U.S. patent application number 09/910539 was filed with the patent office on 2003-02-06 for impact tool battery pack with acoustically-triggered timed impact shutoff.
Invention is credited to Carney, Steven C., Crass, Matthew M..
Application Number | 20030024716 09/910539 |
Document ID | / |
Family ID | 25428958 |
Filed Date | 2003-02-06 |
United States Patent
Application |
20030024716 |
Kind Code |
A1 |
Carney, Steven C. ; et
al. |
February 6, 2003 |
IMPACT TOOL BATTERY PACK WITH ACOUSTICALLY-TRIGGERED TIMED IMPACT
SHUTOFF
Abstract
An electrically powered impact tool has a removably mountable
battery pack which includes an acoustic detection circuit for
detecting sounds generated by the impact mechanism in use and, in
response to such detection, starts an adjustable time period, at
the end of which a relay is actuated for disconnecting the battery
of the battery pack from the tool motor for a predetermined time
period. This serves as a torque-limiting mechanism where the tool
is a torque-applying tool. The time period is adjustable by a dial
on the battery pack housing and the control circuitry may be
selectively powered through a switch on the battery pack
housing.
Inventors: |
Carney, Steven C.; (Prairie,
WI) ; Crass, Matthew M.; (Prairie, WI) |
Correspondence
Address: |
SEYFARTH SHAW
55 EAST MONROE STREET
SUITE 4200
CHICAGO
IL
60603-5803
US
|
Family ID: |
25428958 |
Appl. No.: |
09/910539 |
Filed: |
July 23, 2001 |
Current U.S.
Class: |
173/217 |
Current CPC
Class: |
B25B 23/1405 20130101;
B25B 23/1475 20130101 |
Class at
Publication: |
173/217 |
International
Class: |
B25D 001/00 |
Claims
We claim:
1. A battery pack for an electrically-powered device, the battery
pack comprising: a housing; a battery disposed within the housing;
a connection circuit for electrically connecting the battery to the
associated device; and a control circuit in the housing connected
to the connection circuit for controlling operation thereof, the
control circuit including a detector for detecting vibrations
generated by the associated device in use and producing a control
signal, and a timer responsive to the control signal for initiating
a predetermined time period, the control circuit being operable for
disconnecting the connection circuit at the expiration of the time
period.
2. The battery pack of claim 1, wherein the housing includes a plug
portion receivable in a socket portion of the associated impact
tool for mounting the battery pack on the tool.
3. The battery pack of claim 1, wherein the control circuit
includes a relay having normally-closed contacts in the connection
circuit.
4. The battery pack of claim 1, and further comprising an ON-OFF
switch for selectively connecting the battery to the control
circuit for powering same.
5. The battery pack of claim 4, and further comprising an indicator
connected to the switch for indicating when the control circuit is
powered.
6. The battery pack of claim 1, wherein the timer includes a
circuit for selectively adjusting the length of a predetermined
time period.
7. The battery pack of claim 1, wherein the timer includes
circuitry for controlling the length of time that the connection
circuit is disconnected at the expiration of the predetermined time
period.
8. The battery pack of claim 1, wherein the detector is an acoustic
detector.
9. The battery pack of claim 1, wherein the acoustic detector
includes circuitry for selectively adjusting the sound level to
which the detector will respond.
10. An electrically powered device comprising: an electric motor;
an operating mechanism driven by the motor; and a battery pack
having a battery and a connector adapted to be removably connected
to the motor for powering same, the battery pack including a
control circuit having a detector for detecting vibrations
generated by the operating mechanism in use to produce a control
signal, and a timer responsive to the control signal for initiating
a predetermined time period, the control circuit being operable for
disconnecting the battery from the connector at the expiration of
the time period.
11. The device of claim 10, and further comprising a housing for
the motor and impact mechanism, and structure for mounting the
battery pack on the housing.
12. The device of claim 11, wherein the structure includes a turret
portion on the battery pack and a socket portion in the housing for
receiving the turret portion.
13. The device of claim 11, and further comprising latch mechanism
for releasably retaining the battery pack on the housing.
14. The device of claim 10, and further comprising an ON-OFF switch
for selectively connecting the battery to the control circuit for
powering same.
15. The device of claim 10, wherein the timer includes a circuit
for selectively adjusting the length of a predetermined time
period.
16. The device of claim 10, wherein the device is an impact tool,
the operating mechanism including an impact mechanism having a
hammer and an anvil.
17. The device of claim 16, wherein the impact tool is a
torque-applying tool.
18. A battery pack for an electrically-powered impact tool, the
battery pack comprising: a housing; a battery disposed within the
housing; means for connecting the battery to the associated tool;
means for detecting vibrations caused by impacts generated by the
associated tool and producing a control signal; timing means
responsive to the control signal for initiating a predetermined
time period; and means for disconnecting the battery from the
associated tool at the expiration of the time period.
19. The battery pack of claim 18, and further comprising means for
selectively connecting the battery to the means for detecting and
to the timing means and to the means for disconnecting.
20. The battery pack of claim 19, and further comprising means for
indicating when the means for detecting and the timing means and
the means for disconnecting are powered.
21. The battery pack of claim 18, wherein the timing means includes
means for selectively adjusting the length of the predetermined
time period.
22. The battery pack of claim 18, wherein the timing means includes
means for determining the length of time that the battery remains
disconnected from the associated tool at the expiration of the
predetermined time period.
23. The battery pack of claim 18, wherein the means for detecting
includes means for selectively adjusting the vibration level to
which the means for detecting will respond.
24. A method for controlling operation of an electrically-powered
impact tool, comprising: providing a battery pack removably
connectable to the tool for powering same, detecting sounds of
impacts generated by the impact tool, beginning a predetermined
time period in response to detection of the impact sounds, and
automatically disconnecting the battery pack from the tool upon
expiration of the time period.
25. The method of claim 24, and further comprising mounting the
battery pack on the impact tool.
26. The method of claim 24, and further comprising selectively
adjusting the length of the predetermined time period.
27. The method of claim 24, and further comprising determining the
length of time that the battery pack remains disconnected from the
tool upon expiration of the predetermined time period.
28. The method of claim 24, and further comprising adjusting the
level of sound which can be detected in the detecting step.
Description
BACKGROUND
[0001] The present invention relates to power tools and, in
particular, to tools of the type powered by a detachable battery
pack. The application relates in particular to impact tools, such
as impact wrenches or other torque-applying impact tools.
[0002] It is known to provide powered torque-applying tools with
means for controlling or limiting the torque applied by the tool to
prevent over-torquing of fasteners or the like. These
torque-limiting techniques typically utilize fairly complex and
expensive mechanical, electromechanical or electronic devices for
measuring applied torque and comparing it to a predetermined
reference torque level. Such techniques are capable of providing
fairly precise torque limiting or control.
[0003] However, it is frequently acceptable or desirable to provide
a fairly rough or coarse torque limiting function in applications
where precise torque control may not be necessary. It is known to
provide impact tools with a built-in acoustic or vibrational
detector, such as a microphone, to detect the sounds of impacts
generated by the tool when torque starts to build up. One such
device is disclosed, for example, in U.S. Pat. No. 5,277,261, which
counts the number of impacts and disconnects power from the motor
after a predetermined number of impacts has been counted. However,
in order to utilize this feature, a person must purchase a tool of
the type which incorporates the feature.
SUMMARY
[0004] This application is directed to electrically-powered devices
and power packs therefor which avoid the disadvantages of prior
devices while affording additional structural and operating
advantages,
[0005] An important aspect is the provision of a technique for
simply and economically providing a pre-existing device with an
acoustically triggered control function.
[0006] In connection with the foregoing aspect, another aspect is
the provision of a combination of an electrically powered device
and a removably connectable battery pack therefor, wherein the
acoustically-triggered control function is incorporated in the
battery pack.
[0007] Another aspect of the invention is the provision of a
battery pack of the type set forth.
[0008] A still further aspect is the provision of a method for
acoustically controlling shutoff of an electrically-powered impact
tool.
[0009] Certain ones of these and other aspects may be attained by
providing a battery pack for an electrically-powered device, the
battery pack comprising: a housing; a battery disposed within the
housing; a connection circuit for electrically connecting the
battery to the associated device; and a control circuit in the
housing connected to the connection circuit for controlling
operation thereof, the control circuit including a detector for
detecting vibrations generated by the associated device in use and
producing a control signal, and a timer responsive to the control
signal for initiating a predetermined time period, the control
circuit being operable for disconnecting the connection circuit at
the expiration of the time period.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] 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.
[0011] FIG. 1 is a side elevational view of an electrically-powered
impact tool having mounted thereon a battery pack incorporating an
acoustically-triggered control circuit;
[0012] FIG. 2 is an enlarged, perspective view of the battery pack
of FIG. 1; and
[0013] FIG. 3 is a schematic electrical circuit diagram of the
circuitry of the battery pack of FIG. 2.
DETAILED DESCRIPTION
[0014] Referring to FIG. 1, there is illustrated an impact tool,
generally designated by the numeral 10, having a pistol-grip
housing 11, including a barrel portion 12 in which are mounted an
electric motor 13 and an impact mechanism 14 including a hammer 15
and an anvil 16, the latter being coupled to an output drive square
17, all in a known manner. The housing 1 1 includes a handle 18 on
which is mounted a trigger 19 for controlling operation of the
motor 13. A suitable tool, such as a socket or the like, may be
mounted on the drive square 17 for interfacing with an associated
fastener or the like to which torque is to be applied, again all in
a known manner. The impact tool 10 is of a general type offered by
a number of manufacturers, the construction and operation of which
are well understood by those skilled in the art and, therefore,
will not be further described herein.
[0015] The impact tool 10 is powered by a battery pack 20, which is
detachably mountable on the handle 18 of the tool 10. Referring
also to FIG. 2, the battery pack 20 has a housing 21 which includes
an enlarged base 22 on which are mounted a pair of latch mechanisms
23 (one shown) adapted for cooperation with keeper structure (not
shown) on the handle 18, in a known manner. Also mounted on the
base 22 is an ON-OFF switch 24 and a control dial 25, the purposes
of which will be explained more fully below. Projecting upwardly
from the base 22 is a turret 26 which is dimensioned to be received
in the hollow lower end of the handle 18 of the tool 10, and is
provided with electrical terminals 28 for interface with mating
terminals (not shown) in the handle 18 for electrically connecting
the battery pack 20 to the motor 13 through the trigger mechanism
19. It will be appreciated that when the battery pack 20 is mounted
in place on the handle 18, as illustrated in FIG. 1, the latch
mechanisms 23 engage to retain the battery pack in place, the latch
mechanisms 23 being manually operable for releasing the battery
pack 20 to remove it.
[0016] Referring now to FIG. 3, there is disclosed in the battery
pack housing 21 a battery 30 and a control circuit. The battery 30
may be of the type suitable for operating the impact tool 10, such
as a 12-volt Ni-Cad battery, although it will be appreciated that
other battery types and battery voltages could be used, depending
upon the particular tool being powered. The positive and negative
terminals of the battery 30 are respectively connected to the
terminals 28 on the turret 26, the positive battery terminal being
connected to its associated terminal 28 through the normally-closed
contacts 31 of a relay. The battery 30 forms part of power supply
circuit 32 which includes an integrated-circuit voltage regulator
33, which may be a 78Lo5. More specifically, the positive and
negative terminals of the battery 30 are respectively connected to
pins 1 and 2 of the voltage regulator 33, the positive battery
terminal being connected through the impact control ON-OFF switch
24. Connected across the input terminals of the voltage regulator
33 is the series combination of an LED 34 and a current-limiting
resistor 35, the LED 34 being illuminated when the switch 24 is
closed, signifying that the remainder of the battery pack circuitry
is powered. Capacitors 36 and 37 are connected in parallel across
the input terminals of the voltage regulator 33, while a capacitor
38 is connected across pin 2 and the output terminal at pin 3 of
the voltage regulator 33. The voltage regulator receives the B+
voltage of the battery 30 at its input and generates at its output
a V+ voltage, which may be 5VDC. Capacitors 37 and 38 quell
oscillations within the voltage regulator 33, while capacitor 36
prevents damage to the voltage regulator.
[0017] Also disposed in the battery pack housing 21 is a trigger
circuit 40 which, includes a vibrational or acoustic detector, such
as a microphone 41, connected across the V+ supply through a
resistor 42. The microphone 41 converts vibrations applied to the
battery pack 20 into electrical signals, the amplitude of which
varies proportionally to the magnitude of the vibration. The
microphone is connected through a coupling capacitor 43 and a
resistor 44 to the signal input of an IC comparator 45, which may
be a TLC372, the reference input of which is connected to the wiper
of a potentiometer 47 which is connected in series with a resistor
46 across the V+ supply. A noise-filtering capacitor 48 is
connected across the V+ supply at the supply input terminals of the
comparator 45. The output of the comparator 45 is connected through
a resistor 49 to a timer circuit 50. The capacitor 43 decouples DC
from the comparator 45. The potentiometer 47 is adjusted so that
the comparator 45 responds to vibrations caused by impacting of the
tool 10, but not vibrations of lesser magnitude.
[0018] The timer circuit 50 includes an integrated circuit dual
timer 51, which may be an MC14538B. V+ supply voltage is provided
to the dual timer 51 at pin 16, pin 8 being connected to ground.
The output of the trigger circuit 40 at pin 1 of the comparator 45
is connected to the input of the dual timer 51 at pin 4 thereof.
Pins 2-7 of the dual timer 51 are associated with a first timer for
controlling impact duration, while pins 9-15 are associated with a
second timer controlling the duration of battery disconnect.
Connected in series across the V+ supply are a resistor 52 and a
capacitor 53, the junction therebetween being connected to pins 3
and 13 of the dual timer 51. Also, connected in series across the
V+ supply are a potentiometer 54 and a capacitor 55, the junction
therebetween, as well as the wiper of the potentiometer 54, being
connected to pin 2 of the dual timer 51, while pin 1 is connected
to ground. Also connected in series across the V+ supply are a
resistor 56 and a capacitor 57, pins 14 and 15 of the dual timer 51
being connected to opposite terminals of the capacitor 57. Pins 5,
7 and 12 of the dual timer 51 are connected together, as are pins 9
and 11. Pin 16 is connected to ground through a capacitor 58. Pin 6
is not connected and the output of the dual timer 51 is at pin
10.
[0019] In operation, a transition from low (zero volts ) to high (5
volts) at the output of the comparator 45 starts the first timer,
causing pin 7 of the dual timer 51 to go low. The duration of the
first timer is determined by the value of the capacitor 55 and the
adjusted resistance across the potentiometer 54, this adjustment
being effected by the dial 25 (FIG. 2). The interconnection of pins
5 and 7 prevents any trigger signals at pin 4 from restarting the
first timer while it is on. Pin 7 is connected to pin 12 so that
when the first timer has timed out, a low-to-high transition at pin
12 will start the second timer. The duration of the second timer is
determined by the values of the resistor 56 and the capacitor 57
and is typically set at about one second, a time sufficient for the
operator to release the trigger 19. The interconnection of pins 9
and 11 prevents any trigger signals at pin 12 from restarting the
second timer while it is on. The resistor 52 and the capacitor 53,
connected to pins 3 and 13, serve as a power-on reset, insuring
that when the switch 24 is closed, both timers remain off until an
appropriate trigger signal is received from the trigger circuit
40.
[0020] Also disposed in the battery pack housing is a relay circuit
60. The output of the dual timer 51 at pin 10 is applied through a
resistor 61 to the base of a transistor 62, the emitter of which is
connected to ground and the collector of which is connected to the
anode of a diode 64, the cathode of which is connected to the B+
supply. The coil 65 of the relay is connected across the diode 64.
When pin 10 of the dual timer 51 is high, the transistor 62 is
turned on, with resistor 61 providing current limiting. This allows
current to flow through the coil 65 of the relay, opening the
normally-closed contacts 31 to disconnect the battery 30 from the
battery pack terminals 28. The diode 64 protects the circuitry from
voltage spikes generated by the relay when the transistor 62 turns
off.
[0021] In operation, if timed impact control is desired, the impact
control switch 24 is closed, powering the control circuitry of the
battery pack 20, which will be indicated by illumination of the LED
34. The setting of the potentiometer 54 is controlled by the dial
25. Since the time versus torque equation varies with joint
stiffness, friction and other variables, the appropriate time
interval for impacting must be determined prior to first use. This
could be done by setting the time interval to a minimum value,
operating the tool 10, then measuring the torque applied to the
associated fastener, and then increasing the time interval
incrementally and repeating the process until the measured torque
matches the desired value. Once determined, the same time interval
setting can then be used to obtain the same torque for similar
joints.
[0022] With the appropriate time interval is set, the tool 10 is
utilized for torquing a fastener in a normal fashion. When the user
pulls the trigger 19 the motor 13 is powered to start rotation of
the output drive square 17. In low-torque conditions, when the
fastener is spinning freely, the control circuitry of the battery
pack 20 is inactive. Once the fastener is seated and torque begins
to build up, the impact mechanism 14 begins to apply impact forces
to the fastener, in a known manner, the vibrations associated with
which are detected by the microphone 41, to start the first timer
of the dual timer 51, which will typically be set for a few
seconds, the normal impact time required to fully tightened a
fastener. When that time period expires, an output is produced at
pin 10 of the dual timer 51 for tripping the relay 65 and for
starting the second timer. Energization of the relay opens the
contacts 31 to disconnect the battery 30 from the motor 13,
whereupon the user will release the trigger 19, since the limiting
torque has been reached. At expiration of the second timer
interval, the transistor 62 is turned off and the contacts 31
reclosed, preparing the apparatus for the next torquing cycle.
[0023] If timed impact control is not desired, the battery pack 20
can be used in its normal manner by simply leaving the switch 24
open, as signified by the LED 34 being off, in which case the tool
10 will operate normally. The battery pack would typically be used
in this mode during a loosening of the fastener, where torque
limiting is not desired.
[0024] While the present invention is disclosed as used in
connection with a torque-applying impact tool, it will be
appreciated that it could be utilized with other types of impact
tools and, indeed, with electrically powered devices other than
impact tools, wherever an onset of a predetermined condition is
signified by generation of a detectable sound or vibration. Also,
while a microphone is used in the illustrated embodiment for
detection of the tool impacts, it will be appreciated that other
types of vibration sensing devices could be used.
[0025] 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 obvious 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.
* * * * *