U.S. patent application number 16/698232 was filed with the patent office on 2020-03-26 for system and method to divert inductive energy from cells.
The applicant listed for this patent is Black & Decker Inc.. Invention is credited to Tony J. AGRO, Michael FORSTER, Bhanu V. GORTI, Christopher HELD, Geoffrey S. HOWARD, Ralphy A. LOUIS, Robert J. MARCINKOWSKI, Nathan OSBORNE, Michael VARIPATIS, Daniel J. WHITE.
Application Number | 20200099109 16/698232 |
Document ID | / |
Family ID | 52479745 |
Filed Date | 2020-03-26 |
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United States Patent
Application |
20200099109 |
Kind Code |
A1 |
OSBORNE; Nathan ; et
al. |
March 26, 2020 |
System And Method To Divert Inductive Energy From Cells
Abstract
A power tool/battery pack combination includes an electric
motor, one or more electrochemical cells, and a capacitive element.
The electric motor is connected in series to a first switch. The
series combination of the electric motor and the first switch is
connected to a first terminal and a second terminal. The one or
more electrochemical cells are connected across a third terminal
and a fourth terminal. The third terminal and the fourth terminal
are coupled respectively to the first terminal and the second
terminal. The one or more electrochemical cells supply power to the
electric motor via the first switch. The capacitive element
includes one or more capacitors. The capacitive element is
connected across the third terminal and the fourth terminal. The
capacitive element is capable of storing inductive energy generated
by the one or more electrochemical cells.
Inventors: |
OSBORNE; Nathan; (Baltimore,
MD) ; MARCINKOWSKI; Robert J.; (Towson, MD) ;
HELD; Christopher; (Abbottstown, PA) ; LOUIS; Ralphy
A.; (York, PA) ; WHITE; Daniel J.; (Baltimore,
MD) ; FORSTER; Michael; (White Hall, MD) ;
GORTI; Bhanu V.; (Abingdon, MD) ; HOWARD; Geoffrey
S.; (Columbia, MD) ; AGRO; Tony J.; (San
Antonio, TX) ; VARIPATIS; Michael; (Fallston,
MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Black & Decker Inc. |
New Britain |
CT |
US |
|
|
Family ID: |
52479745 |
Appl. No.: |
16/698232 |
Filed: |
November 27, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13974504 |
Aug 23, 2013 |
10511067 |
|
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16698232 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M 10/4264 20130101;
H02P 7/00 20130101; H02J 7/345 20130101 |
International
Class: |
H01M 10/42 20060101
H01M010/42; H02P 7/00 20060101 H02P007/00 |
Claims
1. A power tool and battery pack combination comprising: a power
tool including an electric motor connected in series to a first
switch, the series combination of the electric motor and the first
switch connected to a first terminal and a second terminal; and a
battery pack including one or more electrochemical cells connected
across a third terminal and a fourth terminal, the third terminal
and the fourth terminal coupled respectively to the first terminal
and the second terminal, wherein the one or more electrochemical
cells supply power to the electric motor via the first switch; and
a capacitive element including one or more capacitors, the
capacitive element connected across the third terminal and the
fourth terminal, the capacitive element capable of storing
inductive energy generated by the one or more electrochemical
cells.
2. The combination of claim 1 wherein the capacitive element
prevents the inductive energy from being applied to the first
switch in response to the motor being operated at varying
speeds.
3. The combination of claim 1 wherein a value of the capacitive
element depends on a voltage supplied by the one or more
electrochemical cells and a chemical composition of the one or more
electrochemical cells.
4. The combination of claim 1 wherein: the one or more
electrochemical cells are connected in series, in parallel, or
using a combination of series and parallel connections; and the one
or more capacitors are connected in series, in parallel, or using a
combination of series and parallel connections.
5. The combination of claim 1 further comprising a fuse coupled to
the one or more capacitors, wherein the fuse transforms into an
open circuit when one of the one or more capacitors associated with
the fuse malfunctions.
6. The combination of claim 1 further comprising: a second switch
connected in series with the first switch, wherein the second
switch has a higher power rating than the first switch; and a
controller to control the second switch, wherein the controller
opens the second switch to stop supply of power from the one or
more electrochemical cells to the electric motor when a
temperature, voltage, or current of the one or more electrochemical
cells crosses a predetermined threshold.
7. The combination of claim 1 wherein: an inductance of the one or
more electrochemical cells is a sum of inductances of each of the
one or more electrochemical cells; and a value of the inductance
depends on a design of the one or more electrochemical cells.
8. A battery pack for supplying power to a power tool, the battery
pack comprising: a housing having a first terminal and a second
terminal and configured to detachable couple to the power tool; at
least one electrochemical cell contained in the housing, a given
electrochemical cell having a given shape and connected across the
first terminal and the second terminal of the housing; a
compartment container contained in the housing, the container
having a shape equivalent to the given electrochemical cell with
dimensions equal to the given shape of the given electrochemical
cell; and two or more capacitors electrically coupled together and
contained in the container, where the two or more capacitors are
connected across the first terminal and the second terminal of the
housing.
9. The battery pack of claim 8 wherein the two or more capacitors
store inductive energy generated by the at least one
electrochemical cell.
10. The battery pack of claim 8 wherein a value of the two or more
capacitors depend on a voltage supplied by the at least one
electrochemical cells and a chemical composition of the at least
one electrochemical cells.
11. The battery pack of claim 8 wherein: there are at least two
electrochemical cells and the at least two electrochemical cells
are connected in series, in parallel, or using a combination of
series and parallel connections; and there are at least two
capacitors and the at least two capacitors are connected in series,
in parallel, or using a combination of series and parallel
connections.
12. The battery pack of claim 8 further comprising a fuse coupled
to the two or more capacitors, wherein the fuse transforms into an
open circuit when one of the two or more capacitors associated with
the fuse malfunctions.
13. The battery pack of claim 8 further comprising: a switch; and a
controller that opens the switch to stop supply of power from the
at least one electrochemical cells to a load when a temperature,
voltage, or current of the at least one electrochemical cells
crosses a predetermined threshold.
14. The battery pack of claim 8 wherein: an inductance of the at
least one electrochemical cells is a sum of inductances of each of
the at least one electrochemical cells; and a value of the
inductance depends on a design of the at least one electrochemical
cells.
15. A battery pack for a power tool, the battery pack comprising: a
capacitive element; at least one electrochemical cell, the at least
one electrochemical cell having a geometry; and a plurality of
compartments contained in a housing, each of the compartments
having a geometry equivalent to the geometry of the at least one
electrochemical cell, wherein the capacitive element and the at
least one electrochemical cell reside in respective compartments of
the battery pack.
16. The battery pack of claim 15 wherein the capacitive element
includes at least one capacitor, wherein the capacitive element is
connected across a first terminal and a second terminal of the
housing, and wherein the capacitive element stores inductive energy
generated by the at least one electrochemical cell.
17. A power tool and battery pack combination comprising: an
electric motor arranged in a first housing, the first housing
including a first terminal and a second terminal to receive power
to drive the electric motor; at least one electrochemical cell
arranged in a second housing, the second housing including a third
terminal and a fourth terminal coupled respectively to the first
terminal and the second terminal of the first housing, the at least
one electrochemical cell connected across the third terminal and
the fourth terminal; a first switch residing in the first housing,
the first switch connecting the at least one electrochemical cell
to the electric motor responsive to a first control signal; a first
controller residing in the first housing, the first controller
generating the first control signal; and a capacitive element
residing in the second housing.
18. The combination of claim 17 wherein the capacitive element
includes at least one capacitor, wherein the capacitive element is
connected across the third terminal and the fourth terminal of the
second housing, and wherein the capacitive element stores inductive
energy generated by the at least one electrochemical cell thereby
preventing the inductive energy from being applied to the first
switch.
19. The combination of claim 17, wherein: the at least one
electrochemical cell has a geometry; a plurality of compartments
contained in the second housing, each of the plurality of
compartments having a geometry equivalent to the geometry of the at
least one electrochemical cell; the capacitive element resides in a
first one of the plurality of compartments; and the at least one
electrochemical cell resides in a second one of the plurality of
compartments.
20. The combination of claim 17 wherein a value of the capacitive
element depends on a voltage supplied by the one or more
electrochemical cells and a chemical composition of the one or more
electrochemical cells.
21. The combination of claim 17 wherein: there are at least two
electrochemical cells and the at least two electrochemical cells
are connected in series, in parallel, or using a combination of
series and parallel connections; and there are at least two
capacitors and the at least two capacitors are connected in series,
in parallel, or using a combination of series and parallel
connections.
22. The combination of claim 17 further comprising a fuse coupled
to one or more capacitors of the capacitive element, wherein the
fuse transforms into an open circuit when one of the one or more
capacitors associated with the fuse malfunctions.
23. The combination of claim 17 further comprising: a second switch
residing in the second housing, wherein the second switch is
connected in series with the first switch, wherein the second
switch has a higher power rating than the first switch; and a
second controller residing in the second housing, the second
controller generating a second control signal when a temperature,
voltage, or current of the one or more electrochemical cells
crosses a predetermined threshold, wherein the second controller
opens the second switch to stop supply of power from the one or
more electrochemical cells to the electric motor based on the
second control signal.
Description
FIELD
[0001] The present disclosure relates generally to a battery pack
and more particularly to a technique for diverting inductive energy
from the cells of the battery pack away from components connecting
the battery pack to a load.
BACKGROUND
[0002] Battery packs can be used with a variety of devices. These
devices include power tools. Power tools are of many types.
Examples of power tools include drills, drill/drivers, hammer
drill/drivers, rotary hammers, screwdrivers, impact drivers,
circular saws, jig saws, reciprocating saws, band saws, cut-off
tools, cut-out tools, shears, sanders, vacuums, adhesive
dispensers, concrete vibrators, staplers, nailers, flashlights,
radios, and lasers.
[0003] Power tools typically receive electrical power from a wall
outlet or from the battery pack that is removably coupled to the
power tools. The battery pack may include one or more
electrochemical cells (hereinafter "cells"). The cells can be of
different types. For example, the battery pack may include
nickel-cadmium (NiCd) cells or lithium-ion (Li-ion) cells.
[0004] The power tools typically include a motor and a switch that
is used to vary the speed of the motor. During variable speed mode,
the switch is typically turned on and off (closed and opened) using
pulse width modulated signals. The speed of the motor is varied by
varying a duty cycle of the pulse width modulated signals. The
circuitry that generates the pulse width modulated signals may be
included in the tool portion or the battery back portion of the
power tool. Some power tools may not have the variable speed
feature and may simply have on/off mode.
[0005] One of the electrical characteristics of the cells is that
each cell has an inductance. The value of the inductance depends on
the chemical composition and mechanical construction of the cell.
Due to the inductance of the cell, an inductive energy builds up in
the cell while the switch is closed. When the battery or tool
switch is turned off, the inductive energy typically dissipates
across the tool or battery switch and heats the switch. Depending
on the value of the inductance, the frequency and the duty cycle at
which the switch is turned on and off by the pulse width modulated
signal, the heat generated by the inductive energy can cause the
switch to malfunction.
[0006] Therefore, in order to prevent the switch from heating and
malfunctioning, it is desirable to provide a protective device that
will divert the inductive energy from the cells of the battery
pack. The protective device can prevent the inductive energy from
dissipating across the switch, thereby preventing the switch from
malfunctioning.
[0007] The statements in this section merely provide background
information related to the present disclosure and may not
constitute prior art.
SUMMARY
[0008] In one embodiment, a power tool and battery pack combination
comprises a power tool including an electric motor connected in
series to a first switch. The series combination of the electric
motor and the first switch is connected to a first terminal and a
second terminal. The combination also comprises a battery pack
including one or more electrochemical cells connected across a
third terminal and a fourth terminal. The third terminal and the
fourth terminal are coupled respectively to the first terminal and
the second terminal. The one or more electrochemical cells supply
power to the electric motor via the first switch. A capacitive
element including one or more capacitors is connected across the
third terminal and the fourth terminal. The capacitive element is
capable of storing inductive energy generated by the one or more
electrochemical cells.
[0009] The capacitive element prevents the inductive energy from
being applied to the first switch in response to the motor being
operated at varying speeds. A value of the capacitive element
depends on a voltage supplied by the one or more electrochemical
cells and a chemical composition of the one or more electrochemical
cells. The one or more electrochemical cells are connected in
series, in parallel, or using a combination of series and parallel
connections. The one or more capacitors are connected in series, in
parallel, or using a combination of series and parallel
connections.
[0010] The combination further comprises a fuse coupled to the one
or more capacitors. The fuse transforms into an open circuit when
one of the one or more capacitors associated with the fuse
malfunctions. The combination further comprises a second switch
connected in series with the first switch. The second switch has a
higher power rating than the first switch. The combination further
comprises a controller to control the second switch. The controller
opens the second switch to stop the supply of power from the one or
more electrochemical cells to the electric motor when a
temperature, voltage, or current of the one or more electrochemical
cells crosses a predetermined threshold. An inductance of the one
or more electrochemical cells is a sum of inductances of each of
the one or more electrochemical cells. A value of the inductance
depends on a design of the one or more electrochemical cells.
[0011] In another embodiment, a battery pack for supplying power to
a power tool comprises a housing. At least one electrochemical cell
is contained in the housing. The at least one electrochemical cell
has a geometry and is connected across a first terminal and a
second terminal of the housing. A compartment contained in the
housing has a geometry equivalent to the geometry of the at least
one electrochemical cell. A capacitive element is contained in the
housing. The capacitive element includes at least one capacitor.
The capacitive element is connected across the first terminal and
the second terminal of the housing. The capacitive element stores
inductive energy generated by the at least one electrochemical
cell. A value of the capacitive element depends on a voltage
supplied by the at least one electrochemical cell and a chemical
composition of the at least one electrochemical cell. In yet
another embodiment, there are at least two electrochemical cells
and the at least two electrochemical cells are connected in series,
in parallel, or using a combination of series and parallel
connections. There are at least two capacitors and the at least two
capacitors are connected in series, in parallel, or using a
combination of series and parallel connections.
[0012] The battery pack further comprises a fuse coupled to one or
more capacitors of the capacitive element. The fuse transforms into
an open circuit when one of the one or more capacitors associated
with the fuse malfunctions. The battery pack further comprises a
switch and a controller that opens the switch to stop the supply of
power from the at least one electrochemical cell to a load when a
temperature, voltage, or current of the at least one
electrochemical cell crosses a predetermined threshold. An
inductance of the at least one electrochemical cell is a sum of
inductances of each of the at least one electrochemical cell. A
value of the inductance depends on a design of the at least one
electrochemical cell.
[0013] In another embodiment, a battery pack for a power tool
comprises a capacitive element, at least one electrochemical cell
having a geometry, and a plurality of compartments contained in a
housing. Each of the compartments has a geometry equivalent to the
geometry of the at least one electrochemical cell. The capacitive
element and the at least one electrochemical cell reside in
respective compartments of the battery pack. The capacitive element
includes at least one capacitor. The capacitive element is
connected across a first terminal and a second terminal of the
housing. The capacitive element stores inductive energy generated
by the at least one electrochemical cell.
[0014] In another embodiment, a power tool and battery pack
combination comprises an electric motor arranged in a first
housing. The first housing includes a first terminal and a second
terminal to receive power to drive the electric motor. At least one
electrochemical cell is arranged in a second housing. The second
housing includes a third terminal and a fourth terminal coupled
respectively to the first terminal and the second terminal of the
first housing. The at least one electrochemical cell is connected
across the third terminal and the fourth terminal. A first switch
resides in the first housing. The first switch connects the at
least one electrochemical cell to the electric motor responsive to
a first control signal. A first controller resides in the first
housing. The first controller generates the first control signal. A
capacitive element resides in the second housing.
[0015] The capacitive element includes at least one capacitor. The
capacitive element is connected across the third terminal and the
fourth terminal of the second housing. The capacitive element
stores inductive energy generated by the at least one
electrochemical cell thereby preventing the inductive energy from
being applied to the first switch. The at least one electrochemical
cell has a geometry. A plurality of compartments is contained in
the second housing. Each of the plurality of compartments has a
geometry equivalent to the geometry of the at least one
electrochemical cell. The capacitive element resides in a first one
of the plurality of compartments. The at least one electrochemical
cell resides in a second one of the plurality of compartments. A
value of the capacitive element depends on a voltage supplied by
the at least one electrochemical cell and a chemical composition of
the at least one electrochemical cell. In yet another embodiment,
there are at least two electrochemical cells and the at least two
electrochemical cells are connected in series, in parallel, or
using a combination of series and parallel connections. There are
at least two capacitors and the at least two capacitors are
connected in series, in parallel, or using a combination of series
and parallel connections.
[0016] The combination further comprises a fuse coupled to one or
more capacitors of the capacitive element. The fuse transforms into
an open circuit when one of the one or more capacitors associated
with the fuse malfunctions. The combination further comprises a
second switch residing in the second housing. The second switch is
connected in series with the first switch. The second switch has a
higher power rating than the first switch. A second controller
resides in the second housing. The second controller generates a
second control signal when a temperature, voltage, or current of
the one or more electrochemical cells crosses a predetermined
threshold. The second controller opens the second switch to stop
the supply of power from the at least one electrochemical cell to
the electric motor based on the second control signal.
[0017] Further areas of applicability of the present disclosure
will become apparent from the detailed description, the claims and
the drawings. The detailed description and specific examples are
intended for purposes of illustration only and are not intended to
limit the scope of the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The present disclosure will become more fully understood
from the detailed description and the accompanying drawings,
wherein:
[0019] FIG. 1 is a diagram of an exemplary system of power
tools;
[0020] FIG. 2 is a functional block diagram of a power tool
including a battery pack;
[0021] FIG. 3 is a functional block diagram of a power tool
including a battery pack that has a capacitive element;
[0022] FIG. 4A shows different arrangements of capacitors in the
capacitive element;
[0023] FIG. 4B shows different arrangements of electrochemical
cells in a battery pack;
[0024] FIG. 5A is a functional block diagram of a power tool, where
the tool and the battery pack include respective control
modules;
[0025] FIG. 5B is a functional block diagram of a power tool, where
the tool includes a control module, and where the battery pack does
not include a control module;
[0026] FIG. 5C is a functional block diagram of a power tool, where
the battery pack includes a control module, and where the tool does
not include a control module; and
[0027] FIG. 6 is a flowchart of a method for diverting inductive
energy from cells of a battery pack to a capacitive element
connected across the battery pack.
[0028] FIGS. 7A-7F show an example of an arrangement of
electrochemical cells and the capacitive element in the battery
pack.
[0029] The drawings described herein are for illustration purposes
only and are not intended to limit the scope of the present
disclosure in any way.
[0030] In the drawings, reference numbers may be reused to identify
similar and/or identical elements.
DETAILED DESCRIPTION
[0031] FIG. 1 shows a system 10 of power tools. The system 10 of
power tools can include, for example, one or more power tools 12, a
battery pack 16, and a battery pack charger 18. Each of the power
tools 12 can be any type of power tool, including without
limitation drills, drill/drivers, hammer drill/drivers, rotary
hammers, screwdrivers, impact drivers, circular saws, jig saws,
reciprocating saws, band saws, cut-off tools, cut-out tools,
shears, sanders, vacuums, adhesive dispensers, concrete vibrators,
staplers, nailers, flashlights, radios, and lasers.
[0032] In the example shown, the system 10 of power tools includes
a first power tool 12a and a second power tool 12b. For example,
the first power tool 12a can be a drill/driver similar to that
which is described in U.S. Pat. No. 6,431,289, while the second
power tool 12b can be a circular saw similar to that which is
described in U.S. Pat. No. 6,996,909. The battery pack 16 can be
selectively removably coupled to the first and second power tools
12a and 12b to provide electrical power thereto. Except as
otherwise described herein, the battery pack 16 can be configured
in a manner that is similar to that which is described in U.S. Pat.
Nos. 7,273,759 and 7,508,171. The battery pack 16 can also be
selectively electrically coupled to the battery pack charger 18 to
charge the battery pack 16. It is noteworthy that the broader
aspects of this disclosure are applicable to battery packs for
other types of battery powered devices (e.g., flashlights, radios,
and lasers).
[0033] FIG. 2 shows an embodiment of a power tool/battery pack
combination 100 including a battery pack that does not have a
capacitive element. The combination 100 includes a power tool 102
and a battery pack 104. The power tool 102 and the battery pack 104
may be enclosed in separate housings. The power tool 102 includes a
motor 106 and a switch 108. A freewheeling diode 110 may be
connected across the motor 106. While not shown, a freewheeling
diode may be connected across the battery pack 104 as well, to
handle cases, for example, where the power tool has no freewheeling
diode and the motor's inductive energy could damage a switch in the
battery pack 104.
[0034] The battery pack 104 includes one or more electrochemical
cells (hereinafter cells) 112 and may include a switch 114. The
cells 112 may be connected to each other in series, in parallel, or
using a combination of series and parallel connections. Each of the
cells 112 has an intrinsic inductance. An effective inductance of
the cells 112 is shown as an inductance 116 connected in series
with the cells 112. The inductance 116 shown is an intrinsic
inductance of the cells 112 and is shown externally connected to
the cells 112 for illustrative purposes only.
[0035] In use, the battery pack 104 is connected to the power tool
102. The cells 112 supply power to the motor 106 through the
switches 114 and 108. The switch 114 is closed when the power tool
102 is operated. The switch 114 can be opened and the power supply
from the cells 112 to the motor 106 can be disconnected when a
sensor (not shown for simplicity of illustration) senses that a
temperature, voltage, or current of one or more cells 112 crosses a
predetermined threshold. The switch 108 can be operated to vary the
speed of the motor 106. For example, the switches 114 and 108 may
be further defined as field effect transistors (FETs). The switch
108 may be driven by pulse width modulated signals having a duty
cycle. The speed of the motor 106 can be varied by varying the duty
cycle of the pulse width modulated signals. The switch 108 can also
be in bypass mode, where the PWM circuit is not in use (e.g., if
the trigger of the power tool 102 is fully depressed).
[0036] While the speed of the motor 106 is varied, each time the
switch 108 turns on (closes), the inductive energy that is already
built up in the cells 112 when the switch 108 is turned off,
typically dissipates across the switch 108, thereby heating the
switch 108. The inductive energy may also dissipate across the
switch 114 and/or other circuit components. Depending on the value
of the inductance 116 of the cells 112 and depending on the duty
cycle at which the switch 108 is turned on and off, the switch 108
(and/or other circuit components) can heat excessively and/or
malfunction. The value of the inductance 116 depends primarily on
the design and construction of the cells 112.
[0037] FIG. 3 shows an embodiment of a power tool/battery pack
combination 200 including a battery pack that has a capacitive
element. The combination 200 includes the power tool 102 and a
battery pack 204. The battery pack 204 includes all of the
components of the battery pack 104. Additionally, the battery pack
204 includes a capacitive element 206. The capacitive element 206
may include one or more capacitors. The capacitors may be connected
to each other in series, in parallel, or using a combination of
series and parallel connections. While the speed of the motor 106
is varied, each time the switch 108 turns off, the capacitors store
the inductive energy generated by the cells 112, thereby preventing
the inductive energy from being applied to the switch 108.
[0038] The inductive energy is dissipated at a natural frequency of
an RLC circuit formed by the capacitive element 206, the inductance
of the cells 112, and the internal resistance of the circuitry. The
use of the capacitive element 206 is not restricted to power tools
with variable speed. The capacitive element 206 can also be used
with power tools that are simple on/off type. When an on/off type
power tool shuts off, the capacitive element 206 can be used to
absorb the inductive energy generated by the cells to prevent
damage to control circuitry of the on/off type power tool. In
general, the capacitive element 206 can be used to protect any
switch in a high current path in a circuit.
[0039] The value (i.e., the capacitance) of the capacitive element
206 may depend on the voltage rating of the cells 112. In addition,
the value of the capacitive element 206 may depend on the chemical
composition and mechanical construction of the cells 112. Each
capacitor in the capacitive element 206 may have a different value.
Alternatively, all of the capacitors in the capacitive element 206
may have the same value.
[0040] For example, consider a battery and tool system, where a
certain amount of energy J needs to be diverted to the capacitive
element 206. The energy, J, may be the avalanche energy of a MOSFET
when the MOSFET opens (turns off). The capacitance C of the
capacitive element 206 can be estimated by the maximum energy
stored by a capacitor: J=1/2CV.sup.2, where C is the capacitance of
the capacitor (the capacitive element 206), and V is the voltage
across the capacitor when the energy absorption needs to occur.
According to the present disclosure, the required capacitance of
the capacitive element 206 is primarily a function of the
inductance of each of the cells 112.
[0041] Suppose a battery with a first cell arrangement (e.g., 20v
at 4v per cell) has a total inductance of L and an already
determined capacitance C for the capacitive element 206. Assuming
the same cell is used, a battery with a second cell arrangement
(e.g., 16v at 4v per cell) would have 80% of the inductance first
cell arrangement, and a corresponding capacitance requirement of
approximately 0.80*C. A third cell arrangement (e.g., 12v at 4v per
cell) would have 60% of the first cell arrangement, and a
corresponding capacitance requirement of approximately 0.60*C.
Because the inductance is halved when cells are connected in
parallel, the first cell arrangement employing cells connected in
parallel with the same cell and tool system would theoretically
require 2*C capacitance, the second cell arrangement employing
cells connected in parallel with the same cell and tool system
would require 0.8*2*C capacitance, and so on.
[0042] A fuse may be associated with one or more capacitors in the
capacitive element 206. In the event that a capacitor malfunctions,
the fuse associated with the malfunctioning capacitor may open
thereby transforming the malfunctioning capacitor into an open
circuit, thereby effectively removing the malfunctioning capacitor
from the circuit. FIG. 4A (described below) shows an example
arrangement including the fuse.
[0043] The housing of the battery pack 204 may include a plurality
of compartments. Each compartment may have the same geometry. The
cells 112 may reside in one or more of the compartments. That is,
each of the cells 112 resides in a respective one of the
compartments. The capacitive element 206 can reside in any of the
compartments where one of the cells 112 can reside instead. In
other words, the compartment in which the capacitive element 206
resides has the same geometry as the compartment in which one of
the cells 112 resides. Accordingly, one of the cells 112 can be
removed from its compartment and can be substituted with an element
having the same geometry as the cell, where the element houses the
capacitive element 206. The electrical connections across the
compartments are arranged in such a manner so that the capacitive
element 206 is connected across (i.e., in parallel to) the cells
112.
[0044] In some implementations, the capacitive element 206 may not
have the shape of a cell and may not have the same geometry as the
compartment in which one of the cells 112 resides. Rather, the
capacitive element 206 may simply comprise a PCB and could reside
anywhere in the battery pack 204.
[0045] FIG. 4A shows examples of different arrangements that may be
used to connect the capacitors in the capacitive element 206. For
example, in the arrangement 206-1, the capacitors may be connected
to each other in series to form the capacitive element 206. As
another example, in the arrangement 206-2, the capacitors may be
connected to each other in parallel to form the capacitive element
206. Alternatively, a combination of series and parallel
connections of the capacitors may be used to form the capacitive
element 206. In some implementations, the capacitive element 206
may be connected across each of the cells 112.
[0046] FIG. 4B shows examples of different arrangements that may be
used to connect the cells 112. For example, in the arrangement
112-1, two or more cells may be connected to each other in series
to form the cells 112. As another example, in the arrangement
112-2, two or more cells may be connected to each other in parallel
to form the cells 112. Alternatively, a combination of series and
parallel connections of cells may be used to form the cells
112.
[0047] FIG. 5A shows an alternative embodiment of a power
tool/battery pack combination 300, where the tool and the battery
pack include respective control modules. The combination 300
includes a power tool 302 and a battery pack 304. The power tool
302 includes all of the components of the power tool 102.
Additionally, the power tool 302 includes a tool control module 306
and one or more sensors 308. The tool control module 306 generates
control signals to control the switch 108. For example, the control
signals may include pulse width modulated signals.
[0048] The sensors 308 may sense one or more conditions associated
with one or more components of the tool 302. For example, one of
the sensors 308 may sense a parameter associated with the motor
106. For example, the parameter may include a temperature of the
motor 106, current through the motor 106, and so on. As another
example, another one of the sensors 308 may sense a parameter
associated with the switch 108. For example, the parameter may
include a temperature of the switch 108, current through the switch
108, voltage across the switch 108, and so on.
[0049] The sensors 308 may output signals indicating the conditions
of the components of the tool 302 to the tool control module 306.
The tool control module 306 may control the switch 108 based on the
conditions of the components of the tool 302. For example, the tool
control module 306 may disable the switch 108 and stop power supply
from the cells 112 to the motor 106 if the temperature of the motor
106 and/or the temperature of the switch 108 crosses a
predetermined threshold.
[0050] The battery pack 304 may include all of the components of
the battery pack 204. Additionally the battery pack 304 may include
a battery pack control module 310 and one or more sensors 312. The
sensors 312 may sense one or more conditions of the components of
the battery pack 304. For example, the sensors 312 may sense one or
more conditions of the cells 112 and the capacitive element 206.
For example, one of the sensors 312 may sense the temperature of
the cells 112. Additionally, the sensors 312 may sense the voltage
and/or current supplied by the cells 112. Further, the sensors 312
may sense the number of capacitors operating in the capacitive
element 206 at a given time. For example, the number of capacitors
operating in the capacitive element 206 at a given time may depend
on the number of open circuit fuses at a given time. In addition,
the presence of the capacitive element 206 can be sensed through an
end of line test at the manufacturing facility.
[0051] The sensors 312 may output signals indicating the conditions
of the cells 112 and the capacitive element 206 to the battery pack
control module 310. The battery pack control module 310 may control
the switch 114 based on the conditions of the components of the
battery pack 304. For example, the battery pack control module 310
may disable the switch 114 and stop power supply from the cells 112
to the motor 106 if the temperature of the cells 112 crosses a
predetermined threshold, the number of open circuit fuses exceeds a
predetermined number, or the voltage and/or current of the cells
112 drops below a predetermined threshold.
[0052] FIG. 5B is a functional block diagram of a power tool 400,
where the tool includes a control module, and where the battery
pack does not include a control module. The power tool 400 includes
the tool 302 and the battery pack 204. The tool 302 operates as
described with reference to FIG. 5A. The battery pack 204 operates
as described with reference to FIG. 3 with the exception of
performing functions related to the switch 114.
[0053] Additional configurations of the tool and the battery pack
are contemplated. For example, in one configuration, a control
module that controls the motor and the switch in the tool may be
included in the battery pack instead of in the tool. FIG. 5C shows
such a configuration. In FIG. 5C, a functional block diagram of a
power tool 450 is shown, where the battery pack includes a control
module, and where the tool does not include a control module. The
power tool 450 includes the tool 102 and the battery pack 304. The
tool 102 operates as described with reference to FIGS. 2 and 3. The
battery pack 304 operates as described with reference to FIG. 4A
and additionally performs the functions of the tool control module
306 shown in FIG. 5B. Further, the present disclosure uses the
switches 108 and 114 only as examples of circuit components that
may be protected using the capacitive element 206. The capacitive
element 206 may be used to protect other circuit components from
the inductive energy of the cells 112. In some embodiments, the
capacitor array may be integrated into the power tool and not in a
separate battery pack. That is, the battery may reside in the power
tool.
[0054] FIG. 6 is a flowchart of a method 500 for operating a power
tool by diverting inductive energy from cells of a battery pack to
a capacitive element connected across the battery pack. At 502, a
user varies the speed of the tool motor. At 504, when the speed of
the tool motor is being varied (or when a simple on/off tool is
turned off, or when the tool trigger is fully depressed in bypass
mode and is released), the method 500 diverts inductive energy
generated by the cells to the capacitive element connected across
the cells, thereby preventing excessive inductive energy from being
applied across the tool switch. In some implementations, at 506,
the method 500 senses one or more conditions of one or more
components of the battery pack and/or the tool. At 508, the method
determines if a condition of a component of the battery pack and/or
the tool is within a predetermined range. The method 500 returns to
502 if the conditions of the components of the battery pack and the
tool are within the respective predetermined ranges. At 510, if a
condition of a component of the battery pack and/or the tool is not
within a predetermined range, the method 500 stops the power supply
from the cells to the tool motor.
[0055] FIGS. 7A-7F show an example of an arrangement of
electrochemical cells and the capacitive element in the battery
pack. In FIG. 7A, a battery pack (e.g., battery pack 204 or 304)
including a capacitive element (e.g., capacitive element 206)
according to the present disclosure is shown. In FIG. 7B, the
battery pack includes the cells 112 and the capacitive element 206.
In FIGS. 7C-7E, the capacitive element 206 is shown in detail. In
particular, the geometry of the capacitive element 206 is the same
as that of any of the cells 112. In FIG. 7F, the capacitive element
206 is shown coupled to the cells 112.
[0056] The foregoing description is merely illustrative in nature
and is in no way intended to limit the disclosure, its application,
or uses. The broad teachings of the disclosure can be implemented
in a variety of forms. Therefore, while this disclosure includes
particular examples, the true scope of the disclosure should not be
so limited since other modifications will become apparent upon a
study of the drawings, the specification, and the following claims.
As used herein, the phrase at least one of A, B, and C should be
construed to mean a logical (A or B or C), using a non-exclusive
logical OR. It should be understood that one or more steps within a
method may be executed in different order (or concurrently) without
altering the principles of the present disclosure.
[0057] In this application, including the definitions below, the
term module may be replaced with the term circuit. The term module
may refer to, be part of, or include an Application Specific
Integrated Circuit (ASIC); a digital, analog, or mixed
analog/digital discrete circuit; a digital, analog, or mixed
analog/digital integrated circuit; a combinational logic circuit; a
field programmable gate array (FPGA); a processor (shared,
dedicated, or group) that executes code; memory (shared, dedicated,
or group) that stores code executed by a processor; other suitable
hardware components that provide the described functionality; or a
combination of some or all of the above, such as in a
system-on-chip.
[0058] The term code, as used above, may include software,
firmware, and/or microcode, and may refer to programs, routines,
functions, classes, and/or objects. The term shared processor
encompasses a single processor that executes some or all code from
multiple modules. The term group processor encompasses a processor
that, in combination with additional processors, executes some or
all code from one or more modules. The term shared memory
encompasses a single memory that stores some or all code from
multiple modules. The term group memory encompasses a memory that,
in combination with additional memories, stores some or all code
from one or more modules. The term memory may be a subset of the
term computer-readable medium. The term computer-readable medium
does not encompass transitory electrical and electromagnetic
signals propagating through a medium, and may therefore be
considered tangible and non-transitory. Non-limiting examples of a
non-transitory tangible computer readable medium include
nonvolatile memory, volatile memory, magnetic storage, and optical
storage.
[0059] The apparatuses and methods described in this application
may be partially or fully implemented by one or more computer
programs executed by one or more processors. The computer programs
include processor-executable instructions that are stored on at
least one non-transitory tangible computer readable medium. The
computer programs may also include and/or rely on stored data.
* * * * *