Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE OF THE INVENTION
ELECTRONIC TORQUE WRENCH
BACKGROUND OF THE INVENTION
This application relates to wrenching tools, and, in particular, to torque-
measuring and recording wrenches.
Various types of torque wrenches are known. One common type of
mechanical torque wrench is what is known as a "click"-type wrench which
generates an audible sound, such as a °click," when a predetermined
value of
applied torque is reached. Such wrenches are disclosed, for example, in U.S.
patent no. 4,485,703. In this type of wrench, when a predetermined set force
is
transmitted by the wrench to a workpiece, certain parts within the wrench move
rapidly from a normal position to an actuated position in a manner such as to
generate an audible click-like sound and tactile sensation to signal the
operator
that a predetermined set torque has been reached. The predetermined torque is
set by the operator by rotating coaxial, telescoping tubular parts, so that as
one
part is rotated relative to the other it advances axially relative to the
other along
scale indicia, in the nature of a micrometer. Such wrenches have the advantage
that their manner of use is simple and highly intuitive, so that the wrenches
can
easily be used with little or no training. Additionally, with this type of
wrench,
the operator can always see where the scale is set so that he can always
ascertain the predetermined set torque value while the wrench is in use.
Other types of mechanical torque wrenches have gauges with one or more
pivoting dials. One such wrench has two dials, one of which tracks the applied
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torque both up and down, and the other of which tracks the applied torque only
up, so that it registers the peak torque applied.
Various types of electronic torque wrenches are also known which utilize
electronic circuitry for measuring and/or indicating torque values. Such
electronic devices may have the advantage of being more precise or accurate in
setting predetermined torque values and in measuring applied torque. However,
such electronic torque wrenches are typically much less intuitive to use than
the
mechanical torque wrenches described above. Such wrenches typically have a
keypad with multiple keys which are capable of a number of specialized
functions, many of which may rarely, if ever, be used by a particular
operator.
Considerable training is required to master the operation of such wrenches and
the basic operational functions may be very non-intuitive. Also, in order to
simultaneously display both a pre-set torque value and an applied torque
value,
such electronic wrenches must have relatively complex and expensive displays.
While wrenches with more simplified and inexpensive displays are known, they
typically register a display of the preset torque while it is being set, but
then,
after the setting function is accomplished, the display returns to zero in
preparation for recording the applied torque during use of the wrench. If the
operator puts the wrench down after setting the predetermined torque and
returns to it later for use, he will have to typically perform some keypad
function
in order to view the preset torque. Also, such electronic wrenches lack the
familiar audible/tactile indication when the predetermined set torque value is
reached, and may provide some other type of visible and/or audible indication,
or even require that the user watch a display.
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SUMMARY OP THE INVENTION
There is described in this application an improved electronic torque
wrench which is more intuitive to use than the previous electronic wrenches,
simulating basic features of mechanical torque wrenches while maintaining
advantages of prior electronic torque wrenches.
An embodiment of an electronic torque wrench includes a workpiece-
engaging head carried by a housing which also carries torque measuring
apparatus including a processor operating under stored program control. A user
interface is coupled to the torque measuring apparatus and includes a data
input
device and annunciator apparatus. The processor program responds to the input
device for selectively setting or changing a preset torque level at any time,
and
compares torque values measured by the torque measuring apparatus with the
preset torque level for causing the annunciator apparatus to produce an
indication when the measured torque value coincides with the preset torque
level.
An embodiment also includes an electronic torque wrench, wherein the
user interface includes a keypad having an on/zero key for powering up the
wrench and setting a zero level, a units key for toggling among plural
different
units of torque measurement, an increment key for incrementing a preset torque
level and a decrement key for decrementing a preset torque level.
A torque wrench embodiment also includes a housing assembly including
telescoping tubular inner and outer housing portions with registered apertures
therein and a bezel assembly disposable in the outer housing portion aperture
and carrying torque measuring apparatus, the housing portions and the bezel
assembly all being interconnected by a single fastener.
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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 an embodiment of an electronic torque wrench
having a four-key keypad;
FIG. 2 is a front elevational view of the torque wrench of FIG. 1;
FIG. 3 is a slightly reduced, exploded, perspective view of the torque
wrench of FIG. 1;
FIG. 4 is an exploded view of the handle assembly of the wrench of FIG.
1;
FIG. 5 is an enlarged, exploded, perspective view of the battery tray of
the torque wrench of FIG. 3;
FIG. 6 is an enlarged, exploded, perspective view of the end cap assembly
of the torque wrench of FIG. 3;
FIG. 7 is an enlarged, top-plan view of the sensory yoke and strain gauge
of the torque wrench of FIG. 3;
FIG. 8 is a front elevational view of the sensory yoke and strain gauge of
FIG. 7;
FIG. 9 is sectional view taken generally along the line 9-9 in FIG. 7;
FIG. 10 is an enlarged, exploded, perspective view of the bezel assembly
of the torque wrench of FIGS. 2 and 3;
FIG. 11 is a top plan view of the bezel of FIG. 10;
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FIG. 12 is a sectional view taken generally along the line 12-12 in FIG. li;
FIG. 13 is a bottom plan view of the bezel of FIG. li;
FIG. 14 is a view similar to FIG. 11 of a modified bezel;
FIG. 15 is a functional block diagram of the electronic circuitry of the
torque wrench of FIGS. 1 and 2; and
FIG. 16 is a flow chart diagram of the software for operating the circuitry
of FIG. 15.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1-3, there is illustrated an electronic torque wrench,
generally designated by the numeral 10, having a housing 15 including an inner
housing portion in the form of an elongated cylindrical body tube 11 with a
large,
elongated, rectangular aperture 12 in the upper portion thereof intermediate
its
ends and a rectangular notch 13 formed in the upper rear edge thereof. A
circular hole 14 is formed in the bottom portion adjacent to the forward end
of
the notch 12. Referring also to FIGS. 7-9, a sensor yoke 20 has a cylindrical
base 21 which is fitted in the forward end of the body tube 11, the base 21
having an axial bore 22 formed in the rear end thereof and a rectangular
groove
or channel 23 formed in the outer surface thereof and extending longitudinally
from the rear end of the base 21 to about midway along its length. The forward
half of the base 21 defines a reduced-diameter neck portion 24 having parallel
flats 25 formed on opposite sides thereof, one of which defines a recess
communicating with the channel 23. Projecting forwardly from the front end of
the base 21 are a pair of spaced clevis legs 26; respectively having aligned
pivot
holes 27 therethrough. The base 21 has two internally threaded bores 28
formed radially therein for respectively receiving fasteners 29 (see FIG. 3)
to
secure the yoke 20 in place in the body tube 11.
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A ratchet head 30 is coupled to the sensor yoke 20. The ratchet
mechanism of the head 30 may be of the type disclosed in U.S. patent no.
6,125,722. The head 30 has a neck 31 projecting rearwardly therefrom which is
received between the clevis legs 26 of the yoke 20, the neck 31 having a bore
32 therethrough which aligns with the pivot holes 27 for receiving a pivot
screw
33 to allow pivotal movement of the head 30 relative to the yoke 20, as
indicated in phantom in FIG. 2. While a pivoting or indexible head 30 is
illustrated, it will be appreciated that other types of ratcheting or non-
ratcheting,
pivoting or non-pivoting, fixed or removable heads could be mounted on the
forward end of the body tube 11, with suitable modifications to the sensor
yoke
20.
Referring also to FIG. 4, the housing 15 includes an outer housing portion
in the form of a generally tubular handle assembly 40, which is of
fundamentally
two-part construction, including a lower housing assembly 41 and an upper
housing 50, which are mateably joined and secured together, as by ultrasonic
welding. The lower housing assembly 41 has a generally part-cylindrical body
42 with a reduced-diameter neck portion 43 at the forward end thereof provided
with a circumferentially extending rectangular slot 44. A circular hole 45 is
formed through the body 42 adjacent to the neck portion 43 and is surrounded
at the inner surface of the body 42 by a bushing 46. A foot 47 projects
downwardly from the body 42 intermediate its ends. The rear half of the body
42 is provided with upstanding, arcuate grip flanges 48. Projecting rearwardly
from the body 42 is a reduced-diameter, externally threaded part-cylindrical
neck portion 49.
The upper housing 50 has a generally part-cylindrical body 52 having a
reduced-diameter neck portion 53 projecting from its forward end with a
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rectangular, circumferentially extending slot 54 therein. A large, elongated,
generally rectangular aperture 55 is formed in the forward half of 'the body
52.
The lower edges of the body 52 are provided with large cutouts 56 in the rear
half thereof for respectively accommodating the grip flanges 48. An externally
threaded, reduced-diameter part-cylindrical neck portion 59 projects
rearwardly
from the body 52.
In assembly, the lower housing assembly 4I and the upper housing 50
are joined along their longitudinal edges, such as by ultrasonic welding, with
the
grip flanges 48 respectively received in the cutouts 56, the neck portions 43
and
53 cooperating to form a forward neck and the neck portions 49 and 59
cooperating to form a rearward neck. A trim ring 58 (FIG. 3) is fitted over
the
forward neck and has tabs (not shown) which respectively snap fit into the
slots
44 and 54 to retain the trim ring 58 in place. The rear portion of the body
42,
including the grip flanges 48, may be over molded with a grip 57 (FIGS. 3 and
4)
formed of a suitable elastomeric material, such as that sold under the trade
name SANTOPRENE.
Referring also to FIG. 5, the torque wrench 10 is provided with a battery
support or tray assembly 60, which is of fundamentally two-part construction,
including a lower tray 61 and an upper tray 70. The lower tray 61 has an
elongated, part-cylindrical base 62, provided along approximately the rearward
two-thirds thereof with upstanding sides 63, respectively provided at their
upper
edges with laterally outwardly extending flanges 64, each having a plurality
of
longitudinally spaced rectangular notches 65 in the outer edge thereof. The
sides 63 are joined at their forward ends by an upstanding partition 66,
integral
with the base 62. An arcuate, radially extending end flange 67 projects from
the
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base 62 and sides 63 at their rearward ends. Projecting upwardly from the base
62 at its forward end is a cylindrical bushing 68.
The upper tray 70 has a part-cylindrical base 72 with a length
substantially equal to the distance between the partition 66 and the end
flange
67 of the lower tray 61. Formed in the forward end of the base 72 is an
elongated rectangular notch 73. Integral with the base 72 along its opposite
side edges are laterally outwardly extending flanges 74, respectively provided
with depending, longitudinally spaced-apart posts or stakes 75. Projecting
upwardly from one of the flanges 74 are a plurality of longitudinally-spaced,
short lugs 75a. In assembly, the upper tray 70 is fitted over the lower tray
61,
with the flanges 74 respectively abutting the flanges 64 and the posts 75
respectively snap-fitted into the notches 65 (see FIG. 3) to form a generally
cylindrical compartment closed at the forward end by the partition 66 and open
at the rearward end. A helical compression spring 76 is seated at the forward
end of the compartment against the partition 66 and may rearwardly urge a
suitable contact plate 69. An elongated contact strip 78 lies along the outer
surface of the one flange 75 and has a notch 78a for receiving a lug 75a to
position the strip. The rear end of the contact strip 78 is bent to make
contact
with a rear contact plate 79, which is biased forwardly by a helical
compression
spring 79a (see FIG. 3). The battery tray assembly 60 is dimensioned to
receive
three series-stacked, standard '~AA" alkaline cells, with a positive terminal
contacting the contact plate 69 and a negative terminal contacting the contact
plate 79. A tab on the contact plate 69 and the forward end of the contact
strip
78 will, respectively, be connected by suitable soldered ribbon wires 71 to
the
remainder of the circuitry, to be described more fully below.
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Referring to FIG. 3, in assembly of the housing 15, the rear end of the
body tube 11 is telescopically received in the forward end of the handle
assembly 40 until the aperture 12 lies immediately beneath the aperture 55,
substantially in registry therewith. The forward end of the battery tray
assembly
60 is then telescopically received in the rear end of the handle assembly 40
and
into the rear end of the body tube 11 until the bushing 68 is in registry with
the
hole 14 in the body tube 11. The notch 13 in the body tube 11 will then be in
registry with a motor holder receptacle ( not shown) formed at the rear end
inside the upper housing 50.
Referring now also to FIGS. 10-13, the housing 15 includes a bezel
assembly 80, the parts of which are illustrated in FIG. 10. The bezel assembly
80 includes a generally rectangular printed circuit board (~~PCB") assembly
82.
Mounted on the PCB assembly 82 is a buzzer 83, provided with a seal 84. A
keypad plate 86 overlies the PCB assembly 82 and includes four keys. Formed
in the keypad plate 86 is a longitudinally extending, narrow rectangular notch
87. An elongated, thin, elastomeric connector 88 is received in the notch 87
and
provides connection between terminals on the PCB assembly 82 and terminals
on an LCD display 89, which is provided with a lens 90.
The bezel assembly 80 also includes a generally part-cylindrical bezel 91,
which is dimensioned to mateably fit in and close the aperture 55 in the
handle
assembly 40 (see FIG. 3). The bezel 91 has a generally rectangular aperture 92
therein dimensioned to receive the upper portion of the lens 90. Formed
through the bezel 91 adjacent to the forward end thereof are a plurality of
small
apertures 93 for the buzzer 83. Formed in the upper surface of the bezel 91 at
the rear end thereof is a generally rectangular recess 94, in the bottom wall
of
which are formed four keyholes 95, respectively positioned and shaped to
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receive the keys of the keypad plate 86. Depending from the front end of the
bezel 91 is a cylindrical bushing 96, which receives an internally threaded
insert
97. A generally rectangular tab 98 depends from and projects rearwardly from
the rear end of the bezel 91.
In assembly, the PCB assembly 82 is fixedly secured to the bezel 91 by
suitable means, such as screws 99, with the remaining parts of the bezel
assembly 80 illustrated in FIG. 10 sandwiched therebetween. The elastomeric
connector 88, which is a type of connector normally used to accommodate
considerable flexing between connected parts is, in this case, very thin so as
to
provide a low-profile and rigidly-assembled bezel assembly 80 with minimal
relative movement of internal parts.
The keypad plate 86 illustrated in FIG. 10 is provided with four keys, the
functions of which will be described below. In a modified form of the torque
wrench 10, additional keys may be provided, in which case a modified keypad
plate would be used and the bezel 91 would be modified to provide an
appropriate number of (e.g., six) keyholes. Such a modified bezel assembly is
illustrated in FIG. 14 and is designated 80A and is substantially identical to
the
bezel assembly 80, except for the number of keys and the fact that an output
jack and output jack cover and associated port (not shown) may be provided.
The assembled bezel assembly 80 or 80A is fitted into the aperture 55 in
the handle assembly 40, with the tab 98 slipped beneath the wall of the upper
housing 50 at the rear end of the aperture 55. When thus installed, the
bushing
96 and threaded insert 97 will register with the bushing 68 of the battery
tray
assembly 60 and the hole 14 in the body tube 11 (see FIG. 3), so that a single
screw 100 may be received through the hole 14 and the bushing 68 and
threaded into the insert 97 to hold the entire assembly together.
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Referring to FIGS. 3 and 6, the rear end of the housing 15 is closed by an
end cap assembly 101, which includes a generally cup-shaped end cap 102 and
a threaded insert 103 adapted for threaded engagement with the threaded neck
portions 49, 59 of the handle assembly 40. The contact plate 79 and spring 79a
may be seated in the end cap 102 against an end surface of a post 106, the
spring receiving a centering lug 107 projecting from the end of the post 106.
Thus, when the end cap assembly 101 is mounted in place, the spring 79a
resiliently urging the contact plate 79 against the rear end of the strip 78.
If
desired, an alternative form of end cap assembly (not shown) could be provided
with a transverse hanging hole formed therethrough.
Referring to FIG. 10, the four keys of the keypad plate 86 include an
"on/zero" key 111, a "units" key 112 for toggling among different torque-
measurement units, an "increment" key 113 and a "decrement" key 114. A
storage key 115 and a download key 116 could also be provided in a six-key
bezel assembly 80A (see FIG. 14). To further distinguish the keys, the key 111
is circular in shape; the key 112 is "U"-shaped, and the keys 113 and 114 are
triangular to simulate arrows. The storage and download keys 115, 116 if
provided, may be square.
The wrench 10 includes a strain gauge assembly 120. Referring to FIGS.
7 and 8, the strain gauge assembly 120 includes 4 gauges arranged in a bridge
network, including two deflection sensing gauges 121 and 122 and Poisson
correction and temperature compensation gauges 123 and 124. The strain
gauge assembly 120 is physically mounted on one of the flats 25 of the sensor
yoke 20, the terminal strips thereof being connected to the PCB assembly 82 by
ribbon wires 119 which extend through the channel 23 in the sensor yoke 20.
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The wrench 10 also includes a vibratory motor M, which is physically
accommodated in a receptacle formed at the rear end inside the upper housing
50 (not shown) and in the notch 13 of the body tube 11, and is connected by
wires to the PCB assembly 82.
Referring to FIG. 15, there is illustrated a functional block diagram of an
electronic circuit 110 for controlling the operation of the torque wrench 10.
The
circuit 110 includes a processor 125, which may be in the nature of a suitable
microcontroller, such as an NEC model 789456, which may have a crystal-
controlled clock speed of 4.915 MHz. The processor 125 operates under control
of a program, which may be stored within the processor. An EEPROM 126 may
be provided to store setup, preset and calibration parameters. The output of
the
strain gauge bridge 120 is applied to the processor 125 through an analog-to-
digital converter (ADC) 127, which may be an Analog Devices model AD7705BR.
The keypad plate 86 constitutes a data input device which is coupled to the
processor 125 and forms part of a user interface, which also includes
annunciator apparatus, which may include a buzzer 128, the vibratory motor M
and the LCD display 89, all coupled to the processor 125. The battery support
assembly 60 carries a battery pack 129, which includes the three ~~AA"
alkaline
cells to power the wrench 10. The battery pack 129 is coupled to a voltage
regulator 130, which produces a V++ voltage, which may, for example, be 3.3
volts, and which is applied to the EEPROM 126, the processor 125, the keypad
86 and the buzzer 128. The battery pack 129 is also coupled to a voltage
regulator 131, which produces a V+ supply voltage which may, for example, be
3.0 volts, and which is applied to the strain gauge bridge 120 and the ADC
127,
the regulator 131 being enabled under the control of the processor 125. The
battery pack 129 is also coupled to a motor regulator 132, which produces a
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suitable supply voltage to the vibratory motor M, which may, for example, be
3.0 volts, the motor regulator 132 being enabled under the control of the
processor 125.
The strain gauge bridge 120 mounted on the sensor yoke 20 constitutes a
sensing device in the nature of a bending-beam measurement transducer, the
two deflection sensing gauges 121 and 122 being aligned with the primary
bending plane of the beam, and the second pair of gauges 123 and 124 being
aligned perpendicular to the primary bending plane. The strain gauge bridge
120 is excited by regulated V+ voltage and delivers a differential output,
which
may be approximately 6.5mV at full-scale torque, which output signal is fed
through the ADC 127 to the processor 125. The buzzer 128 may be an
electromagnetic buzzer, which is driven directly by the processor 125 and may
provide audible keypush, preset and overload alerts to the wrench user. The
vibratory motor M may be a DC motor rotating an off-axis weight, of the type
typically used in personal pagers. The motor M is driven momentarily by the
regulated output voltage of the regulator 132 and provides the user with a
tactile preset coincidence alert.
In operation, when the user desires to utilize the torque wrench 10, the
wrench is turned on by pressing the on/zero key 111. The first time that the
wrench is powered up in this manner, the wrench will execute a self test and a
zero set operation under the control of suitable program routines, followed by
causing the display 89 to display flashing "0000", indicating program mode.
The
wrench is capable of operation in different modes and these can be manually
selected by the user by entering a suitable code number using the increment
and decrement keys 113 and 114. Then the units key 112 is pressed to accept
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or enter the code, whereupon the wrench shuts off. The program mode can be
exited by pushing the on/zero key without leaving any changes.
The next time the unit is powered up the display will flash ~~UCAL" for ten
seconds, indicating that the wrench is uncalibrated. The user must then
proceed
with a calibration procedure to establish full-scale range. After the wrench
is
calibrated, subsequent power-ups will take 1.5 seconds, during which the
buzzer
pulses for 0.2 second and the wrench executes self test and zero set routine
followed by displaying "0000" for one second, and then displaying any
previously-entered set point or predetermined torque level or, if none has
been
previously set, displaying 20% of full-scale torque as a default set point.
The user may select the units of torque measurement by scrolling through
the several different available units; utilizing the units key 112. The first
time
the units key is depressed the display 89 will display one of the several
units
selections available. Each push of the units key 112 shifts to the next
measurement unit.
The operator can then select a preset torque level or alter a previously-set
torque level by using the increment and decrement keys 113 and 114, each
push one of these keys incrementing or decrementing the currently-displayed
value by one unit. Increment/decrement speed increases as the increment and
decrement keys 113 and 114 are held down. The total time to traverse from the
center of the measurement scale to either end is less than seven seconds. Once
the predetermined torque level is set, the display 89 will continue to display
that
level until torque is applied by the wrench or until another key is pressed or
an
internal timer times out.
Once the predetermined torque level is set, the user then utilizes the
wrench in a normal manner to apply torque. As soon as torque exceeds the
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minimum specified display range, the display 89 will begin to display the
measured torque value and will track the applied torque, which may be from 5%
of full scale up to 125% of full scale. When torque application is released,
the
display 89 will display the peak torque value applied with a flashing display
for
10 seconds. If, during that 10-second interval, the torque is reapplied the
display 89 will revert to its tracking mode. Pushing any key will cancel the
10-
second peak display period and the display will revert to the function of
whatever key was pressed.
When the applied torque reaches the predetermined torque level minus a
2% tolerance, the processor 125 will enable the motor regulator 132 to power
the vibratory motor M, which will then run continuously until torque is
released.
Also, at this time, the buzzer 128 will sound an audible alert for 0.5
seconds. At
and above 100% of full scale, the buzzer pulses at a 5-Hz rate. At 125% of
full
scale the display 89 locks up and displays "----", indicating overload of .the
wrench. Pressing the on/zero key 111 will reinitiate a self test.
The user may, at any time, display the predetermined torque level ,by
pushing the on/zero key 111, which will momentarily show "0000" for one
second and then display the predetermined torque level.
If the sensing apparatus has been damaged due to excessive torque
applied, resulting in tare greater than 20% of full scale, then the display 89
will
show "ErrO." The wrench 10 also will provide a low battery alert. Normally,
the
display will show a filled-in outline of a battery when it is fully charged, a
half-
filled outline when the battery is at about half-capacity and, when there is
approximately 0.5 hours of battery life remaining, the LCD display 89 will
display
a flashing battery outline symbol. When this display is active, the accuracy
of
the wrench will not be affected by a vibratory motor loading. When the
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are depleted, the display 89 will flash "BAtt", whereupon the wrench will not
operate unless the batteries are exchanged.
In calibrating the wrench 10, the user employs the following procedure:
1. Push ON/ZERO KEY to turn wrench on.
2. Momentarily apply full-scale torque three times in the CW direction.
3. Select UNITS (Nm, ft-Ib, or in-Ib)
4. While pushing the ON/ZERO key, push UP key once momentarily
and then push DOWN key until display shows "CAL."
5. With no torque applied, push UNITS key once to set zero into
memory.
6. Apply continuous full-scale CW torque using certified torque source.
7. Use UP and DOWN keys to adjust wrench display to match applied
torque.
8. Push UNITS key to set full scale into memory.
9. Push ON/ZERO key to accept new calibration parameters. Display
momentarily reads "CAL" and then shuts down.
10. Verify calibration at 20%, 60% and 100% of full-scale in both CW
and CCW directions.
If the on/zero key 111 is pushed anytime after step 4 and before step 8,
the wrench will exit the calibration mode and retain the previous calibration
parameters. If the wrench is left idle for two minutes, from any point in the
calibration procedure, it will default to the previous calibration parameters
and
shut down.
If the wrench lies idle for two minutes, i.e., no keys are pushed and no
torque is applied, a timer will time out and the wrench will automatically
turn off.
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The foregoing description applies to a wrench configuration which is
designed for automotive service technicians and the like. An alternate
configuration might be utilized for industrial uses, such as in automobile
assembly plants and the like. That configuration is similar, except that the
wrench may also have user-adjustable tolerance values.
Referring to FIG. 16, there is illustrated a flow chart, illustrating a
software program routine 140 for operating the torque wrench 10. When the
wrench is powered up, at 141, it executes the power up routine described
above,
pulsing the buzzer for 0.2 second, executing the self test or display
diagnostic
function at 142 and the zero set function at 143. Then, at 144, it displays
the
previous set point or predetermined torque level or, if one has not been
previously set, displays 20% of full-scale torque as a default preset. Then,
at
145, the program sets a two-minute timer and checks at 146 to see if the timer
has timed out. If it has, the wrench is turned off at 147.
After setting the timer at 145, the program also checks at 148 to see if a
keystroke has occurred, i.e., that one of the keypad keys has been pushed. If
not, the program then, at 149, measures torque applied by the wrench, as
sensed by the strain gauge bridge 120, and then checks, at 150, to see if the
measured torque is above a minimum value, e.g., 5% of full-scale. If the
measured torque is above the minimum, the routine first, at 151, triggers the
track mode, causing the display 89 to track and display the measured torque,
and then returns to 145 to reset the timer and goes to 152 to stop the ten-
second delay for the peak hold display and returns to 144 to display the set
point. At this point, the program also checks at 153 to see if set point
coincidence has occurred, i.e., whether the measured torque is substantially
equal to the predetermined torque level. If it is, the program, at 154,
triggers
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the preset alarm, causing the vibratory motor M and the buzzer 83 to generate
their alarm signals in the manner described above and then returns to 145 and
152. The program next checks at 155, to see if the measured torque is above
the full scale level. If so, it triggers the full scale alarm at 156, causing
the
buzzer to give its appropriate alarm, as described above, and then returns to
145 and 152. The program next checks at 157 to see if measured torque is
above 125% of full scale. If so, it triggers the overload alarm at 158 and
locks
the display at 159. The program next checks at 160 to see if torque
application
has been released. If so, it triggers the peak hold mode at 161, causing the
display 89 to display the peak torque value, and starts a ten-second delay
period
at 152 to display the peak value for ten seconds, after which it returns to
144 to
resume displaying the set point. If torque release has not occurred at 160,
the
program returns to 149 to continue measuring torque.
If, at 148, a keystroke has occurred, the program checks at 162, 163, 164
and 165, respectively, to see if it is the on/zero key, the units key, the
increment key or the decrement key which has been actuated to activate the
zero/tare function at 166, change the units at 167, increment the set point at
168 or decrement the set point at 169, in each case thereafter resetting the
timer at 145 and stopping the ten-second delay period at 152 and returning to
144 to display the set point.
From the foregoing, it can be seen that there has been provided an
improved electronic torque wrench which is characterized by intuitive
functions
which maintain the advantages of prior electronic torque wrenches while, at
the
same, time effectively simulating prior mechanical "click"-type torque
wrenches.
The matter set forth in the foregoing description and accompanying
drawings is offered by way of illustration only and not as a limitation. While
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CA 02510852 2005-06-27
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.
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