Patent Application
20180056496
This invention relates generally to the field of handheld power tools, and more particularly to handheld power tools having rechargeable lithium-ion batteries.
Handheld power tools may be configured as corded tools which receive power via a cord which connects to a power source, such as an AC outlet. While the power cord provides a reliable source of power for the tool, the cord poses limits to the areas and operating range of the power tool. Cordless power tools are configured to receive power from a battery attached to the tool. Because the power source is part of the tool, cordless power tools provide portability and convenience advantages over corded tools.
Cordless power tools are typically provided with rechargeable batteries which can be recharged as needed when the batteries power has been depleted. One type of rechargeable battery which has achieved widespread use is lithium-ion based batteries. Lithium-ion cell batteries are typically lighter and have a much slower self-discharge rate than energy-equivalent batteries of other types. However, lithium-ion cell batteries can also be expensive. Lithium-ion cell batteries also require electronics for protecting the battery from being drained too much. The cost of the battery, charger and control electronics can cost more than 70% of the total cost of the power tool.
For the purposes of promoting an understanding of the principles of the invention, 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 invention is thereby intended. It is further understood that the present invention includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles of the invention as would normally occur to one of ordinary skill in the art to which this invention pertains.
The present disclosure is directed to a modular handheld power tool and power tool system that enables certain tool components, such as a mechanical drive system and power source, e.g., rechargeable battery, to be provided as a stand-alone device which can be equipped with different head units that can be coupled to the mechanical and/or electrical power of the base unit to perform different functions. Thus, the same battery and mechanical drive system can be used to power multiple tools. Because the same battery and mechanical drive system is used for multiple tools, the expense to a consumer of having multiple tools for performing different tasks can be significantly reduced.
In accordance with the present disclosure, a power tool is provided with a modular configuration in which the battery, charger, and power control system are provided as a separate unit, referred to herein as a base unit, to which different tool head units can be attached and swapped out as needed. The base unit provides the power to the head unit and also includes the battery monitoring and battery discharge control functionality that is required to maintain the battery, such as a rechargeable, lithium-ion battery, in good working order and to maximize the life of the battery.
The energy storage unit 20 comprises a rechargeable lithium-ion cell battery. The battery may be removable from the housing or integrated into the housing. The rechargeable battery is configured to produce an output voltage that is capable of powering the head unit, such as 3.6V, 7.2V, 9.6V, 12V, 14.4V, 18V, or 24V although any suitable battery voltage may be used.
A battery charging system 28 is configured to recharge the rechargeable battery 20. The battery charging system 28 is coupled to the rechargeable battery 20 to supply energy to the battery in order to recharge the battery. The charging system 28 may receive power from an external source via a charging connection 30. Any suitable type of connection may be used.
The power control system 18 is configured to control the supply of power from the battery 20 to the head unit and to monitor the voltage and/or current level of the rechargeable battery 20 to prevent over discharging and overheating of the battery. The power control system is configured to cut off the supply of power to the head unit when the battery voltage level reaches a predetermined minimum value and when the battery temperature reaches a predetermined maximum value. The power control system is also configured to control the discharge rate or current draw of the battery. The power control system may be configured to monitor and/or control any function of the battery that is needed to maintain the battery in good working condition.
The power control system supplies power to the head unit via an electrical power output connection 32. Any suitable type of connection may be used for the power output connection 32. The base unit also includes an operator control element 34, such as a pushbutton, slide switch, or the like, for controlling indicating when the operator desires for power to be supplied to the head unit.
The head unit 14 of the modular power tool 10 includes a housing 36 which encloses tool components which are configured to provide the functionality for the head unit. The housing 36 may be formed of a rigid material such as plastic, metal, or composite materials such as a fiber reinforced polymer, and has any suitable shape for enclosing and facilitating the functionality provided by the head unit.
The head unit 14 is configured to be quickly and easily installed and removed from the base unit 12 of the tool so that different head units that provide different tool functions can be swapped in and out as needed. In one embodiment, to enable the head unit 14 to be quickly installed and removed from the base unit 12, the head unit and the base unit are provided with mating attachment structures 38, 40 which enable the head unit 14 to be secured to the base unit 12 without the use of fasteners, such as screws or bolts. The attachment structures 38, 40 may be configured to provide a snap fit connection, twist lock connection, and the like. For example, the head unit may be provided with detents, slots, prongs, or the like which are configured to be interact with complementarily configured detents, slots, prongs, or the like provided on the base unit.
In the embodiment of
The head unit 14 includes a tool output component which is configured to receive mechanical or electrical power from the base unit to perform a tool function. The tool function can be any of a variety of different functions which may be implemented in a head unit, examples of which are included below. The head unit 14 of
The drive 54 may include a transmission (not shown) for converting the rotary motion of the input drive shaft 42 (as provided by the drive shaft of the base unit) to a suitable motion for driving the output shaft 48. For example, the transmission may include one or more gears, clutches, drive shafts, and the like (not shown) for altering the speed and/or torque provided by the drive system 54. The transmission may be configured to alter the drive axis so that it is transverse to the axis of rotation of the drive system. The transmission may also be configured to convert the rotary motion to another type of drive motion for the head unit, such as oscillating, orbiting, and/or reciprocating.
The head unit 14 is configured to utilize electrical power received from the base unit 12 to power electrical components, such as light 46. The electrical power from the base unit 12 may also be used to power sensors, control systems, and drive systems (not shown) which may be incorporated into the head unit to add, facilitate and/or enhance functionality of the head unit. The head unit 14 may also include operator control elements 56, such as buttons and switches, for controlling the electrical and/or mechanical components of the head unit.
The head unit 14b of the embodiment of
Referring to
Although not depicted in the drawings, various other types of head units may be implemented which perform a variety of other functions. For example, head units may be configured as vacuum head units which can attached to the base unit and powered to serve as a portable vacuum. A head unit may also be configured as a blower head unit which can be powered by the base unit to output an air flow which can be used for various tasks as needed. Substantially any type of head unit may be implemented which can receive mechanical and/or electrical power provided by the base unit to function.
The base unit 12 may also be used without an attached head unit. For example, the base unit 12 may be used to supply electrical energy to other components which need not be attached to the base unit. The electrical energy provided by the base unit 12 may be used to charge electrical components, such as a mobile phone or tablet 66, as depicted in
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.
