DE4320383A1 - Method for measuring the current gas bias pressure in a hydropneumatic store - Google Patents

Abstract

The invention relates to a method for measuring the current gas bias pressure poact of a gas which can be accommodated in a hydropneumatic store 10, in which a gas-conveying connection 18 is produced between the store 10 and a chamber 16 which has a fraction of the storage volume and can be closed off by means of a closing device 24. As a result of the fact that, by means of a pressure value pick-up 22 arranged between the store 10 and the closing device 24, the gas pressure px in the store 10 is measured with a closed-off connection and, after opening the connection 18, the accompanying pressure change py is measured, and the fact that the current gas bias pressure poact is determined from the pair of pressure values px, py obtained in this manner, the actual gas bias pressure in the case of a hydropneumatic store can be reliably and accurately registered using means of simple construction and using only one single measuring process and, consequently, a statement can be made as to the operating condition of the store. <IMAGE>

Description

The invention relates to a method for measuring the actual gas bias pressure of one in a hydropneumatic accumulator Recordable gas in which a gas-conducting connection between the memory and a fraction of the memory volume mens having produced by means of a Shut-off is shut off.

In hydropneumatic storage, it is necessary to use the gas voltage, the intended operation of such Memory is required at certain intervals to control, as usually depended on gas losses the operation of the memory is to be expected. For this it has been necessary so far, the corresponding Hydraulic system on the so-called oil side completely depressurised too at least the part of the plant that the Hydrospeicher concerned, then in this unpressurized state the Gas bias pressure of the located in the hydraulic accumulator  Gas, mostly nitrogen gas, to check and if necessary refill. This process is time consuming and the hydro storage facility is in the period of review out of order.

In EP 0 447 791 A2 is to comply with a predefinable Pressure setpoint for hydropneumatic accumulators already have been proposed at a measuring provided for this purpose temporarily a gas-exchanging connection between the memory and only a fraction of the Speichervolu mens having measuring chamber, which via a pressure has measuring device. Is the determined in the measuring chamber Actual pressure value in the known method smaller or larger as the pressure setpoint, is via a with the measuring chamber identical dosing the filling or emptying with a predeterminable dosage carried out, the gas-leading Connection by means of the shut-off cyclically each is released or blocked. It has been shown that this known solution does not work satisfactorily and leads in particular to measurement errors. Further, this solution is both in operation and in the production and Überwa complicated and expensive.

Based on this prior art, the invention is the Task based, a method as well as after the procedure working device for measuring the actual gas bias to create pressure in a hydropneumatic storage, so that with low cost and monitoring effort is accurate Reach measurement results. This task triggers a procedure ren with the features of claim 1 and one after this Procedure working device.

Characterized in that by means of a between the memory and the Shut-off arranged pressure sensor at abge blocked connection the gas pressure in the store as well as after opening the compound measured the associated pressure change is and that from the pressure value pair thus obtained the  Actual gas preload pressure is determined, the actual Gas preload pressure with structurally simple means with only capture a single measurement safely and accurately and therefore make a statement about the operating state of the memory. The measurement is accurate and can be in any sta tionary operating state of the memory.

Preferably, in this case, the actual gas biasing pressure is after determined by the following formula:

in which
V₀ = gas volume of the memory,
V _A = chamber volume,
px = gas pressure with disconnected connection and
py = gas pressure with open connection to the chamber.

In a preferred embodiment of the invention Method is for the measuring process, the gas in the memory on specifiable volume brought for which the pressure setpoint is known. This further simplifies the process. If the hydropneumatic accumulator is a storage bubble has, is at a relaxed memory bubble, ie at fluid side substantially emptied memory, the measurement featured Taken because for this operating condition, the target pressure to the target pressure before first use of the memory, has been specified by the manufacturer and is therefore known.

In a further preferred embodiment of the invention According to the method, a pressure to relax the chamber balancing connection between the chamber and the environment  produced via the shut-off device. By this closing and thus depressurization of the chamber this is prepared for a new measurement process.

In a particularly preferred embodiment of the invention The process of the invention is at an actual gas bias pressure that is less than or equal to a desired Gasvorspan tion pressure, the memory with a predetermined amount of gas filled or emptied via a metering device. Since the Memory over its intended duration of operation in the Usually loses gas, the metering device in the form be formed of a refilling device for the gas. Should however, there is an unintentional overfilling with gas or The memory should be used for a different purpose have lower gas bias, the metering device also serve to excess gas after making a Drain measurement accordingly.

The device for carrying out the method according to the invention rens has the chamber, which is part of a Aufsetzvorrichtung is the gas side can be connected to the memory, wherein the Shut-off device from a stopcock or solenoid valve is formed. As a result, the device can be in wesentli chen in one piece and save space on the memory put on. Preferably, in this case, the stopcock Shut-off with three connections on, in the locked position connect the chamber with the environment and those in the open position, connect the chamber to the storage tank on the gas side.

In the following, the inventive method is based on a Device that works according to this method and that in the single figure is shown, explained in more detail.  

A designated as a whole with 10 hydropneumatic SpeI cher, for example in the form of a membrane or Blasenspei chers, has a gas valve body 12 . About this Gasven tilkörper 12 , the memory 10 can be filled with a working gas, for example in the form of nitrogen. These storage arrangements are well known in the art, so that the memory 10 is shown for reasons of simplification only partially with regard to its gas side in the figure.

The gas valve body has an external thread onto which a fitting device designated as a whole by 14 can be screwed. The set-up device 14 is substantially formed as a rectangular block, and includes at its free end a spherical chamber sixteenth Along the longitudinal axis of the Aufsetzvor device 14 extends in the same a straight-line connection in the form of a channel 18 , the ends in the chamber 16 and into the interior of the gas valve body 12 and thus into the interior of the memory 10 .

Facing the gas valve body 12 opens into the channel 18, a pressure-conducting cross-connection 20 , which is extended to the outside of the Aufsetzvorrichtung 14 in diameter and provided with a thread over which a Druckwertaufneh mer 22 can connect to the attachment device 14 . Gas pressure measuring pressure transducer are well known, so that will not be discussed in detail hereon. The pressure transducer 22 may be connected to a computer unit (not illustrated), which provided with an appropriate software automatic conversion and thus allows automatic monitoring of the operating state of the memory 10 . Via an appropriate display device (not shown) can then be directly the actual Gasvorspan design pressure po _is read and beyond a cyclic remote monitoring of the memory is possible with the computer unit.

Between the chamber 16 and the terminal 20 of the Druckwertauf receiver 22 is in the channel 18 within the Aufsetzvorrich a shut-off device 24 connected in a known manner via a lever (not shown) or via an electrically controllable actuator (not shown) is actuable tigbar , The stopcock 24 has a plug 26 which forms the shut-off part of the shut-off device and which is provided with three connections 28 arranged in a T-shape with respect to one another. Upon actuation of the stopcock 24 , so when turning the plug 26 , from the position shown in the figure entge counterclockwise, the illustrated in the figure upper port 28 opens into a side channel 30 , which opens into the open.

In the position shown in the figure of the stopcock 24 with chicks 26 , the shut-off device is shown in its open Stel development, in which the chamber 16 is connected to the gas side of the memory 10 . In the blocking position (not shown), in which the plug 26 is rotated counterclockwise, a pressure-conducting connection between the chamber 16 and the environment via the side channel 30 is Herge. Instead of the stopcock 24 and an elec- trically actuated solenoid valve (not shown), for example, in the form of a 3/2-way valve, could occur.

In the method according to the invention the shut-off cock 24 is first brought into its blocking position and measured by means of the front of the shut-off pressure transducer 22 of the gas pressure px in the memory. In a further step, the shut-off device is brought into its open position, wherein the stopcock 24 assumes a position according to the figure. The chamber 16 is then switched on and there is a pressure drop in the system (memory 10 , mounting device 14 ), wherein the concomitant pressure change py Festge in a new measuring step by the pressure transducer 22 is set. From the pressure value pair px and py thus obtained, the actual gas preload pressure po _{ist is then} determined, preferably with the mentioned computer unit, according to the following formula:

in which
V₀ = gas volume of the memory,
V _A = chamber volume,
px = gas pressure with disconnected connection and
py = gas pressure with open connection to the chamber.

As the following calculation example shows, can then from the given storage gas volume V₀ and the given Kammervo lumen VA and the obtained Meßdruckwerten px and py the actual gas bias pressure po _is :
given:

Storage gas volume V₀ = 50 l chamber volume V _A = 0.5 l gas pressure px = 300 bar gas pressure py = 295 bar

po _is = 180 bar.

Now, if the thus determined actual gas bias pressure po _is smaller or greater than the target gas bias pressure po _soll for this memory 10 , the memory with the corresponding amount of gas to fill or empty. Here, one possibility is to remove the attachment device 14 and then to fill the memory 10 in a conventional manner or to empty. It is more advantageous, however, to leave the placement device 14 on the storage 10 and via a metering device (not shown) and via a further side channel 32 of the placement device 14 , which opens at the height of the cross-connection 20 in the channel 18 and which is closed accordingly, make the refilling or emptying.

Is a measurement completed, then the chamber 16 is relaxed, thus made depressurized by a pressure-conducting connection by means of the shut-off device via the stopcock 24 between the side channel 30 and the chamber 16 is made. Instead of a spherical configuration of the chamber 16 , another embodiment in the manner of an outwardly closed cavity is possible.

Claims (7)

1. A method for measuring the actual Gasvorspannungsdruckes _(po) of a hydropneumatic accumulator recordable (10) gas, wherein a gas-carrying connection (18) having between the memory (10) and a a fraction of the storage volume chamber (16) was prepared Is, which can be shut off by means of a shut-off device ( 24 ), characterized in that by means of a between the memory ( 10 ) and the shut-off device ( 24 ) arranged pressure sensor ( 22 ) with the connection shut off the gas pressure (px) in the memory ( 10 ) and after opening the connection ( 18 ) the associated pressure change (py) is measured and that from the pair of pressure values (px, py) thus obtained the actual gas pressure voltage (po _ist ) is determined. 2. The method according to claim 1, characterized in that the actual gas preload pressure (po _is ) is determined according to the following formula: in which
V₀ = gas volume of the memory,
V _A = chamber volume,
px = gas pressure with disconnected connection and
py = gas pressure with open connection to the chamber. 3. The method according to claim 1, characterized in that for the measuring operation, the gas in the memory ( 10 ) is brought to a predeterminable volume, for which the desired pressure value (po _soll ) is known. 4. The method according to any one of claims 1 to 3, characterized in that for relaxing the chamber ( 16 ) a pressure equalizing connection ( 30 ) between the chamber ( 16 ) and the environment via the shut-off device ( 24 ) is produced. 5. A method according to any one of claims 1 to 4, characterized in that in an actual Gasvorspannungsdruck _(po) is greater than the less than or equal pressure to a target Gasvorspannungs (po _soll), the memory (10) with a predetermined amount of gas is filled or emptied via a metering device. 6. Apparatus for carrying out the method according to one of claims 1 to 5, characterized in that the chamber ( 16 ) is part of a placement device ( 14 ), the gas side to the memory ( 10 ) can be connected, and that the shut-off device from a Stopcock ( 24 ) or solenoid valve is formed. 7. The device according to claim 6, characterized in that the stopcock ( 24 ) has a shut-off ( 26 ) with three terminals ( 28 ) which connect the chamber ( 16 ) in the locked position with the environment and in the open position the chamber ( 16 ) on the gas side to the memory ( 10 ).