 4,958,541. In such wrenches the torque sensing means, such as a strain gauge assembly, is located on the lever arm.
SUMMARY
This application discloses improved torque wrenching techniques which avoid disadvantages of prior techniques while affording additional structural and operating advantages.
An aspect of the disclosed technique is the provision of an indexable-head torque wrench which affords accurate torque measurement.
In connection with the foregoing aspect another aspect is provision of an indexable-head torque wrench wherein the accuracy of the torque measurement is enhanced.
BRIEF DESCRIPTION OF THE DRAWINGS
For the purpose of facilitating an understanding of the subject matter sought to be protected, there are illustrated in the accompanying drawings embodiments thereof, from an inspection of which, when considered in connection with the following description, the subject matter sought to be protected, its construction and operation, and many of its advantages should be readily understood and appreciated.
FIG. 1
is a top plan view of a first embodiment of torque wrench;
FIG. 2
is a side elevational view of the torque wrench of
FIG. 1
;
FIG. 3
is an enlarged, fragmentary, perspective view of the torque wrench of
FIG. 1
with a protective boot added;
FIG. 4
is a fragmentary, perspective view of the underside of the working end of the torque wrench of
FIG. 2
, with a protective sleeve removed;
FIG. 5
is a view similar to
FIG. 3
of an alternative torque wrench embodiment, with the protective boot removed;
FIG. 6
is a perspective view of the yoke of the torque wrench of
FIG. 5
; and
FIG. 7
is a reduced, fragmentary, side elevational view of the torque wrench of
FIG. 5
, illustrating different positions of the head.
DETAILED DESCRIPTION
Referring to
FIGS. 1-4
, there is illustrated an electronic torque wrench, generally designated by the numeral
10
, having an elongated lever arm
11
with a working end
12
and a handle end
13
. The lever arm
11
includes an elongated, substantially tubular shaft
14
and a housing
15
mounted on the shaft
14
and enclosing approximately the rear two-thirds thereof. The housing
15
may be of generally two-part construction and may be provided with a handle grip
16
. Mounted in the housing
15
may be a user interface
17
, including a suitable display
18
, which may be a digital electronic display, and a control keypad
19
. The lever arm
11
, the housing
15
and the circuitry and structure disposed within the housing
15
may be substantially the same as that disclosed in the copending U.S. application Ser. No. 10/293,006, filed Nov. 13, 2002, and entitled “Electronic Torque Wrench,” the disclosure of which is incorporated herein by reference.
Mounted to the working end
12
of the shaft
14
is a yoke, generally designated by the numeral
20
, which has an elongated, substantially cylindrical body
21
(
FIG. 3
) telescopically received within the working end of the tubular shaft
14
, and fixedly secured in place therein, as by screws
22
(FIG.
2
). The body
21
may be provided with a circumferential flange against which is seated an O-ring
21
a
for sealing against the end of the shaft
14
. Formed diametrically through the body
21
forwardly of the O-ring
21
a
is a slot
23
, which is generally rectangular in transverse cross-section and has an axis substantially perpendicular to the plane of the display
18
. Formed diametrically through the body
21
along an axis substantially perpendicular to that of the slot
23
and intersecting the slot
23
is a bore
24
(FIG.
3
).
Mounted on the body
21
is an elongated head
25
, which has a substantially cylindrical shank
26
provided at one end thereof with a reduced coupling end
27
, which has flattened opposite sides so that it fits upwardly through the slot
23
with a predetermined clearance at the forward and rearward ends thereof. Shank
26
is provided at the opposite end thereof with a drive square
28
, which may be provided with a suitable spring-loaded detent ball in a known manner. The coupling end
27
is pivotally coupled in the slot
23
by a pivot pin
29
extending through the bore
24
and through a complementary bore (not shown) in the coupling end
27
. The end clearance between the coupling end
27
and the slot
23
permits a slight pivotal movement of the head
25
about the axis of the pivot pin
29
, the total pivotal travel of the head
25
being less than forty-five degrees, the head
25
being illustrated in the drawings substantially at the midpoint of its pivotal range.
Referring in particular to
FIG. 4
, there is mounted on the rear side of the head shank
26
a strain gauge assembly
30
, which may be of the type disclosed in the aforementioned copending application Ser. No. 10/293,006. The assembly
30
includes four gauges arranged in a bridge network, including two deflection sensing gauges
31
and
32
and Poisson correction and temperature compensation gauges
33
and
34
. The terminal strips of the gauge assembly are connected via ribbon wires
35
to electronics in housing
15
, the wires
35
extending upwardly into the lower end of the slot
23
and then rearwardly, longitudinally of the body
21
, along a suitable channel (not shown). A cylindrical sheath or sleeve
36
may be provided in surrounding relationship with the shank
26
, covering the strain gauge assembly
30
and protecting it in use, the sheath
36
being formed of any suitable material, such as a suitable elastomeric material. A flexible and resilient boot
38
may be provided for enclosing the working end
12
of the shaft
14
, the O-ring
21
a
and the portion of the body
21
projecting from the shaft
14
, as well as the head
25
down to the drive square
28
. The boot
38
(
FIG. 3
) may be of unitary, one-piece construction and may be formed of a suitable rubber or elastomeric material and will protect the yoke
20
, and particularly the pivot assembly thereof, from dust, dirt and the like, as well as protecting the yoke from potentially damaging contact with surrounding surfaces in use.
As was indicated above, the slot
23
is dimensioned to accommodate a slight pivoting forward and rearward movement of the head
25
to facilitate access to fasteners in certain applications. However, because the strain gauge assembly
30
is mounted on the head
25
, it is always aligned in use with the rotational axis of the fastener being torqued, so that the relative angular position of the head
25
relative to the lever arm
11
has no effect on the value of the torque sensed by the strain gauge assembly
30
.
Referring to
FIGS. 5-7
, there is illustrated another embodiment of electronic torque wrench, generally designated
10
A, which is substantially the same as the torque wrench
10
, described above, except that, in place of the yoke
20
, there is provided a yoke
40
, having an elongated cylindrical body
41
telescopically received in the working end of the shaft
14
and secured in place by any suitable means. The yoke
40
differs from the yoke
20
, described above, fundamentally in that its forward portion is in the form of a clevis
22
, having legs
42
A which cooperate to define therebetween a slot
43
. Diametrically aligned bores
44
extend through the arms
42
a
. The yoke
40
is provided with a head
45
having a shank
46
, integral at one end thereof with a coupling end
47
with flattened sides which extends into the slot
43
of the clevis
42
. The shank
46
is integral at its opposite end with a drive square
48
. A pivot pin
49
extends through the bores
44
and through a complementary bore (not shown) in the coupling end
47
for pivotally connecting the head
45
to the clevis
42
. Because of the clevis nature of this coupling, it will be appreciated that the head
45
is capable of a pivotal movement through at least 180 degrees, as illustrated in FIG.
7
.
The strain gauge assembly
30
may be mounted on the shank
46
of the head
45
, preferably being mounted on a side thereof The strain gauge assembly and the shank
46
may be enclosed within a suitable sheath
50
, having a sleeve portion
51
which encompasses the adjacent end of a suitable cable
52
providing electrical connection to the strain gauge assembly
30
and extending through a suitable hole
53
in the yoke
40
for connecting to the electronics in the housing
15
, in a known manner. The side mounting of the strain gauge assembly
30
on the head
45
accommodates the full range of pivotal movement of the head
45
without having to provide an unduly large slack portion of the cable
52
. It will be appreciated that, if desired, a suitable boot, like the boot
28
described above, could be provided for protecting the yoke
40
. Again, it will be appreciated that, because the strain gauge assembly is mounted on the head
45
, it remains in alignment with the rotational axis of the fastener being torqued, the sensed value of torque being substantially unaffected by the pivotal orientation of the head
45
.
From the foregoing, it can be seen that there has been provided an improved electronic torque wrench with an indexable head, which provides sensed torque values which are unaffected by the orientation of the head relative to the lever arm of the wrench.
The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation. While particular embodiments have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made without departing from the broader aspects of applicants' contribution. The actual scope of the protection sought is intended to be defined in the following claims when viewed in their proper perspective based on the prior art.
Claims
- 1. A torque wrench comprising:a lever arm having a handle end and a working end, a head member coupled to the working end of the lever arm and having an end portion disposed beyond the working end for pivotal movement relative to the lever arm among different working positions, and a torque sensing device carried by the end portion of the head member for movement therewith.
- 2. The torque wrench of claim 1, and further comprising, a coupling apparatus for coupling the head member to the lever arm for limited relative pivotal movement through an angle substantially less than ninety degrees.
- 3. The torque wrench of claim 1, and further comprising, a coupling apparatus for coupling the head member to the lever arm for relative pivotal movement through an angle substantially greater than ninety degrees.
- 4. The torque wrench of claim 3, wherein the coupling apparatus includes a clevis on the lever arm and a coupling portion on the head member straddled by the clevis and pivotally coupled thereto.
- 5. The torque wrench of claim 1, wherein the torque sensing device includes a strain gauge assembly.
- 6. The torque wrench of claim 5, wherein the end portion of the head member includes a shank and a drive lug, the torque sensing device being disposed on the shank.
- 7. The torque wrench of claim 6, and further comprising a sheath encompassing the shank and the torque sensing device thereon.
- 8. The torque wrench of claim 1, wherein the working end of the lever arm has a cavity therein, and further comprising coupling apparatus including a yoke receivable in the cavity and pivotally coupled to the head member.
- 9. A torque wrench comprising:a lever arm having a handle end and a working end, a display device carried by the lever arm intermediate the ends, a head member coupled to the working end of the lever arm and having an end portion disposed beyond the working end for pivotal movement relative to the lever arm among different working positions, a torque sensing device carried by the end portion of the head member for movement therewith, and an electrical connection between the torque sensing device and the display device.
- 10. The torque wrench of claim 9, wherein the display device includes a digital electronic display.
- 11. The torque wrench of claim 9, and further comprising a control keypad carried by the lever arm for controlling operation of the display device.
- 12. The torque wrench of claim 9, and further comprising a coupling apparatus for coupling the head member to the lever arm for limited relative pivotal movement through an angle of less than ninety degrees.
- 13. The torque wrench of claim 9, and further comprising a coupling apparatus for coupling the head member to the lever arm for relative pivotal movement through an angle substantially greater than ninety degrees.
- 14. The torque wrench of claim 9, wherein the electrical connection includes electrical conductors extending inside the lever arm.
- 15. The torque wrench of claim 9, wherein the torque sensing device includes a strain gauge assembly.
- 16. A method for applying torque to a workpiece having a first axis of rotation, the method comprising:providing a head member adapted to be coupled to the workpiece for rotation therewith about the first axis, providing a torque sensing means on the head member for movement therewith, and coupling to the head member a torque-applying lever arm so that the lever arm is moveable relative to the head member about a second axis inclined at a non-zero angle with respect to the first axis among a plurality of positions, whereby the relative angular inclination of the axes does not adversely affect the accuracy of the torque sensing.
- 17. The method of claim 16, and further comprising displaying the torque level sensed by the torque sensing means.
- 18. The method of claim 17, wherein the coupling includes providing a coupling structure permitting limited pivotal movement between the head member and the lever arm through an angle substantially less than ninety degrees.
- 19. The method of claim 17, wherein the coupling includes coupling the head member to the lever arm for relative pivotal movement through an angle substantially greater than ninety degrees.
- 20. The method of claim 16, and further comprising encapsulating the sensing means and associated portions of the head member.
- 21. A torque wrench comprising:lever means having a handle end and a working end, head means for rotating a workpiece about a first axis, means coupling the head means to the working end of the lever means for pivotal movement relative to the lever means among different working positions about a second axis inclined at a non-zero angle with respect to the first axis, and torque sensing means carried by the head means for movement therewith.
- 22. A torque wrench comprising:a lever arm having a handle end and a working end, a head member for rotating a workpiece about a first axis, apparatus coupling the head member to the working end of a lever arm for pivotal movement relative to the lever arm among different working positions about a second axis inclined at a non-zero angle with respect to the first axis, and torque-sensing means carried by the head member for movement therewith.
- 23. The torque wrench of claim 22, wherein the angle is substantially 90°.
- 24. The method of claim 16, wherein the angle is substantially 90°.
- 25. The torque wrench of claim 21, wherein the angle is substantially 90°.
US Referenced Citations (23)