EP0849005A1 - Pneumatic knocker - Google Patents

Abstract

The hammer has a housing containing a sliding impact piston (18) with a connecting channel (42) for a pressurised medium leading from a supply connection to a pressure biasing chamber (40). The connecting channel has a straight main section which, starting from the pressure biasing chamber, comprises an axial channel through the piston and an adjoining pipeline (34,64) in or through the spring chamber (28). A branch channel of a valve unit is formed by through openings (46) in the wall of this pipeline. The pipeline comprises a tube (34) connected on one side fixed to the housing end wall (6) on the spring chamber side and on the other side is projected into an axial bore (30) of the piston in which it slides sealed in same.

Description

The invention relates to a pneumatic knocker, also as an impact cylinder referred to, according to the preamble of claim 1.

The terms "pneumatic" and "pressure medium" should be used in the sense of this Registration for the use of any gaseous or vaporous Sourcing energy.

In contrast to pneumatic vibrators, where one is in a cylinder reciprocating pistons often alternately from both sides the pressure medium is applied with a pneumatic knocker of the type discussed here, only the cylinder space on one side of the piston pressurized with pressure to the piston against the restoring force of a to move against the other side of the piston. At Sudden pressure relief of the cylinder chamber, the piston suddenly returned by the spring.

A pneumatic knocker of this type is, for example, in DE-A-25 49 551 described. Basically, it would be possible with knockers of this type To vent the pressurization chamber suddenly into the environment. This However, the approach has several disadvantages. Because of the fast The piston moves back when it strikes in the spring chamber of the Cylinder a negative pressure, the stroke movement of the piston strong would affect. In principle, this disadvantage could be explained by this reduce that the spring chamber in turn through flow openings with the Environment is connected. However, this would mean that with everyone Stroke ambient air is sucked into the spring chamber, depending on Environmental conditions would lead to contamination of the cylinder. In addition, constant flow noise would be noticeable do. It is therefore common practice for knockers of the type concerned here the pressurization chamber of the piston through a quick exhaust valve to vent into the spring chamber, so that practically an overflow the air takes place from one cylinder space to the other. The fact that at the sudden return movement of the piston in the spring chamber a negative pressure arises, the overflow process is accelerated. When renewed In such an embodiment, the piston must be pressurized, in which the spring chamber is essentially closed, but one Ventilation opening of a certain size is provided in the wall of the spring chamber so that the air transferred into the spring chamber when renewed Actuation of the piston with fresh compressed air can escape. Since the Time for the preload of the piston against the restoring force of the spring a knocker is not critical, the vent for the Spring space to be relatively small. On the other hand, it comes to knockers that the vent from Pressurization chamber in the spring chamber takes place as quickly as possible.

In the subject of DE-A 25 49 551 is therefore a hose relatively large cross section provided that Pressurization chamber outside the cylinder via a Quick exhaust valve connects to the spring chamber. Because one or more such hoses out of the cylinder for certain reasons are impractical, were the subject of DE-A 38 19 111 Overflow lines laid in the cylinder wall and in the spring chamber side Cylinder head a specially designed quick exhaust valve is provided. Functionally, this embodiment was an improvement, in terms of production technology, however, it is more expensive and more complicated because one Cylinder wall with a limited thickness can be drilled several overflow channels must then flow again through the valve need to be merged, with a considerable Flow resistance arises.

A pneumatic linear vibrator is known from EP-A 330 687, in which the compressed air is fed through a pipe which passes through the interior of a drilled piston. However, this pipe is only on his Air inlet ends open and closed at the opposite end, and the Air control takes place via narrow grooves and channels in the wall of this pipe and the inner wall of the bore of the piston. An acceleration of the Flow of the working air is due to the specified version previously known linear vibrator not reached.

The invention has for its object a pneumatic knocker, such as it is known in its nature from DE-A 38 19 111, in its Mode of action still to be improved and production technology too simplify, in particular for use in pharmaceutical companies, in the food industry etc. a smooth, easy-to-clean surface is desired.

This task is fundamentally characterized by the characteristics of the Claim 1 solved.

Due to the straight line of the connecting channel directly on the Pressurization chamber through the piston into the spring chamber the shortest overflow path from the pressurization chamber into the Realize spring space. In addition, the axial channel in the piston without be formed with a required cross section. Let also the passage openings forming the branch channel in the wall of the to the piston bushing for a pipeline direct connection with the spring chamber and in a sufficiently large one Form cross-section. From a manufacturing point of view, these measures are relative simple.

The one adjoining the channel in the piston is expedient Line routing at least partially as a pipe or pipe section educated. Because this tube also makes a transition from the piston movement the axial channel in the piston in the subsequent cable routing must ensure there are basically two ways of attachment this pipe. In a first embodiment, the tube extends entirely through the spring chamber and is with one side on the End wall of the housing on the spring chamber side, where it is expedient communicates with the supply port for the printing medium. The the other end of the tube protrudes into an axial bore of the piston, in which it is sliding and sealed. The piston thus moves not only on the inner wall of the cylinder jacket but also on the Along the outside wall of this pipe.

In an alternative embodiment, one is in the spring chamber protruding pipe section directly on the spring side end face attached to the piston. This pipe section thus moves with the Percussion piston back and forth. The connection path for the to be fed Compressed air can also be made in different ways. In a first embodiment is the free end of the pipe section with a pressure-resistant metal bellows, the other end in turn with the Spring chamber-side housing end wall is connected and there with the Supply port for the print medium is in communication. This Bellows take the play of movement carried by the percussion piston Pipe section on. The metal bellows can with certain design even have a supportive spring effect. One more way the compressed air supply consists of the pipe section by another rigid or flexible pipe, for example a pressure-resistant hose extend and in a guide through the spring chamber end wall of the Pass through the housing. The supply port for the print medium is expediently provided at the end of this pipe which is led out. A disadvantage of this embodiment is that there may be - insofar no additional protective cap is provided - a moving part outside of the knocker housing, which is in the event of improper contact Injury. Basically, it is also possible to move to the end of the Pipe section to connect a flexible air supply hose that is guided somewhere through the housing wall of the spring chamber and inside of the spring chamber has enough play to the piston movements to catch.

In all embodiments except the latter, it is conceivable that Quick exhaust valve, for example, in the spring chamber side Arrange the front wall of the housing and the openings in the wall of the Line routing even outside of the cylinder housing to provide there the overflow air, for example, through the spring chamber side End wall in the spring chamber. An external arrangement the quick exhaust valve would of course also be possible if for Should be vented to the environment. For reasons described above however, this is undesirable.

In a preferred embodiment of the invention, the valve device is for Quick exhaust, however, within the pipe or pipe section arranged, which is part of the cable routing within the spring chamber forms. This has the particular advantage that those forming the branch channel Passage openings in the pipe forming the conduit directly can be arranged near the spring chamber side of the piston, which means a shortest connection path for the overflow process between the pressurization chamber and the spring chamber. Since the Valve device expediently directly with the passage openings interacts, it can also be within the tube in immediate Provide near the piston.

The pipe arranged in the part of the conduit Valve device expediently has an axial inside the tube Directional control part, which in the rest position by a elastic member, for example a compression spring, against a stop is held and in this position the passage openings in the Spring chamber closes. If there is overpressure from the side of the Percussion piston is the control part against the restoring force of the elastic Link movable back to the passage openings in the spring chamber to release. The control part is preferably part of a Control piston arrangement through which the described control functions be carried out automatically.

To the pressure medium for the operation of the knocker by the To be able to supply connecting channel to the pressurization chamber contains the spool assembly flow channels, which is a check valve included, which is present when the supply line is vented and as a result Overpressure from the side of the percussion piston and through the control part released flow openings in the spring chamber due to the excess pressure closes from the piston side, with overpressure from the supply port for the But the print medium opens.

The beating cycle of knockers of the type described here is common in many Cases by a 3/2-way valve arranged in the supply line for the pressure medium controlled. In this embodiment, the frequency is determined by the Valve control specified. The arrangement of such an external valve is shown schematically in DE-A 38 19 111 and described. Pneumatic knockers can also be operated automatically Control internally installed means, as described in DE-A 38 19 112 is. The control of the supply of the pressure medium is in the generally made by the piston itself, which by Movement play releases or closes certain control openings. The Means of self-control, as described in DE-A 38 19 112, can be used in an analogous manner on the pneumatic described here Knockers transferred, because narrower for the supply of the print medium Flow channels can be accepted.

To ensure the entry of outside air into the spring chamber prevent, is for an overpressure compensation of the spring chamber Appropriately provided vent opening also expediently provided with a check valve, which at higher ambient pressure closes and thus the inflow of ambient air into the spring chamber prevented. This check valve can, for example, as Ball check valve formed and in an additional plate, e.g. out an elastomer, may be arranged on the inside of the spring chamber side Housing end wall is arranged. This design avoids the valve is to be built into the end wall of the housing. In this only a small hole needs to be provided, either aligns directly with the ball check valve or one elsewhere Opposite ring groove in the additional plate, in which the check valve opens.

For the sealed guidance of the piston in relation to the housing jacket and also, if necessary, compared to the one projecting into the axial bore of the piston For oil-free operation, pipes are expediently made of PTFE sealing rings intended. Since these are difficult to use, particularly in internal grooves, it is expedient to in the percussion piston in the place of such sealing ring grooves Execute radial planes divided, the parts of the piston being arranged the sealing rings can be screwed together.

Pneumatic knockers are usually on the side of the Pressurization chamber open and with one Provide mounting flange in which a ring seal is inserted. The required counter surface for sealing the pressurization space is formed by a wall of the object with which the knocker is screwed tight. Between this object and the flange can be also provide a spacer plate, the middle area of which by a Elastomer insert is formed. Such an elastomer insert can also be used without Spacer plate inserted in the piston end of the knocker or in the Front of the piston itself.

The elastomer insert forms a softer stop surface for the piston.

Fig. 1

eine teilweise längsgeschnittene schematische Ansicht eines pneumatischen Klopfers,

Fig. 1a

eine vergrößerte Ansicht der Entlüftungseinrichtung ... für den Federraum des Klopfers nach Fig. 1,

Fig. 2

eine teilweise geschnittene Längsansicht des Kolbens und des Schnellentlüftungsventils des Klopfers nach Fig. 1 im Zustand der Schnellentlüftung,

Fig. 3

eine weitere Ausführungsform eines pneumatischen Klopfers, bei der sich das Schnellentlüftungsventil in einem mit dem Kolben, mitgeführten Rohr befindet,

Fig. 4

eine weitere Abwandlung des Klopfers nach Fig. 3, bei der das mit dem Kolben mitbewegte Rohr endseitig durch die Gehäusestirnwand hinausgeführt ist, und

Fig. 5

eine spezielle Ausbildung der federraumseitigen Gehäusestirnwand mit eingebautem Rückschlagventil.

In the following the invention is further explained with reference to the accompanying drawing. In the drawing:

Fig. 1

2 shows a partially longitudinally sectioned schematic view of a pneumatic knocker,

Fig. 1a

2 shows an enlarged view of the ventilation device ... for the spring chamber of the knocker according to FIG. 1,

Fig. 2

2 shows a partially sectioned longitudinal view of the piston and the quick exhaust valve of the knocker according to FIG. 1 in the quick exhaust condition,

Fig. 3

another embodiment of a pneumatic knocker, in which the quick exhaust valve is located in a tube carried with the piston,

Fig. 4

a further modification of the knocker according to FIG. 3, in which the tube moved with the piston is led out through the end wall of the housing, and

Fig. 5

a special design of the housing end wall on the spring chamber side with built-in check valve.

In Fig. 1, a pneumatic knocker is partially schematic in longitudinal section shown. The knocker has a housing 2, which consists of a cylindrical housing shell 4, an end wall 6 at one end of the Housing shell and a flange 8 at the other, open end of the Housing shell 2 is made. The flange 8 is with an annular seal 10 its outside and provided with screw holes 12 on its circumference. By means of the flange 8, the knocker is thus sealing against the wall of a Screw-on object that is to be exposed to knocking. You can choose between the knocker and this, for example Subject still provide a spacer plate 14, which in its interior with an elastomer insert 16 is provided. Such an elastomer insert dampens the piston knocks to some extent and contributes to the extension the lifespan of the knocker and the stop surface as well as significantly Noise reduction at.

The knocker also has a percussion piston 18, which means Ring seals 20, which are inserted in grooves of the percussion piston, slidable in, Housing jacket 4 is guided. The (based on the graphic representation) upper end face 22 of the percussion piston 18 is provided with a recess 24, in which a coil spring 26 is supported at one end while you the other end abuts against the end wall 6 of the housing 2 located above. The through the housing shell 4, the upper end face 22 of the percussion piston and the housing end wall 6 limited space is referred to as spring space 28 which Upper housing end wall 6 also as a housing end wall on the spring chamber side.

Instead of a single coil spring 26, for example Concentric multiple spring arrangements can be provided.

The percussion piston 28 has a continuous, central axial bore 30 Mistake. On the other hand, with the end wall 6 of the housing by means of a Nut 32 a pipe 34 passed through this against one Screwed locking ring, which with its free lower end in the central bore 30 of the piston protrudes and in this also by in the wall of the piston bore 30 embedded sealing rings 36 sliding and is performed sealing. The tube 34 extends so far into the lower part of the Knockers in that the sealing rings 36 in the entire movement of the Remain effective. The percussion piston 18 has a lower end face 38 on. Through this end face 38, the housing shell 4 or the inside of the Flange 8 and a counter surface, not shown, of the object with which the knocker is screwed, delimits a pressurization space 40 for the percussion piston. The interior of the tube 34 forms one Connection channel 42 between a (not shown in detail) Supply connection for the compressed air at the upper end of the tube 34 at the arrow 44 into the pressurization chamber 40. In an area of the pipe 34, which at no time during piston play is covered by the percussion piston there are openings 46 in the spring chamber 28 in the wall of the tube 34 provided that form a branch channel of the connecting channel 42.

In the area of these openings 46 there is an automatic inside the tube 34 Valve device 48 is provided. This valve device consists of a Control piston 50 which is arranged axially slidable in the upper part of the tube 34 and against which one is supported in the area of the end wall 6 of the housing Spring 52 is present. The movement play of the control piston 50 is down limited by a stop 54 on the inner wall of the tube 34. in the The piston 50 is at rest by the spring 52 against this stop 54 pressed and closes the outer surface of the Breakthroughs 46 in the tube 34. The control piston 50 is stepped axial through bore 56 provided, in the training known per se a ball check valve 58 is arranged. This ball check valve 58 is aligned in such a way that it comes from the connection with incoming compressed air 44 forth opens, with a positive pressure difference from the Pressurizing chamber 40, however, closes.

The spring chamber 28 is essentially hermetically sealed, but it is an air outlet opening 60 is provided in the housing jacket 4, which the degradation an overpressure in the spring chamber 28 allowed when the piston against the Coil spring 26 is moved back. As from the enlargement of Fig. 1a can be seen, is also in the air outlet opening 60 Check valve 62 is arranged, which allows the outflow of pressurized air allows outside air to enter the spring chamber prevented.

The following is the operation of the above pneumatic knocker briefly explained, it being assumed that the in Fig. 1 knockers not shown in its pressurization or frequency automatically controlled internally but externally. For this purpose the Knocker at the location of arrow 44 provided with a compressed air connection, in which is a frequency controlled 3/2-way valve. Not through this shown valve, the knocker is intermittently pressurized with compressed air, i.e. compressed air is allowed to flow into the knocker. With ventilation the blow takes place.

The compressed air supplied passes through the valve device 48, which in the In the idle state, the openings 46 in the tube 34 are closed when the opening is open Ball check valve 58 in the control piston 50 directly into the Pressurization chamber 40 and presses the percussion piston 18 against the Return force of the coil spring 26 upwards. The percussion piston 18 is in brought an equilibrium position by the pressure of the supply compressed air and depends on the spring.

At the moment when the supply compressed air is not only switched off but the supply line is also vented, prevails above the control piston 50 Ambient pressure, while at the bottom of the spool the increased Pressure on the pressurization chamber 40 is present. By the Differential pressure, the ball check valve 58 is closed and thereby the Control piston pushed up against spring 52 until it breakthroughs 46 releases. This state is in the components shown in Fig. 2 identified. The black arrows in FIGS. 1 and 2 represent the momentary piston movement and the white arrows represent the air movement.

The fact that the rapidly moving percussion piston 18 in Spring chamber 28 generates a negative pressure, the overflow of air takes place the pressurization chamber 40 in the spring chamber 28 takes place even faster. As can easily be seen from FIGS. 1 and 2, the overflow air can practically the shortest path between pressurization chamber 40 and take spring chamber 28. The connecting channel 42 in the form of the tube 34 has a sufficient flow cross section and also the openings 46 in the wall of the tube 34 can be sized accordingly large. Of the Control piston 50 is not in this flow path, as in FIG. 2 emerges. The fact that the spool 50 has only one channel inside has a smaller cross section, does not interfere with the effect according to the invention, because for the inflow of new compressed air and in relation to the blow of the Piston submits a relatively long time when it is exposed to energy smaller cross section for the supply of compressed air.

Fig. 3 shows a modified embodiment of a pneumatic knocker In this embodiment, instead of the tube 34 is the Embodiment according to FIGS. 1 and 2 a pipe or rather a pipe section 64 provided, which is fixed to the percussion piston 18, with its upper Front side (based on the graphic representation) is connected. This Pipe section 64 is only a piece in the for the purpose of its attachment Percussion piston 18 inserted. The channel formed by the pipe settles within the piston as an axial channel through a bore 66th is formed, the diameter of which is approximately that Corresponds to the diameter of the tube 64. By means of a transition piece 68 attached to the upper end of the tube 64 a metal bellows 70, the other end on the inside of the upper end wall 6 of the housing is appropriate. In him in the end wall 6 of the supply port 72 for the compressed air. The metal bellows 70 is for the prints used designed to be pressure-resistant. The spring constant of the metal bellows can be so be chosen so that they store the energy of the compression spring 26th can support. The valve device 48 in the embodiment of FIG FIG. 3 corresponds to that in the embodiment according to FIG. 1 educated. Since in the embodiment according to FIG. 3 the pipe section 64 is firmly connected to the percussion piston 18, this embodiment has the Advantage that the openings designated 46 there in the wall of the Pipe section immediately above the top of the percussion piston 18th can be arranged so that even when the percussion piston 18 is moving the shortest flow path between the pressurizing space 40 and the spring chamber 28 can be maintained.

In the embodiment according to FIG. 4, the pipe section 64 is instead of the Metal bellows of the embodiment of FIG. 3 in turn with a connected further pipeline 74 which is slidable through an opening in the end face 6 of the housing is passed through. This pipe 74 can be rigid, but also have a certain flexibility. At this The embodiment is the movement of the percussion piston 18 over the Pipeline 74 in an area outside the knocker housing transfer. If this pipeline outside the housing is still a knee has for fastening a compressed air connection, as shown in FIG. 4 is shown, there is a possibility that a person at the Impact execution between pipe 74 and the end wall 6 of the housing can jam. The embodiment according to FIG. 4 is therefore not considered to be particularly preferred.

2 shows the cut area of the percussion piston 18, that the piston in its lower portion in the area of the sealing rings 20 and 36 is divided in a horizontal plane 76. The piston parts are screwed together by screws 78. PTFE sealing rings, the preferably used with oil-free compressed air and / or higher temperatures are very difficult, especially in internal grooves in bores bring in, which is why the split version of the piston here Assembly aid offers. The grooves for the inner and outer seal are included expediently placed so that they are in the same area Division level fall. If the compressed air is oiled, the one-piece piston can be Fig. 1 can be used.

Fig. 5 shows a modified cylinder head, in one Elastomer plate 78 is inserted. The check valve for venting the Spring chamber is here as a check valve 80 in the elastomer plate housed. The ventilation itself does not take place directly at the point of the Check valves through the housing end wall 6 instead takes place over a Annular groove 82 to a vent 84 elsewhere in the Housing end wall 6. The check valve 80 designed as a ball valve leaves so easy to train and assemble. The valve ball can be loose in one corresponding recess in the elastomer plate 78 are inserted.

Claims (14)

Pneumatic knockers with a housing with a casing jacket and at least one end wall, a percussion piston slidably arranged in the housing in the axial direction of the housing shell, one essentially through a first end face of the piston, the housing jacket and the spring space delimiting at least one housing end wall, a compression spring arrangement arranged in the spring chamber and supported on the one hand on this first end face of the piston and on the other hand on the housing, a pressurization space essentially delimited by the second end face of the piston, the housing jacket and a counter surface fixed to the housing, a feed connection for pressure medium passed through the housing, a connection channel for the pressure medium from the supply connection to the pressurization chamber and an automatic valve device assigned to the connecting channel with a branch channel in the spring chamber for shutting off the connecting channel from the supply connection and for establishing an overflow connection between the pressurizing chamber and the spring chamber,
characterized in that the connecting channel (42) for the pressure medium has a substantially rectilinear main section (66) (pipe 34, 64) which, starting from the pressurizing chamber (40), starts from an axial channel (66) through the percussion piston (18) and an adjoining this pipeline (tube 34, 64) in or through the spring chamber (28), and that the branch channel is formed from passage openings (46) in the wall of this pipeline. Pneumatic knocker according to claim 1, characterized in that the cable routing consists of a tube (34), on the one hand Fixed to the housing with the housing end wall (6) on the spring chamber side and on the other hand in an axial bore (30) of the percussion piston (18) continued and guided in this sealed (36) slidably. Pneumatic knocker according to claim 1, characterized in that the conduit has a tube (64) which reads with the Percussion piston (18) is connected. Pneumatic knocker according to claim 3, characterized in that the tube (64) at its other end with a pressure resistant Bellows (70) is connected, the other end with the Spring chamber-side housing end wall (6) is connected. Pneumatic knocker according to claim 3, characterized in that the tube (64, 74) seals and slides through the spring chamber side Housing end wall (6) passed and on its outside the Housing located end with the feed connector for the Media is provided. Pneumatic knocker according to at least one of claims 2-5, characterized in that the two-channel Passage openings (46) in the wall of the tube (34, 64) Cable routing are formed and directly in the spring chamber (28) open. Pneumatic knocker according to claim 6, characterized in that the automatic valve device (48) within the tube (34, 64) Cable routing is arranged. Pneumatic knocker according to claim 6 and 7, characterized characterized in that the valve device has a control part (50), which limits the pipe routing within the pipe (34, 64) axially displaceably sealingly guided and formed, the Open or close through openings (46) of the two-channel close. Pneumatic knocker according to claim 8, characterized in that the control part is part of a control piston arrangement (50) which is under the pretension of an elastic member (52) which the control part (50) in the idle state against a stop (54) is held in a position closing the two-channel (46), however with a positive differential pressure on the part of Pressurization chamber (40) forth against the restoring force of the elastic member (52) in the direction of the feed connection (44, 72) for the print medium in a release position for the two-channel (46) is movable. Pneumatic knocker according to claim 8 or 9, characterized characterized in that the control piston arrangement (50) is axial Contains flow channels (56) with a check valve (58) which with positive differential pressure from the side Pressurization chamber (40) comes into the closed position. Pneumatic knocker according to at least one of claims 1-10, which the spring chamber (28) except for an outflow device (60, 62) communicates with the environment, is sealed pressure-tight. Pneumatic knocker according to claim 11, characterized in that the outflow device is designed as a check valve (62). Pneumatic knocker according to at least one of claims 1-12, characterized in that the housing-fixed counter surface of the Pressurizing space (40) by an external object is formed with which the housing (2) of the pneumatic knocker is connected pressure-tight. Pneumatic knocker according to at least one of claims 1-13, characterized in that the percussion piston (18) in the outer area and / or if necessary, inner sealing ring grooves (20, 36) are designed to be divided and the parts together, for example by screwing (78) are connectable.

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