EP0744250B1 - Fastener driving tool - Google Patents

Description

The invention relates to a fastener driving tool according to the preamble of claim 1.

Such a driving tool is e.g. from DE-A-2 601 836 known.

Such driving tools have a muzzle tool an ejection channel through which fasteners are expelled can be. The ejection channel is one side-fed magazine. Across the food opening is a plunger that can be moved with a Ejection movement of a fastener from the muzzle tool pushes out. The plunger is on a working piston held, which is arranged in a working cylinder. The working displacement above the working piston is at filled with compressed air during a driving process. For the return movement the working piston to its initial position ventilated. There can be a working displacement below the working cylinder with return air to drive the piston back be filled.

For controlling the air in the upper working stroke of the Piston assemblies are used. For smaller ones Series are known as "parallel valves" that arranged parallel to the working piston and directly one Trigger switches are assigned. With "head valve units" there is a valve arrangement directly above the working cylinder. Larger in the open position Flow cross sections between the working cubic space and compressed air reservoir released so that the driving process with significantly improved efficiency expires.

"Top valves" have a valve piston above the cylinder, the one in a lower position with the compressed air source connected inlet duct to the upper working stroke of the working cylinder shut off. The valve piston sits for this with the bottom sealing on the upper edge of the cylinder. In an upper position, the Valve piston from an outlet channel, which has a through hole of the valve piston connected to the working displacement is. For this purpose, the valve piston can have a hollow cylindrical top and have the piston bearing bore, the is sealingly guided in a socket and in the upper Position sealingly against a valve seat element. The Can also act as a stop for the top of the Serve valve piston around the hollow cylindrical piston neck.

For the movement between the lower and the upper position the valve piston has a lower effective area that is constantly acted upon by the compressed air source. Further he has an upper effective area, which is by means of a control valve either with atmospheric pressure or from Compressed air source can be acted upon. The control valve can arranged next to the valve piston and by means of a the housing-guided valve rod can be actuated by a trigger be. The control valve can also directly sit next to the trigger and over a longer control channel be connected to the main valve.

The valve piston can be used for sealing in its lower position made of plastic directly on the top of the cylinder sit on. Minor damage to the sealing surface can cause leaks. In addition, such valve pistons work in, so that at an exchange for repair purposes also leaks can occur. As a result, you provide that The valve piston usually has an elastic seal at the bottom. Also on the top of the valve piston is often elastic element attached that damping the system at a stop like the socket already mentioned effect.

It is already known to use the valve piston at the top and bottom Grooves to be provided in which O-sealing or damping rings be placed. The punctures are mostly turned in costly. In addition, the assembly of the hard O-rings expensive. These are still at risk to fall out of their grooves under operational stress, whereby the device is damaged or unusable can be.

Proceeding from this, the object of the invention is in a driving tool of the type mentioned the Sealing the valve piston against the working cylinder and / or its damping relative to an upper stop improve.

This task is performed by a driving tool with the characteristics of claim 1 solved. Advantageous configurations are specified in dependent claims 2-15.

In the driving tool according to the invention, the positive connection or clawing of the sealing ring and / or the damping ring with the valve piston the seal or damping and the reliability of the device. In addition, the positive connection enables a reduction the effort for the manufacture of the valve piston and the placement of the sealing or damping ring. Of the Form locking is ensured by connecting webs which axial holes penetrate the valve piston and at one end with the sealing ring and at the other end with the damping ring are connected. The ring material form the connecting webs. Furthermore, the Sealing ring, the damping ring and the connecting webs in the Spraying methods are placed on the valve body, whereby as a material mainly thermoplastic elastomers in Come into consideration. Namely have thermoplastic elastomers the processing behavior of thermoplastics and in the cured Condition the elasticity of elastomers. Basically however come for sealing and / or damping ring other soft or elastic materials are also considered, e.g. POM. The injection point can be advantageous arranged for the ring material on the side of the damping ring be so that it seals against the working cylinder not affected.

Fig. 1

das Eintreibgerät im Längsschnitt;

Fig. 2

Ventilkolben des Eintreibgerätes vergrößert in der Draufsicht;

Fig. 3

derselbe Ventilkolben vergrößert im Querschnitt;

Fig. 4

derselbe Ventilkolben mit Dicht- und Dämpfungsring vergrößert im Querschnitt.

Further details and advantages of the invention will become apparent from the following description of an embodiment shown in the accompanying drawings. The drawings show:

Fig. 1

the driving tool in longitudinal section;

Fig. 2

Valve piston of the driving tool enlarged in plan view;

Fig. 3

the same valve piston enlarged in cross section;

Fig. 4

the same valve piston with sealing and damping ring enlarged in cross section.

1 has a housing 1, which in a housing head 2 has a working cylinder 3, in which a working piston 4 is arranged. The working piston 4 is connected to a plunger 5, which is in a Ejection channel 6 of a muzzle tool 7 is guided. On the side of the mouth tool 7 is a linear magazine 8 set for fasteners, the one Feed opening is connected to the discharge channel 6.

The housing 1 also has a handle 9 in which a Compressed air storage space 10 is provided, which has a Hose connection 11 can be connected to a compressed air source is. At the rear end, the handle 9 is over a bridge 12 connected to the magazine 8. There is also a locking lever 13, which is used to open and close the magazine 8 serves when refilling fasteners.

On the underside of the handle 9 is next to the housing head 2 a release lever 14 on a control valve carrier 15 stored. The control valve carrier 15 houses one Switch pin 16, the with a cylindrical portion Release lever 14 contacted and with a cone section concentric with one connected to the compressed air supply space 10 Sealing bush 17 is aligned in the housing 1. In the position shown gives the switching pin 16 with his Cone section the passage of the sealing bush 17 free, so that a cavity formed in the control valve carrier 15 18 is connected to the compressed air supply space. When pressed the release lever 14 by swiveling the Cone section moved into the opening of the socket 17, so that the aforementioned connection is interrupted. At the same time becomes one in a groove between the cone section and cylinder section Arranged O-ring seal (not shown) lifted from a sealing seat of the control valve carrier 15 and a connection in the area of the cylinder section 16 the cavity 18 released with the environment.

The cavity 18 is connected to a control channel which a tube 19 in crossing the compressed air storage space 10 a blind hole made from the bottom of the housing 20 has. The control channel has one with the blind hole 20 connected connecting channel 21, which is in a valve chamber 22 opens out, which is arranged above the working cylinder and over which there is a housing cap 23.

A valve piston 24 is arranged in the valve chamber 22 carries an O-ring 25 on the outer circumference. The valve piston 24 has an outer step 26 for supporting the O-ring on the inner circumference and on the top. The valve piston has at the top 24 a hollow cylindrical piston shoulder 27. Furthermore it is provided with a central through hole 28, which extends through the piston boss 27. The top has Drilled hole 28 an extension that a coil spring 29 records. The coil spring 29 is supported on the underside from a valve seat element 30, which in a Blind bore of the housing cap 23 is held.

The piston shoulder 27 is guided on the outside in a bush 31, the one for sealing against the piston shoulder inside O-ring 32 carries. The outside of the socket 31 is Another O-ring 33 on the inner wall of a screw connector sealed the housing cap 23 in the housing holds. At the top is the socket 31 at the bottom of the housing cap 23 supported. There it has radial outflow grooves 34. This communicate with radial outflow grooves 35 of the housing cap 23 connected to the environment.

The socket 31 is at the bottom at 36 with radially extending Provide ribs (not shown).

As can be seen better from FIGS. 2 and 3, the Valve piston 24 axial through holes 37, which are concentric arranged on its central axis outside around the piston shoulder 27 are. The axial through holes open at the Bottom 38 of the valve piston 24 in a rotating Ring groove 39 with a rectangular cross section. They lead to the Top 40 of the valve piston 24 in a rotating Annular groove 41 with a trapezoidal cross-section, which extends to Top 40 extended.

4 shows the through holes 37 and the grooves 39, 41 with an elastic sealing and Damping material filled, which one over the bottom 38 and the top 40 each protruding dome-shaped Sealing ring 42 and damping ring 43 with connecting webs 44 forms in the through holes 37.

The valve piston 24 is injection molded from a plastic. It can be a hard or impact-resistant material act, e.g. for a POM. The piston is sufficient firm to withstand the pressures that occur and permanently support the spring. The injection mold is divided at level 26. The Sealing and damping material is on the finished valve piston 24 injected. For example, a thermoplastic Elastomer used. The injection molding of the valve piston can be done after inserting in another tool. The injection point is preferably on the top 40.

As can be seen again from FIG. 1, this is the case formed sealing ring 42 the upper edge of the working cylinder 3 assigned to a counter sealing surface forms. The damping ring 43, however, acts with the ribs 36 together at the bottom of the socket 31.

The working cylinder 3 is approximately radial bores 45 a third of its height with a return air chamber surrounding it 46 connected. This is also via radial holes 47 at the lower end of the working cylinder its interior connected.

The device works as follows: In the starting position 1, the compressed air supply space 10 is over the cavity 18, the tube 20 and the connecting channel 21 connected to the valve chamber 22. Compressed air applied thus the upper side of the valve piston 24. At the same time it lies on the underside of the valve piston 24 in the area beyond the working cylinder 3. Because the pressure on the top effective area of the valve piston 24 supported by the coil spring 29 larger than that Is pressure on the lower effective area, the valve piston with the sealing ring 42 sealing against the upper Edge of the working cylinder 3 pressed. The working displacement is above the working piston 4 via the through hole 28 of the valve piston 24 and the radial outflow grooves 34, 35 connected to the environment and is thereby ventilated.

When the trigger lever 14 is actuated, the cavity 18 and thus the valve chamber 22 is connected to atmosphere. As a result only affects the lower effective area of the valve piston 24 compressed air, so that this against the Effect of the coil spring 29 in its upper open position is shifted by the application of the damping ring 43 defined on the radial ribs 36 of the socket 31 is. The upward piston movement is thus dampened. In the upper position is the valve piston 24 with the upper Edge of its piston shoulder 27 sealingly on the valve seat element 30 on. This will connect the working cubic space interrupted to the atmosphere. At the same time made possible the movement of the valve piston 24 flows upward of compressed air from the compressed air storage room 10 over the upper edge of the working cylinder 3 in the working stroke, so that the working piston 4 suddenly driven down becomes. The plunger 5 is one of the Magazine 8 refilled fastener through the muzzle tool 7 expelled.

After release of the release lever 14, this moves into his Starting position according to FIG. 1 back. As a result the upper effective area of the valve piston 24 again Compressed air applied. The cavities between the ribs 36 on the underside of the socket 31 ensure a spread the compressed air up to the piston boss 27. As a result the valve piston 24 is in its drawn lower Moved back to the closed position in which the sealing ring 42 seals against the upper edge of cylinder 3. Then the connection between compressed air storage space 10 and working displacement interrupted and the latter in turn with Atmosphere connected. Is in the lowest piston position Compressed air through the radial bores 45 into the return air chamber 46 streamed. The return air passes through others Radial bores 47 in the working space below the Working piston 4 ventilated on the upper side and drives it back to its starting position according to FIG. 1.

Then another can be operated by actuating the trigger 14 Driving process are triggered.

Claims (15)

1. A tacker for fastening means, with which an apparatus housing (1) comprises a valve space (22) of a main valve, which is closed by a housing cap (23) and in which a valve piston (24) is sealingly and slidingly guided coaxially above an operating cylinder (3), wherein the valve piston (24) in a lower position sealingly sits on the upper edge of the operating cylinder (3) and by way of this blocks an inlet channel, connected to a pressurised air source, to the upper operating stroke space, and in an upper position by way of a sealing bearing on a valve seat element (30) blocks an outlet channel which via a through-bore (28) of the valve piston is connected to the operating stroke space, wherein the valve piston (24) comprises a lower acting surface which is constantly impinged by pressure from the pressurised air source, and an upper acting surface which with the help of a control valve (15, 16, 17) is selectively impinged with atmospheric pressure or the pressure of the pressurised air source, characterised in that the valve piston (24) has axially directed through-bores (37), that connecting webs (44) are extended through the through-bores and that the connecting webs (44) at one end are connected to a sealing ring (42) on the lower side (38) and at the other end to a damping ring (43) on the upper side (40) of the valve piston (24).
2. A tacker according to claim 1, characterised in that the sealing ring (42) and/or the damping ring (43) protrudes somewhat beyond the lower side (38) and/or the upper side (40) of the valve piston (24).
3. A tucker according to claim 1 or 2, characterised in that the through-bores (37) widen towards the upper side (40) and/or lower side (38) of the valve piston (28).
4. A tucker according to one of the claims 1 to 3, characterised in that the sealing ring (42) and/or the damping ring (43) occupies only a fraction of the lower side (38) and/or upper side (40) of the valve piston (24).
5. A tacker according to one of the claims 1 to 4, characterised in that the valve piston (24) on the lower side (38) and/or the upper side (40) has shoulders (39, 41) laterally supporting the sealing ring (42) and/or the damping ring (43).
6. A tacker according to claim 5, characterised in that the distance between the shoulders (39, 41) increases towards the lower side (38) and/or to the upper side (40) of the valve piston (24).
7. A tacker according to claim 5 or 6, characterised in that the shoulders (39, 41) are lateral borderings of an annular groove (39, 42) in the lower side (38) and/or the upper side (40) of the valve piston (24).
8. A tacker according to one of the claims 1 to 7, characterised in that the sealing ring (42), the damping ring (43) and the connecting webs (44) are injected onto the valve piston (24).
9. A tacker according to one of the claims 1 to 8, characterised in that the sealing ring (42), the damping ring (43) and the connecting webs (44) are formed from the same material.
10. A tucker according to claim 8 or 9, characterised in that the sealing ring (42), the damping ring (43) and the connecting webs (44) are of a thermoplastic elastomer.
11. A tucker according to one of the claims 8 to 10, characterised in that the injection point of the sealing ring (42) and/or damping ring (43) is located on the upper side (40) of the valve body (24).
12. A tacker according to one of the claims 1 to 11, characterised in that the valve piston (24) above has a hollow cylindrical piston shoulder (27) through which the through-bore (28) of the valve piston runs, which is sealingly and slidingly guided in a sleeve (31) and which in the upper position sealingly bears on the valve seat element (30), and the sleeve (31) is an abutment for the damping ring (43) of the valve piston (24).
13. A tucker according to one of the claims 1 to 12, characterised in that the abutment (31) for the damping ring (43) of the valve piston (24) has radial ribs (36).
14. A tacker according to one of the claims 1 to 13, characterised in that the valve piston (24) on the outer circumference carries an O-sealing-ring (25).
15. A tacker according to claim 14, characterised in that the valve piston (24) comprises an outer step (26) for supporting the O-sealing-ring (25) on the inner circumference and on the upper side.

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