EP1607187A1 - Method and device for improving the deactivation response of an electropneumatic percussive tool - Google Patents

Abstract

The method involves increasing the pressure between the fly piston (14) and exciter piston (12) when the drill is lifted away from the ground in order to reduce the knock-on effect of the fly piston. Independent claim describes excavating machine such as a drilling hammer which has a valve mechanism (30) which can be activated when the machine is lifted from the substrate so that the pressure in the impact mechanism (10) acting between the fly and exciter piston is increased.

Description

The invention relates to degradation equipment with electropneumatic Drive, in particular on electropneumatic rotary and / or chipping hammers. It relates in particular to a method and a device for Improvement of the shutdown behavior of such mining equipment.

In devices of the type mentioned by an electric motor is an exciter piston powered, which one via a pressure shock pad (hereinafter "Air spring") coupled flight piston periodically reciprocating stimulates. Due to the impact of the flying piston on a in a tool holder held removal tool or via an interposed Döpper is generated in the tool a shock wave, which the Destruction of the subsurface causes.

Will the mining tool in chisel or hammer drilling operation lifted off the ground, so should the electropneumatic percussion be deactivated as quickly as possible after taking off the generated by the flying piston and running along the tool shock wave can no longer be absorbed by the subsoil; she will completely reflected. The entire shock wave energy must be in this Case taken by the structure of the mining equipment and the user become. Not just the returning wave, but especially the first Shockwave after lifting must be done by re-storing the tool holder be recorded. Usually provide special damping elements for that by repeatedly looking up the flying-piston no damage to the structure arise. However, these too Damping and structural elements of the device are not designed or interpretable that the entire chisel power for a long time without lasting Damage could be absorbed. The consequences of too slow Turn off the percussion after lifting off the ground are a relatively high material wear and of course unpleasant and harmful vibrations to the arms, joints and overall Body of the user.

(a) Das aktive Schlagwerk: Luftablassöffnungen in der Luftfeder werden geöffnet.

(b) Das passive Schlagwerk: Die Luftfeder wird beim Abheben des Geräts verlängert und dadurch weich.

(c) Das schnelle Abschalten des Antriebs, eventuell unterstützt durch schnelles, aktives Abbremsen des Antriebs.

Basically, the following methods are known to disable an electro-pneumatic percussion mechanism when interrupting or ending a work process and lifting the device from the ground:

(a) The active hammer mechanism: Air exhaust holes in the air spring are opened.

(b) The passive impact mechanism: The air spring is extended when lifting the unit and thus soft.

(c) Quick shutdown of the drive, possibly supported by fast, active braking of the drive.

The method (a) is realized in practice so that when lifting the Device from the underground the tool and the club around Millimeter to centimeter from the user to move forward. This axial movement is transmitted to a control sleeve, which

Air outlet openings on the guide tube opens. This causes a big one Leakage in the air spring and thus a pressure equalization to the atmospheric pressure. The excitation piston is now no longer in the return stroke able to create a negative pressure and to suck the air piston again. The percussion is deactivated.

Also in the method (b), the path of the bonnet or tool in Lifting the device from the ground used, but not by one To control sleeve, but to the striking mechanism or its air spring extend. The extension of the effective percussion length to the Döpperweg causes the air spring is so soft that the flying piston is not sucked again during the return stroke of the exciter piston.

Method (c) requires a dynamic drive. The most frequent Drive type in power tools of the type mentioned is nowadays the Universal motor. This type of engine can not be actively braked - it is because of a very complex arrangement by turning the current direction in the stator package. As soon as the excavator is lifted off the ground is switched off, the engine is switched off. When re-pressing the Tool to the ground, the speed is driven up again.

Common to all three methods is that one lookup still occurs or at least can occur. Depending on the friction conditions on the wall of the guide tube in the percussion and At the sealing elements of the flying piston, it can in all known Methods occur that the flying mass once it has been deactivated repeatedly hit the striker. The stuck in the flying piston kinetic energy can only be due to the friction with the lateral surfaces of the guide tube, by collisions with the striker or through Compression of the residual content of air absorbed and degraded. In this respect, these are purely passive procedures. The flying piston loses its kinetic energy through shocks or friction.

The invention is based on the object, the shutdown and in particular Look-up behavior of electro-pneumatically operated mining equipment, especially of drills and / or chisel hammers to improve.

The inventive method for improving the Nachschlagverhaltens an electropneumatic degradation device, in particular a Drill and / or chipping hammer, in which within a guide tube via an air spring by an electrically driven excitation piston accelerated flying piston acts on a mining tool is according to the invention characterized in that to reduce the lookup of the flying piston when lifting the dismantling device from the machined Underground the pressure between the flying piston and the excitation piston is increased.

The invention thus relates to an active method for stopping of the flying piston, as soon as the tool or the removal device from the underground is lifted. This is in the electro-pneumatic percussion creates an overpressure that moves the flying lobe forward in the direction of Dappper or tool accelerates. Only when re-preparing the Device, the pressure is reduced and the percussion begins again to work normally.

According to the invention, a mining device with electro-pneumatic striking mechanism, in particular a drill and / or chisel hammer, the hammer mechanism an electrically forward and backward within a guide tube driven exciter piston, which has one of this compressed air spring accelerates a flying piston, which in turn a striking tool held in a tool holder, characterized by a to be dismantled when lifting the mining equipment Underground activatable valve device, over which the between increases the pressure acting on the flying and exciter pistons in the striking mechanism becomes.

According to a first advantageous embodiment variant, the valve device a check valve, on the lifting of the Tool from the underground during the return stroke of the exciter piston between this and the air piston resulting negative pressure on a higher pressure, in particular ambient pressure is raised. Preferably has the guide tube in the region of the air spring at least a bore, also referred to herein as a "puff hole," and the check valve is displaceable relative to the guide tube and arranged so that when lifting the excavator from the ground by a Adjustment is aligned with the bore.

In an advantageous embodiment of the invention, the check valve integrated into a control sleeve surrounding the guide tube, which is displaceable by the adjusting device. If - like one preferred embodiment provided - the driven via the air spring Flying piston hitting on a tool holder associated Döpper acts, is the adjustment of the check valve preferably by the striker moving forward when lifting actuated. In this case, the control sleeve by the adjustment relative to the guide tube either axially displaceable or relative to Be designed guide tube rotatable. A spatially favorable, because space-saving design embodiment can then be realized if the preferably integrated in the control sleeve check valve Flap valve or a ball valve is. An integrated into the control sleeve Flap valve, for example, by a cantilevered, extending transversely to a passageway in the control sleeve extending Be formed leaf spring. The solution with integrated in the control sleeve Ball valve has the advantage that the bias and thus the Release pressure of the check valve via a force acting on a compression spring Set the adjusting screw well.

Another basic embodiment of the invention for preventing looking up the flying piston sees the use an accumulator device, by the activation of the valve device at the time of work stoppage and raising the Tool the pressure in the percussion is increased. The accumulator can be actuated via the exciter piston drive pump, for example an actuated by the connecting rod drive of the exciter piston reciprocating pump his. An elegant and space-saving solution then results when the pump is operated as one by the drive of the exciter piston Eccentric pump is realized, wherein an eccentric of the connecting rod drive act as a piston and the surrounding housing as a pump housing.

A further basic embodiment variant of the invention provides the valve device by means of at least one actively switched valve, for example, an electromagnetically actuated valve, such as in To realize the shape of a dynamic valve sleeve valve. The valve is in particular by an electromagnetically actuated Control sleeve formed in a switching position at least one of the guide tube closing through hole to the air spring closes and in releases another shift position. Another tried and tested The solution for a dynamic valve sleeve valve is the Control sleeve relative to the guide tube of the striking mechanism axially by a To move the voice coil actuator whose displaceable core through the Control sleeve is formed.

Fig. 1

die Prinzipdarstellung eines Bohr- und/ oder Meisselhammers mit elektropneumatischem Schlagwerk, das erfindungsgemäß mit einer pneumatischen Flugkolbenbremse ausgestattet ist;

Fig. 2 mit Teilfiguren 2A und 2B

die Prinzipdarstellung eines elektropneumatischen Schlagwerks für Geräte der genannten Art mit einer aktiven Flugkolbenbremse, realisiert mittels durch eine Steuerhülse axial verschiebbarer Klappenventile, wobei
Fig. 2A die Position des Klappenventils in der Arbeitsposition des Geräts, also beim Abbau von Untergrund zeigt, während
Fig. 2B das Klappenventil bei vom Untergrund abgehobenem Werkzeug, und damit aktivierter Flugkolbenbremse veranschau- licht;

Fig. 3A

die isometrische Darstellung einer erprobten Steuerhülse mit integrierten Klappenventilen zur Deaktivierung und Aktivierung der Flugkolbenbremse;

Fig. 3B

die Schnittdarstellung der Steuerhülse nach Fig. 3A;

Fig. 4

die Schnittdarstellung einer Steuerhülse mit integrierten Kugelventilen als Rückschlagventile;

Fig. 5

die Prinzipdarstellung eines elektropneu- matischen Schlagwerks, ausgerüstet mit einer Steuerhülse mit Kugelventilen gemäß Fig. 4;

Fig. 6

die Prinzipdarstellung eines elektropneu- matischen Schlagwerks mit aktiver Flug- kolbenbremse gemäß der Erfindung zur Verdeutlichung des Begriffs "effektive Schlagwerkslänge";

Fig. 7 mit Teilfiguren 7A, 7B und 7C

die Prinzipdarstellung eines elektropneumatischen Schlagwerks mit aktiv steuerbarem Rückschlagventil, dargestellt in drei unterschiedlichen Positionen zur Veranschaulichung eines nachfolgend erläuterten Betriebsverhaltens;

Fig. 8

drei zeitkorreliert übereinander dargestell- te Signaldiagramme zur Veranschauli- chung eines Stopp- und Startvorgangs eines elektropneumatischen Schlagwerks mit erfindungsgemäßen Merkmalen bei kurzzeitiger Unterbrechung und Wieder- aufnahme eines Arbeitsvorgangs mit dem Abbaugerät;

Fig. 9

eine zeitlich auseinandergezogene Darstellung der Messsignaldiagramme der Fig. 8 zur Veranschaulichung des Abschalt- bzw. Nachschlagverhaltens eines elektropneumatischen Schlagwerks mit erfindungsgemäßer Flugkolbenbremse;

Fig. 10

die ebenfalls zeitlich auseinandergezogene Darstellung eines Teilabschnitts der Messsignale aus Fig. 8 zur Verdeutlichung des Anlaufverhaltens des Schlagwerks gemäß der Erfindung;

Fig. 11

eine der Fig. 8 entsprechende zeitkorrelierte Darstellung von drei Messsignalen zur Verdeutlichung eines Stopp- und Startvorgangs eines elektropneumatischen Schlagwerks, bei dem zusätzliche Maßnahmen getroffen sind, um einen beim raschen Abbremsen des Flugkolbens erzeugten Überdruck im Schlagwerk rasch abzubauen;

Fig. 12

eine zeitlich gestreckte Detaildarstellung aus der Graphik der Fig. 11 zur besseren Verdeutlichung des Anlaufverhaltens des Schlagwerks bei zusätzlichem Abblasen des für den Abbremsvorgang aufgebauten Druckpolsters;

Fig. 13

eine Ausführungsform der Erfindung, bei der die Flugkolbenbremsung durch Aufbau eines Zusatzdrucks über einen durch eine Hubkolbenpumpe aufladbaren Druckspeicher erfolgt;

Fig. 14

eine andere Ausführungsvariante, bei der ein Druckspeicher über eine vom Pleuel des Erregerkolbens mitbetätigte Exzenterpumpe aufgeladen wird;

Fig. 15

eine Ausführungsvariante der Erfindung, bei der eine Druckerhöhung im Schlagwerk bei Arbeitsunterbrechung über ein schaltbares Ventil, vorzugsweise Zweiwegeventil, erfolgt; und

Fig. 16

eine Ausführungsvariante der Erfindung, bei der eine Steuerhülse zur aktiven Öffnung von Schnauflöchern im Bereich der Luftfeder bei Arbeitsunterbrechung und Abheben des Werkzeugs vom Untergrund durch einen Voice-Coil-Aktor axial hinund hergeschoben wird.

The invention and advantageous details thereof are explained in more detail below with reference to the drawings in exemplary embodiments. Show it:

Fig. 1

the schematic diagram of a drill and / or chisel hammer with electropneumatic impact mechanism, which is equipped according to the invention with a pneumatic air piston brake;

Fig. 2 with sub-figures 2A and 2B

the schematic diagram of an electro-pneumatic percussion mechanism for devices of the type mentioned with an active air piston brake, realized by means of a control sleeve axially displaceable flap valves, wherein
Fig. 2A shows the position of the flap valve in the working position of the device, ie during the degradation of underground, while
FIG. 2B illustrates the flap valve when the tool is raised from the ground and the air piston brake is activated; FIG.

Fig. 3A

the isometric view of a proven control sleeve with integrated flap valves for deactivation and activation of the aircraft piston brake;

Fig. 3B

the sectional view of the control sleeve of FIG. 3A;

Fig. 4

the sectional view of a control sleeve with integrated ball valves as check valves;

Fig. 5

the schematic diagram of an electropneumatic impact mechanism, equipped with a control sleeve with ball valves of FIG. 4;

Fig. 6

the schematic diagram of an electropneumatic percussion with active piston piston brake according to the invention to illustrate the term "effective percussion length";

Fig. 7 with sub-figures 7A, 7B and 7C

the schematic diagram of an electro-pneumatic percussion with actively controllable check valve, shown in three different positions to illustrate a subsequently explained operating behavior;

Fig. 8

three time-correlated signal diagrams to illustrate a stop and start operation of an electropneumatic impact mechanism with features according to the invention in the case of brief interruption and resumption of a work operation with the dismantling device;

Fig. 9

a time-separated representation of the measurement signal diagrams of Figure 8 to illustrate the shutdown or Nachschlagverhaltens an electropneumatic percussion with inventive aircraft piston brake.

Fig. 10

the likewise temporally exploded view of a portion of the measurement signals of Figure 8 to illustrate the start-up behavior of the percussion mechanism according to the invention.

Fig. 11

8 corresponding time correlated representation of three measuring signals to illustrate a stop and start operation of an electropneumatic impact mechanism, in which additional measures are taken to rapidly reduce a generated during rapid deceleration of the air piston overpressure in percussion;

Fig. 12

a time-extended detail from the graph of Figure 11 for better clarity of the start-up of the percussion mechanism with additional blowing off the built-up for the braking pressure pad.

Fig. 13

an embodiment of the invention, in which the air piston brake is done by building up an additional pressure via a pressure accumulator can be charged by a reciprocating pump;

Fig. 14

another embodiment in which a pressure accumulator is charged via a co-operated by the connecting rod of the exciter piston eccentric pump;

Fig. 15

an embodiment of the invention, in which an increase in pressure in the impact mechanism at work interruption via a switchable valve, preferably two-way valve occurs; and

Fig. 16

an embodiment of the invention, in which a control sleeve for the active opening of Schnauflöchern in the region of the air spring at work interruption and lifting the tool from the ground by a voice coil actuator is pushed axially back and forth.

Corresponding components or assemblies are in all figures indicated with the same reference.

Fig. 1 shows a schematic side sectional view of a mining device with features of the invention, in the example shown a Drill and / or chisel hammer 1, whose housing is divided by two parts is formed, namely a handle shell 2 and a motor housing shell. 3 However, this division of the housing is not mandatory; there are others one-, two- or multi-part housing enclosures for devices of this type. In the grip area of the handle housing shell 2 you can see a push-button. 4 for the ON / OFF switching, which in certain operating modes via a Potentiometer switch simultaneously to the engine speed or Torque adjustment can serve. The power supply is via a connection cable 6. Different operating modes, especially the area code for pure drilling operation, drilling hammer operation or pure chisel operation and optionally for fine boring, fine chisels, etc., are on a selector switch 8 possible whose default values one only schematically indicated motor control or regulation 7 are supplied.

The drive motor is of conventional design and is for reasons of Clarity not shown. The mining equipment has an electropneumatic Schlagwerk 10 with a guide tube 11, in its behind a range exciter piston 12 by a connecting rod drive 13 hin- and is driven forth or back and forth. The exciter piston 12 acts via an air spring 19 on a flying mass 14, his transfers kinetic energy via a pressure pad 21 to an anvil 15, which in turn strikes axially in a tool holder 9 held tool, in particular a chisel (not shown), acts. In the context of the invention, the pressure pad 21 is not mandatory. In principle, it is also possible that the flying piston 14 directly on the Tool or acts directly on the striker 15.

Essential to the invention is a generally by reference 30th specified pneumatic air piston brake to generate an overpressure between the excitation piston 12 and the flying mass 14, which causes that the flying mass 14 when settling the excavator from the ground pressed against the striker 15. This is the return stroke the excitation piston 12, a negative pressure in the air spring 19 and thus a Looking up the flying piston 14 avoided.

In the in Fig. 1 only schematically and in Figs. 2A, 2B shown more clearly Embodiment variant is a control sleeve 17, too referred to as "pump-up sleeve", the hammer or chisel operation of Dismantling device in the position illustrated in Fig. 2A, in which Schnauflöcher 18 through an annular closed portion of Control sleeve 17 are closed. Is the mining equipment from the ground discontinued, so the striker 15 slips by a length .DELTA.x of a few Millimeters to a centimeter maximum by 2.5 cm forward in Direction of the tool. About the coupled with the striker 15 adjustment the control sleeve 17 is also moved axially forward, so check valves, here designed as flapper valves 20 are aligned with the Schnauflöcher 18. Moves the exciter piston 12 now backwards, so that in the space of the air spring 19 creates a negative pressure would, so open the flap valves 20. This allows the pressure in the air spring 19 is not or not significantly below atmospheric pressure fall. The flying mass 14 is no longer sucked in and stays on or standing in front of the stopper 15.

The isometric view of Fig. 3A shows an enlarged view a proven embodiment for the axially displaceable control sleeve 17. This control sleeve 17, preferably produced as a plastic molding is, consists - as the Fig. 3B reveals - from a sleeve ring 21 with a number corresponding to the number of Schnauflöcher 18 plurality of recessed axial chambers 24 into which the flap valves 20 are used, and held by a screw 26 sealing become. The axial chambers 24 are each about an opening 25, the number of which corresponds to the number of Schnauflöcher 18, with the interior of the control sleeve in conjunction. The flap valves 20 essentially consist of one cantilever each Leaf spring element 22, the one inlet / outlet opening 27 depending on the pressure conditions on one side or the other of the leaf spring element 22 releases or closes. The hardness of the leaf spring element 22 determined the response of the flap valve 20th

Fig. 4 shows another proven embodiment for the control sleeve 17. Instead of the flap valves 20 ball valves 28 are provided here, which release the openings 25 or close. The Responsiveness of this valve type can be sensitively via a set screw 31 Adjust over which the bias one on the ball valve acting compression spring 29 is determined. The advantage of this design with ball valves is a simpler manufacturing process because the control sleeve 17 are largely completely manufactured as an injection molded part can, as well as a good adjustability of the valve bias and thus the response of the check valves.

Fig. 5 shows an embodiment of the electro-pneumatic impact mechanism 10, equipped with the ball valve sleeve of FIG. 4 as a control sleeve 17. Incidentally, the embodiment of FIG. 5 corresponds to that FIGS. 2A and 2B, respectively, so that further explanation is unnecessary can.

Fig. 6, which in turn shows the already explained electro-pneumatic percussion, but in this case only with schematically indicated control sleeve 17, serves to explain a mathematical estimate of the maximum achievable pressure and effective acting forces, in Fig. 6, the term used below l _{eff of} the "effective percussion length" is registered and illustrated.

In the underlying method of the invention, in short as "Pump-up procedure", are called at the moment of switching off the Schlagwerks - as already explained - connected check valves, the are directly connected to the air spring 19 of the percussion and this inflate by that during the backward movement of the exciter piston 12, a negative pressure in the air spring 19 is formed. The inside directed check valves, such as the flap valves 20 or the ball valves 28, are opened and it becomes air mass in the interior the air spring 19 sucked. Once the exciter piston 12 his Moving direction changes, these check valves are closed and the air is compressed. This creates an overpressure in the Schlagwerk, the flying piston 14 forward, towards Döpper 15 suppressed. The air piston 14 remains characterized after a short time in the foremost Standing position.

In the following, the mean pressure is to be estimated, which is so in the Schlagwerk is generated to illustrate that the forces are sufficient the flying mass 14 within a short time forward in the direction Accelerate tool.

If it is permissible to assume that the check valves close at the time when the excitation piston 12 changes its direction of movement, ie at the rear dead center position, then the maximum pressure generated in the impact mechanism can be estimated. The pressure in the impact mechanism is just as great at this time as the external atmospheric pressure po. The stroke of the exciter piston 12 amounts to h _EK . The air mass in the impact mechanism is compressed around this stroke. It is legitimately assumed that the gas (the air) in the impact mechanism behaves ideally isentropically (adiabatically) with a coefficient κ = 1.4. It then applies:

The maximum pressure is thus given by: p Max = p 0 · ( l eff + H EK l eff ) κ

l_eff: effektive Schlagwerkslänge; (vgl. Fig. 6)

po: äußerer Atmosphärendruck

h_EK: Hub des Erregerkolbens

κ: Isentropen-Koeffizient; κ = 1.4 für Luft.

In this mean:

l _eff : effective percussion length; (see Fig. 6)

po: external atmospheric pressure

h _EK : stroke of the exciter piston

κ: isentropic coefficient; κ = 1.4 for air.

Assuming that the exciter piston stroke corresponds approximately to the effective percussion length, ie h _EK = l _eff , this results in a maximum pressure which is slightly more than twice as high as the external atmospheric pressure p 0: p Max ≈2 κ p 0 ≈2.6 · p 0

The force with which the flying mass 14 is accelerated forward is given by:

If the time-dependent instantaneous position of the excitation piston is denoted by x _EK (t), the following applies:

It follows from Eq. (4)

The mean force results from an averaging over a field piston period:

Therein A denotes the end face of the exciter piston and T the Period of an exciter piston cycle.

The integral of equation (7) can not be easily solved analytically because of the exponent κ. Therefore, two simplifications are considered. The first is to remove the exponent from the integrand. You then get:

This results in an average force of:

und eine mittlere Beschleunigung von a = F m FK ≈ 0.62·A·p 0 m FK Assuming that the stroke of the connecting rod 13 again corresponds to the effective percussion length, ie h _EK = I _eff , the following results:

and a mean acceleration of a = F m FK ≈ 0.62 · A · p 0 m FK

If the flying mass 14 moves from rest from the rearmost position to the striker 15, this will take approximately: τ = 2 l eff a ≈ 2 · l eff · m FK 0.62 · A · p 0

Typical numerical values are: r = 15 mm l eff = 35 mm m FK = 100g p 0 = 1 bar = 1E5 Pa

This results in a time constant of about 14 ms, which is sufficient for this Look up the flying pistons 14 completely.

A further permissible simplification possibility is to calculate the isentropic coefficient κ in Eq. (7) by the nearest integer fraction, ie: κ = 1.4≈ 3 2

The integral of Eq. (7) can be solved analytically in this case:

E denotes the complete elliptic integral of the second kind. Assuming that the connecting rod stroke again corresponds to the effective impact length, the result is:

The in Eq. (15) function E (x) is defined as follows:

Therein  denotes a general argument for the definition of the complete elliptic integral of the second kind (Eq. It is the integration variable to be integrated after. The argument of E (, m) is thus on the one hand the upper limit of the integral, on the other hand the module m. In our case:  = π / 2.

The function E (x) can be evolved around zero into a Taylor series. e ( x ) = π 2 - π · x 8th - 3π · x 2 128 - 5π · x 3 512 + O ( x 4 )

If only first-order terms are admissibly considered, then a reliable estimate for the average force results:

It can be concluded from this that the maximum overpressure that can be generated by the check valves is about 3/4 of the external pressure p ₀ , if it is assumed that the connecting rod length corresponds to the length l _{eff of} the percussion mechanism.

Tests have shown that the check valves are almost ideal can be accepted.

The model calculation presented so far, including the behavior of the Check valves will subsequently be tested using a realistic simulation Verified, in addition to the one for the performance of the Dismantling device significant improvement in terms of the required contact pressure by the operator and for a quick startup behavior Application comes.

A mining device of the type mentioned, in particular a drilling and / or Chisel hammer, the more user-friendly, the lower the contact pressure which the user has to apply in order for the device to Business interruption z. B. when settling of the ground, again starts up quickly and works stably. By generating a higher Pressure between the excitation piston 12 and the flying piston 14 when settling of the device becomes the contact force required for restart something increased.

For example, assuming a maximum overpressure of about 0.6 bar, resulting in an assumed diameter of the Guide tube 11 of d = 40 mm compressive forces of about 24 N, by the contact pressure to overcome.

To reduce these counterforces and a faster restart of the striking mechanism is, according to an advantageous embodiment provided, the excess air mass in the guide cylinder 11 to blow off an intermediate step. This variant The invention will be described below with reference to FIGS. 7A to 7C.

The with the check valve, z. B. the flap valve 20, equipped axially displaceable control sleeve 17 has in a certain axial Distance from the flap valve 20 at least one hole as Discharge port 32, but preferably one of the number of Schnauflöcher 18 corresponding plurality of discharge openings 32.

Fig. 7A shows the working position of the excavating device, in which the Schnauflöcher 18 are closed by the front portion of the control sleeve 17. When the excavator is lowered from the ground, the control sleeve 17 is displaced by the forwardly slipping stopper 15 about the path section Δx ₂ , so that the check valves, for example the flapper valve 20, are aligned with the blow holes 18, as shown in FIG. 7C. This corresponds to the pump-up position also shown in Fig. 2B, in which the flying mass 14 is stopped short term. When the operator starts a further dismantling process, an intermediate position of the striker 6 or of the control sleeve 17 is achieved when the device is attached, which is displaced by a smaller distance Δx ₁ relative to the working position shown in FIG. 7A, the so-called deflation position, in which the drain port (s) 32 are aligned with one or more of the blow holes 18. As a result, the excess air mass in the striking mechanism is quickly blown off, so that the impact mechanism begins to work again within a very short time.

The time-correlated partial diagrams (a) to (c) illustrated in FIG. 8 illustrate Simulation results with the impact mechanism according to Fig. 2 A / B were performed.

On the abscissa of the three superimposed diagrams is respectively the time in seconds (s) shown. On the ordinates of the three Diagrams are in the upper diagram (a) in its upper part diagram 33 the instantaneous position or the path-time profile of the excitation piston 12th and in the lower part of the diagram 34, the current position or the path-time course of the flying piston 14 reproduced.

The middle diagram (b) shows on the one hand in a solid line 35 the Total energy consumption and in the lower part the energy of the individual impacts, which are plotted as peaks 36.

The bottom part of the diagram (c) shows the time course of the in Schlagwerk existing air mass in a stop and start operation for a striking mechanism according to the invention.

The simulation results of FIG. 8 are to be interpreted as follows:

At t = 0.6 s, the pump-up or control sleeve 17 is activated, i. H. at the Settling of the device is shifted to the position shown in Fig. 2B. The Schlagwerk comes to a halt within two shots, which is fine can be seen from the partial diagram (b) of FIG. 8. At t = 1.2 s this will be Schlagwerk reactivated, it takes, as from the partial diagram (c) the Fig. 8 can be seen, about 400 ms, until the excess air in the percussion about the Schnaufloch or the Schnauflöcher 32 is degraded, and the percussion begins to work again.

The three graphs of Fig. 9 show a time-extended Part of the simulation results of Fig. 8. It can be seen from this clear that the flying-piston already after only two single strokes has reached a rest position (partial diagram (a)). The exciter piston 12 continues to run and changes accordingly in Schlagwerk existing Pulsating air mass, which is good from the partial diagrams (c) the Fig. 8 and 9 can be seen.

The graphic representation of FIG. 10 corresponds to a time-extended detailed representation the graph of FIG. 8 from the time t = 1.1 s. Out the partial diagrams (b) and (c) of FIG. 10 can be read particularly well, that without additional deflation, as illustrated by FIG. 10, the percussion after about 400 ms its full impact performance has reached. The excess air gets over the or the Schnauflöcher although in a tolerable for practice period, but with a noticeable time delay reduced.

The FiG. FIGS. 11 and 12 show the already explained FIGS. 8 and 10, respectively Graphics or diagrams for a striking mechanism with a Pump-up or control sleeve 17 shown in FIG. 7 with additional (additional) Discharge opening (discharge openings) 32.

According to FIG. 8, FIG. 11 shows an overview of a stop and starting process of a striking mechanism by means of an inventive Pump-up or control sleeve 17, the FIG. 7 additional discharge openings 32 has. Again, at t = 0.6 s, the control sleeve 17 in brought the position shown in Fig. 7C. The percussion comes inside from two beats to a halt. At t = 1.2 s the percussion becomes activated again. Unlike in FIG. 8 or FIG. 10, FIG. 11 is shown in FIG. 11 and 12 well obvious that the percussion is almost immediately too hammering begins, which in both Figs. 11 and 12 the partial diagrams (b) and (c) good. This favorable start-up behavior of the impact mechanism becomes due to the additional blowing over the discharge port 32nd reached. This excess air is by a short venting of the Schlagwerks quickly dismantled.

Another basic embodiment of the invention below Using a pump with accumulator is described below Figs. 13 and 14 described.

In this illustrated by two embodiments variant the invention uses the electropneumatic hammer mechanism itself to fill an intermediate pressure accumulator 45, which via a preferably controllable valve 46 in the percussion, in particular in the air spring 19 is emptied as soon as the contact force decreases or the mining equipment lifted off the ground.

FIG. 13 shows an embodiment with one of the exciter piston drive operated additional reciprocating pump 40, which via check valves 41, 42 is connected to the intermediate pressure accumulator 45. The suction sides the reciprocating pump 40 also have check valves 43, 44 on. At the accumulator 45, a pressure relief valve 47 may be provided his.

As the embodiment of Fig. 14 shows, it is also possible that Volume 50 of the eccentric 42 for the exciter piston 12 directly as Pump volume to use, with the crankcase as the pump housing 51 serves. The check valves 53 and 54 correspond in their Function of the check valves 41, 42 and 43, 44 in FIG. 13.

The advantage of this embodiment of the invention over the Variant with pump-up or control sleeve is that the maximum Pressure in percussion not by the dimensions of the flying piston path and / or the Exzenterhubs are given and thus not on the ambient pressure, So about 1 bar, are limited. It can be clear produce higher pressures, which in principle an even more reliable and faster shutdown of the dismantling device when lifting off the ground allows. It is also advantageous that the pressure at the time of switching off already available.

A third embodiment of the invention is based on the use fast switching valves with a sub-variant of a dynamic quickly sliding sliding sleeve. Two embodiments are shown in Figs. 15 and 16.

In the embodiment of Fig. 15, the function of a check valve compared with the embodiments described with reference to FIGS. 1 to 12 replaced by a fast switching valve 60, the one can be magnetically actuated 2/2-way valve. In the drums To generate an overpressure, the valve 60 is closed as soon as the Exciter piston 12 changes its direction of movement at the rear dead center. The air is compressed and generated during the advance of the exciter piston 12 an overpressure. The valve 60 is then reopened each time shortly after the exciter piston 12 the front dead center or reversal point has reached.

This embodiment of the invention has the advantage that after the Turn off the percussion before the next start by a short Opening the valve 60, the pressure equalization can be made immediately. However, the requirements for the valve 60 are relatively high; there are Switching frequencies of more than 50 Hz necessary. Also the nominal sizes a feedthrough bore on the guide tube 11 (not shown in Fig. 15) or on the valve itself, need for a quick gas exchange be sized relatively large, z. B. diameters of 3 to 4 mm are required. For this embodiment are mainly electrically actuated slide valves or rotary valves in question.

An embodiment of the invention in which a control sleeve itself is used directly as a slide valve is shown in Fig. 16. A Control sleeve 61, which closes the Schnauflöcher 18 in an end position and releases in a second end position, forming at the same time a bobbin and forms the anchor of a voice coil actuator 62, which is placed centrally around the guide tube 11.

Claims (22)

Method for improving the turn-off behavior of an electropneumatic removal device, in particular a rotary and / or chisel hammer, in which a fly piston (14) accelerated via an air spring (19) by an electrically driven excitation piston (12) acts on a removal tool within a guide tube (11), characterized in that the pressure between the flying piston and the exciting piston is increased to reduce the lookup of the flying piston when lifting the mining equipment from the machined surface. Dredging device with electropneumatic hammer mechanism, in particular drill and / or chisel hammer whose percussion an electrically within a guide tube (11) driving back and forth driven exciter piston (12) which accelerates a flying piston (14) via a compressed air spring of this (19) which in turn strikes a knock-down tool held in a tool holder (9), characterized by a valve device (30) which can be activated by the dismantling of the dismantling device, by means of which the pressure acting between the motive and motive pistons is increased in the impact mechanism. Dismantling device according to claim 2, characterized in that the valve device has at least one non-return valve (20, 28), by means of which the negative pressure arising during the return stroke of the excitation piston between the latter and the flying piston during lifting of the dismantling device to a higher pressure, preferably approximately ambient pressure, is raised. Dismantling device according to claim 2, characterized in that the guide tube in the region of the air spring has at least one bore (puff hole 18), and that the check valve is displaceable relative to the guide tube and arranged so that when lifting the excavation device from the ground by an adjusting device (16 ) is alignable to this bore (18). Dredging device according to claim 3, characterized in that the check valve is integrated in a guide tube surrounding the control sleeve (17) which is displaceable by the adjusting device. Dredging device according to claim 3 or 4, wherein the air piston driven via the air spring striking acts on a tool holder associated with the beatpiece (15), characterized in that the adjusting device for the check valve is actuated by the striker. Dredging device according to claim 6 in conjunction with claim 5, characterized in that the control sleeve is axially displaceable by the adjusting device relative to the guide tube. Dredging device according to claim 6 in conjunction with claim 5, characterized in that the control sleeve is rotatable by the adjusting device relative to the guide tube. Dredging device according to at least one of the preceding claims 3 to 8, characterized in that the check valve is a flapper valve (20). Dredging device according to claim 5, characterized in that the check valve is in the peripheral wall of the control sleeve (17) integrated flap valve (20). Dredging apparatus according to claim 10, characterized in that the flap valve (20) is formed by a cantilevered transversely to a passageway extending leaf spring (22). Dredging device according to claim 5, characterized in that the check valve is in the control sleeve (17) integrated ball valve (28). Dredging device according to claim 12, characterized in that the bias of the ball valve via an on a compression spring (29) acting adjusting screw (31) is adjustable. Dredging apparatus according to claim 2, characterized by an accumulator device (45) through which the pressure in the impact mechanism is increased upon activation of the valve means. Dredging apparatus according to claim 14, characterized in that the pressure accumulator is precharged by a pump (40; 50) actuated by means of the exciter piston drive. Dredging device according to claim 15, characterized in that the pump is operated by a connecting rod drive of the exciter piston reciprocating pump (40). Dredging device according to claim 15, characterized in that the pump is actuated by the drive of the exciter piston eccentric pump. Dredging device according to claim 2, characterized in that the valve device is an electromagnetically operable valve. Dismantling device according to claim 18, characterized in that the valve is formed by an electromagnetically actuated control sleeve (61) which closes in a switching position at least one guide tube passing through the puff hole to the air spring and releases in a different switching position. Dredging device according to claim 19, characterized in that the control sleeve is axially displaceable by a voice coil actuator. Dredging device according to claim 20, characterized in that the control sleeve forms the displaceable core of the voice coil actuator. Dredging apparatus according to one of the preceding Claims 2 to 20, characterized by at least one discharge opening (32) passing through the control sleeve (17; 61) for rapid reduction of overpressure in the percussion mechanism during picking / resuming of the hammer or chisel operation.

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