WO2008060281A1

WO2008060281A1 - Power source conversion and software lockout for corded power nailer

Info

Publication number: WO2008060281A1
Application number: PCT/US2006/044520
Authority: WO
Inventors: William J. Heinzen; Tomoo Dohi
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 2006-11-17
Filing date: 2006-11-17
Publication date: 2008-05-22
Anticipated expiration: 2009-05-17
Also published as: TW200848224A; JP5080588B2; JP2010510076A

Abstract

A combustion-powered fastener-driving tool is provided, including a housing enclosing a combustion-powered power source and defining a battery socket dimensioned for slidably receiving a battery, a control system connected to the battery socket and including a control program, the system and the program powered through the socket. A transformer is provided which is connectable to line power and configured for physical and electrical engagement in the socket for powering the tool.

Description

POWER SOURCE CONVERSION AND SOFTWARE LOCKOUT FOR

CORDED POWER NAILER

TECHNICAL FIELD

The present invention relates generally to fastener-driving tools used to drive fasteners into workpieces, and specifically to combustion-powered fastener-driving tools, also referred to as combustion tools or combustion nailers. The invention is specifically directed towards combustion nailers designed for corded operation.

BACKGROUND ART

Combustion-powered tools are known in the art. Representative tools are manufactured by Illinois Tool Works, Inc. of Glenview, Illinois for use in driving fasteners into workpieces, and are described in commonly assigned patents to Nikolich U.S. Pat. Re. No. 32,452, and U.S. Pat. Nos. 4,522,162; 4,483,473; 4,483,474; 4,403,722; 5,133,329; 5,197,646; 5,263,439 and 6,145,724 all of which are incorporated by reference herein.

Such tools incorporate a tool housing enclosing a small internal combustion engine or power source. The engine is powered by a canister of pressurized fuel gas, also called a fuel cell. An electrically powered distribution unit produces a spark for ignition, and a fan located in a combustion chamber provides for both an efficient combustion within the chamber, while facilitating processes ancillary to the combustion operation of the device. Such ancillary processes include: mixing the fuel and air within the chamber; turbulence to increase the combustion process; scavenging combustion by-products with fresh air; and cooling the engine. The engine includes a reciprocating piston with an elongated, rigid driver blade disposed within a cylinder body.

A valve sleeve is axially reciprocable about the cylinder and, through a linkage, moves to close the combustion chamber when a work contact element at the end of the linkage is pressed against a workpiece. This pressing action also triggers a fuel-metering valve to introduce a specified volume of fuel into the closed combustion chamber.

Upon the pulling of a trigger switch, which causes the spark to ignite a charge of gas in the combustion chamber of the engine, the combined piston and driver blade is forced downward to impact a positioned fastener and drive it into the workpiece. The piston then returns to its original or pre-firing position, through differential gas pressures within the cylinder. Fasteners are fed magazine-style into the nosepiece, where they are held in a properly positioned orientation for receiving the impact of the driver blade. Upon ignition of the combustible fuel/air mixture, the combustion in the chamber causes the acceleration of the piston/driver blade assembly and the penetration of the fastener into the workpiece if the fastener is present.

Such tools are typically powered by a rechargeable battery to enhance portability. Among other optional functions, the battery powers the ignition system, the ventilating fan as well as operational software. While battery power provides the freedom of portability, it also requires recharging, which can cause tool downtime if the operator lacks replacement recharged batteries, or a charger is missing or inoperative. Thus, in some cases, to avoid these inconveniences, and/or when the use of a power cord is considered acceptable, there is a desire to operate from conventional electrical power provided through, and referred to as wall sockets, line power or the like.

DISCLOSURE OF INVENTION

The above-listed needs are met or exceeded by the present combustion-powered fastener-driving tool which overcomes the limitations of the current technology. To enable the tool to operate easily from line voltage from a wall socket, a transformer is provided in the form of a battery so that it easily fits within the standard battery socket provided in such tools. Thus, the transformer connects to the tool control system through the battery contacts in the same manner as a standard battery. The control system is configured to discriminate between battery supplied power and line voltage provided through a transformer. To prevent the tool from being used with a standard battery, the control system is preferably designed to operate at a voltage beyond the range of a charged battery.

More specifically, a combustion-powered fastener-driving tool is provided, including a housing enclosing a combustion-powered power source and defining a battery socket dimensioned for slidably receiving a battery, a control system connected to the battery socket and including a control program. The system and the program are powered through the socket. A transformer is provided which is connectable to line power and configured for physical and electrical engagement in the socket for powering the tool.

In another embodiment, a combustion-powered fastener- driving tool is provided, including a housing enclosing a combustion- powered power source and defining a battery socket dimensioned for slidably receiving a battery. A control system is connected to the battery socket and includes a control program, the system and the program powered through the socket, the control system configured for being inoperable upon insertion of a battery in the socket.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side elevation of a combustion nailer incorporating the present power conversion and software lockout system;

FIG. 2 is a rear elevation of the tool of FIG. 1;

FIG. 3 is a side elevation of the transformer used in the present combustion nailer;

FIG. 4 is an overhead plan view of the transformer of FIG. 3; and FIG. 5 is a graph representing a comparison of voltage over time between battery powered and line voltage powered combustion nailers. BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to FIGs. 1 and 2, a combustion-powered fastener-driving tool or combustion nailer incorporating the present invention is generally designated 10 and preferably is of the general type described in detail in the patents listed above and incorporated by reference in the present application. A housing 12 of the tool 10 encloses a self-contained internal power source 14 (shown hidden) as is known in the art. Included on the housing 12 is a handle 16 with a trigger 18. A fuel cell chamber 20 having a fuel cell door 22 encloses a fuel cell (not shown) which provides pressurized fuel for combustion.

Preferably located within the handle 16, but potentially located elsewhere within the housing 12 is a control system 24 (shown hidden) including a central processing unit CPU having a control program 26. As is known in the art, the CPU is a microprocessor, wired circuit or equivalent, and the control program 26 controls the operation of the tool 10, including fuel delivery if electronic fuel injection is provided, fan rotation when a fan is located within the combustion chamber, and ignition, among other things.

In a typical combustion nailer, a rechargeable battery powers the control program 26 and the control system 24, and is releasably held within a battery socket 28 located on a side of the housing 12. The socket 28 is configured for slidably accommodating the battery (not shown) so that contacts of the battery electrically engage socket contacts 30 (shown hidden). It is typical for the battery to be releasably engageable in the socket 28 both for recharging purposes and also for ensuring the tool 10 is inoperable for clearing fastener jams or other repairs. A latch 32 is typically provided for holding the battery in place during tool operation.

Other features of the tool 10 are a workpiece contact element 34 which contacts a workpiece prior to the driving of a fastener, the workpiece contact element constructed to slide relative to a nosepiece 36, and having a depth adjustment mechanism 38 for adjusting the relative spacing of the workpiece contact element 34 to the nosepiece for adjusting the depth of fastener insertion by the tool 10. A hook 40 is optionally provided to the handle 16 for suspending the tool 10 from a wall, rafter, ladder or user's belt when not in use. Opposite the battery socket 28 is a fastener magazine 42 for storing a supply of fasteners (not shown).

Referring now to FIGs. 1-4, an important feature of the present tool 10 is that it is designed for being powered by line voltage from a wall socket or generator rather than rechargeable batteries. To facilitate conversion from battery to line power, the tool 10 is provided with a transformer 44 having a power cord 46 (shown fragmentarily) connectable to line power and configured for physical and electrical engagement in the socket 28 for powering the tool. Preferably the transformer 44 has a similar shape to the battery so that it snugly yet releasably fits within the battery socket 28. However, it is contemplated that the transformer 44 can be provided in other shapes, as long as it makes positive electrical contact, engagement or interface with the battery socket 28. Further, the transformer 44 is provided with a similar, preferably biased, hook-like latch formation 48 for engaging the latch 32 of the battery socket 28. Opposite the power cord 46, the transformer 44 is provided with at least one and preferably a pair of contacts 50 which electrically engage the socket contacts 30 for powering the control system 24. When a user needs to disconnect the tool 10 from the source power, such as to clear tool jams or perform maintenance, the latch formation 48 is disengaged from the latch 32 and the transformer 44 is removed from the battery socket 28. It is preferred that the transformer 44 include polarity indicia 52 to facilitate correct installation by the user. Also, the power cord 44 is optionally provided with a strain relief formation 54 as is known in the art.

Another feature of the present tool 10 is that the control system 24 is configured for distinguishing or discriminating between the battery and the transformer 44. This feature is desired in applications where line voltage is the exclusive power source of the tool 10. It is known that such tools 10 are designed so that the battery has a specified fully charged voltage, which may vary with the tool or application, but in the present embodiment is approximately 7.2 Volts. As the battery becomes discharged, the tool will operate until the battery reaches a specified state of discharge, for example 4 Volts. Thus, the battery has an operational voltage range of between 7.2 and 4 Volts.

The referred to discrimination occurs because the control system 24 is configured to operate at a voltage outside the battery voltage range. More specifically, the transformer 44 is provided and is regulated to have a transformer voltage range above that of the battery voltage range. For example, the control system 24 is operable in a range of 8.0 + 0.2 Volts, and as such is operable at a minimum of 7.8 Volts, which is still below the voltage where internal components of the tool 10 are subject to damage. Also, the control program 26 is configured so that a cutoff voltage CV is established between the maximum of the battery pack (currently 7.2 Volts) and the minimum of the transformer 44 (7.8 Volts), below which the system 24 is inoperable. In the preferred embodiment, CV is 7.7 Volts; however it is contemplated that the various target voltages referred to above may change to suit the particular application, tool or local line voltage requirements.

Referring now to FIG. 5, it will be seen that the battery has a range of voltage BV which decreases over time with tool use. However, the transformer 44 has a constant voltage value TV such as 7.8 Volts, which is constant due to the connection to line voltage. A fully charged voltage FV is indicated, and is the maximum power of the battery. In the present tool 10, the control system 24 is configured for operation at the minimum CV voltage which is above a voltage level above that at which the battery is fully charged. The control program 26 is configured so that the system 24 will be inoperable at lower voltages. This configuration prevents operation of the tool 10 by battery power. The tool 10 is provided with software programming to the control program 26 to designate the desired operational voltage which corresponds to CV and TV. Such software programming is well within the skill of ordinary practitioners in the tool design art.

In the event a user inadvertently inserts a battery into the socket 28 instead of the transformer 44, the lower operational voltage of the battery will be below the minimum CV voltage. As such, the tool 10 will be inoperable.

While a particular embodiment of the present power source conversion and software lockout for a corded power nailer has been described herein, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects and as set forth in the following claims.

Claims

CLAIMS:

1. A combustion-powered fastener-driving tool, comprising: a housing enclosing a combustion-powered power source and defining a battery socket dimensioned for slidably receiving a battery; a control system connected to said battery socket and including a control program; said system and said program powered through said socket; and a transformer connectable to line power and configured for physical and electrical engagement in said socket for powering said tool.

2. The tool of claim 1 wherein said control system is configured for being powered by said transformer, but not by the battery.

3. The tool of claim 1 wherein said control system is configured for distinguishing between the battery and said transformer.

4. The tool of claim 1 wherein the battery has a voltage range, and said control program is configured to operate at a voltage outside said voltage range.

5. The tool of claim 4 wherein said transformer is regulated to have a transformer voltage range above that of the battery voltage range.

6. The tool of claim 5 wherein said control system is inoperable at a voltage between the battery voltage range and said transformer voltage range.

7. The tool of claim 4 wherein said transformer operates at a minimum of 7.8 volts.

8. The tool of claim 7 wherein said control system is inoperable below 7.7 volts.

9. The tool of claim 1 wherein said transformer is slidably removable from said socket for disconnecting said tool from electrical power.

10. The tool of claim 1 wherein said transformer is provided in a shape approximating that of the battery.

11. A combustion-powered fastener-driving tool, comprising: a housing enclosing a combustion-powered power source and defining a battery socket dimensioned for slidably receiving a battery; a control system connected to said battery socket and including a control program; said system and said program powered through said socket, said control system configured for being inoperable upon insertion of a battery in said socket.

12. The tool of claim 11 wherein said control system is configured for operating at a voltage threshold outside an operating range of said battery.

13. The tool of claim 11 further including a transformer powered by line voltage and configured for operational insertion into said socket for powering said tool.

14. The tool of claim 13 wherein said control system is configured for accommodating a voltage of said transformer, which is outside an operational range of said battery.

15. The tool of claim 14, wherein said battery has an operational voltage maximum of 7.2 Volts, and said transformer has a minimum operational threshold of 7.8 Volts.