EP0934804B1 - 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 fluid-operated impact device, in particular hydraulic hammer, consisting of a pressure medium-driven percussion with a reciprocating under the action 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 in addition to a Pressure monitor trained control valve is equipped.

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

The movement of the percussion piston in the direction of the working stroke or the opposite return stroke is caused by a control, which is assigned to the striking mechanism or integrated in this.
The control can be equipped in particular with a movable spool, which acts on two opposite in the direction of movement, different sized annular surfaces of the percussion piston, that the smaller (effective in return direction) annular surface constantly with the pressure line and the larger (effective in working direction) annular surface over the spool is alternately connected to the pressure line and the return line.

Since the pressure medium supply of the construction machines, which provide the input power for the downstream impact device, designed for the internal power requirement of the construction machinery itself, must be made for the commissioning of the impact devices each with a retrofitting with control units to the downstream impact device, in particular with regard to the working pressure to adapt to the supply unit of the relevant construction machine. This retrofitting may be expensive and requires, moreover, that suitable control units are available in each case.

From the document EP 0 752 297 A2 a generic impact device with a control valve is already known, which serves to adapt the impact device - to ensure the required for material shredding single impact energy - to a small pressure medium flow rate; This is done by means of a spring-controlled control valve, which is integrated into the percussion itself, characterized in that by increasing the outlet resistance reduces the stroke rate and thus an adjustment to the supplied pressure medium flow rate is brought about.

The known solution has the consequence that only under the aforementioned circumstances, an adaptation to the provided input power is made, the power for which the impact device is designed, can not be exploited. In the case of an oversupply of input power, the control valve is not effective in the sense of adaptation, so that - as already mentioned above - in addition a retrofit to the input power supplying construction machine itself must be made.

The invention has for its object to design a fluid-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 machinery.
In other words, the percussion device itself should be designed such that its percussion mechanism - regardless of the input power provided by the associated supply unit - is protected against inadmissible operating states in the sense of overstressing.

The object is achieved by a pressure-medium-operated impact device with the features of claim 1.

The solution underlying the innovation is that the control valve consisting of a pressure shut-off valve or of a pressure relief valve is in communication with the pressure line pressurized with the working pressure and the percussion mechanism - if the working pressure that arises due to the input power exceeds a predetermined maximum value - automatically shut down by either the pressure line blocked or the controller 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 with respect to the impact mechanism is switched so that this and its control is not exposed by the supplied pressure medium unduly high stress.
Since the percussion mechanism is shut down when required under the action of the pressure shut-off valve or the pressure limiting valve, which forms part of the guide unit or percussion mechanism itself, that is part of the percussion device, the percussion device can be used without retrofitting in connection with construction machines of different design with regard to their input power. Accordingly, the impact device is ready for use without the need to avoid any overuse retrofitting on site.
In the context of the invention, the pressure shut-off valve or the pressure relief valve can in particular also form part of the impact mechanism itself, which is integrated in this.
If the working pressure acting on the impact mechanism with the interposition of a pressure shut-off valve has an inadmissibly high value, the pressure shut-off valve is automatically transferred to its blocking position, whereby the energy supply to the impact device is interrupted. For their re-commissioning, it is then only necessary that the supplied from the supply unit input power - for example, by reducing the speed of the associated pump unit - is adjusted accordingly.

The subject invention may be further formed in such a way that the pressure shut-off valve or the pressure relief valve is connected via an additional line to the controller, that this is blocked when exceeding the set on Druckabschaltventil or pressure relief valve working pressure peak in one of its end positions (claim 2). This blockage can be brought about in particular by the fact that a control surface acting on the control is subjected to corresponding pressure under the action of the relevant control valve.
In the present embodiment, the Druckabschaltventil or the pressure relief valve acts directly on the controller with the result that this is finally held in a certain end position and thus the percussion no longer carries out more strokes.

The pressure shut-off valve may in particular be equipped with a double piston, which has, on the one hand, an effective provision in the direction of the open position and, on the other hand, an effective valve in the opposite direction; the latter is connected via a control line on the input side to the pressure line (claim 3).
Thus, if the applied to the input side of the Druckabschaltventils working pressure assumes an inadmissibly high value, the double piston moves against the action of the provision in the blocking position in which the connection between the input and output side is interrupted.

To monitor the working pressure, the pressure limiting valve is connected on the input side to the pressurized line acted upon by the working pressure, from which its switching line emanates (claim 4). Furthermore, the pressure relief valve may be designed and connected such that it blocks the control in the working stroke position in its open position after exceeding the maximum working pressure (claim 5).

Notwithstanding the above-mentioned embodiment, the pressure relief valve may also be connected via a switching line to the pressure line acted upon by the working pressure and the output side to a non-pressurized return line; the controller is designed such that it is blocked in the return stroke position, if the pressure relief valve when it exceeds the maximum operating pressure assumes its open position (claim 6).

The equipped with a pressure shut-off valve embodiment may be further designed so that the pressure shut-off valve is connected via a switching line with the pressure applied to the working pressure line and designed so that it exceeds the working pressure maximum occupies the blocking position with the result that the Pressure shut-off valve connected Umsteuerleitung for the transfer of the control is blocked in the working stroke position (claim 7).

To ensure that the hammer mechanism is always protected against an inadmissibly high working pressure, despite the use of the pressure shut-off valve or pressure relief valve, it should be structurally designed for the highest possible pressure provided with the input power. This point of view can be met in that the percussion is structurally (by appropriate design of its wall thickness and its remaining components) designed statically for the highest possible pressure. This can be determined with regard to the relevant characteristic values of the construction machines or associated supply units which are introduced in the market and which could be considered for interaction with the impact device.

It goes without saying that in terms of the size of the input power supplied autonomous percussion device should have quick-change devices over which can easily connect to the pressure and the return line of each associated supply unit can be produced.

The invention will be explained in detail with reference to embodiments shown in the drawings.

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, 1 a 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, 1 a dargestellten Schlagvorrichtung) mit einem Druckabschaltventil, welches bei Überschreiten des Arbeitsdruck-Höchstwerts die Steuerleitung der Steuerung blockiert.

Show it:

Fig. 1

schematized a designed as a hydraulic excavator carrier device to which a pressure-medium-operated impact device is mounted adjustable;

Fig. 1a

as a schematic image of the impact device shown in Figure 1 together with control and additional control valve.

Fig. 2

as a schematic image, a control valve in the form of a pressure shut-off valve which is connected to the pressure line connected to the impact mechanism;

Fig. 3

a circuit diagram of the pressure-operated hammer mechanism, which is part of the impact device shown in Figure 1, 1 a and in which a control valve in the form of a pressure relief valve is integrated. this blocks in its open position after exceeding the maximum working pressure, the control in the working stroke position;

Fig. 4

a circuit diagram of the pressure medium operated percussion (as part of the impact device shown in Figure 1, 1a) with a comparison with Figure 3 differently connected pressure relief valve.

Fig. 5

a schematic of the pressure-driven hammer mechanism (as part of the impact device shown in Figure 1, 1a) with a control valve in the form of a pressure relief valve, which blocks the control in the return position if necessary.

Fig. 6

a circuit diagram of the pressure-driven hammer mechanism (as part of the impact device shown in Figure 1, 1a) with a pressure relief valve which connects the control line of the control with a non-pressurized return line when the maximum operating pressure. and

Fig. 7

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

The illustrated in Fig. 1 hydraulic excavator 1 is equipped with a supply unit 2 (consisting essentially of a diesel engine, not shown, and driven by this hydraulic pump), which - as known for example from the document DE 40 36 918 A1 - via a Pressure line 3 and a non-pressurized return line 4 (see Fig. 1 a) is connected to a fluid-operated impact device 5. The latter is adjustably held on the boom 6 of the hydraulic excavator with two boom arms 6a, 6b.
The impact device 5 has, as a guide unit, a support frame 7 which is articulated relative to the extension arm 6b and in which a percussion-driven impact mechanism 8 (for example shown in FIG. 3) is supported.
From the support frame 7 projects out a tool in the form of a chisel 9, which acts on the aforementioned percussion in a conventional manner.

In Fig. 1a is further shown schematically that the impact device 5, a controller 10 and - to adapt to the provided by the supply unit 2 available hydraulic input power - additionally designed as a pressure monitor control valve 11.

In the context of the invention, the control valve 11 may be part of the support frame 7 or the percussion mechanism 8 or integrated into the latter (cf., for example, FIG. 3).

In a particularly simple embodiment of the subject invention (as shown in FIG. 2), the control valve is designed as Druckabschaltventil 12 and connected to the connected to the percussion, acted upon by the working pressure pressure line 3.
As indicated in FIG. 1 a, the pressure shut-off valve 12 forms part of the support frame 7.

The pressure shut-off valve 12 has within a housing 13 a double piston 14; this is designed and connected such that it only connects the pressure line 3 with its output-side continuation 3a, 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 connected to the pressure line 3 control line 15; this opens on the side of the double piston 14 in a valve chamber 16, which is opposite to the acted upon by a return spring 17 page.
Under the action of said provision, the double piston has a tendency to occupy the illustrated open position, in which the lines 3 and 3a are interconnected, as long as in the valve chamber 16 acting on the double piston 14 counterforce does not exceed the restoring force. Otherwise, the double piston 14 moves (in the illustration) downwards and finally reaches the blocking position in which the connection between the lines 3 and 3a is interrupted. Accordingly, the striking mechanism 8 downstream of the pressure shut-off valve 12 (cf., for example, FIG. 3) is then shut down by switching off the energy supply.

The percussion device 8 which forms part of the percussion device 5 can be designed as desired in the context of the invention, in particular also with regard to its controller 10.
In the embodiment according to FIG. 3, the percussion mechanism 8 has a percussion piston 18, which is held reciprocably in the longitudinal direction within a working cylinder 19 and cooperates with the aforementioned chisel 9.
The percussion piston 18 has in the cylinder space of the working cylinder 19 lying on two piston collars 18a and 18b, which are separated by a circumferential groove 18c. The outwardly directed piston surface A1 and A2 of the piston collar 18b or 18a defines with the working cylinder 19 a rear and front cylinder space portion 19a and 19b, wherein the piston area A1 is dimensioned smaller than the piston area A2.

In contrast to the larger piston area A2, the smaller piston area A1 is constantly exposed to working pressure (system pressure) via a return line 20 extending from the continuation 3a of the pressure line 3. The opening 20a of the return line 20 is arranged with respect to the working cylinder 19 so that it lies in any case outside of the piston collar 18b and thus within the front cylinder chamber portion 19b. The cylinder chamber of the working cylinder 19 is (in Fig. 3 on the left side) provided with a conduit 21 which merges into the return line 4. The associated junction 21 a in the cylinder chamber is arranged such that it lies in the indicated impact position of the percussion piston 18 between the piston collars 18 a and 18 b.

The control (designated by "10" in FIG. 1a) for switching the movement of the percussion piston 18 consists of a 2/2-way valve 22; this has two differently sized control surfaces - namely, a smaller control surface S1 and a counter-directed to larger control surface S2. The smaller control surface S1 is connected via a control line 23 to the continuation 3a of the pressure line 3 and accordingly effective in the sense of a provision. The larger control surface S2 is connected via a reversing line 24 on the one hand to the output of a pressure relief valve 25 and on the other hand with the cylinder chamber in connection; its junction 24a is arranged with respect to the working cylinder 19 so that it is also in the illustrated Aufschlagstellung the percussion piston 18 between the two piston collars 18a and 18b. In this case, the junction 21a is further away from the front cylinder space portion 19b than the junction 24a. The pressure relief valve 25 is connected on the input side to the acted upon by the working pressure continuation 3a, via an additional line 26, from which also its switching line 25a starts.

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 the other on the output side via a reversing line 22a with the rear cylinder space portion 19a in connection.

Depending on the position of the percussion piston 18 within the working cylinder 19, the 2/2-way valve 22 is operated under the action of its control surfaces S1 and S2 so that it connects the rear cylinder chamber portion 19a alternately with the continuation 3a or the return line 4. This has the consequence that the percussion piston 18 is driven either in the working stroke direction (i.e., in the representation downward) or in the return stroke direction, counter to the return effect emanating from the smaller piston surface A1.

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

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 the input side via an additional line 28 - from which also its switching line 27a goes - with the continuation 3a of the pressure line 3 and the output side with a third control surface S3 of the 2/2-way valve 22 in conjunction. The third control surface S3 is also sized larger than the control surface S1 and effective for pressurization in the direction of the not shown working stroke position of the 2/2-way valve 22.
If the input side of the pressure relief valve 27 applied working pressure exceeds the predetermined maximum value, the pressure relief valve is transferred to the open position, not shown, with the result that the 2/2-way valve 22 finally occupies the working stroke position and is blocked in this, regardless of the position the percussion piston 18 within the cylinder space.
Due to the blocking of the control in the aforementioned end position, the percussion piston can not perform any further blows during this time.

The embodiment of FIG. 5 differs from the aforementioned embodiment of FIG. 4 in that the control is optionally blocked in another end position. In this case, the control in the form of the 2/2-way valve 22 via an additional line 30 is connected upstream of a pressure relief valve 29 with an on the input side into the additional line 30 opening switching line 29a.
On the output side, the pressure relief valve 29 is connected via the additional line 30 with a control surface S4 in connection. This is - as well as the smaller control surface S1 - effective in the direction of Rückhubstellung and dimensioned so that they together with the smaller control surface S1 optionally generates a greater restoring force than the effective in the opposite direction control surface S2.

Thus, if the input side of the pressure relief valve 29 applied operating pressure exceeds the predetermined maximum value, the pressure relief valve is transferred to the open position with the result that the 2/2-way valve 22 is held in the illustrated Rückhubstellung and further shocks of the percussion piston 18 are prevented.

The embodiment according to FIG. 6 also has a pressure limiting valve 31 (shown differently), which cooperates 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 with the non-pressurized return line 4 and on the other hand with the reversing line 24, which acts on the larger control surface S2. Furthermore, the pressure relief valve via a switching line 31 a control technology connected to the continuation of the pressure line 3 3a.
If the working pressure in the switching line 31 a exceeds the predetermined maximum value, the pressure limiting valve 31 is transferred from the illustrated blocking position to the open position and thereby relieved of pressure then connected to the return line 4 reversing line 24. This has the consequence that the 2/2-way valve 22 is held in the illustrated Rückhubstellung and the percussion piston 18 can perform no further working movements.
The advantage of this embodiment is the fact that the reversing line 24 is depressurized in the presence of an excessively high working pressure on the return line 4.

In the embodiment of FIG. 7, the control valve in the form of a Druckabschaltventils 33 is switched directly into the reversing line 24 of the 2/2-way valve 22, wherein the associated switching line 33a opens into the continuation 3a of the pressure line 3.

If the applied in the shift line 33a working pressure exceeds the predetermined maximum value, the pressure shut-off valve 33 is transferred from the illustrated open position to the blocking position, thereby blocking the Umsteuerleitung 24 toward the 2/2-way valve 22 and this held in an end position, thereby 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, wherein a possibly expensive retrofitting of the respective carrier device or the supply unit can be dispensed with. The embodiment of the invention has the consequence that the impact device is automatically stopped if the working pressure acting on it assumes an inadmissibly high value.
In order to ensure that the impact device is not unduly stressed even if the control valve does not function properly, the striking mechanism as a whole should be designed such that it can withstand the maximum pressure that can be generated by a suitable supply unit introduced on the market.

Claims (7)

1. Fluid driven percussion device (5), in particular hydraulic hammer, comprising a fluid driven percussion hammer (8) with a percussion piston (18) that can be moved back and forth acting upon a control means (10, 22) and with a guide unit (7) on which the percussion hammer is supported, whereby the percussion device (5) has additionally a control valve (11) acting as a pressure control in response to the supplied input power
   characterized in that
   the control valve (11) acting as a pressure shut-off valve (12, 33) or as a pressure-limiting valve (25, 27, 29, 31) - being a component of the guide unit (7) or the percussion hammer (8) itself - is connected to the pressure line (3) supplied with the operating pressure and stops the percussion hammer (8) automatically by either blocking the pressure line (3) or the control means (10) is hold in one of its end positions - that is the operating stroke position or the return stroke position - when caused by the input power the operating pressure exceeds a predetermined maximum value.
2. Device according to claim 1, characterized in that the pressure shut-off valve (12, 33) or the pressure limiting valve (25, 27, 29, 31) is connected to the control means (22) via an auxiliary pressure line (26, 28, 30, 32) such that the control means are blocked in one of its end positions when the maximum operating pressure set at the pressure shut-off valve or at the pressure limiting valve is exceeded.
3. Device according to claim 1 or 2, characterized in that the pressure shut-off valve (12) has a double piston (14) having on one hand a reset device (17) acting in a direction of the opened position and having on the other hand a valve chamber (16) acting in the opposite direction and being connected to the pressure line (3) via a control line (15) on the input side.
4. Device according to claim 2, characterized in that on the input side the pressure limiting valve (25, 27, 29) is connected to the pressure line (3a) supplied with the operating pressures and to the control line (25a, 27a, 29a).
5. Device according to claim 4, characterized in that the pressure limiting valve (25, 27) in its opened position blocks the control means (22) in its operating stroke position after the maximum operating pressure valve has been exceeded.
6. Device according to claim 2, characterized in that the pressure limiting valve (31) is connected to the pressure line (3a) supplied with the operating pressure on one hand via a control line (31a) and on the output side is connected to a pressure-free return flow line (4) on the other hand, whereby the control means (22) is formed such that it is blocked in the return stroke position assuming the pressure limiting valve (31) is in its opened position when the maximum operating pressure is exceeded.
7. Device according to claim 2, characterized in that the pressure shut-off valve (33) is connected to the pressure line (3a) provided with the operating pressure and being formed such that the pressure shut-off valve takes a barrier position when the maximum operating pressure values are exceeded with the consequence that the reverse line (24) connected to the shut-off valve (33) is blocked for a change over of the control means (22) in the operating stroke position.

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