Impact piston device for an impact drill

Description

[0001] The invention relates to a percussion piston device for a percussion drill drive, comprising a percussion piston which is reversibly mounted in a piston housing between a front impact position and a rear retraction position, wherein the percussion piston has at least one front pressure-bearing surface and at least one rear pressure-bearing surface, wherein together with the piston housing at least one front pressure chamber and one rear pressure chamber are formed, a hydraulic fluid supply, a hydraulic fluid discharge, a first control device by which at least the rear pressure chamber is alternately connected to the hydraulic fluid supply and the hydraulic fluid discharge to effect a reversing movement of the percussion piston, and a second control device by which at least one stroke of the percussion piston within the piston housing is adjustable.wherein the first control device comprises a controllable first control valve and the second control device comprises a controllable second control valve, according to the preamble of claim 1.

[0002] These types of impact piston devices are used particularly in impact drill drives, which are required for earth and rock drilling machines, especially for so-called anchor drilling rigs. With an impact piston, an additional percussive movement can be applied to a rotating drill bit. This results in good drilling progress, especially when drilling hard materials, particularly rock or stone.

[0003] A generic impact piston device for an impact drill drive is shown, for example, in DE 26 35 191 C3.

[0004] This known impact piston device comprises a piston or hammer which is axially movable within a piston housing between a front pressure chamber and a rear pressure chamber. A first control device with a control valve continuously pre-charges one of the two pressure chambers with hydraulic fluid. The other pressure chamber is alternately supplied with and emptied of pressure fluid by the first control device with the control valve. When fluid is supplied to this pressure chamber, the larger pressurized area of ​​the impact piston causes an axial displacement in the opposite direction to the pre-charged pressure. A corresponding counter-movement occurs when the pressure chamber is emptied or vented.

[0005] To change the stroke length of the impact piston, a second control device with a control valve is arranged, which is separate from the first control device. Different stroke lengths of the impact piston or hammer can be set by opening and closing various provided channels and axially offset annular grooves to the piston housing.

[0006] The adjustments are subject to a certain time delay.

[0007] Another generic device according to the preamble of claim 1 is shown in JP H10 80878 A.

[0008] The invention is based on the Aufgabe The basis is to specify a piston device which has a particularly efficient response behavior.

[0009] The problem is solved according to the invention by a piston-type device with the features of claim 1. Preferred embodiments of the invention are specified in the dependent claims.

[0010] The impact piston device according to the invention for an impact drill drive is characterized in that the first control valve and second control valve are arranged in a common valve housing.

[0011] A fundamental aspect of the invention is to combine the two control valves of the two control devices in a single valve housing. This results in significantly shorter lines and channels for the hydraulic fluid. Furthermore, the lines within the housing can be precisely defined, thus avoiding or largely reducing the risk of leaks and damage to exposed pipes or hoses. The shortened lines and the resulting improved flow, along with a corresponding reduction in the fluid volume within the lines, further enhance the overall efficiency.

[0012] The response behavior of the control arrangement with the two control valves has been improved. This allows for faster and more efficient control and adjustment of the impact piston during operation, while also resulting in a more compact and robust design.

[0013] According to the invention, the valve housing comprises a valve block in which the fluid lines and valve receptacles are formed, in particular milled. This results in a particularly robust valve and control arrangement within a preferably metallic valve block. This block is particularly insensitive to vibrations and external mechanical influences.

[0014] According to the invention, the lines are inserted into the valve block as recesses, in particular by milling. A cover plate is also provided, which seals the valve block with the valve lines and the valve receptacles. The cover plate is placed on the valve block by means of a suitable seal and preferably screwed to it in a liquid-tight manner. This preferably two-part housing design allows, on the one hand, for particularly simple manufacturing of a robust valve block and, on the other hand, enables simple maintenance, whereby only the cover plate or upper housing half needs to be removed from the valve block or a lower housing half.

[0015] A particularly advantageous embodiment of the invention consists in the valve housing being provided with a connection for the hydraulic fluid supply, a connection for the hydraulic fluid discharge, and a connection to a pipe connection with the piston housing. In particular, only these three, four, or five connections can be provided on the housing, thus enabling a particularly robust device.

[0016] In principle, any suitable and required control valve can be provided and arranged within the valve block. It is particularly preferred that the first control valve be designed as a controllable 3 / 2-way valve. The control valve can preferably be actuated by an electrically actuated, in particular an electromagnetic, actuator. The control valve can, in particular, have an axially displaceable control piston, which can be moved between its actuation positions by means of an electromagnet.

[0017] A particularly advantageous embodiment of the invention lies in the fact that the first control valve alternately connects the piston housing, especially the rear pressure chamber, to the hydraulic supply and the hydraulic discharge. In particular, a front pressure chamber, which is located closer to the piston's striking surface, can be continuously supplied with a constant hydraulic fluid pressure. By alternately connecting the rear pressure chamber via the first control valve to the hydraulic supply on the one hand and the hydraulic discharge on the other, a reversing movement of the striking piston can be effected by means of a corresponding design of annular actuating surfaces on the striking piston.

[0018] By increasing the actuation area of ​​the piston facing the rear pressure chamber, a significantly greater force can be exerted on the piston in the rear pressure chamber when the hydraulic supply is activated, compared to the force exerted on the correspondingly smaller actuation area of ​​the piston in the front pressure chamber. The hydraulic supply can be designed with an annular groove on the piston and / or the piston housing, allowing pressurized fluid to flow from the front pressure chamber to the rear pressure chamber via a pressure channel at a specific piston position, thus initiating the impact action.The resulting equal pressure in both pressure chambers, due to the different sizes of the actuation surfaces, leads to a greater force being exerted by the pressure fluid on the piston in the rear pressure chamber, thus pushing it forward in a defined manner to deliver a blow.

[0019] According to a further embodiment of the invention, it is preferred that the controllable second control valve is designed as a 3 / 2-way valve or as a 4 / 3-way valve. Similar to the first control valve, the second control valve can be electrically actuated by an electromagnetic actuator. In particular, the control valve can have an axially displaceable control piston, which can be moved between its actuating positions by means of an electromagnet. Alternatively, the control valves can also be actuated via pressure channels.

[0020] A particularly advantageous embodiment of the piston-type device according to the invention consists in that an outlet of the second control valve is connected to a control line for actuating the first control valve. A direct control line can thus be provided between the two control valves. A change in pressure can trigger a control action.

[0021] According to a further embodiment of the invention, the inlets of the second control valve are each connected to an annular space in the piston housing. The annular space in the piston housing can be formed by an annular groove on the piston itself and / or in the inner wall of the piston housing. In particular, several axially spaced annular spaces are provided for adjusting the stroke length of the piston. Depending on the configuration of the annular spaces, it is thus possible to determine at which axial position of the piston a pressure channel and pressure build-up are achieved in the rear pressure chamber, thereby initiating a forward impact movement of the piston.

[0022] In a further embodiment of the piston device according to the invention, it is preferred that a control port for actuating the second control valve is provided on the valve housing. This allows direct actuating of the second control valve via a control port.

[0023] The invention comprises a percussion drill drive with at least one drill drive, wherein a percussion piston device according to the invention is provided. The drill drive is designed to drive a drill bit by rotating it. An axial percussive movement can be exerted on the drill bit continuously or at specific times via the percussion piston device.

[0024] In particular, according to the invention, the impact drill drive can be arranged on a carriage or mast of an earth or rock drilling machine. The earth or rock drilling machine can be used, in particular, for anchor drilling in specialist foundation engineering.

[0025] The invention is further described below with reference to a preferred embodiment, which is shown schematically in the figures. The figures show: Fig. 1 a schematic circuit arrangement for the impact piston device according to the invention; Fig. 2 a hydraulic circuit diagram for the impact piston device according to the invention, and Fig. 3 a block-like valve housing provided for the invention in various side views and various perspective views.

[0026] To illustrate the functioning of a piston device 10 according to the invention, a first circuit arrangement with a first control unit 50, but without the second control unit according to the invention, is shown. Fig. 1 The diagram shows a shaft-shaped impact piston 20 being mounted in a piston housing 12, which is only schematically indicated, so as to be reversibly movable. The impact piston 20 projects from the piston housing 12 with a front striking face 22, which can act upon, for example, a drill drive shaft (not shown).

[0027] The piston 20 has a front first shoulder 24 and at least one further rear second shoulder 28 formed in a generally known manner. The shoulders 24, 28, which have larger diameters, are axially spaced apart from each other, with an annular space 15 of smaller diameter formed between each pair of adjacent shoulders 24, 28. The first shoulder 24 defines a first front pressure chamber 14 in the piston housing 12 with a cylindrical receiving chamber, and a front pressure-applying surface 26, directed towards the front pressure chamber 14, is formed on the first shoulder 24.

[0028] In the receiving chamber of the piston housing 12, a rear pressure chamber 16 is formed behind the second shoulder 28, wherein a rear pressure-applying surface 29, directed towards the rear pressure chamber 16, is formed on the rear second shoulder 28. It is essential for the functioning of this piston device 10 that the rear pressure-applying surface 29 is larger than the front pressure-applying surface 26, as can also be clearly seen in Fig. 1 is shown.

[0029] For reversing the movement of the piston 20, which is located in Fig. 1 In a retracted position within the piston housing 12, a hydraulic supply 30 with lines is provided. Hydraulic fluid is drawn from a tank 42 via a hydraulic pump 32 and introduced under pressure into the hydraulic supply 30. A first branch to the front pressure chamber 14 continuously supplies this chamber with pressurized hydraulic fluid. The action of the hydraulic fluid in the front pressure chamber 14 on the front pressurizing surface 26 causes the impact piston 20 to move rearward into its retracted position. Fig. 1 The depicted retreat position was pressed.

[0030] Furthermore, the hydraulic supply 30 extends via a line to a first control unit 50 with a first control valve 52, which has three ports and can assume two valve positions. The first control valve 52 is therefore a 3 / 2-way valve.

[0031] In the Fig. 1 In the first position shown, hydraulic fluid is directed from the hydraulic supply 30 to the rear pressure chamber 16 in the piston housing 12. Due to the larger area of ​​the rear pressurization surface 29 at the second shoulder 28, a force is exerted on the impact piston 20 in the direction of the impact side 22, which is greater than the counterforce exerted by the pressurization fluid in the front pressure chamber 14 on the front pressurization surface 26. In this position of the first control valve 52, the impact piston 20 is thus moved forward out of the piston housing 12 to execute an impact movement. A first control port 54 on the controllable first control valve 52 allows the valve position to be detected depending on the pressure in the hydraulic supply 30 upstream of the first control valve 52.A second control connection 56 allows pressure to be detected in the control line 57, which leads into the piston housing 12 at the edge of the front pressure chamber 14 towards the first paragraph 24.

[0032] By moving the piston 20 forward towards the impact side 22, the control line 57 is disconnected from the front pressure chamber 14. With a further movement of the piston 20 towards the Fig. 1 In the direction of the arrow, the annular space 15 connects to a vent line 59, which also opens into the piston housing 12. When the piston 20 is in a corresponding position, the annular space 15 can vent through the vent line 59 to a hydraulic outlet 40 and thus to the tank 42. The annular space 15 is therefore depressurized or at least has a reduced pressure. As the piston 20 is moved further in the direction of the arrow, the vented annular space 15 connects to the control line 57, resulting in a corresponding pressure reduction in the control line 57. This allows the first control valve 52 to be switched via the second control port 56 of the first control unit 50.

[0033] During this changeover, the control valve 52 assumes its second valve position, in which no further pressure fluid is directed to the piston housing 12 via the hydraulic supply 30 and the first control valve 52. Furthermore, the connecting line to the piston housing 12 is now connected to the hydraulic outlet 40 and thus to the tank 42 via the first control valve. This vents the rear pressure chamber 16 to the tank 42 and depressurizes it, or at least causes a noticeable pressure drop. Consequently, the pressure in the front pressure chamber 14 is higher due to the continuous supply of hydraulic fluid via the hydraulic supply 30 through the first branch, and thus the force exerted on the front pressure-applying surface 26, acting on the impact piston 20, is also greater. This causes the impact piston 20 to retract back into the piston housing 12 into its retraction position. Fig. 1 initiated.

[0034] From the arrangement according to Fig. 1 It follows that the arrangement of one or more annular spaces 15 has an influence on the stroke length of the impact piston 20 in the piston housing 12.

[0035] When two or more annular spaces 15 are arranged on the piston 20, a second control device 60, which is connected to Fig. 2 It is explained that an influence and thus an adjustment of the stroke of the impact piston 20 can be set.

[0036] According to the invention, the first control device 50 and the second control device 60 are arranged in a common valve housing 70, the circuit arrangement being shown schematically in Fig. 2 is shown and explained below.

[0037] As in connection with Fig. 1 As shown, the first control device 50 can have a first actuating valve 52 with three ports and two valve positions. A connection P is made to the hydraulic supply 30, while a connection T is made to the hydraulic outlet 40 and thus to a tank 42. The first actuating device 50 is connected to the piston housing 12 of the impact piston 20 via a connection S, as previously described in connection with Fig. 1 described. The first control connection 54 of the first control unit 50 is to be used in accordance with the preceding description. Fig. 1 connected to the hydraulic supply line 30.

[0038] According to the invention, the second control device 60 with the second control valve 62 is also arranged in the same valve housing 70 in which the first control device 50 is arranged.

[0039] The second control valve 62 shows in the illustration according to Fig. 2 preferably has four ports and three valve positions, thus it is a 4 / 3-way valve. One outlet 64 of the second control valve 62 is connected via a pressure control line 65 to the second control port 56 of the first control valve 52. The three annular spaces (not shown) of a possible additional impact piston 20 with four steps are connected to each of the three inlets HB1, HB2, and HB3 of the second control valve 62. Via a control port 66 on the second control valve 62 and a control line 68, a machine operator can select, according to a desired stroke length of the impact piston 20 in the piston housing 12, which of the inlets HB1, HB2, HB3, and thus which of the annular spaces 15 on the impact piston 20, is to be connected to the pressure control line 65 to actuate the first control valve 52.Depending on the arrangement of the three annular spaces in the present embodiment, the stroke of the impact piston 20 in the piston housing 12 will then be longer or shorter.

[0040] In principle, fewer or more annular spaces 15 can also be provided on the piston 20, whereby a corresponding adjustment of the second control valve 62 with a corresponding reduction or increase of the inlets must then be made.

[0041] The valve housing 70 provided for the invention, with a box-like valve block 72 which can be closed on one side by means of a cover plate 74, is shown in a multitude of views from different sides in Fig. 3 The cover plate 74 is shown only in the middle side view. Valve receptacles 76 and lines or line channels for forming the first control unit 50 and the second control unit 60 can be integrated into the valve block 72, in particular by milling. Overall, this results in a particularly robust circuit arrangement with short line paths. This allows for particularly fast actuation and switching to different stroke lengths.

[0042] Again Fig. 3 As can be seen, a connection for the hydraulic supply 30 can be located on one side of the valve housing 70, and a connection for the hydraulic outlet 40 and the control line 68 can be located on the opposite side. On another side, corresponding connections for the connection to the annular spaces for stroke limitation HB can be arranged.

Claims

1. Impact piston device for a percussion drill, having - an impact piston (20) which is mounted so as to be movable in a reversing manner in a piston housing (12) between a front impact position and a rear retraction position, wherein the impact piston (20) has at least one front pressure-application surface (26) and at least one rear pressure-application surface (29), wherein, together with the piston housing (12), at least one front pressure chamber (14) and one rear pressure chamber (16) are formed, - a hydraulic fluid supply (30), - a hydraulic fluid discharge (40), - a first control device (50), by means of which at least the rear pressure chamber (16) is connected alternately to the hydraulic fluid supply (30) and to the hydraulic fluid discharge (40) for effecting the reversing movement of the impact piston (20), and - a second control device (60), by means of which at least a stroke path of the impact piston (20) within the piston housing (12) is adjustable, - wherein the first control device (50) has an actuatable first control valve (52) and the second control device (60) has an actuatable second control valve (62) and - wherein the first control valve (52) and the second control valve (62) are arranged in a common valve housing (70), characterized in that the valve housing (70) comprises a valve block (72) in which the fluid lines and valve receptacles (76) are formed, in particular milled, and that a cover plate (74) is provided, with which the valve block (72) is closed with the fluid lines and the valve receptacles (76).

2. Impact piston device according to claim 1, characterized in that a connection (P) for the hydraulic fluid supply (30), a connection (T) for the hydraulic fluid discharge (40) and a connecting port (S) for a line connection with the piston housing (12) are arranged on the valve housing (70).

3. Impact piston device according to any one of claims 1 to 2, characterized in that the first control valve (52) is designed as an actuatable 3 / 2 directional valve.

4. Impact piston device according to any one of claims 1 to 3, characterized in that the first control valve (52) connects the piston housing (12), in particular the rear pressure chamber (16), alternately to the hydraulic fluid supply (30) and to the hydraulic fluid discharge (40).

5. Impact piston device according to any one of claims 1 to 4, characterized in that the actuatable second control valve (62) is configured as a 3 / 2 directional valve or as a 4 / 3 directional valve.

6. Impact piston device according to any one of claims 1 to 5, characterized in that an output (64) of the second control valve (62) is connected to a pressure control line (65) for actuating the first control valve (52).

7. Impact piston device according to any one of claims 1 to 6, characterized in that inputs of the second control valve (62) are each connected by a line to an annular space (15) in the piston housing (12).

8. Impact piston device according to any one of claims 1 to 7, characterized in that a control port (66) for actuating the second control valve (62) is provided on the valve housing (70).

9. Percussion drill having at least one drilling drive, characterized in that an impact piston device (10) according to any one of claims 1 to 8 is provided.