EP1776212B1 - Striking device, in particular a hydraulic hammer, driven by a pressure medium - Google Patents

Description

The invention relates to a fluid-operated impact device, in particular a hydraulic hammer, consisting of a pressure medium-driven percussion with a back and forth under the action of a control percussion piston and a guide unit on which the percussion is supported. The impact device further has a control valve designed as a pressure shut-off valve (DAV) or as a shut-off valve, which automatically stops the percussion mechanism if the working pressure that arises due to the input power exceeds a predefinable maximum value by either blocking the pressure line or blocking the control in one of its end positions, namely the working stroke position or the Rückhubstellung held. Finally, the percussion has a hydraulic catch buffer for braking the percussion piston when driving over a predetermined Aufschlagebene.

The device mentioned above is from the EP 0 934 804 A2 known. 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 machinery such as excavators, loaders or other carrier units. The connection of a percussion device to a boom of a hydraulic excavator and the supply of the impact device via a pressure line and a return line is already in the DE 40 36 918 A1 described. The impact mechanism supporting guide unit can be designed as a housing (hammer case) or as a support frame. The striking mechanism consists of a cylinder in which a percussion piston is guided, a cylinder cover and a hammer base, in which the chisel or the insertion end is mounted on wear bushes.

The percussion piston is designed as a differential piston, ie it has two opposing annular drive surfaces of different sizes. The lower drive surface over which the return stroke is triggered when pressurized, is constantly charged with a predetermined operating pressure. The upper drive surface over which the impact stroke is triggered by pressurizing, is subjected to the operating pressure or relieved to the tank pressure depending on the position of a spool. The impact stroke is possible because the upper annular drive surface is larger, so that when subjected to the operating pressure results in a direction of impact directed force. The moving piston displaces the so-called stroke displaced by the small ring drive surface oil in the direction of a space above the larger upper annular surface, which is also pressurized with the oil coming from the pump. During the return stroke, the oil flows from the pump only in the direction of the smaller area drive surface, whereas the oil from the larger area drive surface via a throttle or return orifice, which ensures a smooth running of the hammer, is discharged.

In particular, the impact mechanisms mentioned here still have a gas reservoir, namely a space under gas pressure into which the upper end face of the piston protrudes. The gas pressure in this space exerts on the piston an additional force acting in the direction of the impact stroke. The piston part located at the other end of the piston, including the front face there, projects into a so-called striking space, which is connected to the atmosphere.

The already mentioned above spool, which is preferably located in the lid, depending on the switching position, the area larger drive surface either with the flow, so that there is the operating pressure or relieved (the return stroke) this area through a line connection, the return to the tank.

Also, the spool of the control valve may have a piston with two drive surfaces, wherein one of the surface or partial surfaces is constantly acted upon by a flow pressure and the other surface is selectively applied to the flow pressure or relieved; in the latter case, a connection to Tank open. Due to the different size of the drive surfaces of the spool can be moved to one of its end positions.

That in the EP 0 934 804 A2 described pressure shut-off valve or pressure relief valve is connected to the pressure applied to the working pressure line and then sets, if the adjusting due to the input power working pressure exceeds a predetermined maximum, the percussion automatically by the fact that either the pressure line blocked or the controller in one of their end positions, namely the working stroke position or the Rückhubstellung held. In this way it is ensured that the percussion mechanism is not exposed to an unacceptably high load.

If the chisel is not at the material to be destroyed, or penetrates the chisel in a blow far into the material, the piston passes over in the direction of the stroke stroke its predetermined (theoretical) Hubaufschlagebene and penetrates after passing a certain distance with its lower drive surface or the lower piston collar in a designated hydraulic catch buffer, which slows down the piston before it can strike the lower part. This measure reduces the load on the components and prevents damage.

By the theoretical impact level is meant the plane at which the lower face of the piston contacts the upper face of the bit when the bit is at the stop, i. H. the theoretical impact position, is present. By passing over the theoretical impact plane, it is meant that the piston assumes a position at which the lower end face of the piston is below or (at the return stroke above) the theoretical impact plane.

Preventive of damage also acts by the control valve to block the pressure line or hold the controller in one of their end positions, as at too high a selected operating pressure too high piston acceleration and thus builds up too high impact energy.

However, the above-described embodiment has the following disadvantage: If the bit is not on the material to be destroyed or penetrates the chisel in a blow (too) into the material, so the piston moves in Schlaghubrichtung its theoretical Aufschlagebene by a certain amount, where he with its lower drive surface or the lower piston collar penetrates into the hydraulic catch buffer. In order to drive the piston out of the buffer in the return stroke direction, the hydraulic medium has to pass through a supply line into the space below the areal smaller drive surface. By driven over the theoretical impact level piston, the hydraulic fluid can flow only over a narrow gap between the lower piston collar and the cylinder bore. This gap presents a relatively high resistance in terms of a throttle, whereby the pressure in the pressure line, which communicates with said annulus increases, and thereby reaches a lying above the allowable operating pressure level, which leads to the actuation of the Druckabschaltventils. This means that the hydraulic hammer is turned off accidentally when lifting the percussion piston.

It is an object of the present invention to eliminate this disadvantage.

To solve this problem, the fluid-operated impact device is proposed according to claim 1, which is characterized in that a control surface of the control valve via a signal line is at least indirectly connected to the working cylinder and at least then to the return when the percussion piston passes over the theoretical impact level (TAE) in that, when the theoretical impact plane is passed over the control surface of the control valve, a pressure is applied which prevents the control valve from being switched over, the control valve or pressure shut-off valve remains deactivated at least until the percussion piston has been moved out of the hydraulic catch buffer. The measure that the present in the signal line of the control valve pressure is reduced to a level below the cutoff pressure set on the control valve, there is no unwanted shutdown, so that the piston are safely moved out during the first return stroke after entering the buffer can. The deactivation However, it should only be used in borderline situations, that is, for example, not when the hammer is working on hard material and the percussion piston does not significantly overturn its theoretical impact plane in the direction of impact. In these cases, it is even necessary to protect the hammer from overloading that the pressure shut-off valve remains active.

For the pressure reduction, there are several solutions, which are also the subject of the dependent claims and will be discussed in detail with reference to the embodiments.

Thus, a pressure reduction in the signal line can be made by connecting the signal line to the return line, with the connection to the flow being throttled or disconnected at the same time.

The deactivation of the pressure shut-off valve should preferably occur when the theoretical impact level has been overrun by a specific amount in the direction of impact. This can be detected by a provided in a working cylinder at a suitable location bore whose closing or opening by the percussion piston triggers the appropriate control (pressure reduction in the signal line).

Only when the operating state has changed so much that it can be assumed that the pressure has dropped to a normal level with the correct input quantity and only reaches values in the signal line which do not lead to the switching of the pressure shut-off valve, the reduction is canceled and reactivated the pressure shut-off valve to protect the impact device. Signaling for the cancellation of the pressure reduction in the signal line, for example, the extension of the piston collar from the hydraulic buffer or the crossing of the theoretical impact level by a certain amount against the direction of impact be. The present invention also relates to such fluid-operated impact devices that are equipped with an automatic Hubumschaltung that allows the percussion piston can perform strokes of different lengths and thus the impact energy per stroke is varied. In addition to acting as a control line upper transverse bore, which is called in stroke devices with a Hubumschaltung long stroke, there is a second lower transverse bore, namely the Kurzhubbohrung. If the chisel is not at the material to be destroyed or penetrates the chisel in a blow far into the material, so the piston passes in Schlaghubrichtung its theoretical impact level and provides a connection with a transverse bore, the Hubumschaltungs-bore after a certain way via an intended Kolbeneindrehung. Through the pressure relief of this Hubumschaltungs hole a connection between the long stroke and the short stroke is made via a Hubumschaltungs valve, so that the Kurzhubbohrung is now also active. During the return stroke of the spool is thus already switched to Schlaghubstellung when the piston collar releases the lower Kurzhubbohrung and connects with the acting on the lower piston drive surface operating pressure. According to the invention, the control line of the pressure shut-off valve is no longer connected directly to the flow line, but connected to the Hubumschaltungs line. As soon as the piston in Schlaghubrichtung overruns the theoretical Aufschlagebene by a certain amount and penetrates into the hydraulic catch buffer, which is connected to the Hubumschaltungs hole line and thus the signal line of the Druckabschaltventils relieved via the existing Kolbeneindrehung against the return. As a result, the pressure shut-off valve is deactivated.

Conceals the lower piston collar on the return stroke, the Hubumschaltungs hole and hereby separates the connection to the return so the Hubumschaltungs line is connected via a retaining hole in the Hubumschaltungs valve with the control line, in the return stroke of the spool with the return line in one embodiment Connection stands.

If, after deactivation of the shut-off valve, the control is switched to the stroke, the operating pressure prevailing in the control line is conducted via the retaining bore of the Hubumschaltungs valve in the Hubumschaltungs hole, after which the Hubumschaltungs valve switches to the long stroke position, in which the retaining hole Hubumschaltungs line connects to the pressure line. Through the hole in the Hubumschaltungs valve is achieved that even when closed by the piston Hubumschaltungs hole a certain level of pressure in the Hubumschaltungs hole is held and continue the recovery of the holding valve from the Kurzhubposition takes place in the long-stroke position.

When the piston reaches a certain position above the upper short-stroke reversal point in the return stroke, the piston releases the stroke changeover bore and establishes a connection of the bore with the lower supply groove, which is connected to the supply line.

For larger hammers Langhub- or Kurzhubbohrungen are not directly connected to the spool, but with the interposition of a holding valve, which connects the control line to the spool valve depending on the pressure level in the long stroke with the flow or return. The pressure shut-off valve is located in the control line either between the holding valve and the spool or between the holding valve and the long-stroke.

In the control line between the working cylinder interior and the spool, in which abuts the dependent on the piston position signal for reversing the spool, a holding valve is preferably arranged that connects the spool side line section with the flow or the return depending on the pressure in the working cylinder inner space side line section , In this case, either the pressure shut-off valve between the holding valve and the spool is disposed or between the working cylinder interior and the holding valve.

According to a further embodiment of the invention it is provided that the piston is a throttled connection between one with the. Supply line connected line releases to a line connected to the return as soon as the percussion piston passes over its upper or lower reversal point (or the impact position) by a certain amount.

Preferably, the control valve has a control surface, which is connected to the switching in Abschaltstellung so with a pressure level that an additional operating force is effective in the off position. This ensures that even after dropping the flow pressure or the signal pressure up to a certain Downshift pressure, which is below the set on the valve cut-off, the control valve is held in the off position.

Fig.1a

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

Fig. 1b

als Schemabild die in Fig. 1 dargestellte Schlagvorrichtung nebst Steuerung und zusätzlichem Kontrollventils,

Fig.2-16

jeweils Schaltschemata des druckmittelbetriebenen Schlagwerkes.

Further variants and advantages are described in the drawings. Show it:

1a

schematizes a trained as a hydraulic excavator carrier device to which a pressure-medium-operated impact device is mounted adjustable,

Fig. 1b

as a schema image the in Fig. 1 illustrated impact device and control and additional control valve,

Fig.2-16

each circuit diagrams of the pressure-driven hammer mechanism.

The in Fig. 1 a hydraulic excavator 1 is equipped with a supply unit 2, which consists essentially of a diesel engine, not shown, and a driven by this hydraulic pump and as for example from the DE 40 36 918 A1 known via a pressure line 3 and a non-pressurized return line 4 (see Fig.1b) is connected to a fluid-operated impact device 5, which is adjustably held on the boom 6 of the hydraulic excavator with two boom arms 6a, b.

The impact device 5 has as a guide unit with respect to the Auslegearmes 6b hinged mounted support frame 7, in which a pressure medium operated hammer mechanism 8 according to one of the embodiments FIGS. 2 to 15 is supported. From the support frame 7 of the chisel 9 protrudes, acts on the impact mechanism. As Fig. 1b can also be seen schematically, the impact device 5 has 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. The control valve 11 may be part of the support frame 7 and the striking mechanism 8. The Schlagwerk 8 after Fig.2 has a working cylinder 12 in which a percussion piston 13 is reciprocable. The percussion piston 13 has two piston collars 13a and 13b, which are separated by a circumferential groove 13c. The respective outwardly directed piston surfaces A1 and A2 of the piston collar 13a and 13b define with the working cylinder 12 a rear and a front cylinder chamber portion 12a and 12b. The piston area A1 is dimensioned larger than the piston area A2. The percussion piston 13 goes to its lower end in an end piece 13 d, which is a tool in the form of the chisel 9 opposite, whose range of motion is limited upwards by the stop 14. In the illustrated embodiment, the state is shown in which the percussion piston 13 strikes the chisel 9 with its end 13d in the region of the theoretical impact plane TAE.

To control the switching of the movement of the percussion piston 13, a control valve 15 is provided, the smaller slide surface S1 is constantly acted upon by a line 16 with the working pressure p, the pump 17 delivers. Via the line 3 is also the same working pressure p in the space 12b, so that the piston ring surface A2 is acted upon by this pressure.

The larger slide surface S2 of the spool 15 is connected via a control line 18 with the working cylinder interior in combination. This line 18 opens into a bore marked LH in the working cylinder interior, which is located as shown above the collar 13b of the percussion piston 13. In this control line 18, a pressure shut-off valve 19 is included, the associated throttle line 20 in the return line 4, which leads to the tank 21, opens. In this choke line 20, a throttle or orifice 22 is arranged, wherein in the line lying between the diaphragm 22 and the pressure shut-off valve still a signal line 23 opens, which is connected to a signal bore of the working cylinder.

The pressure shut-off valve 19 is an overload protection, which automatically stops the percussion mechanism, if the pressure exceeds a predetermined maximum value due to the input power. However, if the chisel 9 is not applied to the material to be destroyed or penetrates far into the material in a blow, can Operating conditions occur in which the piston can exceed its theoretical impact plane TAE by one measure in Schlaghubrichtung; the lower piston collar 13b penetrates in this case in the lower hydraulic catch buffer. In order to move the piston out of the buffer in the return stroke direction, the oil flowing through the conduit 3 or the bore 3a must flow through an annular gap between the lower piston collar 13b and the cylinder bore into the hydraulic catch buffer to pressurize the lower piston drive surface A2. The gap thus throttles the flow of oil, which causes the pressure in the pressure line to rise. Would be as according to the embodiment according to EP 0 934 804 A2 the control line of the Druckabschaltventils connected to the pressure line 3, this would lead to an unwanted shutdown of the hammer. If the piston does not substantially overtake the theoretical impact plane TAE, the bore connected to the signal bore 23 is constantly exposed to the pressure prevailing in the front cylinder section 12a, which is connected to the pressure line 3, via an axial groove in the piston collar 13b. If the percussion piston passes over the theoretical impact plane TAE by a certain amount, the piston collar 13b closes the bore connected to the signal line 23. Via the line 20 and the throttle 22, the signal line 23 is relieved to return. Thereby, switching of the valve 19 is prevented even if the pressure in the pressure line 3 can rise to a level higher than the cut-off pressure of the valve 19. This prevents the throttle line 20 with a throttle 22, which prevents a pressure increase in the signal line 23 and thus switching the Druckabschaltventils when moving out of the percussion piston from the hydraulic catch buffer. The embodiment according to Fig. 3 essentially corresponds to the embodiment according to Fig. 2 with the proviso that the pressure shut-off valve is a 3/2 valve which prevents signal propagation by disconnecting the connection between the bore LH via line 18 and the spool 15, and in addition the line section 24 connects to the return line 4.

In the embodiment according to Fig. 4 which according to the embodiment Fig. 2 corresponds, the throttle line 20, which contains the throttle 22, connected to the pressure line 3. However, the signal line 23 terminates in a bore, which then, when the piston overruns the theoretical impact plane TAE in Schlaghubrichtung by a certain amount of the collar 13b is exposed, so that a connection of the signal line is provided with the return. As a result of the pressure reduction achieved in this way, the pressure shut-off valve 19 is deactivated until the piston overruns the bore HU during its return stroke with its piston collar 13b, so that the oil from the supply, which flows via the conduit 3 and conduit 20 through the throttle 22, gradually restores the operating pressure level. the deactivation of the pressure shut-off valve is thus canceled.

In the embodiment according to Fig. 5 is in addition to the embodiment according to Fig. 4 a relief valve 25 is provided, which is arranged in a connecting line 26 between the signal line 23 and the return line 4. In this connection line, a throttle 27 is additionally arranged, wherein the control line 28 of the relief valve 25 bridges this throttle. The pressure reduction in the signal line 23 takes place when the piston overruns the release position in the stroke, whereby the connection of the connected to the signal line 23 bore released to the return line 4 and oil is discharged from the signal line 23. In a subsequent return stroke, even with the bore closed by the piston, the reduced pressure in the signal line 23 is maintained via the relief valve 25 connected in the passage position. The throttle cross sections, the cross section of the connection between the signal line and the flow and the switching pressure of the relief valve 25 are selected so that the pressure in the signal line only reaches a level at which the relief valve is switched into the blocking circuit when the piston during the return stroke has made a connection with the flow. Alternatively, starting from the embodiment according to Fig. 4 In addition, a pressure-holding valve 30 may be provided in the line 20, which alternatively produces a throttle connection of the signal line with the flow (line part 20a) or the return line (line part 20b) depending on the switching position (see Fig. 6 ). The valve 30 is actuated by the pressure in the line 23 via the line part 31. If the piston 13 overruns the theoretical impact plane TAE by a certain amount in stroke stroke direction, the stroke reversal bore HU is released by the piston collar 13b and connected to the return line 4.

As a result, the pressure in the signal lines 23 and the control line 31 drops, as a result of which the pressure-maintaining valve 30 switches into the relief position due to a restoring force, in which the signal line is throttled and connected to the return line. During the subsequent return stroke of the piston 13, even at a position in which the bore HU is closed, the reduced pressure in the signal line is maintained. The throttle cross section, the cross section of the connection between signal line and flow and the switching pressure of the relief valve 30 are selected so that when the piston 13 has made a connection of the signal line with the flow during the return stroke, the pressure in the signal line reaches a level at the pressure relief valve switches back to the pressure position, d. H. the pressure-holding valve 30 establishes a further throttled connection between the signal line and the supply line 3. In the following stroke stroke, the supply pressure in the signal line is maintained even when the signal bore is closed by the piston. The throttle cross-section, the cross section of the connection between the signal line and return and the switching pressure of the relief valve 30 are selected so that when the piston has made a connection of the signal line with the return line 4 at a dead stop, the pressure in the signal line reaches a level such that the relief valve switches back to the relief position.

In the embodiment according to Fig. 7 In addition, the hammer has a stroke switch, with which the piston can move different strokes depending on the operating state. As in the aforementioned embodiments, the line 23 is used here with the Hubumschaltungs hole HU as a signal line. The Hubumschaltungs-bore is disposed between the bore LH and KH, the HU-bore is released by the piston collar 13b during the stroke only and connected to a return line 4 when the theoretical impact level is crossed by a certain amount by the piston 13. This measure (ie the arrangement of the bore HU to the piston collar 13b) is chosen so that the piston collar 13b is not yet or just penetrates into the hydraulic buffer. During the return stroke of the piston collar 13b, the Hubumschaltungs bore free and connects them to the flow through the lower supply groove 32, as soon as the piston during the return stroke by a certain amount above the theoretical impact level TAE located. The line with the Hubumschaltungs hole HU and the piston collar 13b are designed so that the Hubumschaltungs hole is connected via the piston only to the supply line 3 when a position above the Kurzhubbohrung KH is reached. The Hubumschaltungs valve 33 is connected via the pressure in the Hubumschaltungsleitung HU against a counter force and connects the Hubumschaltungs-hole HU via a throttle 22 in the long-stroke position - as in Fig. 7 dargestelit - with the flow 3 and in the short-stroke position with the line in which the signal for reversing the spool 15 is present. By the throttled connection to the flow 3 it is achieved that the pressure in the Hubumschaltungs-bore, which has led to the switching of the valve in the long-stroke position, is also maintained when the Hubumschaltungs bore is covered by the piston. In the short-stroke position, the throttled connection of the Hubumschaltungs-bore HU with the control line LH is achieved that the low pressure level in the Hubumschaltungsbohrung HU, which has led to switching of the valve 33 in the short-stroke position is maintained, even if the Hubumschaltungsbohrung of Piston is covered. Furthermore, it is achieved by the retaining bore that the Hubumschaltungs valve 33 switches back into the long stroke position when in the control line, a pressure signal for switching the spool 15 is present in the stroke.

In the embodiment according to Fig. 8 are in contrast to the above-described embodiment, the long-stroke or short-stroke holes are not directly connected to the spool, but act on an additional holding valve 34, the control line to the control slide either with the flow 3 or the depending on the pressure in the LH bore Return 4 connects. The pressure shut-off valve 19 is arranged in the LH line 29. Alternatively, the pressure shut-off valve 19 may also be arranged between the node 35 and the holding valve 34, so that neither a short-stroke nor a long-stroke signal can act on the holding valve 34 when the pressure shut-off valve is switched.

At the in Fig. 9 illustrated embodiment, the pressure shut-off valve 19 is disposed in the control line 18 between the holding valve 34 and the spool 15. Furthermore, the retaining hole in the short-stroke position is no longer connected to the output of the Hubumschaltungs valve 36, but via a further valve port 37 to the control line, ie the line between the holding valve 34 and the spool 15 is connected. In the short-stroke position, the Hubumschaltungs-hole HU is throttled connected to the control line which is connected to the control surface of the spool 15. The throttled connection to the control line achieves that the low pressure level in the Hubumschaltungs-bore, which has led to the switching of the valve in the short-stroke position, is also maintained when the Hubumschaltungs bore is obscured by the piston collar 13b. Furthermore, it is achieved by the measure that the Hubumschaltungs valve 36 switches back to the long-stroke position when the spool 15 receives a pressure signal to switch to the stroke stroke.

In the 10 to 15 illustrated embodiments have in common that when the pressure exceeds the hammer is stopped via a valve 19 and further a second pressure relief valve 39 limits the pressure in the hammer flow line 3.

Thus, the embodiment corresponds to Fig. 10 the embodiment according to Fig. 2 with the proviso that the pressure relief valve 39 is arranged between the flow line 3 and the return line 4. When the hammer is shut off by the pressure cut-off valve 19, the flow pressure normally increases because the hammer does not decrease any oil. To ensure that the supply pressure does not exceed a certain level, the pressure limiting valve 39 limits the supply pressure. On the input side, the pressure limiting valve is connected to the pressure line 3. If the pressure in the flow exceeds the pressure set on the pressure relief valve, oil is led from the flow to the return. The set pressure of the pressure limiting valve 39 should be above the switching pressure of the pressure shut-off valve 19. The pressure relief valve can of course in a corresponding manner in the other embodiments after Fig. 1 to 9 be used in a corresponding arrangement.

At the in Fig. 11 illustrated embodiment, the pressure relief valve is not controlled directly by the pressure in the supply line 3, but by the pressure in the signal line 23 of the Druckabschaltventils 19. By appropriate pressure setting of the valves, namely a higher pressure set on the pressure relief valve switching pressure than the pressure shut-off valve is achieved that before the response of the pressure relief valve 39, the hammer is turned off. If the piston overruns the theoretical impact plane TAE by a certain amount in stroke stroke direction, then the pressure shut-off valve 19 and the pressure limiting valve are deactivated by relieving the signal line.

In the embodiment according to Fig. 12 the pressure relief valve is driven by the pressure in the supply line 3 only when the pressure shut-off valve has switched. With this measure it is achieved that before the response of the pressure relief valve 39, the hammer is turned off.

The embodiment according to Fig. 13 corresponds to the embodiment according to Fig. 11 with the proviso that in the valve 40, the pressure limiting function has been integrated in the pressure shut-off valve. With increasing pressure in the signal line, the pressure line 3 is initially blocked and optionally relieved to return if, in addition, a connection between the flow and the return is opened with increasing pressure. The pressure limiting valve integrated in the valve 40 is effective only when the pressure shut-off valve of the valve 40 has turned off the hammer.

In the embodiment according to Fig. 14 a check valve 41 in the form of a leak-free seat valve is used to separate the hammer from the pressure line 3 when the pressure exceeds a predetermined value in the signal line 23. The signal line 23 is connected via a throttle 42 with the pressurized line, namely the flow 3 and is relieved to the return 4 when the percussion piston 13 in the direction of impact the theoretical impact plane TAE passes by a certain amount. In the switched state, the valve 41 is provided with a holding function which separates the control surface of the valve from the signal line and with the pressure in the lead 3 connects. This measure prevents the valve from switching back when the supply and the pressure drop behind the valve.

In the embodiment according to Fig. 15 a valve 43 is provided, which relieves the line behind the valve in addition to the return 4 as a leaking oiled slide valve in the switched state. The shut-off valves after Fig. 14 and 15 can also after in one of the circuit arrangement Fig. 2 and 3 be controlled in the corresponding manner, the piston 13 in idle the connection of the signal line to the supply line 3 separates and the signal line is connected via a throttle not with the flow, but the return 4.

The shut-off valves after Fig. 14 and 15 can also for maintaining the pending in the signal line pressure at the piston closed Hubumschaltungs hole HU with auxiliary valves according to the embodiments according to Fig. 5 and 6 Furthermore, the signal line can be connected to the Hubumschaltungs hole HU, as shown in Fig. 7 to 9 is shown.

In the embodiment according to Fig. 16 the control valve 44 locks the control line and relieves it to the return 4, so that the controller switches to return stroke. The control valve 44 has three control surfaces, wherein two control surfaces S _{1 '} and S _2' and the provision (spring 45) of a third control surface S _{3 'are} opposite. The sum of the areas of the two rectified control surfaces S _{1 '} and S _2' corresponds to the area of the third control surface S _{3 '} . The two larger, opposing control surfaces S _{2 '} and S ₃ - are connected to each other via a throttle 46, wherein the larger control surface S _{3' is} connected to the signal line. The smaller control surface S _{1 '} is depressurized, z. B. by a connection with the return. Compared to the control valve after Fig. 3 the control valve 44 has a further connection 48, with which the middle control surface S _{2 '} can be connected in shutdown position with the return. In the operating position, the control surfaces cause a provision by spring 45 opposing force, with only one surface is effective, which corresponds to the control surface S _{1 '} . If the control valve is in Shut-off switched, the middle surface S _{2 '} via the connection 48 to the return 4 is connected. Oil flowing from the signal line and via the throttle 46 to the control surface S _{2 '} is discharged via the port 48 to the tank 21. As a result, the two rectified surfaces S _{1 '} and S _{2' are} relieved of pressure and the provision of the return force is generated by the large control surface S _{3 '} . Even if the pressure in the signal line drops below the reset pressure due to the reset, the valve remains in the shutdown position until it falls below a certain setback pressure. The spool thus remains switched to return stroke until falling below a return pressure and the percussion piston moves against the Schlaghubrichtung against its mechanical stop. Furthermore, in the working cylinder 12 connected to the return 4, striking the working cylinder interior bore T is arranged so that the percussion piston this hole T releases when the percussion piston passes through his determined by the LH bore upper reversal point by a certain amount. As a result, oil from the lower supply groove 32, which is connected via the bore 3 a to the pressure line 3, flow off via the aperture 47 to the return 4. The aperture 47 is dimensioned so that when the impact mechanism is switched off, the pressure resulting in the pressure line 3 does not exceed the permissible operating pressure, but the pressure is sufficient to keep the shut-off valve in the shut-off position.

Claims (10)

1. A fluid-powered impact device (5), especially hydraulic hammer, consisting of a fluid-powered impact mechanism (8) provided with a hammer piston (13) that can be moved back and forth by means of a controller and provided with a control valve, designed as pressure-limiting valve (19) or blocking valve automatically deactivating the impact mechanism if the working pressure caused by the input pressure exceeds a predetermined peak value by either blocking in the pressure line (3) or stopping the controller in one of its end positions, that is either the position of the working stroke or of the return stroke, further provided with a hydraulic stop butter for deceleration the hammer position (13) when a predetermined impact area (TAE) is passed,
   characterized in that
   a control area of the control valve (19) is at least indirectly connected with the working cylinder (12) by a signal line (23) and at least indirectly connected with a return line, if the hammer piston (13) passes the predetermined impact plane (TAE), so that the control area of the control valve is pressurized while passing the theoretical impact plane (TAE), that avoids a reversal of the control valve, so that the control valve is deactivated at least when the hammer piston (13) moves out of the hydraulic stop buffer.
2. Impact device according to claim 1, characterized by being deactivated by means of a reduction of the pressure in the signal line of the control valve, preferably the pressure-limiting valve (19), to a value below the limit of the shut-off pressure set for the control valve.
3. Impact device according to claim 1 or 2, characterized in that the pressure level can be maintained by means of an auxiliary valve (25, 30, 33, 34, 36, 39) and/or a throttle (22, 27, 42) after the realization of the pressure level required in the signal line to the pressure-limiting valve for deactivation the pressure-limiting valve (19) at least until the piston (13) has reached or passed the theoretical impact plane (TAE) in its return stroke.
4. Impact device according to one of claims 1 to 3, characterized in that the signal line of the pressure-limiting valve (19) is at least temporarily connected to either the supply line (3) or the return line (4) within a limited area of the piston path, whereby preferably a signal line is arranged that is connected to the central compartment of the working cylinder and that is uncovered by the hammer piston (13) in direction of the advance stroke to a certain extent once the predetermined impact plane (TAE) has been passed and that is then at least temporarily connected with the reverse stroke (4), that is leading to the central compartment of the working cylinder that is covered by the hammer piston (13) in direction of the advance stroke once the predetermined impact area (TAE) has been passed, which is connected to an at least temporary disconnection of the connection between the signal line and a hammer line connected with the supply line (3).
5. Impact device according to one of claims 3 or 4, characterized in that after achieving the pressure level required for the deactivation, the pressure level in the signal line to the pressure-limiting valve (19) is maintained by means of an auxiliary valve and/or a throttle at least until the hammer piston (13) is moved out of the hydraulic stop buffer during the return stroke or, maximally, until the hammer piston (13) triggers a signal during the return stroke for changing the position of a control valve into the advance stroke position.
6. Impact device according to one of claims 1 to 5, characterized in that the pressure-limiting valve (19) can be controlled via a stoke length reversal bore (HU) and/or that in the line between the central compartment of the working cylinder and the spool valve, in which the signal for changing the setting of the control valve depending on the position of the piston is due, a shutoff valve is provided with the supply line or the return line depending on the pressure acting in the section of the line positioned on the side of the central compartment of the working cylinder, the pressure-limiting valve (19) being provided between the shutoff valve and the spool valve (15).
7. Impact device according to one of claims 1 to 6, characterized in that in the line between the central compartment of the working cylinder and the spool valve, in which the signal for changing the setting of the spool valve depending on the position of the piston applies, a shutoff valve is provided connecting the section of the line on the side of the spool valve with the supply line or the return line depending the pressure prevailing in the section of the line positioned on the side of the central compartment of the working cylinder, the pressure-limiting valve (19) being provided between the central compartment of the working cylinder and the shutoff valve:
8. Impact device according to one of claims 1 to 7, characterized in that bore holes with lines are provided in the central compartment of the working cylinder that are provided such that the piston uncovers a throttled connection between a line connected with the supply line (3) and a line connected with the return once the hammer piston has passed its top or bottom dead end to a certain extent.
9. Impact device according to one of claims 1 to 8, characterized in that the control valve, preferably the pressure-limiting valve (19) is provided with a control area that after the actuation in the shut-off position is connected to the pressure level, such that an additional operation force is effective in shut-off position.
10. Impact device according to one of claims 1 to 3, characterized in that a pressure-relief valve (39) is also provided between the supply line (3) and the return line (4).

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