Diaphragm pump and device and method for delivering a fluid and related control unit

Abstract

It is proposed in a device (1) and a method for conveying a fluid (2) to use a positive displacement pump (3), in particular a diaphragm pump (16), with an adjustable stroke amplitude (h), and the stroke amplitude (h) of the positive displacement pump (3) is controllable by a control unit (6). The stroke frequency (f) of the positive displacement pump (3) can be controlled such that it lies outside the hydraulic 10 resonance frequency of the device (1). The stroke amplitude (h) of the positive displacement pump (3) can be controlled depending on a measured flow parameter (see Fig. 1).

Description

[0001] This invention relates to diaphragm pumps, which include a stroke element having an adjustable stroke amplitude. Such diaphragm pumps are known in practice.

[0002] The present invention also relates to an apparatus for conveying fluids. The apparatus includes a positive displacement pump. The apparatus also includes a hydraulic energy storage element and piping. The present invention further relates to a method for conveying fluids by means of such an apparatus. Such apparatus and methods are known in practice.

[0003] Positive displacement pumps are preferably diaphragm pumps. Positive displacement pumps are preferably constructed for conveying liquids, such as water in particular.

[0004] The present invention also relates to a method for determining the hydraulic resonant frequency of a device for conveying fluid.

[0005] The present invention also relates to a control unit, which can be used to control a device for conveying fluid.

[0006] The periodic suction and pressure phases cause pressure and volumetric flow rate pulsations in positive displacement pumps. These pulsations can be reduced using hydraulic energy storage elements. The applicant has discovered that these pulsations are frequency-dependent. The applicant has found that in many applications, energy storage elements and piping cause hydraulic resonant frequencies at which pressure and volumetric flow rate pulsations reach their maximum values. In practice, positive displacement pumps are typically controlled by a rotary motor and an eccentric drive with a constant stroke. To adjust the delivery rate, the speed is typically adjusted, thereby adjusting the pump frequency, which results in high pulsations when the frequency changes, passing through the resonant frequency.

[0007] The object of this invention is to improve fluid transport. In particular, stable fluid transport and reduced energy consumption should be achieved. Preferably, this object should be achieved by reducing pressure pulsation and volumetric flow rate pulsation.

[0008] To achieve this objective, the present invention provides the features of claim 1. In particular, according to the present invention, a diaphragm pump of the type described in the introduction is proposed, the diaphragm pump having a backlash-free linear drive mechanism configured as a direct drive mechanism for driving the stroke element.

[0009] A backlash-free drive mechanism is characterized by the backlash-free stroke motion of the stroke element. Specifically, for this purpose, in a direct drive mechanism, the stroke element is fixedly fastened to the diaphragm of the diaphragm pump.

[0010] Backlash-free operation is particularly advantageous for small stroke amplitudes and high frequencies. The backlash present in the drive mechanism limits the minimum stroke the pump can operate on. This is not a problem for the current applications of diaphragm pumps. However, the inventors have recognized that a backlash-free, direct linear drive mechanism can significantly expand the application possibilities of pulsating damping pumps, as the pump can then operate at high frequencies and small stroke amplitudes. Furthermore, this allows for a very wide range of delivery rates while maintaining precise operating modes. In particular, resonant frequencies can be avoided.

[0011] Linear drive mechanisms can only perform translational motion, not rotational motion. Therefore, the stroke amplitude of the stroke element can be controlled with particularly precise and variable accuracy using linear drive mechanisms.

[0012] Direct-drive mechanisms offer the following advantages: there is no transmission device in the drive mechanism, therefore there is no backlash in the stroke movement of the stroke element. This allows for rapid and precise control of the stroke element. Furthermore, the use of a direct-drive mechanism enables a longer service life for the diaphragm pump because the transmission components do not experience wear.

[0013] In addition, the diaphragm pump has a hydraulic energy storage element and a control unit, which can be used to control the stroke amplitude of the stroke element.

[0014] A hydraulic energy storage element can have two chambers separated from each other by a partition layer (e.g., an elastomer plate or diaphragm). One chamber can be in contact with the fluid to be transported. The other chamber can be at atmospheric pressure or other pressures. Furthermore, the other chamber can have a spring element supporting the partition layer. Such a hydraulic energy storage element can compensate for any pressure and volumetric flow pulsations generated by a diaphragm pump, resulting in more uniform flow conditions in the pipeline. Therefore, the energy storage element can also be called a pulsation damper.

[0015] The diaphragm pump preferably has a pipeline connected to the diaphragm pump. The hydraulic energy storage element is particularly preferably arranged in the pipeline.

[0016] By controlling the stroke amplitude, the desired flow rate and / or pressure can be adjusted by changing the stroke amplitude. Therefore, the diaphragm pump can operate continuously at high stroke frequencies, preferably greater than 20Hz, 30Hz, 50Hz, 100Hz, 200Hz, or even greater than 500Hz, or at stroke frequencies in the range between the aforementioned frequencies and at least 500Hz, for example, at a stroke frequency in the range between at least 50Hz and 500Hz. This allows for a compact and space-saving structure for the diaphragm pump. Furthermore, operating at high stroke frequencies minimizes pressure pulsation and / or volumetric flow rate pulsation.

[0017] Sensors, such as pressure sensors and / or volumetric flow sensors, can be connected to the control unit so that the stroke amplitude can be controlled based on the measured values.

[0018] Here, flow parameters, such as pressure or volumetric flow rate, can be adjusted in the control unit. The stroke amplitude can be adjusted according to the flow parameters. In particular, the diaphragm pump has an interface for connecting to the control unit, through which flow parameters, or parameters that can be converted into flow parameters, can be read as input values. Flow parameters can also be input through a user interface.

[0019] In a favorable design, the linear drive mechanism can be configured as an electromagnetic drive mechanism. This allows for precise control of the linear drive mechanism.

[0020] The linear drive mechanism is preferably configured as an electric drive mechanism. The structure of the electric drive mechanism includes a rigid coil armature and a moving rotor with a permanent magnet, or conversely, the device includes a rigid permanent magnet armature and a moving rotor with a coil. When current flows through the coil, and the current flows perpendicular to the magnetic field, a force (Lorentz force) perpendicular to both the current and the magnetic field is generated. This force causes the coil to move in the case of a fixed permanent magnet armature, or causes the permanent magnet armature to move in the case of a fixed coil. If the current direction is reversed, the direction of the force is also reversed. The electric drive mechanism is preferably stepless on the coil side. Preferably, the aforementioned coil is energized with an alternating winding direction corresponding to the alternating magnetic field direction. Then, the Lorentz force can act directly between the magnetic field of the permanent magnet and the coil.

[0021] Because the force generated by an electric drive mechanism is proportional to and very direct with the applied current—that is, without time deviation—it can be used to control diaphragm pumps very precisely and with a fast response. Furthermore, the electric drive mechanism enables diaphragm pumps to operate at high stroke frequencies.

[0022] In another advantageous design, the hydraulic energy storage element can be specified to be arranged on the suction side or the pressure side of the pump chamber of the diaphragm pump.

[0023] In another advantageous design, the diaphragm pump can be specified to have a pump housing that surrounds the hydraulic energy storage element and the stroke element. The pump housing may also surround other or all components of the diaphragm pump, such as the drive mechanism, diaphragm, valves, valve chambers, and / or pump chambers. In particular, the pump housing may completely surround the diaphragm pump. This shared pump housing allows for a particularly compact structure, thereby preventing functional damage to the hydraulic energy storage element due to piping.

[0024] In another advantageous design, the passage can be configured between the cavity of the hydraulic energy storage element and the valve chamber of the diaphragm pump. The passage preferably leads directly and / or without connections into the cavity. This design can be implemented in one, more, or all hydraulic energy storage elements. This can optionally be combined with a common pump housing to achieve a particularly compact structure and with minimal piping-related impacts because the passage can be designed to be very short.

[0025] Alternatively, the hydraulic energy storage element of the diaphragm pump can also be arranged outside the pump housing and connected to the pump chamber via a pipeline section.

[0026] In another advantageous design, the hydraulic energy storage element can be arranged on the suction side, and the diaphragm pump has another hydraulic energy storage element arranged on the pressure side. This allows for compensation of pressure pulsations and volumetric flow rate pulsations both on the suction and pressure sides of the diaphragm pump. Here, the other hydraulic energy storage element can be constructed as the first hydraulic energy storage element.

[0027] In another advantageous design, the diaphragm pump may be specified to have two pump chambers, each defined by a diaphragm, wherein the two diaphragms are connected to each other via a stroke element.

[0028] This design eliminates the need for additional support elements for the stroke components, as the stroke components are adequately supported by two diaphragms.

[0029] In a linear drive mechanism, the dual-head nature of the diaphragm pump described herein provides greater robustness against drift and stably maintains the rotor's intermediate position. Thus, displacement of the rotor's intermediate position during one half-stroke can be compensated for by the subsequent half-stroke. This reduces the requirement for active rotor position control. The need for rotor intermediate position correction can be eliminated. Furthermore, position sensors for determining rotor position are not required.

[0030] Because the two diaphragms are connected to each other via stroke elements, the two pump chambers can operate alternately. Through the stroke motion of the stroke elements, fluid is drawn into one pump chamber while simultaneously being discharged from the other. Thus, the two pump chambers can operate without interfering with each other. With this design, the pump chambers are always in different phases: when the first pump chamber is in the suction phase (i.e., the intake process), the second pump chamber is in the pressure phase (i.e., the discharge process), and vice versa. This stabilizes the flow conditions on both the suction and pressure sides of the diaphragm pump.

[0031] The diaphragm pump preferably has a hydraulic energy storage element on the suction side and another on the pressure side, with each hydraulic energy storage element connected to one of the two pump chambers. Therefore, on the suction side, a single hydraulic energy storage element shared by both pump chambers is connected to both chambers. Similarly, on the pressure side, a single hydraulic energy storage element shared by both pump chambers is connected to both chambers. This eliminates the need for separate hydraulic energy storage elements for each of the two pump chambers, thereby reducing the installation space required for the diaphragm pump.

[0032] Therefore, the described dual-head diaphragm pump can have one, two, three, four or more hydraulic energy storage elements.

[0033] In another advantageous design, the diaphragm pump can be specified to have at least four hydraulic energy storage elements, with two hydraulic energy storage elements arranged on the suction side of the pump chamber and two hydraulic energy storage elements arranged on the pressure side of the pump chamber. Thus, one hydraulic energy storage element is arranged on both the suction and pressure sides of each pump chamber. This better reduces pressure pulsation and volumetric flow rate pulsation.

[0034] To achieve the aforementioned objective, it can be specified that the previously described diaphragm pump and its variants are used in an apparatus comprising the diaphragm pump and piping connected to the diaphragm pump.

[0035] Alternatively or additionally, to achieve the aforementioned objective, according to the invention, features of a first parallel independent claim relating to an apparatus for conveying fluid are provided. In particular, according to the invention, in apparatuses of the type described above, it is proposed that the stroke amplitude of the positive displacement pump is adjustable. The positive displacement pump is preferably configured as a diaphragm pump. The positive displacement pump can particularly be configured as described above or below; in this case, the hydraulic energy storage element of the apparatus and the hydraulic energy storage element of the diaphragm pump are preferably integrated, i.e., they are the same component. The apparatus also includes a control unit connected to the positive displacement pump. It is also specified that the stroke amplitude of the positive displacement pump can be controlled by the control unit, and the control unit is configured such that the stroke frequency of the positive displacement pump is outside the hydraulic resonant frequency of the apparatus.

[0036] Here, the piping can connect the positive displacement pump to the fluid reservoir on the suction side. The piping can also connect the positive displacement pump to the same fluid reservoir, another fluid reservoir, or a fluid consumer on the pressure side. Therefore, fluid can be transported from the first fluid reservoir to the second fluid reservoir via the piping through the positive displacement pump, wherein, instead of the second fluid reservoir, the piping can also return to the first fluid reservoir.

[0037] One or more hydraulic energy storage elements can be arranged in the pipeline. The hydraulic energy storage elements are preferably placed on the suction side of the positive displacement pump. Furthermore, the hydraulic energy storage elements are preferably placed on the pressure side of the positive displacement pump.

[0038] The hydraulic resonant frequency corresponds to the frequency at which pressure pulsations and / or volumetric flow rate pulsations in the pumped fluid are greatest. The hydraulic resonant frequency can be determined empirically or calculated. The hydraulic resonant frequency approximately corresponds to the stroke frequency of a positive displacement pump, at which pressure pulsations and / or volumetric flow rate pulsations in the pumped fluid are greatest.

[0039] It has been shown that in the device, pressure pulsation can begin from a resting state and initially increase with increasing frequency, reaching its maximum at the hydraulic resonant frequency. If the frequency increases further, the pressure pulsation will decrease again until it reaches a constant value, within which the pressure pulsation no longer depends on the frequency.

[0040] Volumetric flow rate pulsation can also increase with increasing frequency, reaching its maximum at the hydraulic resonant frequency. As the stroke frequency continues to increase, the volumetric flow rate pulsation will decrease again.

[0041] Therefore, it may be advantageous to avoid hydraulic resonance frequencies when selecting stroke frequencies, as this enables constant fluid delivery while reducing fluid pressure pulsations and / or flow rate pulsations.

[0042] The adjustability and controllability of the stroke amplitude of a positive displacement pump offer the following advantages: even when adjusting the stroke frequency would trigger the maximum hydraulic resonance value, the fluid delivery rate and / or pressure can be flexibly adjusted. Therefore, any target value for fluid pressure and / or flow rate can be achieved without the risk of the stroke frequency falling within the range of hydraulic resonance frequencies.

[0043] The stroke frequency being outside the hydraulic resonant frequency preferably means that the stroke frequency is below 90% or above 110% of the resonant frequency. Particularly preferably, the lower limit is 80% of the resonant frequency and the upper limit is 125% of the resonant frequency. More preferably, the lower limit is 70% of the resonant frequency and the upper limit is 140% of the resonant frequency.

[0044] In a favorable design, the control unit can be configured in operating mode to maintain a constant stroke frequency. This avoids frequency-dependent pressure and / or volumetric flow rate pulsations and ensures stable fluid delivery.

[0045] It can be specified here that the stroke frequency, while variable, remains constant. Alternatively, it can be specified that the control unit is configured such that the stroke frequency is immutable. In this way, it can be ensured that the stroke frequency has an optimal value at which pressure pulsations and / or volumetric flow rate pulsations are minimized.

[0046] Alternatively or additionally, the control unit may be configured such that the stroke frequency is higher than the hydraulic resonant frequency. Here, "higher than" means preferably higher than 110% of the resonant frequency, particularly preferably higher than 120% of the resonant frequency, and very particularly preferably higher than 140% of the resonant frequency. If the stroke frequency is higher than the resonant frequency, a high delivery rate can be achieved with low pulsation.

[0047] In another advantageous design, it can be specified that the control unit is configured to operate at a minimum stroke frequency in one operating mode, and particularly in another operating mode.

[0048] Here, the minimum value can be a value higher than the hydraulic resonant frequency. This value can preferably be 110%, 120%, or 140% of the hydraulic resonant frequency. This ensures that the stroke frequency is outside the hydraulic resonant frequency and that pressure pulsation and volumetric flow pulsation are particularly small.

[0049] The control unit is preferably configured such that when the fluid delivery rate decreases, the stroke amplitude decreases first, and the stroke frequency decreases only when the minimum stroke amplitude is reached.

[0050] In this way, the conveying rate can be changed by controlling the stroke frequency and the stroke amplitude. This is advantageous, for example, when the required conveying rate is too low to be achieved by simply controlling the stroke amplitude at a high stroke frequency. Simultaneously, by pre-setting a minimum value, the stroke frequency is ensured to be higher than the hydraulic resonant frequency.

[0051] Alternatively or additionally, to achieve the aforementioned objective, according to the invention, a second parallel independent claim is provided, relating to an apparatus for conveying fluid. In particular, to achieve the aforementioned objective, according to the invention, in apparatuses of the type described above, it is proposed that the stroke amplitude of the positive displacement pump is adjustable. The positive displacement pump is preferably configured as a diaphragm pump. The positive displacement pump can particularly be configured as described above or below; in this case, the hydraulic energy storage element of the apparatus and the hydraulic energy storage element of the diaphragm pump are preferably integrated, i.e., they are the same component. The apparatus also includes a control unit connected to the positive displacement pump. The apparatus also includes sensors for measuring the flow parameters of the fluid. Furthermore, it is specified that the stroke amplitude of the positive displacement pump can be controlled by the control unit based on the flow parameters measured by the sensors.

[0052] In this way, for example, the measured flow parameters can be adjusted to a pre-defined target value. The controllability of the stroke amplitude offers the advantages that the stroke frequency does not need to be controlled, and the stroke frequency can be kept substantially constant and / or outside the resonant frequency of the device, preferably at a higher value. Therefore, pressure pulsations and / or volumetric flow rate pulsations of the fluid can be minimized.

[0053] In a favorable design, the flow parameters can be specified as pressure and / or flow rate. Therefore, the pressure and / or flow rate at the sensor location can be adjusted by controlling the stroke amplitude of the positive displacement pump.

[0054] In another advantageous design, the sensor may be configured and arranged such that the offset of the separator layer of the hydraulic energy storage element can be measured by the sensor, and the pressure, such as the aforementioned pressure, can be determined by the control unit based on the measured offset.

[0055] This offers the following advantages: the pressure sensor can be directly mounted in the hydraulic energy storage element. This is particularly space-saving because it eliminates the need to install the pressure sensor in the pipeline, and because the pulsation in the energy storage element is minimal, accurate pressure measurement is achieved.

[0056] In another advantageous design, the stroke frequency of the positive displacement pump, such as the aforementioned stroke frequency, can be specified to be controlled by a control unit based on flow parameters measured by a sensor.

[0057] Therefore, positive displacement pumps can be controlled not only by stroke amplitude but also by stroke frequency. The advantage here is greater control flexibility. In particular, it is possible to achieve exceptionally high and exceptionally low flow parameters, which is impossible to achieve by controlling stroke amplitude alone.

[0058] In another advantageous design, the piping can be configured with orifices to increase flow resistance. Here, the orifice supports the damping effect of the hydraulic energy storage element, reducing pressure and volumetric flow pulsations generated by the positive displacement pump. Furthermore, the orifice can effectively influence the resonant characteristics of the hydraulic system. Moreover, by installing an orifice, the resonant frequency of the hydraulic system can be lowered, thus providing a wider stroke frequency range above the resonant frequency for the positive displacement pump's operation.

[0059] Here, the orifice can be arranged on the suction side of the positive displacement pump. The orifice is preferably arranged such that the hydraulic energy storage element is located between the positive displacement pump and the orifice. This reduces pressure pulsations and volumetric flow rate pulsations on the suction side of the positive displacement pump.

[0060] Alternatively or additionally, an orifice can be arranged on the pressure side of the positive displacement pump. The orifice is preferably arranged such that the hydraulic accumulator element is located between the positive displacement pump and the orifice. This has the advantage that the fluid delivered by the positive displacement pump flows first into the hydraulic accumulator element because the flow resistance to the fluid flowing into the hydraulic accumulator element is lower than the flow resistance generated when the fluid flows directly into the pipeline through the orifice. In this way, pressure pulsations and volumetric flow rate pulsations on the pressure side of the positive displacement pump can be reduced.

[0061] In another advantageous design, the hydraulic energy storage element can be arranged on the suction side of the positive displacement pump, and the device can have another hydraulic energy storage element arranged on the pressure side of the positive displacement pump. Therefore, pressure pulsation and volumetric flow rate pulsation can be reduced on both the pressure and suction sides.

[0062] In another advantageous design, the stroke amplitude can be specified to be controlled within a range of 10 times, preferably at least 20 times, 50 times, or 100 times. This provides particularly high flexibility in controlling the device, especially when adjusting specific pressures and / or specific flow rates.

[0063] In another advantageous embodiment, the control unit may be configured such that the stroke frequency (e.g., the aforementioned stroke frequency) is between 0.7 and 1.4 times the mechanical resonant frequency of the positive displacement pump, preferably between 0.8 and 1.2 times, and particularly preferably between 0.9 and 1.1 times. For example, the stroke frequency may correspond to the mechanical resonant frequency of the positive displacement pump.

[0064] The stroke element of a positive displacement pump can be supported, for example, by means of a leaf spring, or in the case of a diaphragm pump, by means of a pump diaphragm. Therefore, the mechanical resonant frequency of the corresponding pump is the resonant frequency of the system, which specifically consists of an oscillating stroke element and elements supporting that stroke element (e.g., a pump diaphragm and / or a leaf spring).

[0065] Adjusting the stroke frequency to be close to the mechanical resonant frequency is particularly advantageous in terms of energy, because it allows the positive displacement pump to operate under mechanical resonance. In this way, the largest portion of the electrical energy used to drive the stroke elements can be converted into fluid transport. This results in a reduction in the energy consumption of the positive displacement pump.

[0066] Here, the stroke frequency is preferably kept constant. Therefore, the energy consumption of the corresponding pump can be kept at a constant low level.

[0067] In another advantageous design, the positive displacement pump can be specified to have a linear drive mechanism. This means that the positive displacement pump does not have a rotary drive mechanism and can only perform translational motion by driving the diaphragm pump. By avoiding rotating parts in the drive mechanism, a faster response to adjustment signals from the control unit can be achieved. Linear drive mechanisms are particularly suitable for applications requiring adjustable and controllable stroke amplitude.

[0068] Preferably, the linear drive mechanism is an electromagnetic drive mechanism. An electromagnetic drive mechanism means that the stroke element of the positive displacement pump moves via electromagnetic induction rather than via a transmission device. This allows for simpler adjustment of the stroke amplitude and stroke frequency.

[0069] Alternatively or additionally, the drive mechanism of a positive displacement pump, particularly a linear drive mechanism, is a direct drive mechanism. By using a direct drive mechanism, there is no transmission device in the drive mechanism, and therefore no backlash during the stroke, allowing the drive mechanism to respond more quickly to adjustment signals from the control unit. Furthermore, this minimizes the need for maintenance, and because there is no wear on transmission components, a longer service life can be achieved for the positive displacement pump.

[0070] In another advantageous design, it can be specified that the stroke position of the positive displacement pump can be detected by a position sensor, and the position sensor is connected to the control unit.

[0071] The stroke position corresponds to the current position of the stroke element. A position sensor can be used to detect the value of the current stroke amplitude. With the help of a position sensor, it can be verified, for example, whether the target value of the stroke amplitude preset by the control unit has actually been executed.

[0072] In another advantageous design, the positive displacement pump can be specified to operate with a clearance volume (Kopfspiel) capable of conveying both liquids and gaseous media, and the stroke amplitude can be adjusted according to the clearance volume via a control unit. Alternatively or additionally, the zero position (Nulllage) of the stroke element can be adjusted according to the clearance volume using the control unit. When conveying gaseous media, it is particularly advantageous to keep the clearance volume as small as possible and thus maintain the compression ratio as large as possible. This can be achieved by maximizing the stroke amplitude and / or shifting the zero position (Neutrallage) of the stroke element, and thus the neutral position (i.e., zero line) of the stroke movement, in the pump head direction.

[0073] In an advantageous design, the control unit may be configured to control the device to perform the method described below.

[0074] Using the above-described apparatus, a method for conveying fluid can be performed, wherein the stroke amplitude and / or stroke frequency of the positive displacement pump are controlled.

[0075] To achieve the aforementioned objective, according to the invention, features are provided in a first parallel independent claim relating to a method for conveying fluid. Specifically, to achieve the aforementioned objective, according to the invention, in methods of the type described above, it is proposed that the stroke amplitude of the positive displacement pump is adjustable. Furthermore, it is specified that the stroke amplitude of the positive displacement pump is controlled, and the stroke frequency of the positive displacement pump is kept outside the hydraulic resonant frequency of the device.

[0076] By keeping the stroke frequency outside the hydraulic resonant frequency, pressure and volumetric flow pulsations can be reduced, allowing fluid to be delivered under stable flow conditions. Fluid flow conditions can be flexibly adjusted by controlling the stroke amplitude. Since unnecessary energy is not required to generate pressure and volumetric flow pulsations, the energy consumption of positive displacement pumps can also be reduced.

[0077] The meaning of "outside the resonant frequency" has been described above in conjunction with the apparatus. Since this method can be specifically performed using the aforementioned apparatus, the definition and modifications of the apparatus also apply accordingly to the method.

[0078] Alternatively or additionally, to achieve the aforementioned objective, according to the invention, a second parallel independent claim is provided, relating to a method for conveying fluid. In particular, to achieve the aforementioned objective, according to the invention, in methods of the type described above, it is proposed that the stroke amplitude of the positive displacement pump is adjustable. Furthermore, it is specified that flow parameters of the fluid are measured and the stroke amplitude of the positive displacement pump is controlled based on the measured flow parameters.

[0079] Advantageously, there is no need to change the stroke frequency to adjust the flow parameters, as this can be done by controlling the stroke amplitude. Thus, the stroke frequency can be maintained at a high value, which can also be higher than the hydraulic resonant frequency, minimizing pressure pulsation and volumetric flow pulsation.

[0080] In an advantageous implementation, the stroke frequency of the positive displacement pump can be specified to be controlled based on the measured flow parameters, such as the aforementioned stroke frequency. This provides another degree of freedom, in addition to controlling the stroke amplitude, to adjust the flow parameters.

[0081] In another advantageous implementation, it can be specified that the stroke amplitude is adjusted to its maximum value until the positive displacement pump is filled with liquid, and then the stroke amplitude is subject to variable control.

[0082] This is particularly advantageous during the startup or initialization of the delivery process of a positive displacement pump. During startup, there is typically no liquid in the lines or the positive displacement pump; it is filled with air or other gases. Therefore, the positive displacement pump must first draw in liquid. For this purpose, the positive displacement pump must deliver gas. For gas delivery, it is advantageous to have the maximum stroke. This results in a smaller dead volume in the pump chamber and a higher compression ratio. Thus, a larger volume of gas can be delivered. Furthermore, only in this way can a sufficiently large vacuum be created to draw liquid into the pump through the suction side line. Once the liquid is drawn in, reaches the positive displacement pump, and fills the pump chamber, the stroke can be reduced again and controlled, allowing for, for example, adjustment of the desired flow parameters.

[0083] In another advantageous embodiment, a target value for the flow parameter can be predetermined, and this target value can be compared with a measured value of the flow parameter. The stroke amplitude can then be controlled based on the comparison result. Preferably, this ensures that the measured value matches the target value.

[0084] Therefore, the flow conditions of the fluid can be adjusted to meet the corresponding requirements.

[0085] In another advantageous embodiment, the adjustment variable for the stroke amplitude can be specified to be updated in time steps, wherein the time step is selected according to the stroke frequency. Therefore, the positive displacement pump can take the adjustment signal into account particularly quickly.

[0086] The time step is preferably proportional to the current reciprocal of the stroke frequency. The reciprocal of the stroke frequency can be called the stroke cycle. Therefore, a new adjustment variable for the stroke amplitude can be pre-defined for each stroke cycle or any number of stroke cycles, thereby allowing the fluid pressure or flow rate to be adapted to the current measurement value particularly quickly and accurately.

[0087] In another advantageous embodiment, a hydraulic energy storage element may be arranged on the suction side of the positive displacement pump, and the device may have another hydraulic energy storage element arranged on the pressure side of the positive displacement pump. This embodiment can reduce pressure pulsation and volumetric flow rate pulsation on both the suction and pressure sides.

[0088] Alternatively or additionally, to achieve the aforementioned objective, according to the invention, a set of independent claims is provided, relating to a method for determining the hydraulic resonant frequency of the apparatus as described above. In particular, to achieve the aforementioned objective, according to the invention, a method of the type described at the beginning for determining the hydraulic resonant frequency is proposed to traverse a range of stroke frequencies of the positive displacement pump, wherein at each stroke frequency, a measured value of a flow parameter is detected.

[0089] As mentioned above, the hydraulic resonant frequency can be approximated by the stroke frequency at which the maximum pulsation of pressure and / or volumetric flow rate is measured. By determining the hydraulic resonant frequency in this way, it can be taken into account in the control and avoided when operating the device.

[0090] Alternatively or additionally, to achieve the above objectives, features of the parallel independent claims are provided, which relate to a control unit. In particular, according to the invention, the control unit is configured to control the apparatus as described above, such that the methods for conveying fluid or for determining the hydraulic resonant frequency as described above are performed. The aforementioned advantages can be achieved through this control unit.

[0091] The invention will now be described in more detail based on embodiments, but the invention is not limited to these embodiments. Further variations and embodiments are derived by combining features of one or more of the claims with each other and / or with one or more features of the embodiments and / or the foregoing variations of the apparatus and method according to the invention.

[0092] In the attached diagram: Figure 1 An apparatus for conveying fluid is shown, wherein the measured flow parameter is pressure. Figure 2 A variation of the device is shown, in which multiple pressure sensors are arranged in different locations. Figure 3 A variation of the device is shown, in which the measured flow parameter is flow rate. Figure 4 A variation of the device is shown, in which multiple flow sensors are arranged in different locations. Figure 5 It shows Figure 1 The electrical equivalent circuit diagram of the hydraulic device shown is as follows: Figure 6 A diaphragm pump according to the present invention is shown. Figure 7 A diaphragm pump according to the invention, having two pump chambers, is shown. Figure 8 Another diaphragm pump according to the invention, having two pump chambers, is shown. Figure 9 Another diaphragm pump according to the invention is shown, having two pump chambers and only two hydraulic energy storage elements.

[0093] exist Figure 1 In this device 1, there is a positive displacement pump 3 equipped with a linear drive mechanism M. The positive displacement pump is designed as a diaphragm pump 16. Here, the linear drive mechanism M is a direct drive mechanism that can drive the stroke element 17. In order to better control the positive displacement pump 3, a position sensor 10 is provided, by means of which the current stroke amplitude h of the positive displacement pump 3 can be detected.

[0094] Positive displacement pump 3 is connected to a first fluid reservoir 13 via pipe 5 on its suction side 11, from which fluid 2 is delivered. On the pressure side 12, positive displacement pump 3 is connected to a second fluid reservoir 14 via pipe 5, into which fluid 2 is delivered. Fluid 2 is a liquid.

[0095] Furthermore, a hydraulic energy storage element 4 and a throttling orifice 8 are respectively arranged in the pipes 5 on both sides 11 and 12 of the positive displacement pump 3. The hydraulic energy storage element 4 has two chambers, which are separated from each other by a partition layer 9.

[0096] Since the positive displacement pump 3 undergoes both suction and discharge processes in each stroke cycle, the delivery rate Q of the positive displacement pump 3 is... p It exhibits pulsation. Therefore, the delivery rate Q p It's not stable, but pulsating. The conveying rate Q is controlled by the hydraulic energy storage element 4. p Compensation is performed to ensure that the incoming flow Q... u and discharge flow rate Q d It has reduced pressure pulsation and volumetric flow rate pulsation.

[0097] The orifice 8 increases the flow resistance in the pipe 5. Positioned on the pressure side 12, the orifice 8 ensures that fluid 2 does not flow directly in the direction of the second fluid reservoir 14, thus bypassing the hydraulic energy storage element 4. Due to the flow resistance created by the orifice 8, fluid 2 more readily flows into the hydraulic energy storage element 4 first, which compensates for pressure and volumetric flow rate fluctuations. Therefore, the effectiveness of the hydraulic energy storage element 4 is supported by the orifice 8.

[0098] The situation is similar on the suction side 11. The flow resistance of the fluid 2 in the pipe 5 is increased by the orifice 8. Therefore, a larger proportion of the fluid 2 drawn in by the positive displacement pump 3 comes from the hydraulic energy storage element 4 on the suction side, while a smaller proportion comes from the pipe 5 upstream of the orifice 8. This makes the flow conditions in the pipe 5 upstream of the orifice 8 more balanced, as the pressure and volumetric flow rate fluctuations generated by the positive displacement pump are compensated by the hydraulic energy storage element 4. Here, the orifice 8 supports the operation of the hydraulic energy storage element 4.

[0099] A sensor 7 is arranged on the pressure side 12 of the positive displacement pump 3, and the pressure p can be measured using this sensor. m The measured pressure p m The data is transmitted to control unit 6, where the measured value is compared with the target pressure p. ref Compare them.

[0100] Based on the comparison results, the control unit 6 pre-determines new adjustment variables for the stroke amplitude h and stroke frequency f of the positive displacement pump 3. Here, the adjustment variables are recalculated for each time step Δt. Here, the time step Δt corresponds to the stroke cycle of the positive displacement pump 3, which is the reciprocal of the stroke frequency f. Therefore, for each new stroke cycle, a new stroke amplitude h and a new stroke frequency f are pre-determined.

[0101] The described device has a hydraulic resonant frequency. The hydraulic resonant frequency can be calculated or determined empirically. For empirical determination, the available stroke frequencies f of the positive displacement pump 3 can be traversed during a test run. At each stroke frequency f, the pressure p is detected by means of sensor 7. mRecord these measurements. When evaluating these measurements, the hydraulic resonant frequency can be identified as the stroke frequency f at which the maximum pressure pulsation is measured.

[0102] For subsequent operation of device 1, control unit 6 is configured such that the stroke frequency f is always higher than the hydraulic resonant frequency. This is to adjust the required pressure p. ref The control of the stroke amplitude h is prioritized. However, to maximize flexibility in control device 1, the stroke frequency f is also controlled, but only within a range above the hydraulic resonant frequency. Here, a minimum value for the stroke frequency f is set. When this minimum value is reached, the stroke frequency f no longer decreases, and from this point onward, control is achieved solely through the stroke amplitude h, which can be controlled within a range of 100 times, thus covering a very wide range of available pressure and / or flow.

[0103] Furthermore, the stroke frequency f is maintained within a range close to the mechanical resonant frequency of the positive displacement pump 3, which is designed as a diaphragm pump 16. Therefore, the energy consumption required to transport fluid 2 is minimized.

[0104] However, before the positive displacement pump 3 can transfer fluid 2 (which is liquid) from the first fluid reservoir 13 to the second fluid reservoir 14, the positive displacement pump 3 must operate in gas operation mode. This is necessary because when the device 1 is started, the pipeline 5 is not yet filled with liquid fluid 2, but with gas (in this case, air). Therefore, liquid fluid 2 must first be drawn from the first fluid reservoir 13.

[0105] For this purpose, the positive displacement pump 3 operates at its maximum stroke amplitude h. This is advantageous for compressible media such as air, as the clearance volume in the positive displacement pump 3 is minimized in this case. Alternatively or additionally, the neutral position of the stroke movement can be adjusted to minimize the clearance volume. This allows the maximum stroke volume to be provided, thereby providing a larger vacuum for conveying air and drawing in liquid fluid 2. Once liquid fluid 2 is drawn in, the stroke amplitude h is variablely controlled to adjust the required pressure p. m .

[0106] Figures 2 to 4 It shows Figure 1 A variation of the embodiment. Here, the corresponding device 1 has the same basic configuration as described above and can operate in a similar manner.

[0107] Figure 2 A variation of device 1 can be seen, in which a device for detecting pressure p can be seen. m The four possible positions of sensor 7.

[0108] The sensor 7 has two possible locations on the suction side 11 of the positive displacement pump 3. This allows for the measurement of the pressure p of the fluid 2 before it enters the positive displacement pump 3. m Therefore, pressure p can also be applied in this region. m Adjustments are made. Specifically, the pressure p... m It can remain below the maximum value and / or above the minimum value. The first position of sensor 7 is located in front of the throttle orifice 8. The second position is arranged in the hydraulic energy storage element 4 on the suction side, and measures the offset of the separator layer 9. The pressure p present in the hydraulic energy storage element 4 can then be calculated from the measured offset. m Alternatively, a conventional pressure sensor can be installed in the hydraulic energy storage element 4.

[0109] Similarly, two other possible locations for sensor 7 are located on the pressure side 12 of the positive displacement pump 3, one in the hydraulic energy storage element 4 on the pressure side and the other behind the throttle orifice 8 on the pressure side.

[0110] Depending on the desired operating mode, one or more sensors 7 can be placed at one or more locations.

[0111] Figure 3 The embodiments and Figure 1 The embodiment is the same, but sensor 7 does not measure pressure p. m It's not about traffic Q m The measured value is transmitted to control unit 6, which compares the measured value with a pre-defined reference value Q. ref A comparison is made. Based on the comparison results, the adjustment variables for updating the pre-given stroke amplitude h and stroke frequency f of the positive displacement pump 3 are adjusted at a time step Δt.

[0112] When a positive displacement pump 3 is needed to provide a specific target flow rate Q ref This device 1 is particularly suitable at that time.

[0113] exist Figure 4 You can see Figure 3 A variation of the embodiment. Here, another mounting location for sensor 7 is provided so that flow rate Q can also be measured on the suction side 11 of the positive displacement pump 3. m Therefore, the flow rate Q on the suction side 11 can also be adjusted. m Sensor 7 can be arranged at one of two mounting locations. Alternatively, two sensors 7 can be used, thereby, for example, detecting the flow rate Q on the suction side 11. m The flow rate Q on pressure side 12 is greater than m At that time, leaks in pipe 5 can be detected.

[0114] Figure 5 It shows Figure 1 The diagram shows the electrical equivalent circuit of the hydraulic system. To mathematically describe the characteristics of the hydraulic system, additional electrical diagrams and common components (resistors, capacitors, inductors, current sources) can be used to represent the system. Because... Figure 1 The structure of the device shown is symmetrical, therefore Figure 5 Only the pressure side is shown.

[0115] Here, Figure 1 and Figure 5 The hydraulic and electrical symbols in the diagram represent the various components of the system. Hydraulic line 5 corresponds to a series circuit of resistor (Rd) and inductor (Ld). Orifice 8 corresponds to resistor (Ro). Hydraulic energy storage element 4 corresponds to capacitor (Ca). A reservoir with an interface located below the liquid level corresponds to grounding 15. Positive displacement pump 3 corresponds to current source (Ap).

[0116] This analogy with electrical engineering suggests that hydraulic systems possess specific resonant characteristics, which depend on the capacitance of the energy storage element, the resistance of the pipeline, and the possible throttling orifices and other hydraulic components and their connections.

[0117] Based on this analogy, electrical engineers can, for example... Figure 5 The equivalent circuit diagram constructed as shown determines the resonance characteristics of the hydraulic system. The information thus determined, particularly regarding the resonance frequency, can then be used according to the invention to control the positive displacement pump by controlling the stroke amplitude and, if necessary, the stroke frequency, thereby avoiding the resonance frequency.

[0118] Figure 6 A diaphragm pump 16 according to the invention is shown. The diaphragm pump can be integrated into a device 1 for conveying fluid 2 and has a pump chamber 19. The pump chamber 19 is defined by a diaphragm 18. The diaphragm 18 is connected to a stroke element 17.

[0119] In addition, Figure 6 The coil winding 20 of the linear drive mechanism of the diaphragm pump 16 can be seen. In this embodiment, the linear drive mechanism therefore includes a rigid coil armature and a movable rotor (stroke element 17) having a permanent magnet. When current flows through the coil winding 20, the stroke element 17 is driven to move, thereby performing a suction or discharge process in the pump chamber 19 according to the impact direction of the stroke element 17.

[0120] The diaphragm pump 16 includes two hydraulic energy storage elements 4. These elements are connected to the suction valve 21 or discharge valve 22 of the diaphragm pump 16 via conduits 5. These conduits 5 are short channels 27 that connect the valve chamber 26 of the diaphragm pump 16 and the cavity 25 of the hydraulic energy storage element 4 to each other. Here, the channels 27 lead directly and without connectors into the respective cavities 25. The diaphragm pump 16 has a pump housing 28, which, in addition to the hydraulic energy storage elements 4, a stroke element 17, a diaphragm 18, and a linear drive mechanism M.

[0121] The suction valve 21 and the discharge valve 22 are connected to the pump chamber 19 through the pipeline 5.

[0122] Each hydraulic energy storage element 4 has a partition layer 9, which in this example is an elastomeric plate. In this example, the hydraulic energy storage element 4 has only one cavity 25, which is in contact with the fluid 2 to be transported. Since the hydraulic energy storage element 4 shown operates at atmospheric pressure, another cavity for each hydraulic energy storage element 4 is omitted. Therefore, each partition layer 9 only separates the cavity 25 containing the fluid 2 of the hydraulic energy storage element 4 from the surrounding environment.

[0123] A throttling orifice 8 is arranged at the inlet 23 of the diaphragm pump 16, in front of the hydraulic energy storage element 4, on the suction side 11 of the diaphragm pump 16. This improves the damping characteristics of the hydraulic energy storage element 4 on the suction side.

[0124] On the pressure side 12, a throttling orifice 8 is also arranged at the outlet 24 of the diaphragm pump behind the hydraulic energy storage element 4. This also improves the damping characteristics of the hydraulic energy storage element 4 on the pressure side.

[0125] Figure 7 A variation of the diaphragm pump 16 according to the invention is shown, which can be integrated into a device 1 for conveying fluid 2 and has two pump chambers 19, 19'. Pump chambers 19, 19' are defined by diaphragms 18, 18', respectively.

[0126] Two diaphragms 18, 18' are interconnected via a stroke element 17. Thus, pump chambers 19, 19' are coupled together. This means that when one of pump chambers 19, 19' is in the suction or drawing phase, the other pump chamber 19, 19' is in the discharge or pressure phase.

[0127] exist Figure 7 In the view shown, the stroke element 17 of the diaphragm pump 16, which is a positive displacement pump 3, is in a stationary position. For this reason, the pump chambers 19 and 19' have the same volume.

[0128] In addition, Figure 7The coil winding 20 of the linear drive mechanism can also be seen. In this embodiment, the linear drive mechanism therefore includes a rigid coil armature and a movable rotor (stroke element 17) having a permanent magnet. When current flows through the coil winding 20, the stroke element 17 is driven to move, thereby performing the suction or discharge process in the pump chambers 19 and 19' in a phase-shifted manner, respectively.

[0129] In this embodiment, the diaphragm pump 16 includes four hydraulic energy storage elements 4. These elements are connected to the suction valve 21 or the discharge valve 22 of the diaphragm pump 16 via pipelines 5, and the suction valve 21 or the discharge valve 22 is connected to the pump chambers 19, 19' via pipelines 5.

[0130] Additionally, the hydraulic energy storage element 4 is connected to the inlet 23 or outlet 24 of the diaphragm pump 16 via conduits 5. These conduits 5 are short channels 27 that connect the valve chamber 26 of the diaphragm pump 16 and the cavity 25 of the hydraulic energy storage element 4 to each other. Here, the channels 27 lead directly into the respective cavities 25 without any connecting parts. The diaphragm pump 16 has a pump housing 28, which in addition to the hydraulic energy storage element 4, the stroke element 17, the diaphragm 18, and the linear drive mechanism M.

[0131] Each hydraulic energy storage element 4 has a separating layer 9, which in this example is an elastomeric plate. In this example, the hydraulic energy storage element has only one cavity that contacts the fluid 2 to be transported. Since the hydraulic energy storage elements 4 shown operate at atmospheric pressure, another cavity for each hydraulic energy storage element 4 is omitted. Therefore, each separating layer 9 only separates the cavity containing the fluid 2 of the hydraulic energy storage element 4 from the surrounding environment.

[0132] On the suction side 11 of the diaphragm pump 16, a throttling orifice 8 is arranged in the pipeline 5 before the inlet opening of the hydraulic energy storage element 4. This improves the damping characteristics of the hydraulic energy storage element 4.

[0133] On the pressure side 12, a throttling orifice 8 is also arranged in the pipeline 5 at the outlet opening of the hydraulic energy storage element 4. This also improves the damping characteristics of the hydraulic energy storage element 4 on the pressure side.

[0134] Figure 8 A diaphragm pump 16 according to the invention is shown, which can be integrated into a device 1 for conveying fluid 2, and its structure is similar to... Figure 7 The structure is the same as that of the diaphragm pump 16. The only difference is that the throttle orifice 8 is not like... Figure 7 In the case described above, it is arranged in front of the inlet and outlet openings of the hydraulic energy storage element 4.

[0135] Conversely, a throttling orifice 8 is arranged at the inlet 23 and the outlet 24 of the diaphragm pump 16, respectively. Thus, the two hydraulic energy storage elements 4 on the suction side 11 can be connected via pipe 5 to form a single large hydraulic energy storage element. Similarly, on the pressure side 12, two hydraulic energy storage elements 4 can be connected via pipe 5. This can have a beneficial effect on the damping characteristics of the hydraulic energy storage elements 4.

[0136] Figure 9 The diaphragm pump 16 according to the present invention can be integrated into a device 1 for conveying fluid 2. The structure of the diaphragm pump 16 is similar to... Figure 7 The structure of the diaphragm pump 16 is the same. The only difference is that the diaphragm pump 16 does not have four hydraulic energy storage elements 4, but only two hydraulic energy storage elements 4.

[0137] One of the hydraulic energy storage elements 4 is arranged on the suction side 11 of the diaphragm pump 16. (According to...) Figure 8 The embodiments differ, wherein the partition layer 9 of the hydraulic energy storage element 4 is arranged on the lateral side of the diaphragm pump 16. Figure 9 In the illustrated embodiment, the separator layer 9 is arranged on the longitudinal side of the diaphragm pump 16. The "lateral side" is the side of the diaphragm pump 16 that forms the end of the diaphragm pump 16 in the stroke direction. The "longitudinal side" is the side located beside the stroke element 17. The separator layer 9 is divided into two sections, which are preferably spatially separated from each other with respect to the inlet 23 of the diaphragm pump 16. Therefore, fluid 2 reaches the hydraulic energy storage element 4 on the suction side via the inlet 23 and the throttle orifice 8.

[0138] Another hydraulic energy storage element 4 is arranged on the pressure side 12 of the diaphragm pump 16. Here, the outlet 24 of the diaphragm pump 16 is also preferably centrally located between the two sections of the partition layer 9 of the hydraulic energy storage element 4 on the pressure side. The partition layer 9 is arranged on the lateral side of the diaphragm pump 16, which is opposite to the lateral side of the partition layer 9 of the hydraulic energy storage element 4 on the suction side. In addition, a throttle orifice 8 is also arranged at the outlet 24.

[0139] The hydraulic energy storage element 4 is connected to two pump chambers 19 and 19' via pipelines 5.

[0140] The diaphragm pump 16 can be made particularly compact by using only two hydraulic energy storage elements 4.

[0141] In the apparatus 1 and method for conveying fluid 2, a positive displacement pump 3, particularly a diaphragm pump 16, with an adjustable stroke amplitude h is used, and the stroke amplitude h of the positive displacement pump 3 can be controlled by a control unit 6. The stroke frequency f of the positive displacement pump 3 can be controlled such that this stroke frequency is outside the hydraulic resonant frequency of the apparatus 1. The stroke amplitude h of the positive displacement pump 3 can be controlled based on measured flow parameters.

[0142] Reference tag list 1 device 2. Fluid 3 Positive displacement pumps 4. Hydraulic energy storage element 5. Piping 6 Control Unit 7 sensors 8 throttle orifices 9 (4) separator layer 10 Position Sensors 11 (3) suction side 12 (3) pressure side 13 First Fluid Storage 14 Second fluid storage tank 15 Grounding 16 Diaphragm Pumps 17-stroke element 18 (16) diaphragm 19 (of 16) pump chamber 20 (16) coil windings 21 Suction valve 22 Discharge valve 23 (of 16) entrance 24 (of 16) exports 25 chambers 26 Valve Chamber 27 channels 28 Pump casing h Stroke amplitude f Stroke frequency M linear drive mechanism p m (Measured) pressure p ref Target pressure Q d (Leaving 3) discharge flow Q m (Measured) flow rate Q p (3) conveying rate Q ref Target traffic Q u (Entering 3) Entering traffic Δt is the time step.

Claims

1. A diaphragm pump (16), comprising: Stroke element (17) having an adjustable stroke amplitude (h). A backlash-free linear drive mechanism (M) configured as a direct drive mechanism is used to drive the stroke element (17). Hydraulic energy storage element (4); and The control unit (6) can control the stroke amplitude (h) of the stroke element (17).

2. The diaphragm pump (16) according to the preceding claim, characterized in that, The linear drive mechanism (M) is configured as an electromagnetic drive mechanism, particularly an electric drive mechanism.

3. The diaphragm pump (16) according to any one of the preceding claims, characterized in that, The hydraulic energy storage element (4) is arranged on the suction side (11) or pressure side (12) of the pump chamber (20, 20') of the diaphragm pump (16).

4. The diaphragm pump (16) according to any one of the preceding claims, characterized in that, The diaphragm pump (16) has a pump housing (28) that surrounds the hydraulic energy storage element (4) and the stroke element (17).

5. The diaphragm pump (16) according to any one of the preceding claims, characterized in that, A channel (27) is constructed between the cavity (25) of the hydraulic energy storage element (4) and the valve chamber (26) of the diaphragm pump (16), and in particular, the channel (27) extends directly and / or without connection into the cavity (25).

6. The diaphragm pump (16) according to any one of the preceding claims, characterized in that, The hydraulic energy storage element (4) is arranged on the suction side, and the diaphragm pump (16) has another hydraulic energy storage element (4) arranged on the pressure side.

7. The diaphragm pump (16) according to any one of the preceding claims, characterized in that, The diaphragm pump (16) has two pump chambers (19, 19') defined by diaphragms (18, 18') respectively, wherein the two diaphragms (18, 18') are connected to each other via the stroke element (17).

8. The diaphragm pump (16) according to any one of the preceding claims, characterized in that, The diaphragm pump (16) has at least four hydraulic energy storage elements (4), wherein two hydraulic energy storage elements (4) are respectively arranged on the suction side (11) of the pump chamber (19, 19') and two hydraulic energy storage elements (4) are respectively arranged on the pressure side (12) of the pump chamber (19, 19').

9. A device (1) for conveying fluid (2), comprising: Positive displacement pump (3), particularly diaphragm pump (16), preferably constructed according to any one of the preceding claims, the positive displacement pump having an adjustable stroke amplitude (h). Hydraulic energy storage element (4). Pipeline (5), and Control unit (6), which is connected to the positive displacement pump (3), Its features are, The stroke amplitude (h) of the positive displacement pump (3) can be controlled by the control unit (6), and the control unit (6) is configured such that the stroke frequency (f) of the positive displacement pump (3) is outside the hydraulic resonant frequency of the device.

10. The apparatus (1) according to the preceding claim, characterized in that, The control unit (6) is configured in the operating mode such that the stroke frequency (f) is constant, or the stroke frequency (f) is unchangeable, and / or the stroke frequency (f) is higher than the hydraulic resonance frequency.

11. The apparatus (1) according to any one of the preceding claims, characterized in that, The control unit (6) is configured such that, in the operating mode, the stroke frequency (f) is not lower than the minimum value, and in particular, the stroke amplitude (h) decreases first when the delivery rate of the fluid (2) decreases, and the stroke frequency (f) decreases only when the minimum value of the stroke amplitude (h) is reached.

12. A device (1) for conveying fluid (2), particularly a device (1) for conveying fluid (2) according to any one of the preceding claims, comprising: Positive displacement pump (3), particularly diaphragm pump (16), preferably constructed according to any one of claims 1 to 8, having an adjustable stroke amplitude (h). Hydraulic energy storage element (4). Pipeline (5), Sensor (7) is used to measure the flow parameters of the fluid (2), and The control unit (6) is connected to the positive displacement pump (3) and the sensor (7). Its features are, The stroke amplitude (h) of the positive displacement pump (3) can be controlled by the control unit (6) based on the flow parameters measured by the sensor (7).

13. The apparatus (1) according to the preceding claim, characterized in that, The flow parameter is pressure (p) m ) and / or flow (Q m ).

14. The apparatus (1) according to any one of the preceding two claims, characterized in that, The sensor (7) is designed and arranged such that the offset of the partition layer (9) of the hydraulic energy storage element (4) can be measured by the sensor (7), and the pressure (p) can be determined based on the measured offset, particularly by the control unit (6). m ).

15. The apparatus (1) according to any one of the preceding claims, characterized in that, The stroke frequency (f) of the positive displacement pump (3) can be controlled by the control unit (6) based on the flow parameters measured by the sensor (7).

16. The apparatus (1) according to any one of the preceding claims, characterized in that, The pipeline (5) has a throttling orifice (8) to increase flow resistance.

17. The apparatus (1) according to any one of the preceding claims, characterized in that, The hydraulic energy storage element (4) is arranged on the suction side (11) of the positive displacement pump (3), and the device (1) has another hydraulic energy storage element (4) arranged on the pressure side (12) of the positive displacement pump (3).

18. The apparatus (1) according to any one of the preceding claims, characterized in that, The stroke amplitude (h) can be controlled within a range of at least 10 times, preferably at least 100 times.

19. The apparatus (1) according to any one of the preceding claims, characterized in that, The control unit (6) is configured such that the stroke frequency (f) is between 0.7 and 1.4 times the mechanical resonant frequency of the positive displacement pump (3), and in particular, the stroke frequency (f) is kept constant.

20. The apparatus (1) according to any one of the preceding claims, characterized in that, The positive displacement pump has a linear drive mechanism (M), and in particular, the linear drive mechanism (M) is an electromagnetic drive mechanism and / or a direct drive mechanism.

21. The apparatus (1) according to any one of the preceding claims, characterized in that, The stroke position of the positive displacement pump (3) can be detected by a position sensor (10), and the position sensor (10) is connected to the control unit (6).

22. The apparatus (1) according to any one of the preceding claims, characterized in that, The positive displacement pump (3) can operate with clearance volume, which can transport gaseous media in addition to liquids, and the control unit (6) can adjust the stroke amplitude (h) and / or the neutral position of the stroke element (17) according to the clearance volume.

23. The apparatus (1) according to any one of the preceding claims, characterized in that, The control unit (6) is configured to control the device (1) to perform the method according to any one of the following claims.

24. A method for conveying fluid (2) by means of a device (1), said device being particularly the device according to any one of the preceding claims, said device comprising: Positive displacement pump (3), particularly diaphragm pump (16), preferably constructed according to any one of claims 1 to 8, having an adjustable stroke amplitude (h). Hydraulic energy storage element (4), and Pipeline (5), Its features are, Controlling the stroke amplitude (h) of the positive displacement pump (3), in particular, wherein the stroke frequency (f) of the positive displacement pump (3) is kept outside the hydraulic resonant frequency of the device.

25. A method for conveying fluid (2) by means of a device (1), said device being particularly the device according to any one of the preceding claims relating to the device, said device comprising: Positive displacement pump (3), particularly diaphragm pump (16), preferably constructed according to any one of claims 1 to 8, having an adjustable stroke amplitude (h). Hydraulic energy storage element (4), and Pipeline (5), Its features are, The flow parameters of the fluid are measured, and the stroke amplitude (h) of the positive displacement pump (3) is controlled according to the measured flow parameters.

26. The method according to the preceding claims, characterized in that, The stroke frequency (f) of the positive displacement pump (3) is controlled according to the measured flow parameters.

27. The method according to any one of the preceding claims, characterized in that, The stroke amplitude (h) is adjusted to its maximum value until the positive displacement pump (3) is filled with liquid, and then the stroke amplitude (h) is variably controlled.

28. The method according to any one of the preceding claims, characterized in that, A target value (p) is pre-defined for the flow parameter. ref Q ref The target value is compared with the measured value of the flow parameter, and the stroke amplitude (h) is controlled according to the comparison result, wherein the measured value is made consistent with the target value.

29. The method according to any one of the preceding claims, characterized in that, The adjustment variable of the stroke amplitude (h) is updated with a time step (Δt), wherein the time step (Δt) is selected according to the stroke frequency (f), and in particular, wherein the time step (Δt) is proportional to the current reciprocal of the stroke frequency (f).

30. The method according to any one of the preceding claims, characterized in that, The hydraulic energy storage element (4) is arranged on the suction side (11) of the positive displacement pump (3), and the device (1) has another hydraulic energy storage element (4) arranged on the pressure side (12) of the positive displacement pump (3).

31. A method for determining the hydraulic resonant frequency of the device (1) according to any one of the preceding claims, Its features are, The range of stroke frequencies (f) of the positive displacement pump (3) is traversed, wherein at each stroke frequency (f), the measured value of the flow parameter is detected.

32. A control unit (6) configured to control a diaphragm pump (16) according to any one of claims 1 or 2 and / or a device (1) according to any one of claims 3 to 16, such that the method according to any one of the preceding method claims is performed.

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