EP2703651B1 - Device with a pressure accumulator assembly - Google Patents

Description

Device with an accumulator arrangement

The invention relates to a device with a pressure accumulator arrangement having the features in the preamble of claim 1.

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 accumulators, in particular hydropneumatic pressure accumulators, are known in the prior art in a variety of embodiments, e.g. B. as a diaphragm accumulator or piston accumulator or in other designs. If these pressure accumulators are to be installed in hydraulic systems, a design must be made. This is based on the nominal volume, the working pressure, the preload and the working temperature, as well as taking into account the thermal equation of state (1) for ideal gases $$\rho *V=n*R_m*T,$$

whereby 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.

Assuming a constant amount of substance and a constant volume, this formula can be simplified to: $$p/T=\mathit{const}.$$

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

Rapid charging and discharging processes can cause the working fluid to heat up considerably. Based on Equation (2), this leads to an increase in pressure and increased wear on the diaphragm of diaphragm accumulators, and thus to a shorter service life.

Another problem is the diffusion of gas from the gas side to the fluid side of the hydropneumatic diaphragm accumulator. Although it is known that refilling can be carried out during downtimes, this is not intended during operation.

Various proposals have been made in the past to adapt pressure accumulators to the respective operational requirements. These include the selection of a pressure accumulator with a suitable nominal volume and sufficient preload, cooling of the pressure accumulator during operation and the provision of pressure relief valves in order 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 accumulator characteristics, which can be expressed in the form of a hysteresis, adaptable to changed conditions during operation.

the DE 198 30 506 A1 describes a device with a hydraulic consumer, a supply source, a regulating device, a valve, a supply line and a pressure accumulator arrangement with a hydropneumatic pressure accumulator and a further hydropneumatic pressure accumulator, one pressure accumulator being able to be connected to the hydraulic consumer and the other pressure accumulator to the supply source on the respective fluid sides, the two pressure accumulators being able to be coupled to one another in a gas-conducting manner on their gas sides by means of the regulating device, wherein one pressure accumulator is designed to comply with a setpoint pressure specification for the hydraulic consumer, the regulating device being designed to connect one pressure accumulator to the further pressure accumulator in a gas-conducting manner in the event of a deviation from the setpoint pressure specification that exceeds a predeterminable value, at least until the deviation from the setpoint pressure specification exceeds the predeterminable value value falls below.

More devices with a pressure accumulator assembly go from the JP H04-090917 A , the EP 1 134 586 A2 and the JP S60-056617 A out.

The invention is therefore based on the object of demonstrating a device with a pressure accumulator arrangement which can be used more flexibly and has a longer service life.

The first part of the task is solved by a device with the features of patent claim 1 . Advantageous embodiments and developments of the invention are the subject matter of the dependent claims.

According to the characterizing part of claim 1, it is provided that the valve couples the supply line, which can be coupled to the supply source, at one end to either the further pressure accumulator or the hydraulic consumer, and that this valve enables fluid to flow either to the fluid side of the further pressure accumulator or to a piston side of a piston - to feed the cylinder unit.

The pressure accumulator arrangement has a hydropneumatic pressure accumulator and a further hydropneumatic pressure accumulator. One pressure accumulator can be connected to a hydraulic consumer on its fluid side and the other pressure accumulator can be connected to a supply source on its fluid side. The two pressure accumulators can be coupled to one another in a gas-conducting manner on their gas sides by means of a regulating device. The additional pressure accumulator remains connected to the pressure accumulator at least until the desired pressure deviation falls below the predeterminable value if the desired pressure deviation exceeds a predeterminable value.

The pressure accumulator arrangement makes it advantageously possible for the first time to adapt the gas filling of a hydropneumatic pressure accumulator during operation. In this way, the capacity can be changed, i.e. increased or decreased, depending on the situation. Venting gas on the gas side can reduce capacity. If the pressure accumulator has heated up significantly as a result of many charging and discharging cycles, the permissible operating pressure may be reached or exceeded. By releasing the gas from the gas side, it is then advantageously possible to reduce the excess operating pressure. When the accumulator has cooled down again, the pressure in the accumulator can be increased again by refilling gas on the gas side. Consequently, more pressure can be temporarily stored in the pressure accumulator again. The hydraulic system can therefore continue to be operated and does not have to be switched off because the capacity of the pressure accumulator has been exceeded. It is also possible to use pressure accumulators with a smaller nominal volume than before as part of the pressure accumulator arrangement.

The target pressure specification can advantageously be specified in the form of a pressure value or a pressure range. The pressure accumulator arrangement is then even more flexible in relation to the particular hydraulic system in which it is installed customizable. Consequently, the pressure in the pressure accumulator can be kept at a specific value or within a specific range of values, which enables optimal operation of the hydraulic consumer.

In addition, the target pressure specification can be specified as a function of time. Consequently, the pressure accumulator arrangement can be adapted to changing requirements during operation.

The permissible operating pressure of one pressure accumulator is expediently below the permissible operating pressure of the other pressure accumulator. Furthermore, the nominal volume of one pressure accumulator can be below the nominal volume of the other pressure accumulator. These features advantageously ensure that the capacity can be expanded in any operating state of one pressure accumulator.

One pressure accumulator is advantageously a diaphragm accumulator, while the other pressure accumulator is advantageously a piston accumulator. The pressure accumulator arrangement can thus be optimally adapted to its intended use at low cost. With membrane accumulators, for example, there are lower energy losses due to the low weight of the membrane during fast charging and discharging cycles. In addition, faster cycles can be run. In contrast, the piston accumulator has a higher permissible pressure ratio for the same volume and is therefore ideally suited for filling a diaphragm accumulator with gas or relieving it of gas.

At least one sensor, in particular a pressure sensor or a temperature sensor, is particularly advantageously connected to one pressure accumulator or to the further pressure accumulator or to the connecting line between the pressure accumulators. The sensors make it possible to monitor the operation of the pressure accumulator and allow the capacity to be adjusted even more quickly and in line with requirements to the respective operating status.

In another preferred embodiment, the fluid side of the additional pressure accumulator can be connected alternately to the supply source or to a tank via an additional valve. This makes it possible to additionally preload or relieve the additional pressure accumulator, depending on how the specific operating situation requires it. In this way, the capacity of the additional pressure accumulator and therefore of the pressure accumulator arrangement as a whole can also be adjusted within a wider range.

Furthermore, a connection for filling up the gas side of one pressure accumulator can be provided. This connection can be used to refill, especially during downtimes. The filling may be necessary in particular due to the diffusion of gas through the diaphragm of the diaphragm accumulator.

A sensor, in particular a temperature, pressure or position sensor, can be provided on the piston-cylinder unit. The sensor can then be coupled to the regulator. This enables a particularly precise and timely adjustment of the capacity of the pressure accumulator arrangement during ongoing operation. Due to the distance between the piston-cylinder unit and the pressure accumulator arrangement, it is therefore possible to react earlier and more appropriately, and a more targeted adaptation to the respective requirements in the piston-cylinder unit can take place.

The piston-cylinder unit can be connected to the supply source via the valve, which preferably as a 3/2-way valve or flow divider valve is formed. This embodiment enables the piston to be positioned in the piston-cylinder unit. The positioning can also take place during ongoing operation.

Fig. 1

einen Hydraulikplan der Vorrichtung mit einer Druckspeicheranordnung; und

Fig. 2

eine perspektivische Ansicht der Druckspeicheranordnung.

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

1

a hydraulic diagram of the device with a pressure accumulator arrangement; and

2

a perspective view of the accumulator assembly.

In the 1 and 2 a pressure accumulator arrangement 1 with a hydropneumatic pressure accumulator 3 and a further hydropneumatic pressure accumulator 5 is shown. One pressure accumulator 3 is connected on its fluid side 9 to a hydraulic consumer 11 in the form of a piston-cylinder unit 13 to form the device 7, cf. 1 . The further pressure accumulator 5 is connected to a supply source 15, in particular to a hydraulic pump, on its fluid side 17. The two pressure accumulators 3, 5 can be coupled to one another in a gas-conducting manner on their gas sides 19, 21 via a connecting line 23 by means of a regulating device 25. The regulating device 25 comprises a valve 27 switched into the connecting line 23 as a blocking element 29. The further pressure accumulator 5 remains, in compliance with a setpoint pressure specification for the hydraulic consumer 11, in the event of a setpoint pressure deviation exceeding a specifiable value by means of the regulating device 25 to the further pressure accumulator 5 at least for as long connected to the gas line until the target pressure deviation falls below the specified value. Consequently, the locking member 29 is opened when the pressure in a pressure accumulator 3 is higher than the target pressure specification plus the tolerable target pressure deviation and the pressure in the other pressure accumulator 5 is lower than in one Pressure accumulator 3. In this way, one pressure accumulator 3 is relieved by releasing gas. Conversely, the blocking element 29 can be opened when the pressure in one pressure accumulator 3 is lower than the target pressure specification minus the tolerable target pressure deviation and the pressure in the other pressure accumulator 5 is greater than in one pressure accumulator 3. Then one pressure accumulator 3 is filled with gas. The setpoint pressure specification can advantageously consist of a specific pressure value or a pressure range. The actuation of the blocking element 29 of the regulating device 25 can also be timed via a control unit 31 .

One pressure accumulator 3 is designed as a diaphragm accumulator while the other pressure accumulator 5 is a piston accumulator. The piston accumulator 5 has the same or a higher nominal volume and an equal or higher permissible operating pressure than the diaphragm accumulator 3 . A pressure sensor 32 is connected to the connecting line 23 between the gas side 19 of the one pressure accumulator 3 and the blocking element 29 of the regulating device 25 in order to monitor the one pressure accumulator 3 . Furthermore, a connection 35 for filling the gas side 19 of one pressure accumulator 3 is provided in this section 33 of the connecting line 23 . The fluid side 17 of the further pressure accumulator 5 is connected to the supply source 15 via two switching valves 37, 39, which are designed as electromagnetically actuated directional control valves. One valve 37 couples a supply line 41 at one end 43 to either the further pressure accumulator 5 or the hydraulic consumer 11. This valve 37 enables fluid to flow either to the fluid side 17 of the further pressure accumulator 5 or to a piston side 45 of the piston-cylinder unit 13 to forward. The second valve 39 couples the other end 47 of the supply line 41 either to the supply source 15 in the form of a pump 49 or to a tank 51 hydraulic consumer 11 are funded, but also flow in the opposite direction to the tank 51.

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

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 2 the pressure accumulator arrangement 1 is shown in a perspective view. One pressure accumulator 3 is connected to a valve housing block 69 in the form of a membrane accumulator. 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 in order to withstand very high pressures. The connecting line between the two pressure accumulators 3, 5 and the interposed valve 27 of the regulating device 25 are arranged in the valve housing block 69. Furthermore, the valve housing block 69 has a connection 35 for filling up the gas side of 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 one pressure accumulator 3 and the valve 27. The pressure accumulator arrangement 1 is designed to be very space-saving.

Consequently, the accumulator arrangement 1 and the device 7 with the accumulator arrangement 1 show a way in which the capacity of an accumulator 3 can be adjusted during operation by changing the amount of substance on the gas side 19 of an accumulator 3 is. The area of use of the pressure accumulator arrangement 1 is thus increased or the installation of a smaller pressure accumulator 3 is made possible.

Claims (12)

1. Device having a hydraulic consumer (11), a supply source (15), a regulating device (25), a valve (37), a supply line (41) and a pressure accumulator arrangement (1) which comprises one hydropneumatic pressure accumulator (3) and one further hydropneumatic pressure accumulator (5), wherein the one pressure accumulator (3) is connected on its fluid side (9) to the hydraulic consumer (11) and the further pressure accumulator (5) can be connected on its fluid side (17) to the supply source (15), wherein the two pressure accumulators (3, 5) can be linked to each other on their gas sides (19, 21) in a gas-conducting manner by means of the regulating device (25), wherein the one pressure accumulator (3) is adapted to maintain a predefined target pressure for the hydraulic consumer (11), wherein the regulating device (25) is adapted to connect the one pressure accumulator (3) to the further pressure accumulator (5) in a gas-conducting manner in the event of a deviation from the predefined target pressure which exceeds a predefinable value at least until the deviation from the predefined target pressure falls below the predefinable value; wherein the hydraulic consumer (11) is a piston-cylinder unit; wherein the supply line (41) can be linked to the supply source (15); characterised in that the valve (37) is adapted to link one end (43) of the supply line (41) to the hydraulic consumer (11), wherein this valve (37) makes it possible to supply fluid to either the fluid side (17) of the further pressure accumulator (5) or a piston side (45) of the piston-cylinder unit (13).
2. Device according to claim 1, characterised in that the predefined target pressure can be predefined in the form of a pressure value or a pressure range.
3. Device according to claim 1 or 2, characterised in that the predefined target pressure can be predefined as a function of time.
4. Device according to one of the preceding claims, characterised in that the maximum allowable operating pressure of the one pressure accumulator (3) is below the maximum allowable operating pressure of the further pressure accumulator (5).
5. Device according to one of the preceding claims, characterised in that the nominal volume of the one pressure accumulator (3) is below the nominal volume of the further pressure accumulator (5).
6. Device according to one of the preceding claims, characterised in that the one pressure accumulator (3) is a diaphragm accumulator.
7. Device according to one of the preceding claims, characterised in that the further pressure accumulator (5) is a piston accumulator.
8. Device according to one of the preceding claims, characterised in that at least one sensor (32, 55, 61, 63), in particular a pressure sensor or a temperature sensor, is connected 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).
9. Device according to one of the preceding claims, characterised in that the further pressure accumulator (5) can be connected on its fluid side (17) alternately to the supply source (15) or a tank (51) via a further valve (39).
10. Device according to one of the preceding claims, characterised in that a connection is provided (35) for replenishing the gas side (19) of the one pressure accumulator (3).
11. Device according to one of the preceding claims, characterised in that at least one sensor (57, 59, 67), in particular a temperature, pressure or position sensor, is provided on the piston-cylinder unit (13) and in that the sensor (57, 59, 67) is linked to the regulating device (25).
12. Device according to one of the preceding claims, characterised in that the valve is configured as a 3/2-way valve or flow divider valve.

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