Setting tool assembly, setting tool, and metering head for the setting tool

Abstract

A setting tool assembly for driving fastening elements in constructional components includes a combustion energy-operated setting tool (10), a fuel source (11), a metering head (20) for metering a predetermined amount of liquid fuel or gaseous fuel stored in the fuel source (11) into the combustion chamber (12) of the setting tool (10), the metering head (20) having an inlet (23) communicating with the fuel source (11), at least two outlets (42, 52, 62, 72), and at least two metering valves (40, 50, 60, 70) which connect the inlet (23) with respective outlets and which have different volumes of metering chambers (41, 51, 61, 71), and a device for selectively connecting the outlets of the metering head (20) with the combustion chamber (12).

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a setting tool assembly for driving fastening elements in constructional components and including a combustion energy-operated setting tool having at least one combustion chamber, a fuel source, a metering head for metering a predetermined amount of liquid fuel or gaseous fuel stored in the fuel source into the at least one combustion chamber of the setting tool, with the metering head having at least one inlet communicating with the fuel source, at least two outlets, and at least two metering valves connected with the at least one inlet and respective outlets and having different volumes of their metering chambers.

[0003] 2. Description of the Prior Art

[0004] The setting tool of setting tool assemblies of the type described above can be driven with liquid or gaseous fuels which are combusted in a combustion chamber of the setting tool in form of a mixture with an oxidant (e.g., air), with combustion energy driving the drive piston that drives a fastening element in a constructional component. The metering of fuel is effected, e.g., with a metering head having at least one metering valve with at least one metering chamber.

[0005] The drive energy, which is used for driving the fastening element, directly depends on the chemically bonded energy introduced into the combustion chamber of the setting tool and on possibility to convert it into kinetic energy. The problem consists in admixing to the fuel, for each operational cycle, an appropriate amount of the oxidant, air or oxygen. The fuel-air ratio λ is retained, in an ideal case, constant and has a value of λ=1.

[0006] The amount of oxygen, which is available for combustion, strongly depends on the outside temperature, air pressure, and air humidity. Therefore, the amount of fuel varies significantly with changes in the above-mentioned parameters, up to 40% in extreme cases.

[0007] German Publication DE 19950350 A1 discloses a metering head which is pinned on a union for metering of a metered amount of a liquified fuel gas in different combustion chambers of a setting tool. The metering head has an inlet, at least two outlets, and two or more metering valves which connect the inlet with respective outlets. The metering valves can have metering chambers having different volumes. Each metering valve supplies with fuel a different chamber of the setting tool. The fuel is metered via appropriate metering chambers associated with respective combustion chambers. The drawback of the described metering head consists in that it is not possible to adapt the fuel volume for a particular chamber to particular environmental conditions. The resulting change of λ at changing environmental conditions leads to change of the setting energy at delivery of a constant amount of fuel.

[0008] German Publication DE 4243 617 A1 discloses a setting tool in which for an operational cycle, a gas inlet valve is mechanically opened, and fuel is fed from a fuel source into an intermediate chamber that is connected with the environment. The connection of the intermediate chamber with the environment permits to equalize the pressure and, if needed, the temperature with the surrounding air, whereby an adaptable air-fuel mixture is fed into a combustion chamber. The fuel is fed from the intermediate chamber to the combustion chamber at a predetermined time. The drawback of this solution consists in high technical expanses associated with maintaining of the air-fuel ratio λ which, in turn, is associated with high manufacturing costs.

[0009] European Publication EP 0 597 241 B1 discloses a setting tool in which fuel for admixing is delivered from a fuel source to the combustion chamber via a normally-closed solenoid-actuated valve. The actuation is effected electronically by a switching circuit in response to actuation of a switch, with the valve opening after a predetermined time period for enabling flow from the fuel source into the combustion chamber. There, likewise the drawback consists in high technical expenses, which are associated with maintaining of the air-fuel ratio λ, and the resulting high manufacturing costs.

[0010] Accordingly, an object of the present invention is to provide a setting tool assembly of a type described above in which the drawbacks of the prior art setting tools and assemblies are eliminated.

[0011] Another object of the present invention is to provide a setting tool assembly of a type described above which would enable an easy adaptation of the fuel metering.

SUMMARY OF THE INVENTION

[0012] These and other objects of the present invention, which will become apparent hereinafter are achieved by providing a device for selectively connecting the two outlets of the two metering valves with the at least one combustion chamber.

[0013] According to the invention, there is provided a setting tool assembly that in addition to the setting tool and a metering head, includes a device for selectively connecting outlets of the metering valves of the metering head with the combustion chamber. The provision of the selectively connecting device permits to activate predetermined metering chambers or the metering chamber-containing valves so that upon actuation of the metering head, the fuel contained in these metering chambers flows in the combustion chamber or chambers. In this Way, at low temperatures those metering valves are connected with the combustion chamber which have a relatively large metering chamber volume, to provide for a relatively rich air-fuel mixture in the combustion chamber. When the setting tool becomes heated after performing several setting processes, the device permits to associate another set of metering valves of the metering head with the combustion chamber(s), the set of metering valves having a smaller volume metering chambers to provide a less rich air-fuel mixture in the combustion chamber(s). The device for selectively connecting sets of metering valves having metering chambers with different volumes with the combustion chamber, permits to technically easy change the fuel-air ratio in the combustion chamber(s).

[0014] Advantageously, the selectively connecting device has an operational member associated with at least one of metering head and the combustion chamber and having fuel passages with stops for supporting at least one of the at least two outlets of the metering head and blind bores for receiving another one of the at least two outlets without actuating, respective metering valves. The selectively connecting device is displaceable between different indexing positions in which respective ones of the fuel passages and the blind bores are associated with each of the at least two metering valves.

[0015] The operational member permits to easily activate those metering valves or their outlets that are associated with the fuel passages, and to keep inactive those metering valves or their outlets that are associated with the blind bores.

[0016] According to an advantageous embodiment of the present invention, for each indexing position of the selectively connecting device, a number of fuel passages and blind bores, which corresponds to a respective indexing position, is operationally associated with the metering valves. This measure permits to activate and de-activate one or several metering valves and, thereby, to be able to obtain a large number of possible combination of metering valves for metering fuel in the combustion chamber(s).

[0017] Advantageously, the operational member is formed as a slide displaceably supported on a combustion chamber wall for displacement, relative to the outlets, from one indexing position of the selectively connecting device to its another indexing position. The slide can be arranged either on the setting tool or on the metering head. The formation of the operational member as a slide provides for a simple and cost-effective formation of the selectively connecting device.

[0018] When the operational member is formed as an integral part of the combustion chamber wall, the metering head with the metering valves is displaceably arranged opposite the operational member. This arrangement also can be easily executed.

[0019] For metering a predetermined volume, the metering head can be displaced by an actuation device from its off-position in which the metering head is spaced from the member and the metering valves are closed, to its operational position in which the outlets extend into respective fuel passage(s) and blind bore(s) in a predetermined indexing position of the selectively connecting device, with the metering valve(s), the outlet of which extend into the fuel passage(s) being activated. The foregoing measures permit, by using the selectively connecting device, to select the to-be-activated metering valves and to activate the selected metering head with the actuation device.

[0020] Advantageously, the metering valves are arranged on the metering head in a row, with the fuel passages and the blind bores being likewise arranged in a row located opposite the row of metering valves.

[0021] Advantageously, there is provided an electromechanical device for displacing the member or the metering head from one indexing position into another indexing position. The use of the electromechanical device facilitates handling of the setting tool assembly and the setting tool itself, as the user does not need anymore to manually adjust the selectively connecting device. Rather, with a control device that controls the operation of the electromechanical device, it is possible, by displacing the selectively connecting device or the metering head, to select the to-be-activated metering valves dependent on measured pressure and temperature of the surrounding air and/or of the combustion chamber.

[0022] According to a further development of the present invention, the metering head itself can be provided with the device for connected the outlets of the metering valves with the combustion chamber of the setting tool. The metering head, which is usually pinned on a fuel container, can be easily removed from the setting tool, together with the fuel container, which provides for an easy monitoring of the selectively connecting device. In case of malfunction, the selectively connecting device can be easily removed and repaired or replaced.

[0023] The novel features of the present invention, which are considered as characteristics for the invention, are set forth in the appended claims. The invention itself, however both as to its construction and its mode operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawing show:

[0025] FIG. 1 a longitudinal cross-sectional view of a setting tool assembly including a setting tool, a fuel container, a metering head, and a device for selectively connecting the metering head with the setting tool in an off-position of the setting tool and a first indexing position of the selectively connecting device;

[0026] FIG. 2 a cross-sectional view of a portion of the setting tool assembly shown in FIG. 1 at an increased, in comparison with FIG. 1 scale, in a press-on-position of the setting tool and in the first indexing position of the selectively connecting device;

[0027] FIG. 3 a cross-sectional view similar to that of FIG. 2 but in a second indexing position;

[0028] FIG. 4 a cross-sectional view of another embodiment of a setting tool assembly including a setting tool, a fuel container, a metering head, and a device for selectively connecting the metering: head with the setting tool in an off-position of the setting tool and in a first indexing position of the selectively connecting device;

[0029] FIG. 5 a cross-sectional view of a further embodiment of a setting tool assembly including a setting tool, a fuel container, a metering head, and a device for selectively connecting the metering head with the setting tool in an off-position of the setting tool and in a first indexing position of the selectively connecting device.

[0030] FIG. 6 a cross-sectional view of a portion of the setting tool assembly shown in FIG. 5 at an increased, in comparison with FIG. 1 scale, in a press-on position of the setting tool and in the first indexing position of the selectively connecting device; and

[0031] FIG. 7 a cross-sectional view similar to that of FIG. 6 but in a second indexing position of the selectively connecting device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] FIGS. 1 through 3 show a first embodiment of a setting tool assembly according to the present invention and including a setting tool 10, shown in a very simplified manner, a metering head 20, a fuel container 11, and a device 25 for selectively connecting the metering head 20 with the setting tool 10. In FIG. 1, the inventive setting tool assembly is shown in its initial or off-position and in FIGS. 2-3 the setting tool assembly is shown in its operational position.

[0033] In the embodiment of the setting tool assembly shown in FIGS. 1-3, the setting tool 10 is driven by a fuel gas. The setting tool 10 has a housing in which a setting mechanism is located with which a fastening element (not shown) is driven in a constructional component (likewise not shown) when the setting tool 10 is pressed against the constructional component and is actuated.

[0034] The setting mechanism includes, among others, a combustion chamber 12 and a piston guide 14 in which a drive piston 13 is displaceably arranged. Usually, a bolt guide (not shown) adjoins the piston guide 14. The bolt guide receives a fastening element that can be driven in the constructional component by movable forward, setting direction end of the drive piston 13. The fastening elements can be stored in a magazine (not shown) attachable to the setting tool 10.

[0035] In the embodiment shown in the drawings, the combustion chamber 12 is formed of two sub-chambers 15 and 17 which are separated by an intermediate plate 16 displaceable in the combustion chamber 12 and provided with through-openings. With an ignition device, e.g., a spark plug, a fuel-air mixture, which fills the combustion chamber 12, can be ignited upon actuation of a trip switch (not shown).

[0036] The fuel container 11 is located, in the operational condition of the setting tool 10, in a receptacle (not shown) provided on the setting tool 10. The fuel container 11, which is shown in the drawings, is formed as a separate container that can be removed and replaced with another fuel container when the fuel in the full container is used. However, a fuel container can be permanently secured on the setting tool, forming an integral component of the setting tool. In the later case, the container can be filled with fuel a new after the fuel, which was contained therein, has been used. On the container 11, a metering head 20 is pinned. The metering head 20, which is shown in the drawings, has three metering valves 40, 60, 70 having respectively, metering chambers 41, 61, 71 of different size.

[0037] The structure of the metering valves 40, 60, 70 will be described with reference to the metering valve 40. The metering valve 40 includes a valve spool 44 that is supported by a spring 43 against a wall of the metering head 20. At the end of the valve spool 44 remote from the spring 43, there is provided a discharge pipe 45 that forms an outlet 42 of the metering valve 40. In the rear region of the discharge pipe 45, there is provided a connection channel 46 which is formed in the wall of the discharge pipe 45. The connection channel 46 connects the outlet 42 with the metering chamber 41 when the valve spool 44 is actuated and is pressed into the metering head 20 against a biasing force of the spring 43. Upon actuation of the metering valve 40 by pressing the valve spool 44 into the metering head 20, as shown in FIG. 2 (metering valves 40 and 70) and FIG. 3 (metering valves 40 and 60), the valve spool 44 simultaneously interrupts connection of the inlet 23 of the metering head 20, which connects the metering head 20 with the fuel container 11, with the metering chamber 41 (the same with the metering valve 60/70). Air, which is necessary for a combustion process in the combustion chamber 12 (or another oxidant) is described into the combustion chamber 12 or sub-chambers 15 and through separate inlets (not shown) formed therein.

[0038] A wall 18 of the combustion chamber 12, which is located opposite outlets 42, 62, 72 of the metering valves 40, 60, 70, is provided with the openings 19.1, 19.2 and 19.3 through which fuel can be delivered into the combustion chamber 12 or the subchambers 15, 17. Between the metering head 20 and the combustion chamber wall 18, there is provided a device 25 that selectively connects the outlets 42, 62, 72 of the metering head 20 with the openings 19.1, 19.2 and 19.3 in the combustion chamber wall 18. The device .25 includes, to this end, a displaceable operational member formed as a slide 30.1 that in the embodiments shown in the drawings, is arranged on the combustion chamber wall 18. The slide 30.1 is provided at one of its end with actuation means 26.1 accessible from outside of the setting tool 10 and with which the slide 30.1 can be manually displaced by the user from a position 27 (FIGS. 1, 2) in the direction of arrow 81 in a further position 28 (FIG. 3) and vice versa (in the direction of the arrow 82, FIG. 3). The slide 30.1 is held on the combustion chamber wall 18 in the positions 27, 28 by locking means 24 provided on the wall, 18 and engaging matching locking means 31 on the slide 30.1. The slide 30.1 has a row of recesses 32 a part of which forms fueled passages 33, 34, 35 which are provided with stops 39, and a part of which forms blind bores 36, 37.

[0039] In the off-position 21 of the metering head 20, none of the metering valves 40, 60, 70 is actuated, and the outlets 42, 62, 72 are spaced from the slide 30.1 so that the slide 30.1 can be displaced by a user.

[0040] In FIG. 2, the metering head 20 is displaced by an adjusting cam 91 of an actuation device 90 from its off-position 21 to its operational position 22. The actuation device 90 is provided with a rotary device for rotating the adjusting cam 91 that presses the metering head 20 against the slide 30.1. In the actuation position 22 of the metering head 20 and in the first indexing position 27 of the slide 30.1, the inlets 42 and 72 are pressed against the respective stops 39 in the full passages 33, 35. In this position of the inlets 42, 72 the metering valves 40 and 70 are actuated, and fuel can flow from the respective metering chambers 41, 71 in the associated sub-chambers 15, 17. The metering valve 60, the metering chamber 61 of which has a smaller volume than the metering chamber 71 of the metering valve 70, is not actuated, having its outlet 62 located in the blind bore 36. The indexing position 27 corresponds, e.g., to cold start position of the setting tool 10 when a rich, i.e., a fuel-rich fuel air mixture should be present in the sub-chamber 17. With appropriate marking provided on the setting tool 10 or the slide 30.1, the user can switch the setting tool 10 between cold and hot start position.

[0041] In FIG. 3, the setting tool 10 or the metering head 20 occupies an operational position 22, and the device occupies an indexing position 28 which corresponds to a hot operation of the setting tool 10 at which the sub-chamber 17 needs to be supplied with a fuel-poor fuel-air mixture. In this case, it is the outlet 62 of the metering valve 62 which is connected with the fuel passage 35. The metering valve 70 is not actuated, having its outlet extending into the blind bore 37.

[0042] A setting tool assembly shown in FIG. 4 differs from that shown in FIGS. 1-3 in that the device 25 includes an electromechanical adjusting device 80 for, the slide 30.1. With the adjusting device 80, the slide can be displaced between the indexing positions 27, 28 in accordance with the requirements and environmental conditions. The device 25 is displaced automatically in the directions 81, 82 between indexing positions 27, 28 according to a control command of a control device. In all other respects, reference is made to the previous description.

[0043] FIGS. 5-7 show a further embodiment of the device 25. In FIGS. 5-6, the device 25 is shown in its first indexing position 27, and in FIG. 7, the device 25 is shown in its second indexing position 28. In the embodiment shown in FIGS. 5-7, the operational member 30.2 remains stationary and is formed by the combustion chamber wall 18. The wall 18 has a row of recesses 32 a part of which is formed of a blind bore 37 and recesses 36, 38, and a part of which is formed as fueled passages 33, 34.

[0044] In the embodiment shown in FIGS. 5-7, the metering head 20 has four metering valves 40, 50, 60, 70 of which the metering valves 50 and 70 have a greater metering chamber volume than the metering valves 40 and 60. The metering head 20, together with the fuel container 11, is displaced between the first 27 and second 28 indexing positions by an adjusting member 26.2 of the device 25. The adjusting member 26.2 is provided, in its lower region, with a cavity 85 for the fuel container 11 and includes an actuation member 29.1 that can be actuated manually or mechanically, and an actuation member 29.2 that engages an end of the fuel container 11 remote from the metering head 20.

[0045] In FIG. 5, the metering head 20 is in its off or initial position 21 in which the metering head 20, together with the fuel container 11, is displaceable by the adjusting member 26.2 from the indexing position 27, 28 so to the next indexing position 28, 27, and all of the metering values 40, 50, 60, 70 are not actuated. The adjusting member 26.2 is fixed in the indexing positions 27, 28 with appropriate locking means.

[0046] In FIG. 6, as in FIG. 2, the metering head 20 is displaced by the adjusting cam 91 of the actuation device 90 in its operational position 22. The metering valves 50, 70, which have a larger metering chamber volume, are actuated and are connected with sub-chambers 15, 17 of the combustion chamber 12 by fuel passages 33, 34, so that respective fuel amounts are fed in the sub-chambers 15, 17.

[0047] The outlets 42, 62 of the metering values 40, 60 extend into the blind bore 37 and the units 46 are not actuated.

[0048] In FIG. 7, the fuel container 11, together with the metering head 20, are displaced in the second indexing position 28 by a pivotal movement of the adjusting member 26.2. In the indexing position 28, only metering valves 40, 60 with a smaller metering chamber volume are located opposite the fuel passages 33, 34. In all other aspects, reference is made to description with reference to FIGS. 1-4.

[0049] Though the present invention was shown and described with references to the preferred embodiments, such are merely illustrative of the present invention and are not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is therefore not intended that the present invention be limited to the disclosed embodiments or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A setting assembly for driving fastening elements in constructional components, comprising: a combustion energy-operated setting tool (10) having at least one combustion chamber (12); a fuel source (11); a metering head (20) for metering a predetermined amount of one of liquid fuel and gaseous fuel stored in the fuel source (11) into the at least one combustion chamber (12) of the setting tool (10), the metering head (20) having at least one inlet (23) communicating with the fuel source (11), at least two outlets (42, 52, 62, 72),.and at least two metering valves (40, 50, 60, 70) connected with the at least one inlet (23) and respective ones of the at least two outlets (42, 52, 62, 72) and having different volumes of respective metering chambers (41, 51, 61, 71) thereof; and a device (25) for selectively connecting the at least two outlets (42, 52, 62, 72) of the at least two metering valves (41, 51, 61, 71) with the at least one combustion chamber (12).

2. A setting tool assembly according to claim 1, wherein the selectively connecting device has an operational member (30.1, 30.2.) associated with at least one of metering head (2) and the combustion chamber (12) and having fuel passages (33; 34, 35) with stops (39) for supporting at least one of the at least two outlets (42, 52, 62, 72) of the metering head (20) and blind bores (36, 37) for receiving another one of the at least two outlets (42, 52, 62, 72) without actuating a respective metering valve (40, 50, 60, 70), and wherein the selectively connecting device (25) is displaceable between different indexing positions (27, 28) in which a respective other one of the fuel passages (33, 34, 35) and the blind bores (36, 37) is associated with each of the at least two metering valves (40, 50, 60, 70).

3. A setting tool assembly according to claim 2, wherein in each indexing position (27, 28) of the selectively connecting device (25), different fuel passages (33, 35, 36) and blind bores (36, 37) are associated with the at least two metering valves (40, 50, 60, 70).

4. A setting tool assembly according to claim 2, wherein the operational member (26.2) is formed as a slide (38) displaceably supported on a combustion chamber wall (18) for displacement relative to the outlets (42, 52, 62, 72) from one indexing position (27) of the selectively connecting device (25) to another indexing position (28) thereof.

5. A setting tool assembly according to claim 2, wherein the operational member (30.2) forms an integral part of a combustion chamber wall (18), and the metering head (20) with the metering valves (40, 50, 60, 70) is displaceably arranged opposite the member (30.2).

6. A setting tool assembly according to claim 2, further comprising an actuation device (90) for displacing the metering head (20) from an off-position (21) thereof in which the metering head (20) is spaced from the member (30.1, 30.2) and the at least two metering valves (40, 50, 60, 70) are closed, to an operational position (22) thereof in which at least one of the outlets (42, 52, 62, 72) of a respective one of the at least two metering valves (40, 50, 60, 70) extends into a respective fuel passage (33, 34, 35) and at least one of the at least two metering valves (40, 50, 60, 70) which is associated with the respective fuel passage (33, 34, 35) is actuated.

7. A setting tool assembly according to claim 3, wherein the at least two metering valves (40, 50, 60, 70) are arranged on the metering head (20) in a row, and the fuel passages (33, 34, 35) and the blind bores (36, 37) are likewise arranged in a row located opposite the row of the meeting valves (40, 50, 60, 70).

8. A setting tool assembly according to claim 2, further comprising electromechanical adjusting device (80) for displacing the metering head (20) and the member (30.1, 30.2) relative to each other from one indexing position (27) in another indexing position.

9. A setting tool assembly according to claim 2, wherein the member (30.2) is fixed on the setting tool (10), and the metering head (20) is displaceable between at least two indexing position (27, 28) relative to the fuel passages (33, 34), 35) and blind bores (36, 37).

10. A setting tool for driving fastening elements in constructional components, comprising: at least one combustion chamber (12) having a plurality of inlet openings provided in a combustion chamber wall (18) and connectable with a fuel source (11); and an operational member (30.1, 30.2) associated with the combustion chamber and having a plurality of fuel passages (33, 34, 35) with stops (39) for supporting outlets (42, 52, 62, 72) of metering valves (40, 50, 60, 70), which connect the inlet openings of the combustion chamber (12) with the fuel source (11), and a plurality of blind bores (36, 37) for receiving the outlets (42, 52, 62, 72) of the metering valves (40, 50, 60, 70). without actuating same.

11. A setting tool according to claim 10, wherein the operational member (30.1) is formed as a slide (38) displaceably supported on the combustion chamber wall (18) and displaceable relative to the outlets (42, 52, 62, 72). of the metering valves (40, 50, 60, 70) from one indexing position (27) into at least one further indexing position (28) thereof.

12. A setting tool according to claim 10, wherein the operational member (30.2) forms an integral part of the combustion chamber wall (18), and the metering valves (40, 50, 60, 70) are arranged in a metering head (20) displaceably arranged opposite the operational member (30.2).

13. A setting tool according to claim 12, further comprising an actuation device (90) for displacing the metering head (20), which is arranged on the setting tool, from an off-position (21) in which the metering head (20) is spaced from the member (30.1, 30.2) and all of the metering valves (40, 50, 60, 70) are closed, into an operational position (22) in which the outlets (42, 52, 62, 72) of the metering valves (40, 50, 60, 70) extend into respective fuel passages (33, 34, 35) and blind bores (36, 37), with the metering valves (40, 50,.60, 70) the outlets (42, 52, 62, 72) of which extend into the fuel passages being actuated.

14. A setting tool according to claim 10, wherein the fuel passages (33, 34, 35) and the blind bores (36, 37) are arranged on the operational member (30.1, 30.2) in a row, and the metering valves (40, 50, 60, 70) are arranged in a metering head (20) also in a row located opposite the row of fuel passages (33, 34, 35) and the blind bores (35, 37) on the operational member (30.1, 30.2).

15. A setting tool according to claim 14, further comprising an electromechanical adjusting device (80) for displacing one of the operational member (30.1, 30.2) and the metering head (20) from one indexing position (27) to another indexing position (28).

16. A setting tool according to claim 12, wherein the metering head (20) is displaceable between two indexing position (27, 28) relative to the fuel passages (33, 34, 35) and the blind bores (36, 37).

17. A metering head for metering a metered amount of one of liquid fuel and gaseous fuel into a combustion chamber of a setting tool (10), the metering head comprising: an inlet (23) connectable with a source of fuel (11); at least two outlets (42, 52, 62,.72); at least two metering valves (40, 50, 60, 70) connecting the inlet (23) with a respective one of the at least two outlets (42,;52, 62, 72) and having metering chambers (41, 51, 61, 71) with different volumes; and means (25) for selectively connecting the at least two outlets (42, 52, 62, 72) with the combustion chamber (12) of the setting tool (10).