Fuel metering system for a fastening tool and fastening tool comprising such a system

Abstract

Fuel metering system (1) for a fastening tool such as a nail gun, said system (1) comprising a fuel tank (2) and a metering box (3) configured to be filled from the fuel tank with a predetermined dose of fuel and to permit, on a single activation of the tool, the passage of said predetermined dose of fuel to a combustion chamber (4) of the tool.

Description

Technical field of the invention

[0001] The present invention relates to combustion-powered fastening tools, that is, tools operating with a combustion chamber fueled by a combustible material, such as a nail gun. In particular, the invention relates to a fluid fuel metering system for such a fastening tool.

[0002] The present invention aims to constitute a dosing system which is integrated into the fuel supply mechanism of the tool upstream of the combustion chamber. Technical background

[0003] Fluid supply systems such as those described in US documents 6,302,297 and EP0597241 allow fuel to be supplied from a reservoir, for example held in a cartridge, to the combustion chamber of the tool, by means of a mechanically operated valve, for a duration determined by a timer.

[0004] Since the fuel is injected continuously for the duration of the opening of the fuel supply system authorized by the timer, any blockage or delay in this system results in an overdose of fuel towards the combustion chamber, which, in addition to emptying the tank, can disrupt the operation of the tool. Summary of the invention

[0005] The invention aims to overcome at least some of the aforementioned drawbacks and to offer a fuel dosing system capable of combining the advantages of simplicity and reliability for its implementation.

[0006] The invention therefore relates to a fuel dosing system for a fastening tool such as a nail gun comprising a dosing box configured to allow the passage of a predetermined dose of fuel from a fuel reservoir and to a combustion chamber of the tool during a single activation of the tool.

[0007] Preferably, the system includes a dosing unit enabling the dosing to be activated by an internal drawer and by a first inlet chamber delimited between the drawer and said dosing unit, and an outlet chamber, the internal drawer having at least one filling position in which the first inlet chamber is fluidly connected to the reservoir so as to be able to be filled with fluid during the fluid connection while the outlet chamber is fluidly disconnected from the combustion chamber of the tool, and an emptying position in which, conversely, the first inlet chamber is fluidly disconnected from the reservoir and the outlet chamber is fluidly connected to the combustion chamber.

[0008] In the first embodiment, the system may further include a second inlet chamber with a different volume than the first inlet chamber, allowing a second dose to be provided that is different from the first dose in the first inlet chamber when the system is in the filling position.

[0009] Advantageously, the movement of the drawer in the case is electrically activated by means of an electrical control signal emitted by a controller module.

[0010] For example, the drawer is linked to an electromagnet configured to be able to push or pull the case towards either of the two filling positions.

[0011] Advantageously, the system includes a solenoid valve, a solenoid and / or at least one elastic return element to hold the drawer in position in the housing, so that the emptying position corresponds to a release position of the system.

[0012] In a second embodiment, the fuel metering from the tank to the combustion chamber can be carried out in a metering box of the tool in which a screening is carried out by a cavity disc placed between an inlet and an outlet of said metering box and driven in rotation during a time pulse corresponding to a passage of the cavity disc between an angular position of fuel filling of the cavities from the inlet of the box and a position of fuel emptying of the cavities towards the outlet of the box, the filling of the cavities corresponding to a predefined metering.

[0013] The system may further provide that, in the first or second embodiment, the dosage is adjusted by a number of electrical pulses activating the dosing system.

[0014] Preferably, the fastening tool is a nail gun.

[0015] The invention also relates to a fastening tool comprising the fuel dosing system.

[0016] Advantageously, the dosing system further includes a cavity disc placed between an inlet of the housing and an outlet of the housing, in which the passage of said predetermined dose of fuel from the tank to the combustion chamber of the tool is carried out by means of screening by said cavity disc.

[0017] Advantageously, the dosing system includes a cavity disc configured to be driven in rotation for a time interval corresponding to a displacement of the cavity disc between an angular position of fuel filling of the cavities of the cavity disc from the inlet of the casing and a position of fuel emptying of the cavities towards the outlet of the casing, the filling of the cavities corresponding to a predefined dosing.

[0018] Advantageously, the dosing system further includes one or more additional screening discs placed in a sealed manner downstream of the cavity disc in order to ensure the obstruction or opening of the cavities of the cavity disc to respectively allow or prevent the passage of a predefined dose of fuel towards the outlet of the casing.

[0019] Advantageously, the dosing system includes contact surfaces between discs provided with means of sealing between them and with the housing so as to prevent leaks during the operation of the system.

[0020] Advantageously, the dosing system includes a cavity disc which is driven by a user, when the tool is actuation, by means of a drive mechanism such as a gear.

[0021] Advantageously, the dosing system is configured to be adjusted by one or more electrical pulses.

[0022] Advantageously, the metering system includes one or more electrical pulses configured to actuate the metering system a predetermined number of times to supply a predetermined amount of fuel into the combustion chamber.

[0023] The invention also relates to a fixing tool comprising a dosing system as previously described.

[0024] Advantageously, the fastening tool is a nail gun. Brief description of the figures

[0025] The invention will be better understood upon a detailed study of two embodiments taken by way of non-limiting examples and illustrated by the accompanying drawings, in which: There Figure 1 schematically represents the tool's architecture. Figure 2 represents the dosing system according to a first embodiment, with drawers. Figure 3 and the Figure 4 represent the dosing system according to a second embodiment, with a disc. Detailed description of the invention

[0026] There Figure 1 schematically represents the fastening tool as a whole, with a reservoir 2 for storing fuel, and a combustion chamber 4 in which fuel combustion takes place during tool operation, to actuate a piston or cylinder 5 in order to trigger the tool, for example to eject a nail, a staple, a punch...

[0027] The dosing system 1 of the invention is placed between the fuel tank 2 and the combustion chamber 4 to which it is fluidly connected upstream and downstream respectively by its inlet 7 and by its outlet 8.

[0028] The fuel used is in a fluid state in the tank, for example stored as a gas such as liquefied petroleum gas, known by the acronym "LPG", or any other liquid or gaseous fuel.

[0029] In all embodiments, the fuel metering system 1 for the fastening tool is configured to allow the passage of a predetermined dose of fuel from a fuel reservoir 2 to the combustion chamber 4 of the tool during a single activation of the tool.

[0030] It therefore serves as a volumetric valve to meter this fuel, and constitutes a mechanism which makes it possible to avoid continuous fuel leaks in the event of failure, since the fuel is not injected by the continuous opening of a valve for a given time which may be prolonged undesirably, but is injected by dose in one go at each pulse of the planned electrical control signal 6.

[0031] In the first embodiment illustrated in Figure 2, system 1 includes a dosing box 3 allowing the dosing to be activated by an internal drawer 10 which is linked in translation in the box 3 and in sealed connection with it in a casing 16, for the fuel concerned.

[0032] The drawer dosing system 10 includes a first inlet chamber 13 delimited between the drawer 10 and said dosing box 3, and an outlet chamber 14.

[0033] The internal drawer 10 has at least one filling position in which the first inlet chamber is fluidly connected to the reservoir 2 so that it can be filled with fluid during the fluid connection while the outlet chamber 14 is fluidly disconnected from the combustion chamber 4 of the tool.

[0034] The internal drawer 10 also has an emptying position in which, contrary to the filling position, the first inlet chamber 13 is fluidly disconnected from the tank 2 and the outlet chamber 14 is fluidly connected to the combustion chamber via at least one outlet 11,12 of the chambers 13,14 and then the outlet 8 of the housing 3.

[0035] Thus, in the filling position, the pressurized fuel flows from the tank to the inlet of the dosing box, can enter via an inlet 7.9 of the box 3 and fill the first inlet chamber, which corresponds to a predetermined fuel dosage to be used in the combustion chamber, depending on the desired tool power, its low or high operating temperature range, and the fuel used.

[0036] Thus, when using, for example, a fuel with a so-called wide flammability range, i.e., for example, a lower flammability limit of five percent in air and an upper flammability limit of seventy-five percent, two ejection powers can be provided thanks to this dosing system 1.

[0037] In the first embodiment, the system 1 may further include a second filling chamber 14 of a different volume than the first inlet chamber, allowing a second dosage different from the first dosage to be provided in the inlet chamber when the system is in the filling position.

[0038] The system then has two filling positions, to selectively fill either the first filling chamber or the second filling chamber.

[0039] As illustrated by the Figure 2The selection of the first or second filling chamber is, for example, carried out according to the direction of actuation of the sliding of the drawer in the housing, downstream, i.e. towards the tank, to position the inlet of the housing opposite the first filling chamber, so as to connect this chamber fluidly with the tank, or upstream, i.e. towards the combustion chamber, so as to put the inlet of the housing opposite the second filling chamber and to connect them fluidly.

[0040] We then have a first filling position and a second filling position, which allows us to plan two distinct fuel dosages, and thus to create a tool capable of being used in two modes, to distinguish for example two temperature ranges of use or two power levels of use.

[0041] The user can thus adapt the tool to the environment of use, the fuel chosen in the tool, and the materials on which he applies the tool.

[0042] Advantageously, the movement of the drawer in the case is electrically activated by means of an electrical control signal emitted by a controller module.

[0043] This allows for titrations to be carried out using reduced doses applied several times according to a predefined frequency signal.

[0044] In the event of failure, and unlike prior art tool systems, this dosing system prevents any propagation of fuel from the tank and downstream of said dosing system, in particular towards the combustion chamber, since the fuel-tight drawer relative to the casing forms an obstacle to its propagation towards the casing outlet, whether there is a blockage in the filling position or in the emptying position.

[0045] For example, the drawer is linked to an electromagnet configured to be able to push or pull the case towards either of the two filling positions.

[0046] This type of linear actuator allows bidirectional actuation of the drawer.

[0047] The solenoid is placed around the housing, and the electromagnet is on the upstream side of the drawer, namely closer to the tank than to the combustion chamber, so as to free the latter from any obstruction.

[0048] Alternatively, we can use a plurality of solenoids, for example two, operating in opposition, one for pushing and the other for pulling the spool.

[0049] Advantageously, the system includes a solenoid valve, a solenoid and / or at least one elastic return element to hold the drawer in position in the housing, so that the emptying position corresponds to a release position of the device.

[0050] Thus, the fuel from the tank only enters the housing and the first or second inlet chamber when the tool is activated, corresponding to sending a control signal from the dosing system to move the drawer to the filling position, then back to the emptying position, which sends the predefined dose of fuel into the combustion chamber, and avoids any additional movement of fuel or the drawer from the moment the fuel is in the combustion chamber.

[0051] The system then has two possible actuations corresponding to two opposite directions of movement of the drawer, for example according to a positive pulse or according to a negative pulse electrical control signal emitted by the controller module.

[0052] This makes the tool safer by avoiding any additional actuation once the fuel has been sent into the combustion chamber from the emptying position, since this corresponds to the neutral position of the tool.

[0053] In a second embodiment illustrated by the Figures 3 And 4 , it can be foreseen that the fuel metering from the tank to the combustion chamber is done in a metering box of the tool in which a screening is carried out by a cavity disc 17.

[0054] Such a cavity disc is placed between an inlet and an outlet of the dosing unit and is free to rotate about an axis of the unit, and is in a sealed connection with said unit.

[0055] The cavity disc is configured to be able to be driven in rotation during a time pulse corresponding to a passage of the cavity disc between an angular position of fuel filling of the cavities from the inlet of the casing and a position of fuel emptying of the cavities 18 towards the outlet of the casing, the filling of the cavities corresponding to a predefined volume for dosing.

[0056] For example, it is possible to provide that the cavity disc 17 is coupled with a complementary screening disc or several screening discs 20,21 located directly behind it in a sealed connection and allows the cavities to be blocked or opened to allow or prevent the passage of a predefined dose of fuel between the upstream and downstream of these discs.

[0057] The screening disc is the disc 20 containing the cavities 18 and several complementary discs 17, 21, respectively the inlet disc 17 containing an inlet orifice and the outlet disc 21 containing an outlet orifice, are fixed in the system 1, while the disc 20 is rotating, which allows one of its cavities 18 to coincide alternately with the inlet orifice of the fixed disc 17, then with the outlet orifice of the fixed disc 21, so as to achieve a metering of fuel from and to the outlet of the housing 3 which is activatable and which cannot be locked in the position of continuous discharge of fuel between the tank 2 and the combustion chamber 4, as in the first embodiment.

[0058] In this second embodiment, the contact surfaces between the discs 17, 20 and 21 are provided with sealing means between themselves and with the housing 3, preventing leaks during all phases of operation of the system 1.

[0059] The cavity disc is, for example, driven in rotation electrically or manually by the user when the tool is operated, for example by a drive mechanism 19 which may be geared.

[0060] System 1 may further provide that, in the first or second embodiment, the dosing is adjusted by a number of electrical pulses actuating the dosing system a predefined number of times to supply a predefined quantity of fuel into the combustion chamber.

[0061] The invention also relates to a fastening tool comprising the fuel dosing system 1.

[0062] Preferably, the fastening tool is a nail gun.

[0063] This provides a fixing tool with a dosing system that allows the fuel dose to be measured in the combustion chamber in a chamber or in cavities, with a predefined volume temporarily stored in a moving part which is sent to the combustion chamber when the elements of the dosing system are aligned towards the emptying position under the impulse of an electrical control signal, which can provide the tool with two modes of operation.

Claims

1. Fuel metering system (1) for a fastening tool such as a nail gun, said system (1) comprising a fuel reservoir (2) and a metering box (3) configured to be filled from the fuel reservoir with a predetermined dose of fuel and to permit, on a single activation of the tool, the passage of said predetermined dose of fuel to a combustion chamber (4) of the tool.

2. Dosing system according to claim 1, in which the dosing housing (3) has an internal drawer (10) movable in translation within said housing (3) for carrying out the dosing of fuel, said drawer (10) having a first inlet chamber (13) delimited between the drawer (10) and said dosing housing (3) for storing the dose, and an outlet chamber (14), the internal drawer (10) having at least one filling position in which the first inlet chamber (13) is fluidly connected to the reservoir (2) so as to be able to be filled with fluid during the fluid connection while the outlet chamber (14) is fluidly disconnected from the combustion chamber (4), and an emptying position in which, conversely, the first inlet chamber (13) is fluidly disconnected from the reservoir and the outlet chamber (14) is fluidly connected to the combustion chamber (4).

3. Dosing system (1) according to any one of claims 1 and 2, further comprising a second inlet chamber of a different volume from the first inlet chamber, enabling a second dosage to be provided that is different from the first dosage from the first inlet chamber when the system is in the filling position.

4. Dosing system (1) according to any one of claims 1 to 3, configured to allow electrical activation of the movement of the drawer in the housing (3) by means of an electrical control signal emitted by a controller module.

5. Dosing system (1) according to any one of claims 3 and 4, wherein the drawer is linked to an electromagnet (15) configured to be able to push or pull the housing (3) towards either of the two filling positions.

6. Dosing system (1) according to any one of claims 1 to 5, wherein the system (1) comprises a solenoid valve, a solenoid and / or at least one elastic return element to hold the spool (10) in position in the housing (3), so that the emptying position corresponds to a release position of the system (1).

7. Dosing system (1) according to claim 1, further comprising a cavity disc (17) placed between an inlet of the housing (3) and an outlet of the housing (3), in which the passage of said predetermined dose of fuel from the reservoir (2) to the combustion chamber (4) of the tool is carried out by means of screening by said cavity disc (17).

8. Dosing system (1) according to claim 7, wherein the cavity disc (17) is configured to be driven in rotation for a time interval corresponding to a displacement of the cavity disc (17) between an angular position of fuel filling of the cavities (18) of the cavity disc (17) from the inlet of the casing (3) and a position of fuel emptying of the cavities (18) towards the outlet of the casing (3), the filling of the cavities (18) corresponding to a predefined dosage.

9. Dosing system (1) according to claim 8, further comprising one or more additional screening discs (20, 21) placed in a sealed manner downstream of the cavity disc (17) in order to ensure the obstruction or opening of the cavities of the cavity disc (17) to respectively allow or prevent the passage of a predefined dose of fuel towards the outlet of the casing.

10. Dosing system (1) according to claim 9, wherein the contact surfaces between discs (17, 20, 21) are provided with sealing means between them and with the housing (3) so as to prevent leaks during the operation of the system (1).

11. Dosing system (1) according to any one of claims 7 to 10, wherein the cavity disc (17) is driven by a user, when the tool is actuation, by means of a drive mechanism (19) such as a gear.

12. Dosing system (1) according to any one of the preceding claims, said dosing system being configured to be adjusted by one or more electrical pulses.

13. Dosing system (1) according to claim 10, wherein said one or more electrical pulses are configured to actuate the dosing system a predetermined number of times to supply a predetermined amount of fuel into the combustion chamber.

14. Fixing tool comprising the dosing system according to any one of the preceding claims.

15. Fastening tool according to claim 14, wherein the fastening tool is a nail gun.

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