Abstract:
A power tool an electric motor retained within a housing. A rechargeable battery is retained within the housing that is operatively connected to the electric motor. A power input port is supported within the housing that is operatively connected to the rechargeable battery. The power input port is configured to supply power to the rechargeable battery from an external power source. The rechargeable battery comprises a lithium based battery, and the power input port comprises a universal serial bus (USB) port configured to receive a USB connector.

Description:
RELATED APPLICATION DATA 
       [0001]    This application is related to Provisional Patent Application Ser. No. 61/668,623 filed on Jul. 6, 2012, and priority is claimed for this earlier filing under 35 U.S.C. §119(e). The Provisional Patent Application is also incorporated by reference into this utility patent application. 
     
    
     TECHNICAL FIELD 
       [0002]    This disclosure relates to power tools, and, in particular, to power tools configured to use rechargeable batteries. 
       BACKGROUND 
       [0003]    In general, cordless power tools refer to power tools that are adapted to receive power from a rechargeable battery that is either permanently or removably attached to the power tool. Many types of power tools have been adapted to receive power from rechargeable batteries, including various types of saws, drills, drivers, hammers, oscillating tools, and the like. Rechargeable batteries for cordless power tools, such as nickel cadmium (NiCad) based batteries or lithium based batteries, are typically designed to produce a particular output voltage, e.g., 3.6V, 7.2V, 9.6V, 12V, 14.4V, 18V, or 24V. Higher voltage batteries are used in power tools that have higher power requirements, and vice versa. 
         [0004]    Cordless power tools provide portability and convenience advantages over corded tools, but the rechargeable batteries that power them become depleted and need to be recharged. Cordless power tools are usually provided with a battery charger that is configured to recharge the batteries for the power tool. Battery chargers are typically configured to utilize AC power received via a conventional AC outlet, although some battery chargers may be equipped to use a vehicle&#39;s 12-volt DC power outlet. Therefore, to ensure continuous power tool usage, the user of a cordless power tool must carry the battery charger along with the tool and have access to an appropriate outlet. AC power outlets, however, are often located in distant, inconvenient, and/or inaccessible locations relative to the work area which makes it difficult to recharge the tool&#39;s battery when needed. 
         [0005]    There is a need for cordless power tools that are capable of being charged using a more readily available power source, such as low voltage power sources and, in particular, universal serial bus (USB) power sources. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0006]      FIG. 1  is a block diagram of a cordless power tool and USB charging system according to the present disclosure. 
           [0007]      FIG. 2  is a block diagram of an alternative embodiment of a cordless power tool and USB charging system according to the present disclosure. 
           [0008]      FIG. 3  is a side view of an embodiment of a power tool configured for USB charging with a portion of the housing removed. 
           [0009]      FIG. 4  is a perspective view of the power tool of  FIG. 3 . 
           [0010]      FIG. 5  is a bottom view of the power tool of  FIG. 3 . 
           [0011]      FIG. 6  is a side view of an embodiment of a power tool similar to  FIG. 3  with half of the clamshell housing removed to show the internal components of the tool. 
           [0012]      FIG. 7  is a perspective view of the power tool of  FIG. 6 . 
           [0013]      FIG. 8  is a partial view of the power tool of  FIG. 6  showing the Micro-USB port of the power tool. 
           [0014]      FIG. 9  is a perspective view of a Micro-USB connector for supplying power to the power tool of  FIGS. 3-8  via the Micro-USB port. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation to the scope of the disclosure is thereby intended. It is further understood that the present disclosure includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the disclosure as would normally occur to one of ordinary skill in the art to which this disclosure pertains. 
         [0016]    The present disclosure is directed to cordless power tools that are adapted to utilize USB power for charging the rechargeable batteries. By enabling power tools to be charged via a standard USB interface, power tools may be charged from any location that includes a computer, laptop, or USB power supply device. In addition, the proliferation of USB compliant devices means that USB power adapters and cords are in abundance and readily available when needed. 
         [0017]      FIG. 1  depicts a block diagram of the main components of a cordless power tool and USB charging system in accordance with the present disclosure. The cordless power tool includes a motor  110  adapted to drive a work element  112 . The work element  112  is part of the tool that performs the work on a work piece, such as cutting, sanding, grinding, boring, and driving. Therefore, the work element  112  may comprise a saw blade, a sanding disc, a grinding wheel, a drill bit, a wrench, and the like. The motor  110  comprises an electric motor that is coupled to the work element through a drive member (not shown), such as an output shaft. The power output of the electric motor  110  depends on the type of work element that it is configured to drive and the desired level of work, e.g., heavy duty or light duty. 
         [0018]    The electric motor  110  is operatively coupled to and powered by a rechargeable battery  108 . The rechargeable battery  108  may be removably attached to the power tool or may be built into the housing of the power tool. The rechargeable battery may comprise any suitable type of rechargeable battery, such as nickel cadmium (NiCad) or lithium based batteries. The rechargeable battery is configured to produce an output voltage that is capable of powering the electric motor. Depending on the type of motor and the desired work level, the rechargeable battery may have an output voltage of 3.6V, 7.2V, 9.6V, 12V, 14.4V, 18V, or 24V although any suitable battery voltage may be used. In one embodiment, the rechargeable battery comprises a lithium based battery, such as a lithium-ion cell battery. Lithium-ion cells are typically lighter and have a much slower self-discharge rate than energy-equivalent batteries of other types. 
         [0019]    A battery charger  104  is configured to recharge the rechargeable battery  108 . The battery charger  104  includes a charging circuit that is coupled to the rechargeable battery to supply energy to the battery in order to recharge the battery. The charging circuit may have any suitable configuration capable of charging the rechargeable battery. The implementation of the charging circuit depends at least partially on the type of battery. 
         [0020]    In embodiments in which the rechargeable battery  108  is removable from the power tool, the battery charger may include a cradle or stand including one or more receptacles for receiving a rechargeable battery after it has been removed from the power tool. In this embodiment, the battery charger and the rechargeable battery include complementary electrical terminals that cooperate to couple the battery to the charging circuit when the battery is installed in the charger and to decouple the charging circuit from the battery when the battery is removed from the charger. In embodiments in which the battery charger is built into the housing of the power tool, the charging circuit of the battery charger is permanently wired to the rechargeable battery. 
         [0021]    In accordance with the present disclosure, the battery charger  104  and charging circuit are configured to receive and utilize USB power to charge the rechargeable battery  108 . USB is a standard that defines the cables, connectors, and communication protocols for connection, communication, and power supply between computers and electronic devices. There are four USB specifications—USB 1.x, USB 2.0, USB 3.0, USB 4.0 or newer specification. The USB 1.x and 2.0 specifications require that a supply voltage for powering USB devices be no less than 4.75 V and no more than 5.25V (i.e., 5V±5%) and a maximum current for powering USB devices be no more than 500 mA. The USB 3.0 specification requires that the supply voltage for powering USB devices be no less than 4.45 V and no more than 5.25V and a maximum current for powering USB devices be no more than 900 mA. The charging circuit of the battery charger  104  is configured to receive USB power provided in accordance with one of the USB specifications, e.g., USB 3.0, and to utilize the USB power to recharge the rechargeable battery. 
         [0022]    A USB interface  102  is used to couple the battery charger  104  and charging circuit to the USB power source  100 . The USB interface  102  includes a standard USB connector and a standard USB port. The USB port is provided in the battery charger  104 , and the USB connector is provided at one end of a cable that is electrically coupled at the other end to a USB power source  100 . The USB connector and USB port may be any suitable USB connector and port type as defined by the USB specifications. For example, in one embodiment, the USB connector comprises Micro USB connector and the USB port comprises a Micro USB port. In alternative embodiments, any type of USB connector and USB port may be used. 
         [0023]    The cable of the USB interface  102  electrically connects the USB connector to a USB power source  100 . In one embodiment, the cable includes an AC adapter and plug at the other end that enables the USB power to be derived from a conventional AC outlet. Alternatively, the cable may include a second USB connector that is connected to a USB port of a computer, laptop, or other device that is capable of providing USB power including an AC adapter and plug that is provided with a USB port. When the USB connector is received in the USB port of the battery charger, the charging circuit is electrically coupled to receive USB power from the USB power source and to use the USB power to charge the rechargeable battery. 
         [0024]    The charging circuit in  FIG. 1  is only configured to utilize a single power source, i.e., the USB power source. In alternative embodiments, the battery charger and charging circuit may be configured to utilize other power sources in addition to USB power to charge the battery. For example, as depicted in  FIG. 2 , the battery charger  104  may be configured to be connected to an AC/DC power source  114  such as AC power source including an AC adapter and plug and/or a DC power source having a vehicle power adapter connected to the battery charger via an AC/DC interface  116 . In this embodiment, separate charging circuits may be provided in the battery charger for each power source and a control circuit may be configured to determine which power source to use if more than one power source is connected, such as if a USB power source and an AC power source are each connected to the battery charger at the same time. 
         [0025]      FIGS. 3-5  depict one embodiment of a power tool  10  adapted for USB charging.  FIGS. 6 and 7  depict an embodiment of a power tool  10  similar to the power tool of  FIGS. 3-5  with a portion of the housing removed to show the internal components of the tool. The embodiments of  FIGS. 3-7  are intended to be non-limiting examples showing a method of configuring a power tool to utilize USB power. The power tool  10  of  FIGS. 3-7  comprises a cordless driver configured to drive complementarily configured accessory tools and tool bits. The cordless driver  10  includes a housing  12  having a motor housing portion  14  and a pistol grip portion  16 . In one embodiment, the motor housing portion  14  and grip portion  16  are formed of two half-shells which are can be joined together by fasteners, such as screws. 
         [0026]    An electric motor  18  is mounted in the motor housing portion  14 . In embodiments in which the housing is formed by two half-shells, the motor is held in position and braced without play in the motor housing portion  14  by shaped ribs and walls (not shown) provided in each shell. The motor  18  includes a motor output shaft  20  that extends forwardly from the motor to engage a gearbox  22  mounted onto the front portion of the motor housing  14  and forms the nose of the power tool  10 . The gearbox  22  houses a planetary gear system (not shown) that is configured to be driven by the output shaft  20 . 
         [0027]    A power takeoff spindle  24  protrudes from the front of the gearbox  22  that is configured to be driven to rotate by the planetary gear system (not shown) of the gearbox  22 . The spindle  24  includes a tool holding portion  26  that is configured to removably retain various complementarily configured accessory tools and tools bits onto the spindle  24 . In one embodiment, the tool holding portion  26  of the spindle  24  comprises a hexagon-shaped socket configured to receive similarly sized hexagon-shaped accessories and tool bits, such as bit  25 . 
         [0028]    A ON/OFF trigger  28  is located on the pistol grip portion  16  of the housing  12  for controlling the operation of the motor  18 . Referring to  FIGS. 6 and 7 , the trigger  28  includes a contact plate  30  that forms an ON/OFF switch in conjunction with counterpart contacts  32  fixedly located in the tool  10 . When the trigger  28  is pressed inwardly, the contact plate  30  contacts the counterpart contact  32  and closes the power circuit which provides power to the motor  18 . When the trigger  28  is released, the contact plate  30  is moved away from the counterpart contact  32  thereby opening the power circuit and cutting off power to the motor  18 . Biasing members, such as springs  34 , are used to bias the trigger  28  outwardly to move the contact plate  30  away from the contacts  32 . 
         [0029]    A direction control switch  38  is provided in the housing  12  for controlling the direction of rotation of the motor  18 . As depicted, the direction control switch  38  is located above the trigger  28  and comprises a slide switch. In alternative embodiments, the direction control switch  38  may comprise any suitable type of switch and be provided in other suitable locations on the tool  10 . 
         [0030]    The counterpart contacts  32  associated with the contact plate  30  are provided on an elongated circuit board  36 , extending in the interior of the grip portion  16 , diametrically opposite the contact plate  32  and in its reciprocation region. The contacts  32  are electrically connected to a power circuit that is implemented on the circuit board  36 . When the contact plate  30  on the trigger contacts the counterpart contacts  32  on the circuit board  36 , the power circuit is closed and power is supplied from a power source, such as battery  40 , to the motor  18 . The circuit board  36  is arranged generally perpendicular to the center plane of the housing  12  so that the circuit board  36  can be clamped in groove-like recesses (not shown) provided in the half shells of the housing  12 . 
         [0031]    The battery  40  comprises a rechargeable battery that is secured within the pistol grip portion  16  of the housing  12 . The battery  40  is arranged generally parallel to the circuit board  36  and includes contact plates  42 ,  44  at each end of the battery  40  which serve as soldering lugs and are wired to the circuit board and electrically connected to the power circuit. In one embodiment, the rechargeable battery  40  comprises a lithium-ion cell battery although, in other embodiments, other types of rechargeable batteries, including Ni-Cad cell batteries, may be used. 
         [0032]    A charging circuit is implemented on the circuit board  36  that is electrically coupled to the battery  40 . The power tool  10  is provided with a charging port  46  which is wired to the circuit board  36  and electrically connected to the charging circuit. The charging port  46  is configured to receive a charging connector  48  ( FIG. 9 ) that is coupled to a power source (not shown), such as an AC outlet. When the charging connector  48  is received in the charging port  46  of the power tool, power from the power source is coupled to the charging circuit. In response to receiving power via the charging port  46 , the charging circuit delivers power to the battery  40  to charge the battery  40 . In the embodiment of  FIGS. 3-7 , the charging port  46  is located in the base of the grip portion  16  of the housing  12 . An opening  50  is formed in the grip portion  16  of the housing to provide access to the charging port  46 . In alternative embodiments, the charging portion  46  may be provided in other locations on the housing  12 . 
         [0033]    As discussed above, the charging circuit is configured to utilize a USB power source to charge the rechargeable battery. Referring to  FIGS. 8 and 9 , in one embodiment, the charging port  46  of the power tool comprises a standard Micro-USB port configured to receive a standard Micro-USB connector  48 . The Micro-USB connector  48  is attached at an end of a USB cable  52  that is electrically coupled to a USB power source (not shown) at the other end of the cable. As discussed above, the cable may include an AC adapter and plug at the other end that enables the USB power to be derived from a conventional AC outlet. Alternatively, the cable may include a second USB connector that is connected to a USB port of a computer, laptop, or other device that is capable of providing USB power including an AC adapter and plug that is provided with a USB port. 
         [0034]    While the disclosure has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications and further applications that come within the spirit of the disclosure are desired to be protected.