Fluid assembly

Abstract

Fluid assembly for use in a fluid system, having a control module including a processing unit for processing control commands into individual electrical control signals with individually adjustable control signal levels and a control signal level electrically connected to the processing unit, with a power unit, which has a power module for converting the control signals into individual electrical control currents as a function of the control signal levels and an output interface electrically connected to the power module, wherein the processing unit is designed to provide a first group of control signals in a first time interval which can be individually predetermined for each control signal and to provide a second group of control signals in a second time interval which can be individually predetermined for each control signal and follows the respective first time interval, wherein the first control signal and the second control signal are selected in such a way that the control currents in the first time interval are greater than the control currents in the second time interval.

Claims

1. A fluid assembly for use in a fluid system, the fluid assembly comprising a control system having a control module and a power unit, the control module comprising: an input interface for receiving control commands; a processing unit electrically connected to the input interface for processing the control commands into individual electrical control signals with individually adjustable control signal levels; and signal interface electrically connected to the processing unit for outputting the control signals, and the power unit comprising: a control interface electrically connected to the signal interface for receiving the control signals; and a plurality of electrical output stages connected to the control interface for converting the control signals into individual electrical control currents depending on the control signal levels, wherein the control system further comprises a supply interface electrically connected to the plurality of electrical output stages for feeding electrical energy into the plurality of electrical output stages, and wherein the power unit further comprises an output interface electrically connected to the plurality of electrical output stages, the output interface providing the control currents to provide an individual electrical supply to a plurality of electrical loads, and wherein the processing unit provides a first group of control signals from a first level interval in a first time interval which can be individually predetermined for each control signal, and wherein the processing unit further provides a second group of control signals from a second level interval in a second time interval which can be individually predetermined for each control signal, wherein the respective second time interval follows the first time interval and wherein first interval limit of the first level interval and second interval limit of the second level interval are selected such that the control currents in the first time interval are greater than the control currents in the second time interval.

2. The fluid assembly according to claim 1, wherein the first interval limit of the first level interval and the second interval limit of the second level interval are selected in such a way that the control currents effected by the first group of control signals are at least 200 percent greater than the control currents effected by the second group of control signals.

3. The fluid assembly according to claim 1, wherein the first level interval comprises exactly one level value for the control signal and/or that the second level interval comprises exactly one level value for the control signal.

4. The fluid assembly according to claim 1, wherein a plurality of solenoid valves are connected to the output interface, and wherein the power unit is designed to provide individual electrical control currents for each of the solenoid valves.

5. The fluid assembly according to claim 4, wherein a solenoid coil is arranged in a current path of the solenoid valve which extends between a first terminal contact and a second terminal contact.

6. The fluid assembly according to claim 1, wherein the control module has a parameter interface electrically connected to the processing unit for receiving parameterization commands, and wherein the processing unit is designed to adapt the individual electrical control signals as a function of the parameterization commands.

7. The fluid assembly according to claim 6, wherein the processing unit is designed in such a way that for each of the individual electrical control signals the first time interval and the second time interval can be determined individually on the basis of the parameterization commands.

8. The fluid assembly according to claim 6, wherein the processing unit is designed in such a way that for each of the individual electrical control signals a first control signal level can be selected from the first level interval and/or a second control signal level can be selected from the second level interval on the basis of the parameterization commands.

9. The fluid assembly according to claim 1, wherein the input interface is designed to receive control commands coded digitally as bus telegrams and/or to receive analog control commands coded by a current level or a voltage level.

10. The fluid assembly according to claim 1, wherein the control module and the power unit are arranged on a common printed circuit board, the printed circuit board being arranged in a housing to which a holder is fixed on which a plurality of solenoid valves electrically connected to the output interface are arranged along a row axis.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, the invention is explained in more detail using the enclosed drawing.

(2) FIG. 1 is a strictly schematic representation of a fluid assembly for a dispensing head of a pipetting system,

(3) FIG. 2 is a schematic representation of a first control current curve,

(4) FIG. 3 is a schematic representation of a second control current curve,

(5) FIG. 4 a schematic representation of a third control current curve, and

(6) FIG. 5 is a schematic representation of a fourth control current curve.

DETAILED DESCRIPTION

(7) A fluid assembly 1 shown in FIG. 1 purely schematically comprises a control module 2 and several solenoid valves 3 to 7 electrically connected to the control module 2. The fluid assembly 1 can be used, just as an example, in a dispensing head of a pipetting system, which is not shown in detail. The task of the fluid assembly 1 is to convert electrical control commands from an unspecified higher-level machine control system into fluid streams with which the desired dosing of fluids, especially liquids, can be performed.

(8) The task of control module 2 is to convert incoming control commands into individual control currents for the respective consumers, in particular for the solenoid valves 3 to 7.

(9) For this purpose, control module 2 comprises a control module 8 and a power unit 9, which are designed separately as shown in FIG. 1, but which may in practice also be arranged on a common, printed circuit board.

(10) The control module 8 comprises an input interface 10, a processing unit 11 electrically connected to the input interface 10, and a signal interface 12 electrically connected to the processing unit 11.

(11) The input interface 10 is designed for receiving control commands which can be provided, for example, by a higher-level machine control system, which is not shown. These control commands can be, for example, digitally coded control commands transmitted in a bus telegram 15. In addition or alternatively, the input interface 10 can also be designed for receiving analog control commands, for example in the form of voltage signals or current signals. As a pure example, the input interface 10 can receive pulse-shaped analog control commands 16 as well as analog control commands with continuous level change 17 and transmit them to the processing unit 11 via a signal line 18.

(12) The processing unit 11 can be designed as a microcontroller or microprocessor and serves to process the incoming control commands into control signals. These control signals, which are preferably analog voltage signals that can assume signal levels in a value interval between 0 Volt and 10 Volt, are provided to a signal interface 12. For example, the processing unit 11 is designed to provide five control signals, which are provided at the signal interface 12 in such a way that each of the five individual control signals can be transmitted to the power unit via an individual control signal line 20.

(13) For the electrical coupling with the processing unit 11, the power unit 9 comprises a control interface 21 to which the five control signal lines 20 are connected. The power unit 9 provides several electrical output stages 25, 26, 27, 28, 29, which may, for example, be power transistors which can be individually controlled by means of the individual control signals transmitted via the control signal lines 20. The output stages 25, 26, 27, 28, 29 are electrically connected to a supply interface 22 in addition to an electrical connection to the respective individual control signal line 20. The supply interface 22 is used to provide electrical energy to the power unit 9, whereby the output stages 25, 26, 27, 28, 29 are designed in such a way that they can cause a control current to be provided at an output interface 23 depending on an individual electrical control signal provided via the respective control signal line 20. A proportional relationship between the respective individual control signal level and the resulting individual control current is preferred.

(14) The five solenoid valves 3 to 7 of the same type are connected to the output interface 23. Each of the solenoid valves 3 to 7 has a connector plug 32 which is connected to the output interface 23 via an individual connection line 31. This enables a separate control of each of the solenoid valves 3 to 7 independently of the other solenoid valves 3 to 7.

(15) As an example, each of the solenoid valves 3 to 7 exclusively contains a solenoid coil which is not shown in detail and which is electrically connected to a first connecting contact which is not shown and to a second connecting contact which is also not shown. The connecting contacts which are not shown are connected to the connecting line 31. Preferably, solenoid valve 3 to 7 does not include any additional electrical or electronic components and thus reacts in a precisely predictable manner to the actuation current provided at output interface 23 of power unit 9.

(16) Due to production-related tolerances of solenoid valves 3 to 7 and/or due to wear and tear in solenoid valves 3 to 7, different behaviour of solenoid valves 3 to 7 may occur. As an example, solenoid valves 3 to 7 are provided for the optional blocking or enabling of a fluid channel extending between an inlet port 34 and an outlet port 35 through the respective solenoid valve 3 to 7. Thus, deviations in the behaviour of the individual solenoid valves 3 to 7 lead to differences in the fluid quantity provided by the respective solenoid valve 3 to 7. These deviations can be compensated by parameterizing the individual first control signals, in particular by the individual duration of the respective first time interval, and by parameterizing the individual second control signals, in particular by the individual duration of the respective second time interval.

(17) It is provided that for the solenoid valves 3 to 7 a continuous supply of coil currents is required after a changeover from a first functional state, for example a closed state, to a second functional state, for example an open state. It is advantageous to reduce the coil current after the second functional state has been reached, since the energy requirement of solenoid valve 3 to 7 for maintaining the second functional state is lower than for switching over between the first and second functional states and undesired heating of the respective solenoid valve 3 to 7 should be avoided.

(18) For example, four different switching characteristics 40, 41, 42, 43, also known as control current characteristics, are assigned to solenoid valves 3 to 7 by corresponding parameterization of processing unit 11. These switching characteristics 40, 41, 42, 43, which can preferably be freely parameterized for each solenoid valve 3 to 7 and which are described in more detail in connection with FIGS. 2 to 5 below, are symbolized by the respective bar diagrams 45 to 49.

(19) As an example, the bar diagram 45 shows a first bar section 50 and a second bar section 51. The first bar section 50 symbolizes the first time interval, which can be set by parameterization, in which the processing unit 11 provides a first control signal. The second bar section 51 symbolizes the second time interval, which can be set by parameterization, in which the processing unit 11 provides a second control signal.

(20) FIGS. 2 to 5 show diagrams with switching characteristics 40, 41, 42 and 43, where a current flow I [ampere] is shown over the time t [seconds]. The respective switching characteristics 40, 41, 42 and 43 are influenced by the parameterization of the processing unit 11, which is represented by the bar graphs 45 to 49 described above.

(21) In the case of switching characteristic 40 as shown in FIG. 2, it is intended that, starting from a disappearing coil current in the time span between the points in time t0 and t1 from point in time t1 to point in time t2, a coil current I2 is provided which, in the respectively assigned solenoid valve, leads to a movement of a valve member between a first functional position and a second functional position. When maintaining the second functional position for the valve member the solenoid coil of solenoid valve 3 to 7, which is also not shown in detail, has a lower energy requirement compared to the switching movement, therefore the coil current is reduced to I1 starting with t2. The coil current I1 is maintained until the respective solenoid valve 3 to 7 is switched off at t4.

(22) Accordingly, a first time interval is provided for the control of a solenoid valve 3 to 7 with switching characteristic 40 according to FIG. 2, which lasts from t1 to t2 and during which the control current I2 is provided. A second time interval is provided, which extends from t2 to t4 and which immediately follows the first time interval. During the second time interval the drive current is maintained at the level of I1. Subsequently, solenoid valve 3 to 7 is switched off due to the expiration of the total switching time provided as the sum of the first time interval and the second time interval and adjustable by parameterizing the two time intervals.

(23) Deviating from this, the representation of the switching characteristic 41 as shown in FIG. 3 provides that the first control current I2 is maintained between time t1 and time t3, while the second control current is maintained from time t3 to time t5. Thus the switching characteristic according to FIG. 2 differs from the switching characteristic according to FIG. 1 not only in the length of the total switching time, but also in the length of time during which the higher control current I2 is provided within this total switching time.

(24) In the case of switching characteristic 42 as shown in FIG. 4, the same total switching time for providing the control current is provided as in the case of switching characteristic 41 as shown in FIG. 3, but the time interval for providing the higher control current I2 is longer than in the case of switching characteristic 41.

(25) In the representation of switching characteristic 43 as shown in FIG. 5, it is intended that the first control current I2 is provided at time t2 and is maintained until time t4, while the second control current is maintained from time t4 to time t5. Thus the switching characteristic according to FIG. 4 differs from the switching characteristic according to FIGS. 2 and 3 in the length of the total switching time and in the time at which the higher control current I2 is provided within this total switching time. Such a switching characteristic can be provided, for example, to limit a total current consumption for power unit 9. Furthermore, in the case of solenoid valves 3 to 7 switching at different speeds, this can be used to make an adjustment for the point in time at which the respective fluid quantity to be dosed is output by the respective solenoid valve 3 to 7.

(26) The switching characteristics as shown in FIGS. 2 to 5 can each be specified by parameterizing the processing unit 11, whereby this parameterization can be carried out via the parameterization interface 36. Preferably, it is intended that during parameterization, the first time interval and the second time interval can be defined individually for each of the solenoid valves 3 to 7 and thus a resulting in individual total switching times for the respective solenoid valves 3 to 7. In addition, a switching time can also be defined after the arrival of an externally provided switching signal for each of the individual electrical control signals, in order, for example, to realize the switching delay described in connection with FIG. 5. A parameterization of the first time interval and the second time interval can, for example, be carried out in steps which are smaller by a factor of 50 to 1000 than the respective total switching time.

(27) As an example, a parameterization device not shown in detail, e.g. a personal computer, on which parameterization software is executed, can be connected to parameterization interface 36.

(28) By means of the parameterization software, it is possible, for example, by specifying a type designation for the respectively connected solenoid valve 3 to 7 using a corresponding database, to make a default setting for the parameters which determines the duration of the first and the second time interval and, if necessary, also the amount of the respective signal level in the time intervals.

(29) Furthermore, user inputs can be made to influence the individual parameters, i.e. in particular the duration of the first and second time intervals and, if necessary, also the amount of the respective signal level in the time intervals, and thus to set the desired valve function as required. In addition, it can also be provided that the number of switching cycles for the respective solenoid valve 3 to 7 is stored in the processing unit 11 and, if necessary, an automatic adjustment of the first and second time intervals is carried out depending on an assumed wear behaviour of the respective solenoid valve 3 to 7.