Percussion boring device and method for reversing a percussion boring device

Abstract

A percussion boring device comprising a casing, a guide tube fixed to the casing, and a control bushing axially displaceable on the guide tube. An impact piston of the device is axially displaceable on the control bushing and configured to be actuated in a reciprocating manner within the casing such that in a first switching position the impact piston strikes a front impact surface to actuate the percussion boring device in a first movement direction, and in a second switching position a rear impact surface to actuate the percussion boring device in a second movement direction. A pressure increasing means is provided and configured to generate a pressure for reversing the percussion bore device, wherein the generated pressure is higher than a pressure for moving the impact piston. The guide tube and the control bushing are configured to reverse movement directions of the impact piston.

Claims

1. A percussion boring device comprising: a casing; a guide tube fixed to the casing; an impact piston configured to be actuated in a reciprocating manner within the casing by application of an operating pressure; a control bushing axially displaceable on the guide tube to (i) a first switching position to actuate the percussion boring device in a first movement direction in which the impact piston strikes a front impact surface, and to (ii) a second switching position to actuate the percussion boring device in a second movement direction in which the impact piston strikes a rear impact surface, wherein the impact piston is axially displaceable on the control bushing; a control pressure source fluidly coupled to the control bushing and configured to generate a high fluid pressure for axially displacing the control bushing to the first switching position to actuate the percussion boring device in the first movement direction, the high fluid pressure generated being higher than the operating pressure for moving the impact piston in the reciprocating manner in the first movement direction and the second movement direction, and a control valve configured to cause a pressure in a control pressure line to be reduced below the operating pressure to cause the operating pressure to displace the control bushing to the second switching position to actuate the percussion boring device in the second movement direction; wherein, while the high fluid pressure for axially displacing the control bushing to the first switching position is applied to the control bushing, the control bushing is in the first switching position and the impact piston is configured to be moved by the operating pressure in the first movement direction; wherein, while a pressure less than the operating pressure is applied to the control bushing, and the operating pressure is provided to the impact piston, the control bushing is in the second switching position and the impact piston is configured to be actuated by the operating pressure in the reciprocating manner in the second movement direction.

2. The percussion boring device according to claim 1, wherein an annular space is formed between the guide tube and an annular element, wherein the annular space is at least partially covered by the control bushing, and wherein the annular space is connected to a control line configured to receive the high fluid pressure generated by the control pressure source for axially displacing the control bushing to the first switching position to actuate the percussion boring device in the first movement direction.

3. The percussion boring device according to claim 1, wherein, for axially displacing the control bushing to the first switching position to actuate the percussion boring device in the first movement direction, the high fluid pressure generated by the control pressure source is 5 to 25 bar.

4. The percussion boring device according to claim 1, wherein the control valve comprises a multi-position directional control valve which includes at least one position configured to apply the high fluid pressure generated by the control pressure source to the control bushing for axially displacing the control bushing to the first switching position to actuate the percussion boring device in the first movement direction and a second position configured to vent the control pressure line to cause the operating pressure to displace the control bushing to the second switching position to actuate the percussion boring device in the second movement direction.

5. The percussion boring device according to claim 1, further comprising a pressure reducing valve, wherein the control pressure source is connected to the impact piston and the pressure reducing valve is connected between the control pressure source and the impact piston.

6. The percussion boring device according to claim 1, wherein operation of the percussion boring device in the first movement direction is based upon applying the high fluid pressure from the control pressure source to axially displace the control bushing to the first switching position for movement in the first movement direction; and application of the operating pressure to the impact piston for actuation of the impact piston in the reciprocating manner within the casing of the percussion boring device in the first movement direction.

7. A percussion boring device comprising: a casing; a guide tube fixed to the casing; an impact piston configured to be actuated in a reciprocating manner within the casing; a control bushing axially displaceable on the guide tube to (i) a first switching position to actuate the percussion boring device in a first movement direction in which the impact piston strikes a front impact surface, and to (ii) a second switching position to actuate the percussion boring device in a second movement direction in which the impact piston to strike a rear impact surface, wherein the impact piston is also axially displaceable on the control bushing; a control line operatively coupled to the control bushing, and a control valve; a control pressure source, in fluid communication with the control valve, operative to generate a high fluid pressure for axially displacing the control bushing to the first switching position for movement of the percussion boring device in the first movement direction, the high fluid pressure generated by the control pressure source being higher than an operating pressure for actuating the impact piston in the reciprocating manner in the first movement direction and the second movement direction; and wherein the control valve in a first position is operative to apply a pressure lower than the operating pressure to the control bushing to place the control bushing in the second switching position for movement of the percussion boring device in the second movement direction, and wherein the control valve in a second position is operative to apply the high fluid pressure from the control pressure source to place the control bushing in the first switching position for movement of the percussion boring device in the first movement direction.

8. The percussion boring device according to claim 7, wherein an annular space formed between the guide tube and an annular element, wherein the annular space is at least partially covered by the control bushing, and wherein the annular space is connected to the control line and is configured to receive the high fluid pressure for axially displacing the control bushing to the first switching position for movement of the percussion boring device in the first movement direction.

9. The percussion boring device according to claim 7, wherein, for axially displacing the control bushing to the first switching position to actuate the percussion boring device in the first movement direction, the high fluid pressure generated by the control pressure source is 5 to 25 bar.

10. The percussion boring device according to claim 7, wherein operation of the percussion boring device in the first movement direction is based upon application of the high fluid pressure from the control pressure source to axially displace the control bushing to the first switching position for operation in the first movement direction, and application of the operating pressure to the impact piston for movement of the percussion boring device in the first movement direction.

11. A method for operating a percussion boring device including an impact piston in a forward movement direction and a reverse movement direction, the forward movement direction configured to strike a front impact surface to actuate the percussion boring device and the reverse movement direction configured to strike a rear impact surface to actuate the percussion boring device, and a control bushing axially displaceable on a guide tube for switching a movement direction of the impact piston, responsive to movement of the control bushing, comprising: applying an operating pressure to the impact piston to actuate the impact piston in a reciprocating manner within a casing in one of the forward movement direction and the reverse movement direction; applying, by a control pressure source operatively coupled with the control bushing, one of a first fluid pressure and a second fluid pressure for axially displacing the control bushing on the guide tube and bringing the control bushing into one of (i) a first switching position in which the impact piston strikes the front impact surface to actuate the percussion boring device in the forward movement direction by application of the first fluid pressure and (ii) a second switching position in which the impact piston strikes the rear impact surface to actuate the percussion boring device in the reverse movement direction by application of the second fluid pressure, wherein application of the first fluid pressure is selected via a control valve with a selectable position configured to cause a fluid pressure in a control pressure line to be increased above the operating pressure to cause the operating pressure to displace the control bushing to the first switching position to actuate the percussion boring device in the forward movement direction; wherein the second fluid pressure is lower than an operating pressure for moving the impact piston in the forward movement direction and the second movement direction.

12. The method of claim 11, wherein applying the one of the first fluid pressure and the second fluid pressure for axially displacing the control bushing comprises applying the one of the first fluid pressure and the second fluid pressure to an annular space configured for receiving the one of the first fluid pressure and the second fluid pressure, the annular space formed between the guide tube and an annular element at least partially covered by the control bushing.

13. The method of claim 11, wherein applying the first fluid pressure by the control pressure source further comprises selecting a position of a multi-position directional control valve operatively coupled to the control pressure source and the control bushing to apply the first fluid pressure to the control bushing to bring the control bushing into the first switching position to actuate the percussion boring device in the forward movement direction.

14. The method of claim 11, wherein operation of the percussion boring device in the forward movement direction is based upon applying the fluid pressure higher than the operating pressure used for moving the impact piston from the control pressure source to axially displace the control bushing to the first switching position for movement in the forward movement direction; and application of the operating pressure to the impact piston for actuation of the impact piston in the reciprocating manner within the casing of the percussion boring device in the forward movement direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above statements, just as the following description of exemplary embodiments, do not constitute a relinquishment of specific embodiments of features.

(2) The invention is explained in greater detail below based on an exemplary embodiment shown in the drawings.

(3) In the drawings:

(4) FIG. 1 shows partial sectional view of a percussion boring device;

(5) FIG. 2 shows an enlarged view of the percussion boring device of FIG. 1 with extended control tube; and

(6) FIG. 3 shows the view in accordance with FIG. 2 with retracted control tube.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(7) FIG. 1 shows a percussion boring device 1 for drilling into the ground. An end of the percussion boring device 1, FIG. 1 on the left shows a drilling head having a drill bit. The percussion boring device 1 has an impact piston 2 mounted within a casing 3. The impact piston 2 can be actuated for a cyclical reciprocation in the casing 3. In a first switching position, the impact piston 2 strikes a front impact surface 30, shown in FIG. 2, to actuate the percussion boring device 1 in a first movement direction (in the embodiment shown in FIG. 1 to the left). In a second switching position the impact piston 2 strikes a rear impact surface 35, shown in FIG. 2, to actuate the percussion boring device in a second movement direction (in the embodiment shown in FIG. 1 to the right).

(8) To provide the pressure for reversing the direction of the impact piston 2, a pressure increasing means 20 is provided in the form of a pressure booster, which can be used to provide the pressure required for the reversal, in particular for extending the control bushing 4 relative to the guide tube 5. In relation to the feed, a directional control valve 21 is installed downstream of the pressure increasing means 20, which can be used in one position to bring the control bushing 4 into a switching position to increase pressure, and in another position to bring the control bushing 4 in a different switching position to decrease pressure.

(9) For switching the movement directions, the percussion boring device 1 has a guide tube 5 fixed to the casing and a control bushing 4 axially displaceable on the guide tube 5. The impact piston 2 can be axially displaceable on the control bushing 4. In particular from FIG. 2 it can be gathered that the control bushing 4 temporarily engages with the impact piston 2 at the axial displacement.

(10) The control bushing 4 has two sections 7, 8 that are configured as a head section 7 and the main body section 8, connected with each other by means of a movable connection. In exemplary embodiment illustrated in FIGS. 1 to 3, the movable connection 6 is designed as an elastic connecting section, which is configured to enable the two sections of the control bushing 4 to pivot relative to each other. The movable connection 6 is connected to the main body section 8 and the head section 7 encompasses the elastic connecting section.

(11) The main body section 8 of the control bushing 4 abuts at least in part the guide tube 5. The head section 7 of the control bushing 4 is on the inside spaced apart from the guide tube 5. The inner diameter of the head section 7 of the control bushing 4 is, in particular at the position spaced from the main body section 8 end, larger than the outer diameter of the guide tube 5. On the end of the head section 7 adjacent the main body section 8, the head section 7 has a smaller inner diameter than at the end of the head section 7 spaced apart from the main body section 8.

(12) A stop ring 12 having a stop for the control bushing 4 is connected to the guide tube 5. To this end, at the head section 7 of the control bushing 4 a counter element is configured corresponding to the stop, which abuts the stop of the guide tube 5 in the switching position of the control bushing 4 to the guide tube 5 shown in FIG. 2. The stop ring 12 can, with the outer circumference, be an inner guide for the head section 7 of the control bushing 4.

(13) In FIG. 2 an annular space 10 is shown, which is formed between the guide tube 5 and an annular element 9, which is disposed fixed to the guide tube 5. The annular space 10 is at least partially frontally delimited by the control bushing 4 and is connected to a control line 11 to which a fluid pressure can be applied. Pressure can be applied to the annular space 10 by means of the control line 11 to extract the control bushing 4 out of the annular space 10. If the pressurization of the annular space 10 is terminated, the operating pressure present at the control bushing 4 effects a retraction or a resetting of the control bushing 4.

(14) FIG. 3 shows by way of example also for FIG. 2 a vent hole 13, which is formed in the head section 7 of the control bushing 4 to achieve a pressure balance.