EP0461565B1 - Method and device for the determination of characteristic features of an impact motor - Google Patents

Abstract

In order to determine characteristic quantities by means of which the operational performance of an impact machine can be influenced, it is proposed to determine the impact velocity of the impact piston (26) shortly before, and its return velocity shortly after, the impact, by using a relative movement corresponding to the impact piston movement to trigger in each case a plurality of time marks (t1, t2 or t3, t4) which are assigned to a working stroke section or return stroke section ( DELTA s) and succeed one another at a time interval, and by determining the time intervals between the succeeding time marks of the working stroke and the return stroke. The values of the time intervals between the relevant time marks are used continuously to determine and render capable of evaluation at least one of the further characteristic quantities of number of impacts, impact energy, impact power, reflection energy, reflection factor, position of the power impact plane and temporal variation in the position of the impact plane. <IMAGE>

Description

The invention relates to a method for determining characteristic parameters for the purpose of influencing the operating behavior of an impact mechanism with a percussion piston, which alternately executes a working stroke in the direction of impact and a return stroke when acted upon by a fluid drive means. The invention also relates to a device suitable for carrying out the method on a percussion mechanism with a cylinder and a percussion piston guided therein, which alternately under the action of a fluid drive means - which can alternately be connected to a pressure source and to a pressure-free return via a control performs a working stroke in the direction of impact and a return stroke.

It has already been proposed to adapt the operating behavior of impact mechanisms to the material to be processed by mutually coordinating the individual impact energy transmitted by the impact piston and its impact number. This is done by changing the percussion piston stroke and / or the pressure of the incompressible drive means by hand or remotely (DE-PS 17 03 061 or DE-A1-26 58 455).

Furthermore, methods and control devices are known which control the processing material convert the conditional disturbance factors into control variables to adapt the operating behavior of a hammer mechanism or a rotary hammer. DE-A1-35 18 370 describes a method for optimizing percussion drilling, in which the voltage wave generated on the boring bar due to a blow is measured and the drilling device is regulated on the basis of the measured voltage wave. The voltage wave subsides faster if the force pushing the drilling device into the machining material increases.
According to the teaching of EP-A1-02 14 064, the dwell time of the percussion piston in the vicinity of its theoretical striking position is measured with each impact process and, depending on this measured value, acts on the regulating device for the impact parameters (impact speed, impact frequency of the impact piston). The measurement signal is derived hydraulically from the dwell time of the percussion piston; However, this is not only dependent on the properties of the machining material, so that an optimal adaptation of the operating behavior of the striking mechanism requires the consideration of further influencing variables.
Also in the subject of EP-A1-02 56 955, the impact parameters (hydraulic pressure, percussion piston stroke) are influenced hydraulically as a function of the pressure fluctuations which occur in the chambers formed by the percussion piston as a result of the rebound of the percussion piston.

The invention is based on the object of specifying a method and a device for determining characteristic parameters, which allow the operating behavior of a striking mechanism to be influenced with justifiable technical outlay, taking into account a larger number of parameters, if necessary, via a controller (possibly also by hand) and / or by regulating at least a portion of the workflow.

The object is achieved by a method with the features of claim 1. The basic idea of the invention is then to determine the different characteristic parameters which are characteristic of the operating behavior of a striking mechanism (in particular impact energy, impact performance, reflection energy, reflection factor, position of the impact level and temporal change in the position of the impact level) on the approximate determination of the impact - and return flight speed of the percussion piston, that is to say on the working stroke speed of the percussion piston shortly before and its return stroke speed shortly after the impact. By means of a relative movement corresponding to the percussion piston movement (for example between the percussion piston and the cylinder itself enclosing it), several time marks associated with a working stroke or return stroke path section are triggered during each working cycle, and the time intervals between the successive time stamps of the working stroke and the return stroke are triggered determined. The method can, for example, be designed in such a way that four time stamps are triggered during each working cycle, namely two during the working stroke shortly before and two during the return stroke shortly after the impact piston strikes. Since the stroke path sections which normally correspond in terms of their size are known (and usually have a constant size) through which the percussion piston has traveled in the associated time span during the working and return strokes, the size corresponds to the time intervals between the successive time stamps of the working stroke. and the return stroke with Sufficient approximation of the size of the impact speed and the return flight speed: Experience has shown that the speed of the percussion piston changes at most to a negligible extent during the working and return stroke near the point of impact.
From the determined size of the impingement and / or return flight speed, further characteristic parameters can be continuously determined (for example by means of a computer), such as the impact energy, the impact power, the reflection energy, the reflection factor and the position of the impact plane of the impact piston.
The time stamps can be generated in such a way that they either represent a short, pulse-like signal or are part of a longer-lasting signal, that is to say form its start and end area. If only a single signal is generated during a given working stroke or return stroke section, a statement can be made from its duration alone or by comparison with the duration of the associated other signal of each working cycle as to how high the working stroke speed is shortly before or Return stroke speed is shortly after the impact and which size corresponds approximately to the impact or return flight speed.
In the simplest case, the time interval between the first and the second time stamp of the working stroke and the first and second time stamp of the return stroke is approximately proportional to the size of the impact or return flight speed (cf. claim 2). From this size ratio, conclusions can be drawn about the working conditions of the striking mechanism, with the result that its operating behavior - for example changes that are becoming apparent mentioned size ratio - can be adjusted by hand or via a scheme.
If necessary, the method can also be carried out in such a way that the time stamps are a component of signals which overlap in time and the time intervals between the time stamps which form the start and end areas of the signals are determined during each working cycle.

The time stamps are preferably triggered by a relative movement between at least one sensor head and at least one marking scanned by it (claim 3); the at least one sensor head and the at least one marking are therefore at least indirectly part of either the percussion piston or the cylinder.
The time stamps can be triggered by scanning two markings each during the working stroke and the return stroke (claim 4).

Within the scope of the invention, however, the method can also be designed in such a way that a marking is scanned twice or a marking is scanned during the working stroke and the return stroke; this presupposes that the at least one marking interacts with a sensor head or with two sensor heads.
The timestamps can be generated in particular by optically scanning the percussion piston or by inductively acquiring the timestamps. Another advantageous embodiment of the method is to generate the time stamps hydraulically by the fact that the aforementioned relative movement (for example between the percussion piston and the cylinder) causes a change in pressure signal which is detected by at least one sensor head in the form of a pressure sensor.

The information determined using the characteristic parameters can be used by an operator to influence the operating behavior of the striking mechanism directly by hand or by adjusting a controller characteristic curve by hand. However, it is also possible to use the characteristic parameters at least partially as input variables for controlling the striking mechanism; this can be done by directly intervening in the regulation of the striking mechanism and / or in the regulation of the hydraulic unit, which forms the energy source for the operation of the striking mechanism.
The time interval between a time stamp and the corresponding time stamp of the subsequent work or return stroke is synonymous with the period of the work cycle; their reciprocal value corresponds to the number of strokes performed by the percussion piston in the time unit.

By continuously determining the characteristic parameters derived from the number of blows and the speed values of the striking piston, the operator of the striking mechanism receives important information about the material properties, the wear of the chisel tip driven by the striking piston, the guidance of the striking mechanism, the position of the impact level, the wear of the accessories determining the impact level and the performance of the striking mechanism:

Material quality

The aim of the use of striking mechanisms is to extract, crush or destroy materials which, due to their hardness and / or toughness, cannot be processed or cannot be processed economically by other methods.
While the impact energy E₀ required for the destruction increases with increasing material hardness the impact energy should be reduced and the number of blows z should be increased when processing softer materials.
The display of the instantaneous size, including the impact performance N, enables adaptation to different working conditions by changing the impact energy and number of impacts. The size of the reflection factor R can provide clues about the nature of the processing material: the hardness also increases the size of the reflection factor. The continuously determined value of the characteristic parameter R thus represents an important assessment basis for influencing the operating behavior of the striking mechanism (by changing the parameters E₀ and z) in the sense of an advantageous adaptation.

Chisel tip wear

“Chisel tip” is to be understood here as the initial shape of the chisel end, which can be designed differently and undergoes a change due to wear.
The size of the reflection factor R is also influenced by the nature of the chisel tip: if the material properties remain the same over a longer period of time, a slow change in the size of the reflection factor indicates a change in the initial shape, ie wear of the chisel tip.

Leading the striking mechanism

When processing hard material, a dust cushion forms under the chisel tip, which partially absorbs the impact energy. The operator can react to the rapid change in the size of the reflection factor in the course of a stroke by displacing the striking mechanism. If the size of the reflection factor changes rapidly, it can disadvantageous development - for example via a computer - can also be made recognizable in the form of a warning signal.

Location of the service level

The position of the impact plane, in which the percussion piston strikes the chisel, can be determined with respect to the cylinder by a dimension a₀. The invention allows the position of the impact level to be determined and displayed continuously. If the parameter Δa (at a = a₀) has the value zero, the functioning of the striking mechanism is to be regarded as normal. The rapid increase in the value a - and thus the rapid decrease in the parameter Δa - indicates strong tension between the striking mechanism and the chisel, which results in a shifting of the striking mechanism with respect to the chisel. This unfavorable operating behavior can be counteracted by a suitable displacement in such a way that the chisel returns to its target position and the percussion piston can thus transmit its target impact energy.

wear

über eine längere Zeitspanne läßt auf einen Verschleiß an der Schlagfläche des Schlagkolbens und/oder des Meißels im Schlagwerks schließen.A slow change in value $\text{Δa = a₀ - a}$

Over a longer period of time, wear on the striking surface of the striking piston and / or the chisel in the striking mechanism can be assumed.

Performance control of the striking mechanism

The display of the striking power N of the striking mechanism shows whether it is still capable of working. By comparing the impact power and the hydraulic power consumed, a statement can be made as to whether the underperformance of the impact mechanism is due to this or the hydraulic energy source.

The manner in which the characteristic parameters can be obtained will be explained in detail later using the drawing. They can be entered as the actual value in at least one controller and thus at least partially relieve the operator. The invention allows the evaluation, the computer and the at least one controller to be arranged, for example, in the cabin of the carrier device and the characteristic curve of the controller to be adjustable in order to adapt the operating behavior of the striking mechanism to the material to be processed by changing the impact energy and the stroke rate. This is advantageous in that the cleavage of the processing material depends in a complex manner on several factors which cannot be optimally determined by a single controller characteristic. Programs can also be specified via the computer which, for example, control the start of the striking mechanism and / or at least indicate or even prevent a useless or harmful mode of operation of the striking mechanism.

The object is further achieved by a device with the features of claim 5. This is equipped with a sensor unit (with at least one sensor head) which, in cooperation with at least one marking arranged on the percussion piston, triggers several time marks shortly before and shortly after the impact of the percussion piston, based on which the time span required for the associated working stroke or return stroke section can be determined by means of an evaluation. This is followed by a computer with which, based on the determined time intervals between the time stamps of the work and return strokes, taking into account the size of the associated stroke section, in addition to the size of the impact and return flight speeds, at least one of the characteristic parameters. Impact number, impact energy, impact performance, reflection energy, reflection factor, position of the impact level and temporal change in the position of the impact level - continuously determined.
In the simplest embodiment, the sensor unit and the at least one marking scanned by it are designed and assigned to one another in such a way that a total of four time stamps are generated during the working and return strokes. From the time interval between the two successive time stamps of the working and return strokes, the size of the impact and return flight speeds of the percussion piston is approximated without any significant increase in time.

One embodiment of the device, with which two time marks in succession can be generated in the course of the working and return strokes, has a sensor unit with a sensor head effective in the direction of the cylinder bore, past which two markings can be moved back and forth , which follow each other in the direction of movement of the percussion piston at a distance (claim 6); the markings themselves have only a relatively small extent in the direction of movement of the percussion piston.
Each marking can consist in particular of an annular groove arranged transversely to the percussion piston longitudinal axis or also of a peripheral edge of the percussion piston. The at least one sensor head of the sensor unit is preferably arranged in the cylinder or is part of the cylinder.

The time marks belonging together in pairs can also be generated by means of a sensor unit with two sensor heads which are arranged at a distance from one another in the direction of movement of the percussion piston (claim 7).

Provided that the rear end section of the percussion piston is designed as a hollow piston section, the device can also be designed in such a way that a retaining bolt, which is aligned parallel to the percussion piston longitudinal axis and which is fastened to the cylinder and projects with at least one, projects into the hollow piston section Sensor head equipped sensor unit carries; the at least one associated marking is attached to the bore wall of the hollow piston section (claim 8). The embodiment in question thus has a sensor unit which is only indirectly (namely via the retaining bolt) part of the cylinder.

One embodiment of the device for generating a longer-lasting working stroke and return stroke signal - the beginning and end of which are each formed by a time stamp - has only one sensor head, past which there is a marking with a size of the lifting section in the direction of movement of the percussion piston corresponding longitudinal extension can be moved back and forth; the sensor head or the marking is arranged in such a way and its length in the direction of movement of the percussion piston is dimensioned such that the marking lies outside the effective range of the sensor head before the percussion piston carrying out the working stroke or the return stroke reaches the impact point or the upper reversal point has (claim 9). The time interval between the two successive time stamps of the working and return strokes corresponds to the time span during which the signal is present.

The more general idea on which the claim 9 is based is one of the two devices interacting when the piston movement is sensed - namely the sensor head or the Marking - to be equipped with a greater longitudinal extension in the direction of the piston movement; the result of this is that only one signal is present on a stroke section specified by the longitudinal extent during the working and return strokes over a longer period of time, the start and end areas of which are each formed by two time stamps.

However, the sensor unit can also have two sensor heads, past which a mark can be moved back and forth in the direction of movement of the percussion piston. The marking has a length that is at least larger than the mutual distance between the sensor heads in the direction of movement of the percussion piston by the percussion piston path between the end point of the working stroke section or the starting point of the return stroke section and the theoretical point of impact. As long as the percussion piston hits the material to be processed at the theoretical point of impact, this results in the generation of two signals, the duration of which is determined by the time interval between the first time stamp of the working stroke and the last time stamp of the return stroke or between the second time stamp of the working stroke and the first Return stroke timestamp is set; the first-mentioned signal is applied to the sensor head, which first interacts with the marking due to the movement of the percussion piston in the direction of impact.
If the percussion piston hits the material to be processed later than is theoretically intended (i.e. there is a shift in the impact plane), this deviation results in a changed time course of the signals applied to the sensor heads. If the signal at the first sensor head in the direction of impact is omitted while the signal is still present at the second sensor head, this is an indication that the position of the impact plane has undergone a change.

A shift of the impact level in the direction of a larger percussion piston stroke leads to the signal in question disappearing immediately before the impact when the second signal is present and being present again immediately after the impact. The time interval of interest in this connection for determining the speed of impact and return flight corresponds to the time interval between the first time stamp or between the last time stamp of the two signals.

Each sensor head can in particular consist of supply and return light fibers - whose end sections arranged in a plane transverse to the longitudinal axis of the percussion piston are connected to the cylinder space and which are connected to the evaluation - or can be designed as pressure sensors. The latter embodiment is such that any relative movement between the at least one pressure sensor and the at least one marking is converted into a short-term or a relatively longer-lasting pressure change and thereby made evaluable.
The subject matter of the invention can also have a sensor unit which operates on the basis of the electrical discharge. Each sensor head and each marking are designed as electrodes, between which an electrical discharge takes place on the basis of the greatest possible mutual approximation, each sensor head being connected to a voltage source acting on it (claim 11). The electrical discharge occurs between electrodes that are attached to the percussion piston or are part of the cylinder. In contrast to the electrode forming the sensor head, the percussion piston and the cylinder or the component of the cylinder receiving the sensor head are electrically at ground potential. The discharge current triggered during the movement of the percussion piston generates on one Resistance a voltage pulse evaluable in the sense of the invention.

The device for determining the characteristic parameters can also be designed according to claim 12. In this case, each sensor head is constructed as a field plate transmitter working according to the magnetoresistive principle with at least one semiconductor resistance element, the resistance of which changes with the passing of the at least one marking. In this embodiment, use is made of the knowledge that the electrical resistance of certain semiconductor materials changes considerably if the magnetic field flowing through the semiconductor material experiences a change. This can be caused in a simple manner by an annular groove which is moved relative to the magnetic field (preferably generated by means of a permanent magnet). The change in resistance in the semiconductor resistance element can be identified or evaluated in the form of a change in voltage or a voltage pulse.

Fig. 1

aufgetragen in einem Weg-Zeit-Diagramm die Bewegung des Schlagkolbens,

Fig. 2 a, b

in gegenüber Fig. 1 vergrößerter Darstellung einen Ausschnitt des Weg-Zeit-Diagramms im Bereich des Kolben-Aufschlagpunktes bzw. ein Diagramm mit den zugehörigen, über der Zeit aufgetragenen Zeitmarken

Fig. 3

ein Schemabild, aus dem der Verlauf der Information zwischen dem Schlagwerk und den zugehörigen Zusatzeinrichtungen ersichtlich ist,

Fig. 4

stark schematisiert eine Gesamtansicht des Schlagwerks nebst Trägergerät,

Fig. 5

als Schemabild einen Schnitt durch ein Schlagwerk mit Sensoreinheit und Steuerung,

Fig. 6a

einen gegenüber Fig. 5 vergrößerten Teilausschnitt des Schlagwerks im Bereich der Sensoreinheit,

Fig. 6b, c

in vergrößertem Maßstab eine in Fig. 6a mit B bzw. C bezeichnete Einzelheit,

Fig. 7

stark schematisiert eine Sensoreinheit mit einem Sensorkopf, dem zwei am Schlagkolben angeordnete Ringnuten als Markierungen zugeordnet sind,

Fig. 8

stark schematisiert eine mit zwei Sensorköpfen ausgestattete Sensoreinheit, der als Markierung eine Umlaufkante des Schlagkolbens zugeordnet ist,

Fig. 9, 10

in vergrößertem Maßstab einen Teilausschnitt des Schlagwerks in der Ausführungsform gemäß Fig. 6a bzw. 7,

Fig. 11a, b

einen Ausschnitt des Weg-Zeit-Diagramms bzw. ein Diagramm mit den über der Zeit aufgetragenen Zeitmarken, die sich bei der Ausführungsform gemäß Fig. 9 und 10 ergeben,

Fig. 12

in vergrößertem Maßstab einen Teilausschnitt einer Ausführungsform, die derjenigen gemäß Fig. 6a ähnlich ist mit der Maßgabe, daß eine Ringnut 40 von zwei Sensorköpfen 38a und 38b abgetastet wird,

Fig. 13

in vergrößertem Maßstab einen Teilausschnitt einer Ausführungsform, die derjenigen gemäß Fig. 7 ähnlich ist mit der Maßgabe, daß lediglich eine Ringnut von zwei mit Abstand voneinander angeordneten Sensorköpfen abgetastet wird,

Fig. 14a bis c

einen Ausschnitt des Weg-Zeit-Diagramms bzw. Diagramme mit den über der Zeit aufgetragenen Zeitmarken, die bei der Ausführungsform gemäß Fig. 12 und 13 von dem - in Schlagrichtung des Schlagkolbens gesehen - zweiten bzw. ersten Sensorkopf erzeugt werden,

Fig. 15, 16

in vergrößertem Maßstab einen Teilausschnitt einer Ausführungsform, die derjenigen gemaß Fig. 6a bzw. 7 ähnlich ist mit der Maßgabe, daß ein einziger Sensorkopf eine Ringnut mit größerer Längserstreckung Δs in Bewegungsrichtung des Schlagkolbens abtastet,

Fig. 17a, b

einen Ausschnitt des Weg-Zeit-Diagramms bzw. ein Diagramm mit den Signalen und Zeitmarken, welche durch die Ausführungsform gemäß Fig. 15 bzw. 16 erzeugt werden,

Fig. 18, 19

in vergrößertem Maßstab einen Teilausschnitt einer Ausführungsform, die derjenigen gemäß Fig. 6a bzw. 7 ähnlich ist mit der Maßgabe, daß zwei mit Abstand Δs voneinander angeordnete Sensorköpfe eine Ringnut mit größerer Längserstreckung abtasten,

Fig. 20a bis c

einen Ausschnitt des Weg-Zeit-Diagramms bzw. Diagramme mit den über der Zeit aufgetragenen, von den Ausführungsformen gemäß Fig. 18 bzw. 19 erzeugten Signalen und Zeitmarken für den Fall, daß der Aufschlagpunkt des Schlagkolbens in der theoretisch angenommenen Aufschlagebene liegt,

Fig. 21, 22

in vergrößertem Maßstab einen Teilausschnitt einer Ausführungsform, die derjenigen gemäß Fig. 18 bzw. 19 ähnlich ist mit der Maßgabe, daß der Aufschlagpunkt des Schlagkolbens von der theoretisch vorgegebenen Aufschlagebene abweicht,

Fig. 23a bis c

einen Ausschnitt des Weg-Zeit-Diagramms bzw. Diagramme mit den über der Zeit aufgetragenen Signalen und Zeitmarken, die von den Ausführungsformen gemäß Fig. 21 bzw. 22 erzeugt werden,

Fig. 24a

einen Teilausschnitt des Schlagwerks nebst Sensoreinheit mit einem Sensorkopf, welcher auf der Grundlage der elektrischen Entladung arbeitet,

Fig. 24b

ein elektrisches Schaltschema zur Ausführungsform gemäß Fig. 24a,

Fig. 25a

schematisiert einen Teilausschnitt eines Schlagwerks im Bereich einer Sensoreinheit, welche nach dem magnetoresistiven Prinzip arbeitet, und

Fig. 25b

ein elektrisches Schaltschema zu der Ausführungsform gemäß Fig. 25a.

The invention is explained below with reference to the drawing.
Show it:

Fig. 1

plotted the movement of the percussion piston in a path-time diagram,

2 a, b

in an enlarged representation compared to FIG. 1, a section of the path-time diagram in the area of the piston impact point or a diagram with the associated time stamps plotted over time

Fig. 3

a schematic image from which the course of the information between the striking mechanism and the associated additional devices can be seen,

Fig. 4

highly schematic an overall view of the striking mechanism and carrier device,

Fig. 5

as a schematic image a section through a hammer mechanism with sensor unit and control,

Fig. 6a

5 shows an enlarged partial section of the striking mechanism in the area of the sensor unit,

Fig. 6b, c

on an enlarged scale a detail designated B or C in FIG. 6a,

Fig. 7

a sensor unit with a sensor head, to which two ring grooves arranged on the percussion piston are assigned as markings,

Fig. 8

a sensor unit equipped with two sensor heads, to which a peripheral edge of the percussion piston is assigned as a marking, is highly schematized,

9, 10

6a or 7, on a larger scale, a partial section of the striking mechanism,

11a, b

a section of the path-time diagram or a diagram with the time marks plotted over time, which result in the embodiment according to FIGS. 9 and 10,

Fig. 12

on an enlarged scale, a partial section of an embodiment which is similar to that according to FIG. 6a with the proviso that an annular groove 40 is scanned by two sensor heads 38a and 38b,

Fig. 13

7 on an enlarged scale, a partial section of an embodiment which is similar to that according to FIG. 7 with the proviso that only an annular groove is scanned by two sensor heads arranged at a distance from one another,

14a to c

a section of the path-time diagram or diagrams with the time marks plotted over time, which at 12 and 13 are produced by the second or first sensor head, as seen in the direction of impact of the percussion piston,

15, 16

on an enlarged scale, a partial section of an embodiment which is similar to that according to FIGS. 6a and 7, with the proviso that a single sensor head scans an annular groove with a larger longitudinal extension Δs in the direction of movement of the percussion piston,

17a, b

a section of the path-time diagram or a diagram with the signals and time marks, which are generated by the embodiment according to FIGS. 15 and 16,

18, 19

6a and 7, with the proviso that two sensor heads arranged at a distance Δs from one another scan an annular groove with a greater longitudinal extent,

20a to c

18 shows a section of the path-time diagram or diagrams with the signals and time stamps plotted over time generated by the embodiments according to FIGS. 18 and 19 in the event that the impact point of the percussion piston lies in the theoretically assumed impact plane,

21, 22

on an enlarged scale, a partial section of an embodiment, 18 or 19 is similar with the proviso that the impact point of the percussion piston deviates from the theoretically predetermined impact level,

23a to c

a section of the path-time diagram or diagrams with the signals and time marks plotted over time, which are generated by the embodiments according to FIGS. 21 and 22,

Fig. 24a

a partial section of the striking mechanism and sensor unit with a sensor head, which works on the basis of the electrical discharge,

Fig. 24b

an electrical circuit diagram for the embodiment of FIG. 24a,

Fig. 25a

schematically shows a partial section of a striking mechanism in the area of a sensor unit which works according to the magnetoresistive principle, and

Fig. 25b

an electrical circuit diagram for the embodiment of FIG. 25a.

From Fig. 1, the movement of the percussion piston during the working stroke in the direction of impact, ie between the top dead center s _O and the impact point s _A , and during the return stroke, ie between the impact point and the top dead center, can be seen. The lines describing the working stroke and the return stroke are approximately rectilinear in the vicinity of the point of impact.

bzw. $\text{Δt₃ = t₄ - t₃}$

ermittelt wird (vgl. dazu Fig. 2a und 2b).
Weiterhin wird der Zeitabstand T (entsprechend der Periodendauer) zwischen einer Zeitmarke (beispielsweise t_1.n) und der entsprechenden Zeitmarke des nachfolgenden Arbeits- bzw. Rückhubes (beispielsweise t_1.n+1) gemessen, aus dessen Kehrwert sich die Schlagzahl z des Schlagwerks bestimmen läßt (z = 1/T).The movement of the percussion piston shortly before and just after its impact point s _A - after each travel a predetermined stroke section (s₁ - s₂) - triggered two time stamps t₁, t₂ and t₃, t₄, the time interval $\text{Δt₁ = t₂ - t₁}$

respectively. $\text{Δt₃ = t₄ - t₃}$

is determined (cf. FIGS. 2a and 2b).
Furthermore, the time interval T (corresponding to the period) between a time stamp (for example t _1.n ) and the corresponding time stamp of the subsequent working or return stroke (for example t _{1.n + 1} ) is measured, from the reciprocal of which the beat number z of Percussion mechanism can be determined (z = 1 / T).

lassen sich die weiteren charakteristischen Kenngrößen des Schlagwerks wie folgt berechnen:Using the time interval equations $${\text{t₃ - t₂ = Δt₂; t}}_{\text{A}}{\text{- t₂ = t}}_{\text{x}}{\text{; t₃ - t}}_{\text{A}}{\text{= t}}_{\text{Y}}$$

the other characteristic parameters of the striking mechanism can be calculated as follows:

Impact speed of the percussion piston:

${\text{V}}_{\text{A}}\text{≈ Δs / Δt₁ = (s₂ - s₁) / (t₂ - t₁)}$

Return flight speed of the percussion piston:

${\text{v}}_{\text{R}}\text{≈ Δs / Δt₃ = (s₂ - s₁) / (t₄ - t₃)}$

Impact energy:

${\text{E}}_{\text{O}}{\text{= mxv}}_{\text{A}}\text{² / 2 = C / (t₂ - t₁) ²}$

Impact performance:

$\text{N = E xz}$

Reflection energy:

${\text{E}}_{\text{R}}{\text{= <figure-callout id="2" label="mxv R" filenames="imgf0003.png,imgf0004.png" state="{{state}}">mxv </figure-callout>}}_{\text{R}}\text{² / 2 = C / (t₄ - t₃) ²}$

Reflection factor:

${\text{R = E}}_{\text{R}}\text{/ E₀ = ((t₂ - t₁) / (t₄ - t₃)) ²}$

Location of the service level:

The distance between the impact plane at s = s _A and the position of the percussion piston at s = s₂ is denoted by a₀; this results in s _A - s₂ = a₀.
If the percussion piston does not hit the chisel at the point s = s _A , but at any point, the deviation results from this: $$\text{Δa = a₀ +/- a = a₀ +/- Δs x Δt₂ / (Δt₁ + Δt₃)}$$

${\text{v}}_{\text{R}}{\text{≈Δs/Δt₃≈(Δs + a)/(Δt₃ + t}}_{\text{y}}\text{)}$

${\text{t}}_{\text{x}}{\text{+ t}}_{\text{y}}{\text{= Δt₂ (d.h. t}}_{\text{x}}{\text{= Δt₂ - t}}_{\text{y}}\text{)}$

$\text{a = Δs x Δt₂/(Δt₁ + Δt₃)}$

The size a can be calculated using the equations:
${\text{v}}_{\text{A}}{\text{≈Δs / Δt₁≈ (Δs + a) / (Δt₁ + t}}_{\text{x}}\text{)}$

${\text{v}}_{\text{R}}{\text{≈Δs / Δt₃≈ (Δs + a) / (Δt₃ + t}}_{\text{y}}\text{)}$

${\text{t}}_{\text{x}}{\text{+ t}}_{\text{y}}{\text{= Δt₂ (ie t}}_{\text{x}}{\text{= Δt₂ - t}}_{\text{y}}\text{)}$

$\text{a = Δs x Δt₂ / (Δt₁ + Δt₃)}$

Under the aforementioned conditions, all of the characteristic parameters of the striking mechanism can be determined if the time interval values in question are known.
The size m (corresponding to the mass of the percussion piston) represents a constructive predetermined constant as well as the distance value Δs, to which the time stamps t₁, t₂ or t₃, t₄ are assigned.
These are - triggered by the movement of the percussion piston provided with at least one marking - generated by a sensor unit to be described.

The basic structure and the mode of operation of the subject matter of the invention can be seen in FIG. 3. A hydraulic unit 1 as an energy source generates the hydraulic power, which is converted into impact power in the striking mechanism 2 in that a chisel 3 driven by the striking mechanism acts on the material 4 to be processed in a sequence of individual impacts with the energy (impact energy) E _O. Depending on the operating conditions, part of the impact energy is transmitted back as reflection energy E _R from the material 4 via the chisel 3 to the striking mechanism 2.
The position of the striking mechanism 2 with respect to the material 4 can be changed by means of a guide unit 5 and adapted to the operating conditions.

The movement of the percussion piston 26 cooperating with the chisel 3, for example shown in FIG. 5, during the working stroke (ie in the direction of impact) triggers shortly before and during the return stroke shortly after the impact (caused by the Interaction of a sensor unit 38 with at least one marker 40 or 41, shown in FIG. 5, for example, in each case from two time marks, from which the period duration of the working cycle and the time interval between the two time marks of both the working stroke and the return stroke are determined in an evaluation 6 will.
The evaluation 6 is followed by a computer 7, with which, taking into account the size of the stroke section - which is assigned to the time stamps - the previously mentioned characteristic parameters (number of impacts, impact and return speed of the percussion piston, impact energy, impact power, reflection energy, reflection factor, position of the The impact level and the temporal change in the position of the impact level) are continuously determined and (apart from at most the impact and return flight speed of the impact piston) can be recognized and evaluated by means of a display unit 8.
Via the display unit, the operator 9 receives important information about the nature of the material to be processed 4, the wear at the tip 3a of the chisel 3, the guidance of the striking mechanism, the position and displacement of the impact level, the wear of the components determining the impact level and the Percussion performance.

Depending on the identifiable values of the parameters, the operator 9 can influence the position of the striking mechanism 2 with respect to the material 4 via the guide unit 5.

The hydraulic unit 1 is equipped with a controller 10, which allows the impact energy of the striking mechanism to be changed, for example by changing the hydraulic pressure. This is also assigned a controller 11, via which the number of strokes can be influenced in a known manner.

The values continuously determined by means of the computer 7 can - at least in part - be fed directly to the controllers 10, 11 as input variables. In addition or instead of this, the operator can act on the controllers 10 and 11 on the basis of the values of the parameters, which can be recognized by means of the display unit 8 - by adjusting the respective controller characteristic curve and thus improve or optimize the operating behavior of the striking mechanism 2.

The carrier device, to which the striking mechanism 2 is fastened in a positionally adjustable manner via the aforementioned guide unit 5, in the exemplary embodiment according to FIG. 4 consists of a crawler vehicle 12 with a pivotable platform 13; on this, on the one hand, the hydraulic unit 1 serving as an energy source and, on the other hand, a cabin 14 together with control station 14a for the operator are arranged.

The guide unit 5 has a plurality of swivel arms 15, 16, 17 a / b which can be moved by hydraulic cylinder units 18, 19 and 20 acting on them, and a holder 21 connected to the striking mechanism 2. This is simultaneously connected to the swivel arms 16 and 17b articulated. The swivel arm 15 is rotatably supported on a support part 22, which in turn is adjustable in height with respect to the platform 13 by means of a hydraulic cylinder unit 23.

The control station 14a is connected to the striking mechanism 2 via a line bundle 24 - which contains hoses for the energy supply and measuring and control lines. A second line bundle 25 leads from the control station 14 a to the hydraulic unit 1; in addition to the pressure and return hoses, it also contains a control line.

The control station 14 a comprises the devices (explained with reference to FIG. 3) which enable the operating behavior of the striking mechanism 2 to be optimized, namely the display unit 8 together with the computer 7 and evaluation 6 and the controllers 10 and 11.

The striking mechanism 2 shown as an example in FIG. 5 has a striking piston 26 with a striking piston tip 26 a, which faces the chisel 3 and strikes the chisel in the impact plane SS during operation of the striking mechanism. The percussion piston 26 itself is guided in a cylinder 27, which is closed on its rear side 27 a, in the sense of the double arrow 28, in a longitudinally movable manner.
The drive-side end section of the percussion piston facing away from the percussion piston tip 26 a is designed as a hollow piston section 26 b, which partially projects into a gas space 29 filled with compressed gas, which can be connected to a compressed gas storage or a compressed gas source via a line (not shown) and can thus be refilled.
Under the action of the compressed gas, the percussion piston 26 is accelerated in the direction of impact (arrow 28 a) on the one hand during the working stroke and braked on the other hand during the return stroke (arrow 28 b).

Following the hollow piston section 26 b, the percussion piston has two shoulders 26 c and 26 d, which limit two oil spaces 30 and 31 in the axial direction with the cylinder. The oil space 30, which is also delimited by the hollow piston portion 26 b, is - in contrast to the oil space 31 - in the vicinity of the gas space 29.

The two oil chambers are each connected to a controller 34 via an annular recess 30 a and 31 a and an adjoining line 32 and 33, respectively. This produces, in a manner known per se, the periodic movement of the percussion piston 26 in the sense of the double arrow 28 in that it connects via a pressure line 35 a with a pressure oil source (ie with the hydraulic unit 1 shown in FIGS. 3 and 4) or with an unpressurized one Return line 35 b produces.
The controller 34 is also connected via a control line 36 to the controller 11 shown in FIG. 3. The number of strokes and the individual impact energy of the percussion piston 26 can be changed by means of the control signals generated by the latter.

On the back 27 a of the cylinder 27, a retaining bolt 37 is fastened, which projects into the hollow piston section 26 b and whose end section 37 a facing the percussion piston carries a contactlessly working sensor unit 38 with a sensor head (not shown here). The sensor unit is connected to the evaluation 6 shown in FIG. 3 via a measuring line 39 which is passed through the holding bolt 37.

; Fig. 2 a, b) stellt eine Konstante dar, deren Größe bekannt ist und bei der fortlaufenden Ermittlung der charakteristischen Kenngrößen des Schlagwerks mitberücksichtigt wird.The sensor unit 38 is assigned two markings arranged at a distance from one another in the direction of movement of the percussion piston 26; these consist of annular grooves 40 and 41, which are provided in the bore wall 26 e of the hollow piston section 26 b.
The annular grooves 40 and 41, which are aligned transversely to the percussion piston longitudinal axis 45, are arranged with respect to the sensor unit 38 in such a way that they are active during the working stroke (Arrow 28 a) shortly before the impact piston strikes the chisel 3 and during the return stroke (arrow 28 b) shortly after the point of impact interact with the sensor unit and thereby each two successive time stamps (t₁, t₂ or t₃, t₄ generate in Fig. 2a, b); these are fed to the evaluation 6 (cf. FIG. 3) via the measuring line 39. The mutual spacing of the ring grooves 40 and 41 ( $\text{Δs = s₁ - s₂}$

; 2 a, b) represents a constant, the size of which is known and is taken into account in the continuous determination of the characteristic parameters of the striking mechanism.

In the embodiment in question, the measuring unit for determining the time intervals between the time marks of interest here is designed in such a way that the sensor unit 38, which has only one sensor head, moved the movement of the percussion piston 26 past it during the working stroke and the return stroke Markings (ring grooves 40 and 41) are scanned in a contact-free manner and converted into impulse-like timestamps.

6 a to c, the time stamps are generated by optical scanning of the movement of the percussion piston 26 in the direction of the double arrow 28. On the bore wall 26 e of the hollow piston section 26 b, the ring grooves 40 and 41 already mentioned are attached as markings. The sensor unit 38 has a sensor head 38 a consisting of incoming and outgoing light fibers 42 or 43 on, the end portions 42 a and 43 a are arranged in a plane transverse to the percussion piston longitudinal extension and protrude into the hollow piston portion 26 b.
The measuring line 39, which receives the light fibers 42 and 43 (cf. FIG. 6 c), opens into the evaluation 6 (cf. FIG. 3). In the present case, this additionally comprises a light source which acts on the supplying light fibers 42. The light emerging at the end sections 42 a strikes the bore wall 26 e, is reflected there, detected by the end sections 43 a and returned to the evaluation via the optical fiber 43; In this, any deviations that occur can be continuously determined by comparing the returned light quantity with a predetermined light quantity setpoint. As soon as one of the two annular grooves 40 or 41 is detected by the sensor head 38 a on the basis of the movement of the percussion piston 26, the value of the quantity of light fed back into the evaluation 6 changes, ie the instantaneous actual value deviates from the predetermined target value. This brief disturbance represents one of the time stamps to be processed further (cf. FIG. 2 b).
The effect of the ring grooves 40 and 41 - which, viewed in the longitudinal direction of the percussion piston, preferably have a small width - can, if necessary, be supported or improved by suitable coloring, coating or lining.
6 b shows, the end sections 42 a and 43 a of the light fibers are advantageously arranged over the entire circumference of the sensor head 38 a, the end sections 42 a and
Alternate 43 a. Their diameter and thus the length of the sensor head in the direction of the percussion piston longitudinal extension should be as small as possible in view of the highest possible resolution accuracy.

The markings interacting with the sensor head can also be designed differently. In particular, the annular grooves 40 and 41 can each be replaced by an insert body which has a different degree of reflection than the bore wall 26 e outside of this insert body.

The measuring unit for generating the required time stamps can also be designed in such a way that the sensor head 38 a is arranged in a recess 44 of the cylinder and in the circumferential surface of the piston shoulder 26 c - lying transversely to the longitudinal piston axis 45 - two annular grooves 46, 47 are attached (Fig. 7).
The two time stamps during the working stroke and during the return stroke are triggered in that the annular groove 47 and 46 or 46 and 47 move past the sensor head 38 a one after the other.
This can be constructed in the manner described above (cf. FIGS. 6 a to c) from a plurality of light fibers or also from a large number of light fibers, the end sections of which in the bore 44 face the percussion piston 26. Depending on the number of adjacent optical fiber end sections (cf. FIGS. 6 a to c), the sensor head 38 a extends over a smaller or larger part of the circumference of the percussion piston.

In the embodiment according to FIG. 8, the time stamps are caused by a sensor unit with two sensor heads 38 a, 38 b, to which a single marking attached to the percussion piston 26 is assigned (FIG. 8). This consists of the circumferential edge 26 f of the paragraph 26 c, which faces the gas space 29.
The movement of the percussion piston during the working stroke (arrow 28 a) has the result that the circumferential edge 26 f triggers two time marks in succession, first in cooperation with the sensor head 38 a and then with the sensor head 38 b; during the return stroke (arrow 28 b), the sensor heads interact with the peripheral edge in reverse order.
Deviating from the illustration, the sensor heads 38 a and 38 b can also be assigned a different design, in particular in the form of an annular groove or an insert body with a different degree of reflection.

voneinander angeordnet sind - hat zur Folge, daß über den zugehörigen einzigen Sensorkopf 38a während des Arbeitshubes und des Rückhubes kurz vor und kurz nach dem Aufschlag (Zeitpunkt t_A in Fig. 11a) zwei Zeitmarken t₁ und t₂ bzw. t₃ und t₄ ausgelöst werden (Fig. 11b); deren gegenseitiger Zeitabstand t₂ - t₁ bzw. t₄ - t₃ ist proportional zur Kolbengeschwindigkeit auf dem Hubwegabschnitt Δs und gibt angenähert die Auftreff- bzw.
Rückfluggeschwindigkeit wieder.
Bedingt dadurch, daß sowohl die Ringnuten 40, 41 bzw. 46, 47 als auch der Sensorkopf 38a in Bewegungsrichtung des Schlagkolbens eine geringe Längserstreckung aufweisen, stellen die Zeitmarken t₁ bis t₄ impulsartige Signale dar, die kurzzeitig am Ausgang des Sensorkopfes 38a anliegen.The equipment of the hollow piston section 26b (FIG. 9) or the percussion piston 26 (FIG. 10) with two annular grooves 40, 41 or 46, 47 - that in the direction of movement of the percussion piston at a distance $\text{Δs = s₁ - s₂}$

are arranged from one another - has the result that two time stamps t 1 and t 2 or t 3 and t 3 are triggered via the associated single sensor head 38 a during the working stroke and the return stroke shortly before and shortly after the impact (time t _A in FIG. 11 a) ( 11b); the mutual time interval t₂ - t₁ or t₄ - t₃ is proportional to the piston speed on the stroke section Δs and gives approximately the impact or
Return flight speed again.
This is due to the fact that both the ring grooves 40, 41 or 46, 47 and the sensor head 38a have a small amount in the direction of movement of the percussion piston Have longitudinal extent, the time stamps t₁ to t₄ represent pulse-like signals that are briefly present at the output of the sensor head 38a.

The device for determining characteristic parameters can also be designed such that a single annular groove 40 (FIG. 12) or 46 (FIG. 13) in the end section 37a of the retaining bolt or in the cylinder 27 itself has two sensor heads 38a, 38b with a mutual distance Δs are assigned in terms of control technology. This has the result that the first in the direction of impact of the percussion piston 38a sensor in Fig. 14c and the second sensor head 38b trigger the time stamps shown in Fig. 14b t₁, t₄ and t₂, t₃. The size of the time interval between the time stamps t₂ and t₁ or t₄ and t₃ again approximates the size of the impact or return flight speed of the percussion piston.

The time stamps t₁ to t₄ can also be generated in that a single sensor head 38a in the end section 37a of the retaining bolt (FIG. 15) or in the cylinder 27 (FIG. 16) is opposite a single annular groove 48 or 49, the longitudinal extension of which in the direction of movement Percussion piston coincides with the stroke path section Δs (cf. also FIG. 17a).
Such an embodiment leads to the generation of a working stroke signal AS 1 or return stroke signal RS 2, the duration of which is determined by the time interval between the associated time stamps t₂, t₁ or t₄, t₃ (cf. FIG. 17b). The time marks form the start and end range of the signals AS 1 and RS 2, ie their rising or falling edge.

In the embodiment according to FIGS. 18 and 19, two sensor heads 38a, 38b arranged at a distance Δs from each other interact with a single annular groove 50 and 51, the longitudinal extent of which in FIG Direction of movement of the percussion piston at least by the percussion piston path a₀ between the end point s₂ of the working stroke section or the starting point s₂ of the return stroke section and the theoretical impact point s _{A is} greater than the mutual distance of the sensor heads already mentioned (cf. FIG. 20a).
The relative movement between the sensor heads 38a, 38b and the correspondingly long annular groove 50 and 51 leads to the generation of the signals MS 1 and MS 2 shown in FIGS. 20c and 20b.
The duration of the signal MS 1, which is applied to the first sensor head 38a in the direction of impact (FIGS. 18 and 19), corresponds to the time interval between the time marks t₄ and t₁, the duration of the signal MS 2 to the second sensor head 38b the time interval between the Time stamps t₃ and t₂.
By comparing the signals MS 1 and MS 2, the length of time that the percussion piston needs to travel through the working stroke or return stroke section Δs can be calculated (cf. FIG. 20a).
Figures 20a to c apply in the event that the impact point S _{A of} the percussion piston lies exactly in the theoretically assumed impact level.

The representations according to FIGS. 21, 22 and 23a to c relate to the embodiments according to FIGS. 18 and 19 with the special feature that the percussion piston hits the chisel 3 at a later point in time (see, for example, FIG. 5) as is determined by the percussion piston travel a _O following the stroke travel section Δs (FIG. 23a).
This deviation manifests itself in a fundamentally changed course of the signal at the first sensor head 38a (FIG. 23c); This breaks down into the partial signals MS 1 'and MS 1'', the start and end area (corresponding to their rising and falling edge) from the time stamps t₁, t'₄ and t'₁, t₄ is formed. The time interval between the two partial signals MS 1 'and MS 1''(i.e. the time difference between the two time stamps t'₁ and t'₄) increases with increasing deviation of the point of impact from the theoretical level of impact (cf. Fig. 23a) .
The embodiment in question (according to FIGS. 18, 19 and 21, 22) thus makes it possible to qualitatively record deviations from the theoretical impact level on the basis of the course of the signal at the first sensor head and to intervene accordingly in the workflow:
If the signal at the first sensor head 38a disappears while the signal is still present at the second sensor head 38b, there is a deviation a between the point of impact and the theoretical level of impact. This information, which can be made optically recognizable, can be used, for example, by an operator to change the position of the striking mechanism with respect to the material to be processed by adjusting the guide unit in such a way that the aforementioned deviation of the impact point disappears.

The subject of the invention can also be designed in such a way that suitable time stamps can be obtained by discharging between electrodes located at a distance from one another (FIGS. 24a, b).
The sensor unit has a sensor head 38a in the form of an electrode, which is attached to the end section 37a of the retaining bolt 37 and projects laterally beyond it, forming under the circumferential edge, in the direction of the hollow piston section 26b of the percussion piston 26. The sensor head 38a is connected to the core 53a of a high-voltage cable 53 via an electrically conductive wire 52 which is passed through the non-conductive retaining bolt 37. Whose metallic outer jacket 53b is shielded from the core 53a by insulation 53c. The outer jacket 53b serving for electrical feedback is connected on the one hand via a line 54 to the rear 27a of the cylinder 27 and on the other hand to the earth potential of a high-voltage source 55 (shown schematically in FIG. 24b).
The electrical connection between the cylinder 27 and the hollow piston section 26b is established by a conductive piston ring 56 fitted in the cylinder; this may have openings through which the annular recess 30a is connected to the gas space 29.

On the bore wall 26e of the hollow piston section, two ring-shaped projections 57, 58 are formed as markings, which - seen in the longitudinal direction of the percussion piston 26 - are spaced apart by the distance Δs.
The projections 57, 58 represent electrodes which trigger an electrical discharge if the sensor head 38a - triggered by the movement of the percussion piston 26 - faces you.

The essential components of the high-voltage source 55 include a high-voltage generator 59, two load resistors 60 and a capacitor 61 connected in parallel therewith; the latter is simultaneously connected to one of the two outputs 62a, b of the high voltage source. One of the load resistors 60 is also connected via a line 63 to the core 53 a of the high-voltage cable 53.
The high voltage generator 59 is supplied with energy (for example by means of an on-board electrical system, not shown) via connections 64a, b.

If the electrodes 38a and 57 or 58 move during the movement of the percussion piston 26 opposite (see Fig. 24a), the electrical potential between them increases so much that a spark discharge begins. The current flow associated with this produces a voltage drop across the load resistors 60, which can be tapped off at the outputs 62a, b via the capacitor 61 and can be evaluated in the form of a time stamp (cf. FIG. 3).
The advantage of this embodiment can be seen in the fact that it is equipped in the area of the striking mechanism with simple components which are less susceptible to faults and which, moreover, lie in the upper section of the cylinder receiving the percussion piston, which is not at risk of dirt.

5, the sensor unit can also be equipped with a sensor head 38a, which - constructed in the manner of a field plate - operates according to the magnetoresistive principle (Fig. 25a, b). Semiconductor materials are used here, which change their electrical resistance considerably if the magnetic field flowing through them changes.

In the embodiment mentioned here — opposite the bore wall 26e of the hollow piston section 26b — two semiconductor resistance elements 65, 66 are attached in the end section 37a of the retaining bolt 37. Together they form a differential resistance and are penetrated by the magnetic field (indicated by the field lines 67a, b) of a permanent magnet 67. The differential resistance of the semiconductor resistance elements 65, 66 arranged in the manner of a field plate remains constant as long as the cylindrical bore wall 26e is opposite the parts 65, 66. When the ring grooves 40, 41 pass as a result of the movement of the percussion piston, the magnetic flux of the field lines changes with the course of the field lines Semiconductor resistance elements 65, 66 and thus their electrical resistance.

The connections 68a to c of the semiconductor resistance elements 65, 66 are connected to a circuit 70 via a three-wire cable 69 (cf. FIG. 25b) - which is led outwards through the retaining bolt 37 (cf. also FIG. 5) , which is supplied with power via terminals 71a, b. The voltage changes that occur as a result of a change in resistance in parts 65, 66 can be tapped off at outputs 72a, b.
These voltage changes, which are triggered during the working and return stroke of the percussion piston by the passage of the two ring grooves 40, 41, can be converted into time stamps, as are shown, for example, in FIG. 2b.

The advantage achieved by the invention is that, based on simple measurement processes that are carried out shortly before and shortly after the impact of the percussion piston, a smaller or larger number of characteristic parameters of a percussion mechanism can be determined continuously, so that there is the possibility of adapt the operating behavior of the striking mechanism to changing operating conditions in the interests of optimization.
The invention can be implemented using sensor units with one or more sensor heads, which allow the size of the impact and return flight speed of the percussion piston to be determined directly and continuously from the movement of the percussion piston during the work and return stroke with good approximation.

Claims (12)

1. A method of determining characteristic parameters for the purpose of influencing the operating behaviour of a breaking mechanism which has a percussion piston and which when acted upon by a working fluid alternately performs a working stroke in the impacting direction and a return stroke, characterized by the following features:

   - the impingement velocity of the percussion piston shortly before and its return velocity shortly after impingement are determined by a relative movement, corresponding to the movement of the percussion piston, on each occasion producing time marks which are associated with a portion of the working stroke and return stroke respectively and which succeed one another at intervals of time, the intervals of time being determined between the successive time marks of the working stroke and return stroke;

   - on the basis of the values of the intervals of time between the successive time marks of the working stroke and the return stroke, having regard to the value of the particular portion of the stroke travel, a continuous determination is made of both the impingement velocity and rebound velocity and also of at least one of the further characteristic parameters: number of impacts, energy of impact, impact power, reflection energy, reflection factor, position of the plane of impingement and change in time of the position of the plane of impingement.
2. A method according to claim 1, characterized in that two time marks are produced during the working and return strokes respectively.
3. A method according to at least one of the preceding claims, characterized in that the time marks are produced by a relative movement between at least one sensor head and at least one marking scanned thereby.
4. A method according to claim 3, characterized in that two markings are scanned to produce the time marks during the working and return stroke respectively.
5. A device for determining characteristic parameters for the purpose of influencing the operating behaviour of a breaking mechanism having a cylinder (27) and a percussion piston (26) which slides therein and which is acted upon by a working fluid connectable via a control system alternately to a pressure source and to an unpressurized return alternately performs a working stroke in the impacting direction and a return stroke, for the performance of the method according to at least one of the preceding claims, characterized by the following features:

   - the cylinder (27) has a sensor unit (38) with which at least one marking (40, 41, 46, 47, 48, 49, 50, 51, 26f; 57, 58) applied to the percussion piston (26) can be brought into interaction, while by the action of the marking on the sensor unit the piston movement shortly before and shortly after the impingement of the percussion piston produces every time a number of time marks (t₁, t₂; t₃, t₄) on the basis of which the amount of time required for the associated portion (Δs) of the working and return strokes can be determined by means of an evaluating system (6);

   - connected to the evaluation (6) is a computer (7), by means of which, on the basis of the intervals of time determined between the time marks (t₁, t₂; t₃, t₄) of the working and return stroke respectively, a continuous determination is made, taking into account the value of the associated portion (Δs) of stroke travel, of the value of the impingement velocity (v_A) and the rebound velocity (v_R) and also of one of the following characteristic parameters: number of impacts (z), energy of impact (E_O), impact power (N), reflection energy (E_R), reflection factor (R), position of the plane of impingement (Δa) and change in time of the position of the plane of impingement (Δa/Δt).
6. A device according to claim 5, characterized in that the sensor unit (38) has a sensor head (38a) which operates in the direction of the cylinder bore and past which two markings (40, 41; 46, 47) can be moved backwards and forwards which succeed one another at a distance (Δs) in the direction of movement (arrow 28) of the percussion piston (26).
7. A device according to claim 5, characterized in that the sensor unit (38) has two sensor heads (38a, 38b) which are disposed at a distance (Δs) from one another in the direction of movement (arrow 28) of the percussion piston (26).
8. A device according to at least one of claims 5 and 7, wherein the rear end portion of the percussion piston (26) takes the form of a hollow piston portion (26b), characterized in that extending into the hollow piston portion is a retaining pin (37) which is aligned parallel with the longitudinal axis (45) of the percussion piston and which is attached to the cylinder (27) and bears the sensor unit (38) equipped with at least one sensor head (38a; 38b), the at least single marking being applied to the bore wall (26e) of the hollow piston portion (26b).
9. A device according to at least one of claims 5 and 7, characterized in that the sensor unit (38) has a sensor head (38a) past which a marking can be moved backwards and forwards, the sensor head or the marking being so disposed and its length in the direction of movement of the percussion piston (26) being such that the marking lies outside the operative range of the sensor head before the impacting piston (26) performing the working stroke (arrow 28a) or the return stroke (arrow 28b) has reached the point of impingement (s_A) or the top reversal point (s_O) respectively.
10. A device according to at least one of claims 5 and 7, characterized in that the sensor unit (38) has two sensor heads (38a, 38b) past which a marking (50; 51) can be moved backwards and forwards in the direction of movement (arrow 28) of the percussion piston (26), the marking having a length which is greater by at least the percussion piston travel (a_O) between the end point (s₂) of the portion (Δs) of the working stroke travel and the starting point (s₂) of the portion (Δs) of the return travel and the theoretical point of impingement (s_A) than the mutual distance (Δs) between the sensor heads in the direction of movement of the percussion piston.
11. A device according to at least one of claims 8 to 10, characterized in that the at least single sensor head (38a) and the at least single marking (57, 58) take the form of electrodes between which an electric discharge takes place when they approach as close as possible to one another, each sensor head being connected to a voltage source (55) acting on said head.
12. A device according to at least one of claims 8 to 10, characterized in that the at least single sensor head (38a) is constructed as a magnetic field depending resistor transmitter with at least one semi-conductor resistor element (65, 66) whose resistance changes as the at least single marking (40, 41) passes by.

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