HUP0201028A2 - Innovative oil-dynamic percussion machine working at constant hydraulic pressure - Google Patents

Description

-2OIL-DRIVEN IMPACT TOOL.

The invention relates to a hydraulic-dynamic impact device, the essential feature of which is the absence of hydraulic control devices, check valves or adjustment valves.

Other prior art oleodynamic impactors operated on the same principle: a piston driven by a high-pressure incompressible fluid was accelerated to high speed and struck the demolition tool. The impact energy was stored in the form of pressure energy in an accumulator filled with nitrogen (or other equivalent gas). The high pressure in the rear head was directly connected to a high-pressure network acting around the center of the piston, assisting the upward movement of the piston.

In other designs, alternating high-pressure and low-pressure networks were connected to the piston head. In these designs, the piston was moved alternately to its extreme positions, called top dead center and bottom dead center. The impact energy was directly proportional to the piston stroke and the sum of the dynamic forces acting on it.

Therefore, the oil pressure in the rear head was kept at the average value of the oil-hydraulic pressure in the accumulator, since the value of the impact energy depended on it. Special valves controlled the pressure in the accumulator, regulating the outlet gate, thereby changing the pressure drop between the dynamic pressure determined at the piston head and the pressure in the return circuit. This means that the value of the dynamic pressure in the accumulator was inversely proportional to the piston rise speed.

This type of valve is described in European Patent Specification No. 0085279 and is incorporated in its entirety into United States Patent Specification No. 4380901.

The disadvantage of these applications was the pressure control valve. This is a very unstable element due to its very short time constants and the differences in its control characteristics and operating conditions.

This instability caused high pressure peaks at the piston head, which in turn caused vibrations and shaking of the impact device. Therefore, it was necessary to regulate the hydraulic system of the operating machine or the control valves, mainly insP-0171 PCT7IB00/00812

-3during the installation. As a result, inadequate regulation caused damage to the machine structure due to high mechanical stresses or excessively powerful strokes, significantly reducing the life of, for example, pumps, pipelines, distributors, etc. Finally, another disadvantage was the hydraulic sealing element, which generally acted on the machine/network systems under operating conditions, causing thermal stresses in any type of lamination, which reduced the reliability and performance of the network. This dynamic seal could only be made of special types of materials.

The invention relates to an oil-powered impact device comprising a body (1) 1, in which there is a piston (3) 3, which converts the hydraulic energy of the supply network into mechanical energy, a tool (5) 5, which transmits the mechanical energy, 7a, 20, 6 channels, 19, 11, 15 control openings 7, 16 control and thrust spaces, which allow the process of converting the hydraulic energy of an incompressible fluid (for example oil) into mechanical energy; including a high-pressure hydraulic accumulator 2 filled with nitrogen, whose function is to store the hydraulic energy supplied by the supply channel (6) and return it to the piston 3; this device further comprises a control slide valve 4, which maintains the operating pressure at a constant value; This structure controls the movement of the piston, its active displacement and the oil inlet and outlet control openings 19, 11.

Our invention solves the above-mentioned technical problem, since the impact device has no external control element and thus no high-pressure dynamic seal. Its advantage is that the top dead center of the piston can be automatically changed without any kind of backlash, regulating or control device, thus modulating in real time the active displacement of the push chamber and the impact energy on the tool in the hydraulic device; all this is achieved by the oil-dynamic self-control of an element called a modulator. In this way, the pressure value in the oil-gas accumulator is kept at a constant value. This is the operating pressure and therefore the active force on the piston is kept at a constant value, improving the reliability of the impact system and also the reliability of the body and the hydraulic operating circuit.

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-4It is necessary to point out the difference between the new modulator of our invention and the conventional and known slide valves. Generally, both pneumatic and hydraulic devices have included a distributor or slide valve for supplying pressure. This distributor or slide valve has an "open-close" control and is moved by the fluid to its end positions. A similar device is described in European Patent Specification EP0085279, in which it is mentioned that it is part of the upward stroke limit of the distributor, anticipating the phase of the piston start-up with respect to the top dead center. These devices were combined with others that allowed the compressed fluid to exit at different speeds from the projections of the distributor, in the annular chamber 2C formed by the same projection in the upper part of the groove 2. A similar device is described in United States Patent Specification No. 4380901 with a valve connected to the high-pressure line which determines the laws of movement. In French Patent Application No. 8114043, a one-way valve caused the alternating movement of the piston, it is evident that neither the distributor Neither its stroke nor its speed could be controlled without an external device or other means.

With the hydraulic sliding modulator of our invention, the opening of the outlet ports of the hydraulic circuit is automatically controlled by the position of the modulator. This is a novel development compared to the traditional spindle-shaped distributor.

Our invention is also easy to install during use, as there are no adjustment procedures and no checks on the flow and operating pressure. Thus, the invention solves the specific problem of hammer rental, where daily servicing and maintenance are difficult, as the dynamic impact device can be used on different machines and networks as needed.

The invention will be described in more detail with reference to Figures 1 to 7, which show some possible embodiments and how the invention works. Explanation of the figures: Figure 1: vertical section of the percussion device;

Figures 2 and 3: the same in two different operating positions;

Figure 4 is an enlarged view of a portion of the piston head and the lower part of the control;

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Figure 5 and Figure 6: the geometry of the entry and exit gates and the resulting characteristic. Figure 5: the characteristic of the 11 gates; volume: 16; from top to bottom sinusoidal, exponential, exponential, linear. Figure 6: the exponential characteristic of the 15 gates, then the exponential characteristic depicted in perspective.

Figure 7: a detail of the internal protection system;

Figures 8 and 9: possible variations of the piston shape. In Figure 9, DV16 - DV15 = Dicsőkkent·

Referring to Figure 1, the oil-powered impact device according to the invention comprises the following main parts: a body 1, a nitrogen-filled high-pressure hydraulic accumulator 2, a piston 3, a sliding control valve 4, a tool 5, a high-pressure supply line 6, an upward lifting space 7 with an upward lifting space line 7a, a low-pressure discharge line 8, a low-pressure volume 9, a hydraulic shock absorber 10, an outlet control gate 11, an annular outlet part 12, a control lower outlet line 13, a control lower outlet line 13a, a control lift damping space 14, control damping gates 15, a thrust space 16, a piston hydraulic shock absorber 18, oil outlet ports 19, 20 secondary power line (also acts as a battery), 21 battery passage openings, 22 overflow valve shown in Figure 7, pre-opening zone of piston B, pre-opening zone of sliding control valve 4, pre-opening zone of piston A, C passage of the upper dynamic seal of the controller, D passage of the lower dynamic seal of the controller, upper dynamic seal of the body E, internal dynamic seal of the body F, G passage of the hydraulic shock absorber, H internal calibrated zone of the controller.

The invention comprises an essential component: a two-chamber accumulator filled with pressurized oil and nitrogen gas and separated by a rubber diaphragm to retain the nitrogen. The oil-filled chamber is connected to the high-pressure line of the hydraulic network and to the middle part of the piston to push the piston upwards. The oil-filled chamber is also connected to the push chamber to which the slide control valve delivers pressurized oil. The pressure in the oil chamber depends on the inlet flow and the impulsive outlet flow.

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-6flow rate. The exit flow is a function of the following parameters:

a) the piston speed upwards, which determines the time for the oil to exit through the outlet network depending on the pressure drop that occurs. The outlet gates are controlled automatically by the top dead center of the sliding control valve modulating the opening;

b) the change in the upward stroke of the piston, which determines the amount of oil in the passive return cycle;

c) the change in the stroke of the sliding control valve, which determines both the top dead center and the stroke of the piston in sequence;

d) pressure peaks in the thrust chamber due to shock waves returning from the piston. The invention eliminates these pressure peaks by opening the exit gate before the impact;

(e) characteristics of the hydraulic deceleration during the final part of the upward movement of the controller;

f) the total duration of the active/passive work cycle.

The control valve, in interaction with the piston, automatically determines the sequential control of the above parameters.

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-7Example

Referring to Figure 1, the slide control valve 4 is in its rest position and the piston 3 is at its bottom dead center. The lower control outlet lines 13 and 13a are closed. Oil flows from the high-pressure supply line 6 through the channel 7a into the upward displacement space 7 and through the high-pressure oil inlet port 11 into the displacement space 16. The oil keeps the nitrogen in the high-pressure oil-gas accumulator 2 under pressure through the accumulator supply line 20 and the passage openings 21. The hydraulic seal of the high pressure towards the low pressure is provided by the connection between the modulator and the body. Under these conditions, the high-pressure supply acts on the piston head 3 and the upward displacement space 7. Given the difference in areas, the high pressure pushes the piston downwards against the reaction of the tool.

At the same time, the high supply pressure acts on the pressure-exposed surface of the slide control valve 4, and its volume 9 is connected via the outlet openings 11 to the outlet line of the slide (sleeve) control valve 8. The difference in the thrust areas together with the difference between the supply pressure and the outlet pressure determines an upward force that lifts the slide control valve 4 up to the maximum permissible stroke; thus, the closing of the oil outlet openings 19 and the opening of the slide volume gate 11 are achieved. At the end of its stroke, the slide control valve 4 is slowed down by a shock absorber 10 and the oil in the space damping the lift of the control 14 is discharged through the control damping gate 15.

Thus, the static pressure in the displacement space 16 is reduced, allowing the upward force of the displacement space 7 to be exerted, initiating the upward movement of the piston 3, as a result of which the remaining oil in the displacement space 16 is discharged through the outlet openings 11 into the outlet conduit 8.

In this phase, the high-pressure oil inlet 19 is closed and the oil coming from the high-pressure inlet line fills the high-pressure oil-gas accumulator 2 through the accumulator supply line 20 and the accumulator feed-through openings 21 up to the dynamic pressure of the supply network.

The piston 3 can rise freely (Fig. 2), enters the sliding control valve 4 and, pushing it towards the damping space 14, determines the downward force of the control valve 4, which is the force acting on the valve 4.

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-8 pushes the valve downwards, as the lower outlet channels of the controller 13, 13a are open.

The dynamic interaction between the reciprocating movement of the piston 3 and the opposing movement of the sliding control valve 4 ends when the sliding control valve 4 (having reached its end position of support) opens the opening 19 and when it re-establishes the passage D of the dynamic seal by closing the outlet openings 11. Oil from the high-pressure supply line 6 enters both the displacement space 16 and the upward displacement space 7 due to the oil being pressurized by the nitrogen in the high-pressure oil-gas accumulator 2. Therefore, the same pressure acts on both the upper part of the piston 3 and the lower part of the upward displacement space 7, which creates a downward force proportional to the difference in the two areas. The resulting force is equal to a sudden downward thrust acting on the piston 3 and providing it with a uniformly accelerated movement.

When the pre-opening zone B of the piston 3 reaches the position A of the sliding control valve 4 earlier than necessary (given the impact position of the tool, which previously blocked the control outlet lines 13, 13a), it eliminates the A/B dynamic passage and allows the high-pressure active oil to fully pressurize the sliding control valve 4, which opens the space 9 at low pressure. The area exposed to pressure of the low-pressure volume 9 of the sliding control valve 4 is multiplied by the difference between the pressures developed in the high-pressure oil-gas accumulator 2 and the pressures developed in the outlet volume 9, which determines a force proportional to the pressure developed in the space 16. This force starts the control upwards, closing the opening 19 in the direction of the space that dampens the lift of the control 14.

The sliding control valve 4 converts kinetic energy by entering the control lift damping space 14 at high speed, creating dynamic passages E, F, pressurizing the control lift damping space 14 and partially opening the sliding volume gates 11, forcing the oil (enclosed in volume 14) to flow through the gates 15 with an exponential type control characteristic.

If the dynamic pressure in volume 16 is very high, after the oil in volume 14 has been completely drained, the sliding control 4

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-9 valve stops at the top dead center. On the other hand, if the dynamic pressure generated is very low, the sliding control valve 4 ends its stroke as soon as it enters the space 14 and begins to pressurize it. Similarly, if the sliding control valve 4 is more heavily loaded, the sliding space 11 will open a larger part of the outlet openings, defining a lower hydraulic resistance to the discharge; the piston 3 will accelerate the discharge of the de-energized oil through the lower outlet openings 11 due to the lower pressure difference. Therefore, by reducing the discharge time, the pressure in the high-pressure oil-gas accumulator 2 decreases.

It is very important to have a certain degree of precision in defining the geometry of the fluid dynamic passages in order to optimize the fine adjustment and timing of the sliding control valve 4. The aim is to avoid areas of different speed: successive pressure changes can affect the time constant of the control system. Therefore, it is necessary to optimize the path taken by the oil through the annular gate and then in the defined thrust space 16.

The truncated conical head of the piston 3 forms an inlet gap with the internal arc and conical base of the sliding control valve 4 (Fig. 4). The purpose of this particular geometry is to convert the kinetic energy of the fluid into direct pressure energy in real time, which immediately moves the sliding control valve 4. The fluid then passes through the volume control gates 11, modulating the stop point of the control. These gates 11 can have different shapes, as shown in Fig. 5: circular, rectangular or trapezoidal in cross-section, according to the applicable law.

Similarly, the outlet gates 15 (Fig. 6) defining the location of the variable top dead center of the sliding control valve 4 can also be of different shapes. The control characteristic of the gates as a function of the rise is usually of the exponential type. For short strokes, linear type control (adjustments) can be used, significantly simplifying the design and with lower accuracy of control of the top dead center of the modulator.

In another preferred embodiment of the impact machine, the machine has a hydraulic shock absorber 10 which protects the sliding control valve 4 from mechanical stress. It prevents

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-10to prevent the 4 sliding control valve from accidentally colliding. After the 4 sliding control valve has risen to its upper position, the highest top dead center of the 4 sliding control valve and the 10 collision-damping space between the C and G passages allow the inertial energy of the control to be converted into thermal energy.

In a further embodiment of the impact device, there is an internal protection system inside the machine (Figure 7) in order to keep the internal operating pressure at a defined level and thus the impact energy of the piston on the tool within the mechanical strength limit determined in the design phase.

The internal protection system is activated in the event of an abnormal operation of the hydraulic network, resulting in excessive flow or unexpected fluctuations.

As already described, the control characteristic of the flow control gates 14 leading to the sliding chamber 16 is exponential, therefore the time constant is reduced so that the sliding control valve 4 receives the maximum lift in the shortest possible time, thereby promoting the operating condition with maximum displacement (maximum consumption of process oil). Therefore, the control lift damping chamber 14 of the sliding control valve 4 is provided with a second, open/close type control, which can operate in extreme cases. This second circuit has a simple bypass line, directly connected to the accumulator and an overflow valve 22, the main role of which has been described and shown in Figure 7.

Finally, two important aspects should be pointed out for the correct sizing of the invention: the first is that the impact efficiency increases with the impact speed, and the second is that the impact speed, since the piston acceleration is constant, increases with the piston stroke. It is also known that the impact energy is proportional to the square of the impact speed, therefore, the above must be taken into account in the design phase, the value of the piston stroke must be kept within certain predetermined requirements.

The consequence of this is that the active diameter of the piston (DV16) for thrust, which is directly affected by the high pressure, must be reduced proportionally.

The impact device can be modified to different models and sizes, while maintaining the same operating principle.

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-11 Figures 8 and 9 show two variants of the geometry of the piston 3 in which the active pusher diameter is reduced.

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Claims (3)

-12PATENT CLAIMS 1. Oil-powered impact device comprising a body (1) in which there is a piston (3) which converts the hydraulic energy of the supply network into mechanical energy, a tool (5) which transmits the mechanical energy, channels (7a), (20), (6), control openings (19), (11), (15), control and thrust spaces (7, 16) which allow the process of converting the hydraulic energy of an incompressible fluid (e.g. oil) into mechanical energy to be carried out; including a high-pressure hydraulic accumulator (2) filled with nitrogen, which has the function of storing the hydraulic energy supplied by the supply channel (6) and returning it to the piston (3); this device being characterised in that it comprises a control slide valve (4) which maintains the operating pressure at a constant value; This mechanism controls the movement of the piston, its active displacement and the oil inlet and outlet control ports (19), (11). 2. An oil-powered impact device according to claim 1, characterized in that it does not require either flow rate control, pressure limiting and regulating valves controlling the operating pressure and/or active and/or passive displacement, or mechanical stops of the piston stroke. 3. A sliding control valve (4) of an oil-powered impact device, characterized in that its movement is solely by the effect of oil dynamics and hydraulic interaction with the piston (3). A sliding control valve according to claim 3, characterized in that its geometry, its specific shape, together with the inlet openings (15) and outlet openings (11) and the pusher (16) and control (14) spaces play a significant role in changing the stroke, active displacement and operating frequency of the piston (3). P-0171 PCT/IB00/00812 -13A sliding control valve according to claim 3 or 4, characterized in that it automatically controls its own position, using kinetic energy in the control space (14) and in the cavities (E) and (F), wherein the calibrated inner and outer surfaces of the sliding control valve together with the calibrated parts of the body (1) form the cavities (E), (F). A sliding control valve according to any one of claims 3 to 5, characterized in that it can control all operating parameters by which both the pressure and the impact energy in the oil-gas accumulator (2) can be kept at a constant value. An oil-powered impact device according to claim 1 or 2, characterized in that oil passages inside the machine optimize the sensitivity and timing of the sliding control valve (4). An oil-powered impact device according to any one of claims 1, 2 or 7, characterized in that the upper (15) and lower (11) overflow gates are controlled by specific control characteristics. An oil-powered impact device according to any one of claims 1, 2, 7 or 8, characterized in that it comprises a hydraulic impact damper (10) which (when the sliding control valve (4) is near the top dead center) prevents impact between the body (1) and the sliding control valve (4). The operation of an oil-powered impact device according to any one of claims 1, 2, 7, 8 or 9, characterized in that in the event of excessive and unexpected flow rates occurring in the high-pressure hydraulic supply line, an overflow valve (22) is opened to allow the system to reduce the pressure in the accumulator. P-0171 PCT/IB00/00812 11. Operation of an oil-powered impact device according to any one of claims 1, 2, 7, 8, 9 or 10, characterized in that the rapid opening of the outlet openings (11) and the rapid closing of the oil outlet openings (19) in the space (16) prevent energy recovery and thus pressure peaks in the thrust space (16). Instead of the notifier, the authorized person SOMFAI AND PARTNERS INDUSTRIAL LAW LTD. 1137 Bp., Pozsonyi út 38. Dr. Eva Somfai, patent attorney P-0171 PCT/IB00/00812