EP3181304B1 - Method for controlling the actuation of a gas-fixing tool and corresponding device - Google Patents

Description

Field of the invention

The invention is in the field of portable tools for fixing parts by means of nails or staples propelled by a driving piston, under the effect of the combustion of a gas.

The invention more specifically relates to a method and a device for controlling the actuation of such a tool to trigger the firing of a fastener (nail, staple).

Background of the invention

The state of the art includes documents EP-A4-1 878 540 , EP-A1-1 391,270 , WO-A1-2008 / 048294 , US-A1-2008 / 223895 , EP-A1-1 782 925 and US-A1-2010 / 243699 .

In a known manner, a gas fastening tool comprises, in a housing, an internal combustion engine for propelling a driving piston of a fastening element, such as a nail or a staple, intended for anchor in a constituent material of a work surface. The engine comprises at least one internal combustion chamber for containing a mixture of air and combustible gas ignited by an internal ignition device causes the propulsion of a piston intended to drive the fastener element to the output of a tip guide extending to the front of the housing. The combustible gas supply of the combustion chamber is effected by means of an injection member from a gas cartridge. Such a tool also comprises an actuation trigger for controlling the firing trigger to propel a fastener via the piston. Activation of this trigger by a user causes the generation of an electric arc in the combustion chamber by means of the ignition device.

The applicant has found that this type of tool can provide poor quality shots, characterized by a partial depression of the nail or the staple in the material, following the activation of the actuation trigger of the tool by an user.

In known manner, the mechanical support of the tool on a work surface triggers a preparation process at the end of which the tool is said to be "ready to shoot". This preparation process comprises the following steps: percussion of the fuel gas cartridge, filling of the combustion chamber by displacement of the gas from the cartridge at the same time purging the chamber.

Pressing the trigger during the preparation process has the effect of interrupting the filling of the combustion chamber by closing the chamber. In case of interruption of the process, the filling of the chamber and its purging are partial, so that the tool is not in optimal shooting conditions. If the user moves too quickly the support of the tool and the activation of the trigger of the tool, a poor quality shot will be triggered. Therefore, there is a need to ensure optimum firing conditions allowing reliable depressing of the fastener in the work area.

Object and summary of the invention

In order to overcome the drawbacks of the prior art mentioned above, the present invention proposes a method and an electronic ignition control device of an internal combustion chamber of a gas fixation tool, according to which the firing is triggered when activating the trigger, provided that the filling time of the combustion chamber is optimal. For this, a mechanism to prohibit the trigger firing if a time condition is not met. This condition relates to the time elapsed between the detection of a first mechanical event triggering the filling of the chamber with the gas, for example the support of the tool on the working surface, and a second mechanical event corresponding to the trigger trigger indicating the user's desire to fire.

The process according to the invention is the process according to claim 1. Advantageously, the firing of the ignition of the combustion chamber can take place only if the duration of filling of the combustion chamber between the first instant and the second instant is greater than a first predetermined threshold corresponding to a duration of optimal filling of the combustion chamber.

In the case where a user chases too quickly the support of the tool (first mechanical event) and the activation of the trigger of the tool (second mechanical event) to trigger the shot, by not respecting a minimum delay corresponding to the first threshold, the ignition of the ignition of the combustion chamber is not allowed. Indeed, if the time measured between the moment the user puts the tool on the work surface and the moment when he presses the trigger of the tool is too short, the combustion chamber will not had enough time to fill up with fuel gas to bring about quality fire.

• mesure temporelle pour mesurer le temps écoulé entre le premier instant et le deuxième instant;
• comparaison temporelle pour comparer le temps écoulé et le premier seuil prédéterminé ; et
• génération dudit signal si ledit temps écoulé est supérieur au premier seuil.

According to a particular embodiment of the invention, the step of generating the control signal comprises the following substeps:

• time measurement for measuring the elapsed time between the first instant and the second instant;
• time comparison to compare the elapsed time and the first predetermined threshold; and
• generating said signal if said elapsed time is greater than the first threshold.

• déclenchement d'une temporisation d'une durée égale audit seuil lors de la détection du premier événement mécanique; et
• génération dudit signal de commande si la détection du second événement intervient postérieurement à l'issue de la temporisation.

By preventing the triggering of the ignition of the chamber in the case where the time measured between the first and second instants is less than the first threshold, this avoids poor quality shots characterized by a depression partial nail due to lack of power. In this way, it is ensured that, upon activation of the trigger, the combustion chamber is sufficiently filled to generate an explosion or combustion power sufficient to ensure a good quality of fire. According to another embodiment of the invention, the step of generating the control signal comprises the following sub-steps:

• triggering a delay of a duration equal to said threshold when detecting the first mechanical event; and
• generating said control signal if the detection of the second event occurs later after the delay.

Advantageously, firing is allowed only if the timing has been completely elapsed, to allow a filling of the combustion chamber sufficient to ensure a quality shot at the moment the user presses the trigger (second mechanical event).

According to one particularity of the invention, the step of generating the ignition trigger command is performed only on the additional condition that the duration between the first and second mechanical events is less than a second predetermined threshold.

The second predetermined threshold corresponding to a maximum filling time beyond which the shooting conditions are no longer optimal. Thus, if the user presses the trigger too late after starting the tool (first mechanical event), the trigger control signal will not be generated so as to avoid a poor quality shot. Indeed, beyond a certain filling time, the mixing conditions of the combustion gas in the chamber are no longer optimal.

According to one particularity of the invention, firing is authorized if the effective filling time of the combustion chamber corresponding to the duration between the first and second instants is within a confidence interval whose lower and upper bounds respectively correspond to the first and second instants. and second threshold, this confidence interval being determined to guarantee optimal shooting conditions.

The method further includes an adjusting step for adjusting at least one of the thresholds, based on at least one temperature parameter.

By way of non-limiting example, the temperature parameter can be selected from any of the following parameters: ambient temperature, known as working temperature, temperature in the vicinity of the combustion chamber, temperature inside the combustion chamber , or temperature in the vicinity of another area of the tool, such as a possible evaporator.

The value of the delay time for which the shooting conditions are optimal depends on at least one of the temperature parameters above. Thus, taking into account at least one temperature parameter advantageously makes it possible to adjust more finely the value of the delay time and thus to further improve the quality of the shot.

According to one embodiment, only the first threshold is adjusted during the adjustment step, while according to another embodiment, the first and second thresholds are adjusted during the adjustment step.

Starting to generate the medium voltage ignition signal as soon as the first mechanical event is detected at the first moment allows to obtain a shot immediately, when the user presses the trigger, provided that the signal of medium ignition voltage has reached the trigger threshold value. This feature is particularly advantageous compared to known solutions of the prior art for which the medium ignition voltage is generated only after the user has pressed the trigger. For example, pressing the tool on a work surface instantly causes the start of the generation of the medium voltage ignition signal without waiting for activation of the trigger.

The method may further comprise, between the step of generating a medium ignition voltage and the step of comparing the voltage of the average ignition voltage signal, a step of converting said average ignition voltage signal.

Another advantage of the invention lies in the precision of the measurement of the average ignition voltage due to the conversion step. The improved accuracy of the measurement carried out ensures a constant energy in the spark produced regardless of the ignition device considered.

Advantageously, the conversion step converts the analog medium voltage signal into a digital value that can be processed during the conversion step.

In one embodiment, the step of generating the average ignition voltage is initiated (for example, by charging a capacitor), before the step of detecting the second mechanical event at the second instant (for example, before the user presses the trigger).

• des moyens de génération d'un signal de commande de déclenchement de l'allumage de la chambre de combustion suite à la détection du second événement mécanique, si la durée entre les premier et second événements mécaniques est supérieure à un premier seuil prédéterminé.

The present invention also relates to an electronic ignition control device of an internal combustion chamber of a gas fastening tool according to claim 7.

• means for generating a control signal for triggering ignition of the combustion chamber following detection of the second mechanical event, if the duration between the first and second mechanical events is greater than a first predetermined threshold.

• des moyens de mesure temporelle adaptés à mesurer le temps écoulé entre le premier instant et le deuxième instant ;
• des moyens de comparaison temporelle pour comparer le temps écoulé et le premier seuil prédéterminé ; et
• des moyens de génération de commande pour générer le signal de commande si ledit temps écoulé est supérieur au premier seuil.

According to a particular embodiment of the invention, the means for generating the control signal comprise:

• time measuring means adapted to measure the time elapsed between the first instant and the second instant;
• time comparison means for comparing the elapsed time and the first predetermined threshold; and
• control generating means for generating the control signal if said elapsed time is greater than the first threshold.

According to one particularity of the invention, the first detection means comprise an expansion switch controlled by the second event (activation of a detent of the tool), the second detection means comprise a support switch controlled by the first event. (support of the tool on a work surface), the trigger switch and the support switch being connected to the time measuring means.

According to another particular embodiment of the invention, the means for generating the control signal comprise delay means of a duration equal to the first threshold, the delay means being adapted to trigger the delay when the first signal is detected. mechanical event and the generation means are adapted to generate the control signal at the end of the delay.

According to a particularity of the invention, the first detection means comprise an expansion switch controlled by the activation of a trigger of the tool (second mechanical event), the second detection means comprise a support switch controlled by a support of the tool on a work surface (first mechanical event), the delay means include a timer module coupled to a timer switch connected in series between the detent switch and the backup switch.

According to a feature of the invention, the control signal generating means are adapted to generate the control signal with the additional condition that the duration between the first and second mechanical events is less than a second predetermined threshold.

According to another feature of the invention, the device further comprises adjustment means for adjusting at least one of said thresholds as a function of at least one temperature parameter.

According to another feature of the invention, the device further comprises voltage conversion means for converting the average ignition voltage into a voltage comparable to the reference trigger voltage.

According to one embodiment, the means for generating a medium ignition voltage are adapted to generate said average ignition voltage before the second detection means detect the second mechanical event at the second instant.

Advantageously, the device is arranged in a removable block.

The integration of the ignition control device in the same removable block allows maintenance and easy replacement of this block during repair or maintenance operations.

The present invention also relates to a gas fastening tool comprising an electronic ignition device according to the characteristics described above.

Brief description of the drawings

• la figure 1 illustre schématiquement un outil de fixation à gaz conformément à l'état actuel de la technique ;
• la figure 2 illustre un dispositif d'allumage de la chambre de combustion d'un outil de fixation à gaz conformément à l'état actuel de la technique ;
• la figure 3 illustre un dispositif d'allumage de la chambre de combustion d'un outil de fixation à gaz comprenant le dispositif de contrôle d'allumage électronique selon un premier mode de réalisation de l'invention,
• la figure 4 illustre les étapes du procédé de contrôle de l'allumage de la chambre de combustion selon un premier mode de réalisation de l'invention,
• la figure 5 est un chronogramme illustrant des enchaînements d'événements intervenant lors de l'utilisation d'un outil de fixation à gaz incluant le dispositif de contrôle d'allumage mettant en oeuvre les moyens de temporisation selon le premier mode de réalisation de l'invention,
• la figure 6 est un bloc-diagramme détaillé du dispositif de contrôle de l'allumage de la chambre de combustion selon le premier mode de réalisation de l'invention, et
• la figure 7 illustre des moyens de temporisation et de génération d'un signal de commande selon un deuxième mode de réalisation ; et
• la figure 8 est un chronogramme illustrant un enchaînement d'événements intervenant lors de l'utilisation d'un outil de fixation à gaz incluant le dispositif de contrôle d'allumage mettant en oeuvre les moyens de temporisation selon la deuxième réalisation.

Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the drawings which illustrate an embodiment of this embodiment which is devoid of any limiting character and in which:

• the figure 1 schematically illustrates a gas fastening tool according to the state of the art;
• the figure 2 illustrates a device for igniting the combustion chamber of a gas fastening tool according to the state of the art;
• the figure 3 illustrates a device for igniting the combustion chamber of a gas fixation tool comprising the electronic ignition control device according to a first embodiment of the invention,
• the figure 4 illustrates the steps of the ignition control method of the combustion chamber according to a first embodiment of the invention,
• the figure 5 is a timing diagram illustrating sequences of events occurring during the use of a gas fixation tool including the ignition control device implementing the delay means according to the first embodiment of the invention,
• the figure 6 is a detailed block diagram of the ignition control device of the combustion chamber according to the first embodiment of the invention, and
• the figure 7 illustrates means for delaying and generating a control signal according to a second embodiment; and
• the figure 8 is a timing diagram illustrating a sequence of events occurring during the use of a gas fastening tool including the ignition control device implementing the delay means according to the second embodiment.

detailed description

The figure 1 describes, according to the state of the art, a gas fastening tool, such as a nail gun, having a housing 1, in which there is an internal combustion engine 2 with a combustion chamber 3 for contain a mixture of air and combustible gas, the firing of which causes the propulsion of a piston intended to drive a fastener such as a nail or a staple extracted from a feed magazine 4, the fixing member being adapted to anchor in a support material at the exit of a guide-tip 5 extending at the front of the housing 1. The tool housing has an axis 6, along which move the driving piston and, in the tip guide 5, the fastening elements.

The fuel gas supply to the combustion chamber 3 is effected by means of an injection device, for example mechanical or electrical (of the solenoid valve type), from a fuel gas cartridge. The gas cartridge can be connected to a first pre-combustion chamber, followed by the combustion chamber, the latter being in connection with the piston for propelling the nails out of the tip guide.

Such a tool also comprises a handle 9 for handling and firing, on which is mounted a trigger 10 for actuating the tool intended to control the trigger firing.

This tool further comprises an electronic ignition device for igniting the combustion chamber 3, when the trigger 10 of the tool is actuated by a user.

As illustrated on the figure 2 , the electronic ignition device according to the current state of the art, comprises a low-voltage power source 20 adapted to deliver a low-voltage electrical signal V ₁ , a medium-voltage ignition generator 24 adapted to deliver a medium voltage electric ignition signal V ₂ , a high-voltage spark generator 28 adapted to deliver a high-voltage spark electrical signal V ₃ and a spark plug 29 adapted to deliver an electric arc into the combustion chamber to initiate the combustion of the gas.

Subsequently, the term "high voltage" will mean "high spark voltage" and the term "medium voltage" will mean "medium ignition voltage".

The low-voltage power source 20 is constituted, for example, by a battery delivering a DC voltage of 6V. The medium-voltage ignition generator 24 is adapted to provide a medium voltage electrical ignition signal V ₂ of an amplitude of the order of 250V, from the low voltage electrical signal V ₁ . The medium-voltage ignition generator, based on MOS transistors, is associated with a diode-based pulse transformer 25 and delivers the medium-voltage ignition signal V ₂ across a storage capacitor 26 energy. The high voltage generator comprises a transformer having a primary winding and a secondary winding for generating a high voltage signal V ₃ across the spark plug 29.

A switch 21 associated with the trigger 10 is connected in series between the low-voltage energy source 20 and the medium-voltage ignition generator 24, so that when the trigger 10 is actuated by the user, the source Low voltage energy electrically supplies the medium voltage ignition generator. Therefore, the actuation of this switch 21 causes the capacitor 26 to be charged. When the voltage across the capacitor reaches a predetermined threshold, a triggering device 27 based on an electronic component triggered by the voltage at its terminals, suddenly discharges the capacitor 26 in the winding. transformer primary of the high voltage generator 28 creating in the secondary winding of the transformer a high voltage electrical signal V3 of amplitude greater than 20 kV. It follows the generation of a spark at the spark plug 29 for ignition of the combustion chamber 3.

This ignition mechanism has the following disadvantage. If the user chases too quickly the support of the tool and the activation of the trigger to trigger fire, ignition of the combustion chamber will occur, while it is partially filled with gas, does not provide sufficient combustion power to provide quality fire which will result in partial penetration of the fasteners into the work area.

In order to guarantee optimal combustion conditions, the ignition device known from the prior art is adapted to receive an electronic ignition control device for the combustion chamber of the tool according to the invention as illustrated in FIG. figure 3 .

The ignition control device according to the invention comprises a first switch 21 controlled by the actuation of the trigger 10 (second mechanical event), a second switch 22 controlled by the support of the tip guide 5 on a work surface (first mechanical event), and a microcontroller 30 designed to interface with the first and second switches.

The second switch 22 is connected in series between the low-voltage power source 20 and the medium-voltage ignition generator 24, so that the medium-voltage ignition generator 24 is powered by the energy source at low voltage 20, when the guide tip 5 is pressed against the work surface at a first time t ₁ . The microcontroller 30 is designed to interface with the second switch to receive a signal V ₂₂ from detecting the support of the tool at the first instant t ₁ from which the microcontroller measures the elapsed time.

The first switch 21 is connected in series with a low-voltage power source 20 ', so as to deliver to the microcontroller a detection signal V ₂₁ for actuating the trigger, when the trigger 10 is actuated by the user to a second moment t ₂ . The microcontroller 30 is designed to interface with the first switch 21, so as to receive the operation detection signal V ₂₁ at the second instant t ₂ .

The microcontroller 30 is designed to receive in real time a charge signal V ₂ supplied across the capacitor 26, convert this signal into a converted signal V ' ₂ and compare the latter with a trigger threshold voltage V _d (means conversion and comparison 32).

The microcontroller 30 is adapted to measure a delay Δt between the first instant t ₁ and the second instant t ₂ and to compare this delay with a reference timing value.

The microcontroller 30 is also adapted to supply a control signal S to a controlled tripping device 27 'disposed between the medium voltage ignition generator 24 and the high voltage generator 28 (generating means of the control 35).

The method of controlling the electronic ignition of the combustion chamber 3 according to the present invention will now be described with reference to figures 3 and 4 . The figure 4 illustrates the steps of the ignition control method of the combustion chamber according to one embodiment of the invention.

The support of the tip-guide 5 of the tool against a working surface, at a first instant t ₁ , is an example of a first mechanical event which causes the percussion of the fuel gas cartridge and the displacement of this gas towards the pre-combustion chamber and the combustion chamber 3, at the same time purging these chambers. Thus, at this first moment t _{1 is} performed the start of the filling and purging of the chamber of combustion by gas. The mechanical support of the tool on the work surface has the effect of switching the second switch 22 associated with the guide-tip 5. This support is detected at the first moment t ₁ , during a first detection step E ₁ , by the microcontroller 30 interfaced to the second switch. The microcontroller comprises a memory intended to record a first time value corresponding to the first instant t ₁ .

At this same first instant t ₁ , the tilting of the second switch 22 has the effect of supplying power to the generator of medium ignition voltage from the low-voltage energy source. The electrical medium voltage ignition signal V ₂ is generated during a medium ignition voltage generation step E ₂ , during which the capacitor 26 is charged.

Advantageously, starting the charge of the capacitor as soon as the tool is pressed against the work area offers the possibility of pre-charging the capacitor before the user presses the trigger. This feature of the invention avoids a delay between the moment when the trigger is activated and the moment when the average ignition voltage is generated, knowing that the time required to generate the average ignition voltage is generally between 30 ms. and 60 ms. In this way, a shot can be obtained instantly, as soon as the user presses on the trigger, which is not the case with the known gas fastening tools of the prior art for which the charge of the capacitor is initiated only after pressing the trigger causing a delay of 30 to 60 ms.

According to a feature of the present invention, the microcontroller is adapted to measure the electrical signal of medium ignition voltage V ₂ during a voltage measurement step E ₃ .

The microcontroller is adapted to convert this measured signal into a converted signal V ' ₂ of amplitude comparable to the trigger threshold voltage V _d during a conversion step E ₄ .

The microcontroller is adapted to compare the converted signal V ' ₂ with respect to a trigger threshold voltage V _d during a step of voltage comparison E ₅ . Exceeding this threshold voltage is necessary but not sufficient to trigger the ignition of the combustion chamber.

At a second time t ₂ , the user presses the trigger 10 for actuating the tool indicating a desire of the user to trigger a shot. This second mechanical event has the effect of closing the combustion chamber and thus stop its filling with gas. Pressing the trigger causes the first switch 21 to topple over, this switchover being detected by the microcontroller 30 during a second detection step E ₇ . The microcontroller 30 is adapted to measure, at the same second instant t ₂ , the time elapsed since the first instant t ₁ . This measurement is performed during a time measurement step E ₉ . This delay Δt = t ₂ -t ₁ corresponds to the actual filling time Δt of the combustion chamber by the gas, between the moment when the user put the tool mechanically supported on the work surface and the moment when the The user has pressed the trigger to activate the trigger. During a time comparison step E ₁₁ , the delay Δt measured between the first instant t ₁ and the second instant t ₂ , is compared to a first predetermined threshold ΔT _{R 1} to guarantee optimal firing conditions. This first value Δt _R1 corresponds to the minimum gas filling time to obtain a combustion power necessary for a complete depression of the fastener element in the working area.

According to one particularity of the invention, ignition of the combustion chamber can only be triggered if the effective filling time Δt is greater than the first threshold Δt _R1 . Thus, it avoids that a support on the relaxation too fast causes a poor quality shot.

For example, if the action on the trigger was too anticipated by the user and did not allow time for the mixture of air and fuel gas to sufficiently fill the volume of the combustion chamber, the spark 'is not triggered, to prevent an explosion of poor quality generates imperfect nailing and unnecessary damage to the part to fix.

According to a particular embodiment, there is also a second predetermined threshold Δt _R2 , corresponding to a filling time of the combustion chamber beyond which the firing conditions are no longer optimal.

Thus, according to a particular embodiment of the invention, the method comprises an additional temporal comparison step, during which it is further tested that the measured delay Δt does not exceed the second threshold Δt _R2 , so as to guarantee a shot of good quality.

When this additional condition is applied, firing can only be fired if the measured delay Δt = t ₂ -t1 is within a confidence interval whose lower and upper bounds correspond respectively to the minimum and maximum delay values, such that: Δt _R1 ≤ Δt ≤ Δt _R2 .

The microcontroller 30 is adapted to store the value of the first threshold Δt _R1 (first value) and optionally the value of the second threshold Δt _R2 (second value), in which case the first and second values define the confidence interval guaranteeing combustion conditions. optimal for a quality shot.

According to a feature of the present invention, the value of the first threshold Δt _R1 and / or the second Δt _R2 threshold is adjusted during an adjustment step (not shown), as a function of at least one temperature parameter T such as that the ambient temperature called working temperature, as provided by a temperature sensor 40.

According to a particular embodiment, the value of the first threshold is adjusted. According to another embodiment, the value of the second threshold is adjusted alone or in combination with the adjustment of the value of the first threshold, so as to adjust the confidence interval, according to the fluctuations of the temperature T.

According to a feature of the invention, this adjustment step is performed by the microcontroller. The temperature sensor 40 is fixed, so as to measure in real time the ambient temperature called working temperature. In the case where the tool has an evaporator, the temperature sensor 40 can be fixed on the evaporator, if heat transfer takes place between the combustion chamber and the evaporator.

Such an adjustment advantageously makes it possible to take into account the temperature conditions to cause an optimal combustion according to the physicochemical properties of the gas used. For example, the value of the first threshold is set at 0.40 seconds and the value of the second threshold is set at 0.150 seconds using butene / propene or a mixture of alkenes as fuel gas, for a use temperature between -10 ° C and 50 ° C.

As soon as the effective filling time Δt of the combustion chamber is within the confidence interval ( first condition ) and the ignition medium generator supplies at the terminals of the capacitor a voltage greater than the threshold voltage of tripping V _d ( second condition ), the triggering of ignition is controlled by the microcontroller.

Thus, when the two above conditions are met at the end of a Boolean logic step E ₁₃ (ET), the microcontroller provides, during a sending step E ₁₅ , a trigger control signal S to the controlled tripping device 27 'to cause ignition of the combustion chamber.

Advantageously, the firing is triggered only if the effective filling time of the combustion chamber is within the confidence interval corresponding to an optimal filling of the combustion chamber by the fuel gas and if the voltage at the terminals capacitor exceeds the trip voltage threshold. In this way, it is guaranteed that when the trigger is activated by the user, the combustion chamber is sufficiently filled to generate a power necessary to ensure good shooting quality.

The controlled tripping device 27 'is a conventional device based on electronic components initiated by the voltage across its terminals (V> V _d ). It is distinguished from the triggering device of the prior art 27 in that it is designed to be controlled by the microcontroller so as to activate the high voltage generator on receipt of the trigger control signal S.

According to the embodiment described above, the first and second conditions must be met to enable the generation and sending of the firing trigger S. However, in other embodiments, only the first condition must be met in order to trigger the shot.

According to an alternative embodiment, if the first or second condition, or if the first and second conditions are not met when the user presses the trigger 10 to trigger the shot, the step of generating and S ₁₅ sending of the S command is deferred pending the fulfillment of all the expected conditions.

For example, assuming that the user chains the first and second mechanical events too quickly, respectively corresponding to the support of the tool on the work area and the support on the trigger, so that the chamber of combustion did not have time to fill up optimally (cf. Fig. 5 "Chaining B"), pressing the trigger does not instantly cause the closing of the combustion chamber, so that it remains open for a further period of time to complete the filling of the chamber. This additional duration Δt - Δt _{R {1,2}} corresponds to the difference between the actual filling time Δt = t ₂ -t ₁ and the first threshold Δt _R1 (or the second threshold Δt _R2 or any other value between the first and second thresholds).

The steps of the method according to the invention, including the detection steps E ₁ , E ₂ , measurement E ₃ and comparison E ₁₁ time, generation E ₁₅ of a control, voltage conversion E ₄ , measurement E ₃ and comparison E ₅ voltage adjustment, described above are implemented by means of the microcontroller 30. The skilled person will understand that means equivalent to the microcontroller may be employed for carrying out these steps without departing from the scope of the present invention.

• S1 : appui mécanique de l'outil sur la surface de travail ;
• S2: activation du deuxième interrupteur 22 ;
• S3 : activation du premier interrupteur 21 ;
• S4 : préparation de l'allumage comprenant la génération d'une moyenne tension d'allumage ; et
• S5 : génération de l'étincelle par la bougie 29.

The invention will now be described with reference to the chronogram of the figure 5a , Which still result from other benefits. This timing diagram illustrates the sequencing of different events and / or phases involved in the use of the tool incorporating the control device according to the invention:

• S1: mechanical support of the tool on the work surface;
• S2: activation of the second switch 22;
• S3: activation of the first switch 21;
• S4: ignition preparation comprising generating a medium ignition voltage; and
• S5: generation of the spark by the candle 29.

The active state and the inactive state of the phases S1-S5 are designated respectively by ON and OFF on the figure 5 . The support of the tool on the work area at the first moment t ₁ marks the beginning of the preparation phase of the tool, during which the combustion chamber fills with combustible gas. At the same first instant t ₁ , the second switch is activated causing the start of the generation of the average ignition voltage by the generator of medium ignition voltage and the start of the charge of the capacitor. After a filling time greater than the first threshold Δt _R1 from the first moment t ₁ , the combustion chamber is sufficiently filled with gas to allow quality shooting. At time t ₁ + Δt _R1 , the tool is ready for shooting in optimal conditions.

As an illustration, it is considered that the preparation time of the tool at the end of which the combustion chamber is optimally filled corresponds to the minimum filling time Δt _R1 . However, this duration of may be set to any other value between the first and second thresholds.

When the user presses the trigger 10 at the second instant t ₂ , the microcontroller 30 measures a time interval Δt = t ₂ -t ₁ greater than the preparation time of the tool corresponding to the first threshold ΔT _R1 (first condition fulfilled) . At this same second instant t ₂ , it is assumed that the capacitor 26 has had sufficient time to charge. In this case, the voltage measured by the microcontroller is greater than the trigger threshold voltage V _d (second condition fulfilled). Thus, the generation of the medium ignition voltage is completed when the user presses the trigger 10. The first and second conditions being fulfilled, the firing is authorized: the microcontroller 30 sends the trigger command S to the controlled triggering device 27 'which induces the generation of the high voltage signal and the spark (case of the sequence A).

• le premier interrupteur 21 piloté par la mise en appui mécanique de l'outil sur une surface de travail et recevoir le signal V₂₁ de détection de la mise en appui mécanique de l'outil au premier instant t₁,
• le deuxième interrupteur 22 piloté par l'actionnement de la détente 10 de l'outil par l'utilisateur et recevoir le signal V₂₂ de détection de l'appui sur la détente 10 au deuxième instant t₂,
• le capteur de température 40 destiné à fournir un paramètre de température T ambiante de travail,
• le condensateur de charge 26, et
• le dispositif de déclenchement de l'allumage 27'.

In the case where the microcontroller measures a time interval Δt '= t ₂ ' -t ₁ 'between the first moment t ₁ ' where the tool is placed in support and the second t ₂ 'where the user presses the trigger less than the minimum duration of preparation of the tool (ΔT _R1 first threshold), the preparation of the tool is interrupted before reaching a minimum filling of the chamber by the gas (case of the sequence B). In this case, the firing is not allowed by the microcontroller 30 which sends no trigger command to the controlled tripping device 27 '. The figure 6 is a schematic block diagram of an ignition control device of a combustion chamber for a gas fastening tool. This control device has inputs / outputs for interfacing with:

• the first switch 21 controlled by the mechanical support of the tool on a work surface and receive the signal V ₂₁ for detecting the mechanical support of the tool at the first moment t ₁ ,
• the second switch 22 controlled by the actuation of the trigger 10 of the tool by the user and receiving the signal V ₂₂ for detecting the support on the trigger 10 at the second instant t ₂ ,
• the temperature sensor 40 intended to provide a working temperature parameter T,
• the charge capacitor 26, and
• the triggering device of the ignition 27 '.

• des moyens de mesure 34.1 pour mesurer l'intervalle de temps Δt entre le premier instant t₁ et le deuxième instant t₂, les premier et deuxième instants étant enregistrés par lesdits moyens de mesure respectivement lors de la réception du signal V₂₁ de détection de la mise en appui mécanique de l'outil et lors de la réception du signal V₂₂ de détection de l'appui sur la détente 10,
• des moyens de comparaison 34.2 pour comparer l'intervalle de temps Δt mesuré par rapport au premier seuil Δt_R1 et au deuxième seuil Δt_R2 et fournir un signal de comparaison S34 si l'intervalle de temps mesuré Δt est compris entre les premier et deuxième seuils,
• des moyens d'ajustement 34.4 pour ajuster les valeurs des premier Δt_R1 et deuxième Δt_R2 seuils,
• des moyens de stockage 34.3 pour stocker des informations de configuration telles que les valeurs de premier Δt_R1 et deuxième Δt_R2 seuils, des règles d'ajustement de ces valeurs en fonction d'au moins un paramètre de température ambiante de travail.

This device further comprises a temporal measurement and comparison device 34 comprising:

• measuring means 34.1 for measuring the time interval Δt between the first instant t ₁ and the second instant t ₂ , the first and second instants being recorded by said measuring means respectively when receiving the signal V ₂₁ of detection of the mechanical support of the tool and when receiving the signal V ₂₂ detecting the support on the trigger 10,
• comparison means 34.2 for comparing the time interval Δt measured with respect to the first threshold Δt _R1 and the second threshold Δt _R2 and providing a comparison signal S34 if the measured time interval Δt is between the first and second thresholds ,
• adjustment means 34.4 for adjusting the values of the first Δt _R1 and second Δt _R2 thresholds,
• storage means 34.3 for storing configuration information such as the values of first Δt _R1 and second Δt _R2 thresholds, rules for adjusting these values as a function of at least one working ambient temperature parameter.

• des moyens de conversion 32.1 pour convertir le signal de moyenne tension d'allumage V₂ en un signal V'₂ d'amplitude comparable à la tension de seuil de déclenchement V_d,
• des moyens de comparaison 32.2 pour comparer le signal converti V'₂ par rapport à la tension de seuil de déclenchement V_d, et
• des moyens de stockage 32.3 pour stocker des paramètres de configuration tels que la valeur de la tension de seuil de déclenchement V_d.

This device further comprises a voltage measuring and comparing member 32 comprising:

• conversion means 32.1 for converting the average ignition voltage signal V ₂ into a signal V ' ₂ of amplitude comparable to the trigger threshold voltage V _d ,
• comparison means 32.2 for comparing the converted signal V ' ₂ with respect to the trigger threshold voltage V _d , and
• storage means 32.3 for storing configuration parameters such as the value of the trigger threshold voltage V _d .

This device further comprises a decision element 35 connected to the voltage comparison means 32.2 and to the temporal comparison means 34.2, the decision member being adapted to generate the control signal S intended for the controlled trigger 27 'on receipt of the a signal emitted by the two measuring and comparison elements 32 and 34 indicating that both conditions are fulfilled.

According to another feature of the invention, the electronic ignition control device according to the invention is designed to be arranged in a single removable block to implement the steps of the method according to the invention. Such an arrangement allows maintenance and easy replacement of the block during repair or maintenance operations.

According to a preferred embodiment of the invention, the measuring and comparison members 32 and 34 and the decision member 35 are implemented by a microcontroller. However, the latter may be replaced by any other device designed to perform the functions described above.

According to a second embodiment as schematically illustrated in FIG. figure 7 , the delay means are implemented by means of a delay module 34 'controlling a delay switch 23, connected in series between a support switch 22' controlled by the support of the tool and secondly a trigger switch 21 'controlled by the support of the trigger 10.

The means for generating a control signal for triggering the ignition of the combustion chamber are constituted by the means of delay, the backup switch, the expansion switch, the delay switch, and the voltage source 20.

The first detection means for detecting the pressing of the tool against a working surface at the first instant t ₁ (first mechanical event) are formed by the support switch 22 'connected to the voltage source 20.

The second detection means for detecting the support on the trigger 10 are formed by the trigger switch 21 'connected in series with the support switch.

The delay module 34 'is adapted to trigger the flow of a delay time Δt _R , on reception of a detection signal V' ₂₂ supplied by the voltage source 20. This detection signal is provided when the support switch 22 'is closed when the tool is placed on the work surface at the first moment t ₁ (first mechanical event).

The delay time Δt _R is predefined in the delay module 34 '. Advantageously, the value of the delay time is set in a confidence interval between the first Δt _R1 and second Δt _R2 thresholds respectively corresponding to first and second timing values, so that ΔT _R1 <Δt _R <Δt _R2 to ensure optimal shooting conditions as described above.

According to a particular feature of the invention, the value of the delay time Δt _R can be adjusted in real time, as a function of at least one temperature parameter T, such that the ambient temperature known as the working temperature, this parameter being delivered as described above by the sensor 40 to further improve shooting conditions.

The invention will now be described with reference to the figure 8 which illustrates a series of events occurring when using the tool equipped with an ignition control device according to the second mode of production. For a switch, the state "ON" indicates that it is closed (activated), while the state "OFF" indicates that it is open.

According to one particularity of the invention, the firing triggering command of the tool can not be generated until the delay time Δt _R has not been completely elapsed by the timing module 34 ', starting from the closing the support switch 22 'at the first moment t ₁ .

After expiration of the delay time, at time t ₁ + Δt _R , the filling of the combustion chamber with the fuel gas is optimal. At this time, the delay module 34 'causes the closing of the delay switch 23, so that the electrical signal coming from the voltage source 20 is transmitted at the output of the delay switch 23.

Pressing the trigger 10 of the tool causes the closing of the trigger switch 21 '.

If the pressure on the trigger occurs before the expiry of the delay time, at a time t ' ₂ <t ₁ + Δt _R , the trigger switch 21' closes while the timer switch 23 'remains open. In this case, the voltage signal at the output of the biasing switch 22 'can not be transmitted to the trigger switch. Thus, the firing trigger command can not be generated, as long as the timer module 34 'does not close the timer switch 23.

If the pressure on the trigger occurs after the expiry of the delay time, at a time t ₂ > t ₁ + Δt _R , the support switch 22 ', the timer switch 23 and the switch 21 'are all closed ("ON" state), so that the electrical signal from voltage source 20 is provided at the output of the trigger switch 21'. The firing trigger command can then be generated.

In this case, it should be noted that the triggering of the firing does not take place directly at the expiry of the delay time at time t ₁ + Δt _R but after a lapse of time W from time t ₁ + Δt _R at the time of pressing the trigger at time t ₂ .

According to one particularity of the invention, it will be possible to prevent the triggering of the firing if this lapse of time W exceeds a certain threshold value, beyond which the firing conditions of the combustion chamber are no longer optimal to guarantee a firing. quality.

In this case, the delay module 34 'is adapted to trigger another delay from the instant (t ₁ + Δt _R ) where it has caused the closing of the delay switch, to make sure that the shot it is no longer possible after a duration W _max , such that t ₂ -t ₁ = W _max + Δt _R ≤ Δt _R2 .

According to one particularity of the invention, the delay switch 23 goes from the closed state ON to the open state OFF after a duration Z, to allow a next shot. The changeover from the closed state to the open state of the delay switch 23 can be controlled by the delay module 34 ', or by a new press on the trigger 10 of the tool, following the sending of a shot trigger command.

As previously described with reference to Figures 3-6 , the trip command for the controlled trip device 27 'can be generated with the additional condition that the average ignition voltage is greater than the reference trigger voltage V _d . The verification of this condition is performed by means of the voltage comparator 32 or any other equivalent device.

Claims (14)

1. Method for controlling the electronic ignition of an internal combustion chamber (3) of a gas-powered fixing tool, characterized in that it comprises the following steps:

   • detection (E₁) of a first mechanical event at a first instant (t₁) ;

   • detection (E7) of a second mechanical event at a second instant (t2);

   • generation of a control signal (S) for triggering the ignition of the combustion chamber following the detection of the second mechanical event, if the time (Δt) between the first and second mechanical events is greater than a first predetermined threshold (Δt_R1),

   characterized in that it further comprises:

   • a step of generation (E₂) of a medium ignition voltage (V_z) initiated as soon as the first mechanical event is detected at the first instant (t₁) ;

   • a step of voltage comparison (E₅) to compare said medium ignition voltage relative to a reference trigger voltage (V_d),

   and in that said trigger control (S) is generated on the additional condition that the medium ignition voltage (V₂) has an amplitude greater than the reference trigger voltage (V_d).
2. Method according to Claim 1, characterized in that the step of generation of said control signal (S) comprises the following substeps:

   • time measurement (E₃) to measure the elapsed time (Δt) between said first instant (t₁) and said second instant (t₂);

   • time comparison (E₁₁) to compare said elapsed time (Δt) and said first predetermined threshold (Δt_R1); and

   • generation of said signal if said elapsed time is greater than the first threshold (Δt_R1).
3. Method according to Claim 1, characterized in that the step of generation of said control signal (S) comprises the following substeps:

   • triggering of a timeout of a time equal to said threshold upon the detection of the first mechanical event; and

   • generation of said control signal if the detection of the second event occurs after the timer times out.
4. Method according to any one of Claims 1 to 3, characterized in that the step of generation (E₁₅) of the ignition triggering control (S) is performed only on the additional condition that the time (Δt) between the first and second mechanical events is less than a second predetermined threshold (Δt_R2).
5. Method according to any one of Claims 1 to 4, characterized in that it further comprises an adjustment step to adjust said threshold (Δt_R1) or at least one of the thresholds (ΔT_R1; Δt_R2) as a function of at least one temperature parameter (T).
6. Method according to any one of the preceeding claims wherein the step of generation of the medium ignition voltage (E2) is initiated before the step of detection (E7) of the second mechanical event at the second instant (t2).
7. Device for controlling electronic ignition of an internal combustion chamber of a gas-powered fixing tool, comprising:

   • first detection means (30, 22, V₂₂) to detect a first mechanical event at a first instant (t₁);

   • second detection means (30, 21, V₂₁) to detect a second mechanical event at a second instant (t₂);

   • means for generating a control signal (S) for triggering the ignition of the combustion chamber following the detection of the second mechanical event, if the time (Δt) between the first and second mechanical events is greater than a first predetermined threshold (Δt_R1).

   characterized in that it further comprises:

   • means for generating a medium ignition voltage (V₂) suitable for generating said medium voltage, as soon as the first mechanical event is detected at the first instant (t₁);

   • voltage comparison means (32.2) to compare the medium ignition voltage (V₂) relative to a reference trigger voltage (V_d),

   and in that the means for generating (35) the trigger control are suitable for generating said control (S), if the amplitude of the medium ignition voltage (V₂) is greater than the reference trigger voltage (V_d).
8. Device according to Claim 8, characterized in that the means for generating said control signal (S) comprise:

   • time measurement means (34.1) suitable for measuring the elapsed time (Δt) between said first instant (t₁) and said second instant (t₂) ;

   • time comparison means (34.2) to compare said elapsed time (Δt) and said first predetermined threshold (Δt_R1); and

   • control generation means (35) to generate said control signal if said elapsed time (Δt) is greater than said first threshold (Δt_R1).
9. Device according to Claim 8, characterized in that

   • the means for generating said control signal (S) comprise timer means of a time equal to said first threshold, said timer means being suitable for triggering said timer upon the detection of the first mechanical event; and in that

   • said generation means are suitable for generating said control signal after the timer times out.
10. Device according to any one of Claims 8 to 10, characterized in that said means for generating the control signal are suitable for generating said control signal on the additional condition that the time (Δt) between the first and second mechanical events is less than a second predetermined threshold (Δt_R2).
11. Device according to any one of Claims 8 to 11, characterized in that it further comprises

    • adjustment means (34.4) for adjusting at least one of said thresholds (Δt_R1, Δt_R2) as a function of at least one temperature parameter (T).
12. Device according to one of Claims 8 to 11 wherein the means of generation of a medium ignition voltage (V₂) are adapted to generate said medium ignition voltage (V₂) before the second means of detection (30, 21, V₂₁) detect the second mechanical event at the second instant (t₂) .
13. Device according to any one of Claims 8 to 12, characterized in that it is arranged in a removable block.
14. Gas-powered fixing tool, characterized in that it comprises an electronic ignition control device according to any one of Claims 7 to 13.

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