SK18442001A3 - Oil-dynamic percussion machine and a modulator slide valve - Google Patents

Abstract

Oil-dynamic percussion machine having a body (1) in which there are a piston (3) which transforms the hydraulic power of the feeding circuit in mechanical power, a tool (5) that transfers the mechanical power to produce the demolition work, a Nitrogen-filled high pressure hydraulic accumulator (2) having the function of storing the hydraulic power supplied by the feeding circuit and characterised by a modulator slide valve (4) that keeps the operating pressure at a constant value; this mechanism controls the motion of the piston, his active displacement and the oil inlet and discharge control ports (19, 11).

Description

Oil-dynamic impact machine and modulator slide valve

Technical field

The invention relates to an oil-dynamic impact machine, the basic characteristic of which is the absence of any hydraulic control device, control or adjustment valves.

BACKGROUND OF THE INVENTION

Most alternative oil-dynamic impact machines known in the art operate on the same basic principle: the piston, driven by a high-pressure incompressible fluid, accelerates to a high speed and encounters a tool that performs demolition. Impact energy in the form of compressed energy is stored in a charge of nitrogen (or other equivalent gas). The high pressure in the rear chamber is directly connected to the high pressure line (circumference) acting on the central region of the piston, assisting the stroke of the piston.

Other mechanisms connect alternatively high and low pressure lines to the piston head. In these mechanisms, the piston moves alternately to extreme positions, called upper dead center and lower dead center. The impact energy is directly proportional to the piston stroke and the sum of the dynamic forces acting on it.

Oil pressure in the rear chamber should be maintained at a constant oil-dynamic pressure in the battery as the impact energy value depends on it, special valves controlled by the battery pressure regulate the discharge port to vary due to pressure drop between dynamic pressure which is created at the piston head and by the pressure in the return line. This means that the dynamic pressure value in the battery is inversely proportional to the piston stroke speed.

A valve of this type is described in European patent no. 0085279 and is a complete part of the device described in U.S. Pat. 4,380,901.

The disadvantage of these solutions is the control of the pressure control valve. This is a highly unstable element due to very short time constants and difference

-2between its control characteristics and operating conditions characteristics.

This instability leads to high-pressure impacts on the piston head, which cause the vibration and bouncing of the percussion machine. It is therefore necessary to regulate the hydraulic system of the working machine or check valves, especially during installation. As a result, incorrect regulation results in damage to the machine structure due to high mechanical stress or excessive impact, which significantly shortens the life of pumps, pipes, switchgear and so on. Finally, another disadvantage is the hydraulic seal, which usually affects the machine / line system under operating conditions due to any type of lamination, causing thermal stresses that reduce line reliability and performance. This dynamic seal can only be realized using special types of materials.

SUMMARY OF THE INVENTION

These technical problems are solved by an oil-dynamic impact machine which has no external control element and consequently no high-pressure dynamic seal. The advantage is that the top dead center of the piston can be changed automatically without any control, regulating or control device, and thus the active displacement of the pusher chamber and the impact energy on the hydraulic tool can be changed in real time; all of this is done using an oil-dynamic auto-control of an element called a modulator. In this way, the pressure value in the oil-gas accumulator is kept constant. This means that the working pressure and therefore the active force on the piston are kept constant, which improves the reliability of the impact system as well as the body frame and hydraulic service lines.

It is necessary to emphasize the difference between the novel modulator according to the invention and the normal and known sliding valve. Generally, both pneumatic and hydraulic devices include a distributor or a sliding valve to generate pressure. This distributor or slide valve has ON control and moves fluid to extreme positions. A similar device is disclosed in U.S. Pat. 368/15 and no. 0085279, which is said to be part of a system that limits the upward travel of the distributor by overtaking the start-up phase of the piston downward relative to the top dead center. These devices are combined with others that allow the pressurized liquid to be pumped out at different speeds from the manifold protrusion in the 2C annular chamber by forming the same protrusion at the top of the groove 2. A similar device is described in U.S. Pat. No. 4,380,901 with a valve connected to a high-pressure line which is determined by the Law of Motion. In the device described in French Patent No. 5,958,549, 8114043, the one-way valve causes an alternative movement of the piston. Therefore, it is clear from the literature and the prior art that neither the stroke of the distributor nor its speed can be controlled without an external device or other means. With the hydraulic sliding modulator according to the invention, the outlet of the hydraulic line is automatically controlled by the position of the modulator. This is a new development of the traditional winding type switchgear.

Another object of the invention is easy installation in operation due to the absence of adjustment procedures and flow and operating pressure control. Therefore, the invention solves the specific problem of hiring hammers where daily operation and maintenance are difficult tasks, since an oil-dynamic impact machine can be used on a variety of machines and lines as needed.

These and other advantages will be described in more detail in the detailed description of the invention with reference to Figures 1/7, 2/7, 3/7, 4/7, 5/7, 6/7 and 7/7, which illustrate some possible schemes as non-limiting examples and how the invention works.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a vertical sectional view of the invention;

Fig. 2 and FIG. 3 show the same diagram in two different operating positions;

Fig. 4 shows an enlarged detail of the piston head and the inner base of the modulator;

Fig. 5 and FIG. 6 illustrate the geometry and resulting control characteristic of the lower and upper discharge orifices;

-4Obr. 7 shows a detail of the internal protection system;

Fig. 8 and FIG. 9 represent possible changes in piston geometry.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, the oil-dynamic impact machine according to the invention comprises the following basic components: body 1, nitrogen-filled high-pressure hydraulic accumulator 2, piston 3, slider-type modulator valve 4, tool 5, high-pressure supply line 6, upward lift 7 with upward lift guide 7a space, low pressure discharge line 8, low pressure volume modulator 9, hydraulic shock absorber modulator 10, pusher volume control openings 11, annular volume connection 12, lower modulator discharge line 13 and modulator lower discharge line 13a, volume lift modulator 14, volume modulator control openings 15, the pressure volume 16, the piston hydraulic shock absorber 18, the high-pressure outlet ports 19, the accumulator supply line 20, the accumulator through-holes 21, the overflow valve 22 shown in FIG. 7, piston pre-opening zone A, modulator sliding valve pre-opening zone 3, modulator upper dynamic seal passage C, modulator lower dynamic seal passage D, body upper dynamic seal E, body dynamic internal seal F, hydraulic shock absorber passage G, modulator internal calibrated zone H.

The invention comprises an essential component: a dual-chamber accumulator, equipped with pressurized oil and nitrogen gas, separated by a rubber membrane holding nitrogen. The oil-filled chamber is connected to the high pressure line of the hydraulic circuit and to the central part of the piston to push the piston up. The oil-filled chamber is also connected to the pressure chamber to which the modulator sliding valve supplies pressurized oil.

The pressure in the oil chamber depends on the ratio of the inlet flow rate and the pulse outlet flow rate. The discharge flow is a function of the following parameters:

(a) the speed of the piston upward movement, which determines the time of oil being discharged through the discharge line as a function of the pressure drop that has occurred. The outlet orifices are automatically controlled by the top dead center of the modulator sliding valve that modulates the orifice;

(b) variations in the upward stroke of the piston which determines the amount of passive cycle oil or return;

c) varying the stroke of the modulator sliding valve, which determines the position of the top dead center of the piston as well as its stroke;

(d) pressure surges in the compression chamber due to kickbacks from the piston. The invention eliminates these pressure surges by opening the outlet opening before impact.

e) hydraulic deceleration characteristics during the last part of the modulator upward movement;

(f) the total duration of the active / passive duty cycle.

The modulator valve interacts with the piston to automatically determine the sequential control of the above parameters.

Example

Referring to FIG. 1, the modulator coil valve 4 is in the rest position and the piston 3 is at the bottom dead center. The modulator lower discharge lines 13 and 13a are closed. From line 6 of the high pressure supply circuit, the oil flows to the top of the printing volume 7 via line 7a and to the press chamber 16 via the high pressure oil inlet 9. The oil in the secondary supply line 20 through holes 21 compresses nitrogen in the high pressure oil-gas accumulator. pressure to low pressure is provided by the connection between the modulator and the housing. Under these conditions, the high pressure feed acts on the piston head 3 and on the upward pushing volume 7. Taking into account the difference in area, the high pressure pushes the piston downwards as opposed to movement from the tool response.

At the same time, the high supply pressure acts on the exposed surface of the modulator slide valve 4, which has a volume 9 connected to the low pressure line 8 through the holes in the pressure volume 11 and the discharge line 8 of the modulator coil valve. The difference in pressure areas together with the static pressure difference between the inlet pressure and the discharge pressure determine the upward force that lifts the modulator coil valve 4 up to the maximum allowable stroke; this

In this way, the inlet 19 is closed and the pressure volume opening 11 is opened. At the end of its stroke, the modulator coil valve 4 is slowed by the hydraulic damper modulator 10 and the oil contained in the volume 14 is forced through the opening 15.

In this way, the static pressure value in the volume 16 is reduced, thereby allowing the upward force in the pressure volume 7 to prevail and to begin the upward movement of the piston 3, causing the residual oil to be displaced into the volume 16 in the low pressure discharge line 8 through the inspection port 11.

At this stage, the high-pressure oil inlet 19 is closed and the oil from the high-pressure oil feed line feeds the oil-gas accumulator 2 through the circuit line 20 and the openings 21 up to the dynamic supply circuit pressure.

The piston 3, which can rise freely (FIG. 2), enters the modulator coil valve 4 and pushes against the increasing volume of the modulator sliding valve 14 through the apertures 15 determining the force of the modulator 4 downwardly pushing the piston down, the lower discharge line of the modulator 13 13a is open.

The dynamic interaction between the movement of the piston 3 back and forth and the opposite movement of the modulator sliding valve 4 ends when the modulator sliding valve opens the high pressure oil inlet 19 (reaching the maximum inclined position) and when closing the opening 11 recreates the dynamic passage seal D. 6 the oil enters both the pressure volume 16 and the upward pressure volume 7 due to the volume of nitrogen compressed oil contained in the accumulator 2. Therefore, the same pressure value acts on both the upper part of the piston 3 and the lower part of the volume 7, exerting a downward force proportional to the difference between the two surfaces. The resulting force is equal to the sudden downward pressure exerted on the piston 3, giving it a uniformly accelerated movement.

If the surface A of the piston 3 reaches position B of the modulator coil valve 4 before it should (due to the impact position on the tool that previously closed the circuit 13, 13a), this eliminates the dynamic A / B passage and allows high pressure active oil fully pressurized the modulator coil valve 4, which generates a volume 9 at low pressure. The low pressure volume 9 of the modulator slide valve 4, multiplied by the difference in pressure between that generated in the accumulator 2 and that in the outlet existing in the volume 9, determines the force,

This force propels the modulator up, closing the high pressure oil inlet 19 in the direction of the control 14 of the modulator printing volume up.

The modulator sliding valve 4 transforms the kinetic energy by entering the upper modulator control volume 14 at high speed, creating a dynamic passage E, F, pressurizing the modulator control volume 14, and partially opening the pressurization orifices 11 to force oil (trapped in volume).

14) to flow through the apertures 15, having an exponential type of control characteristic.

If the dynamic pressure in the volume 16 is very high and the oil is completely pushed out of the volume 14, the modulator sliding valve 4 stops at the top dead center. In contrast, if the dynamic pressure generated is very low, the modulator sliding valve 4 ends its stroke when it enters volume 14 and begins to pressurize it. Similarly, if the modulator sliding valve 4 is heavier loaded, it opens a higher portion of the pusher volume inspection opening 11, determining a low hydraulic resistance to be drained; the piston 3 is accelerated due to the small pressure difference when discharging oil without energy through the lower orifices 11 of the pressure volume. Therefore, by shortening the extrusion time, the pressure in the accumulator 2 tends to decrease.

The piston 3 strikes the tool 5 and moves upward at a rate that is a function of the difference between the upward pressure and the discharge pressure existing in the chamber 16 multiplied by the pressure surface of the piston 3. During the upward stroke the piston enters the modulator slide 4 at its variable top dead center. The lower part of the piston is connected to the open discharge line 12, 13, 13a, moves downward, opening the apertures 19 and restoring the operating cycle. This makes it possible to maintain a constant value of the predetermined operating pressure.

The degree of accuracy of defining the geometry of the fluid-dynamic passage to optimize the fine adjustment and timing of the modulator slide valve 4 is very important. The aim is not to have surfaces with different velocities: the resulting pressure changes can affect the time constant of the modulation system. Therefore, the path by which the oil must cross the annular opening and then in the defined pressure volume 16 must be optimized. Piston head 3 of inverted cone shape

-8 creates an inlet passage with an inner curve and a conical base of the modulator slide valve 4 (Fig. 4). The purpose of this special geometry is to transform the kinetic energy of the liquid in real time into an instantaneous pressure energy that immediately moves the modulator slide valve 4. The liquid then passes through the volume control openings 11, modulating the modulator rest position. These openings 11 may have a different shape as described in FIG. 5: a circular cross-section, rectangular or trapezoidal in accordance with the law to be used.

Similarly, the discharge openings 15 (FIG. 6), which determine the varying top dead center position of the modulator slide valve 4, have different shapes. In general, the apertures have an exponential type control characteristic as a function of the stroke. For short strokes, linear type controls can be used with considerable simplification of construction and low accuracy of the top dead center control position of the modulator.

The impactor according to a further preferred embodiment is characterized in that the machine has a hydraulic damper 10 which protects the modulator sliding valve 4 from mechanical stress. It prevents the modulator sliding valve 4 from accidentally against. After the modulator slide valve 4 has risen to its upper position, the volume 10 formed between the maximum top dead center of the modulator 4 and the passages C and G will allow the inertial energy of the modulator to be transformed into thermal energy.

The impactor according to another embodiment is characterized in that the machine has an internal protective system (Fig. 7) to maintain the level of the internal operating pressure and consequently the impact energy of the piston on the tool within the mechanical stresses envisaged in the design phase.

The internal protection system shall be actuated in the event of an abnormal operation of the hydraulic circuit, which entails problems of excessive flow or unexpected fluctuations.

As described above, the volume control apertures 14 relative to volume 16 have an exponential type control characteristic, so the constant time should be shortened so that the modulator sliding valve 4 reaches the maximum stroke in the shortest possible time, supporting operating conditions for maximum displacement (maximum). working oil consumption). For this purpose, the stroke control volume 14 of the modulator slide valve is equipped with a second ON-OFF control circuit which can operate in this extreme case. This second circuit has a simple BY-PASS directly connected to the accumulator and a non-return valve 22, which has a priority function as previously described and shown in FIG. 7th

Finally, two important aspects to properly dimension the invention should be emphasized: the first is that the impact efficiency increases with the impact velocity increase, and the second is that the impact velocity when the piston acceleration is constant increases with the piston stroke increasing. It is also known that the impact energy is proportional to the square of the impact velocity, therefore, in the design phase, to take account of what has been said, the stroke values of the piston must be maintained within certain predetermined criteria.

As a result, the compression active diameter (DV16) of the piston, which is directly subjected to high pressure, must be reduced proportionately.

The impactor can be modified according to different models or sizes, while maintaining the same principle of operation. Fig. 8 and FIG. 9 show two variants of the geometry of the piston 3 in which the active pressure diameter is reduced.

Claims (11)

PATENT CLAIMS An oil-dynamic impact machine having a body (1) having a piston (3) that transforms the hydraulic force of the supply circuit into an external mechanical force, a tool (5) that transmits the mechanical force, channels (7a), ( 20), (6), inspection openings (19, 11, 15), inspection and pressure volumes (7, 16) that allow the incompressible fluid (e.g. oil) to transform the hydraulic force into a mechanical force; it also includes a nitrogen-filled high-pressure hydraulic accumulator (2) having the function of storing hydraulic energy supplied by the supply circuit (6) and returning it to the piston (3), characterized in that it comprises a modulator sliding valve (4) which maintains pressure at constant value; this mechanism controls the movement of the piston, its active displacement and the inspection holes (19, 11) of the oil inlet and outlet. Oil-dynamic impact machine according to claim 1, characterized in that it does not need either control valves for flow control, pressure relief, control of the operating pressure and / or active or passive displacement, nor mechanical stops for the piston stroke. An oil-dynamic impact modulator sliding valve (4) characterized by moving exclusively oil-dynamically and by hydraulic interaction with the piston (3). Modulator sliding valve according to the preceding claim, characterized in that its geometry, its particular shape together with the positions of said inlet port (15) and the discharge port (11) and of the pressure and control volumes (16, 14) are very important when changing the piston stroke (3), active displacement as well as the operating frequency. A modulator slide valve according to claim 3 or 4, characterized in that it automatically controls its own position, dissipating kinetic energy in the volume (14) and in the passages (E) and (F), wherein said modulator slide valve comprises a calibrated internal valve. and an outer surface, which together with the calibrated body portions (1) form a passage (E), (F). Modulator slide valve according to any one of claims 3 to 5, characterized in that it can control all operating parameters by means of which the pressure in the oil-gas accumulator (2) and the impact energy can be kept constant. An oil-dynamic impact machine according to claim 1 or 2, characterized in that the oil paths inside the machine optimize the sensitivity and timing of the modulator slide valve. Oil-dynamic impact machine according to claim 1, 2 or 7, characterized in that the upper (15) and lower (11) discharge ports are operated with a particular control characteristic. An oil-dynamic impact machine according to claim 1, 2, 7 or 8, characterized in that it comprises a hydraulic damper (10) which prevents (when the modulator slide valve is close to its dead center) impact between the body (1) and by a modulator slide valve (4). An oil-dynamic impact machine according to claim 1, 2, 7, 8 or 9, characterized in that it comprises a secondary BY-PASS circuit (22) which, in the case of excessive and unexpected flows, in the high-pressure hydraulic supply line with its opening allows the system to reduce the pressure in the battery. Oil-dynamic impact machine according to claim 1, 2, 7, 8, 9 or 10, characterized in that the rapid opening of the discharge ports (11) and the rapid closing of the oil discharge ports (19) in said volume (16) prevent regeneration. energy and therefore any pressure surge in the pressure volume (16).