MXPA06009079A - Fan control for combustion-powered fastener-driving tool - Google Patents

Abstract

A combustion-powered fastener-driving tool (10) includes a combustion--powered power source (14), at least one fan (48) for associated with the power source (14), at least one temperature sensing device (60) in operational proximity to the power source (14) and a control system (67) operationally associated with the power source (14) and connected to the at least one fan (48) and at least one temperature sensing device (60) for adjusting the length of timefor energizing the at least one cooling fan (48) as a function of power source temperature sensed by the at least one temperature sensing device (60).

Description

FAN CONTROL FOR FUEL DRIVER DRIVE TOOL DRIVER FOR COMBUSTION RELATED REQUEST The present application calls for priority in accordance with 35 U SC § 1 20 from US Serial No. 60 / 543,053 filed on February 9, 2004.

BACKGROUND The present invention relates generally to fastener driving tools used to drive fasteners within the workforce, and specifically to a fastener drive tools powered by combustion, also referred to as combustion tools. The combustion-powered tools are known in the art.

Illustrative 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 for Nikolich United States Patent No. Ref. No. 32,452, and Patents of the United States of North America 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. Said tools incorporate a tool housing, generally in the form of a gun, enclosing a small internal combustion engine. The engine is powered by a metal container of pressurized fuel gas, known a fuel cell. A battery-powered electronic power distribution unit produces a spark for firing, and a fan located in a combustion chamber provides efficient combustion within the moon chamber, while facilitating auxiliary processes for the combustion operation of the device. Such auxiliary processes include: introducing the fuel into the combustion chamber; mix the fuel and the air inside the camera; and removing, or debugging, combustion byproducts. The motor includes an alternating piston with a rigid, elongated drive blade positioned within a single cylinder body. A valve sleeve is axially reciprocable around the cylinder and, through a link, moves to approach the combustion chamber when a working contact element at the end of the link is pressed against a workpiece. The action of pressure also activates a fuel metering valve to introduce a specified volume of fuel into the closed combustion chamber. By pulling a trigger, which causes the spark to ignite a gas charge in the combustion chamber of the engine, the combined piston and the drive blade are forced down to fire a fastener in place and propel it into the workpiece. The piston then returns to its original position, or pre-firing, through differential gas pressures inside the cylinder. The fasteners are fed into the feeder reservoir style within the nozzle, where they are held in a properly positioned orientation to receive the impact of the driving blade. The combustion tools identified above incorporate a fan in the combustion chamber. This fan performs many functions, one of which is cooling. The fan performs cooling by extracting air through a tool between firing cycles. This fan is powered by the power supplied by an internal battery and to prolong the life of the battery, it is a common practice to minimize the motor's operating time. Also, the reduced operating time of the fan reduces the wear of the fan motor (bearings and brushes), limits the emission of sound from a tool due to air flow, and more importantly limits the infiltration of dirt into a tool . To operate the fan 'on time', combustion tools incorporate in a common way a control program that limits the fan 'in time' to 10 seconds or less. Combustion tool applications that demand high cycle speeds or require a tool to operate at elevated ambient temperatures often cause the temperature of the tool component to rise. This leads to a number of performance issues. The most common is an overheated condition that is evidenced by the firing of a tool but without a fastener impulse. This is often referred to as a "jump" or "blank shot". As described previously, the vacuum return function of a piston depends on the cooling rate of the residual combustion gases. As the component temperatures increase, the differential temperature between the combustion gas and the engine walls is reduced. This increases the duration of the piston return cycle to such an extent that the user can open the combustion chamber before the piston has returned, even with a closing mechanism installed. The result is that the driving blade remains in the nozzle of a tool and prevents the advancement of the fasteners. Consequently, a subsequent firing event of a tool does not drive a fastener. Another disadvantage of the high operating temperature of a tool is that there are stresses related to the heat on the components of a tool. Among other things, the life of the battery is reduced and it has been found that the internal lubricating oil has a reduced lubrication capacity with prolonged operation of a tool at high temperature. Therefore, there is a need for a comb driver powered by combustion that reduces the fan in time. Further, there is a need for a combustion-powered fastener tool that handles tool operating temperatures within accepted limits in order to prolong the performance and maintain a relatively fast piston return to the pre-firing position.

BRIEF DESCRIPTION OF THE INVENTION Necessities m onsed m ons covered or exceeded by this combustion-powered fastener tool which overcomes the limitations of current technology. The present tool is provided with a temperature sensing system that more effectively controls the operating time of the fan. The operating time of the fan can be determined by monitoring the temperature of a tool, by comparing the temperature of the energy source against the ambient temperature, or by controlling the operating time of the fan as a function of the speed of a tool. More specifically, a deflocking tool to be supplied by combustion includes a power source powered by combustion, at least one fan associated with the power source, at least one temperature sensing device in proximity to the source operating of energy, and a control system operatively associated with the power source and connected to said at least one fan and said at least one temperature sensing device for adjusting the operating time length of at least one fan as a function of the energy source temperature detected by said at least one temperature sensing device. In another modality, one. The combustion-driven fastener driving tool includes a power source powered by combustion, at least one fan associated with the power source during the operation, and a control system operatively associated with the power source and connected to said at least one a fan to adjust the length of operation time of the fan as a function of a burning rate of the power source.

BRIEF DESCRIPTION OF THE DIFFERENT VIEWS OF THE DRAWINGS FIGURE 1 is a front perspective view of a fastener driving tool incorporating the present temperature control system; FIGURE 2 is a fragmentary vertical cross section of a tool of FIGURE 1 shown in the rest position; FIGURE 3 is a fragmentary vertical cross section of a tool of FIGURE 2 shown in the pre-trigger position; FIGURES 4A-C are an operational flow diagram illustrating a control program wherein a tool temperature is monitored for fan energization when necessary; and FIGURE 4D is a flowchart or process diagram that illustrates a control program where the triggering speed of a tool is monitored for fan energization.

DETAILED DESCRIPTION Referring now to FIGURES 1-3, a combustion-powered fastener driving tool incorporating the present control system is generally designated 10 and is preferably of the general type described in detail in the patents listed above and incorporated by reference to the present application. A housing 12 of a tool 10 encloses a self-contained internal power source 14 (FIGURE 2) within a main housing chamber 16. As in conventional combustion tools, the power source 14 is powered by internal combustion. It includes a combustion chamber that is connected to a cylinder 20. A piston 22 placed alternately inside the cylinder 20 is connected to the upper end of a driving blade 24. As shown in FIGURE 2, an upper limit of the reciprocating displacement of the piston 22 is referred to as an upper counterpoint or pre-firing position, which occurs just before firing, or ignition of the combustion gases that initiates the downward pulse of the driving blade 24 to impact a fastener (not shown) to push it into a work piece. Through the squeezing of a trigger 26 associated with a trigger switch 27 (shown in shading), an operator induces combustion within the combustion chamber 18, causing the driving blade 24 to be driven forcefully downward through a nozzle 28 (FIGURE 1). The nozzle 28 guides the driver blade 24 to impact a fastener that has been supplied into the nozzle through a fastener feeder 30. Included in the nozzle 28 is a work piece contact element 32, which is connected, through a link 34 to an alternating valve sleeve 36, an upper end of which partially defines the combustion chamber 18. The depression of a tool housing 12 against the workpiece contact element 32 in a downward direction as seen in FIGURE 1 (other operational orientations are considered as known in the art), causes the workpiece contact element to move from a rest position to a pre-trip position. This movement exceeds the orientation normally biased downward of the workpiece contact element 32 caused by a spring 38 (shown in shading in FIGURE 1). Other locations for the spring 38 are considered. Through the link 34, the workpiece contact element 32 is connected to and alternately moves with the valve sleeve 36. In the rest position (FIGURE 2), the combustion chamber 18 is not sealed, since there is a null space 40 which includes an upper space 40U separating the valve sleeve 36 and a cylinder head 42, which accommodates a chamber switch 44 and a spark plug 46, and a lower space 40L separating the valve sleeve 36 and the cylinder 20. In the preferred embodiment of the present tool 10, the cylinder head 42 is also the mounting point for at least one cooling fan 48 and the associated fan motor 49 which extends into the combustion chamber 18 as is known in the art and is described in the patents that have been incorporated by reference above. In addition, U.S. Patent No. 5,713,313 also incorporated by reference, discloses the use of multiple cooling fans in a combustion powered tool. In the rest position illustrated in FIGURE 2, a tool 10 is disabled from firing because the combustion chamber 18 is not sealed at the top with the cylinder head 42 and the chamber switch 44 is open. Triggering is enabled when an operator presses the work piece contact element 32 against a work piece. This activation overcomes the force of deflection of the spring 38, causes the valve sleeve 36 to move upwards relative to the housing 12, closing the space 40, sealing the combustion chamber 18 and activating the chamber switch 44. This operation induces also that a metered amount of fuel be released into the combustion chamber 18 from a fuel container 50 (shown in fragment). In an operating mode known as sequential operation, upon pulling the trigger 26, the spark plug 46 is energized, igniting the fuel and air mixture in the combustion chamber 18 and sending the piston 22 and the driving blade 24 downward in the direction to the bra waiting to enter inside the work piece. As the piston 22 moves down the cylinder 20, it pushes a flow of air that is discharged through at least one petal, lamellae or regulator valve 52 and at least one vent hole 53 located beyond of the displacement of the piston (FIGURE 2). At the bottom of the piston stroke or the maximum piston displacement distance, the piston 22 impacts a resilient shock absorber 54 as is known in the art. With the piston 22 beyond the discharge regulating valve 52, the high pressure gases are discharged from the cylinder 20. Due to the internal pressure differentials in the cylinder 20, the piston 22 is withdrawn towards the pre-firing position shown in FIGURE 3. As described above, one of the problems confronting the designers of combustion-powered tools of this type is the need for a rapid return of the piston 22 to the pre-trigger position before the next cycle. This need is especially critical if a tool is to be triggered in a repetitive cycle mode, where a firing occurs each time the workpiece contact member 32 is retracted, and during which time the trigger 26 is continuously maintained. in the traction or depressed position. During the repetitive cycle operation, the ignition of a tool is activated on the chamber switch 44 which is closed as the valve sleeve 36 reaches its highest position (FIGURE 3). Said repetitive cycle operation often leads to high tool operating temperatures, which extends the piston return time. To handle these cases where extended tool cycling and / or high ambient temperatures induce high tool temperature, at least one temperature sensing device 60 such as a thermistor (shown in shading in FIG. 1) is positioned Preferably at a lower end of the cylinder 20 and is preferably positioned to be in or in operative relation with, a forced convection flow stream from tool 1 0. Other types of temperature sensing device are considered. Likewise, other locations in a tool 10 are considered depending on the application. The temperature sensing device 60 is connected to a control program 66 associated with a central processing unit (CPU) 67 (shown in shading in FIGURE 1) and is configured to extend the function 'in time' of said at least a cooling fan 48 until the temperature is lowered to the preferred "normal" operating range.Alternatively, the program 66 is configured to maintain the fan 48 for a fixed time, for example 90 seconds, which is long enough to ensure that the temperature of the combustion chamber has returned to the "normal" operating range In the preferred embodiment, the program 66 and the CPU 67 are located in a handle portion 68 of a tool 10. The temperature threshold is selected based on the proximity of the temperature sensing device 60 to the components of the power source 14, the forced convection flow stream, and the effects of cooling desired to avoid the annoying operation of the fan. Excessive operating time of the fan unnecessarily removes contaminants within a tool 10 and depletes battery power. Other disadvantages of excessive fan operating time include premature fan component failure and lower fan-induced operational noise from a tool 10. For applications that de high cycle speed and / or when high ambient temperatures present overheating problems, forced convection controlled by temperature will produce a more reliable perfore of combustion-driven nail and will also reduce thermal stress on a tool. Referring now to FIGURE 4A and considering a sequential firing mode, although the present program can also be applied to a repetitive firing mode, a portion of the control program 66 associated with the tool temperature monitoring is designated as 70. Starting at the START indicator 71, program 70 determines at 72 whether the camera switch 44 (designated HEAD) is open or not. A closed HEAD means that the combustion chamber 18 is closed and ready for combustion. If the HEAD is closed, the program cycles. If the HEAD is open, the program 70 checks if the trigger 26 is open at 74. If the trigger 26 is closed with the HEAD open, the program cycles. In step 76, once the HEAD is closed, the fan 48 is turned on in step 78, which circulates the mixed fuel and air in the combustion chamber 18. Next, the program 70 checks whether it is activated or not the firing process when determining whether trigger 26 is closed at 80 or HEAD is open at 82. If trigger 26 has not been closed, and HEAD 44 reopened, as if the operator was interrupted in the use of a tool 10 or decided to leave it unused, program 70 checks at 84 if the 90 second fan signal is on or not. if not, this indicates that a tool has not been used, and the fan 48 is turned on at 86 for 5 seconds, and then off. If the 90-second fan signal has been turned on, program 70 returns to START at 71, and the extended cooling cycle continues. Returning to the closed trigger cycle 80-open HEAD 82, once the trigger 26 closes, indicating that combustion is desired, the program 70 activates a spark at 90, which can also be executed in conjunction with the control circuit 66 After turning on, the program 70 determines whether or not HEAD 44 is open at 92, and if not, the program cycles. If HEAD 44 is open, program 70 checks to see if trigger 26 is open at 94. If not, program 70 cycles until the trigger opens, at which time the program goes to TEMP at 96, or COMPARE TEMP in 98, or RATE in 100, depending on which of the present modalities is used. The TEMP 96 subroutine uses a temperature sensor 60 to monitor the tool temperature and turn on the fan 48 in the extended operation, also known as "overdrive" when the tool temperature exceeds a pre-set value. The COMPARE TEMP 98 subroutine uses a value calculated based on the readings of two temperature sensors to activate the fan 48 in overdrive, and the RATE subroutine 100 monitors the firing speed of a tool 10 to activate the fan overdrive. Referring now to FIGURE 4B, the TEMP 96 subroutine first determines whether the HEAD 44 is open at 102. Once it is determined that the HEAD 44 will be opened, the trigger 26 is verified at 104. If the trigger 26 is closed, indicating that the operator is actively using a tool, program 70 cycles until the trigger is open. At that time, in step 106, the program 70 monitors the temperature from the temperature sensor 60. In step 108, the program 70 determines whether the detected temperature is greater than 60 ° C. If the temperature is not greater than 60 ° C, at 108, the program 70 determines whether the 90-second fan synchronizer has been activated at 110, which would also indicate that the fan 48 has been energized for that period. Otherwise, indicating that a tool 10 has not been used extensively or the use has been discontinued, the fan 48 is turned on for 5 seconds at 112 and then turned off, after which the program 70 returns to the START routine. 71. If the temperature is greater than 60 ° C at 108 and the 90-second fan synchronizer, as well as the fan 48, have been turned on at 110, then the temperature detector 60 is checked at 114 to determine if the temperature monitored is less than or equal to 40 ° C. Otherwise, indicating that a tool is still at operating temperature, program 70 starts the routine START 71. If the detected temperature of the tool has been reduced to less than or equal to 40 ° C after the operation of the fan synchronizer of 90 seconds and the fan 48, even if 90 seconds have not elapsed, the 90-second synchronizer inverts a 5-second fan synchronizer, which is turned on at 116. After 5 seconds, the fan 48, and an optional indicator, like a light and / or audible alarm 115 (FIGURE 1) that has been turned on in conjunction with the energization of the 90 second fan synchronizer (described below at 118) is turned off. Next, program 70 goes to START at 71. If the monitored tool temperature is greater than or equal to 60 ° C to 108, then the fan 48, the fan synchronizer, as well as the optional 115 inciter are turned on for 90 seconds at 118, then they are turned off, after which the program 70 goes to START at 71. It is preferred that the fan operating for 90 seconds is sufficient to cool a tool 10 during the operation and to avoid overheating. However, it will be understood the temperature levels and the operating time of the fans described herein may be modified to suit the particular application. Referring now to FIGURE 4C, the subroutine is provided COMPARE TEMP 98. In this embodiment, a tool 10 is provided with a first temperature sensor 60 near the power source 14, such as the cylinder 20 or the combustion chamber 18. A second temperature sensor 120 (shown in shading) in FIGURE 1) it is also located in a tool 10, although remote from the power source 14 so that it is not significantly affected by the power source 14. A potential location is on a tool housing 12 in the portion of mango 68, although other locations are considered.

Initially, in step 124, the program 70 determines the reference value of ambient temperature, or close to the ambient, from the reading of the second temperature detector 120. Next, in step 126, the program 70 determines a temperature of reference tool from the first temperature detector 60 located closer to the power source 14. In step 128, the readings from the detectors 120 and 60 are compared, obtaining an AT value. In step 130, the resulting difference AT is compared against a predetermined value, such as a conventional look-up table developed to suit the application. If the resulting difference is greater than the predetermined value, then in step 132 the fan 48 is turned on for 90 seconds, then turned off. If the resulting difference is less than the predetermined value, then in step 134 the fan 48 is turned on for 5 seconds, after turning off. It is also considered that the subroutine 98 is configurable so that the greater the difference between AT, the longer the operation time of the fan. At the conclusion of any fan activation, the program returns to START at 71. It is also considered that the AT can be compared with the ambient reference temperature to determine the operating time of the fan. Referring now to FIGURE 4D, the RATE 100 subroutine is described.

A tool cycle speed, or the number of shots per minute, or the number of combustions or ignitions of the spark plug 46 during the time, is determined by the program 70 in step 136, and after that value is compared against a predetermined speed in step 138 as in a search table. This data is preferably monitored by the CPU 67. Depending on the application, a threshold trigger rate is established and added to the program 70 which is considered sufficient to cause an excessive tool temperature, for example 60 ° C. E I p rogram 70 verifies e ntonces in I cap 1 40 to determine whether the tripping speed exceeds the predetermined speed, and if so, a tool 10 is probably overheating or has a high operating temperature. As such, in step 142, the fan is turned on for 90 seconds, then turned off. If a tool 10 is equipped in that manner, the indicator 115 is energized temporarily, as described above in relation to FIGURE 4B. If the calculated trigger speed is lower than the predetermined speed, indicating that the tool temperature is acceptable, the fan 48 is turned on for 5 seconds in step 144, then switched off, again optionally with periodic energization of indicator 115. Upon execution of any of steps 142 or 144, program 70 returns to the beginning at 71. Note that it is considered that the program 70 can be configured so that GO TO T EMP 96, GO TO COMPARE T EMP 98 and GO TO RATE 1 00 can be used in combination with each other, and it is not required to be used exclusively as a control of fan. While a particular embodiment of the present temperature monitoring for fan control of comb driver powered by combustion has been described herein, those skilled in the art will appreciate that changes and modifications can be made thereto without departing from the invention. in its broader aspects and as established in the following claims.

Claims (22)

CLAIMS:

1. A comb driver powered by combustion, characterized in that it comprises: a source of energy powered by combustion; at least one fan associated with said power source; at least one temperature sensing device in close proximity operative to said power source; and a control system operatively associated with the power source and connected to said at least one fan and said at least one temperature sensing device for adjusting the length of time to energize said at least one fan as a function of temperature of the energy source detected by said at least one temperature sensing device.

2. A tool according to claim 1, further characterized in that the control system is configured to energize said at least one fan until said temperature detecting device detects a predesignated acceptable temperature of said power source.

3. A tool according to claim 1, further characterized in that the control system is configured to energize said at least one fan for a fixed period.

4. A tool according to claim 1, further characterized in that said at least one temperature sensing device is placed in a forced convection flow stream of said tool.

5. A tool according to claim 1, further characterized in that said temperature sensing device includes at least one thermistor.

6. A tool according to claim 5, further characterized in that said at least one thermistor is preferably located in close operating proximity to the power source.

A tool according to claim 1, further characterized in that said at least one temperature sensing device includes a temperature sensing device located near the power source, and a second temperature sensing device remotely located on the tool from the power source, and said control system is configured to compare the first and second temperature sensing devices, and to adjust the length of time to energize said at least one fan as a function of said comparison.

8. A tool according to claim 7, further characterized in that said second temperature sensing device measures the ambient temperature.

9. A tool according to claim 7, further characterized in that said control system is configured to calculate an AT using said first and second temperature sensing devices and adjusting the length of time to energize said at least one fan as a function of said AT.

A tool according to claim 9, further characterized in that said control system is configured to relate said AT and said second temperature sensing device to adjust the length of time to energize said at least fan.

11. A tool according to claim 9, further characterized in that the control system is configured such that the fan is energized for a period that increases in proportion to the AT.

12. A tool according to claim 1, further characterized in that said tool includes a trigger switch and a head switch, any of which is configured to initiate combustion and as such indicate the active operation of said tool, and said Control system is configured to determine if the tool is in active operation, and if so, to monitor the temperature of said tool and to determine if the temperature of the tool exceeds a predetermined value, and if so, energize said at less a fan.

13. A tool according to claim 12, further characterized in that said at least one fan is de-energized after a predetermined amount of time and when the monitored tool temperature drops below a predetermined value.

A tool according to claim 13, further characterized in that said at least one fan is energized if the monitored temperature of the tool exceeds 60 ° C, said at least one fan is energized for 90 seconds, or until the Monitored tool temperature is equal to or less than 40 ° C.

15. A tool according to claim 1, further characterized in that the control system is also configured to energize said at least one fan as a function of firing speed of a tool.

16. A comb driver powered by combustion, characterized in that it comprises: a source of energy fed by combustion; at least one fan associated with the power source during the operation; and a control system operatively associated with the power source and connected to said at least one fan for adjusting the length of time to energize said at least one fan as a function of the number of combustion ignitions of said power source.

A tool according to claim 16, characterized in that it further includes at least one temperature sensing device, and wherein the control system is configured to monitor the rate of combustion ignitions and to energize said at least one fan when said ignition speed exceeds a predetermined amount, said temperature detecting device determines the amount of time that said at least one fan is energized.

18. A tool according to claim 17, further characterized in that the energizing time of said at least one fan is proportional to the firing rate of said tool.

19. A method of operation of a combustion-powered tool, having a combustion chamber and at least one fan located in operative relation with the combustion chamber, the method characterized in that it comprises: determining whether a tool is operative; monitor a tool temperature to determine that a tool is operational; and energizing at least one fan for a predetermined amount of time if a tool temperature exceeds a predetermined value.

The method according to claim 19, characterized in that it further includes the step of de-energizing said at least one fan if the predetermined amount of time has not elapsed and a tool temperature falls below a predetermined lower value.

The method according to claim 19, further characterized in that the predetermined value is approximately 60 ° C and the predetermined amount of time for fan energization is approximately 90 seconds.

22. The method according to claim 19, further characterized in that said predetermined lower value is about 40 ° C.