Compressed air nailer with safety valve arrangement

Abstract

A compressed air nailer comprises a control line configured to trigger a driving process when a valve pin is displaced relative to a valve sleeve into an actuated position. The valve sleeve is configured to move between a triggering position and a locked position. A switching surface is coupled to at least one of a trigger and a placing sensor and configured to actuate the valve pin. An outer sleeve is configured to guide the valve sleeve. The switching surface is positioned at a switching surface position relative to the outer sleeve when both the trigger and the placing sensor are actuated. The switching surface is configured to displace the valve pin into the actuated position when the valve sleeve is positioned in the triggering position. The switching surface does not displace the valve pin into the actuated position when the valve sleeve is positioned in the locked position.

Claims

1. A compressed air nailer comprising: a working piston; a driving tappet coupled to the working piston and configured for driving in a fastening means during a driving process, wherein compressed air is applied when the driving process is triggered; a trigger valve comprising a valve sleeve and a valve pin configured to be guided within the valve sleeve; a control line configured to be one of aerated and deaerated by the trigger valve, wherein the one of aeration and deaeration of the control line is configured to trigger the driving process when the valve pin is displaced relative to the valve sleeve into an actuated position; a trigger; a placing sensor; a switching surface coupled to at least one of the trigger and the placing sensor, the switching surface configured to actuate the valve pin; an outer sleeve configured to at least partially surround and guide the valve sleeve; a safety control chamber, wherein a pressure within the safety control chamber is configured to displace the valve sleeve relative to the outer sleeve between a triggering position and a locked position; and a safety control valve configured to be controlled by the trigger, wherein the safety control valve controls the one of the aeration and deaeration of the safety control chamber, wherein, when the switching surface is located in a switching surface position relative to the outer sleeve, actuation of both the trigger and the placing sensor result in displacement of the switching surface, wherein the switching surface is positioned in the switching surface position such that the switching surface displaces the valve pin into the actuated position when the valve sleeve is positioned in the triggering position, and wherein the switching surface does not displace the valve pin into the actuated position when the valve sleeve is positioned in the locked position, wherein when the trigger is actuated, the trigger contacts and displaces the safety control valve such that a connection between the safety control chamber and an aerated housing interior is blocked by the safety control valve.

2. The compressed air nailer according to claim 1, wherein the safety control chamber is connected via a throttle to external air.

3. The compressed air nailer according to claim 2, wherein the switching surface is formed on a rocker that includes a fixed end and a free end, wherein the fixed end is rotatably mounted on the trigger, and wherein the free end is entrained by the placing sensor upon an actuation of the placing sensor.

4. The compressed air nailer according to claim 2, wherein the switching surface is formed on the placing sensor and is at a fixed position relative to the placing sensor.

5. The compressed air nailer according to claim 4, wherein the safety control valve and the trigger valve are series-connected.

6. The compressed air nailer according to claim 5, wherein the safety control chamber is at least one of aerated and deaerated by the trigger valve and a non-return valve when the valve pin is displaced relative to the valve sleeve into the actuated position.

7. The compressed air nailer according to claim 6, wherein the non-return valve is integrated into the valve sleeve.

8. The compressed air nailer according to claim 1, wherein the safety control chamber defines an annular space that is delimited by two seals positioned between the outer sleeve and the valve sleeve, and wherein the two seals are spaced apart from each other in an axial direction and a radial direction.

9. The compressed air nailer according to claim 1, further comprising a counterpressure chamber that is continuously aerated, wherein a pressure inside the counterpressure chamber exerts a counterforce on the valve sleeve in a direction opposite a force exerted on the valve sleeve by the pressure in the safety control chamber.

10. The compressed air nailer according to claim 9, wherein the counterpressure chamber defines an annular space that is delimited by two seals abutting the valve sleeve, and wherein the two seals are spaced from each other in an axial direction and a radial direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in greater detail below with reference to an exemplary embodiment shown in figures. In the figures:

(2) FIG. 1 illustrates a cross-sectional view of an embodiment of a compressed air nailer;

(3) FIG. 2 illustrates an enlarged view of an embodiment of a main valve and a pilot valve of the embodiment of the compressed air nailer of FIG. 1;

(4) FIG. 3 illustrates an embodiment of a trigger, trigger valve, and a safety control valve of the air nailer of FIG. 1 in an operating state;

(5) FIG. 4 illustrates the embodiment of a trigger, trigger valve, and a safety control valve of the air nailer of FIG. 1 in another operating state;

(6) FIG. 5 illustrates the embodiment of a trigger, trigger valve, and a safety control valve of the air nailer of FIG. 1 in another operating state;

(7) FIG. 6 illustrates the embodiment of a trigger, trigger valve, and a safety control valve of the air nailer of FIG. 1 in another operating state; and

(8) FIG. 7 illustrates the embodiment of a trigger, trigger valve, and a safety control valve of the air nailer of FIG. 1 in still another operating state.

DETAILED DESCRIPTION OF THE INVENTION

(9) Initially, a few important elements of the compressed air nailer 10 will be described, some summarily, with reference to FIG. 1. The compressed air nailer 10 has a handle 12 that is attached to a lower housing part 140 which is closed at the top by a housing cap 142.

(10) The compressed air nailer 10 has a placing sensor 24 that projects downward a few millimeters beyond the mouth 26 of an outlet tool 28. If the compressed air nailer 10 is placed onto a workpiece, the placing sensor 24 is displaced upward against the force of a spring (not shown) until it abuts the mouth 26 flush or projects just slightly above the mouth 26. The placing sensor 24 is mechanically coupled to a force transmission element 30 which also moves upward when the placing sensor 24 moves.

(11) The outlet tool 28 has a receiver 46, in each case a fastening means being supplied thereto from a magazine 48. From this position inside the receiver 46, the fastening means, for example a nail, a tack or a staple, is driven in by a driving tappet 50 which is connected to a working piston 52 of the compressed air nailer 10. To this end, the working piston 52 is guided in a working cylinder 54. Above the working cylinder 54 and sealingly closing this working cylinder, a main valve 56 is arranged, to the right thereof being a pilot valve 58 which controls the main valve 56. Details of these elements as well as the associated function of the device will be explained with reference to the enlargement of a section in FIG. 2.

(12) The pilot valve 58 is best discernible in FIG. 2. It has a control piston 94 which is guided in a guide sleeve 96. The lower end of the control piston 94 is sealed by a lower O-ring 100 relative to the guide sleeve 96. In the initial state of the compressed air nailer 10, a first control line 82 which is connected to a working volume of the pilot valve 58 is deaerated, and the control piston 94 is located in the shown lower position. In this position, the control piston is retained by the force of a spring 102.

(13) The control piston 94 has, in addition to the lower O-ring 100, a central O-ring 104 and an upper O-ring 106. In the depicted lower position of the control piston 94, the upper O-ring 106 seals the control piston 94 against the guide sleeve 96 and closes a connection to a deaeration opening (not shown) connected to the external air. The central O-ring 104 is not sealed, so that a main control line 110 is connected to the housing interior 64 via a radial bore 112 in the guide sleeve 96 and the annular gap 70 between the control piston 94 and guide sleeve 96 running past the central O-ring 104. The main control line 110 is connected via a connection, which is invisible in the depicted sectional plane, to the space 72 that terminates in the radial bore 112. The housing interior 64 in the initial state of the compressed air nailer 10 is aerated, i.e. connected to a compressed air connection, not shown, and at operating pressure.

(14) The main control line 110 is connected to a space 114 above a main valve actuating member 116 of the main valve 56 such that the main valve actuating member 116 is subjected to a downward force which seals the upper edge of the working cylinder 54 by means of an O-ring 118 against the housing interior 64. Additionally, the main valve actuating member 116 is acted upon by a spring 120 with a force in the direction of the position shown, closing the working cylinder 54.

(15) A driving process is triggered by aerating the control line 82 in that the control piston 94 is displaced upward so that the central O-ring 104 creates a seal and the upper O-ring 106 releases the seal. This blocks the connection of the main control line 110 to the housing interior 64, and a connection between the main control line 110 and a deaeration opening (not shown) is established. The space 114 above the main valve actuating member 116 is deaerated via the deaeration opening, and the main valve actuating member 116 is displaced upwardly counter to the force of the spring 120 by the pressure which is present on its lower outer annular surface 122 and which prevails in the housing interior 64. As a result, compressed air flows out of the housing interior 64 into the working cylinder 54 above the working piston 52 and drives the working piston 52 downwardly. With this downward movement, the driving tappet 50 connected to the working piston 52 drives in a fastening means.

(16) As summarily discernible in FIG. 1, a triggering apparatus with a trigger valve 22, a safety control valve 16 and a trigger 14 is located below the pilot valve 58. Details of the triggering apparatus will be explained in greater detail with reference to FIGS. 3 to 7.

(17) It can be seen in these figures that the trigger 14 is rotatably mounted about a pivot axis 18 in an easy-to-grip position on the housing of the compressed air nailer 10. The upper, rear end of the trigger 14 has a switching surface 20 which displaces a valve pin 32 of the safety control valve 16 upward upon an actuation of the trigger 14. This control of the safety control valve 16 occurs upon each actuation of the trigger 14 independent of the position of the placing sensor 24.

(18) The force transmission element 30 of the placing sensor 24 is movably guided on the housing of the compressed air nailer 10 and to this end has a slot 34 through which a guide pin 36 is guided. Upon an actuation of the placing sensor 24, the force transmission element 30 is displaced upward from the starting position drawn in FIG. 3, and in so doing entrains the free end of a rocker 38, the fixed end of which is pivotably articulated about a pivot axis 41 in the interior of the trigger 14 and close to its free end. The rocker 38 is then arranged approximately parallel to a longitudinal direction of the trigger 14, and its upper side functions as a switching surface 40 which, given the joint actuation of the placing sensor 24 and the trigger 14, displaces a valve pin 42 of the trigger valve 22 upward and thus controls the trigger valve 22.

(19) The trigger valve 22 has a valve sleeve 44 in which the valve pin 42 is guided. For its part, the valve sleeve 44 is guided in an outer sleeve 60 fixedly arranged relative to the handle 12. In FIG. 3, the valve sleeve 44 is located in a triggering position relative to the outer sleeve 60. In this triggering position that corresponds to an initial state of the compressed air nailer 10, the valve sleeve 44 is retained by pressure in a safety control chamber 62, which is aerated when the safety control valve 16 is not actuated. The force exerted on the valve sleeve 44 by the pressure in the safety control chamber 62 is greater than a counterforce exerted on the valve sleeve 44 by the pressure in the counterpressure chamber 66. The counterpressure chamber 66 is always connected to the housing interior 64 by a connection (not shown) and is therefore always aerated when the compressed air nailer 10 is connected to a compressed air supply.

(20) The counterpressure chamber 66 surrounds a lower region of the valve sleeve 44 in a ring. It is delimited by an upper seal 74 and a lower seal 76 that produce a seal relative to the valve sleeve 44, wherein the upper seal 74 and lower seal 76 are spaced from each other in an axial direction and radial direction. The upper seal 74 is an O-ring inserted in a peripheral groove in the valve sleeve 44 which abuts the inside of the outer sleeve 60. The lower seal 76 is an O-ring inserted in a peripheral groove of a lock washer 84 which is inserted sealingly in a valve block 68 and abuts the outside of the valve sleeve 44. In a radial direction further to the outside, the counterpressure chamber 66 comprises a gap between the lock washer 84 and the outer sleeve 60. There, two additional seals 148 and 150 provide a seal of the counterpressure chamber 66 against the housing in which the outer sleeve 60 and lock washer 84 are inserted.

(21) The safety control chamber 62 also has an annular space which is delimited by an upper seal 78 and lower seal 80. These two seals 78, 80 are also spaced from each other in a radial and axial direction and arranged between the valve sleeve 44 and the outer sleeve 60. The safety control chamber 62 is connected by an axial bore 152 in the outer sleeve 60, a ring gap 154 and a bore 156 in the housing to a throttle 86 through which a slight air stream continuously escapes when the safety control chamber 62 is aerated. Nonetheless, the operating pressure prevails in the safety control chamber 62 in the initial state shown in FIG. 3 since the safety control chamber 62 is simultaneously connected by a radial bore 88 in the outer sleeve 60 to a safety control line 90 which is connected to the housing interior 64 by the safety control valve 16. It is discernible in FIG. 3 that the two O-rings 124, 126 of the safety control valve 16 do not provide a seal so that the connection between the safety control line 90 and the housing interior 64 is opened via a radial bore 92 in a valve sleeve 98 of the safety control valve 16.

(22) In the initial position of the trigger valve 22 shown in FIG. 3, the valve pin 42 is in an unactuated position relative to the valve sleeve 44 in which an upper O-ring 128 arranged on the valve pin 42 provides a seal, and a lower O-ring 130 arranged on the valve pin 42 does not provide a seal. Consequently, the control line 82 is connected to external air by a radial bore 132 in the outer sleeve 60, a radial bore 134 in the valve sleeve 44, and an annular gap 108 between the valve pin 42 and valve sleeve 44.

(23) The valve sleeve 44 has another radial bore 144 that is sealed by an O-ring 146 arranged in a groove running around the outside of the valve sleeve 44. This arrangement with the O-ring 146 forms a non-return valve by means of which the safety control chamber 62 can be aerated by the trigger valve 22.

(24) Starting from the initial state from FIG. 3, if the trigger 14 is actuated, the arrangement shown in FIG. 4 results. The switching surface 20 of the trigger 14 has displaced the valve pin 32 upward and thereby actuated the safety control valve 16. The two O-rings 124 and 126 now provide a seal so that the connection of the safety control line 90 to the housing interior 64 is blocked. Consequently, the pressure in the safety control chamber 62 gradually decreases via the throttle 86. Until a given pressure threshold in the safety control chambers 62 is undershot, the valve sleeve 44 remains in its triggering position.

(25) If the compressed air nailer 10 is now placed onto a workpiece, the arrangement portrayed in FIG. 5 results, and the following occurs: The placing sensor 24 is actuated, and the force transmission element 30 of the placing sensor 24 entrains the free end of the rocker 38 on its path upward so that the switching surface 40 formed on the upper side of the rocker 38 reaches its switching position, which is always arranged in the same position relative to the outer sleeve 60 and is always set when both the trigger 14 as well as the placing sensor 24 are actuated. The valve pin 42 of the trigger valve 22 is displaced into its actuated position relative to the valve sleeve 44. This moves the lower O-ring 130 into a seal, whereas the upper O-ring 128 moves out of the seal. Compressed air from the housing interior 64 flows past the upper O-ring 128 through the radial bore 134 in the valve sleeve 44 and through the radial bore 132 in the outer sleeve 60 into the control line 82, which triggers a driving process. At the same time, the pressure in the safety control chamber 62 is refreshed by the air flowing past the upper O-ring 128 through the non-return valve formed by the other radial bore 144 and the O-ring 146.

(26) If, after the trigger 14 is actuated corresponding to FIG. 4, the placing sensor 44 is not actuated for a time period of e.g. four seconds or longer, and the pressure in the safety control chamber 62 consequently drops below a given pressure threshold, the valve sleeve 44 is displaced relative to the outer sleeve 60 into its locked position shown in FIG. 6. In this case, the control line 82 remains still connected to external air by the path explained with reference to FIG. 3.

(27) If, starting from this situation, the placing sensor 24 is actuated, the rocker 38 and the switching surface 40 along with it also reach their switching position precisely as explained with reference to FIG. 5. However, this does not cause a driving process to be triggered because the valve sleeve 44 is in its locked position relative to the outer sleeve 60, i.e., withdrawn into the interior of the handle 12, or respectively the valve block 68 in comparison to its triggering position in the direction of actuation of the valve pin 42. Consequently, the switching surface 40 cannot actuate the trigger valve 22 despite reaching its switching position. Another driving process can only be triggered when the trigger 14 has been released for a short time which leads to an aeration of the safety control chamber 62 and hence a displacement of the valve sleeve 44 into its triggering position.

LIST OF REFERENCE NUMBERS USED

(28) 10 Compressed air nailer 12 Handle 14 Trigger 16 Safety control valve 18 Pivot axis 20 Switching surface 22 Trigger valve 24 placing sensor 26 Mouth 28 Outlet tool 30 Force transmission element 32 Valve pin of the safety control valve 34 Slot 36 Guide pin 38 Rocker 40 Switching surface 41 Pivot axis 42 Valve pin 44 Valve sleeve 46 Receiver 48 Magazine 50 Driving tappet 52 Working piston 54 Working cylinder 56 Main valve 58 Pilot valve 60 Outer sleeve 62 Safety control chamber 64 Housing interior 66 Counterpressure chamber 68 Valve block 70 Annular gap 72 Space 74 Upper seal 76 Lower seal 78 Upper seal 80 Lower seal 82 Control line 84 Lock washer 86 Throttle 88 Radial bore in the outer sleeve 90 Safety control valve 92 Radial bore 94 Control piston 96 Guide sleeve 98 Valve sleeve 100 Lower O-ring 102 Spring 104 Central O-ring 106 Upper O-ring 108 Annular gap 110 Main control line 112 Radial bore 114 Space 116 Main valve actuating member 118 O-ring 120 Spring 122 Annular surface 124 O-ring of the safety control valve 126 O-ring of the safety control valve 128 Upper O-ring of the trigger valve 130 Lower O-ring of the trigger valve 132 Radial bore in the outer sleeve 134 Radial bore in the valve sleeve 140 Lower housing part 142 Housing cap 144 Additional radial bore of the valve sleeve 146 O-ring 148 Additional seal 150 Additional seal 152 Bore 154 Annular gap 156 Bore