Compressed air nailer with safety actuator

Abstract

A compressed air nailer comprises a driving tappet connected to a compressed air supply and configured to drive in a fastener. A triggering apparatus is configured to trigger a driving process and a working piston is coupled to a driving tappet. A safety actuator is configured to be displaced between a locked position and an open position, wherein when in the locked position, the safety actuator is configured to inhibit the triggering of the driving process when an actuation of the triggering apparatus occurs. The compressed air nailer further comprises a throttle and a safety control chamber configured to be aerated and deaerated by the throttle. A counterforce generator is configured to generate a counterforce that acts on the safety actuator and is directed in an opposite direction from the actuating force. The counterforce is linearly dependent on an operating pressure of the compressed air nailer.

Claims

1. A compressed air nailer having an operating pressure and comprising: a driving tappet connected to a compressed air supply and configured to drive in a fastener; a triggering apparatus configured to trigger a driving process; a working piston coupled to the driving tappet, wherein compressed air is supplied when the driving process is triggered; a safety actuator configured to be moved between a locked position and an open position, wherein when in the locked position, the safety actuator is configured to inhibit the triggering of the driving process when an actuation of the triggering apparatus occurs; a throttle; a safety control chamber configured to be aerated and deaerated by the throttle, wherein a pressure in the safety control chamber exerts an actuating force on the safety actuator; and a counterforce generator configured to generate a counterforce that acts on the safety actuator and is directed in an opposite direction from the actuating force, wherein the counterforce is linearly dependent on the operating pressure, and wherein the counterforce is configured to move the safety actuator into the locked position.

2. The compressed air nailer according to claim 1, wherein the counterforce is from 10% to 90% of an actuating force when the operating pressure prevails in the safety control chamber.

3. The compressed air nailer according to claim 1, wherein the counterforce generator comprises a control space, and wherein a pressure in the control space acts on the safety actuator.

4. The compressed air nailer according to claim 3 wherein the pressure in the safety control chamber acts on a first effective surface of the safety actuator and the pressure in the control space acts on a second effective surface of the safety actuator, and wherein the second effective surface is smaller than the first effective surface.

5. The compressed air nailer according to claim 4, wherein the second effective surface is from 10% to 90% of a size of the first effective surface.

6. The compressed air nailer according to claim 3, wherein the operating pressure prevails in the control space when the compressed air nailer is connected to the compressed air supply.

7. The compressed air nailer according to claim 1, further comprising a spring configured to exert an additional force on the safety actuator.

8. The compressed air nailer according to claim 1, wherein the triggering apparatus comprises: a trigger; and a placing sensor, wherein jointly actuating the trigger and the placing sensor acts to control a first control valve and trigger the driving process, and wherein the safety actuator is configured to release a mechanical engagement between the triggering apparatus and the first control valve when in the locked position.

9. The compressed air nailer according to claim 1, further comprising a first control line, wherein aeration or deaeration of the first control line triggers the driving process, and wherein the safety actuator is configured to block a connecting line between the first control line and the triggering apparatus when the safety actuator is in a lock position.

10. The compressed air nailer according to claim 1, wherein the triggering apparatus comprises: a trigger; and a placing sensor, wherein jointly actuating the trigger and the placing sensor acts to control a first control valve and trigger the driving process if the pressure in the safety control chamber is above a given pressure threshold.

11. The compressed air nailer according to claim 10, further comprising a second control valve configured to be controlled independent of an actuation of the placing sensor when the trigger is actuated, wherein the safety control chamber is continuously deaerated by the throttle independent of the position of the second control valve, and wherein the safety control chamber is separated from a housing interior, and wherein the housing interior is under pressure when the second control valve is controlled.

12. The compressed air nailer according to claim 11, wherein the throttle comprises an opening cross-section dimensioned such that the actuating force falls below the counterforce after an expiration of a period within a range of from 1 second to 10 seconds after the second control valve is controlled.

13. The compressed air nailer according to claim 12, further comprising a non-return valve configured to aerate the safety control chamber when the driving process is triggered.

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 partial cross-sectional view of an embodiment of a compressed air nailer;

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

(4) FIG. 3 illustrates an enlarged view of the embodiment of FIG. 1 in an operating state;

(5) FIG. 4 illustrates an enlarged view of the embodiment of FIG. 1 in another operating state;

(6) FIG. 5 illustrates an enlarged view of the embodiment of FIG. 1 in another operating state; and

(7) FIG. 6 illustrates an enlarged view of the embodiment of FIG. 1 in yet another operating state.

DETAILED DESCRIPTION OF THE INVENTION

(8) 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.

(9) 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.

(10) 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.

(11) 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. It is retained in this position by the force of a spring 102.

(12) 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 shown 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 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.

(13) 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.

(14) A driving process is triggered by aerating the first 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. Below the pilot valve 58, there is a triggering apparatus which is covered in FIG. 1 by a surface surrounded by a dashed line. Details of the triggering apparatus will be explained in greater detail with reference to FIGS. 3 to 6.

(15) It can be seen in these figures that the trigger 14 is rotatably mounted about a pivot axis 16 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 18 which displaces a switching pin 20 of a second control valve 22 upward upon an actuation of the trigger 14. This control of the second control valve 22 occurs upon each actuation of the trigger 14 independent of the position of the placing sensor 24.

(16) The force transmission element 30 of the placing sensor 24 is movably guided on the housing of the compressed air nailer 10 and has a slot 32 through which a guide pin 98 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 36, the fixed end of which is pivotably articulated about a pivot axis 38 in the interior of the trigger 14 and close to its free end. The rocker 36 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 switching pin 42 of a first control valve 44 upward and thus controls the first control valve 44.

(17) At the top left in FIG. 3, the first control line 82 is discernible which runs to the pilot valve 58. A safety actuator 34 is shown below the first control line 82 which performs a valve function. The safety actuator 34 can be displaced between an open position and a closed position. It is drawn in its open position in FIG. 3.

(18) The safety actuator 34 is guided in a sleeve 66 and has a middle section 68. In the region of the middle section 68, the sleeve 66 has a radial bore 60. At the lower end of the middle section 68, the safety actuator 34 has a lower piston section 74 which is sealed by an O-ring 76 against a cylindrical space. The part of this cylindrical space arranged below the piston section 74 forms a safety control chamber 62. The pressure prevailing in the safety control chamber 62 exerts an actuating force on the lower piston section 74 and thereby on the safety actuator 34 and attempts to displace it into its open position, or respectively to hold it therein. The safety control chamber 62 is connected to external air via a throttle 86.

(19) At the upper end of the middle section 68, the safety actuator 34 has an upper piston section 78 which is also guided in a cylindrical chamber and is sealed against the cylindrical space by an O-ring 80. The upper piston section 78 is made as a separate part and adjoins the lower piston section 74. The part of the cylindrical space arranged above the upper piston section 78 forms a control space 84 which is continuously connected to a housing interior 64. Once the compressed air nailer 10 is connected to a compressed air supply, the housing interior 64 is aerated. The operating pressure prevailing in the control space 84 thereby exerts a counterforce on the upper piston section 78 and hence on the safety actuator 34. This counterforce is directed in the opposite direction of the actuating force and attempts to displace the safety actuator 34 into its locked position.

(20) When the trigger 14 is in the non-actuated state shown in FIG. 3, the second control valve 22 is not actuated. The two O-rings 90, 92 of the second control valve 22 do not provide a seal so that a line 124 running to the first control valve 44 is connected to the housing interior 64 via the second control valve 22. Independent of the position of the first control valve 44, the air flows from the line 124 through an annular gap 126 that surrounds a sleeve 88 of the second control valve 44 and a bore 128 into the safety control chamber 62. Because the amount of air simultaneously escaping through the throttle 86 is negligible in comparison to this inflow, substantially the operating pressure always prevails in the initial state in the safety control chamber 62.

(21) In this case, the actuating force exerted on the safety actuator 34 by the pressure in the safety control chamber 62 is greater than the counterforce exerted by the operating pressure in the control space 84. The safety actuator 34 therefore remains in its open position. In this open position, the first control line 82 is connected to a line 134 running to the first control valve 44 via a radial bore 132 in the middle section 68 of the safety actuator 34 and an annular gap 130, as well as the radial bore 68 in the sleeve 66. Since an O-ring 136 of the first control valve 44 does not provide a seal when the first control valve 44 is in the unactuated position, the line 134 is connected via the first control valve 44 to external air. At the same time, the O-ring 138 of the first control valve 44 provides a seal and separates the line 134 from the housing interior 64.

(22) In FIG. 4, the trigger 14 has been actuated, and the second control valve 22 along with it. It can be seen that the control pin 20 of the second control valve 22 has been displaced upward. The O-ring 90 now provides a seal and separates the housing interior 64 from the line 124. This ends the air supply to the safety control chamber 62 so that the pressure in the safety control chamber 62 slowly decreases by the air escaping through the throttle 86. The O-ring 92 also provides a seal. It prevents a leakage flow to the line 124 when the O-ring 90 is leaky. Instead, such a leakage flow is discharged outward via the cross bore 146 located between the two O-rings 90, 92 in the valve pin 20. Another O-ring 158 of the second control valve 22 still provides a seal, so that the line 124 is separated from the external air when the second control valve 22 is actuated.

(23) If, starting from the situation in FIG. 4, the placing sensor 24 is actuated within a short time span, the force transmission element 30 assumes the position shown in FIG. 5 and entrains the rocker 36 upward so that the switching pin 42 of the first control valve 44 is displaced upward and the first control valve 44 is actuated. The O-ring 136 then moves into a seal, whereas the O-ring 138 releases the seal. The housing interior 64 is thus connected via the radial bore 144 to the line 134, which effectuates an aeration of the first control line 82 and hence a triggering of a driving process.

(24) Another effect of aerating the line 134 is that the safety control chamber 62 is aerated via the annular gap 130, the radial bore 132 and an axial bore 148 that extends in the middle through the safety actuator 34 over a majority of the length, as well as through another radial bore 150 in the safety actuator 34 and the O-ring 152 acting as a non-return valve. The pressure in the safety control chamber 62 is also refreshed so that the period in which an additional contact triggering is possible starts to run again.

(25) If there is no actuation of the placing sensor 24 within this period, the pressure in the safety control chamber 62 finally decreases enough for the counterforce to overcome the actuating force, and the safety actuator 34 assumes its locked position. This is shown in FIG. 6. If the placing sensor 24 and the first control valve 44 along with it are then re-actuated, the line 134 is again aerated. Due to the two O-rings 154, 156 providing a seal on the middle section 68 of the safety actuator 34, this however remains unsuccessful. In the locked position, the safety actuator 34 blocks the line 134 both from the first control line 82 as well as from the safety control chamber 62. Another driving process can therefore only be triggered again when the trigger 14 is released and the pressure in the safety control chamber 62 is restored by the second control valve 22 so that the safety actuator is displaced into its open position.

(26) List of Reference Numbers

(27) 10 Compressed air nailer 12 Handle 14 Trigger 16 Pivot axis 18 Switching surface 20 Switching pin 22 Second control valve 24 Placing sensor 26 Mouth 28 Outlet tool 30 Force transmission element 32 Slot 34 Safety actuator 36 Rocker 38 Pivot axis 40 Switching surface 42 Switching pin 44 First control valve 46 Receiver 48 Magazine 50 Driving tappet 52 Working piston 54 Working cylinder 56 Main valve 58 Pilot valve 60 Radial bore 62 Safety control chamber 64 Housing interior 66 Sleeve 68 Middle section 70 Annular gap 72 Space 74 Lower piston section 76 O-ring 78 Upper piston section 80 O-ring 82 First control line 84 Control space 86 Throttle 88 Sleeve 90 O-ring 92 O-ring 94 Control piston 96 Guide sleeve 98 Guide pin 100 Lower O-ring 102 Spring 104 Central O-ring 106 Upper O-ring 110 Main control line 112 Radial bore 114 Space 116 Main valve actuating member 118 O-ring 120 Spring 122 Annular surface 124 Line 126 Annular gap 128 Bore 130 Annular gap 132 Radial bore 134 Line 136 O-ring 138 O-ring 140 O-ring 142 Housing cap 144 Radial bore 146 Cross bore 148 Axial bore 150 Radial bore 152 O-ring 154 O-ring 156 O-ring 158 O-ring