Impact pulse or vibration generator for construction machinery

Abstract

To achieve more efficient striking or vibration behavior.SOLUTION: The invention relates to a device and a method for generating striking pulses or vibrations for a construction machine, which are accompanied with: a housing; a piston which is reversibly reciprocable in a working space in the housing between a first reversal point and a second reversal point; a pressure fluid supply section, through which pressure fluid can be led to the inside and the outside of the working space near the first reversal point and the second reversal point, thereby the piston can be set into reversible movement to generate the striking pulses or the vibrations; at least one controllable valve, through which the pressure fluid can be led to the inside and / or the outside of the working space; and a control unit which is connected to the at least one controllable valve, and which can control and change the movement of the piston in the working space. According to the invention, provision is made in that the control unit is designed to move the piston at a frequency that corresponds to a resonance frequency of an overall arrangement comprising the piston and the pressure fluid.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a device for generating striking pulses or vibrations for a construction machine according to the preamble of claim 1, comprising a housing, a piston capable of reciprocating in a working space in the housing between a first reversal point and a second reversal point, a pressurized fluid supply through which pressurized fluid can be introduced into and out of the working space near the first reversal point and the second reversal point, respectively, thereby generating striking pulses or vibrations by bringing the piston into a reversing motion, at least one controllable valve through which pressurized fluid can be introduced into and / or out of the working space, and a control unit connected to the at least one controllable valve and capable of controlling and varying the piston movement in the working space.

[0002] The present invention further relates to a method for generating impact pulses or vibrations for a construction machine according to the preamble of claim 11, comprising reciprocating a piston in a working space in a housing between a first reversal point and a second reversal point, bringing the piston into a reversing motion by a pressurized fluid to generate the impact pulses or vibrations, directing the pressurized fluid into and out of the working space near the first reversal point and the second reversal point, controlling by a control unit at least one controllable valve through which the pressurized fluid is directed into and / or out of the working space, and controlling the movement of the piston by the control unit. [Background technology]

[0003] A typical vibration generator is shown in the patent document EP 1 239 636. In this known vibration generator, the working space in the housing is divided into two pressure chambers by a working piston. By selectively supplying and releasing the pressurized fluid to and from the two pressure chambers in an alternating manner via inlets and outlets, the working piston can be moved in a counter-rotating manner to generate vibrations. The timely supply and release of the pressurized fluid to the individual pressure chambers is achieved by means of controllable valves and a complex arrangement of ducts in the housing. Furthermore, by means of measuring means arranged inside the working piston, a precise determination of the position of the working piston in the working space and thus relative to the housing is carried out. By means of control means, in addition to the opening and / or closing times of the controllable valves, further parameters of the pressurized fluid supply can be set. By varying these parameters, it is possible, inter alia, to vary both the frequency and the stroke of the working piston in the housing. Various parameters can be stored in the program memory which cause selective activation of the vibration generator, so that a frequency and stroke length optimally adapted to the operating application can be selected for the vibration generator. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] European Patent Application Publication No. 3417951 (A1) [Patent Document 2] GB Patent Application Publication No. 920158(A) [Patent Document 3] U.S. Patent No. 4,026,193 (A) [Patent Document 4] U.S. Patent No. 4,031,812 (A) Summary of the Invention [Problem to be solved by the invention]

[0005] The known vibration generators allow the frequency and stroke to be varied within a limited range, and thus the vibration parameters to be set to suit the application. However, for the general identification of the vibration parameters and for the setting of the vibration system, the mass of the vibrating piston is mainly used. A suitable frequency is estimated based on, inter alia, the piston mass.

[0006] Further mechanical control means in the vibration generator can be cited, for example, from US Pat. No. 5,399,633, US Pat. No. 5,499,623 or US Pat. No. 5,499,633. All these known devices have an operating piston and a control piston which open or close certain ducts according to their respective positions in the housing, moving the operating piston by causing selective alternating supply to two pressure chambers on either side of it.

[0007] The production of this type of device is time-consuming and cost-intensive. Moreover, due to the duct layout, a certain vibration or impact behavior of the piston is predefined at a given pressure level. Changes in vibration frequency and impact energy can only be made within a very limited range, and in some cases laborious mechanical reworking is required.

[0008] The object underlying the present invention is to provide an impact pulse or vibration generating device and method with which a particularly efficient impact or vibration behavior can be achieved. [Means for solving the problem]

[0009] This object is achieved on the one hand by a device having the features of claim 1 and on the other hand by a method having the features of claim 11. Preferred embodiments of the invention are declared in the dependent claims.

[0010] A feature of the device according to the invention is that the control unit is designed to move the piston at a frequency that corresponds to the resonant frequency of the entire arrangement including the piston and the pressurized fluid. According to the present invention, the striking pulse and / or the entire arrangement of the vibration generator is not only determined by the properties of the piston, such as its diameter and mass, but also to a decisive extent by further parameters that influence the pressurized fluid, such as the generated pressure, its line cross section, line length, line shape and surface, as well as the switching times and shapes of the valve slide and its control edges and the valve slide arrangement in the housing of the control valve. These further parameters can have a decisive influence on the resonant frequency and the associated piston stroke and thus on the force transmitted by the device according to the invention or on the striking pulse transmitted.

[0011] The basic idea of ​​the invention is that the improvement of the variably possible drive of the piston, i.e. of the vibration and / or impact pulse generator, allows for example an improvement of the penetration of the tool attached to the vibration and impact pulse generator into different soils, etc., by pressurizing it with a pressurized fluid with parameters adapted to the system and the desired application. By identifying the resonance parameters of the entire arrangement, including the piston and the pressurized fluid, it is possible, on the one hand, to identify the appropriate resonance frequency and resonance stroke, and, on the other hand, the variable drive of the vibration generator also allows a dynamic adaptation of the parameters during operation to adapt to changes in the process. For example, in earth drilling methods, such changes may be caused by changes in the soil or rock formations to be penetrated. In addition, various concomitant conditions, such as wear and tear, ageing, changes in temperature and viscosity of the pressurized fluid, etc., may also affect the resonance frequency.

[0012] Thus, in the device according to the invention, the dynamic parameter adaptation thus made possible can be triggered in real time during operation, and due to the permanent detection of the actual vibration, the control circuit can ideally optimize the resonant frequency, thereby achieving an improved piston vibration and thus an increased force and / or pulse generation, resulting in a versatile vibration circuit that allows the device to be used extensively in construction machines.

[0013] In principle, any suitable controllable valve can be used in the device according to the invention. According to a further development of the invention, it can be particularly advantageous for the valve to be a solenoid valve. The valve body can be adjusted between an open and closed position by means of an electromagnetic arrangement. Intermediate positions can also be set so that the amount of pressurized fluid fed to the working space can be set. In principle, any type of pressurized fluid can be fed, but in this case it is preferable to use hydraulic oil.

[0014] A preferred embodiment variant of the invention consists in providing measuring means for determining the position of said piston in said working space, for which all sensors usable for length or position measurement can be employed, in particular all sensors operating in an optical, capacitive, inductive, magnetic or other manner.

[0015] According to one embodiment of the invention, the measuring means can advantageously comprise a linear sensor, which is particularly appropriate if the piston is moved linearly within the housing between the two reversal points.

[0016] Basically, the piston can be moved in a reversing motion in the housing such that the two front faces of the piston do not come into contact with the wall of the housing. This type of device can be used as a so-called vibration generator. A successful embodiment of the invention consists in arranging a striking surface on at least one of the reversing points, on which the piston strikes individually, thereby generating striking pulses. Basically, striking surfaces can be arranged on both the front face of the piston and the opposite front face of the piston on the housing. However, if desired, only one striking surface can be provided, in order to generate individual striking pulses, which are suitable for striking drilling, etc.

[0017] According to another preferred variant, the overall arrangement includes the housing, which allows further factors and parameters influencing the oscillating circuit to be represented, such as the cross-sectional area and roughness of the ducts leading the pressurized fluid into and out of the working space and possible elbow losses in these ducts within the housing.

[0018] According to a further variant of the invention, it is advantageously possible to set and adjust the frequency and / or stroke of the piston by means of the control unit. By varying the frequency, in particular the opening and closing times and, if appropriate, the supply of hydraulic energy can be set by the control unit. In addition, the piston stroke can be achieved by varying the positions of the two reversal points by opening and closing the controllable valves accordingly. With this aim in mind, it is advantageous to provide the control unit with an input interface, for example an input field. In addition, the control unit can also be operated directly via the usual machine control from an operating unit by an operator.

[0019] According to a further preferred embodiment of the present invention, the mass of the piston and / or the housing can be changed by installing or removing adjustment weights. In particular, when generating vibration or impact pulses in the device, changing the piston mass and / or cylinder mass will cause a large change in its resonant frequency. This means that the combination of the variable drive of the pressurized fluid by setting the piston reversal point and the matching piston or housing mass allows the system to cover a wide range of applications.

[0020] Another preferred embodiment variant of the invention can be found in the fact that various control programs for piston control can be stored in the program memory of the control unit. For example, application-specific control programs can be stored. For example, a high frequency and a small piston stroke can be presented at the beginning of the program, followed by a program sequence in which the piston stroke increases over time and the frequency decreases over time. Almost any number of different program sequences can be provided for controlling the piston in relation to frequency and stroke. For example, programs can be provided for a quick advance or a gentle drive process. In addition, programs for different soil types can be stored. The control unit can advantageously comprise an automatic program for resonant frequency determination. In that case, the individual response frequencies of the device are detected by a vibration sensor while the piston is driven through a frequency band starting from a start frequency and ending at a target frequency. The maximum of these response frequencies constitutes the resonant frequency.

[0021] According to the invention, a construction machine is also constructed, characterized in that the above-mentioned striking pulse or vibration generating device is arranged on it. In particular, a construction machine for foundation construction can be provided. However, the device can also be used in other construction machines with other tools, in particular those in which the penetration of the working edge or the material to be introduced into the ground is facilitated by the application of vibrations by a seismic mass. For example, this would be the case in the mining shovel of an excavator or in an attachment for an excavator.

[0022] According to an embodiment of the invention, the construction machine can be an earth drilling machine, which, if prepared for generating percussion pulses, can carry out percussion drilling, which is particularly advantageous when penetrating hard rock formations. Alternatively or additionally, the machine can also be designed to generate vibrations without percussion contact. Thus, in earth drilling machines in which the drilling tool is driven in a rotary manner, so-called overburden drilling can be carried out in particular, in which a vibration or oscillating movement is superimposed on the rotary movement of the drilling tool. The superimposed vibrations can result in a pseudo-liquefaction (quasi-liquefaction) of the ground, at least in the contact area with the drilling tool, which leads to an improvement of the drilling process.

[0023] Another embodiment of the invention can be found in the construction machine being a pile driver or vibrator, which can be used for example to introduce steel beams, piles or sheet piles by driving them into the ground with the action of percussion pulses and vibrations.

[0024] A feature of the method according to the present invention is that the at least one valve is controlled by the control unit to move the piston at a frequency corresponding to a resonant frequency of the entire array including the piston and the pressurized fluid.

[0025] This overall arrangement of the striking pulse and / or vibration generator not only represents the properties of the piston, such as its diameter and mass, but also has parameters that influence the vibration circuit, such as the applied pressure, the existing line cross-section, line length, line shape and surface, as well as the switching times and shapes of the valve slide and its control edges, and the valve slide arrangement in the housing of the control valve. These further parameters can have a decisive influence on the resonant frequency and the resulting piston stroke, and thus on the forces transmitted by the method according to the invention or on the striking pulses transmitted thereby.

[0026] According to a further development, it is advantageously provided that the position of the piston is detected by means of measuring means and the movement of the piston is controlled by the control unit in such a way that the control unit controls at least one controllable valve through which pressurized fluid is conducted into and / or out of the working space depending on the piston position detection.

[0027] The method according to the invention can be carried out in particular by means of the device described above, whereby the above-mentioned advantages are achieved.

[0028] The invention will be further described below by means of preferred embodiments which are illustrated diagrammatically in the accompanying drawings, in which: [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a schematic cross-sectional view of an apparatus according to the present invention. [Diagram 2] FIG. 2 is a circuit diagram of the device according to the present invention; [Diagram 3] 4 is a frequency diagram of the device according to the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] In Fig. 1, a principle diagram of a drill drive equipped with a vibration or impact pulse generator according to the invention is shown. All functional parts are provided in a housing 1 shown. A drill rod 2 projects from the housing, at the far end of which is a drill head 3 carried by the drill rod 2. The drill rod 2 is brought into a rotational movement about its axis by a hydraulic motor 4 and via a planetary gear 5. A drilling tool is arranged on the drill head 3. Due to the rotational movement of the drill head 3, a strip cut can be made in the borehole by means of a cutting edge of the drilling tool. The thickness of the cut depends on the force applied along the axial direction. To generate an alternating axial vibration force, a vibration generator 6, which substantially corresponds to the vibration or impact pulse generator according to the invention, is mounted on the planetary gear 5. The vibration generator 6 is supported in a rubber spring 7, by which the generated vibrations are isolated from the housing. The drill head 3, the drill rod 2, the planetary gear 5 and the hydraulic motor 4 together with the vibration / vibration generator 6 constitute the oscillating mass and thus the moving mass of the drill drive, for which purpose they are supported in an axial guide 11. Alternatively, the gear 5 can also be operated in such a way that it is decoupled from the vibration cell or vibration generator 6. In this case, the generated vibrations can be transmitted directly to the drill rod and thus to the drill head via a shaft that is guided through an output shaft, which is designed, for example, as a hollow shaft. The rotational movement generated in the gear can then also be transmitted from the hollow shaft to the drill rod and thus to the drill head via teeth or any tooth form that decouples the generated axial vibrations from the gear. Alternatively, the rotational movement can also be transmitted by the shaft and the generated vibrations by the hollow shaft.

[0031] For the generation of vibrations in the vibration generator 6, the latter comprises a vibration cylinder, more precisely a vibration piston 8, which is alternately pressurized by pressurized fluid in pressure chambers located on both sides of the vibration generator 6. This pressurized fluid is supplied through a pressurized fluid line P and is applied in an alternate manner to the working chambers on both sides of the vibration piston 8 by a shuttle valve 9. The shuttle valve can be, for example, a 2 / 4-way valve of the electromagnetically operated type. However, any other suitable valve can be used, such as a valve with a pivoting valve slide, a proportional valve and / or a servo valve. Via the shuttle valve 9, the chambers on the vibration piston 8 which are not pressurized at each time are alternately connected to a non-pressurized tank line T. As a result of the alternate pressure on the vibration piston 8, the vibration piston 8 is brought into a state of vibration and generates the axial force required for the advancement of the drill head 3. The frequency, i.e. the frequency at which the shuttle valve 9 is driven by a PLC (Programmable Logic Controller), is transmitted to the vibration piston 8 of the vibration generator 6. The symbolically indicated measuring transducer 10 allows the current position of the oscillating piston 8 to be detected and sent to the PLC. The actual stroke and frequency of the oscillating piston 8 can then be determined as derived variables. Through this measurement, the current response of the entire array, both the oscillating piston 8 and the pressurized fluid under pressure, can be detected, for example when the frequency of the shuttle valve 9 changes. The resulting control circuit allows the vibration generator 6 to be operated dynamically. Due to the detection of the position of the oscillating piston and the derived variables, such as the stroke and frequency, in real time, the control circuit can be realized. The desired reversal point of the oscillating piston 8 can be adapted in almost any way so that an improvement in the advancement of the illustrated drill drive is achieved.

[0032] A schematic circuit diagram of this hydraulic vibration drive is shown in FIG. 2. According to this diagram, a piston, also located in a housing and having a mass m, is moved by an actuation pressure p maxThe piston can be brought into vibration by applying a force of 0.0001 to the piston. In this figure, an electromagnetically controlled 3 / 4-way valve for alternating pressurization is symbolically shown. The supply of pressurized fluid is achieved by a fixed displacement pump with a pressure control valve. Here, the parameters of the overall arrangement according to the invention are depicted diagrammatically by the mass m and diameter D of the piston and the length l and diameter dN of the pressurized fluid supply line.

[0033] 3 shows the frequency response of the entire arrangement to the excitation of the vibratory drive according to the invention. In this example, a piston of mass 20 kg and diameter D 95 mm is driven by a fluid pressure p max In this case, the vibration drive was excited in the frequency range 0-1000 Hz according to an exemplary method. As clearly demonstrated, the maximum force delta F (at the level of about 95 kN) is obtained at a resonant frequency of about 180 Hz, which corresponds to the natural frequency of the entire arrangement including the vibrating piston and the pressurized fluid. The dynamic and variable alternating pressurization in the control circuit allows the desired parameters of the vibration and pulse generator according to the invention to be identified in a simple manner and to be rapidly adapted in case of changes in the associated conditions. Thus, the vibration or pulse generator according to the invention allows the improvement of the ground penetration of the construction machine tools, such as drills, chisels, ripper teeth, etc., coupled to the generator.

Claims

1. A device for construction machinery that generates vibrations. Housing and a piston (8) capable of reciprocating in a reverse direction within a working space in the housing between a first reversal point and a second reversal point; a pressurized fluid supply (P) capable of directing pressurized fluid into and out of the working space near the first and second reversal points, respectively, thereby bringing said piston (8) into said reciprocating reverse motion, thereby generating said striking pulse or vibration; at least one controllable valve (9) capable of directing said pressurized fluid into and / or out of said working space; a control unit (PLC) connected to said at least one controllable valve (9) and capable of controlling and varying the movement of said piston (8) within said working space; An apparatus having Measuring means (10) are provided for determining the position of the piston (8) in the working space, The control unit (PLC) is designed to move the piston (8) in a counter-reciprocating motion while changing the frequency, identify the frequency at which the frequency response of the device is maximized from the detection results of the measurement means (10) as a resonant frequency, and move the piston (8) at the same frequency as the resonant frequency.

2. 2. An apparatus according to claim 1, comprising:

4. The device according to claim 3, wherein the controllable valve (9) is a solenoid valve.

3. 2. An apparatus according to claim 1, comprising: The device, characterized in that the measuring means (10) comprises a linear sensor.

4. A device according to any one of claims 1 to 3, A device characterized in that a striking surface is arranged on at least one side of the reversal point, and a striking pulse is generated by the piston (8) striking the striking surface individually.

5. A device according to any one of claims 1 to 4, A device, characterised in that the mass of said piston (8) and / or said housing can be varied by installing or removing adjustment weights.

6. A construction machine, A construction machine, characterized in that it is equipped with a device for generating vibrations according to any one of claims 1 to 5.

7. A construction machine according to claim 6, 1. A construction machine characterized in that it is an earth drilling device.

8. A construction machine according to claim 6, A construction machine which is a pile driver or a vibrator.

9. A method for generating vibrations by a device according to any one of claims 1 to 8, comprising the steps of: A piston (8) is caused to perform a reciprocating motion in a working space in a housing between a first reversal point and a second reversal point, A pressurized fluid is used to bring the piston (8) into a reciprocating motion in order to generate the vibration, and the pressurized fluid is guided into and out of the working space near a first reversal point and a second reversal point; at least one controllable valve (9) for directing pressurized fluid into and / or out of said working space, controlled by a control unit (PLC); and A method for controlling the movement of said piston (8) by said control unit (PLC), comprising the steps of: The control unit (PLC) causes the piston (8) to move in a counter-reciprocating manner while changing the frequency, and identifies the frequency at which the frequency response of the device is maximized as a resonant frequency; The method comprises controlling said at least one controllable valve (9) by said control unit (PLC) to move a piston (8) at a frequency equal to said resonant frequency.

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