HK40069250A - Device for generating percussive pulses or vibrations for a construction machine - Google Patents

Description

Device for generating impact pulses or vibrations for construction machines

Technical Field

The invention relates to a device for generating impact pulses or vibrations for a construction machine according to the preamble of claim 1, having: a housing; a piston reversibly reciprocable in a working space in the housing between a first reversal point and a second reversal point; and a pressure fluid supply by means of which pressure fluid can be introduced into and removed from the working space in the region of the first and second reversal points in each case, wherein the piston can be set into a reversible movement in order to generate a shock pulse or oscillation; having at least one controllable valve through which pressure fluid can be conducted into and/or out of the working space; and a control unit connected to the at least one controllable valve, wherein the movement of the piston in the working space can be controlled and varied by the control unit.

The invention also relates to a method for generating impact pulses or vibrations for a construction machine according to the preamble of claim 11, wherein a piston is reversibly reciprocated in a working space in a housing between a first reversal point and a second reversal point; wherein for the purpose of generating the impact pulse or the oscillation the piston is arranged to be reversibly moved by means of a pressure fluid, and the pressure fluid is led into and out of the working space in the region of the first and second reversal points, wherein the control unit controls at least one controllable valve, through which the pressure fluid is led into and/or out of the working space, and the movement of the piston is controlled by the control unit.

Background

A general vibration generator is known from EP 3417951 a 1. In this known vibration generator, the working space in the housing is divided by the working piston into two pressure chambers. Via the inlet and the outlet, the two pressure chambers are selectively supplied or discharged with pressure fluid in an alternating manner, so that the working piston is reversibly moved and generates vibrations. The timed supply and discharge of pressure fluid in the individual pressure chambers takes place via a complex arrangement of controllable valves and conduits in the housing. Furthermore, a measuring device is arranged inside the working piston, by means of which the position of the working piston in the working space and thus the position relative to the housing are precisely determined. By means of the control device, both the opening and/or closing time of the controllable valve and further parameters for the pressure fluid supply can be set. By varying these parameters via the control device, it is in particular possible to vary both the frequency and the stroke of the working piston in the housing. In the program memory, different parameters can be stored which produce a selective actuation of the vibration generator, so that the frequency and the stroke length for an optimum adjustment of the vibration generator are selected for the working application.

In the known vibration generator, it is in fact possible to vary the frequency and the stroke to a limited extent in order to set vibration parameters suitable for the application. However, for the general determination of the vibration parameters and for the setting of the vibration system, the mass of the vibration piston is mainly utilized. In particular, the appropriate frequency is estimated based on the piston mass.

Further mechanical control means in the vibration generator can also be taken from GB-A-920158, US-A-4026193 or US-A-4031812, for example. All these known devices have a working piston and a control piston which open or close certain ducts depending on the respective position in the housing, thus causing the selective alternate supply of two opposite pressure chambers to move the working piston.

This type of equipment is time consuming and costly to produce. Furthermore, due to the piping layout, the specific vibration or shock behaviour of the piston is predetermined at a predetermined pressure level. Variations in vibration frequency and impact energy are only possible to a very limited extent and in some cases require laborious mechanical reworking.

Disclosure of Invention

The invention is based on the object of providing a device and a method for generating shock pulses or vibrations, with which a particularly effective shock or vibration behavior can be achieved.

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 set out in the dependent claims.

The device according to the invention is characterized in that the control unit is designed to move the piston at a frequency corresponding to a resonance frequency of an overall arrangement (overall arrangement) comprising the piston and the pressure fluid. The finding of the invention is that the overall arrangement of the device for generating shock pulses and/or vibrations depends not only on the properties of the piston, such as its diameter and its mass, but also to a decisive extent on further parameters influencing the pressure fluid, preferably the pressure generated, the line cross-section, the line length, the line shape and surface and in the case of its control edges (control edges) and the valve slide arranged in the housing of the control valve, the switching time and shape of the valve slide. These further parameters can have a decisive influence on the resonance frequency and the associated piston stroke and thus on the force transmitted or the impact pulse transmitted by the device according to the invention.

The basic idea of the invention lies in the fact that: the variable actuation now possible of the piston (i.e. the vibration and/or shock pulse generator) is improved in such a way that its pressurization with pressure fluid is carried out using parameters adapted to the system and the desired application, in order to enable improved insertion of e.g. a tool attached to the vibration and shock pulse generator into e.g. different ground. By determining the resonance parameters, including the overall arrangement of the piston and the pressure fluid, it is possible to determine, on the one hand, the appropriate resonance frequency and resonance stroke, and, on the other hand, due to the possible variable actuation of the vibration generator, dynamic adjustment of the parameters to accommodate changes in the process can also occur during operation. For example, in a soil drilling method, these changes may be caused by the alternation of soil or rock layers to be inserted. In addition, various auxiliary conditions can also have an effect on the resonant frequency, such as wear and tear, aging, changes in temperature and viscosity of the pressure fluid, and the like.

Thus, in the device according to the invention, the now possible dynamic adjustment of the parameters can take place in real time during operation, and due to the continuous detection of the actual vibration, the resonance frequency can be substantially optimized in the control loop, in order to achieve an improved vibration of the piston and thus an increased force and/or pulse generation. It is therefore possible to create a multifunctional vibration circuit which allows a very wide use of the device in construction machines.

For the device according to the invention, basically all suitable controllable valves can be used. According to a further development of the invention, the valve is particularly suitable as a solenoid valve. The valve body can be adjusted by a solenoid arrangement between open and closed positions. It is also possible to set an intermediate position so that the amount of pressure fluid supplied to the working space can be set. Basically, any type of pressure fluid can be provided, in which case hydraulic oil is preferably used.

The preferred embodiment variant of the invention consists in the fact that: a measurement device for determining a position of a piston in a workspace is provided. With regard to the measuring device, all usable sensors for length or position measurement can be used, which operate in particular optically, capacitively, inductively, magnetically or otherwise.

According to an embodiment of the invention, it is particularly advantageous that the measuring device has a linear sensor. This is particularly suitable if the piston moves linearly in the housing between two reversal points.

Basically, the piston can move reversibly in the housing, so that the piston does not contact the wall of the housing with its two front surfaces. In this way, the device can be used as a so-called vibration generator. An advantageous embodiment of the invention consists in the fact that: at least one reversal point is arranged with an impact surface, on which the piston deliberately strikes in order to generate an impact pulse. Basically, the impact surfaces can be arranged on two opposite front surfaces of the piston on the housing. Preferably, however, only a single impact surface is present, so that for e.g. impact drilling, a specific impact pulse can be generated as desired.

According to another preferred variant, the overall arrangement comprises a housing. In this way, further factors and parameters influencing the vibration circuit can be represented, such as the cross-section and roughness of the pipes for introducing and removing pressure fluid into and from the working space, and possible elbow losses (elbows) of these pipes in the housing.

According to a further variant of the invention, the frequency and/or the stroke of the piston can be set and adjusted, preferably by means of a control unit. In order to vary the frequency, it is possible to set, in particular, the opening and closing times by means of the control unit and, where appropriate, the supply of hydraulic energy. Furthermore, varying the position of the two reversal points by the respective opening and closing of the controllable valves enables the stroke of the piston. For this purpose, the control unit preferably has an input interface, such as an input area. Furthermore, the control unit can be operated in a simulated manner by the operator directly by means of conventional machine control from the operating unit.

According to a further preferred embodiment of the invention, the mass of the piston and/or the housing can be changed by installing or removing the adjusting weight. In particular, when vibration or shock pulses are generated in the apparatus, changes in the piston and/or cylinder mass cause significant changes in the resonant frequency. It is the combination of the variable actuation of the pressure fluid achieved by setting the piston reversal point and the mass of the piston or housing fitted to the piston that enables a wide range of applications to be covered with this system.

Another preferred embodiment variant of the invention can be seen from the fact that: the control unit has a program memory in which different control programs for controlling the piston can be stored. For example, a particular control program can be stored for a specific application purpose. For example, at the start of the program, a high frequency can be provided with a small piston stroke, whereas in the program sequence the piston stroke then increases with time and the frequency decreases with time. Almost any number of different program sequences can be provided to control the piston with respect to frequency and stroke. For example, a program for a fast travel or a particularly slow drive process can be provided. Further, programs for specific types of soil can be stored. The control unit can preferably comprise an automatic program for determining the resonance frequency. In this case, upon actuation of the piston, a frequency band is traversed from the starting frequency to the target frequency, and in so doing, the corresponding response frequency of the device is detected via the vibration sensor. The maximum value of the response frequency constitutes the resonance frequency.

The invention also comprises a construction machine, characterized in that the device for generating impact pulses or vibrations described above is arranged on a construction machine. In particular, the construction machine can be provided for use in ground engineering. However, the device can also be used for other construction machines with other tools, in which the insertion of the working edge or the material to be introduced into the ground is facilitated by applying vibrations by means of an oscillating mass. This may be, for example, the digging shovel of an excavator and the attachment chisel for an excavator.

According to an embodiment of the invention, it is particularly advantageous that the construction machine is a soil drilling rig. If the apparatus is provided for generating impact pulses, impact drilling can be performed. This is particularly advantageous when inserting into harder rock formations. Alternatively or additionally, the device can also be designed to be free from impact contacts for generating vibrations. In soil drilling installations with a drilling tool which is driven in a rotating manner, so-called overburden drilling (overburden drilling) can therefore be carried out in particular. In this case, the rotary motion of the drilling tool superimposes a vibratory or oscillatory motion. By means of the superimposed vibrations, quasi-liquefaction of the ground can be achieved at least in the contact area with the drilling tool, which promotes an improved drilling progress.

Another embodiment of the invention can be seen in the fact that: the construction machine is a pile driver or a vibrator. Such drivers or vibrators can be used for the guidance of, for example, steel beams, piles or sheet piles which are driven into the ground by means of impact pulses or vibrations.

The method according to the invention is characterized in that the at least one valve is controlled by the control unit such that the piston is moved at a frequency corresponding to the resonance frequency of the overall arrangement comprising the piston and the pressure fluid.

This overall arrangement of the device for generating shock pulses and/or vibrations not only characterizes the piston, such as its diameter and its mass, but also includes parameters that influence the vibration circuit, such as applied pressure, existing line cross-section, line length, line shape and surface, and switching times and shape of the valve slide in the case of its control edge and the valve slide being arranged in the housing of the control valve. These further parameters can have a decisive influence on the resonance frequency and the resulting piston stroke and thus on the force transmitted by the method according to the invention or the impact pulse transmitted thereby.

According to a further development, it is advantageous if the position of the piston is detected by means of a measuring device, and, depending on the detected position of the piston, the control unit controls at least one controllable valve, through which pressure fluid is conducted into and/or out of the working space, wherein the movement of the piston is controlled by means of the control unit.

The method according to the invention can be carried out in particular using the apparatus described above. Thereby achieving the advantages described above.

Drawings

The invention is further described below by means of preferred embodiments schematically illustrated in the drawings, in which:

FIG. 1: a schematic cross-sectional view of a device according to the invention;

FIG. 2: a circuit diagram of an apparatus according to the invention; and

FIG. 3: frequency diagram of the device according to the invention.

Detailed Description

Fig. 1 shows a principle drawing of a drill drive (drill drive) equipped with a vibration or shock pulse generator according to the invention. Here illustrated as a housing 1 comprising all functional components. From this housing there projects a drill rod 2, which drill rod 2 carries a drill bit 3 at its distal end. By means of the hydraulic motor 4, the drill rod 2 is arranged in a rotational movement about the axis of the drill rod 2 via a planetary gear 5. A drilling tool is arranged on the drill bit 3. By the rotary movement of the drill bit 3, the cutting edge of the drilling tool is able to strip away chips in the drill hole. The thickness of the chip depends on the force applied in the axial direction. In order to generate an alternating axial vibration force, a vibration generator 6, which substantially corresponds to the vibration or shock pulse generator according to the invention, is mounted on the planet gear 5. The vibration generator 6 is supported in a rubber spring 7, and the rubber spring 7 separates the generated vibration from the housing. In addition to the oscillation/vibration generator 6, the vibration of the tool drive and thus the moving mass also comprise the drill bit 3, the drill rod 2, the planetary gear 5 and the hydraulic motor 4, which are thus supported in the axial guide 11. Alternatively, the gear 5 can also be operated separately from the vibration unit or vibration generator 6. In this case, by way of example, the generated vibration energy is transmitted directly to the drill rod and thus to the drill bit via a shaft which is guided through an output shaft designed as a hollow shaft. In this case, the rotary motion generated by the gear can be transmitted from the hollow shaft into the drill rod and thus to the drill bit via the tooth connections or any tooth profile which separates the generated axial vibrations from the gear. Alternatively, it is also possible that the shaft transmits a rotational movement and the hollow shaft transmits the generated vibrations.

In order to generate vibrations in the vibration generator 6, this vibration generator 6 comprises a vibration cylinder or rather a vibration piston 8 which is pressurized in an alternating manner by a pressure fluid in pressure chambers located on both sides of the vibration piston 8. Pressure fluid is provided in the pressure fluid line P and is applied in an alternating manner to the working chambers on both sides of the vibrating piston 8 by means of the reversing valve 9. For example, the directional valve can be a solenoid operated 2/4 directional control valve. However, all other suitable valves can also be used, for example with a rotating valve slide, a proportional valve and/or a servo valve. Via a reversing valve 9, the chambers (in each case unpressurized) on the vibrating piston 8 are alternately connected to a pressureless container line T. Due to this alternating pressurization of the vibration piston 8, the vibration piston 8 is set to vibrate and generate the axial force required for the travel of the drill bit 3. The frequency with which the directional valve 9 is actuated by the PLC (= programmable logic controller) is transmitted to the vibrating piston 8 of the vibration generator 6. Via a symbolically indicated measuring sensor 10, the current position of the vibrating piston 8 can be detected and transmitted to the PLC. As a result of the variables derived therefrom, the actual stroke and the frequency of the oscillating piston 8 can also be determined. By this measurement detection, for example, if the frequency of the directional valve 9 changes, the current response of the overall arrangement including both the oscillating vibrating piston 8 and the pressurized pressure fluid can be detected. In this way, a control loop is obtained, by means of which the vibration generator 6 can be dynamically operated. The detection of the position of the vibrating piston and the detection of variables derived therefrom, such as piston stroke and frequency, are carried out in real time in order to enable a control loop. The desired reversal point of the vibrating piston 8 can be adjusted in almost any chosen manner to achieve improved travel in the shown drill drive.

In fig. 2, a simplified circuit diagram of a hydraulic vibration drive is illustrated. In this case too, by applying the working pressure P_maxA piston having a mass m and located in a housing is set into vibration. Here, a solenoid-operated 3/4 directional control valve for alternate pressurization is shown symbolically. The pressure fluid supply takes place via a fixed displacement pump with a pressure control valve. In this case, the mass m and the diameter D of the piston and the length l and the diameter D of the supply line for the pressure fluid are measured_NThe parameters of the overall arrangement according to the invention are schematically illustrated.

Finally, in fig. 3, the frequency response of the overall arrangement with respect to the excitation (excitation) of the vibration driver according to the invention is shown. An exemplary piston mass of 20 kg with a piston diameter D of 95 mm is determined by the fluid pressure p_maxAnd (5) exciting. In this case, the excitation of the vibration drive is effected in the frequency range from 0 to 1000 Hz by way of example. It is evident that the force maximum Δ F (at a level of approximately 95 kN) is at a resonance frequency of approximately 180 Hz, which corresponds to the natural frequency of the overall arrangement comprising the vibrating piston and the pressure fluid. Due to the dynamic and variable alternating pressurization in the control loop, preferred parameters for the vibration and pulse generator according to the invention can be determined in a simple manner and these parameters can be adjusted rapidly in the event of changing auxiliary conditions. Thus, the vibration or pulse generator according to the invention enables an improved insertion of e.g. construction machine tools, such as drills, chisels, ripper teeth, etc., coupled to the generator into the ground.

Claims (11)

1. An apparatus for generating impact pulses or vibrations for a construction machine, having

-a housing (6);

-a piston (8), the piston (8) being reversibly reciprocable in a working space in the housing (6) between a first reversal point and a second reversal point;

-a pressure fluid supply (P) by means of which pressure fluid can in each case be introduced into and discharged from the working space in the region of the first and second reversal points, wherein the piston (8) can be set into a reversible movement in order to generate the impact pulse or oscillation;

-at least one controllable valve (9) through which the pressure fluid can be led into and/or out of the working space, and

-a control unit (PLC) connected to the at least one controllable valve (9), wherein the movement of the piston (8) in the working space can be controlled and varied by means of the control unit (PLC),

it is characterized in that the preparation method is characterized in that,

-the control unit (PLC) is designed to move the piston (8) at a frequency corresponding to the resonance frequency of the overall arrangement comprising the piston and the pressure fluid.

2. The apparatus according to claim 1, characterized in that the valve (9) is a solenoid valve.

3. An arrangement according to claim 1 or 2, characterised in that measuring means (10) are provided for determining the position of the piston (8) in the working space.

4. The apparatus according to claim 3, characterized in that the measuring device (10) has a linear sensor.

5. A device according to any one of claims 1-3, characterised in that an impact surface is arranged on at least one reversal point, onto which impact surface the piston (8) deliberately strikes in order to generate an impact pulse.

6. The apparatus of any one of claims 1 to 4, wherein the overall arrangement further comprises the housing.

7. Device according to any one of claims 1 to 5, characterized in that the mass of the piston (8) and/or the housing can be changed by installing or removing an adjusting weight.

8. A construction machine, characterized in that an apparatus for generating impact pulses or vibrations according to any one of claims 1-7 is arranged.

9. Construction machine according to claim 8, characterized in that it is a soil drilling rig.

10. Construction machine according to claim 8, characterized in that the construction machine is a pile driver or a vibrator.

11. A method for generating impact pulses or vibrations for a construction machine, in particular with an apparatus according to any one of claims 1 to 6,

-reversibly reciprocating a piston (8) in a working space in a housing between a first reversal point and a second reversal point;

-wherein the piston (8) is arranged to be reversibly moved by means of a pressure fluid for the purpose of generating the impact pulse or vibration, and the pressure fluid is led into and out of the working space in the region of the first and second reversal points,

-wherein a control unit (PLC) controls at least one controllable valve (9), through which at least one controllable valve (9) pressure fluid is led into and/or out of the workspace, and

-controlling the movement of the piston (8) by means of the control unit (PLC),

it is characterized in that the preparation method is characterized in that,

-said at least one valve (9) is controlled by said control unit (PLC) so that said piston (8) moves at a frequency corresponding to the resonance frequency of the overall arrangement comprising said piston (8) and said pressure fluid.