Driving device

Abstract

The invention relates to a driving device comprising a hand-held housing in which there is accommodated a piston member for transmitting energy to a fastening element to be driven in, an interchangeable propellant and a combustion chamber arranged between the propellant and the piston member, said combustion chamber extending preferably about a central axis (A), and an actuator by means of which the energy that is transmissible from the propellant to the piston member is variable in a settable manner, wherein a discharge channel connected to the combustion chamber can be opened by means of a movable slide of the actuator, wherein a starting position of the piston member is variable in a settable manner by means of a second actuator.

Claims

1. A driving tool, comprising a handheld housing, having a piston member accommodated therein for transmitting energy to a fastening element to be driven in, the piston member having a starting position; a propellant charge; a combustion chamber arranged between the propellant charge and the piston member, extending about a central axis (A); a first control element, for variably adjusting energy transmitted from the propellant charge to the piston member, the first control element comprising a movable slide, wherein moving the slide exposes a blow-out channel connected to the combustion chamber; and, a second control element for variably adjusting the starting position of the piston member, wherein the first and second control elements are linked to each other.

2. The driving tool according to claim 1, wherein the slide is movable parallel to the axis (A).

3. The driving tool according to claim 2, wherein the blow-out channel has an exit cross-section that is variably adjustable according to the position of the slide.

4. The driving tool according to claim 2, wherein the second control element comprises an adjustable stop part, wherein the starting position of the piston member is defined by contact of the piston member with the stop part.

5. The driving tool according to claim 1, wherein the second control element comprises an adjustable stop part, wherein the starting position of the piston member is defined by contact of the piston member with the adjustable stop part.

6. The driving tool according to claim 1, wherein the combustion chamber is subdivided by a separating member having a plurality of perforations and a central region, into a first partial chamber adjoining the propellant charge and at least one second partial chamber adjoining the piston member, and wherein an ejection region for the propellant charge is provided in the first partial chamber, the ejection region extending between the propellant charge and the central region of the separating member.

7. The driving tool according to claim 6, wherein the ejection region is bounded at the central region of the separating member by a non-perforated surface of the separating member.

8. The driving tool according to claim 6, wherein the central region of the separating member has a depression.

9. The driving tool according to claim 1, wherein a maximum driving energy that can be adjusted by the first control element during ordinary operation corresponds, for an unchanged propellant charge, to at least twice a minimum driving energy adjustable by the first control element.

10. The driving tool according to claim 9, wherein the minimum driving energy is not more than 150 joules and the maximum driving energy is not less than 250 joules.

11. The driving tool according to claim 1, wherein the blow-out channel has an outlet cross-section that is variably adjustable according to the position of the slide.

12. The driving tool according to claim 1, wherein the second control element comprises an adjustable stop part, wherein the starting position of the piston member is defined by contact of the piston member with the stop part.

13. The driving tool according to claim 1, wherein the first and second control elements are linked to each other by a mechanical linkage.

14. The driving tool according to claim 13, wherein the first and second control elements are linked to each other by a slotted guide.

15. The driving tool according to claim 13, wherein the first and second control elements are linked to each other by a gear mechanism.

16. The driving tool according to claim 13, wherein the first and second control elements are linked to each other by a linkage rod.

17. The driving tool according to claim 1, wherein the first and second control elements are linked to each other by a only one operating member.

18. The driving tool according to claim 1, wherein the first and second control elements are adjusted via electrically operated actuators.

19. A system for driving a fastening element into a workpiece, comprising a driving tool comprising a handheld housing, having a piston member accommodated therein for transmitting energy to a fastening element to be driven in, the piston member having a starting position; a propellant charge; a combustion chamber arranged between the propellant charge and the piston member, extending about a central axis (A); a first control element, for variably adjusting energy transmitted from the propellant charge to the piston member, the first control element comprising a movable slide, wherein moving the slide exposes a blow-out channel connected to the combustion chamber; and, a second control element for variably adjusting the starting position of the piston member, wherein the first and second control elements are linked to each other; and a plurality of different fastening elements, wherein the system comprises only propellant charges with essentially identical propellant charge energy for covering a complete range of driving energies.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

(1) FIG. 1 shows a partial sectional view of a combustion chamber for a driving tool according to the invention at maximum driving energy.

(2) FIG. 2 shows the driving tool from FIG. 1 with a completely opened slide and with the starting position of the piston member shifted forward.

(3) FIG. 3 shows a three-dimensional sectional view of a combustion chamber of a driving tool having a separating member.

(4) FIG. 4 shows a three-dimensional detail view of the combustion chamber from FIG. 3.

(5) FIG. 5 shows a three-dimensional view of a separating member of the combustion chamber from FIG. 3.

(6) FIG. 6 shows a three-dimensional view of a combustion chamber having a second embodiment of a separating member.

(7) FIG. 7 shows a three-dimensional view of a combustion chamber having a third embodiment of a separating member.

(8) FIG. 8 shows a three-dimensional view of a combustion chamber having a fourth embodiment of a separating member.

DETAILED DESCRIPTION OF THE INVENTION

(9) A driving tool according to the invention comprises a handheld housing in which a piston member in the form of a piston 2 is accommodated. A surface 2a of the piston 2 delimits a combustion chamber 3, in which the combustion gases of a pyrotechnic charge expand in order to accelerate the piston 2. The pyrotechnic charge is solid, preferably in the form of powder. In examples that are not shown, the pyrotechnic charge is liquid or gaseous.

(10) The piston 2 to which kinetic energy has been applied in this manner strikes with its piston shaft against a fastening element, which is thereby driven into a workpiece.

(11) The charge is held in the present case in a cartridge made of sheet metal. The cartridge has a percussion igniter and is inserted before ignition into a cartridge support 4 via an appropriate loading mechanism.

(12) The cartridge and the cartridge support are preferably formed so as to be rotationally symmetrical about a central axis A. The central axis A in the present examples is simultaneously a center axis of the combustion chamber 3 and the piston 2.

(13) The combustion chamber 3 is arranged between a cylindrical opening 4a of the cartridge support 4 and the surface 2a of the piston 2. In a possible detailed design, an annular depression 2b is formed in the piston 2, which contributes to a better turbulence formation in the combustion gases and constitutes a part of the combustion chamber 3.

(14) The combustion chamber 3 in the present case has a side wall 101, which is formed as a rotational surface of a parallel line about the central axis A, i.e. as an internal cylinder. The combustion chamber 3 additionally has a base surface 102, which extends substantially perpendicular to the axis A.

(15) Two control elements 104, 108 are provided for adjustably varying the kinetic energy absorbed by the piston member 2 for a given propellant charge, and thus for adjustably varying a driving energy for the fastening means.

(16) The first control element 104 comprises a recess 103 that is parallel to the combustion chamber and guides a slide 105. The control element 104 also comprises a mechanism (not shown) for displacing a position of the slide 105. The slide is shown in FIGS. 1 and 2 with crosshatching for better understanding.

(17) The slide 105 is accommodated in the recess 103 in a housing enclosing the combustion chamber. In this recess, the slide 103 is adjustable in position parallel to the central axis A. For this purpose, an external thread (not shown) can be formed on the rear end of the slider 105, for example. The external thread can then run in an internal thread of a rotatably mounted gear supported in the axial direction. If the gear is driven, the slide 105 can be displaced in the axial direction by the rotation of the thread. The mechanism displacing the slide 105 can be designed as desired.

(18) Depending on the requirements, the slide can be displaced manually, by an adjustment wheel, not shown, for example. The displacement can also involve an electrical actuator, however. An at least partially automatic adjustment of the driving energy can be accomplished by an electronic tool controller. The necessary specifications, such as the type and dimensioning of the workpiece, can be provided by an operator. Sensor information, regarding the type of fastening means that has been loaded for example, can be used alternatively or additionally.

(19) The recess 103 is connected via an opening 106 to the combustion chamber 3. A channel 107 parallel to the combustion chamber leads to the front in the driving direction.

(20) The slide 105 fills up the recess 103 and additionally has an axially extending bore 109 open at the front and having a lateral opening 110 that is oriented in the direction of the perforation 106.

(21) Depending on the position of the slide 105, the lateral opening 110 does not cover the perforation 106 at all, covers it partially or covers it completely. In this way, the volume of the combustion chamber 3 can be connected via an adjustably variable cross section to the bore 109 and the channel 107.

(22) If the slider is in an appropriate position, the opening 110, the bore 109 and the channel 107 together form a blow-out channel 111. After an ignition of the pyrotechnic propellant charge, expanding gases can escape partly into the blow-out channel, depending on the opening status thereof. This reduces the kinetic energy or driving energy that is ultimately absorbed by the piston member 2.

(23) The blow-out channel 111 in the present case opens into a gas channel, not shown, at a guide for the piston member 2 located in front of the combustion chamber 3. The channel ends in a known manner in a storage chamber (not shown). At the end of the driving process, the piston member 2 is moved back into the initial position in a known manner by means of the combustion gases collected in the storage chamber. In alternative embodiments, the blow-out channel 111 can also open directly into the atmosphere.

(24) A second control element for varying the driving energy is designed as an adjustable stop part 108. A starting position of the piston member 2 is variably defined in this case by the stop for the piston member 2 on the stop part 108.

(25) In the present case, the stop part is formed as a rod 108 penetrating into the combustion chamber 3. The rod can be moved in the axial direction by a mechanism, not shown. In particular, analogously to a possible displacement of the slide 105, a thread and an operating part such as an adjusting wheel can be provided for displacing the rod 108.

(26) In the maximal energy position according to FIG. 1, a base surface 2a of the piston member 2 contacts the base surface 102 of the combustion chamber 3 in the initial state of the piston member 2. This implies a maximum acceleration path of the piston and a minimal starting volume of the combustion chamber at the charge ignition time. Since the blow-out channel 111 is also completely closed, a maximum driving energy is achieved.

(27) If the rod 108 is displaced from the position shown in FIG. 1 into the combustion chamber, the starting position or initial position of the piston member 2 is shifted forward, see FIG. 2. This leads to a larger combustion chamber volume and a smaller acceleration path of the piston member 2.

(28) If necessary, a pressure buildup in the combustion chamber 3 is further reduced by partial or complete opening of the blow-out channel 111; see the opened position of the slide 105 in FIG. 2. The driving energy achieved by the piston member 2 is reduced overall in this way. In the positions of the slide 105 and the second control element 108 according to FIG. 2, there is a maximally opened blow-out channel 111 and a maximum shift forward of the piston member 2. This achieves the smallest possible value for the driving energy with a given propellant charge.

(29) The two control elements 104, 108 can be adjusted entirely independently of one another, so that the reduction of driving energy achieved results as an overlapping of the two respective effects.

(30) It should be noted with regard to the slide 105 of the first control element that the opened position in the present case is achieved by shifting the slide to the rear. A front part of the perforation 106 is first exposed. In a partially open position, this has a different effect on the driving energy than if initially an equally large rear part of the opening 106 were exposed. Depending on the requirements, the slide can also be adjusted in this way, so that overall even more precise optimizations of the combustion process and the driving energy are available.

(31) With regard to the rod or the stop part of the second control element 108, it should be noted that it can be retracted out of the combustion chamber if needed, before an ignition of the propellant charge, after the starting position of the piston member 2 has been previously set stopping the piston bottom.

(32) The discussion below relates to optimized designs of the combustion chamber in the driving tool by means of the separating member. Although no control element for varying the driving energy is shown in the drawings of FIGS. 3-8, the designs of the combustion chamber with a separating member can be combined with the above described designs of a control element 104, depending on the requirements.

(33) The combustion chamber 3 is subdivided transversely to the central axis A by a separating member 5. A first partial chamber 3a of the combustion chamber is situated on the side of the cartridge support 4, and a second partial chamber 3b of the combustion chamber 3 is situated on the side of the piston 2.

(34) In the drawings of FIGS. 3-8, the piston is maximally retracted, so that the second partial chamber 3b includes only the depression 2b and possibly a narrow gap between the piston 2 and separating member 5 at the time of ignition.

(35) The separating member 5 in the present case is formed as a component that can be screwed into the combustion chamber 3 by means of an external thread 7. The separating member can also be integrally formed with the remainder of the combustion chamber or connected in some other way as a separate component to the combustion chamber.

(36) The separating member 5 has a plurality of perforations 6, which are constructed in the present case as bores that run parallel to the axis A. The perforations 6 are arranged about a central region 8 of the separating member 5 that has a contiguous and non-perforated surface. The smallest diameter of the central, non-perforated region 8 in the plane perpendicular to the axis A is approximately 35% smaller than the diameter of the cartridge when opened after ignition. In this case, this region corresponds approximately to the diameter of an opening of the cartridge support on the combustion chamber side or of a surface of the pyrotechnic charge directed into the combustion chamber.

(37) It is currently assumed that the combustion gases and powder grains, charge particles or the like that are ejected along with them initially travel parallel to the central axis into the combustion chamber. At least directly after ignition and over a certain length, the expanding charge therefore moves predominantly along the axis in a prismatic ejection region, the outline of which is defined by the surface of the charge. In the present embodiments of the invention, all the perforations 6 of the separating member are outside an intersection surface of the ejection region with the surface of the separating member. Corresponding to the circular cartridge opening, the ejection region is formed as a cylinder.

(38) A depression 9 is also formed in the central region 8 of the separating member 5. The depression 9 runs rotationally symmetrically about the central axis A. It has a bowl shape and a flat bottom 9a. The diameter of the depression 9 tapers from a largest diameter d at the upper edge thereof to a smallest diameter at the level of the bottom 9a. The walls of the depression 9 have both inclined and straight portions. The maximum depth of the depression 9 in this case is approximately 60% of the largest diameter d.

(39) In the plane of the upper edge of the depression 9, the closed surface of the central region 8 extends up to a gradation 10. This gradation 10 rises in the axial direction from the surface of the central region 8 to a roof of the combustion chamber 3. The separating member 5 is pressed with the gradation 10 against the roof in the present case. This is achieved by screwing the separating member 5 into the combustion chamber 3 appropriately.

(40) The gradation 10 forms respective inwardly-directed ridges 11 between adjacent perforations 6. Accordingly, radially directed channels 12 remain between the ridges 11, through which the combustion gases and particles of the charge initially flow radially outward from the central region 8 and then are deflected into the perforations 6.

(41) The invention operates in relation to the separating member as follows:

(42) After ignition of the cartridge, as yet non-combusted particles are accelerated ahead of a front of combustion gases through the interior cartridge opening into the first partial chamber 3a. After a short travel, this partially non-combusted part of the charge strikes the bowl-shaped depression 9 of the contiguous central region 8 of the separating member 5. The powder grains and combustion gases are scattered and become turbulent there, and the powder grains continue to ignite and burn. This reacting and expanding mixture passes in a predominantly radial direction between the ridges 11 and is deflected into the perforations 6.

(43) When passing through the perforations 6, the particles of the charge have already predominantly combusted, so that large non-combusted charge residues do not remain in the perforations or in the downstream second partial chamber 3b. This prevents unfavorable deposits and/or clogging of the perforations 6. At the same time, a controlled and uniform expansion of the combustion gases in the second partial chamber is favored, so that the piston 2 is optimally accelerated.

(44) In the second example of a separating member, which is shown in FIG. 6, the depression 9 is shaped differently. As in the first example, the depression is constructed as a bowl-like recess, but the walls of the depression are more sharply and continuously inclined.

(45) In the embodiment of a separating member shown in FIG. 7, the shaping of the depression 9 is largely as in the example of FIG. 6. In addition, a projecting conical protrusion 13 is formed above the bottom of the depression. The conical protrusion 13 causes a significant scattering and turbulence of the combustion gases.

(46) In the embodiment of a separating member shown in FIG. 8, the depression 9 does not have a flat bottom but rather a predominantly parabolic cross section overall. Such a shape is particularly well-suited to avoid deposits.

(47) It is understood that the invention is not limited to the shapes of the depression 9 that are shown for the sake of example.

(48) As a whole, a system for driving a fastening element into a workpiece is provided by a driving tool as described above, in conjunction with a propellant charge and a selection of fastening means. The system comprises a plurality of different fastening means, and only one type of propellant charge is necessary to cover a complete range of driving energies.

(49) The driving energy transmitted to the piston member extends from a minimum driving energy of 90 joules to a maximum driving energy of 325 joules, using the same propellant charge.