Method for determination of expansion of the hydraulic prop, particularly in self-advancing supports

(12) PATENT DESCRIPTION (19) PL (11) (13) B1 (21) Application number: 36363⁰ (^{5)) lntC1}·

E21D 15/46 (2006.01) G01L 15/00 (2006.01) (22) Date of notification: 21/11/2003

Method of determining the expansion state of a hydraulic support, especially a stand of a mining powered support

<td>(43) Application announced: May 30, 2005 BUP 11/05</td><td>(76) Authorized and inventor: Bednarz Ryszard, Katowice, PL Diederichs Ryszard, Katowice, PL Kwiecińska Danuta, Bytom, PL Ożóg Leon, Bytom, PL</td>

<td>(45) The grant of the patent was announced: March 31, 2009 WUP 03/09</td><td>(74) Representative: Caban Włodzimierz, INVENT Sp. z o. o</td>

(57) 1. The method of determining the expansion state of a hydraulic support, in particular the stand of a mining powered support, according to which the working spaces of this support during its normal compression work are closed by means of check valves, preferably controlled, characterized in that during normal operation of the support (1) continuous compression compares the pressures of the hydraulic medium in the head space (3) and the piston space (2) of the support (1), and the result of this comparison is displayed on the indicator (8) corresponding to this hydraulic support (1).

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Description of the invention

The subject of the invention is a method for determining the expansion state of a hydraulic support, in particular a mining propeller support stand, applicable in underground mining.

In the previous mining practice, the determination of the expansion state of the props of the powered support is mainly carried out by measuring the pressure of the hydraulic medium in the plunger space of the props with the use of built-in pressure gauges. In the specific conditions of the mining excavation environment, reading the manometers of individual hydraulic props is particularly difficult due to poor lighting and widespread dusting of elements with airborne dust. In addition, the interpretation of the read indications is not unequivocal and does not allow for a specific diagnosis of possible hydraulic support malfunctions. There may be a situation where, in the absence of leaks to the outside of the stand of the hydraulic medium and with a small, hardly noticeable drop in pressure in the piston space, the stand does not work with the assumed support, posing a huge threat to the crew employed in the wall. The most common cause of this state of affairs is the damage to the core box seal in the stand cylinder, causing the medium to pass from the under piston space to the over piston space, from where in the normally used hydraulic systems of powered supports, the medium is discharged directly to the drainage line. In the conditions of using additional charging of the props, resulting in a periodic supply of a medium with high pressure to the under-piston space in the event of a pressure reduction, the readings from the manometer do not give the correct image in terms of the actual support of the rack. This situation leads to significant losses of the hydraulic medium under high pressure, as the supplied medium goes to the overflow, and the stand with a damaged inner seal does not meet the assumed parameters.

There are also known, for example, from the Polish patent description No. PL 139 887, solutions for power supply systems for hydraulic props, in which, in order to avoid multiplication of the pressure of the hydraulic medium in the head space, the outflow branch is equipped with a controllable check valve and a safety valve. This solution is designed for a specific arrangement of powered support stands and is intended to protect only the stands located on the backside of the powered support section, which can take tensile loads instead of the normally occurring compressive loads. In the case of loading the racks only with external compressive forces, such systems have not been used so far.

There is also known, for example, from the Polish patent description No. PL 191 201, a device for controlling the slippage of hydraulic supports for mining supports, whose task is to visualize the compressive loads acting on the support, forcing the support to slide down.

In another solution, known, for example, from the Polish patent application P-307412, the operational support indicator of the hydraulic stand has a lamp controlled by a through-valve connected to the high-pressure space of the stand. Providing a certain image of the support operation, such devices do not determine the actual support of the stand, which is a function of many factors influencing the stand.

The aim of the invention is to develop such a method of determining the expansion state of a hydraulic support, in particular a mining stand of a powered support, which will enable the current control of the actual working support of a hydraulic support, while simultaneously indicating the condition of the internal seals of the support, thus meeting the safety requirements for powered mining supports.

The essence of the invention consists in the fact that during normal operation of the compression support, the pressures of the hydraulic medium are continuously compared in the spaces of the over-piston and under-piston support with closed outflows from these spaces, and the result of comparing these pressures is shown on the indicator corresponding to the hydraulic support.

It is advantageous, and at the same time sufficient in practice, to perform the method in which the result of comparing the pressures in the chambers of the over-piston and under-piston support is displayed in the assumed ranges of its values, which simplifies the work of the operator controlling the operation of the housing and allows him to make quick decisions regarding the control of the housing.

In order to adapt the method according to the invention to the changing mining conditions in the excavation, it is possible to implement it in which the ranges of the values ​​of the pressures to be compared are set individually for each hydraulic support.

PL 201 259 B1

In such a situation, it is expedient to assign a separate color to the indicator for each range of values ​​of the pressures of the hydraulic medium, as this allows the operator to be easily observed from the safety-related distance.

For the basic use of the method, it is advantageous if the external indicator is permanently installed on the hydraulic support, as it allows for continuous observation of the support state of each of the struts operating in the excavation without any additional actions.

In the simplified version, however, it is possible for the external indicator to be detachably mounted on the hydraulic support, which will enable separate control of selected supports, the operation of which will be objected to by the operator of the housing.

The main advantage of the method according to the invention is obtaining the current, required by safety regulations, control of the spreading and operation of the powered support, while obtaining full credibility of the observation.

An additional advantage is that the observations can be made from a relatively large distance, guaranteeing the full safety of the operator maneuvering the housing. At the same time, the method according to the invention makes it possible to plan repairs and replacement of hydraulic supports, which results, for example, from the assumed value ranges of the results of the compared pressures and assigning separate colors to these ranges indicated by the indicator. Having such indications, the operator knows which supports should be replaced, which should be replaced in a short time, and which supports work with the required parameters.

It is also not without significance that each person in the excavation is informed about the possible risk in a specific place of the excavation. It is also important that the method is based on technical solutions of hydraulic systems in normal use, which significantly reduces the costs of this use.

The invention is explained in more detail in an application example in accordance with the schematic sketch of the hydraulic strut attached in the drawing.

The hydraulic strut 1 has an under-piston space 2 and an over-piston space 3 separated by a piston 4 of a retractable core box 5. The strut 1 is spread by supplying the hydraulic medium under high pressure to the under-piston space 2 through a controlled check valve assembly 6, and the super piston space 3 connects to the drainage main through the assembly controlled check valve 7. After reaching the assumed pressure in the plunger space 2, which guarantees the expansion of the hydraulic support 1 with the desired bearing capacity, the normal operation of this support for compression begins, resulting from the transfer of loads acting on the support, resulting from the pressure of the rock mass, by this support 1. In this phase of operation of the hydraulic support 1, with the controlled check valves 6 and 7 closed, the pressures of the hydraulic medium in the under piston 2 and over the piston 3 spaces are continuously compared by means of an external indicator 8 connected both to the piston space 2 and to the post piston space 3. Under the conditions of correct operation of the support 1, the pressure in the under-piston space 2 will increase, while in the over-piston space 3 the pressure will not increase, which will be shown by the indicator 8 with the appropriate color of the indication.

In the event of a relatively small leakage of the piston 4, the pressure in the head space 3 will slowly and successively increase, and if the result of comparing the pressures in the head space 3 and under the piston 2 exceeds the assumed threshold, it will be shown on the indicator 8 by the change of the color of the indication. With a significant leakage of the piston 4, the pressure in the over piston space 3 will increase rapidly, which will result in relatively quick exceeding the assumed value threshold of the compared pressures, and as a result the indicator 8 will illustrate this state of affairs with a different color. The operator controlling the powered support by observing the indications of the indicator 8 of each support 1 can draw conclusions on an ongoing basis as to the technical condition of the hydraulic supports 1 of the individual sets of powered support. If the indicators 8 are equipped with lighting elements with different display colors for individual thresholds, the operator will be visually aware of the condition of each hydraulic support 1 within his sight, which will enable him to react on an ongoing basis, appropriate to the current situation in the longwall working.