Hydraulic drive system and compressor with hydraulic drive system

Abstract

This disclosure relates to a hydraulic drive system (1) particularly for compressing hydrogen, comprising a hydraulic cylinder (2), a fluid supply device (3), and a control device (4), wherein the inner cavity (5) of the cylinder (2) is divided into two chambers (51, 52) by means of a piston (6) of the cylinder (2), and fluid (7) is alternately supplied to the chambers by means of the fluid supply device (3) to cause the piston (6) to move back and forth, wherein the control device (4) is connected to the fluid supply device (3) and configured to control and / or regulate the back and forth movement of the piston (6) by means of a corresponding adjustment command to the fluid supply device (3), wherein the control device (4) is configured to calculate the current position of the piston (6) by means of source data back to the state description of the hydraulic cylinder (2) and / or the fluid supply device (3). This disclosure further relates to a compressor having such a hydraulic drive system (1).

Description

Technical Field

[0001] This invention relates to a hydraulic drive system according to the preamble of claim 1. The invention also relates to a compressor with a hydraulic drive system. Background Technology

[0002] Such a hydraulic drive system is, for example, part of a hydrogen compressor, i.e., a so-called hydrogen compressor. A known hydraulic drive system has a hydraulic cylinder, a fluid supply device, and a control device. The cylinder's interior is divided into two chambers by a piston, and fluid is alternately supplied to these chambers by the fluid supply device to allow the piston to reciprocate. The control device is connected to the fluid supply device and configured to control and / or adjust the piston's reciprocating motion via corresponding adjustment commands to the fluid supply device. Here, the piston position of the preferably bidirectional hydraulic cylinder is detected according to standard procedures using a position sensing device. A measurement of the piston's current position, i.e., a corresponding signal, is continuously maintained to control and / or adjust the piston's position. However, multiple measurements can be obtained at least in two reversing regions of the cylinder, where the piston changes its direction of motion and brakes and accelerates in adjacent directions. These multiple measurements can be generated by multiple sensors and / or by multiple markers at the piston, which can be detected by the at least one sensor. The multiple or continuously existing measurements enable control and / or adjustment of the piston position, particularly the piston's reversal at the desired position within the cylinder. However, this requires significant technical investment and a correspondingly large structural space. Furthermore, when multiple sensors are arranged penetrating the cylinder housing, the sealing of the cylinder's internal cavity must also be considered. Summary of the Invention

[0003] The present invention aims to provide a hydraulic drive system and a compressor incorporating the hydraulic drive system, which reduce or eliminate the problems of the prior art. In particular, the control and / or regulation of the hydraulic drive system should be simplified, and it should also be implemented with particularly low costs in terms of equipment technology.

[0004] This objective is achieved primarily by a hydraulic drive system according to claim 1.

[0005] Other advantageous embodiments are the subject of the dependent claims.

[0006] More precisely, this objective is achieved by a control device configured to calculate the current position of the piston by means of source data traced back to the state description of the hydraulic cylinder and / or fluid supply device.

[0007] In other words, source data that is only indirectly related to the piston's position is used. Based on the system information, i.e., the source data, reflecting the simulated actual position, the piston's current position is calculated. Therefore, the control device is configured to advantageously detect and adjust the piston's position without a direct displacement measurement system, thus simplifying control and / or adjustment overall, and further enabling execution with lower equipment costs. Advantageously, the control device is configured to adjust the piston's position using the calculated current position. Here, an adjustment difference is formed between the target position and the calculated current position. Such adjustment allows for particularly precise control of the piston's current position, or its movement, especially in the optimal compression of efficient fluids such as hydrogen.

[0008] An open or closed system is constructed using hydraulic cylinders and a fluid supply device. Piston movement is generated by the corresponding control of valves and / or pumps. Such valves and / or pumps are part of the fluid supply device. The source data preferably includes measured operating parameters of the valves and / or pumps. Using the source data and known physical dependencies, i.e., the state descriptions, the current position of the piston can then be calculated. Preferably, these physical dependencies, i.e., the state descriptions, are stored in the control device in the form of executable program code.

[0009] In a preferred embodiment of the hydraulic drive system, at least one sensor, particularly a position sensor, is arranged and / or can be arranged at the hydraulic cylinder to detect the determined current position of the piston. The sensor is preferably arranged in a control block. When the piston has a determined relative position with respect to the sensor, particularly passing the sensor, a signal, particularly a signal pulse, can be transmitted to the control device via the position sensor. The precise position of the sensor and / or the associated position of the piston when the signal, particularly the signal pulse, is generated by the sensor is determined during assembly and stored in the control device. The signal, particularly the signal pulse, therefore contains the information that the piston is currently, at the time of signal generation, in the determined and known position. It is also conceivable that the signal is continuously transmitted to the control device, and that the determined changes in the signal are identified by the control device when the piston is positioned or passes through the determined relative position with respect to the sensor.

[0010] Advantageously, the control device is configured to perform initialization, calibration, and / or correction of the calculated current position of the piston by means of a signal generated by the sensor indicating the piston's determined current position. Calibration is performed using the initially determined actual position, obtained via a direct displacement measurement system, particularly by the sensor, based on the simulated actual position reflected in the system information. In a sufficiently accurate state description, a one-time calibration at the start of cylinder operation, i.e., the initialization, is sufficient. The sensor can then be used once and subsequently removed from the cylinder. However, advantageously, calibration and / or correction of the calculated current position of the piston are also performed during operation, reducing the overhead in creating the state description. For example, it is possible to ignore unsealing and / or aging processes of the drive system, such as drive system wear, when creating the state description.

[0011] In an advantageous embodiment of the hydraulic drive system, the position sensor is implemented as a Hall sensor. Such a Hall sensor works in conjunction with the edge of the piston, which is constructed, for example, between the end side of the piston and the outer periphery of the piston, or at the outer periphery of the piston. When the edge subsequently passes the Hall sensor, a signal pulse is generated and forwarded to the control device. Using the signal pulse and known information about the piston's position at the time of its generation, the calculated current position of the piston can then be initialized, calibrated, and / or corrected. As an alternative to the Hall sensor, the use of a magnetostrictive sensor, which can also generate such a signal pulse, is also conceivable.

[0012] In another embodiment of the hydraulic drive system, the sensor is implemented as a pressure sensor. A determined pressure value is then assigned to the determined current position of the piston. The pressure sensor can be advantageously arranged in a region on the end side of the cylinder or in a region on the inner periphery of the cylinder. When the determined pressure value is reached, the assigned position of the piston is then used for initialization, calibration, and / or correction of the calculated current position of the piston.

[0013] More preferably, the piston is capable of moving back and forth between two end positions. The end positions are the two positions of the piston in which the direction of piston movement is reversed. In the end positions, the piston therefore has a velocity of zero during cylinder operation. A so-called reversal zone of the cylinder is constructed near the end positions, in which the piston correspondingly brakes during its operation, i.e., brakes as it moves towards the end positions, and correspondingly accelerates, i.e., accelerates as it moves away from the end positions.

[0014] Preferably, each of the two end positions is equipped with a sensor. The piston, by means of the sensors, can detect at a determined distance relative to the assigned end position within its current determined position. Essentially within this determined distance, the braking process begins as the piston moves towards the assigned end position.

[0015] To facilitate the piston's reversal at its respective end position, i.e., the reversal of its direction of motion, sensors are arranged on each side "in front" of the corresponding end position to detect the current position. The precise positions of the two sensors and / or the piston's corresponding position when the respective sensors generate corresponding signals, especially signal pulses, are determined during assembly and stored in the control unit. This enables repeated referencing, i.e., initialization, calibration, and / or correction of the drive system, as well as precise end-position positioning. Precise end-position positioning means operating the fluid supply device so that the piston, especially in optimal compression of, for example, hydrogen, changes its direction of motion precisely at the desired position.

[0016] Preferably, the current position of the piston can be calculated using the rotational speed of the pump coupled to the hydraulic cylinder via the fluid supply device, the valve position via the valve arrangement of the fluid supply device coupled to the hydraulic cylinder, the temperature of the fluid used to load the hydraulic cylinder, and / or the viscosity of the fluid used to load the hydraulic cylinder. For this purpose, physical parameters are particularly useful, which are necessary to calculate the volumetric flow rate of the fluid reaching and exiting the cylinder cavity sufficiently accurately. Furthermore, given the known dimensions of the hydraulic cylinder, including its piston, the current position of the piston can then be easily calculated using the volumetric flow rate.

[0017] Advantageously, the control device is configured to calculate the piston speed. Specifically, the control device is configured to advantageously adjust the piston speed in the region between the two reversing zones, and thus adjust its position only indirectly. In the two reversing zones, direct position adjustment, i.e., so-called position adjustment, is preferred.

[0018] The objective upon which this invention is based is also achieved by the compressor according to claim 10.

[0019] More precisely, this objective is then achieved by a compressor equipped with the hydraulically driven system described earlier, wherein the compressor is prepared for compressing an effective fluid, particularly hydrogen. Other substances preferably used as gases, such as helium, can also be used as the effective fluid. The effective fluid can be compressed by means of a piston rod protruding from the cylinder housing and fixedly connected to the piston. This piston rod moves with the piston as the piston moves. By means of a hydraulic cylinder, a high force density can be achieved through its piston rod during operation, enabling particularly high and efficient compression of the effective fluid.

[0020] In summary, the described hydraulic drive system and compressor are suitable for a wide variety of applications, such as the compression of hydrogen for gas stations, (pressure) storage facilities, and / or pipelines. Attached Figure Description

[0021] The preferred embodiments are shown in more detail below with reference to the accompanying drawings.

[0022] Figure 1 The hydraulic circuit diagram of the hydraulic drive system is shown schematically. Detailed Implementation

[0023] Especially for compressed hydrogen Figure 1 The hydraulic drive system 1 mainly comprises a hydraulic cylinder 2, a fluid supply device 3, and a control device 4. The inner cavity 5 of the cylinder 2 is divided into two chambers 51 and 52 by means of a preferably bidirectional piston 6. Fluid 7 is alternately supplied to these chambers by the fluid supply device 3 to allow the piston 6 to reciprocate. The control device 4 is connected to the fluid supply device 3 and configured to control and / or adjust the reciprocating motion of the piston 6 via corresponding adjustment commands directed to the fluid supply device 3. The connection between the control device 4 and the fluid supply device 3 for transmitting adjustment commands and / or data is indicated here by a dashed line. This could be a cable arranged between the control device 4 and the fluid supply device 3. However, wireless transmission of adjustment commands and / or data is also conceivable.

[0024] The control device 4 is configured to calculate the current position of the piston 6 using source data traced back to the state description of the hydraulic cylinder 2 and / or the fluid supply device 3. For this purpose, the control device 4 has, for example, a computer and / or a microcontroller, by which corresponding software can be implemented, and by which the aforementioned calculations can be performed. Specifically, the source data is transmitted to the control device 4 via the aforementioned connection between the control device 4 and the fluid supply device 3. The source data then resides in the aforementioned software used to calculate the current position of the piston 6. The control device 4 is further configured to adjust the position of the piston 6 using the calculated current position. During adjustment, the adjustment difference between the target position and the calculated current position is calculated. From the adjustment difference, adjustment parameters, i.e., adjustment commands, for the fluid supply device 3 are obtained by means of a regulator, preferably implemented using the software implemented by the control device 4.

[0025] At least one sensor 8, particularly a position sensor 8, is arranged and / or can be arranged at the hydraulic cylinder 2 to detect the determined current position of the piston 6. The sensor 8 is arranged, for example, centrally located and / or can be arranged at the cylinder 2. Here, the connection between the sensor 8 and the control device 4 for transmitting data, particularly the signals generated by the sensor, is indicated by a dotted line.

[0026] Control device 4 is configured to perform initialization, calibration, and / or correction of the calculated current position of piston 6 by means of a signal generated by sensor 8 of the determined current position of piston 6. The current position of piston 6 is calculated during piston 6 operation, for example, based on the known, initially measured position of piston 6 and the stroke traversed by piston 6 from the measurement time point. This initial measurement of the current position of piston 6 is also referred to as initialization. After initialization, calibration can be performed upon re-detection of the signal generated by sensor 8, in which the difference between the calculated current position of piston 6 and the current position detected by sensor 8 is determined. For example, the calculation of the current position of piston 6 can be optimized based on this difference, i.e., particularly improving the status description of hydraulic cylinder 2 and / or fluid supply device 3. Furthermore, the calculated current position of piston 6 is corrected by means of the current position determined primarily by sensor 8, specifically by replacing the calculated current position of piston 6 with the current position determined primarily by sensor 8 for that determined time point; this can also be referred to as reinitialization.

[0027] The position sensor 8 is implemented, for example, as a Hall sensor. Such a Hall sensor has a current-carrying semiconductor element continuously magnetically preloaded by a magnetic field from a permanent magnet fixed behind it. When a piston made of and / or at least partially of such a ferromagnetic material is now immersed in this magnetic field, its field strength is affected, thereby determining a change in voltage within the semiconductor element. This voltage then manifests as a signal from the sensor 8. The aforementioned signal pulse corresponds in particular to the determined change in the signal, particularly the voltage. The sensor 8, particularly the position sensor 8, particularly the Hall sensor, is arranged, for example, on the side of the housing 11 forming the cavity 5 of the cylinder 2 away from the cavity 5. It is also conceivable that the sensor 8 penetrates such a housing 11 and / or is arranged within the cavity 5, such that at least one measuring area of ​​the sensor 8 is arranged within the cavity 5 and, in particular, has contact with the fluid 7.

[0028] Sensor 8 can also be implemented as a pressure sensor, wherein the determined current position of piston 6 is assigned a determined pressure value. This assignment can be performed by means of sensor 8 itself and / or by means of control device 4.

[0029] Piston 6 is capable of moving back and forth between two terminal positions 91 and 92. Piston 6 is shown with dashed lines at the two terminal positions 91 and 92. As piston 6 moves toward its assigned terminal position 91 or 92, a braking process occurs until the piston has a velocity of zero at terminal position 91 or 92. From that terminal position 91 or 92, piston 6 accelerates toward the other terminal position 92 or 91. Preferably, piston 6 moves at a substantially constant speed between the acceleration process after reaching one of terminal positions 91 or 92 and the braking process for reaching the other terminal position 92 or 91.

[0030] Each of the two terminal positions 91 and 92 is optionally equipped with a sensor 8 (in Figure 1 (The connections for data transmission are shown in dashed lines). When using the two sensors 8 assigned to the two terminal positions 91 and 92, it is preferable to omit the sensor 8 located in the middle of cylinder 2. The piston 6 can then detect, with the aid of the two sensors 8 shown in dashed lines, at a determined distance relative to the assigned terminal positions 91 and 92 at the determined current position, wherein the braking process begins substantially within this determined distance as the piston 6 moves toward the assigned terminal positions 91 and 92.

[0031] The current position of piston 6 can be calculated by means of the rotational speed of pump 10 coupled to hydraulic cylinder 2 of fluid supply device 3, the valve position of valve arrangement structure coupled to hydraulic cylinder 2 of fluid supply device 3, the temperature of fluid 7 used to load hydraulic cylinder 2, and / or the viscosity of fluid 7 used to load hydraulic cylinder 2. Figure 1 The fluid supply device 3 is constructed by means of a pump 10 and wiring arranged between the connectors and chambers 51, 52 of the pump 10. Instead of the pump 10, different types of pressure sources can also be used, such as corresponding pressure reservoirs. It is also conceivable that valves in a valve arrangement structure are arranged between such pressure sources, especially the pump 10 and / or pressure reservoir, and cylinder 2, especially its chambers 51, 52. As the pump 10, for example, an axial piston pump, a radial piston pump, and / or a vane pump, respectively preferably having a settable discharge volume, can be provided.

[0032] The control device 4 is configured to calculate the speed of the piston 6. The speed of the piston 6 can then be adjusted, at least in sections, especially by means of the control device 4.

[0033] The hydraulic drive system 1 is part of the compressor (not shown here), which is designed to compress a viable fluid, particularly hydrogen. During compressor operation, the viable fluid is compressed using a piston rod 12 that protrudes from the housing 11 of cylinder 2 and is fixedly connected to piston 6. The compressed viable fluid can be stored, in particular, in a corresponding pressure reservoir and / or in a system consisting of two or more pressure reservoirs.

[0034] List of reference numerals in the attached diagram: 1. Hydraulic drive system 2 Hydraulic cylinders 3. Fluid supply device 4. Control device The inner cavity of cylinder 2 of cylinder 5 51 The first chamber of the inner cavity 5 52 The second chamber of inner cavity 5 6-cylinder 2-piston 7. Fluid 8. Sensors, especially position sensors 91 First Terminal Location 92 Second Terminal Location 10 pumps 11. Shell 12 Piston Rod

Claims

1. A hydraulic drive system (1) particularly for compressing hydrogen, comprising a hydraulic cylinder (2), a fluid supply device (3), and a control device (4), wherein, The inner cavity (5) of the cylinder (2) is divided into two chambers (51, 52) by means of the piston (6) of the cylinder (2). In order for the piston (6) to move back and forth, fluid (7) can be alternately supplied to the chambers by means of the fluid supply device (3). The control device (4) is connected to the fluid supply device (3) and is configured to control and / or adjust the back and forth movement of the piston (6) by means of the corresponding adjustment command at the fluid supply device (3). The control device (4) is characterized in that it is configured to calculate the current position of the piston (6) by means of source data back to the state description of the hydraulic cylinder (2) and / or the fluid supply device (3).

2. The hydraulic drive system (1) according to claim 1, characterized in that, At least one sensor (8), particularly a position sensor (8), is arranged and / or can be arranged at the hydraulic cylinder (2) to detect the determined current position of the piston (6).

3. The hydraulic drive system (1) according to claim 2, characterized in that, The control device (4) is configured to perform initialization, calibration and / or correction of the calculated current position of the piston (6) by means of a signal generated by the sensor (8) of the determined current position of the piston (6).

4. The hydraulic drive system (1) according to any one of claims 2 or 3, characterized in that, The position sensor (8) is implemented as a Hall sensor.

5. The hydraulic drive system (1) according to any one of claims 2 to 4, characterized in that, The sensor (8) is implemented as a pressure sensor, wherein the piston (6) is assigned a determined pressure value at its determined current position.

6. The hydraulic drive system (1) according to any one of the preceding claims, characterized in that, The piston (6) is capable of moving back and forth between two end positions (91, 92).

7. The hydraulic drive system (1) according to claim 6, characterized in that, Each of the two terminal positions (91, 92) is equipped with a sensor (8), wherein the piston (6) is able to detect at a determined current position at a determined distance relative to the assigned terminal position (91, 92) by means of the sensor (8), wherein the braking process begins substantially within the determined distance as the piston (6) moves toward the assigned terminal position (91, 92).

8. The hydraulic drive system (1) according to any one of the preceding claims, characterized in that, The current position of the piston (6) can be calculated by means of the rotational speed of the pump (10) coupled to the hydraulic cylinder (2) of the fluid supply device (3), the valve position of the valve arrangement structure coupled to the hydraulic cylinder (2) of the fluid supply device (3), the temperature of the fluid (7) used to load the hydraulic cylinder (2), and / or the viscosity of the fluid (7) used to load the hydraulic cylinder (2).

9. The hydraulic drive system (1) according to any one of the preceding claims, characterized in that, The control device (4) is configured to calculate the speed of the piston (6).

10. A compressor having a hydraulic drive system (1) according to any one of the preceding claims, wherein, The compressor is intended for use in compressing effective fluids, particularly hydrogen.

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