EP1117508B1 - Pneumatic percussion power tool with pneumatic returning spring - Google Patents

Description

The invention relates to an air spring hammer mechanism, in which a drive piston and a percussion piston are axially movable in a percussion mechanism housing.

Such striking mechanisms are usually used in rotary or impact hammers used, whereby two types of striking have proven themselves in practice to have. One type relates to a striking mechanism with a hollow, in the drive mechanism guided drive piston, in its cavity the percussion piston is guided while the other type has a percussion mechanism hollow percussion piston guided in the striking mechanism housing concerns, in the cavity of the drive piston is guided. Both types of drums common is that the drive piston z. B. via a crank mechanism is oscillating and is located between the drive piston and the percussion piston forms an air spring that drives the drive transmits the drive piston to the percussion piston and this into a Drive direction where it finally hits a tool, e.g. on one Chisel strikes and transfers its impact energy. Then the bounces Percussion piston back and it starts, supported by the drive piston, a new stroke movement.

Such a striking mechanism is e.g. in US-A-5,108,400.

The advantages of the types of drums described are low demands with regard to the sealing of the joints, so that a use of robust Steel-steel sliding pairings without the use of additional ones Sealing elements in the high pressure area is possible. In addition point the striking mechanisms have good starting behavior at low temperatures.

Nevertheless, there is the problem under certain operating conditions that the Return movement of the percussion piston after the impact despite the recoil pulse and a suction effect of the drive piston is not sufficient, in order to be able to perform a powerful blow afterwards.

The invention has for its object to provide an air spring hammer mechanism, in which the recoil behavior of the percussion piston is improved.

According to the invention, the object is achieved by an air spring hammer mechanism, with a striking mechanism housing; one axially in the striking mechanism housing and drivable drive piston; one, seen in one direction, arranged in front of a drive surface of the drive piston, coaxial to the Drive piston axially movable percussion piston; one in front of the drive surface of the drive piston and arranged behind a rear surface of the percussion piston first chamber; one behind the drive surface of the drive piston trained second chamber; and with one in front of the back surface of the Percussion piston trained third chamber; the second chamber and the third chamber via a connecting channel in communicating connection are feasible.

The design of the air spring hammer mechanism enables the drive piston with a forward movement over a developing in the first chamber Air spring applies its energy to the percussion piston and thus indirectly the tool can pass on. When the drive piston moves back builds up in the second chamber behind the drive piston an air pressure on the connecting channel to that in front of the percussion piston located third chamber is performed. This will, when moving back of the drive piston, the return movement of the percussion piston independently of its rebound after the blow and that of the first chamber transferred suction effect of the drive piston supported. A reliable one Return movement of the percussion piston even under difficult operating conditions is the result, so that when the Drive piston another powerful blow can be performed.

The communicating connection between the second chamber and the third chamber allows one by the movement of the drive piston caused pressure change in the second chamber over the Connection channel affects a pressure change in the third chamber.

In a first preferred embodiment of the invention, the drive piston guided in the striking mechanism housing while the percussion piston guided in a cavity formed on an end face of the drive piston is (claim 2).

Alternatively, this is also in a very advantageous embodiment the percussion piston is guided in the percussion mechanism housing, while the drive piston is guided in a cavity formed in an end face (claim 3).

The solution according to the invention is suitable for both of the air spring hammer types mentioned.

In a preferred further development of the invention, the second chamber between a rear surface of the drive piston and one on the striking mechanism housing attached rear tube sheet arranged while the third Chamber between a front surface of the percussion piston and an am Impact mechanism housing attached front tube sheet is arranged. this makes possible it that the additional chambers compared to the prior art behind the drive piston and in front of the percussion piston without complex additional construction measures can be implemented.

The drive piston is advantageously designed such that it has a the drive surface and the rear surface forming piston head, a holder for attachment to a drive and a the piston head with the bracket connecting connecting link. This design enables that between arranged the piston head and the bracket of the rear tube sheet can be, which forms the second chamber in a simple manner.

In a further advantageous embodiment of the invention is an idle channel provided the at least one in a wall of the drive piston has existing idle opening and a wall of the Percussion mechanism housing penetrates. The idle channel is either with the Connection channel or the environment associated. On the Idle channel, it is possible to short-circuit the first and the second chamber. so that no pressure ratios build up in the air spring hammer mechanism can act on the percussion piston when the air spring hammer mechanism is in idle mode.

In a particularly advantageous embodiment, one is movable Control spool provided between a striking position and a Idle position is switchable and the connection in a striking position between the second and the third chamber via the connecting channel establishes while blocking the idle channel. In an idle position it interrupts the connection channel and opens the idle channel, thereby adjust the transition between idle and striking position precisely to be able to. The axial displacement of the control slide takes place advantageously in that the control slide with the tool or coupled between striking piston and die arranged die, with the tool or the striking die when changing to idle lifting off the rock slides out of the housing a little, causing the spool can also follow the movement.

Fig. 1

eine schematische Schnittdarstellung eines erfindungsgemäßen Luftfederschlagwerks in Schlagstellung;

Fig. 2

das Schlagwerk aus Fig. 1 in Leerlaufstellung;

Fig. 3

eine schematische Schnittdarstellung einer zweiten Ausführungsform des erfindungsgemäßen Luftfederschlagwerks in Schlagstellung;

Fig. 4

das Schlagwerk gemäß Fig. 3 in Leerlaufstellung;

Fig. 5

eine dritte Ausführungsform eines erfindungsgemäßen Luftfederschlagwerks in Schlagstellung;

Fig. 6

das Schlagwerk gemäß Fig. 5 in Leerlaufstellung;

Fig. 7

eine vierte Ausführungsform eines erfindungsgemäßen Luftfederschlagwerks in Schlagstellung;

Fig. 8

das Schlagwerk gemäß Fig. 7 in Leerlaufstellung;

Fig. 9

einen anderen Schlagwerkstyp als fünfte Ausführungsform für ein erfindungsgemäßes Luftfederschlagwerk in Schlag- und Leerlaufstellung.

These and other advantages and features of the invention are explained in more detail below with the aid of the accompanying figures. Show it:

Fig. 1

is a schematic sectional view of an air spring hammer mechanism according to the invention in the striking position;

Fig. 2

1 in the idle position;

Fig. 3

is a schematic sectional view of a second embodiment of the air spring hammer mechanism according to the invention in the striking position;

Fig. 4

3 in the idle position;

Fig. 5

a third embodiment of an air spring hammer mechanism in the striking position;

Fig. 6

5 in the idle position;

Fig. 7

a fourth embodiment of an air spring hammer mechanism in the striking position;

Fig. 8

7 in the idle position;

Fig. 9

another type of striking mechanism as a fifth embodiment for an air spring hammer mechanism according to the invention in striking and idle position.

1 and 2 show an air spring hammer mechanism according to the invention in Beat or idle position.

In a striking mechanism housing 1, a drive piston 2 is turned into a Connecting rod 3 in, not shown, belonging to a known crank mechanism oscillating axial movement offset.

The connecting rod 3 is articulated on a holder 4 of the drive piston 2. The Bracket 4 is integrally connected to a piston head 6 via a central link 5. The thus from the bracket 4, the middle member 5 and the piston head 6 existing drive piston 2 can - differently than shown in the figure - can also be assembled from several parts if this is from manufacturing or installation reasons is appropriate.

A cavity 8 is formed on a front end face 7 of the drive piston 2, in which a percussion piston 9 is inserted axially movable. Between the drive piston 2 and the percussion piston 9 is one of the drive piston 2 surrounded first chamber 10 is provided, in which in the initial state Air with ambient atmosphere.

At the beginning of the striking operation, the drive piston 2 moves forward. i.e. - based on Figures 1 and 2 - to the left. Because of its inertia delayed subsequent percussion piston 9 increases in the first chamber 10 of the air pressure, so that an air spring forms, the transfers its energy to the percussion piston 9 with a delay. This will finally also accelerated forward and only met schematically shown striker 11, where the kinetic energy of the percussion piston 9 is transmitted as impact energy. The striker 11 gives the impact energy to a tool, not shown, e.g. a chisel, on. Instead of of the striker 11, a shank of the tool can also be used directly his.

At the time of the stroke shown in FIG. 1, one in the wall of the drive piston 2 existing air equalization channel 12 opened, whereby the first chamber 10 is ventilated and air losses in a known manner Way can be balanced.

After the blow, the percussion piston 9 bounces back in the direction of the drive piston 2, which due to the crank mechanism is already moving backwards located. By a negative pressure developing in the first chamber 10 the backward movement of the percussion piston 9 is supported until the drive piston 2 again moves forward and a new one Stroke cycle begins.

In the case of percussion mechanisms known from the prior art, it has been found that that under certain operating conditions the return movement of the Percussion piston is unsatisfactory and due to the suction effect in the first chamber is not sufficiently supported. This leads to the percussion piston is not moved back enough and the following one Cannot strike with the required energy. An unsatisfactory one Work result and an irregular one for the operator Behavior of the hammer are the result.

The problem is solved according to the invention in that a connecting channel 13 is provided, the second chamber 14 with a third chamber 15 brings in communicating connection.

The second chamber 14 is - seen in the direction of impact - behind a drive surface 16 of the drive piston 2 arranged. As from Figures 1 and 2 can be seen, the second chamber 14 is one of the piston head 6th provided rear surface 17, one belonging to the striking mechanism housing 1 rear tube sheet 18, the middle member 5 and the actual hammer mechanism housing 1 formed.

The third chamber 15 is arranged in front of a rear surface 19 of the percussion piston 9 and is from a front surface serving as a face 20 of the Percussion piston 9, a front belonging to the percussion mechanism housing 1 Tube plate 21, the actual percussion mechanism housing 1 and the drive piston 2 formed.

Sealing the various joints between the movable ones Sharing is usually not necessary. Steel-steel sliding pairings are usually used here used.

If, after performing a blow, the drive piston 2 moves backwards will not only be moved - as already from the state of the Technology known - a vacuum for sucking back in the first chamber 10 of the percussion piston 9 generated. A is formed in the second chamber 14 Overpressure, which led to the third chamber 15 via the connecting channel 13 and acts there on the striking surface 20 of the striking piston 9. A Support for the backward movement of the percussion piston 9 is the result. Conversely, the forward movement also occurs when the drive piston 2 moves forward of the percussion piston 9 reinforced since one in the second chamber 14 resulting negative pressure also led to the third chamber 15 becomes.

The function of the between the drive surface 16 of the drive piston 2 and the rear surface 19 of the percussion piston 9 is formed first chamber 10 not affected by this.

In a wall 22 of the drive piston 2 there are several idle openings 23 formed in front of one formed in the striking mechanism housing 1 Move the idle groove 24 back and forth when the drive piston 2 moves axially. The idle groove 24 is connected to the connecting duct via an air duct 25 13 in connection. The idle openings 23, the idle groove 24 and the air duct 25 together form an idle duct.

The striking mechanism goes idle when the operator of a drilling or Hammer, in which the striking mechanism is used, the tool from the rock to be processed. This causes the tool to slide and the striker 11 a certain distance from the striking mechanism housing 1 out. The percussion piston 9 follows this path and reaches the one in FIG. 2 position shown. The percussion piston 9 passes over an area of one Fixed edge 26, which creates a connection between the first Chamber 10 via the idle openings 23, the idle groove 24 and the air duct 25 to the connecting channel 13 is formed.

By establishing the connection between the first chamber 10 and the second chamber 14 and the third chamber 15 is the air system shorted. This means that the further movement of the drive piston 2 not only the air from the second chamber 14 - as in Blow operation - in the third chamber 15, but also in the first chamber 10 is pumped where they are largely the same for air balancing Air pressure in all three chambers ensures. The percussion piston 9 is thereby not displaced from its foremost position.

For completion, reference is made to a ventilation opening 27 with a possibly building air cushion between the rear Dismantle tube sheet 18 and the bracket 4.

3 and 4 schematically show a sectional view of a second Embodiment of the invention. The same parts as in the first embodiment are identified with the same reference numerals, whereby a new description is dispensed with.

Compared to the first embodiment shown in FIGS Invention is an axially displaceable in the second embodiment Control slide 28 is provided by a against the striking mechanism housing 1 supported spring 29 is acted upon on one side. The control slide 28 can be depending on the position of the striker 11 between one in Fig. 3 shown impact position and an idle position shown in Fig. 4 move.

In the control slide 28 is a connection opening 30 and an idle opening 31 provided. The control slide 28 is in the striking position in a position in which the connection opening 30 a connection between the connecting channel 13 and the third chamber 15 allows while the control slide 28 connects the first chamber 10 to the environment prevents that the idle opening 31 is not above the Air duct 25 is.

When changing between striking and idling operation, the striker 11 slide, the percussion piston 9 and the control slide 28 a certain distance in Towards the tool, whereby the connection opening 30 connects the connection channel 13 interrupts while the idle opening 31 via the air duct 25 is moved. This allows the first chamber 10 to communicate with the environment be associated, resulting in reliable idle behavior established.

The use of the control slide 28 requires a larger structural Effort, but has the advantage that the idle travel, i.e. the Path by which the tool must slide out of the striking mechanism housing 1 is shortened can become what is reflected in a shorter design.

As can be seen in Fig. 4, builds up when the drive piston moves back 2 in the second chamber 14 to an air pressure which is via the connecting channel 13 cannot be removed. To avoid extreme Pressing is therefore a double-acting pressure relief valve 13a in the connecting channel 13 provided.

A variant of this is shown as a third embodiment in FIGS. 5 and 6 again in the striking and idling position. This third embodiment differs from the second embodiment according to FIGS. 3 and 4 in that the control slide 28 has a greater axial length and still extends over the region of the second chamber 14.
In addition to the connection opening 30 and the idle opening 31, a connection opening 32 and a ventilation opening 33 are provided in the control slide 28.

As can be seen in FIGS. 5 and 6, the control slide 28 is in the Location, all openings to the first chamber 10, the second chamber 14 and the third chamber 15 to control. When the spool 28 in 5 is in the striking position, he puts over the connecting channel 13 a communicating with the connection openings 30 and 32 Connection between the second chamber 14 and the third chamber 15 ago.

In the idle position, the control slide 28 is guided forward, whereby the idle opening 31 is moved via the air duct 25 and a connection between the first chamber 10 and the environment To avoid pressure build-up in the first chamber 10. Will continue A connection between the second chamber via the ventilation opening 33 14 and the environment, so that the second chamber 14 vent can, without air must be discharged through the connecting channel 13 or that an increased air pressure arises in the connecting duct 13.

As an alternative to this, another fourth shown in FIGS. 7 and 8 will be used Embodiment proposed, which is different from that shown in FIGS. 3 to 6 Embodiments differs in that the connecting channel 13 via a connecting piece 34 to the idle opening 31 in the control slide 28 is performed.

This enables the first and the second - similar to FIGS. 1 and 2 Short circuit chamber 10, 14 so that when the drive piston pumps 2 no pressure increase in the first or second chamber 10, 14 takes place.

The third chamber 15 is through the spool 28 from the connecting channel 13 separated and thus does not experience any increase in pressure either. The Percussion piston 9 remains in the position shown in Fig. 8 without the Drive piston 2 can be lifted off.

Only when the operator puts the tool back on the rock and so that the striker 11 moves to the rear, also the percussion piston 9 and the control slide 28 moved rearward, whereby the Field operation is resumed.

9 shows, as a fifth embodiment, another type of the invention Air spring hammer mechanism, in which a percussion piston 40 in a hammer mechanism housing 1 is guided axially movable. In the top half of Fig. 9 is the striking mechanism is shown in striking position, while the lower half of Fig. 9 shows the striking mechanism in the idle position.

A cavity 42 is located on a rear end face 41 of the percussion piston 40 formed in which a drive piston 43 is guided.

The drive piston 43 is similar to the previous embodiments constructed and consists essentially of a bracket 44, a central link 45 and a piston head 46.

Between a drive surface 47 of the drive piston 43 and a rear surface 48 of the percussion piston 40, a first chamber 49 is formed.

A second embodiment is analogous to the embodiments already described Chamber 50 behind a rear surface 51 of the drive piston 43 and one third chamber 52 formed in front of a front surface 53 of the percussion piston 40. The second chamber 50 and the third chamber 52 are through a communication channel 54 connected.

The percussion piston 40 has an extension 55, one of which is not shown Döpper or a tool, also not shown, applied.

From the connecting channel 54 there is an idle channel 56 which is in the idle position of the striking mechanism a connection between the first chamber 49 and the second chamber 50. A junction 57 of the connecting channel 54 is covered in this case by the percussion piston 40, so that communication between the second chamber 50 and the third Chamber 52 is interrupted.

The further structure of the striking mechanism corresponds to that already described Embodiments, so that a new description is dispensed with can be. Of course, the different design options with regard to the connecting channel and the spool can also be transferred to this type of impact.

The second chamber can be used in other embodiments of the invention also a small-sized one, in connection with the connecting channel space that can be brought in and sealed off from the environment, the one behind the drive piston is arranged and in which at least part of the drive device is provided for the drive piston.

Claims (13)

1. Pneumatically cushioned striking mechanism, having

   a striking mechanism housing (1);

   a drive piston (2; 43) which can be driven axially in a reciprocating manner in the striking mechanism housing (1);

   a striking piston (9; 40) which is disposed in the striking direction in front of a drive surface (16; 47) of the drive piston (2;43) and can move axially coaxial to the drive piston;

   a first chamber (10; 49) disposed in front of the drive surface (16; 47) of the drive piston (2;43) and behind a rear surface (19; 48) of the striking piston (9; 40);

   a second chamber (14; 50) formed behind the drive surface (16; 47) of the drive piston (2; 43); and having

   a third chamber (15;52) formed in front of the rear surface (19; 48) of the striking piston (9; 40);

   wherein the second chamber (14; 50) and the third chamber (15; 52) can be brought into communicating connection by means of a connection channel (13; 54).
2. Pneumatically cushioned striking mechanism as claimed in claim 1, characterised in that

   the drive piston (2) is guided in the striking mechanism housing (1);

   the drive surface (16) of the drive piston (2) is formed in a cavity (8) in a front end surface (7) of the drive piston;

   the striking piston (9) is guided in the cavity (8) of the drive piston (2); and that

   the first chamber (10) is provided in the cavity (8) of the drive piston (2).
3. Pneumatically cushioned striking mechanism as claimed in claim 1, characterised in that

   the striking piston (40) is guided in the striking mechanism housing (1);

   the rear surface (48) of the striking piston (40) is formed in a cavity (42) in a rear end surface (41) of the striking piston;

   the drive piston (43) is guided in the cavity (42) of the striking piston (40); and that

   the first chamber (49) is provided in the cavity (42) of the striking piston (40).
4. Pneumatically cushioned striking mechanism as claimed in one of the preceding claims, characterised in that the second chamber (14) is disposed between a rear surface (17) of the drive piston (2) and a rear tube base (18) attached to the striking mechanism housing (1).
5. Pneumatically cushioned striking mechanism as claimed in one of the preceding claims, characterised in that the third chamber (15) is disposed between a front surface (20) of the striking piston (9) and a front tube base (21) attached to the striking mechanism housing (1).
6. Pneumatically cushioned striking mechanism as claimed in one of the preceding claims, characterised in that the drive piston (2) has a piston head (6) forming the drive surface (16) and the rear surface (17), a holding device (4) for attachment to a drive, and an intermediate member (5) connecting the piston head (6) to the holding device (4).
7. Pneumatically cushioned striking mechanism as claimed in claim 6, characterised in that the rear tube base (18) is disposed between the piston head (6) and the holding device (4) of the drive piston (2) and has the intermediate member (5) of the drive piston (2) passing through it.
8. Pneumatically cushioned striking mechanism as claimed in one of the preceding claims, characterised in that an idling channel (23, 24, 25) is provided which has at least one idling orifice (23) provided in a wall (22) of the drive piston (2) and passes through a wall of the striking mechanism housing (1).
9. Pneumatically cushioned striking mechanism as claimed in claim 8, characterised in that in idling operation the first chamber (10) can be connected to the connection channel (13) by means of the idling channel (23, 24, 25).
10. Pneumatically cushioned striking mechanism as claimed in claim 9, characterised in that an axially displaceable control slide (28) is provided which, in a striking setting, opens the connection channel (13) and blocks the idling channel (23, 24, 25) and, in an idling setting, blocks the connection channel (13) and opens the idling channel, wherein the first (10) and the second (14) chambers can be brought into communicating connection.
11. Pneumatically cushioned striking mechanism as claimed in claim 8, characterised in that in idling operation the first chamber (10) can be connected to the environment by means of the idling channel (23, 24, 25).
12. Pneumatically cushioned striking mechanism as claimed in claim 11, characterised in that an axially displaceable control slide (28) is provided which, in a striking setting, opens the connection channel (13) and blocks the idling channel (23, 24, 25) and, in an idling setting, blocks the connection channel (13) and opens the idling channel (23, 24, 25).
13. Pneumatically cushioned striking mechanism as claimed in claim 1, characterised in that the second chamber is disposed behind the drive piston (2, 43).

Images