EP0727285A1 - Fastening tool with a piston driven by compressed gas - Google Patents

Abstract

The nail gun comprises a piston (6) propelled by compressed gas inside a cylinder (3). It also has a nail guide (5), a sleeve (4) for a combustion chamber (10), and a head (2) equipped with an igniter. A gas reservoir feeds an injector (17), whilst a feeler opens and closes the chamber. The cylinder is able to move inside the housing of the gun. The nail guide ensures the operation of the feeler and moves together with the cylinder, which also contains piston retaining elements (32). During operation a charge of gas is let into the combustion chamber, where it is mixed with air by a fan and then ignited, causing the piston to travel forwards and driven in the nail (15).

Description

The present invention relates to a buffer sealing apparatus by a piston propelled by compressed gas, comprising a buffer guide, a cylinder in which the piston is mounted, a combustion chamber sleeve mounted slidingly for, during support of the device, close the chamber, at the rear, with a cylinder head carrying ignition means and, at the front, with the piston and the cylinder, a gas reserve, gas injection means in the chamber and a feeler for resting and closing the chamber.

Such an apparatus is taught in particular by US-A-4 403 722.

Apparatuses of this type, intended for fixing, for example, wood or strips on steel or concrete, offer the advantage of great autonomy, thanks to the capacity of the gas reserve cartridges with which they are equipped. With a single cartridge, you can fire about a thousand shots. However, these devices have the drawback of a relatively limited power, in particular because of the too low calorific power of the gas.

The Applicant therefore wanted to increase the power of the devices of the type mentioned above by proposing an appropriate solution to the problem of compression of the gas after closing the combustion chamber, and this, perfectly independently of the teaching of US-A-4 712,379 which has nothing to do with that of US-A-4,403,722.

The apparatus of the present invention is characterized in that the cylinder is mounted movable in translation in a housing of the apparatus, the buffer guide performs a probe function and it is integral in translation with the cylinder and there are provided means for retaining the piston in the cylinder.

Thanks to the mobility of the cylinder in the housing of the appliance, the Applicant has therefore transformed the appliance of US-A-4 403 722 into a more powerful appliance, the volume of the combustion chamber of which, after it has been closed, can be reduced.

The cylinder can be secured to an anterior skirt slidingly mounted on the rear housing.

But in the preferred embodiment of the apparatus of the invention, the housing extends axially along the entire sleeve and the entire cylinder.

Advantageously, means are provided which are arranged to drive the sleeve backwards under the action of the translational displacement of the bearing of the cylinder.

Advantageously, the action of the means for driving the sleeve towards the rear is exerted against the action of means for returning the cylinder towards the front of the housing of the device.

Advantageously also, the means for driving the sleeve towards the rear comprise at least one lever pivotally mounted on the cylinder against the action of a spring secured, by its ends, to the lever and to the housing of the device.

Still advantageously, the cylinder is slidably mounted in the sleeve which has a groove open towards the front, in which extends a lug secured to the cylinder, intended to come into abutment against the rear bottom of the groove only after closing of bedroom.

Preferably, the cylinder is slidably mounted in the sleeve towards the front under the action of the return means to open the chamber at the front before it opens at the rear by disengaging the sleeve from the cylinder head. .

Thanks to this, a fan, put in the sleeve by abutment of the sleeve against the cylinder head, when the device is supported, and therefore always running at the front opening of the chamber, can suck in it. 'fresh air.

To constitute the means of retention of the piston in the cylinder, the internal bore of the cylinder for receiving the piston can be widened towards the rear and form a ramp and the piston comprise a peripheral annular groove of retention in which is disposed a retention segment. arranged for cooperate with the ramp and retain the piston when the cylinder recedes after closing the chamber.

Preferably, the piston comprises, in front of the retaining groove, an annular peripheral sealing groove in which is disposed a sealing segment arranged to cooperate with the wall of the internal bore of the cylinder.

The apparatus of US-A-4 403 722, the cylinder of which has been made mobile in the housing, therefore comprises a combustion chamber with a volume which can be reduced to make the apparatus more powerful.

From the same apparatus of US-A-4 403 722, the same problem of the increase in power can be solved in a slightly different way from that claimed previously.

The apparatus of the type mentioned above can therefore also, in the context of the present invention, be improved and have a combustion chamber with reducible volume thanks to the fact that, the probe being integral in translation with the sleeve, the cylinder is mounted movable in translation in a housing of the device, the feeler function during resting is ensured successively by the feeler secured to the sleeve then by the buffer guide and means are provided for retaining the piston in the cylinder .

Preferably, in this case, the feeler secured to the sleeve includes means arranged so as not to hinder the feeler function of the buffer guide.

• la figure 1 est une vue en coupe axiale d'une première forme de réalisation de l'appareil, chambre de combustion ouverte ;
• la figure 2 est une vue analogue à la figure 1, chambre de combustion fermée ;
• la figure 3 est une vue analogue à la figure 2, en fin de mise en appui, chambre de combustion toujours fermée et à volume réduit ;
• la figure 4 est une vue latérale de l'ensemble cylindre-manchon de l'appareil des figures 1 à 3, partiellement en coupe ;
• la figure 5 est une vue à plus grande échelle, en coupe, du mécanisme d'entraînement vers l'avant du manchon par le cylindre de l'appareil des figures 1 à 4;
• la figure 6 est une vue à plus grande échelle, en coupe, du mécanisme d'arrêt du recul du cylindre de l'appareil des figures 1 à 5;
• la figure 7 est une vue à plus grande échelle, en coupe, de la portion arrière du cylindre, en position de fermeture de la chambre de combustion de l'appareil des figures 1 à 6;
• les figures 8A, 8B, 8C illustrent schématiquement le fonctionnement d'une deuxième forme de réalisation de l'appareil de l'invention.

The invention will be better understood using the description of the preferred embodiment of the apparatus of the invention, with reference to the accompanying drawing, in which

• Figure 1 is an axial sectional view of a first embodiment of the apparatus, open combustion chamber;
• Figure 2 is a view similar to Figure 1, closed combustion chamber;
• Figure 3 is a view similar to Figure 2, at the end of support, combustion chamber still closed and reduced volume;
• Figure 4 is a side view of the cylinder-sleeve assembly of the apparatus of Figures 1 to 3, partially in section;
• Figure 5 is an enlarged view, in section, of the drive mechanism towards the front of the sleeve by the cylinder of the apparatus of Figures 1 to 4;
• Figure 6 is an enlarged view, in section, of the recoil stop mechanism of the cylinder of the apparatus of Figures 1 to 5;
• Figure 7 is an enlarged view, in section, of the rear portion of the cylinder, in the closed position of the combustion chamber of the apparatus of Figures 1 to 6;
• Figures 8A, 8B, 8C schematically illustrate the operation of a second embodiment of the apparatus of the invention.

The device shown in the figures will only be described by its only elements which distinguish it from that of US-A-4 403 722 as well as naturally by its elements necessary for understanding the invention.

The apparatus essentially comprises, in a housing 1, a cylinder head 2, a cylinder 3, a sleeve 4, a buffer guide 5, partly projecting from the housing, and a piston 6 for propelling the buffer, all of these elements , of axis 7. The piston 6 is slidably mounted in the cylinder 3 which is slidably mounted in the sleeve 4 which is itself slidably mounted in the housing 1. The relative sliding of the cylinder 3 and of the sleeve 4 is however limited, as we will see later. The buffer guide 5 is screwed onto the cylinder 3.

The sleeve 4 comprises at the rear a neck 8 which can abut against a corresponding zone 9 of the cylinder head, to close, at the rear, a combustion chamber 10. The sleeve 4 also comprises, substantially in part median, an internal annular surface 11 intended to receive a seal 12 carried in an annular groove at the rear of the cylinder 3, to close, at the front, the combustion chamber 10.

A spark plug 13 and a mixing fan 14 are carried by the cylinder head 2.

When a tampon 15 is put in place in the tampon guide 5, the apparatus is pressed against the material 16 intended to receive the tampon 15. The tampon guide 5 then acts as a feeler.

An injection pipe 17 is formed through the cylinder head 2, opening into the combustion chamber 10, for the arrival of the propellant gas from a cartridge and a metering device, not shown.

The cylinder head 2 carries a switch 18 intended to be actuated by the rear part of the sleeve 4, adjacent to its neck 8, when this neck comes into abutment against the zone 9 for closing the chamber of the cylinder head.

A cylinder return cup 19, open towards the rear, is here screwed, by its bottom 20, to the housing 1. It is extended, towards the rear, by two rods 21 diametrically opposite and parallel to the axis 7, at the free end of which is fixed one end of a return spring 22. The other end of the springs 22 is fixed to a lever 23 pivotally mounted on a lug 24 driven substantially radially into the cylinder 3. The end of each lever 23, opposite to that to which a spring 22 is fixed, carries a free support roller 25.

The sleeve 4 has two large lateral notches 26, around the levers 23, with a rear bottom 27, in a transverse plane, against which a roller 25 is in abutment.

The sleeve 4 also comprises, formed from its front edge, a groove 28, parallel to the axis 7, therefore open towards the front and into which is introduced a lug 29 screwed into the cylinder 3 and intended to come into abutment against the bottom of the groove when resting, to limit sliding towards the rear of the cylinder 3 after abutment of the sleeve 4 against the cylinder head 2.

The sleeve 4 also includes a closed lumen 30, parallel to the axis 7, into which is introduced another screw 31 screwed into the cylinder 3 and intended to cooperate with the anterior bottom of the lumen when the apparatus opens, at the support outlet, for driving the sleeve 4 by the cylinder 3.

The rear of the cylinder 3 has an annular recess in which are housed a piston retaining ring 32 and a piston stop ring 33. The first is to temporarily prevent the relative sliding forward of the piston in the cylinder and the second, to prevent the piston from coming out of the cylinder backwards.

The ring 32 has a rear internal portion of enlarged diameter 45 which is connected to the front portion, substantially of the same diameter as the piston head 35, by a frustoconical ramp surface 34. The piston 6 comprises an enlarged rear head 35 in which two peripheral annular grooves 36, 37 are formed, the first, anterior, receiving a sealing segment 38 and, the second, posterior, a retention segment 39. In the resting state, the retention segment 39 projects out from his throat.

After the structural description of the sealing apparatus with an internal combustion engine, its operation will now be presented.

Support

In the rest position, the cylinder 3 is returned by the springs 22 towards the front, against the housing 1, by means of the cup 19 and the buffer guide 5 (FIG. 1).

When the apparatus is pressed against the material 16 intended to receive a tampon 15, the tampon guide 5, as a feeler, drives the cylinder 3 backwards, in the housing 1 and, by intermediate of the levers 23 and notches 26, the sleeve 4 until the latter comes to bear, by its neck 8, against the zone 9 of the cylinder head 2 and closes the rear of the combustion chamber 10 (FIG. 2) . During this recoil, the gas cartridge released a dose of gas into the combustion chamber 10. At the end of recoil of the sleeve 4, by the switch 18, the fan 14 is started to stir the air-gas mixture and the gasket 12 of the cylinder 3 is located just in front of the annular surface 11 of the sleeve, the combustion chamber is closed at the front by the gasket contact 12 of the cylinder 3 - surface 11 of the sleeve 4 and the segment contact d seal 38 of the piston 35 - internal bore 40 of the cylinder 3.

The recoil of the cylinder-sleeve assembly 3,4 from the position of FIG. 1 to that of FIG. 2 was effected against the action of the springs 22 which are progressively tensioned by pivoting the levers 23.

After closing the chamber 10, and continuing to press the device against the material 16, the operator will reduce the volume of the chamber to further compress the propellant gas. The sleeve 4 being immobilized against the cylinder head 2, the buffer guide 5 continues to roll back the cylinder 3 until the lug 29 integral with the cylinder 3 abuts against the rear bottom 41 of the groove 28 of the sleeve 4 (figure 3). During this displacement of the cylinder 3, from the position of FIG. 2 to that of FIG. 3, the seal 12 of the cylinder has slid against the surface 11 of the sleeve to be at the rear of the latter, and to reduce by as much the volume of the chamber 10. The piston 35 remained integral in sliding of the cylinder 3 thanks to the retention of the retention segment 39 by the ramp 34 of the ring 32.

Shoot

The shot takes place when the candle 13 ignites. A spark causes the explosion which creates a pressure greater than the force of the retention segment 39. The latter retracts into its groove 37 by sliding on the ramp 34 and the piston 35 thus escapes from the retention ring 32. During the stroke of the piston 35, the segment 39 behaves like a conventional segment.

The piston rod 6 strikes the buffer 15 which is fixed in the material 16. The piston continues its stroke until its head 35 comes against the damper 42.

When the piston head 35 has passed beyond the exhaust valve 43 of the cylinder 3, the gases escape, the "engine" cools rapidly and a vacuum causes the valve 43 to close and the piston to return 35 back in the firing position, against the stop ring 33; the retaining segment 39 expands to retain the piston 35 behind the ramp 34 of the retaining ring 32.

During this return trip of the piston 6.35, the cylinder-sleeve assembly did not move.

Support outlet

Under the action of the springs 22 which relax, the levers 23 push the sleeve 4 towards the rear which remains in abutment against the cylinder head 2. With respect to the sleeve, the cylinder 3 is returned towards the front under the action of the springs 22. Just after the parts of the appliance have returned to their position in FIG. 2, the combustion chamber 10, closed at the rear, opens at the front and the fan 14 expels the burnt gases through lights made in the sleeve 4.

Immediately after the start of the driving of the sleeve 4 by the cylinder 3, the combustion chamber 10 also opens at the rear, by clearing the neck 8 from the zone 9 of the cylinder head 2, and the fan 14 sucks in fresh air through the lights in the cylinder head.

When the screw 31 comes into abutment against the front bottom of the lumen 30 of the sleeve 4, the latter is driven forward by the cylinder 3 until the latter returns to the rest position against the housing 1, ready for the attachment of a new buffer from the charger 44.

It will be noted that the lug 29 makes it possible to adjust the compression ratio and that if this ratio does not have to be modified, other even simpler means can be provided for limiting the sliding of the cylinder towards the rear.

The relative dimensions of the piston head 35, of the retention ring 32 and of its ramp 34 are adapted to the desired retention force. The ring 32 should be considered as a wearing part; the cylinder 3 and the rings 32, 33 could be one piece.

In the example considered above, in fact two sealing surfaces have been provided, of the type of surface 11, on the sleeve 4, axially offset. Thanks to this, a better compression ratio can be obtained.

In its embodiment of Figures 8A, 8B, 8C, the apparatus of the invention is not fundamentally different from that of Figures 1-7. It is essentially distinguished from it by the fact that it is a little closer to the starting device of document US-A-4 403 722, the probe remaining integral with the sleeve.

The apparatus of these last three figures comprises a buffer guide 50, a cylinder 51, in which is mounted a piston with retention means in the cylinder, a sleeve 52 of combustion chamber 53, a cylinder head 54, a reserve of gas, means for injecting the gas into the chamber and a feeler 55. The feeler 55 is integral in translation with the sleeve 52. The sleeve 52 is slidably mounted in the housing 56, against return means 57. The cylinder 51 is mounted movable in translation relative to the sleeve 52, against return means 58.

When the apparatus is placed in support, the feeler 55 begins by pushing the sleeve 52 backwards to close the chamber 53 with the breech 54 at the rear. When the buffer guide 50 comes into contact with the material -support 61 against which the device is pressed, the buffer guide 50 thus performs a probe function to drive the cylinder 51 and the piston 59 backwards and finish closing the chamber 53 at the front, with the piston 59 and the cylinder 51 (FIG. 8B).

By providing the support, the buffer guide 50 continues to drive the cylinder 51 and the piston 59 backwards in the sleeve 52, to reduce the volume of the chamber 53 (FIG. 8C).

As soon as the buffer guide 50 also begins to perform a probe function, the probe 55 itself must not cause this function. This is why the probe 55 includes means intended for this. In this case, it comprises a compressible intermediate spring 60. But it could also have a telescopic part.

Claims (14)

Tampon sealing apparatus (15) by a piston (6,35) propelled by compressed gas, comprising a tampon guide (5), a cylinder (3), in which the piston (6) is mounted, a sleeve (4 ) of combustion chamber (10) slidably mounted so that, when the appliance is supported, close the chamber (10), at the rear, with a cylinder head (2) carrying ignition means (13 ) and, at the front, with the piston (35) and the cylinder (3), a gas reserve, means (17) for injecting the gas into the chamber and a feeler (5) for resting and chamber closure (10), characterized in that the cylinder (3) is mounted movable in translation in a housing (1) of the device, the buffer guide (5) performs a probe function and is integral in translation of the cylinder (3) and means (32, 37, 39) are provided for retaining the piston (35) in the cylinder (3). Apparatus according to claim 1, in which the cylinder is integral with an anterior skirt slidably mounted on the rear housing. The apparatus of claim 1, wherein the housing (1) extends axially along the entire sleeve (4) and the entire cylinder (3). Apparatus according to one of claims 1 to 3, in which means (23,26) are provided arranged to drive the sleeve (4) rearward under the action of the displacement translation movement of the bearing of the cylinder ( 3). Apparatus according to claim 4, in which the action of the means (23) for driving the sleeve (4) towards the rear is exerted against the action of means (22) for returning the cylinder (3) towards the front of the device housing (1). Apparatus according to claim 5, in which the means for driving the sleeve towards the rear comprise at least one lever (23) pivotally mounted on the cylinder (3) against the action of a spring (22) secured by its ends, lever (23) and housing (1) of the device. Apparatus according to one of claims 3 to 6, in which the cylinder (3) is slidably mounted in the sleeve (4) which has a groove (28) open towards the front, in which extends a lug (29) integral with the cylinder (3), intended to come into abutment against the rear bottom (41) of the groove (28) only after closure of the chamber ( 10). Apparatus according to one of claims 5 to 7, in which the cylinder (3) is slidably mounted in the sleeve (4) forwards under the action of the return means (22) to open the chamber (10) to the front before it opens at the rear by disengaging the sleeve (4) from the cylinder head (2). The apparatus of claim 8, wherein the combustion chamber (10) has a fan (14). Apparatus according to one of claims 1 to 9, in which the means for retaining the piston (35) in the cylinder (3) comprise a retention segment (39) disposed in a peripheral retaining groove (37) for the piston (35 ) and arranged to cooperate with a ramp (34) formed between two anterior (40) and posterior portions of enlarged diameter (45) of the internal bore for receiving the pistons (35) in the cylinder (3). Apparatus according to claim 10, in which the piston (35) comprises, in front of the retaining groove (37), an annular sealing peripheral groove (36) in which is disposed a sealing segment (38) arranged to cooperate with the wall (40) of the internal bore of the cylinder (3). Apparatus according to one of claims 10 and 11, wherein the retention ramp (34) is formed on a retention ring (32). Buffer sealing apparatus by a piston (59) powered by compressed gas, comprising a buffer guide (50), a cylinder (51), in which the piston (59) is mounted, a combustion chamber sleeve (52) (53) mounted so as to slide, when the device is resting, close the chamber (53), at the rear, with a cylinder head (54) carrying ignition means and, at the front, with the piston (59) and the cylinder (51), a gas reserve, means for injecting the gas into the chamber and a feeler (55) for pressing and closing the chamber integral in translation with the sleeve (52 ), characterized in that the cylinder (51) is mounted movable in translation in a housing (56) of the device, means for retaining the piston in the cylinder being provided, and the feeler function, during the abutment, is ensured successively by the feeler (55) integral with the sleeve (52) then by the guide- buffer (50). Apparatus according to claim 13, wherein the feeler (55) integral with the sleeve (52) comprises means (60) arranged so as not to interfere with the feeler function of the tampon guide.

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