EP2703651A2 - Pressure accumulator assembly and device with such a pressure accumulator assembly - Google Patents

Abstract

The assembly (1) has two pressure storage units (3, 5) connectable with a hydraulic load (11) i.e. piston cylinder unit (13), and with a supply source (15) i.e. pump (49), at respective fluid sides (9, 17). The storage units are gas-conductively linked with one another at gas sides (19, 21) by a regulation device (25). One of the storage units exhibits a target pressure parameter for the load at a target pressure deviation that exceeds a predetermined value by the regulating device, where the other storage unit remains gas-conductively connected until the deviation falls below the value. The pressure storage units are formed as a diaphragm storage unit and a piston storage unit respectively. An independent claim is also included for a rope tensioning device.

Description

The invention relates to a pressure accumulator arrangement and a device with such a pressure accumulator arrangement.

wobei

p

[Pa] der Druck;

V

[m³] das Volumen;

n

die Stoffmenge;

R_m

die universelle oder molare Gaskonstante; und

T

[K] die Temperatur

sind.Pressure accumulator, in particular hydropneumatic pressure accumulator, are known in the prior art in various embodiments, for. B. as a diaphragm accumulator or piston accumulator or other types. If these pressure accumulators are to be installed in hydraulic systems, a design must be carried out. This is done on the basis of the nominal volume, the working pressures, the bias voltage and the working temperature and taking into account the thermal equation of state (1) for ideal gases $$p*V=n*R_m*T.$$

in which

p

[Pa] the pressure;

V

[m ³ ] the volume;

n

the amount of substance;

R _m

the universal or molar gas constant; and

T

[K] the temperature

are.

This formula can be simplified under the assumptions of a constant amount of substance and a constant volume: $$p/T=\mathit{const}\mathrm{,}$$

Equation (2) is also referred to as the law of Amontons.

Fast charging and discharging can lead to considerable heating of the working fluid. Due to the equation (2), this leads to an increase in pressure and to an increased wear of the membrane in the case of membrane accumulators and thus to a shortened service life.

Another problem is the diffusion of gas from the gas side to the fluid side of the hydro-pneumatic diaphragm accumulator. Although it is known to make a refill in downtime, but this is not provided during operation.

In the past, various proposals have been made to adapt pressure accumulators to the respective requirements in operation. These include selecting a pressure accumulator of suitable nominal volume and sufficient preload, cooling the accumulator during operation, and providing pressure relief valves to avoid damaging overpressures in the pressure accumulator.

Furthermore, there is a requirement in practice to make the capacity of a pressure accumulator and its memory characteristic, which can be expressed in the form of a hysteresis, adaptable to changed conditions during operation.

The invention is therefore based on the object to show a pressure storage arrangement that is more flexible and an extended service life having. Furthermore, it is an object of the invention to show a device with such a pressure storage arrangement.

The first part of the object is achieved by a pressure accumulator arrangement having the features of patent claim 1. An apparatus with such a pressure storage arrangement is shown by claim 11. Advantageous embodiments and further developments of the invention are the subject of the dependent claims.

The pressure accumulator arrangement according to the invention has a hydropneumatic pressure accumulator and a further hydropneumatic pressure accumulator. The one accumulator is on its fluid side with a hydraulic consumer and the other pressure accumulator is connected on its fluid side with a supply source. The two pressure accumulators can be coupled to one another gas-conducting on their gas sides by means of a regulating device. The further pressure accumulator remains, a target pressure specification for the hydraulic consumer compliant, connected at a predeterminable value exceeding Solldruckabweichung by means of a regulating device to the one pressure accumulator gas-conducting at least until the target pressure deviation falls below the predetermined value.

By the pressure accumulator assembly according to the invention, it is for the first time advantageously possible to adjust the gas filling of a hydropneumatic accumulator during operation. In this way, the capacity can be changed depending on the situation, ie increased or decreased. By draining gas on the gas side, the capacity can be reduced. If the pressure accumulator has heated up as a result of many charge and discharge cycles, it may be that the permissible operating pressure is reached or exceeded. By discharging the gas from the gas side, it is then advantageously possible to reduce the operating pressure. If the accumulator has cooled down again, it can be refilled of gas on the gas side, the pressure in the accumulator can be increased again. Consequently, then again more pressure can be cached in the accumulator. Thus, the hydraulic system can continue to operate and must not be shut down due to exceeding the capacity of the pressure accumulator. It is also possible, within the scope of the pressure accumulator arrangement according to the invention, to use pressure accumulators with a smaller nominal volume than hitherto.

Advantageously, the target pressure specification can be predetermined in the form of a pressure value or a pressure range. Then the accumulator assembly to the respective hydraulic system in which it is installed, even more flexible customizable. Thus, the pressure in the accumulator can be kept at a certain value or in a certain range of values, which enables optimum operation of the hydraulic consumer.

In addition, the desired pressure specification can be predetermined in a time-dependent manner. Consequently, the adaptation of the pressure accumulator arrangement can be made to changing requirements during operation.

The permissible operating pressure of one pressure accumulator is expediently below the permissible operating pressure of the further pressure accumulator. Furthermore, the nominal volume of one accumulator can be less than the nominal volume of the further accumulator. These features advantageously ensure that an increase in capacity can take place in any operating state of the one pressure accumulator.

The one pressure accumulator is advantageously a diaphragm accumulator while the other pressure accumulator is expediently a piston accumulator. Thus, the accumulator assembly is optimally adaptable to its intended use at a low cost. As a result, lower energy losses occur in membrane accumulators due to the low intrinsic weight of the membrane during rapid charge and discharge cycles. In addition, faster cycles can be driven become. On the other hand, the piston accumulator has a higher permissible pressure ratio with the same volume, making it ideal for filling a diaphragm accumulator with gas or relieving it of gas.

Particularly advantageous is at least one sensor, in particular a pressure sensor or a temperature sensor, connected to the one pressure accumulator or to the further pressure accumulator or to the connecting line between the pressure accumulators. The sensors allow the operational monitoring of the pressure accumulators and allow the capacity to be adapted to the respective operating state even more quickly and in line with demand.

In a further, preferred embodiment, the additional pressure accumulator can be connected alternately to the supply source or a tank at its fluid side via a valve. This makes it possible to additionally bias or relieve the further accumulator depending on how the specific operating situation requires it. In this way, the capacity of the further pressure accumulator and thus the accumulator assembly can be adjusted overall in a wider context.

Furthermore, a connection for filling the gas filling of a pressure accumulator may be provided. This connection can be refilled especially during downtime. The filling may be required in particular due to the diffusion of gas through the membrane of the membrane memory.

The second part of the object is achieved by a device according to claim 11, the device has an accumulator assembly, wherein the one pressure accumulator is coupled to a piston-cylinder unit as a hydraulic consumer. Such a device can be used in particular as a cable tensioner in cranes or lifts.

It can be a sensor, in particular a temperature, pressure or position sensor, provided on the piston-cylinder unit. The sensor may then be coupled to the regulating device. This allows a particularly accurate and timely adjustment of the capacity of the accumulator assembly during operation. Due to the distance between the piston-cylinder unit and the accumulator assembly can thus be reacted earlier and more appropriate to the needs and there may be a more targeted adaptation to the particular requirements in the piston-cylinder unit.

The piston-cylinder unit may be connectable to the supply source, preferably via a valve, which is preferably formed as a 3/2-way valve or flow divider valve. This embodiment enables positioning of the piston in the piston-cylinder unit. Positioning can also be done during operation.

Fig. 1

einen Hydraulikplan der erfindungsgemäßen Druckspeicheranordnung bzw. der Vorrichtung mit einer solchen Druckspeicheranordnung; und

Fig. 2

eine perspektivische Ansicht der Druckspeicheranordnung.

The invention is explained in more detail with reference to exemplary embodiments illustrated in the figures. Show it:

Fig. 1

a hydraulic plan of the pressure accumulator assembly according to the invention or the device with such a pressure accumulator assembly; and

Fig. 2

a perspective view of the accumulator assembly.

In the Fig. 1 and 2 a pressure accumulator assembly 1 with a hydropneumatic pressure accumulator 3 and a further hydropneumatic pressure accumulator 5 is shown. The one pressure accumulator 3 is connected to form the device 7 on its fluid side 9 with a hydraulic consumer 11 in the form of a piston-cylinder unit 13, see. Fig. 1 , The further pressure accumulator 5 is connected to a supply source 15, in particular with a hydraulic pump, connected on its fluid side 17. The two accumulators 3, 5 are gas-conductively coupled to each other on their gas sides 19, 21 via a connecting line 23 by means of a regulating device 25. The regulating device 25 in this case comprises a switched into the connecting line 23 valve 27 as a blocking member 29. The further pressure accumulator 5 remains, a target pressure specification for the hydraulic consumer 11 compliant, at a predetermined value exceeding Solldruckabweichung means of the regulating device 25 to the other pressure accumulator 5 at least as long gas-conducting connected until the setpoint pressure deviation falls below the predefinable value. Thus, the blocking member 29 is opened when the pressure in a pressure accumulator 3 is higher than the target pressure plus the tolerable Solldruckabweichung and the pressure in the other pressure accumulator 5 is less than in a pressure accumulator 3. In this way, the one pressure accumulator 3 by discharging gas relieved. Conversely, the locking member 29 can be opened when the pressure in a pressure accumulator 3 is less than the target pressure minus the tolerable Solldruckabweichung and the pressure in the other accumulator 5 is greater than in a pressure accumulator 3. Then the accumulator 3 is filled with gas. Advantageously, the target pressure specification may consist of a specific pressure value or a pressure range. The actuation of the blocking member 29 of the regulating device 25 can also be timed via a control unit 31.

The one pressure accumulator 3 is designed as a diaphragm accumulator while the other pressure accumulator 5 is a piston accumulator. The piston accumulator 5 in this case has an equal or higher nominal volume and an equal or higher permissible operating overpressure with respect to the diaphragm accumulator 3. For monitoring of a pressure accumulator 3 is a pressure sensor 32 to the connecting line 23 between the gas side 19 of a pressure accumulator 3 and the locking member 29 of the regulating device 25 connected. Furthermore, a connection 35 for filling the gas side 19 of a pressure accumulator 3 is provided in this section 33 of the connecting line 23. The connection of the fluid side 17 of the further pressure accumulator 5 to the supply source 15 via two switching valves 37, 39, which are designed as electromagnetically operable directional control valves. The one valve 37 couples a supply line 41 at one end 43 either to the further pressure accumulator 5 or the hydraulic consumer 11. This valve 37 allows fluid either the fluid side 17 of the further pressure accumulator 5 or a piston side 45 of the piston-cylinder unit thirteenth be forwarded. The second valve 39 couples the other end 47 of the supply line 41 either with the supply source 15 in the form of a pump 49 or with a tank 51. Thus, hydraulic fluid can be conveyed not only to the further pressure accumulator 5 and the hydraulic consumer 11, but also in the reverse direction drain to the tank 51.

At the piston accumulator 5 and the cylinder 53 of the piston-cylinder unit 13 further pressure sensors 55, 57 are provided. In addition, 35 temperature sensors 59, 61, 63 are arranged on the cylinder 53 and the pressure accumulators. For monitoring the position of the piston 65, a position sensor 67 is attached to the piston-cylinder unit 13.

The control unit 31 is coupled to the valves 27, 37, 39 and the sensors 32, 55, 57, 59, 61, 63 of the device.

In Fig. 2 the accumulator assembly 1 is shown in a perspective view. One pressure accumulator 3 is connected in the form of a diaphragm accumulator to a valve housing block 69. At the opposite end of the valve housing block 69, a piston accumulator is arranged as a further pressure accumulator 5. The valve housing block 69 is cuboid and solid designed to withstand even very high pressures. In the valve housing block 69, the connecting line between the two pressure accumulators 3, 5 and the intermediate valve 27 of the regulating device 25 is arranged. Furthermore, the valve housing block 69 has a connection 35 for filling the gas side of the one pressure accumulator 3. In addition, there is a connection 71 for a sensor for detecting the pressure in the connecting line between the gas side of a pressure accumulator 3 and the valve 27. The accumulator assembly 1 is designed to save space.

Thus, a way is shown by the accumulator assembly 1 and the device 7 with the accumulator assembly 1, on which the capacity of a pressure accumulator 3 by changing the amount of material on the gas side 19 of a pressure accumulator 3 during operation is customizable. The range of application of the accumulator assembly 1 is thus increased or it is the installation of a smaller pressure accumulator 3 allows.

Claims (13)

Pressure accumulator arrangement with a hydropneumatic pressure accumulator (3) and a further hydropneumatic accumulator (5), one accumulator (3) with a hydraulic consumer (11) and the further pressure accumulator (5) with a supply source (15) on the respective fluid sides (9 , 17) are connectable, wherein the two pressure accumulator (3, 5) on its gas sides (19, 21) by means of a regulating device (25) are gas-conductively coupled together, the further pressure accumulator (5), a target pressure specification for the hydraulic consumer (11 ) adhering, at a predetermined value exceeding the desired pressure deviation by means of a regulating device (25) to the one pressure accumulator (3) remains gas-conducting at least until the target pressure deviation falls below the predefinable value. Pressure accumulator arrangement according to claim 1, characterized in that the desired pressure preset in the form of a pressure value or a pressure range can be predetermined. Pressure accumulator arrangement according to one of the preceding claims, characterized in that the target pressure specification can be predetermined time-dependent. Pressure accumulator arrangement according to one of the preceding claims, characterized in that the permissible operating overpressure of the one pressure accumulator (3) is below the permissible operating overpressure of the further pressure accumulator (5). Pressure accumulator arrangement according to one of the preceding claims, characterized in that the nominal volume of the one Pressure accumulator (3) is below the nominal volume of the further pressure accumulator (5). Pressure accumulator arrangement according to one of the preceding claims, characterized in that the one pressure accumulator (3) is a diaphragm accumulator. Pressure accumulator arrangement according to one of the preceding claims, characterized in that the further pressure accumulator (5) is a piston accumulator. Pressure accumulator arrangement according to one of the preceding claims, characterized in that at least one sensor (32, 55, 61, 63), in particular a pressure sensor or a temperature sensor, to the one pressure accumulator (3) or to the further pressure accumulator (5) or to the connecting line (23) between the pressure accumulators (3, 5) is connected. Pressure accumulator arrangement according to one of the preceding claims, characterized in that the further pressure accumulator (5) on its fluid side (17) via a valve (39) alternately to the supply source (15) or a tank (51) can be connected. Pressure accumulator arrangement according to one of the preceding claims, characterized in that a connection (35) for filling the gas filling of a pressure accumulator (3) is provided. Device with a pressure storage arrangement according to one of the preceding claims, wherein the one pressure accumulator (3) is coupled to a piston-cylinder unit (13) as a hydraulic consumer (11). Apparatus according to claim 12, characterized in that at least one sensor (57, 59, 67), in particular a temperature, pressure or position sensor, on the piston-cylinder unit (13) is provided and that the sensor (57, 59 , 67) is coupled to the regulating device (25). Apparatus according to claim 12 or 13, characterized in that the piston-cylinder unit (13) to the supply source (15) is connectable, preferably via a valve (37), the further preferred as a 3/2-way valve or flow divider valve is trained.

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