JP4055509B2 - Combustion type driving tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a combustion type driving tool, and in particular, controls ignition timing for starting combustion.
[0002]
[Prior art]
Combustion-type driving tools are disclosed in Japanese Patent Publication No. 1-334753, Japanese Patent Publication No. 4-48589, Japanese Patent Publication No. 3-25307, Japanese Patent Publication No. 4-11337, Japanese Patent Publication No. 64-9149, Japanese Patent Publication No. 3-25307, and the like.
[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 that is a first switch for detecting that the tool body 20 is pressed against the fastened member 27 and a sealed combustion chamber 5 is formed, and a second switch for the operator to perform a driving operation. There is a trigger switch 12, and the combustion chamber 5 is closed by pressing the tool body 20 against the fastened member 27. At the same time, combustible gas in the gas cylinder 7, that is, fuel 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 to rotate.
[0004]
In this state, when the trigger switch 12 is pulled, the ignition circuit is activated to cause a spark discharge between the spark plugs 9 in the combustion chamber 5 and ignite the mixture. Then, the piston 10 in the cylinder 4 is driven by the explosion and expansion of the combustion gas and the piston 10 descends, and the driver blade 16 at the tip of the piston 10 is fed with a nail or the like fed onto the shaft of the driver blade 16 to the fastened member 27. Type in.
[0005]
When the piston 10 is lowered 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 at the upper portion of the combustion chamber 5 and the piston 10. When exhausted to atmospheric pressure, it is sealed by a check valve located outside the exhaust hole below the cylinder 4. Even in this state, the combustion chamber 5 is hot, but this is agitated by the fan 6 in the combustion chamber 5 and cooled by transferring heat to the combustion chamber 5 and the inner peripheral surface portion of the cylinder 4. Then, due to the rapid cooling of the combustion gas, the sealed space above the piston 10 becomes 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 up from below by the differential pressure, and returns to the initial position. Further, when the tool body 20 is lifted from the fastened member 27, the combustion chamber 5 is opened to the atmosphere, and by the action of the fan 6, the combustion gas in the combustion chamber 5 is scavenged and replaced with fresh air. Return to the state where you can shoot.
[0006]
As an ignition system, as disclosed in US Pat. No. 5,133,329, a head switch 25 for detecting that the tool body 20 is pressed against the fastened member 27 and a trigger switch 12 operated by an operator are provided, and the head switch 25 is closed. If the trigger switch 12 is closed while the head switch 25 is closed, ignition is possible, but if the trigger switch 12 is closed while the head switch 25 is open, ignition is impossible.
[0007]
These are so-called “single-shot” operations in which the tool body 20 is pressed against the fastened member 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 "single shot", every time one nail is driven, the finger must be pulled apart, that is, the trigger switch is turned on and off repeatedly, the work speed is slow, and the work efficiency is low due to the fatigue of the worker. There was a problem. And in the said structure, there existed a fault that what is called a "continuous hitting" operation | movement which drives continuously by pressing a tool main body against a to-be-fastened member intermittently in the state which pulled the trigger switch.
[0009]
An object of the present invention is to provide a combustion-type driving tool that eliminates the above-mentioned drawbacks of the prior art and enables "single shot" operation and "repetitive shot" operation.
[0010]
In order to enable the “repetitive firing” operation, the stirring means is turned on after either the first switch or the second switch is turned on, and the first switch is turned on regardless of the turn-on order of the first switch and the second switch. The ignition means is turned on when the switch and the second switch are turned on, and the stirring means is stopped when both the first switch and the second switch are turned off.
[0011]
Further, the ignition means is turned on, that is, the ignition time is delayed until the stirring and mixing is delayed by a predetermined time from the ON operation of the first switch or the second switch. Further, after the ignition means is turned on, the ignition means is prohibited from being turned on again for a predetermined time, that is, the ignition is not performed until the driving is completed and the driving can be performed again. To be done.
[0012]
In addition, when the first and second switches are operated, the operator is alerted by light, sound, or vibration to alert the operator and prevent accidents due to carelessness. In the case of light, by providing at two or more locations, the display light can be visually observed regardless of the state of the tool body.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of an ignition system. It includes 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 switches the switching transistor 105 by the oscillation circuit 102, boosts the voltage by the booster transformer 106, and rectifies the voltage by the diodes 107 and 108, thereby accumulating charges in the capacitor 115. When the electric charge is accumulated in the capacitor 115, the thyristor 114 is turned on, and the electric charge of the capacitor 115 is rapidly discharged, the voltage is increased through the high voltage transformer 116, and discharge is caused 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 that compares and determines whether or not the voltage of the capacitor 115 has risen above a predetermined value, a display circuit 228 that notifies the operator of the state of the tool body with sound or light, and the like. The The trigger switch 12 and the head switch 25 are connected to a power source through pull-up resistors 201 and 202 and are connected 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 knows from the output of the comparator 216 that the terminal voltage of the capacitor 115 has become a predetermined value or more, it generates an output that turns on the transistor 213 and turns on the thyristor 114.
[0015]
The fan control circuit 300 controls the fan 304 that stirs the gas in the combustion chamber. The fan control circuit 300 controls the operation of the fan 304 by controlling the FET 303 on and off 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 FIG. 3, Td0 is the oscillation circuit driving 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 and an initial setting (S100) is performed. 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 turned 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, a delay timer is started (S122), and the display circuit and the fan are driven (S124). 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 is normally counted up from when the head switch 25 is turned on until the trigger switch 12 is turned on, and since it is a short time for the operator, there is no sense of incongruity. 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 continuous timer starts counting (S138), and the oscillation circuit 102 is not turned on until the continuous timer counts up.
[0019]
Next, the operation at the time of “continuous firing” 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 exceeds a predetermined value (S134), the thyristor 114 is turned on (S136) to ignite. Thus, when fuel is injected after the head switch 25 is turned on, the ignition is delayed by the delay timer. Therefore, the fuel is ignited after being sufficiently mixed, and ignition can be performed reliably. Although illustration is omitted, it is necessary to determine whether or not the repetitive timer has started between S128 and S130. If it has started, the process proceeds to S130, and if not, a determination step to proceed to S132 is required.
[0020]
After ignition, the continuous timer starts counting (S138). Then, when the operator tries to drive continuously, the head switch 25 is opened when the tool body is moved away from the fastened member together with the reaction of driving the nail, and when the tool body is pressed against the fastened member again, the head switch 25 is turned on ( Even if the delay timer starts (S122) and counts up, the oscillation circuit 102 is not turned on until the continuous timer counts up (S130). When the repetitive 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. This causes a spark discharge to ignite the mixture.
[0021]
This is because after the spark has come out, it is necessary to wait for the piston to descend and drive the nail, the piston to return, and the exhaust gas in the combustion chamber to be replaced with new air (scavenging). This is because failure to do so results in poor ignition. This time requires about 100 to 200 ms, and it is the continuous timer that secures this time. This is because, in the case of “repetitive firing”, the worker may make a quick movement of hitting 3 to 5 per second, and this time affects the reliability of ignition.
[0022]
In practice, it is desirable that the time of each timer is 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. The delay timer is for securing the mixing and stirring time in the combustion chamber after the head switch 25 is closed and ensuring the mixing and stirring time in the combustion chamber. The continuous timer is for prohibiting the next ignition for a predetermined time after ignition. Furthermore, the fan timer is for ensuring the scavenging time of the combustion chamber after the completion of one driving.
[0023]
In the above embodiment, a microcomputer is used. However, the present invention is not limited to the microcomputer, and can be realized by a digital circuit or the like. Further, the ignition circuit is configured to rapidly discharge after the capacitor voltage becomes constant, but this may be configured to rapidly discharge after a certain time.
[0024]
As described above, according to the present invention, when one switch is turned on and then the other switch is turned on, driving can be performed, and when one switch is turned on, the stirring means is Since the ON state is maintained, the transition to the next driving can be performed smoothly. Further, by turning on the ignition means with a predetermined time delay after the one switch is turned on, the fuel can be reliably ignited after being sufficiently mixed. Furthermore, after the ignition means is turned on, the ignition means is prohibited from being turned on again for a predetermined time, so that the gas in the combustion chamber can be exhausted before the next driving operation. Can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an 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 cross-sectional view showing an example of a conventional combustion type driving tool.
[Explanation of symbols]
12: trigger switch, 25: head switch, 100: ignition circuit, 200: control circuit, 300: fan control circuit.

Claims (6)

A combustion type driving tool that burns combustible gas in a sealed combustion chamber to increase pressure, and moves the driver blade by the pressure increase to drive a nail,
A first switch for detecting that a sealed combustion chamber is formed by pressing the tool body against the material to be fastened, a second switch operated by an operator, and a stirring means for stirring the gas in the combustion chamber; Ignition means for igniting the combustible gas, and control means for operating the stirring means and the ignition means,
The control means turns on the stirring means after one of the first switch and the second switch is turned on, and then turns on the first switch regardless of the turn-on order of the first switch and the second switch. and turning on the ignition means when said second switch is turned on, further, a feature of the stirring means be stopped when both the first switch and the second switch is turned off Combustion type driving tool.   Gas supply means for supplying the combustible gas to the combustion chamber when the combustion chamber is formed;
  The control means turns on the stirring means after supplying the combustible gas, and when the second switch or the first switch is turned on after the first switch or the second switch is turned on. 2. The combustion type driving tool according to claim 1, wherein the ignition means is turned on after a predetermined time delay.   3. The combustion type according to claim 1, wherein the control unit prohibits the ignition unit from being turned on again for a predetermined time after the ignition unit is turned on. Driving tool.   Informing means for notifying the operator that the driver can be driven by sound or vibration is provided, and the control device turns on the informing means when either the first switch or the second switch is turned on. The combustion type driving tool according to any one of claims 1 to 3, wherein:   Display means for notifying the operator that light can be driven in at least two places on the surface of the tool body is provided, and the control means is configured to turn the first switch or the second switch on when the first switch or the second switch is turned on. The combustion type driving tool according to any one of claims 1 to 3, wherein the display means is turned on.   Display means for notifying at least one place on the surface of the tool body excluding the tool body gripping portion that light can be driven in at least two places is provided, and the control means is either the first switch or the second switch. The combustion type driving tool according to any one of claims 1 to 3, wherein the display means is turned on when the power is turned on.

Images