Compressed air nail gun with a safety device

Abstract

The invention relates to a pneumatic nailer having a working piston and a common actuation that is configured to trigger a drive-in process which has a control volume and which is designed to automatically undertake a safety measure when a pressure threshold in the control volume is exceeded or not met. The control volume is ventilated or vented via a throttle such that a delay time, after the expiration of which the pressure threshold is exceeded or not met, is specified by a volume of the control volume and an opening cross-section of the throttle. The control volume has a volume in the range from 0.5 ml to 20 ml and the throttle is a bore having a diameter in the range from 30 m to 200 m.

Claims

1. A compressed air nail gun, comprising: a working piston which is connected to a driving ram for driving in a fastening means and to which compressed air is applied when a drive-in process is triggered; a trigger and a contact sensor, a common actuation is configured to trigger a drive-in process; and a safety device which has a control volume and is designed to automatically take a safety measure when a pressure threshold is exceeded or undercut in the control volume, wherein the control volume is aerated or deaerated via a throttle in such a way that a delay time, after the expiry of which the pressure threshold is exceeded or undercut, is specified by a volume of the control volume and an opening cross-section of the throttle, wherein the control volume has a volume in the range of 0.5 ml to 20 ml and the throttle is a borehole with a diameter in the range of 30 m to 95 m, the borehole arranged in a replaceable component of the compressed air nail gun, the replaceable component being a valve sleeve.

2. The compressed air nail gun according to claim 1, wherein the borehole is produced by laser drilling.

3. The compressed air nail gun according to claim 1, wherein the borehole has a length in the range of 30 m to 1 mm.

4. The compressed air nail gun according to claim 1, wherein the compressed air nail gun has a first control valve, which is actuated with each actuation of the trigger, wherein the control volume is aerated or deaerated via the first control valve.

5. The compressed air nail gun according to claim 1, wherein the compressed air nail gun has a second control valve, which is actuated with each actuation of the contact sensor or with each common actuation of trigger and contact sensor, wherein a main control line is aerated and/or deaerated via the second control valve.

6. The compressed air nail gun according to claim 1, wherein the control volume comprises an annular volume which surrounds a control valve.

7. The compressed air nail gun according to claim 1, wherein the compressed air nail gun comprises a housing which has a recess in which a control valve arrangement is arranged, wherein the control volume is arranged in full or in large part in the recess.

8. The compressed air nail gun according to claim 1, wherein the safety measure is that the compressed air nail gun is moved to a locked state in which no drive-in process can be triggered.

9. The compressed air nail gun according to claim 1, wherein the compressed air nail gun is configured to operate in a contact triggering operation and in a single triggering operation and the safety measure is that the compressed air nail gun is moved from the contact triggering operation to the single triggering operation.

10. The compressed air nail gun according to claim 1, wherein the compressed air nail gun has a locking sleeve, which is movable between a locked position and an open position, wherein the locking sleeve shuts off a connection between a main control line and a control valve in the locked position and opens it in the open position.

11. The compressed air nail gun according to claim 10, wherein a pressure in the control volume is applied to the locking sleeve.

12. A compressed air nail gun, comprising: a working piston which is connected to a driving ram for driving in a fastening means and to which compressed air is applied when a drive-in process is triggered; a trigger and a contact sensor, a common actuation is configured to trigger a drive-in process; and a safety device which has a control volume and is designed to automatically take a safety measure when a pressure threshold is exceeded or undercut in the control volume, wherein the control volume is aerated or deaerated via a throttle in such a way that a delay time, after the expiry of which the pressure threshold is exceeded or undercut, is specified by a volume of the control volume and an opening cross-section of the throttle, wherein the control volume has a volume in the range of 0.5 ml to 20 ml and the throttle is a borehole with a diameter in the range of 30 m to 95 m and the compressed air nail gun has a locking sleeve, which is movable between a locked position and an open position, wherein the locking sleeve shuts off a connection between a main control line and a control valve in the locked position and opens it in the open position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in more detail below with reference to two exemplary embodiments represented in the figures. In the drawings is shown:

(2) FIG. 1 compressed air nail gun with a control valve arrangement shown in cross-section and further elements represented only schematically,

(3) FIG. 2 the control valve arrangement from FIG. 1 in an enlarged representation,

(4) FIG. 3 the control valve arrangement from FIG. 1 after actuation of the contact sensor,

(5) FIG. 4 the control valve arrangement from FIG. 1 after actuation of the trigger,

(6) FIG. 5 the control valve arrangement from FIG. 1 after removing the compressed air nail gun from a workpiece,

(7) FIG. 6 the control valve arrangement from FIG. 1 after expiry of a delay time,

(8) FIG. 7 a control valve arrangement of a further compressed air nail gun in cross-section,

(9) FIG. 8 the control valve arrangement from FIG. 7 after actuation of the trigger,

(10) FIG. 9 the control valve arrangement from FIG. 7 after actuation of the contact sensor and

(11) FIG. 10 the control valve arrangement from FIG. 7 after removing the compressed air nail gun from a workpiece.

DESCRIPTION OF THE INVENTION

(12) The compressed air nail gun from FIG. 1 comprises a working piston 10, which is connected to a driving ram 12. The working piston 10 is displaceably mounted in a working cylinder 14. If compressed air is applied above the working piston 10, a fastening means, not represented, can be driven into a workpiece with the driving ram 12. A main valve 16 is located above the working cylinder 14, which is responsible for supplying the working cylinder 14 with compressed air from a compressed air reservoir, not represented, inside the compressed air nail gun or by a compressed air connection. The main valve 16 is actuated by a pilot valve 18. In turn, the pilot valve 18 is actuated by a main control line 20. As soon as the main control line 20 is aerated, the pilot valve 18, and subsequently the main valve 16, switches and a drive-in process is triggered.

(13) All the elements of FIG. 1 mentioned thus far are only represented schematically. A specific configuration of these elements can, for example, be inferred from FIGS. 1 and 2 of document WO 2019/038124 A1 as well as the corresponding description therein. The design described in the document is suitable for use with the invention.

(14) The elements represented in FIG. 1 in the cross-section, which are collectively referred to as control valve arrangement, are important for the understanding of the invention. They are responsible for controlling the pressure in the main control line 20 and thus for triggering drive-in processes. These elements include a first control valve 22, a second control valve 24, a trigger 26 and a contact sensor 28. In the cross-sectional representation of FIG. 1, only one upper end of the contact sensor 28 is shown. The contact sensor 24 also comprises a lower end 104, which in FIG. 1 is represented schematically and protrudes over an opening of an outlet tool not represented. Details on the control valve arrangement will be explained further with reference to the enlarged representation of FIG. 2.

(15) FIG. 2 shows the control valve arrangement in an initial state of the compressed air nail gun, in which trigger 26 and contact sensor 28 are not actuated and the compressed air nail gun is correctly connected to a compressed air source. The housing interior 32 (which is also only partially represented) arranged inside the housing 30, which can only be recognised in sections, is then continuously under operating pressure. The housing 30 merges, on the right edge of FIG. 2, into a handle section 34 of the compressed air nail gun.

(16) The trigger 26 is pivotably mounted on the housing 30 about an axis 36 fixed to the housing. At its rear end, it has an actuating surface 38 by means of which a valve pin 40 of the first control valve 22 is movable. The rear end of the contact sensor 28 interacts with a contact sensor lever 42 arranged partially inside a recess of the trigger 26. At the rear end, the contact sensor lever 42 is pivotably mounted on the housing 30 about an axis 44 fixed to the housing. The front end of the contact sensor lever 42 is entrained by the rear end of the contact sensor 28 when the contact sensor 28 moves upwards relative to the housing 30 when the compressed air nail gun is placed on a workpiece. As a result, an actuating surface 46 of the contact sensor lever 42 moves a valve pin 48 of the second control valve 24 upwards.

(17) The first control valve 22 comprises a lower valve sleeve 50 and an upper valve sleeve 52. A small borehole 54 is arranged in the transverse direction in the lower valve sleeve 50. This borehole 54 has a diameter of about 70 m and a length of about 200 m. Due to these very small dimensions, the borehole 54 in FIG. 2 is not to scale, but represented in a slightly enlarged manner. The space 56 arranged inside the lower valve sleeve 50, which adjoins the borehole 54, is permanently connected to external air via a transverse borehole 106 in the upper valve sleeve 52 and an obliquely arranged borehole 108 in the housing 34. A further, continuous connection between the space 56 and external air exists via an annular gap 58 between the valve pin 40 and the lower valve sleeve 50.

(18) In the position of the first control valve 22 shown, the lower O-ring 60 is not sealed on the valve pin 40, so that the obliquely arranged borehole 64 and a space 66 connected to it above a locking sleeve 68, which surrounds the second control valve 24, are also deaerated via the transverse borehole 62 in the upper valve sleeve 52.

(19) The locking sleeve 68 is in the indicated initial state in an upper end position in which it is held by the force of a spring 70. This upper end position is an open position. A further force on the locking sleeve 68 is exerted by the pressure in a control volume 72, which surrounds the second control valve 24 in a ring shape. In the indicated initial state, this force is zero because the control volume 72 has not yet been supplied with compressed air and is connected to external air via the borehole 54. In the example represented, the control volume 72 has a volume in the range between 1 ml and 1.5 ml.

(20) As long as the valve pin 48 of the second control valve 24 is in its unactuated position, the lower O-ring 74 is not sealed on the valve pin 48. The upper O-ring 76 is also not sealed on the valve sleeve 78 of the second control valve 24. Therefore, the main control line 20 is connected to external air via a transverse borehole 80 in the locking sleeve 68, running past the upper O-ring 76, via a transverse borehole 82, an annular gap 84 between valve pin 48 and valve sleeve 78 and running past the O-ring 74.

(21) If, starting from the state shown in FIG. 2, the contact sensor 28 is actuated, the valve pin 48 of the second control valve 24 moves against the force of a spring 86 into its actuated position shown in FIG. 3, in which the O-ring 74 is sealed. As a result, the main control line 20 is shut off from external air. In addition, by moving the valve pin 48, its upper O-ring 88 releases the seal, whereby a connection is established between the space 66 and the main control line 20, namely running past the O-ring 88, through the transverse borehole 82, running past the O-ring 76 and through the transverse borehole 80. As the space 66 is still depressurised, no drive-in process is triggered yet.

(22) If, in the next step, the trigger 26 is also actuated, as shown in FIG. 4, the valve pin 40 of the first control valve 22 is moved into its actuated position and the lower O-ring 60 creates a seal and an upper O-ring 90 of the valve pin 40 releases the seal. As a result, there is a connection between the always aerated housing interior 32 and the space 66 via the transverse borehole 62 in the upper valve sleeve 52. This causes immediate aeration of the main control line 20 via the connection described above, so that a drive-in process is triggered. In addition, the control volume 72 is aerated via a non-return valve formed by a middle O-ring 92 on the valve sleeve 78. Immediately afterwards, the control volume 72 is therefore also under operating pressure, just like the space 66. The three forces acting on the locking sleeve 68 continue to act together such that the locking sleeve 68 remains in its upper end position.

(23) If the compressed air nail gun is then removed from the workpiece, the contact sensor 28 moves back downwards so that the valve pin 48 of the second control valve 24 also returns to its initial position, as shown in FIG. 5. As a result, the upper O-ring 88 of the valve pin 48 is sealed again so that no further compressed air supply to the main control line 20 or into the control volume 72 is possible. The pressure in the control volume 72 slowly decreases via the borehole 54. The main control line 20 is deaerated with external air via the connection already described in FIG. 2.

(24) By re-actuating the contact sensor 28, starting from the state of FIG. 5, contact triggering can be carried out at any time because the main control line 20 can be aerated again by moving the valve pin 48 upwards. At the same time, the pressure in the control volume 72 is then refreshed via the non-return valve so that the delay time, within which further contact triggering is possible, starts running again.

(25) However, if the contact sensor 28 remains unactuated for a certain time when the trigger 26 is actuated, the pressure in the control volume 72 falls below a specified pressure threshold. As a result, the balance of the three forces acting on the locking sleeve 68 changes and the locking sleeve 68 enters into its lower end position shown in FIG. 6. The lower end position is a locked position. In this position of the locking sleeve 68, a lower inner circumference of the locking sleeve 68 seals against the O-ring 94 so that a compressed air supply to the control volume 72 via the non-return valve is no longer possible. In addition, the upper O-ring 76 on the valve sleeve 78 creates a seal, so that a compressed air supply is also no longer possible via the transverse borehole 80 to the main control line 20.

(26) Furthermore, the space designated by 96 in FIG. 6 is connected to external air via a non-visible borehole. Since a middle O-ring 98 is not sealed on the locking sleeve 68, the main control line 20 is deaerated via the space 96. Moving the locking sleeve 68 into its locked position therefore represents a safety measure which reliably prevents the triggering of a further drive-in process. Further drive-in processes can only be triggered when the trigger 26 is released and thus the space 66 is deaerated so that the locking sleeve 68 moves back into its open position.

(27) A second exemplary embodiment is explained with reference to FIGS. 7 to 10. With regard to the elements schematically represented in FIG. 1 and with regard to the design of the second control valve 24 with locking sleeve 68, there are no differences in relation to the first exemplary embodiment of FIGS. 1 to 6. The elements adopted unchanged may be provided with the same reference numerals as in the first exemplary embodiment and will not explained again.

(28) There is a difference with the contact sensor lever 42, whose rear end is not fixed to the housing, but is hinged to a rear end of the trigger 26. As a result, the valve pin 48 of the second control valve 24 is not actuated with each actuation of the contact sensor 28, but only when trigger 26 and contact sensor 28 are actuated together. In addition, the space 66 above the locking sleeve 68 is not aerated via the first control valve 22, but is continuously connected to the housing interior 32 via a borehole 100.

(29) The aforementioned changes with respect to the first exemplary embodiment allow a particularly simple configuration of the first control valve 22. This control valve comprises a lower valve sleeve 50 in which the borehole 54 is arranged, as explained in more detail in the first exemplary embodiment. In contrast to the first exemplary embodiment, the first control valve 22 exclusively fulfils the object of optionally aerating or deaerating the control volume 72 via the borehole 54. For this purpose, the first control valve 22, in its unactuated position indicated in FIG. 7 running past the upper O-ring 102, establishes a connection between the space 56 of the inside of the lower valve sleeve 50 and the housing interior 32, while the lower O-ring 60 is sealed. The control volume 72 is thus slowly aerated through the borehole 54. After a certain time has expired, after which the compressed air nail gun has been connected to a compressed air source and during which neither trigger 26 nor contact sensor 28 have been actuated, the compressed air nail gun is located in the initial state shown in FIG. 7. The control volume 72 is under operating pressure and the locking sleeve 68 is in its open position.

(30) FIG. 8 shows the situation after the trigger 26 has been actuated. The upper O-ring 102 of the valve pin 40 is sealed and the control volume 72 is slowly deaerated via the borehole 54. Thus, the delay time starts to run when the trigger 26 is actuated.

(31) If the contact sensor 28 is actuated before expiry of the delay time with the trigger 26 still actuated, the valve pin 48 of the second control valve 24 is moved upwards, as represented in FIG. 9. This triggers a drive-in process in the same way as explained in the first exemplary embodiment. As explained in the first exemplary embodiment, the pressure in the control volume 72 is refreshed via the non-return valve formed by the middle O-ring 92.

(32) After lifting the compressed air nail gun from a workpiece, the valve pin 48 of the second control valve 24 returns to its unactuated position and the control volume 72 is slowly deaerated via the borehole 54. Provided the pressure threshold in the control volume 72 is not undercut, the locking sleeve 68 remains in its open position so that the situation corresponds to that of FIG. 8. Further contact triggering is possible.

(33) However, if the trigger 26 remains actuated without further triggering occurring within the delay time, the locking sleeve 68 is moved into its locked position shown in FIG. 10, which prevents further triggering in the same way as explained in the first exemplary embodiment. In order to enable further triggering, the trigger 26 must first be released again and it is necessary to wait until the pressure in the control volume 72 exceeds the pressure threshold and the locking sleeve 68 is moved back into its open position. Then, the device is again located in the state where it is ready to be triggered, shown in FIG. 8.

(34) In both exemplary embodiments, the housing 30 has two recesses which receive the first control valve 22 and the second control valve 24. The control volume 72 is located within the recess, which receives the second control valve 24.

LIST OF REFERENCE NUMERALS

(35) 10 Working piston 12 Driving ram 14 Working cylinder 16 Main valve 18 Pilot Valve 20 Main control line 22 First control valve 24 Second control valve 26 Trigger 38 Contact sensor 30 Housing 32 Housing interior 34 Handle section 36 Axis 38 Actuating surface 40 Valve pin of the first control valve 42 Trigger lever 44 Axis 46 Actuating surface 48 Valve pin of the second control valve 50 Lower valve sleeve 52 Upper valve sleeve 54 Borehole 56 Space inside the lower valve sleeve 58 Annular gap 60 Lower O-ring 62 Transverse borehole 64 Borehole 66 Space 68 Locking sleeve 70 Spring 72 Control volume 74 Lower O-ring 76 Upper O-ring 78 Valve sleeve 80 Transverse borehole 82 Transverse borehole 84 Annular gap 86 Spring 88 Upper O-ring 90 Upper O-ring 92 Middle O-ring (non-return valve) 94 O-ring 96 Space 98 Middle O-ring 100 Borehole 102 Upper O-ring 104 Lower end 106 Transverse borehole 108 Borehole