EP2650087A2 - Setting tool - Google Patents

Abstract

The tool has a fuel tank (5) storing a fuel i.e. liquefied gas, and a combustion chamber (2) connected to the tank. A piston (10) is moved in a cylinder (11) for driving a driving plunger (12), and an exhaust gas opening (17) ejects exhaust gases after an ignition of a fuel/air mixture. A gas pressure course of the combustion chamber is selectively reducible compared to a maximum pressure course to affect a driving energy of the piston through the ejection. The maximum pressure course is applied over a segment of travel of the piston after the ignition in the case of a reduced driving energy.

Description

The invention relates to a tacker, in particular a hand-held tacker, according to the preamble of claim 1.

DE 40 10 517 A1 describes a gas powered tacker with a combustion chamber, a piston guided in a cylinder, and a manually adjustable exhaust port in the combustion chamber to reduce drive-in energy. When the exhaust gas opening is set to a partially or maximally opened position, part of the combustion gases escapes through the exhaust gas opening immediately after the beginning of a pressure buildup after ignition of a gas mixture.

It is the object of the invention to provide a tacker having a variable drive-in energy.

This object is achieved according to the invention for a drive-in device mentioned above with the characterizing features of claim 1. As a result of the maximum pressure applied initially over the first path section, the piston experiences a high initial acceleration and a defined minimum speed.

As a result, inter alia, penetration of the nail or to be placed connecting means in the surface area of a workpiece (wall, ceiling, wooden beams, etc.) is ensured. For this first section of penetration, a high velocity of the piston is desired. Apart from a high starting speed, it may then be desirable to provide a maximum or reduced driving energy depending on the required penetration depth (nail length, etc.) and / or material quality of the workpiece (wood, brick, cement, concrete, etc.).

Under the maximum pressure curve in the context of the invention, therefore, the time course of the combustion chamber pressure and thus the force acting on the piston driving force is to be understood, which abuts reducing measures without the Eintreibenergie. This does not preclude, depending on the requirements and the type of construction, that even when the maximum driving energy is selected, a desired gas pressure loss, e.g. is present over an exhaust port.

In the sense of the invention, the gas pressure profile when selecting a reduced driving energy differs from the maximum pressure profile in that it substantially corresponds to the maximum pressure profile in the first path section and drops later than the maximum pressure curve, ie in the further course of the piston movement.

The size of the first path portion of the piston can be selected according to requirements. Preferably, it may be at least 10%, more preferably at least 20% of the total piston travel.

It is generally understood that the reduction of the gas pressure may be through one or more exhaust ports. The measures provided according to the preferred embodiments can generally be applied to exactly one and / or several and / or all exhaust ports.

In a generally advantageous embodiment of the invention, it is provided that the at least one exhaust gas opening is arranged in the region of the cylinder. Preferably, the piston releases the exhaust opening only after the first path section. As a result, it is ensured in a structurally simple manner that the piston initially experiences an undiminished acceleration. In a particularly simple and inexpensive design, the exhaust gas opening arranged in the region of the cylinder can be selectably changed between two states of the opening, for example open / closed. Such a selection can also be done, for example, by a manual mechanical adjustment.

In an alternative or supplementary embodiment, the exhaust gas opening may also be arranged in the region of the combustion chamber. This may be the case, in particular, when a defined delayed release of the exhaust gas opening takes place. In general, exhaust gas openings can also be provided both in the region of the cylinder and in the region of the combustion chamber. There may also be a different type of control of such multiple exhaust ports.

In principle, the release of an exhaust gas opening in the sense of the invention can be triggered by a defined time delay and / or by a spatial position, in particular of the piston.

In a generally advantageous embodiment, the exhaust gas outlet is formed controllable closable. As a result, the selection of the drive-in energy can generally be connected to an electronic control unit of the device. In particular, this makes it possible that a release of the at least one exhaust port to reduce the driving energy after a defined time delay after the ignition of the fuel-air mixture takes place. This can be realized for example by an electrical switching valve. Preferably, the time delay is predetermined by the controller. Particularly preferably, the time delay is calculated by the controller, for example based on a desired driving energy, wherein the time delay is particularly greater, the greater the desired driving energy, so that the less the drive-in energy is to be reduced, the longer the maximum pressure curve is maintained ,

In a preferred development of the invention, in the interest of a precise selection of the driving energy, an effective cross section of the at least one exhaust gas opening can be variably changed, in particular over a plurality of discrete stages or continuously. This also includes embodiments in which, for example, there are a plurality of exhaust gas openings, each of which is individually closable.

In general, an adjustment of the driving-in energy can take place by means of a mechanical actuating unit. According to an advantageous embodiment, an adjustment of the driving energy can also be done by means of an electronic control unit. In a preferred detailed design, a sensor element can determine an operating condition for the preferably automatic adjustment of the driving-in energy. Such a sensor member may ideally detect the nature of the material of the workpiece. However, it can also be a sensor member which determines, for example, the type of charged nails of the tacker, for example with respect to a length of the nails or other condition. Further advantageous is an adjustment of the driving energy via a display unit, preferably an electronic display unit, controllable, whereby incorrect settings is prevented.

Fig. 1

zeigt eine schematische Ansicht einer ersten Ausführungsform eines erfindungsgemäßen Eintreibgerätes.

Fig. 2

zeigt eine zweite Ausführungsform der Erfindung.

Fig. 3

zeigt eine dritte Ausführungsform der Erfindung.

Fig. 4

zeigt eine vierte Ausführungsform der Erfindung.

Fig. 5

zeigt ein Detail der Ausführung nach Fig. 4 mit einer teilweise geöffneten Abgasöffnung.

Fig. 6

zeigt das Detail aus Fig. 5 mit vollständig geöffneter Abgasöffnung.

Fig. 7

zeigt eine Abwandlung des Details aus Fig. 5.

Further features and advantages of the invention will become apparent from the embodiments and from the dependent claims. Hereinafter, several preferred embodiments of the invention will be described and explained in more detail with reference to the accompanying drawings.

Fig. 1

shows a schematic view of a first embodiment of a tacker according to the invention.

Fig. 2

shows a second embodiment of the invention.

Fig. 3

shows a third embodiment of the invention.

Fig. 4

shows a fourth embodiment of the invention.

Fig. 5

shows a detail of the execution Fig. 4 with a partially open exhaust port.

Fig. 6

shows the detail Fig. 5 with fully open exhaust port.

Fig. 7

shows a variation of the detail Fig. 5 ,

This in Fig. 1 schematically shown tacking device comprises a housing 1, in which a combustion chamber 2 is arranged. Liquefied gas is stored as fuel in a fuel tank 5 and can be injected via a line 3 into the combustion chamber 2. The line 3 connects a metering device 4 with the combustion chamber 2, wherein the metering device 4 in turn is connected to the fuel tank 5 arranged in or on the housing 1. The fuel tank can be designed in particular as a replaceable cartridge.

The tacker additionally comprises an electronic control 6 with an electric accumulator 6a as an energy store. About the electronic control 6, a spark plug 7 is driven in the combustion chamber 2 by means of a line 7a. Furthermore, if necessary, the metering device 4 is actuated, provided that it has electrical valves or other electrically controlled components. In a front area of the A driver is a magazine 8 for storing fasteners, such as nails, arranged. A pressing member 9 can be pressed against a workpiece to release a triggering of the tacker.

The driving of a fastening member from the magazine 8 via the ignition of a liquid-air mixture in the combustion chamber 2 by means of the spark plug 7, after which a piston 10 is driven in a cylinder 11 continuously forward and a driving ram 12, the fastening member or the Drives nail into the workpiece. This driving operation is triggered by an operator via a switch 13, which is presently arranged in a grip region 14 of the housing 1. The path of the piston 10 is limited by an elastic stop or buffer 15. Prior to ignition, the mixture is distributed in a known manner with the assistance of an electrically driven fan 16 in the combustion chamber.

A metering of the fuel by means of the metering device 4 can take place, for example, depending on the air pressure (altitude) or other criteria. As a result, a possible influence on a driving-in energy to a certain extent can be carried out as required in addition or independently of the influencing described below.

On the cylinder 11, a first exhaust gas opening 17 is provided in a front region, by means of which a driving-in energy of the piston 10 is selectably changeable. A second exhaust port 18 is arranged in a rear region relative to the piston path. The second exhaust port 18 serves primarily to eject or purge the combustion gases after the drive has taken place.

In contrast, the first exhaust gas opening 17 is arranged a little behind the combustion chamber 2, which is delimited by the piston in an initial position of the piston 10 (the present illustration is purely schematic and not to scale). First, the passage from the combustion chamber to the exhaust port 17 is blocked by the piston 10. Only after the piston has covered a first path section under full gas pressure, the combustion gas can escape through the exhaust port 17, provided that it is open. Such an opening may be manually selectable. Depending on the requirements, a simple setting of "on" (reduced drive-in energy) or "to" (maximum drive-in energy) may be present. It can also be an adjustable change of the Cross section act, for example by means of an adjustable valve in a design according to DE 40 10 517 A1 ,

By contrast, when the exhaust gas opening 17 is closed, the maximum possible gas pressure prevails over the entire piston travel (maximum pressure progression), so that a maximum driving energy is also achieved.

Fig. 2 shows a second embodiment of the invention in which both exhaust ports 17, 18 are selectably closed by means of controllable actuators 19. For this purpose, lead control lines 20 of the control unit 6 to the actuators 19. The first exhaust port 17 can thereby automated according to the manual case after Fig. 1 be operated. Alternatively or additionally, however, an exact timing of the exhaust gas opening may also be present, for example an opening which is delayed with respect to the ignition time. In such a control, the exhaust port 17 may be arranged in principle in the region of the combustion chamber 2.

Fig. 3 shows a further embodiment in which only one controllable exhaust port 17 is present. This is schematically provided with a rotatably mounted closure flap 21, which is held in a closed position via a hook-shaped latch 22. The latch is controllably movable via an actuator, so that the flap 21 can be released as needed to reduce the driving energy. Similar to the example Fig. 1 Blocked the piston in a first path section, the passage of the gases from the combustion chamber 2 to the exhaust port 17th

The flap 21 may, for example, be spring loaded in the closing direction, so that it returns to the closed position at a sufficiently low gas pressure. Subsequently, it acts as a check valve, so that the cooling residual gases provide a negative pressure in the combustion chamber, by means of which the piston 10 is returned to the starting position. This is generally the preferred principle of piston return. Alternatively or additionally, however, a return spring can also be provided.

Fig. 4 to Fig. 6 show a further embodiment of the invention, according to the Fig. 3 is similar. Unlike the flap after Fig. 3 here is a continuously variable valve spool 23 above the exhaust port 17. By adjusting an effective cross section of the exhaust port is changed, so that the driving energy exactly is adjustable. The slider 23 is controllably linearly displaceable via an actuator, not shown. Fig. 4 to Fig. 6 show various positions of the valve spool 23, namely closed, semi-open and open.

In the modification to Fig. 7 is in addition to the valve spool Fig. 4 to Fig. 6 a flap 24 above the exhaust port through which a check valve is formed. This allows a simple reset of the piston 10 as in the previous example, without a correspondingly fast provision of the valve spool 24 must be made.

It is understood that the individual features of the various embodiments can be usefully combined depending on the requirements.

Claims (12)

A tacker comprising
a tank (5) for storing a fuel, in particular LPG,
a combustion chamber (2) connected to the tank (5),
a in a cylinder (11) movable piston (10) for driving a driving ram (12), and
at least one exhaust port (17) for discharging exhaust gases after ignition of a fuel-air mixture,
wherein a gas pressure profile of the combustion chamber (2) for influencing a driving-in energy of the piston (10) can be selectively reduced by the discharge in relation to a maximum pressure variation,
characterized,
that is applied in the case of a reduced driving energy of the maximum pressure curve after ignition of a first path section of the piston (10). A tacker according to claim 1, characterized in that the exhaust port is arranged in the region of the cylinder, wherein in particular the piston releases the exhaust port only after the first path section. A tacker according to claim 1, characterized in that the exhaust port (17) in the region of the combustion chamber (2) is arranged. A tacker according to one of the preceding claims, characterized in that the exhaust gas opening (17) can be controlled by a particular electronic control controllable. A tacker according to claim 4, characterized in that a release of the at least one exhaust port (17) for reducing the driving energy after a defined time delay after the ignition of the fuel-air mixture. A tacker according to claim 5, characterized in that the time delay is predetermined by the controller. A tacker according to claim 6, characterized in that the time delay is calculated by the controller, in particular based on a desired driving energy. A tacker according to any one of claims 4 to 7, characterized in that an effective cross-section of the at least one exhaust port (17) is adjustably changeable, in particular over a plurality of discrete stages or continuously. A tacker according to any one of claims 4 to 8, characterized in that an adjustment of the driving energy is effected by means of a mechanical actuator. A tacker according to any one of claims 4 to 9, characterized in that an adjustment of the driving energy by means of an electronic control unit (6). A tacker according to claim 10, characterized in that a sensor member determines an operating condition for the particular automatic adjustment of the driving energy. A tacker according to one of the preceding claims, characterized in that an adjustment of the driving energy via a display unit, in particular an electronic display unit, is controllable.

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