EP0934804A2 - Fluid driven percussion device - Google Patents

Abstract

The hammer is fitted with a control valve to act as pressure monitor. The valve is formed as a pressure switch off valve or a pressure restricting valve (25) and forms a constituent part of the guide unit (7) or impact tool (8) and is connected to the pressure line (3) which is biased with the operating pressure. If the work pressure exceeds a predetermined maximum value the impact mechanism is automatically stopped in that either the pressure line is blocked or the control is fixed in one of its end positions, ie either the work stroke position or the return stroke position.

Description

The invention relates to a pressure medium-operated impact device, in particular hydraulic hammer, consisting of a pressure medium operated Striking mechanism with a back and forth under the influence of a control Percussion piston and a guide unit on which the striking mechanism is supported, the impact device to adapt to the supplied Input power additionally with a pressure switch Control valve is equipped.

Pressure medium-operated impact devices - which are used in particular for crushing stone, concrete or other building materials - are used in most cases as accessories or attachments for construction machines such as excavators, loaders or other carrier units.
Such an application is shown and described, for example, in document DE 40 36 918 A1, the impact device being fastened to the boom of a hydraulic excavator and connected to the supply unit of the hydraulic excavator via a pressure line and return line.
The guide unit itself supporting the striking mechanism can be designed as a housing (hammer box) or as a supporting frame.

The movement of the percussion piston in the direction of the working stroke or the opposite return stroke is brought about by a control which is assigned to the striking mechanism or is integrated therein.
The control can in particular be equipped with a movable control slide, which acts on two opposing ring surfaces of the percussion piston, which are opposite in the direction of movement, in such a way that the smaller ring surface (effective in the return stroke direction) constantly communicates with the pressure line and the larger ring surface (effective in the working stroke direction) the control spool is alternately connected to the pressure line and the return line.

Because the pressure medium supply to the construction machinery, which is the input power for the downstream impact device, for which The internal power requirement of the construction machinery itself is designed for the Commissioning of the impact devices each with a retrofit Control units are made to the downstream Impact device, in particular with regard to the working pressure to the Adapt the supply unit of the construction machine concerned. This Retrofitting can be complex under certain circumstances and also presupposes that suitable control units are available.

EP 0 752 297 A2 already has a generic type Knock device with a control valve known, which serves the Impact device - to ensure that for material shredding required single impact energy - to a pressure medium flow rate that is too small adapt; this is done by means of a spring-controlled Control valve, which is integrated in the striking mechanism itself, in that by increasing the outlet resistance, the number of strokes is reduced and thus brought about an adaptation to the pressure medium volume flow supplied becomes.

The known solution has the consequence that only among the previously mentioned circumstances an adaptation to the provided Input power is made, the power for which the Impact device is designed, can not be used. in case of a The control valve is not in the sense of an oversupply of input power Adjustment effective, so that - as already mentioned - an additional Retrofitting to the construction machine supplying the input power itself must be done.

The invention has for its object to design a pressure medium operated impact device of the type mentioned in such a way that it can be used without additional retrofitting with control units in connection with differently designed supply units for construction machines.
In other words, the striking device itself should be designed in such a way that its striking mechanism - regardless of the input power provided by the associated supply unit - is protected against impermissible operating states in the sense of overstressing.

The task is carried out by a pressure medium-powered impact device with the Features of claim 1 solved.

The idea of the solution on which the innovation is based is that the control valve, which consists of a pressure cut-off valve or a pressure relief valve, is connected to the pressure line to which the working pressure is applied, and the hammer mechanism - if the working pressure which arises due to the input power exceeds a predetermined maximum value - automatically stops that either the pressure line is blocked or the control is held in one of its end positions, namely the working stroke position or the return stroke position. Accordingly, the pressure shut-off valve or the pressure relief valve is switched with respect to the striking mechanism in such a way that the striking mechanism and its control are not subjected to impermissibly high stress by the pressure medium supplied.
Since the striking mechanism is stopped if necessary under the influence of the pressure shut-off valve or the pressure limiting valve, which forms a component of the guide unit or the striking mechanism itself, that is to say is a component of the striking device, the striking device can be used without retrofitting in connection with construction machines which are designed differently in terms of their input power. Accordingly, the impact device is ready for operation at the place of use without the retrofitting required to avoid any overstressing.
In the context of the invention, the pressure shut-off valve or the pressure limiting valve can in particular also form a component of the percussion mechanism itself, which is integrated into it.
If the working pressure acting on the striking mechanism with the interposition of a pressure shut-off valve has an inadmissibly high value, the pressure shut-off valve is automatically moved into its blocking position, as a result of which the energy supply to the striking device is interrupted. To restart it, it is then only necessary that the input power supplied by the supply unit is adapted accordingly, for example by reducing the speed of the associated pump unit.

The subject of the invention can be further developed in such a way that the pressure shut-off valve or the pressure relief valve is connected to the control via an additional line in such a way that when the maximum pressure set on the pressure shut-off valve or pressure relief valve is exceeded, it is blocked in one of its end positions (claim 2). This blocking can be brought about in particular by appropriately pressurizing a control surface engaging the control under the action of the control valve in question.
In the embodiment in question, the pressure shut-off valve or the pressure limiting valve acts directly on the control, with the result that it is finally held in a certain end position and the striking mechanism therefore no longer performs any further strikes.

The pressure cut-off valve can in particular be equipped with a double piston, which on the one hand has a reset effective in the direction of the open position and on the other hand a valve chamber effective in the opposite direction; the latter is connected on the input side to the pressure line via a control line (claim 3).
If the working pressure at the input side of the pressure cut-off valve assumes an impermissibly high value, the double piston moves against the effect of the reset to the blocking position, in which the connection between the input and output side is interrupted.

The pressure relief valve is used to monitor the working pressure on the inlet side to the pressure line pressurized with the working pressure connected, from which his switching line also starts (claim 4). Furthermore, the pressure relief valve can be designed and switched in this way be in its open position after exceeding the maximum working pressure the control in the working stroke position blocked (claim 5).

Deviating from the previously mentioned embodiment, this can Pressure relief valve also via a switching line to the with the Pressure line pressurized at the working pressure and on the outlet side to an unpressurized Return line must be connected; the control is like this trained that it is blocked in the return stroke position, if that Pressure relief valve when the maximum working pressure is exceeded Assumes open position (claim 6).

The embodiment equipped with a pressure cut-off valve can be further configured such that the pressure cut-off valve via a Switching line with the pressure line pressurized with the working pressure connected and designed such that it is exceeded when the Working pressure maximum value takes the blocking position with the result that the the pressure cut-off valve connected changeover line for the transfer the control is blocked in the working stroke position (claim 7).

To ensure that the striking mechanism - despite using the Pressure cut-off valve or pressure relief valve - in any case against is protected against an impermissibly high working pressure, it should be constructive for be designed for the greatest possible pressure, which with the input power for Is made available. This point of view can be met be that the striking mechanism in constructive terms (by appropriate Dimensioning its wall thickness and its other components) statically for is designed for the greatest possible pressure. This can be determined with regard to the relevant parameters of the construction machinery or associated supply units that are launched on the market and that for the interaction with the impact device could be considered.

It goes without saying that the size of the supplied Input power autonomous impact device quick-change devices should have, via which a connection with the Pressure and return lines of the associated supply unit can be made.

The invention is illustrated below with reference to the drawing Exemplary embodiments explained in detail.

Fig. 1

schematisiert ein als Hydraulikbagger ausgebildetes Trägergerät, an dem eine druckmittelbetriebene Schlagvorrichtung anstellbar angebracht ist;

Fig. 1a

als Schemabild die in Fig. 1 dargestellte Schlagvorrichtung nebst Steuerung und zusätzlichem Kontrollventil;

Fig. 2

als Schemabild ein Kontrollventil in Form eines Druckabschaltventils, welches an die mit dem Schlagwerk verbundene Druckleitung angeschlossen ist;

Fig. 3

ein Schaltschema des druckmittelbetriebenen Schlagwerks, welches Bestandteil der in Fig. 1, 1a dargestellten Schlagvorrichtung und in welches ein Kontrollventil in Gestalt eines Druckbegrenzungsventils integriert ist; dieses blockiert in seiner Öffnungsstellung nach Überschreiten des Arbeitsdruck-Höchstwerts die Steuerung in der Arbeitshubstellung;

Fig. 4

ein Schaltschema des druckmittelbetriebenen Schlagwerks (als Bestandteil der in Fig. 1, 1a dargestellten Schlagvorrichtung) mit einem im Vergleich zu Fig. 3 andersartig geschalteten Druckbegrenzungsventil;

Fig. 5

ein Schemabild des druckmittelbetriebenen Schlagwerks (als Bestandteil der in Fig. 1, 1a dargestellten Schlagvorrichtung) mit einem Kontrollventil in Gestalt eines Druckbegrenzungsventils, welches erforderlichenfalls die Steuerung in der Rückhubstellung blockiert;

Fig. 6

ein Schaltschema des druckmittelbetriebenen Schlagwerks (als Bestandteil der in Fig. 1, 1a dargestellten Schlagvorrichtung) mit einem Druckbegrenzungsventil, welches bei Überschreiten des Arbeitsdruck-Höchstwerts die Steuerleitung der Steuerung mit einer drucklosen Rücklaufleitung verbindet; und

Fig. 7

ein Schaltschema des druckmittelbetriebenen Schlagwerks (als Bestandteil der in Fig. 1, 1a dargestellten Schlagvorrichtung) mit einem Druckabschaltventil, welches bei Überschreiten des Arbeitsdruck-Höchstwerts die Steuerleitung der Steuerung blockiert.

Show it:

Fig. 1

schematically shows a carrier device designed as a hydraulic excavator, on which a pressure medium-operated impact device is adjustably attached;

Fig. 1a

as a schematic image, the impact device shown in Figure 1 with control and additional control valve;

Fig. 2

a control valve in the form of a pressure cut-off valve which is connected to the pressure line connected to the striking mechanism;

Fig. 3

a circuit diagram of the pressure medium-operated impact mechanism, which is part of the impact device shown in Fig. 1, 1a and in which a control valve in the form of a pressure relief valve is integrated; In its open position, this blocks the control in the working stroke position after the maximum working pressure value has been exceeded;

Fig. 4

a circuit diagram of the pressure medium-operated impact mechanism (as part of the impact device shown in Fig. 1, 1a) with a pressure limiting valve switched differently compared to Fig. 3;

Fig. 5

a schematic image of the pressure medium-operated impact mechanism (as part of the impact device shown in Fig. 1, 1a) with a control valve in the form of a pressure relief valve, which blocks the control in the return stroke position if necessary;

Fig. 6

a circuit diagram of the pressure medium-operated impact mechanism (as part of the impact device shown in Fig. 1, 1a) with a pressure relief valve, which connects the control line of the control with a pressure-free return line when the maximum working pressure is exceeded; and

Fig. 7

a circuit diagram of the pressure medium-operated hammer mechanism (as part of the impact device shown in Fig. 1, 1a) with a pressure shut-off valve, which blocks the control line of the control when the maximum working pressure is exceeded.

The hydraulic excavator 1 shown in Fig. 1 is equipped with a supply unit 2 (consisting essentially of a diesel engine, not shown, and a hydraulic pump driven by this), which - as is known for example from the document DE 40 36 918 A1 - via a pressure line 3 and a pressure-free return line 4 (cf. FIG. 1a) is connected to a pressure medium-operated impact device 5. The latter is held in an adjustable manner on the boom 6 of the hydraulic excavator with two boom arms 6a, 6b.
The striking device 5 has, as a guide unit, a support frame 7 which is articulated with respect to the extension arm 6b and in which a pressure medium-operated striking mechanism 8 (for example shown in FIG. 3) is supported.
A tool in the form of a chisel 9 protrudes from the support frame 7, on which the impact mechanism mentioned acts in a manner known per se.

In Fig. 1a it is also shown schematically that the striking device 5th a controller 10 and - to adapt to that of the supply unit 2 provided hydraulic input power - additionally an as Pressure control valve 11 formed.

In the context of the invention, the control valve 11 can be part of the Support frame 7 or the striking mechanism 8 or integrated into the latter (See, for example, Fig. 3).

In a particularly simple embodiment of the subject matter of the invention (according to FIG. 2), the control valve is designed as a pressure cut-off valve 12 and is connected to the pressure line 3 connected to the striking mechanism and subjected to the working pressure.
As indicated in FIG. 1 a, the pressure cut-off valve 12 forms part of the support frame 7.

The pressure shut-off valve 12 has a double piston 14 within a housing 13; This is designed and switched in such a way that it connects the pressure line 3 with its outlet-side continuation 3a only if the working pressure in the pressure line 3 does not exceed a predetermined maximum value. For this purpose, the housing 13 is provided with a control line 15 connected to the pressure line 3; this opens out on the side of the double piston 14 into a valve chamber 16 which lies opposite the side to which a return spring 17 is applied.
Under the action of the aforementioned restoration, the double piston strives to assume the opening position shown, in which the lines 3 and 3a are connected to one another, as long as the counterforce acting on the double piston 14 in the valve chamber 16 does not exceed the restoring force. Otherwise, the double piston 14 moves (in the illustration) downward and finally reaches the blocking position in which the connection between the lines 3 and 3a is interrupted. Correspondingly, the impact mechanism 8 downstream of the pressure shut-off valve 12 in terms of control technology (cf. FIG. 3 for example) is then stopped by switching off the energy supply.

The striking mechanism 8 forming part of the striking device 5 can be of any desired design within the scope of the invention, in particular also with regard to its control 10.
In the embodiment according to FIG. 3, the striking mechanism 8 has a striking piston 18, which is held to move back and forth in the longitudinal direction within a working cylinder 19 and cooperates with the chisel 9 already mentioned.
The percussion piston 18 has two piston collars 18a and 18b lying in the cylinder space of the working cylinder 19, which are separated from one another by a circumferential groove 18c. The outwardly directed piston surface A1 and A2 of the piston collar 18b and 18a defines with the working cylinder 19 a rear and front cylinder space section 19a and 19b, the piston surface A1 being dimensioned smaller than the piston surface A2.

In contrast to the larger piston area A2, the smaller piston area is A1 via a starting from the continuation 3a of the pressure line 3 Reset line 20 constantly pressurized with working pressure (system pressure). The The mouth 20a of the return line 20 is in relation to the working cylinder 19 arranged such that they are in any case outside the piston collar 18b and thus lies within the front cylinder space section 19b. Of the The cylinder space of the working cylinder 19 is (on the left in FIG. 3) a line 21 which merges into the return line 4. The associated junction 21a in the cylinder space is arranged such that it in the indicated impact position of the percussion piston 18 between the Piston collars 18a and 18b.

10" bezeichnet) für die Umschaltung der Bewegung des Schlagkolbens 18 besteht aus einem 2/2-Wegeventil 22; dieses weist zwei unterschiedlich große Steuerflächen auf - nämlich eine kleinere Steuerfläche S1 und eine dazu entgegengerichtete größere Steuerfläche S2. Die kleinere Steuerfläche S1 ist über eine Steuerleitung 23 an die Fortsetzung 3a der Druckleitung 3 angeschlossen und dementsprechend im Sinne einer Rückstellung wirksam. Die größere Steuerfläche S2 steht über eine Umsteuerleitung 24 einerseits mit dem Ausgang eines Druckbegrenzungsventils 25 und andererseits mit dem Zylinderraum in Verbindung; ihre Einmündung 24a ist bezüglich des Arbeitszylinders 19 derart angeordnet, daß sie sich in der dargestellten Aufschlagstellung des Schlagkolbens 18 ebenfalls zwischen den beiden Kolbenbunden 18a und 18b befindet. Dabei liegt die Einmündung 21a weiter von dem vorderen Zylinderraumabschnitt 19b entfernt als die Einmündung 24a. Das Druckbegrenzungsventil 25 ist eingangsseitig an die mit dem Arbeitsdruck beaufschlagte Fortsetzung 3a angeschlossen, und zwar über eine Zusatzleitung 26, von der auch seine Schaltleitung 25a ausgeht. The control (in Fig. 1a with

10 ") for switching over the movement of the percussion piston 18 consists of a 2/2-way valve 22; this has two control surfaces of different sizes - namely a smaller control surface S1 and a larger control surface S2 opposed thereto. The smaller control surface S1 is via a Control line 23 is connected to the continuation 3a of the pressure line 3 and is accordingly effective in the sense of a reset The larger control surface S2 is connected via a changeover line 24 on the one hand to the outlet of a pressure relief valve 25 and on the other hand to the cylinder chamber, its opening 24a with respect to the working cylinder 19 arranged in such a way that it is also in the illustrated impact position of the percussion piston 18 between the two piston collars 18a and 18b, the orifice 21a being further away from the front cylinder chamber section 19b than the orifice 24a On the gas side, connected to the continuation 3a to which the working pressure is applied, via an additional line 26, from which its switching line 25a also originates.

The 2/2-way valve 22 is further configured such that it is on the one hand on the input side with the continuation 3a and the return line 4 and on the other hand, on the output side via a changeover line 22a to the rear one Cylinder space section 19a communicates.

Depending on the position of the percussion piston 18 within the Working cylinder 19 becomes the 2/2-way valve 22 under the influence of it Control surfaces S1 and S2 operated so that it is the rear Cylinder chamber section 19a alternately with the continuation 3a or Return line 4 connects. As a result, the percussion piston 18 - contrary to that emanating from the smaller piston surface A1 Restoring effect - either in the working stroke direction (i.e. in the illustration down) or in the return stroke direction.

The interposition of the pressure relief valve 25 ensures that the striking mechanism 8 is automatically stopped when the maximum working pressure specified on the pressure relief valve is exceeded.
If the working pressure at the pressure relief valve 25 exceeds the predetermined maximum value, the control valve mentioned establishes a connection between the lines 3a and 24. Depending on the position of the percussion piston 18 within the working cylinder 19, this has the consequence that the 2/2-way valve 22 is transferred to the working stroke position (not shown) under the action of the working pressure applied to the larger control surface S2 and is held in this position.
The integration of the pressure relief valve via the additional line 26 between the lines 3a and 24 has the consequence that the control in the form of the 2/2-way valve 22 is blocked and thus the impact device is stopped if the working pressure exceeds the maximum value set on the pressure relief valve 25.

In the embodiment according to FIG. 4, the control in the form of the 2/2-way valve 22 is likewise assigned a pressure limiting valve 27; this is connected on the input side via an additional line 28 - from which its switching line 27a also originates - to the continuation 3a of the pressure line 3 and on the output side to a third control surface S3 of the 2/2-way valve 22. The third control surface S3 is also dimensioned larger than the control surface S1 and is effective when pressure is applied in the direction of the working stroke position of the 2/2-way valve 22, not shown. If the working pressure applied to the pressure limiting valve 27 on the input side exceeds the predetermined maximum value, the pressure limiting valve is moved into the open position, not shown, with the result that the 2/2-way valve 22 finally assumes the working stroke position and is blocked in it, regardless of the position of the percussion piston 18 within the cylinder space.
Due to the blocking of the control in the mentioned end position, the percussion piston cannot carry out any further blows during this time.

The embodiment according to FIG. 5 differs from the previously mentioned embodiment according to FIG. 4 in that the control may be blocked in another end position. In this case, the control in the form of the 2/2-way valve 22 is preceded by an additional line 30, a pressure relief valve 29 with a switching line 29a opening into the additional line 30 on the input side.
On the output side, the pressure relief valve 29 is connected to a control surface S4 via the additional line 30. Like the smaller control surface S1, this is effective in the direction of the return stroke position and is dimensioned such that, together with the smaller control surface S1, it may generate a greater restoring force than the control surface S2 effective in the opposite direction.

If the pressure-limiting valve 29 is present on the inlet side Working pressure exceeds the specified maximum value, it will Pressure relief valve transferred to the open position with the result that the 2/2-way valve 22 is held in the illustrated return stroke position and further impacts of the percussion piston 18 are prevented.

The embodiment according to FIG. 6 also has a pressure limiting valve 31 (shown differently) which interacts with the control in the form of the 2/2-way valve 22.
The pressure relief valve 31 is connected via an additional line 32 on the one hand to the unpressurized return line 4 and on the other hand to the changeover line 24, which acts on the larger control surface S2. Furthermore, the pressure limiting valve is connected to the continuation 3a of the pressure line 3 in terms of control technology via a switching line 31a.
If the working pressure in the switching line 31a exceeds the predetermined maximum value, the pressure limiting valve 31 is transferred from the illustrated blocking position into the open position and the pressure-relief line 24 then connected to the return line 4 is relieved. The consequence of this is that the 2/2-way valve 22 is held in the return stroke position shown and the percussion piston 18 cannot carry out any further working movements.
The advantage of this embodiment can be seen in the fact that the changeover line 24 is relieved of pressure when the working pressure is too high via the return line 4.

In the embodiment according to FIG. 7, the control valve is in the form of a Pressure cut-off valve 33 directly into the changeover line 24 of the 2/2-way valve 22 turned on, the associated switching line 33a in the continuation 3a of the pressure line 3 opens.

If the working pressure in the switching line 33a is the specified one Exceeds the maximum value, the pressure cut-off valve 33 is removed from the transferred open position shown in the locked position, thereby the Reversing line 24 in the direction of the 2/2-way valve 22 blocked and this held in an end position, whereby further working movements of the Percussion piston 18 can be prevented.

The advantage achieved by the invention is, in particular, that the input power supplied from the outside can be adapted with simple technical means to differently designed and designed supply units, it being possible to dispense with the retrofitting of the respective carrier device or the supply unit which may be complex. The result of the embodiment of the invention is that the striking device is automatically stopped if the working pressure acting on it takes on an impermissibly high value.
In order to ensure that the striking device is not subjected to impermissible loads even when the control valve is not functioning properly, the striking mechanism as a whole should be designed in such a way that it can statically grow to the maximum pressure that can be generated by a supply unit that is being introduced into the market.

Claims (7)

Pressure medium-operated striking device (5), in particular hydraulic hammer, consisting of a pressure medium-operated striking mechanism (8) with a percussion piston (18) moved back and forth under the action of a control (10) and a guide unit (7) on which the striking mechanism is supported, the Impact device (5) for adaptation to the input power supplied is additionally equipped with a control valve (11) designed as a pressure switch,
characterized in that the control valve (11), which is designed as a pressure cut-off valve or as a pressure limiting valve and which forms a component of the guide unit (7) or of the striking mechanism (8) itself, is connected to the pressure line (3) pressurized with the working pressure and the striking mechanism ( 8) - if the working pressure resulting from the input power exceeds a predetermined maximum value - stops automatically either by blocking the pressure line (3) or by holding the control (10) in one of its end positions - namely the working stroke position or the return stroke position. Apparatus according to claim 1, characterized in that the Pressure cut-off valve or the pressure relief valve (25, 27, 29, 31) an additional line (26, 28, 30, 32) is connected to the controller (22) in this way is that if the pressure cut-off valve or Pressure relief valve set maximum working pressure in one their end positions is blocked. Apparatus according to claim 1 or 2, characterized in that the Pressure cut-off valve (12) is equipped with a double piston (14) on the one hand a reset effective in the direction of the open position (17) and on the other hand a valve chamber (16) acting in the opposite direction has a control line (15) on the input side with the Pressure line (3) is connected. Apparatus according to claim 2, characterized in that the Pressure relief valve (25, 27 29) on the inlet side to the one with the Working pressure pressurized pressure line (3a) is connected, from the also his switching line (25a, 27a, 29a) goes out. Apparatus according to claim 4, characterized in that the Pressure relief valve (25, 27) in its open position Exceed the maximum working pressure control (22) in the Stroke blocked. Apparatus according to claim 2, characterized in that the Pressure relief valve (31) on the one hand via a switching line (31a) to the pressure line (3a) pressurized with the working pressure and on the other hand is connected to a pressure-free return line (4) on the outlet side, wherein the controller (22) is designed such that it in the Return stroke position is blocked if the pressure relief valve (31) at Exceeding the maximum working pressure its opening position occupies. Apparatus according to claim 2, characterized in that the Pressure shut-off valve (33) via a switching line (33a) with the Working pressure pressurized pressure line (3a) connected and such is designed so that it exceeds the maximum working pressure Locked position with the result that the pressure cut-off valve (33) connected changeover line (24) for the transfer of the Control (22) is blocked in the working stroke position.

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