JP2004074295A - Combustion driving tool - Google Patents

Abstract

Kind Code: A1 A combustion type driving tool for burning a combustible gas in an enclosed space and moving a driver blade by a rise in pressure to drive a nail or the like. Provided is a driving tool capable of performing a "hit and fire" operation.
The ignition is performed when both a first switch (25) for detecting pressing of a tool body (20) and a second switch (12) operated by an operator are operated. The operation is performed when one of the two switches 12 operates.
In addition, a means for delaying ignition until fuel is sufficiently diffused from fuel supply, a means for not firing until ignition is completed after the ignition is completed, and an ignition can be performed again are provided. To work.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a combustion type driving tool, and more particularly, to controlling ignition timing for starting combustion.
[0002]
[Prior art]
The combustion type driving tools are shown in Japanese Patent Publication No. 1-34753, Japanese Patent Publication No. 4-48589, Japanese Patent Publication No. 3-25307, Japanese Patent Publication No. 4-1337, Japanese Patent Publication No. 64-9149, and Japanese Patent Publication No. 3-25307.
[0003]
FIG. 4 shows an example of a conventional driving tool, and its mechanism and operation will be briefly described below. A head switch 25, which is a first switch that detects that the tool body 20 is pressed against the member 27 to be closed to form the closed combustion chamber 5, and a second switch that is operated by an operator to execute a driving operation. A certain trigger switch 12 is provided, and by pressing the tool body 20 against the member 27 to be fastened, the combustion chamber 5 is closed, and at the same time, the combustible gas, ie, fuel, in the gas cylinder 7 is injected into the combustion chamber 5, and then the head switch When 25 is turned on, the fan 6 in the combustion chamber 5 starts rotating.
[0004]
In this state, when the trigger switch 12 is depressed, the ignition circuit operates to cause spark discharge between the gaps of the ignition plugs 9 in the combustion chamber 5 to ignite the air-fuel mixture. The piston 10 in the cylinder 4 is driven by the explosion and expansion of the combustion gas, and the piston 10 descends. The driver blade 16 at the tip of the piston 10 attaches the nail or the like fed on the axis of the driver blade 16 to the member 27 to be fastened. Drive in.
[0005]
When the piston 10 descends to a predetermined position, the high-temperature and high-pressure combustion gas in the cylinder 4 is exhausted from the exhaust hole by a pressure difference from the atmospheric pressure above the combustion chamber 5 and the piston 10. When the air is exhausted to the atmospheric pressure, it is sealed by a check valve outside the exhaust hole below the cylinder 4. Even in this state, the temperature of the combustion chamber 5 is high, but this is agitated by the fan 6 and the like in the combustion chamber 5 and is cooled by transferring heat to the combustion chamber 5 and the inner peripheral surface of the cylinder 4. Then, due to the rapid cooling of the combustion gas, the closed space above the piston 10 has a negative pressure lower than the atmospheric pressure. On the other hand, since the lower surface of the piston 10 is open to the atmosphere, the piston 10 is pushed from below by the pressure difference and rises to return to the initial position. Further, when the tool body 20 is lifted from the member 27 to be fastened, the combustion chamber 5 is opened to the atmosphere, and the action of the fan 6 scavenges the combustion gas in the combustion chamber 5 and replaces it with fresh air. It returns to the state where it can be driven.
[0006]
As disclosed in U.S. Pat. No. 5,133,329, the ignition system includes a head switch 25 for detecting that the tool body 20 is pressed against the member 27 and a trigger switch 12 operated by an operator. When the trigger switch 12 is closed while the head switch 25 is open, ignition is possible, but when the trigger switch 12 is closed while the head switch 25 is open, ignition is not possible.
[0007]
These are so-called "single-hitting" operations in which the tool body 20 is pressed against the member to be fastened 27, and then the trigger switch 12 is pulled to drive a nail or the like, and then the trigger switch 12 is released to lift the tool body 20.
[0008]
[Problems to be solved by the invention]
However, in the above-mentioned "single-shot", each time one nail is driven, the finger must be separated, that is, the on / off operation of the trigger switch must be repeated, and the work speed is low, and the work efficiency is low due to fatigue of the worker. There was a problem. In the above-described configuration, there is a drawback that a so-called “hit-and-run” operation in which the tool body is continuously driven by intermittently pressing the tool body against the member to be fastened while the trigger switch is pulled cannot be performed.
[0009]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a combustion-type driving tool that eliminates the above-mentioned disadvantages of the prior art and enables a "single-hitting" operation and a "hit-and-run" operation.
[0010]
[Means for Solving the Problems]
In order to enable the above-mentioned "hitting" operation, a first switch for detecting pressing of the tool body against the member to be fastened and a second switch operated for embodying the intention of the operator to drive a nail or the like are provided. Regardless of the order in which they were closed, they were fired when they worked together. Further, the stirring means in the combustion chamber is operated when either the first switch or the second switch is operated.
[0011]
Further, a control means is provided for delaying the ignition from fuel supply until the fuel is sufficiently agitated and mixed, and for igniting and stopping the ignition until the driving is completed and the driving can be performed again, so that the "hitting" operation is reliably performed. I did it.
[0012]
Further, when the first and second switches are operated, the operator is notified by light, sound or vibration that the vehicle is in the ready state, and alerts the worker to prevent an accident due to carelessness. In the case of light, by providing it at two or more locations, the display light can be viewed regardless of the state of the tool body.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an embodiment of the ignition system. It comprises an ignition circuit 100, a control circuit 200, a fan control circuit 300, a trigger switch 12 as a second switch, a head switch 25 as a first switch, and the like. The ignition circuit 100 includes a battery 101, a first-stage booster circuit 110, a capacitor 115, a thyristor 114, and a high-voltage transformer 116. The first-stage booster circuit 110 accumulates charges in the capacitor 115 by switching the switching transistor 105 by the oscillation circuit 102, boosting the voltage by the boost transformer 106, and rectifying by the diodes 107 and 108. When the electric charge accumulates in the capacitor 115, the thyristor 114 is turned on to rapidly discharge the electric charge in the capacitor 115, the voltage is boosted through the high-voltage transformer 116, and discharge occurs between the discharge electrodes 117 of the ignition plug in the combustion chamber. Ignite the mixture. The IC 103 of the oscillation circuit 102 is a timer IC.
[0014]
The control circuit 200 includes a microcomputer 208, a comparator 216 for comparing and judging whether or not the voltage of the capacitor 115 has risen to a predetermined value or more, a display circuit 228 for informing the operator of the state of the tool body by sound or light, and the like. You. The trigger switch 12 and the head switch 25 are connected to a power supply via pull-up resistors 201 and 202 and to an input port of the microcomputer 208. The output of the microcomputer 208 is connected to display circuits such as the LEDs 225 and 227 and the buzzer 223, the oscillation circuit 102, the thyristor 114, and the like. When the microcomputer 208 learns from the output of the comparator 216 that the terminal voltage of the capacitor 115 has become equal to or higher than the predetermined value, the microcomputer 208 generates an output that turns on the transistor 213 and turns on the thyristor 114.
[0015]
The fan control circuit 300 is a circuit that controls the fan 304 that stirs the gas in the combustion chamber, and controls the operation of the fan 304 by turning on and off the FET 303 based on the output of the microcomputer 208.
[0016]
The operation of the ignition system of FIG. 1 will be described with reference to the flowchart of FIG. 2 and the time chart of FIG. In the time chart shown in the time chart of FIG. 3, Td0 is the oscillation circuit drive time, Td1 is the delay timer time, Td2 is the continuous timer time, and Td3 is the fan timer time.
[0017]
When the power is turned on, the microcomputer 208 is reset to perform an initial setting (S100). At this time, only the fan timer is counted up, and the other timers are reset to zero.
Next, in S102 and S104, it is detected whether or not the head switch 25 and the trigger switch 12 are turned on. If both are not on, the processing at the time of turning off, that is, the display circuit is turned off (S108). A fan operation check (S110) and a fan timer check (S116) are performed, and the process returns to S102 to repeat this operation.
[0018]
Next, the operation at the time of "single shot" will be described (see FIGS. 2 and 3A).
When the head switch 25 is turned on, the delay timer starts (S122), and the display circuit and the fan are driven (S124). Then, when the trigger switch 12 is closed and the delay timer counts up (S128Y), the oscillation circuit starts operating (S132). Here, since the delay timer is set to, for example, 50 to 100 ms, it normally counts up from the time when the head switch 25 is turned on to the time when the trigger switch 12 is turned on. When the voltage of the capacitor 115 becomes equal to or higher than a predetermined value (S134Y), the oscillation circuit 102 is turned off and the thyristor 114 is turned on (S136), and the fuel is ignited. After ignition, the firing timer starts counting (S138), and the oscillation circuit 102 is not turned on until the firing timer counts up.
[0019]
Next, the operation at the time of "striking" will be described (see FIGS. 2 and 3B).
When the trigger switch 12 is turned on (S104), the display circuit and the fan are driven (S106). When the tool body is pressed against the member to be fastened, the head switch 25 is turned on (S102), and the delay timer is started (S122). When the delay timer counts up (S128), the oscillation circuit 102 is turned on (S132), and when the voltage of the capacitor 115 becomes equal to or higher than a predetermined value (S134), the thyristor 114 is turned on (S136) to ignite. Thus, since the ignition is delayed by the delay timer when the fuel is injected after the head switch 25 is turned on, the ignition is performed after the fuel is sufficiently mixed, and the ignition can be reliably performed. Although not shown, between S128 and S130, it is necessary to determine whether or not the continuous timer has started, and if so, proceed to S130; otherwise, proceed to S132.
[0020]
After the ignition, the firing timer starts counting (S138). Then, when the operator tries to drive continuously and releases the tool main body from the member to be fastened together with the reaction of driving the nail, the head switch 25 opens. When the tool body is pressed against the member to be fastened again, the head switch 25 is turned on ( (S102) Even if the delay timer starts (S122) and counts up, the oscillation circuit 102 does not turn on until the consecutive timer counts up (S130). When the continuous timer counts up (S130), the oscillation circuit 102 is turned on (S132), and when the voltage of the capacitor 115 becomes equal to or higher than a predetermined value (S134), the thyristor 114 is turned on (S136), and between the discharge electrodes 117 in the combustion chamber. Causes a spark discharge to ignite the mixture.
[0021]
This is because after the spark comes out, the piston has to wait until the piston descends and strikes the nail, the piston returns, and the exhaust gas in the combustion chamber is replaced (scavenged) by fresh air. Failure to do so results in poor ignition. This time requires about 100 to 200 ms, and the continuous timer is used to secure this time. In the case of "striking", the operator may make a quick movement of hitting 3 to 5 hits per second, and this time affects the reliability of ignition.
[0022]
Practically, the time of each timer is desirably 10 to 50 ms for the delay timer, 100 to 300 ms for the continuous timer, and 5 to 15 s for the fan timer, but is not limited thereto. Note that the delay timer is for ensuring the mixing and stirring time in the combustion chamber by starting the operation of the fan after the head switch 25 is closed, and the continuous timer is for inhibiting the next ignition for a predetermined time after ignition once. Further, the fan timer is for ensuring the scavenging time of the combustion chamber after one driving is completed.
[0023]
In the above embodiment, the microcomputer is used, but the invention is not limited to the microcomputer, and it can be realized by a digital circuit or the like. Although the ignition circuit is configured to discharge rapidly after the capacitor voltage becomes constant, it may be configured to discharge rapidly after a fixed time.
[0024]
【The invention's effect】
As described above, according to the present invention, the "single-hitting" operation can be performed, and at the same time, the "consecutive-hitting" operation can be performed reliably and safely.
[Brief description of the drawings]
FIG. 1 is a block diagram showing one embodiment of an ignition system for a combustion type driving tool according to the present invention.
FIG. 2 is a flowchart for explaining the operation of the microcomputer.
FIG. 3 is a time chart for explaining the operation of FIG. 1;
FIG. 4 is a partial sectional view showing an example of a conventional combustion driving tool.
[Explanation of symbols]
12: trigger switch, 25: head switch, 100: ignition circuit, 200: control circuit, 300: fan control circuit.

Claims (8)

A combustible driving tool for driving a nail by moving a driver blade by increasing the pressure by burning combustible gas in a closed combustion chamber,
A first switch for detecting that the tool body is pressed against the workpiece to form a closed combustion chamber, a second switch operated by an operator, and regardless of the operation order of the first switch and the second switch. Control means for activating igniting means for igniting the flammable gas upon detecting that both switches have been operated. 2. A stirrer for stirring a gas in a combustion chamber in which a combustible gas is burned, wherein an operation of the stirrer is started when one of the first switch and the second switch is operated. The combustion type driving tool described. Gas supply means for supplying a combustible gas in synchronization with the operation of the first switch or the second switch, and the ignition means after a predetermined time delay from the operation of the first switch or the second switch for operating the gas supply means The combustion type driving tool according to claim 1, wherein the tool is operated. The combustion type driving tool according to claim 1 or 3, wherein the operation of the ignition means after the operation of the ignition means is prohibited for a predetermined time. The ignition means is operated after a predetermined time delay from the operation of the first switch or the second switch for operating the supply means, and the operation of the ignition means after the operation of the ignition means is prohibited for a predetermined time. The combustion type driving tool according to claim 3, wherein 2. The display device according to claim 1, further comprising: display means for notifying the worker that the driving is possible by sound or vibration, and operating the display means when either the first switch or the second switch is operated. Combustion type driving tool. At least two or more locations on the surface of the tool main body are provided with display means for informing the worker that they can be driven by light, and the display means is operated when either the first switch or the second switch is operated. The combustion type driving tool according to claim 1, wherein Display means is provided for indicating at least two locations including at least one location on the surface of the tool body excluding the gripping portion of the tool body to be capable of being driven by light, and is displayed when either the first switch or the second switch is operated. 2. A combustion driven tool according to claim 1, wherein the means is operated.

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