EP0620085A1 - Release safety device for a fastener driving tool - Google Patents

Abstract

Release safety device for a driving tool, with a working cylinder, a driving ram fixed to the working piston, a control valve arrangement for piston movement to the bottom dead centre and to the top dead centre, a piston return chamber connected to the working cylinder via a first opening close to the bottom dead centre and a second opening at a distance from the bottom dead centre, a mouth tool with a driving channel, with an opening to a magazine, a feeling device with a feeling head displaceable in the setting-on direction and feeling slide coupled thereto with a bearing surface transverse to its displacement direction, a release for displacing the valve rod with a pivotable valve lever and an operating lever fixed thereto, the free end of the operating lever being supported by the bearing surface before actuation of the feeling device and before actuation of the release, remaining supported by the bearing surface upon actuation of the feeling device and subsequent actuation of the release, with the result that the operating lever actuates the valve rod, and sliding off the bearing surface upon actuation of the release without actuation of the feeling device, without the operating lever displacing the valve rod, the feeling device being assigned a locking device which locks the feeling device upon actuation of the valve rod and unlocks the feeling device upon freeing of the valve rod. <IMAGE>

Description

The invention relates to a trigger protection on a device operated with compressed air for driving in fasteners according to the preamble of claim 1.

The invention relates to driving tools that suddenly drive a fastener into a workpiece. The impact pulse is caused by a piston, which performs a working stroke when it is suddenly exposed to compressed air. High impact energies are effective, which hurl a fastener over long distances if the device is not with a muzzle tool on the Workpiece is placed. A hazard to people from free-floating fasteners is avoided by the safety devices that are required for driving tools today. These have a probe at the outlet opening of the mouth tool, which is actuated when the driving tool is placed on a workpiece. Only when the probe is actuated is it possible to initiate a driving process by actuating a finger trigger.

From DE-AS 26 01 836 a trigger protection on a tacker is known in which the control valve arrangement for the piston movement has a valve rod, the actuation of which triggers a working stroke and the relief of which causes a return stroke of the working piston. A trigger for finger actuation is assigned to one end of the valve rod and has a valve lever pivotably mounted on a device housing. At the free end of the valve lever, a gear lever is pivotally mounted, which has a free gear lever end below the pivot bearing of the valve lever. When the device is aligned vertically, the free end of the shift lever rests on a support surface of a slide switch that is connected to the probe. If the probe is actuated by placing it on a workpiece, the probe slide with the swivel arm end resting on it is for swivel mounting of the valve lever shifted. When the trigger is subsequently actuated by pivoting the valve lever, the switching lever hits the valve rod and shifts it by its actuation stroke. This triggers the driving process. However, if the mouth tool with the probe is not seated on a workpiece, the probe slide is moved to a lower position due to the action of gravity. The swivel lever supported on it cannot be brought into contact with the valve rod by swiveling the valve lever. This means that no drive-in process can be triggered without actuating the probe.

In practice, the known driving tool has the disadvantage that the driving process can also be triggered by placing the probe on a workpiece when the pivoting lever is actuated (so-called "touching"). During use, therefore, the trigger is often actuated permanently and the driving-in process is only controlled by placing it on the workpiece. This can lead to dangerous false triggers if the probe is actuated by unintentional contact or acceleration and thereby triggers a shooting process. According to more recent regulations, this simple trigger protection is no longer permissible in all applications.

In the case of a further developed protection against tripping, the switch lever only has a short end area on the contact surface of the slide switch. The shift lever is supported on the valve stem by a compression spring and the push button is held in a lower position by a pneumatic piston with spring support in the unactuated state. When the probe is actuated, the slide switch with the end of the shift lever is raised against the action of the pneumatic piston. Subsequent actuation of the valve lever leads to actuation of the valve rod by the switching lever and triggers the driving-in process. However, if the valve lever is swiveled while the probe is not actuated, the free end of the shift lever slides off the contact surface next to the push button. There, the end remains on a surface fixed to the housing without being raised when the valve lever is pivoted. As a result, the shift lever does not come into contact with the valve rod and cannot trigger a driving process. Tripping without prior actuation of the pushbutton device is therefore not possible. The user cannot control the firing process by simply pressing the muzzle tool when the trigger is permanently activated. However, malfunctions often occur with this driving tool. After a driving-in process, often no further triggering can be effected by simply actuating the trigger.

The same applies if the device is pulled off the workpiece while the trigger is actuated. Then the device must be lifted off the workpiece, the trigger released and pressed again to deliver another fastener.

Proceeding from this, the object of the invention is to provide an improved trigger safeguard on a driving device for fastening means, in which each driving operation requires a trigger actuation, wherein no trigger preparations are required apart from the trigger actuation.

The solution to the problem is specified in claim 1. Advantageous refinements are contained in the subclaims.

The invention is based on the following findings about the recoil effects during the driving-in process: Due to the high driving-in pulse, the driving-in device can lift off the workpiece for a short time, the resetting device moving the pushbutton device back into its starting position. The trigger is actuated because the kickback occurs in fractions of a second after the driving process has been triggered. During the return movement of the push button, however, the spring-loaded switching lever can be moved from the Slide the support surface next to the slide. When the device is replaced, the slide moves laterally past the free end of the shift lever so that it remains on the surface fixed to the housing. If the driving tool is now moved to a new driving point without lowering the muzzle tool, the driving process cannot be effected simply by actuating the trigger. The free shift lever end namely maintains its lowest position, which does not allow valve rod actuation when pivoting the valve lever. Another driving-in process requires the lifting of the device from the workpiece and the associated shifting of the push button in the lower position. Furthermore, the user must let go of the valve lever so that the free end of the shift lever returns to the contact surface of the push button. Then the muzzle tool has to be put on, whereby the free end of the shift lever returns to its raised position. Finally, the shot can be effected by actuating the trigger.

It is therefore important to prevent the probe device from moving backwards when the mouth tool is lifted off the workpiece as a result of the recoil. In general, it must be prevented that the feeler device returns to its initial position when the driving tool is at actuated valve rod is lifted from the workpiece, which can also be done arbitrarily by the user. Therefore, according to the invention, the locking device is assigned a locking device which locks the locking device when the valve rod is actuated in the actuating position and unlocks the locking device when the valve rod is released. If the trigger actuation has resulted in a driving-in process, the pushbutton device is held in its actuating position until the trigger is released again in preparation for a new driving-in process. This ensures that the free shift lever end remains on the contact surface of the push button. At the same time, it is ensured that the triggering of a further shot is only possible when the pushbutton is actuated.

The locking device can have a locking piston coupled to the push-button slide in a locking cylinder, a control line loading the locking piston with a working pressure for locking in the actuating direction of the push-button slide and ventilated when unlocked. For this purpose, the control line can be connected to the piston return chamber, which takes on working pressure during the working stroke of the piston and is aerated after the piston return stroke. The flow resistance of the Control line is set so that the locking piston is acted upon in time with a sufficient working pressure before the recoil enables the pushbutton device to move back into its starting position.

For timely activation of the locking piston, the control line can be connected to the working cylinder via a third opening at a distance from bottom dead center. Another variant provides for connecting the control line to an auxiliary valve on the valve rod, as a result of which the lock is more closely coupled to the valve rod actuation.

For resetting the pushbutton device in the starting position, a compression spring is preferably provided which acts against the actuating direction of the pushbutton on the locking piston.

The slide switch can have a C-shaped receptacle in cross section, the lower limit of which forms the contact surface for the free end of the shift lever and the upper limit of which is connected to the locking piston. The receptacle designed in this way can also accommodate the pivot bearing of the valve lever. In addition to the slide switch, an immovable support surface for this is preferred Free shift lever end arranged, which is aligned with the support surface before actuation of the feeler. If the free shift lever end slips off the support surface, it is held by the support surface at a level at which it can easily return to the support surface after releasing the trigger and unactuated pushbutton.

Finally, a practical embodiment provides that a compression spring is arranged between the shift lever and the valve rod, which always holds the shift lever in a defined position. The compression springs of the locking piston and shift lever together have the effect that the driving tool can be used in any orientation to the vertical.

Fig. 1

ein Eintreibgerät für Klammern, Nägel oder dergleichen mit Verriegelungsluft aus der Kolbenrückholkammer im Ruhezustand und im Längsschnitt durch den Vorderbereich;

Fig. 2

dasselbe Gerät während des Arbeitshubes des Arbeitskolbens in derselben Schnittdarstellung;

Fig. 3

ein Eintreibgerät mit Verriegelungsluft aus einer dritten Öffnung des Arbeitszylinders im Ruhezustand und im Längsschnitt durch den Vorderbereich;

Fig. 4

dasselbe Gerät während des Arbeitshubes des Arbeitskolbens in demselben Schnitt;

Fig. 5

Eintreibgerät mit Verriegelungsluft aus einem Hilfsventil an der Ventilstange im Ruhezustand und in einem Längsschnitt durch den Vorderbereich;

Fig. 6

Tasteinrichtung und Auslöser desselben Gerätes in vergrößertem Teilschnitt;

Fig. 7

dasselbe Gerät während des Arbeitshubes des Arbeitskolbens in einem Längsschnitt durch den Vorderbereich;

Fig. 8

Tasteinrichtung und Auslöser gemäß Fig. 7 in vergrößertem Teilschnitt.

Further details and advantages of the invention will become apparent from the following description of the accompanying drawings, which show preferred configurations. The drawings show:

Fig. 1

a driving tool for staples, nails or the like with locking air from the piston return chamber in the idle state and in longitudinal section through the front area;

Fig. 2

the same device during the working stroke of the working piston in the same sectional view;

Fig. 3

a driving tool with locking air from a third opening of the working cylinder in the idle state and in longitudinal section through the front area;

Fig. 4

the same device in the same cut during the working stroke of the working piston;

Fig. 5

Driver with locking air from an auxiliary valve on the valve stem in the idle state and in a longitudinal section through the front area;

Fig. 6

Push button and trigger of the same device in an enlarged partial section;

Fig. 7

the same device during the working stroke of the working piston in a longitudinal section through the front area;

Fig. 8

7 in an enlarged partial section.

In the following description of various embodiments matching device parts are provided with identical reference numbers. In this respect, the description applies to all embodiments.

All driving tools have a housing 1 with a housing handle 2 and a housing head 3 at the front end. A muzzle tool 4 is attached to the bottom of each working head. The mouth tool 4 is supplied with fasteners from a magazine 5. In addition, a probe device 6 is provided, which projects above the lower end of the mouth tool 4 with a probe 7. Finally, there is a pivotable trigger 8 for finger actuation.

In the housing handle 2 there is a compressed air supply space 9 which extends into an upper part of the housing head 3 and to which a compressed air source can be connected. In the housing head 3 there is a working cylinder 10 in which a working piston 11 is arranged. The working piston 11 is connected at its lower end to a driving plunger 12 which is guided in a driving channel 13 of the mouth tool 4. The magazine 5 leads - through an opening (not shown) - to the drive channel 13 in each case by a fastening means. From its top dead center, the piston 11 is up to an elastic brake ring 14 in the bottom Movable dead center, driving a fastener into a base. For this purpose, the drive-in channel 13 has an outlet opening 15 at the lower end of the mouth tool 4.

A control valve arrangement 16 is provided for the abrupt movement of the piston 11 from top to bottom dead center and for its return movement from bottom to top dead center. This essentially has a valve rod 17 and a valve arrangement 18, which is arranged above the working cylinder 10. The control valve arrangement 16 has the function of connecting the compressed air supply chamber 9 to the working cylinder 10 above the working piston 11 by actuating the valve rod by axially displacing it upward, in order to drive it from the top dead center to the bottom dead center. In addition, the control valve arrangement 16 has the function of connecting the working cylinder 10 above the working piston 11 with atmosphere when the valve rod 17 moves downward until its collar 19 abuts against a stop, so that air located below the working piston from a piston return chamber 20 moves the working piston from drives back to top dead center. DE-AS 26 01 836 describes a control valve arrangement which has these functions and is suitable for realizing the invention. The Control valve arrangement according to the drawing also belongs to the prior art and is therefore explained below only with regard to its most important features.

The valve rod 17 has a return spring 21 which moves it back into its starting position after relief. At the bottom, the valve rod 17 is guided through a sealing bush 22 of the housing. At the top, it forms an auxiliary valve 24 with a bushing 23. When the valve rod is not actuated (FIGS. 1, 3, 5), the auxiliary valve connects the compressed air supply chamber 9 to a control chamber 25 above the working cylinder 10. When the valve rod 17 is actuated (FIGS. 2, 4, 7 ) connects the auxiliary valve 24 to the control chamber 25 via an exhaust air chamber 26 and a filter 27 with atmosphere.

The control wheel 25 is delimited at the bottom by a control piston 28 and at the top by a housing wall 29. The housing wall 29 has a sealing passage for a tubular extension 30 of the control piston 19. In addition, a helical spring 31 is supported between the upper housing wall 29 and the control piston 28. Finally, a sleeve-shaped valve seat element 33 is sealingly guided in a receptacle of a housing cover 32.

Before actuation of the valve rod 17 causes the Auxiliary valve 24 working pressure exerted on the top of the control piston 28 together with any pre-tensioning of the helical spring 31 so that the valve piston is pressed with its lower edge against a working pressure acting on its outer edge circumference from below with its lower edge against the upper edge of the working cylinder 10 (Fig. 1, 3 and 5). When the valve rod 17 is actuated, on the other hand, the upper side of the control piston 28 is ventilated, so that it is moved by the working pressure acting on the underside into an upper position in which it lies sealingly against the upper housing wall 29 and with its attachment 30 sealingly against the valve seat element 33. Then the space of the working cylinder above the piston 11 is no longer connected to the atmosphere via the exhaust air space 26, so that compressed air from the compressed air supply space 9 drives the piston to the brake ring 14 (FIGS. 2, 4, 7).

When the working piston 11 moves to the bottom dead center, the piston return chamber 20 is filled with compressed air via a second opening 34 of the working cylinder 10 at a distance from the bottom dead center. The piston return space 20 communicates with the lower side of the working piston 11 via a first opening 35 near the bottom dead center.

The air in the piston return chamber 20 can only push the working piston 11 back from its lower to the upper dead center position when the working cylinder 10 is again separated from the compressed air supply chamber 9 and ventilated. For this purpose, the valve rod 17 is to be relieved, so that it returns to its starting position with the collar 19 in the stop on the bushing 22. Then the compressed air reservoir 9 is placed on the top of the control piston 28 via the auxiliary valve 24. Together with the force of the compressed helical spring 31, the pressure on the upper side, in opposition to the working pressure acting on the underside, brings the working piston 28 back into the starting position (FIGS. 1, 3, 5). The valve seat element 33 follows the movement of the tubular extension 30 until it is retained by an upper edge of the upper housing wall 29. This prevents compressed air losses due to an outflow through the attachment 30 and exhaust air space 26. However, if the control piston 28 lies sealingly on the upper edge of the working cylinder 10, residual air can escape through the attachment 30 and the exhaust air space 26, the valve seat element 33 returning to its upper starting position.

Furthermore, it is common to all the drawn variants that the probe device 6, starting from the probe head 7, has a bracket 36 which is guided to a slide switch 37. The Touch slide 37 has a longitudinal slot 38 which is guided on a bolt 39 fixed to the housing. At the top, the slide valve 37 has a C-shaped receptacle 40, the lower limit of which forms a support surface 41. An upper limit 42 of the receptacle 40 is fixedly connected to a shaft 43 of a locking piston 44. The piston shaft 43 is guided through a housing seal 45. The locking piston 44 is sealingly guided in a locking cylinder 46. The piston 44 is supported in the locking cylinder 46 via a helical spring 47. The locking cylinder 46 has a vent hole 48. On the other side of the piston, a control line 49 opens into the locking cylinder 46.

The trigger 8 has a valve lever 50 which has a pivot bearing 51 in the receptacle 40 of the push-button slide 37. A switching lever 52 is mounted in the valve lever 50 near the free end thereof. The shift lever 52 extends in the opposite direction to the valve lever 50 and has a short, cranked free shift lever end 53. In all drawings, the free shift lever end 53 rests on the contact surface 41 of the push-button slide 37.

In addition to the slide switch 37, a support surface 54 is arranged in the form of a sheet that is angled horizontally at the top.

The support surface 54 is aligned with the contact surface 41 when the pushbutton device 7 is not actuated.

A coil spring 55 is supported between the shift lever 52 and the lower end of the valve rod 17.

In the variant of FIGS. 1 and 2, the control line 49 is connected directly to the piston return chamber 20. In the variant according to FIGS. 3 and 4, the control line 49 is guided to a third bore 56 of the working cylinder 10, which is spaced further from the brake ring 14 than the bore 34.

In the version according to FIGS. 5 to 8, the control line 49 is led to a further auxiliary valve 57, which is arranged at the lower end of the valve rod 17.

6, the auxiliary valve 57 has a socket 58, an annular channel 59 being formed between the socket and the housing 1, into which the control line 49 opens. The ring channel 59 is connected via bores 60 to an annular gap 61 which is formed between a tapered section of the valve rod 17 and the bushing 58. O-rings 62, 63 are seated on the valve rod section, one of which each has an associated sealing surface of the bushing 58 in Sealing arrives. On the outside, the bushing 58 is sealed off from the housing 1 by further O-rings 64, 65 on both sides of the ring channel 59.

When the valve rod 17 is not actuated, the control line 49 is thus connected to the atmosphere via the auxiliary valve 57. When actuated, the valve rod 17 is moved upward, whereby the control line 49 is connected to the compressed air storage space 9.

In all the illustrated device variants, no driving-in process can be triggered by actuating the valve lever 50 if the probe device 6 with its probe head 7 is not placed on a workpiece. 1, 3 and 5, so that the switching lever 52 when pivoting the valve lever 50 upwards with its free switching lever end 53 from the support surface 41 on the Support surface 54 slips. The pivot path of the valve lever 50 is then not sufficient to press the switching lever 52 against the valve rod 17 from below and to actuate it.

However, if the mouth tool 4 is first placed on a workpiece, the probe 7 at the level of the outlet opening 5 is shifted, the free shift lever end 53 is also moved a bit upwards. The prerequisite for this is that the switching lever 52 rests on the support surface 41 when the pushbutton 6 is actuated. When the trigger 8 is subsequently actuated, the switching lever 52 is forced against the lower end of the valve rod 17, as a result of which the working stroke of the working piston 11 described above is triggered. The locking piston 44 is loaded by the respective control lines 49 so that the key slide is held in its upper position. 2 this is achieved via the pressure in the piston return chamber 20 which builds up during the piston stroke. 4, the locking is effected somewhat earlier by the pressure in the working cylinder 10. 7 and 8, the second auxiliary valve 57 brings about the build-up of the pressure on the locking piston 44 as a direct consequence of the actuation of the valve rod 17.

As long as the trigger 8 remains actuated after the locking device 6 has been locked, the locking remains. Only after release of the trigger 8 does the valve rod 17 return to its starting position due to the return spring 21 and the piston 11 strives towards its top dead center in the manner described above. Then the pressure drops from the return chamber 20 or in the working cylinder 10 below the piston 11 and the second auxiliary valve 57 is reconnected to the atmosphere. As a result, the pressure below the locking piston 44 drops to the atmospheric level and the locking of the sensing device 6 is released. Then the coil spring 47 forces it back into its starting position.

In the event of a recoil due to the recoil during the driving-in process, the locking of the sensing device 6 prevents the switching lever 52 from sliding off the support surface 41 and not triggering the valve rod 17 when the trigger 8 is subsequently actuated. It is also achieved according to the invention that a lifting of the device from a workpiece when the trigger 8 is actuated does not preclude a further individual triggering after subsequent replacement.

Claims (10)

Protection against tripping on a device operated with compressed air for driving in fasteners, with a working cylinder (10) in which a working piston (11) can move between an upper and a lower dead center, a driving plunger (12) fastened to the working piston, a control valve arrangement (18) which, when a valve rod (17) is actuated, connects a working cubic space above the working piston for piston movement to bottom dead center with compressed air and, when the valve rod for piston movement to top dead center is relieved, to an atmosphere, a piston return chamber (20) surrounding the working cylinder, which has a first opening ( 35) near the bottom dead center and a second opening (34) at a distance from bottom dead center is connected to the working cylinder, an orifice tool (4) with a driving channel (13) leading the driving plunger, with an opening opening into the movement area of the driving plunger to one Magazine (5) for fastening m means, a probe device (6) with a probe head (7) which extends below the discharge opening (15) of the muzzle tool and can be displaced in the mounting direction, and a probe slide (37) coupled thereto with a contact surface (41) transverse to its direction of displacement, a trigger (8) for displacing the valve rod (17) with a pivotable valve lever (50) and a switching lever (52) attached to the valve rod, which is pivotably mounted near the free valve lever end and a free switching lever end (53) near the pivoted valve lever end The free shift lever end before actuating the feeler device (6) by moving the probe head (7) when placed on a workpiece and before actuating the trigger (8) by pivoting the valve lever (50) towards the valve rod (17) from the support surface ( 41) is supported, when the pushbutton (6) and subsequent actuation of the trigger (8) is supported by the support surface, so that the switching lever (52) actuates the valve rod (17), and when the trigger (8) is actuated without actuation the feeler device (6) slips off the support surface (41) without the switching lever (52) displacing the valve rod (17), thereby indicates that the push button (6) is assigned a locking device (44, 46) which locks the push button in the actuating position when the valve rod (17) is actuated and unlocks the push button when the valve rod is released. Tripping safety device according to claim 1, characterized in that the push button (37) is coupled to a displaceable locking piston (44) in a locking cylinder (46) and a control line (49) loads the locking piston with working pressure when locked in the actuating direction of the push button (37) and ventilated when unlocked. Tripping safety device according to claim 2, characterized in that the control line (49) is connected to the piston return chamber (20). Tripping device according to claim 2, characterized in that the control line (49) is connected to the working cylinder (10) via a third opening (56) at a greater distance than the second opening (34) from the bottom dead center. Tripping safety device according to claim 2, characterized in that the control line (49) is connected to an auxiliary valve (57) on the valve rod (17). Tripping device according to one of Claims 1 to 5, characterized in that a compression spring (47) on the locking piston counter to the actuation direction of the push-button slide (37) (44) acts. Tripping device according to one of claims 1 to 6, characterized in that the push button (37) has at the top a C-shaped receptacle (40), the lower limit of which forms the contact surface (41) for the free lever end (53) and the upper Limit (42) is connected to the locking piston (44). Trigger lock according to claim 7, characterized in that the receptacle (40) receives the pivot bearing (51) of the valve lever (50). Tripping device according to one of claims 1 to 8, characterized in that an immovable support surface (54) for the free switching lever end (53) is arranged next to the push button (37), which is aligned with the contact surface (41) before actuation of the push button device (6) . Tripping device according to one of claims 1 to 9, characterized in that a compression spring (55) is arranged between the switching lever (52) and the valve rod (17).

Images