Method for controlling an electromagnetically actuated fluid pump

Abstract

Method (100) for controlling an electromagnetically actuated fluid pump (1), wherein the fluid pump (1) has an axially movable pump piston (3) for displacing and conveying a coolant and / or lubricant, wherein a coil (2', 2") is arranged in the region of each of the two axial ends of the pump piston (3), which together with the pump piston (3) form a solenoid and thus the pump piston (3) is electromagnetically actuated on both sides, wherein a delivery volume flow rate (V) of the fluid pump (1) is controlled by varying the stroke of the pump piston (3) by varying the amplitude of current pulses of a current profile applied to the respective coil (2', 2"), wherein the necessary current profiles are stored in a control unit and wherein a stroke frequency (f) is kept constant over a defined range of the delivery volume flow rate (V), wherein three operating frequencies are defined, namely a low,a medium and a high stroke frequency (f), wherein low delivery volume flows (V) are set at the low stroke frequency (f) by varying current values ​​(i1, i2) and a current pulse duration (t1, t2) of the current profile, and higher delivery volume flows (V) are controlled according to the same principle, but at the medium or high stroke frequency and with higher and different current values ​​(i1, i2).

Description

Field of invention

[0001] The present invention relates to a method for controlling an electromagnetically actuated fluid pump, wherein the fluid pump has an axially movable pump piston for displacing and conveying a cooling and / or lubricating medium, wherein a coil is arranged in the region of each of the two axial ends of the pump piston, which forms a lifting magnet with the pump piston and thus the pump piston can be electromagnetically actuated on both sides, wherein a delivery volume flow of the fluid pump is controlled by varying the stroke of the pump piston. State of the art

[0002] Electromagnetically actuated piston pumps known according to the state of the art comprise an electromagnetic coil, an armature formed in, through, or with the piston of the fluid piston pump, and a mechanical return spring. Depending on the pump design, either the suction-side or the discharge-side piston stroke is executed by releasing the energy stored in the return spring. Such piston pumps are used in automotive applications as metering pumps for low-viscosity media, for example, as fuel delivery pumps for auxiliary heaters and parking heaters, or as AdBlue delivery pumps. The delivery flow rates in these applications are limited to a few liters per hour.

[0003] Another well-known application is its use as an electric auxiliary oil pump for automatic transmissions with a start-stop function. This pump is also used for very small flow rates.

[0004] The method for operating such electromagnetically actuated piston pumps is limited to controlling or regulating the current profile of an electromagnetic coil.

[0005] German patent application DE 10 2007 017 731 A1 describes, for example, a pump comprising an electromagnet, a return mechanism, working chambers, an anchoring device or a piston, and a control device for activating the electromagnet. The anchoring unit is arranged between the electromagnet and the return mechanism. The anchoring unit is pulled or pushed by the electromagnet and separates one working chamber from the other in a liquid-tight manner. The control device controls the electromagnet by means of pulse-width modulation.

[0006] German patent application DE 10 2012 023 902 B3 describes, for example, a method for operating a hydraulic system to supply hydraulic consumers on a plastic injection molding machine. This method includes a pump exhibiting a volumetric delivery characteristic that leads to cyclic pulsations and a servomotor with multiple poles that also exhibit cyclic pulsations. The pressure at the hydraulic consumer is measured and fed as an actual value to a pressure control system, which adjusts the servomotor to a setpoint pressure at the hydraulic consumer based on a predefined pressure profile. The cyclic pressure pulsation is minimized by using a rotary encoder to measure the rotation angle of the pump and / or servomotor, correlating this with the cyclic pulsations, and then calculating a correction value or function. This correction value or function is then transmitted to the pressure control system to regulate the setpoint pressure.Alternatively or additionally, in a hydraulic system, this is also achieved by using, as a correction means for pressure control and subordinate to this for taking pulsations into account, the number of components of the pump leading to the cyclic pulsations and the number of components of the servomotor triggering cyclic pulsations are equal to or multiples of the other. Summary of the invention

[0007] It is an object of the invention to provide an improved method for controlling an electromagnetically actuated fluid pump, namely a double-coil piston pump, which in particular makes it possible to achieve high flow rates.

[0008] This need can be met by the subject matter of the present invention according to independent claim 1. Advantageous embodiments of the present invention are described in the dependent claims.

[0009] The method according to the invention serves to control an electromagnetically actuated fluid pump, wherein the fluid pump has an axially movable pump piston for displacing and conveying a cooling and / or lubricating medium, wherein a coil is arranged in the region of each of the two axial ends of the pump piston, which forms a lifting magnet with the pump piston and thus the pump piston can be electromagnetically actuated on both sides.

[0010] According to the invention, the flow rate of coolant and / or lubricant in the fluid pump is controlled by varying the stroke of the pump piston, namely by varying the axial deflection of the pump piston.

[0011] According to the invention, the height of current pulses of a current profile with which the respective coil is acted upon is varied, whereby the frequency is kept constant over a defined range of the conveying volume flow.

[0012] According to the invention, the necessary current profile parameters are stored in a control unit.

[0013] Furthermore, according to the invention, three operating frequencies are defined, namely a low, a medium and a high stroke frequency f in relation to each other. These stroke frequencies f are optimally selected with regard to “NVH” (noise, vibration, harshness) and can differ depending on the application area of ​​the fluid pump.

[0014] Low flow rates are achieved according to the invention by varying the current values ​​and the current pulse duration (time interval) of the current profile at a low stroke frequency. Higher flow rates are controlled according to the same principle, but at a medium or high stroke frequency and with higher and different current values.

[0015] The advantage of regulating the flow rate by varying the stroke is that only operating frequencies with optimal "NVH" characteristics can be selected.

[0016] In a non-inventive embodiment of the method, the delivery volume flow rate of the fluid pump is controlled by varying the stroke frequency of the pump piston, wherein the two coils of the fluid pump are operated via a power output stage with pulse width modulation.

[0017] In a further embodiment of the method not according to the invention, the delivery volume flow of the fluid pump is controlled by varying the stroke frequency of the pump piston, wherein a current profile for a stroke of the pump piston is additionally modified depending on the prevailing operating conditions. This involves controlling overexcitation and / or feedforward control of the respective coil of the solenoid. Furthermore, and not according to the invention, operating-dependent current profile parameters are stored in a control unit. Brief description of the drawings

[0018] The invention is described below by way of example with reference to the drawings. Fig. Figure 1 shows a hydraulic circuit diagram of an electromagnetically actuated double-coil piston pump. Fig. Figure 2 shows an isometric view of an exemplary embodiment of an electromagnetically actuated double-coil piston pump. Fig. Figure 3 schematically shows a first embodiment for the interconnection of the two coils of a double-coil piston pump according to Fig. 1 and Fig. 2. Fig. Figure 4 schematically shows a second design variant for the interconnection of the two coils of a double-coil piston pump according to Fig. 1 and Fig. 2. Fig. Figure 5 shows, by way of example, the relationship between the delivery volume flow rate and the stroke frequency of a twin-coil piston pump according to Fig. 1 and Fig. 2. Fig. Figure 6 shows an exemplary current profile for an electromagnetically actuated double-coil piston pump according to Fig. 1 and Fig. 2. Fig. Figure 7 shows an exemplary current profile with active feedforward control for an electromagnetically actuated double-coil piston pump according to Fig. 1 and Fig. 2. Fig. Figure 8a shows an exemplary current profile for an electromagnetically actuated double-coil piston pump according to Fig. 1 and Fig. 2 with variation of the current pulses and the current pulse duration for small flow rates. Fig. Figure 8b shows an exemplary current profile for an electromagnetically actuated double-coil piston pump according to Fig. 1 and Fig. 2. with variation of the current pulses and the current pulse duration for high flow rates. Fig. Figure 9 shows a qualitative representation of the effective current increase over time. Fig. Figure 10 shows a qualitative representation of a current ripple. Fig. Figure 11 schematically shows a flowchart of a method for controlling an electromagnetically actuated double-coil piston pump. Fig. Figure 12 shows a detailed flowchart for a first block of Fig. 11. Fig. Figure 13 shows a detailed flowchart for a second block of Fig. 11. Fig. Figure 14 shows a detailed flowchart for a third block of Fig. 11. Fig. Figure 15 shows a detailed flowchart for a fourth block of Fig. 11. Fig. Figure 16 shows a detailed flowchart for a fifth block of Fig. 11. Detailed description of the invention

[0019] In Fig. Figure 1 shows a hydraulic circuit diagram of an electromagnetically actuated fluid pump 1, namely a double-coil piston pump. Fig. Figure 2 shows an isometric view of a fluid pump 1 according to Fig. 1.

[0020] The fluid pump 1 comprises a cylinder 4 and a pump piston 3. The pump piston 3 is arranged within the cylinder 4 to define a cylindrical cavity together with the cylinder 4. The cylindrical cavity is connected to a pressure-side outlet 8 of the fluid pump 1 via a first outlet valve 6' and a second outlet valve 6" and to a suction-side inlet 9 of the fluid pump 1 via a first inlet valve 5' and a second inlet valve 5". The suction-side inlet 9 of the fluid pump 1 is fluidly connected to a cooling and / or lubricant sump (not shown).

[0021] To pump a fluid, namely the coolant and / or lubricant, such as oil, from the suction-side inlet 9 to the pressure-side outlet 8 of the fluid pump 1, the pump piston 3 can be electromagnetically actuated. For this purpose, a coil 2', 2" is arranged on each side of the pump piston 3, more precisely in the region of its two axial ends - in relation to Fig. 1 is a first coil 2' on the left side of the pump piston 3 and a second coil 2" on the right side of the pump piston 3.

[0022] The pump piston 3 and the respective coil 2', 2" each form a lifting magnet. For this purpose, a magnetic armature (not shown) is formed on, in or through the pump piston 3, which interacts electromagnetically with the respective coil 2', 2'.

[0023] By energizing the respective coil 2', 2" the pump piston 3 can be moved axially.

[0024] The direction specification “axial” corresponds to a direction along or parallel to the central longitudinal axis 7 of the pump piston 3.

[0025] Fig. 3 and Fig. Figure 4 schematically shows two possible configurations for the connection of the two coils 2', 2" of a fluid pump 1 according to Fig. 1 and Fig. 2. The two coils 2', 2" are hard-wired, i.e., permanently connected to each other. In Fig. 3. The coils 2', 2" are connected to each other via a freewheeling diode 18', 18", arranged in opposite directions, namely a first freewheeling diode 18' and a second freewheeling diode 18", and are driven by a common full-bridge circuit. The power output stage, preferably a full-bridge circuit, for driving the coils 2', 2" is not shown in the figures. These electronic components are preferably integrated in an (external) control unit (not shown), which is connected to the fluid pump 1 via a cable harness. The embodiment according to Fig. 3 has a 2-pole electrical connection 19. The wiring configuration according to Fig. 4 does not use freewheeling diodes and has a 3-pin electrical connection 20.

[0026] The exemplary fluid pump 1 is connected to the control unit (not shown) in a control-effective manner and is part of a cooling and / or lubrication system of a motor vehicle. A cooling and / or lubrication strategy for the motor vehicle can be implemented via the cooling and / or lubrication system.

[0027] The inventive method 100 is described below using the means Fig. 1 to Fig. Fluid pump 1, as described in section 4, is explained. Fig. 11 to Fig. 16 The procedure for controlling the fluid pump 100 is presented using individual flowcharts.

[0028] A first option for controlling the delivery volume flow rate V of the fluid pump 1 is a variation of the stroke frequency f of the pump piston 3.

[0029] The relationship between delivery volume flow rate V and stroke frequency f is in Fig. Figure 5 illustrates an exemplary fluid pump design, with the stroke frequency f in Hertz [Hz] plotted on the x-axis and the fluid flow rate in liters / minute [l / min] plotted on the y-axis. The stroke frequency f is varied between 1 Hz and 45 Hz. This corresponds to flow rates from 0.3 l / min to 7 l / min. The two coils 2', 2" of the fluid pump 1 are driven by a power output stage with pulse width modulation (PWM). The PWM frequency is 1 kHz to 5 kHz.

[0030] In addition to varying the stroke frequency, the current profile for a pump piston stroke is modified according to the operating conditions of the fluid pump 1. Overexcitation of a respective coil 2', 2", pre-control of a respective coil 2', 2", or a combination of both can be incorporated into such a current profile.

[0031] Fig. Figure 6 shows a first exemplary current profile for the fluid pump 1. The x-axis represents time t and the y-axis represents current I. The first coil 2' is energized with positive current values ​​(stroke) and the second coil 2" with negative current values ​​(reverse stroke). In case of overexcitation, the first current value i1 of the current profile is selected in the range of 10 A to 12 A for the exemplary fluid pump design in order to increase the dynamics of the pump piston 3. Fig. Figure 6 shows a corresponding current profile with three time intervals t1, t2, t3, namely a first time interval t1, a second time interval t2, and a third time interval t3, and associated current values ​​i1, i2, i3, namely a first current value i1, a second current value i2, and a third current value i3. The duration of the time intervals t1, t2, t3 and the current values ​​i1, i2, i3 are varied or fixed depending on the operating conditions. At higher stroke frequencies f, from approximately 10 Hz, the third time interval t3 of the current profile is shortened or omitted entirely. The operating-dependent current profile parameters are stored in the control unit.

[0032] In the case of feedforward control, the first time interval t1 of the reverse stroke current profile (negative current values) is superimposed on the third time interval t3 of the stroke current profile (positive current values). This control variant is in Fig. 7 to be seen. In Fig. Figure 7 shows time t on the x-axis and current I on the y-axis. As described for overexcitation, in feedforward control the three time intervals t1, t2, t3, as well as the three current values ​​i1, i2, i3, are varied or fixed depending on the operating conditions. Here too, the operating-dependent current profile parameters are stored in the control unit. Feedforward control is used to increase the dynamics of the pump piston 3 and to implement end-position damping of the pump piston 3.

[0033] Certain operating conditions require a combination of overexcitation and feedforward control. The control unit selects the optimal current profile, taking into account the operating conditions, the target flow rate, and the maximum possible efficiency.

[0034] A second variant for controlling the delivery volume flow rate V of the fluid pump 1 is achieved by varying the stroke of the pump piston 3, namely by varying the axial deflection of the pump piston 3.

[0035] Small axial strokes correspond to a low flow rate V, and larger strokes increase this accordingly.

[0036] To control the axial stroke length, the amplitude of the current pulses in the current profile applied to the respective coil 2', 2" is primarily varied. The stroke frequency f is kept constant for a certain range of the delivery volume flow V.

[0037] To control the flow rate V up to, for example, 7 [l / min], three operating frequencies are defined: a low, a medium, and a high stroke frequency f. These stroke frequencies f are optimally selected with regard to "NVH" ("noise, vibration, harshness") and can differ depending on the application area of ​​the fluid pump 1.

[0038] Low flow rates V are achieved at low stroke frequencies f and by varying the current values ​​i1, i2, as well as the current pulse duration (time interval) t1, t2 of the current profile. This control variant is in Fig. Figure 8a shows that higher flow rates V are controlled according to the same principle, but at medium or high stroke frequencies and with higher and different current values ​​i1, i2, as shown in Fig. 8b shown. Fig. 8a and Fig. In graph 8b, the x-axis represents time t and the y-axis represents current I.

[0039] The advantage of controlling the flow rate V by varying the stroke is that only operating frequencies with optimal NVH characteristics can be selected. The necessary current profiles for control by varying the stroke are stored in the control unit.

[0040] A mechanical malfunction of the fluid pump 1 can be detected via the stroke movement of the pump piston 3 by checking whether the pump piston 3 can perform a full stroke, or whether the pump piston 3 is stuck, for example, and can no longer move axially, thus resulting in no pumping action.

[0041] A complete stroke of the pump piston 3 can be detected either by the increase in the effective current or by the current ripple in the steady state.

[0042] If the pump piston 3 completes a full stroke, then the effective current rise in the coil 2', 2" over time is slower than if the pump piston 3 does not move. This difference is in the Fig. 9 shown. Fig. Figure 9 plots time t on the x-axis and current I on the y-axis. The solid line represents the current over time t with no stroke of pump piston 3. The dashed line represents the current over time t with a full stroke of pump piston 3. The control unit can evaluate this current increase (gradient calculation) and compare its duration with stored values, namely target values ​​for the current increase at no stroke, half a stroke, and a full stroke. A compensation factor accounts for the change in current increase as a function of temperature.

[0043] Another way to detect the stroke of the pump piston 3 is to evaluate the current ripple in the steady state. The current ripple results from the PWM control of the coils 2', 2". In addition to the effective current, the current ripple of each coil 2', 2" is also determined via the electronic control. The height of the current ripple represents the position of the pump piston 3 relative to each coil 2', 2". If the pump piston 3 is positioned on one side (first coil 2'), i.e., the air gap is 0 mm, then the current ripple of the first coil 2' is greater than when the pump piston 3 is entirely on the side of the second coil 2" (air gap is at its maximum relative to the first coil 2'). This is in Fig. 10 shown. Fig. In Figure 10, time t is plotted on the x-axis and current I on the y-axis. The solid line describes the current over time t when the pump piston 3 is fully extended. The dashed line describes the current over time t when the pump piston 3 is not extended.

[0044] In this way, a mechanical malfunction of the pump piston 3 can be detected by measuring the current ripple of both coils 2', 2". Furthermore, incomplete stroke movements can also be detected.

[0045] If a malfunction of the fluid pump 1 is diagnosed as a result of a jammed pump piston 3, a current profile with high pulsating current peaks can be imprinted after a sufficient cooling phase. The high pulsating armature forces implied by overexcitation of the magnetic circuit promote the release of the pump piston 3.

[0046] While the flow rate pulsations of rotary positive displacement pumps depend primarily on their geometric dimensions (number of teeth or number of displacement chambers per revolution of the pump drive shaft), flow rate pulsations can be modulated almost arbitrarily within the limits defined by the power output stage by appropriately controlling the two coils 2' and 2". For example, the fluid pump 1 can be operated with a time-varying control frequency f while maintaining a constant flow rate V over time. This allows flow rate pulsations to be modulated or influenced within given physical limits.

[0047] Furthermore, different flow rates V can be achieved at a constant stroke frequency f, but with incomplete stroke movements. The geometric displacement volume per stroke is thus correspondingly smaller, and a reduced flow rate V can be achieved at a constant stroke frequency f. This "floating" reversal before reaching the end stops requires a correspondingly dynamic current profile for controlling the coils 2', 2". Individual, incomplete stroke movements can be actively used in the fluid pump control, for example, to actively smooth flow rate pulsations.

[0048] By measuring the voltage drop across one or both coils 2', 2" the fluid temperature currently prevailing in the area of ​​the fluid pump 1 can be determined.

[0049] For this purpose, during the measurement the coil 2', 2" is supplied with a constant current for a short period of time and the voltage drop caused by the temperature-dependent coil resistance is determined. Through suitable design measures, the fluid can flow indirectly or directly around the coil 2', 2" . A redundant determination of the fluid temperature is possible by alternately measuring the voltage drop across both coils 2', 2" . The temperature measurement is preferably performed with the fluid pump 1 inactive.

[0050] Further information, which indirectly allows conclusions to be drawn about the fluid temperature, can be generated by current measurement (peak and / or RMS ("root mean square") value) at defined flow rates V.

[0051] A cooling and / or lubricant sump heater can be implemented by energizing one coil 2', 2", or by alternately energizing both coils 2', 2",. It is advantageous to perform individual pump strokes between the energizing phases to circulate the cooling and / or lubricant. In particular, this improves the low-temperature start-up behavior of the fluid pump 1, which is relevant for its use as a preconditioning pump. Since the fluid pump 1 is located largely within the cooling and / or lubricant sump, the majority of the electrical power loss is dissipated by the cooling and / or lubricant located both inside and outside the fluid pump 1.

[0052] In Fig. Figure 11 shows an exemplary flow diagram of the process 100 according to the invention.

[0053] Procedure 100 begins with a query block 101. Query block 101 checks whether active cooling and / or lubrication is required by the vehicle. If query block 101 is answered with "no" (-), the dual-coil piston pump does not need to be controlled for operation (block 200). If query block 101 is answered with "yes" (+), the dual-coil piston pump is controlled or set to an active pump operating mode (block 300).

[0054] For optimal operation, several predefined function blocks 400, 500, 600, 700, 800, 900 are subsequently executed, namely - a function block “Determination of the function-optimal current profile” 400 - a function block “Determination of fluid sump temperature” 500 - a functional block “coil heating function” 600 - a functional block “Diagnostics” 700 - a functional block “Releasing a jammed pump piston” 800 and - a function block “further application-specific function blocks” 900.

[0055] In the Fig. 12 to Fig. The individual function blocks 400, 500, 600, 700, 800, and 900 are shown in detail in section 16.

[0056] Fig. Figure 12 shows the function block "Determination of the Functionally Optimal Current Profile" 400 in detail. Within this function block 400, three query blocks 401, 402, and 403 are executed sequentially. Query block 401 checks whether the "Performance" mode is active. Query block 402 checks whether the "Efficiency" mode is active. Query block 403 checks whether the "NVH" mode is active. If each of these query blocks 401, 402, and 403 is answered with "no" (-), function block 414 "Look Up Table / Limp Home Mode" is executed. If query block 401 is answered with "yes" (+), function block 411 "Look Up Table / Performance Mode" is executed. If query block 402 is answered with "yes," function block 412 "Look Up Table / Efficiency Mode" is executed. If query block 403 is answered with "yes", function block 413 "Look Up Table / NVH Mode" is executed.

[0057] Fig. Figure 13 shows the functional block "Determination of Fluid Sump Temperature" 500 in detail. Within this functional block 500, three functional blocks 501, 502, and 503 run sequentially. In functional block 501, a resistance is determined by measuring the current at the first coil. In functional block 502, a resistance is determined by measuring the current at the second coil. In functional block 503, the average fluid temperature T is calculated. act, calc In a subsequent query block 504, it is checked whether "T act, calc ≤ T min , operation”, where T min , operation corresponds to a defined minimum operating temperature of the fluid. If this query block 504 is answered with "no" (-), then the function block "Diagnostics" 700 will subsequently be executed according to Fig. 15. If this query block is answered with "yes" (+), the function block "coil heating function" 600 is executed according to Fig. 14.

[0058] Fig. Figure 14 shows the "Coil Heating Function" function block 600 in detail. Within this function block, three function blocks 601, 602, and 700 run sequentially. In the "Coil Profile Coil Heating Function" function block 601, the fluid is heated to the specified temperature. min , operation Temperature is determined using an optimized current profile, which is selected from a look-up table depending on the current temperature and operating conditions. The fluid sump temperature is determined in function block 602, "Determination of Fluid Sump Temperature". Function block 700 is performed according to... Fig. 15.

[0059] Fig. Figure 15 shows the "Diagnosis" function block 700 in detail. Within this function block 700, four function blocks 500, 701, 702, and 703 run sequentially. The first function block, 500, has already been described using... Fig. 13 explained. In functional block 701, an induced current i is measured. A, indat the first coil. In functional block 702, an induced current i is measured. A, ind at the second coil. In functional block 703, the average induced current i is calculated. ind, clac In a subsequent query block 704, it is checked whether "i ind, calc ≤ i ind, soll “, where i ind, soll corresponds to a defined induced current. If this query block 704 is answered with "no" (-), then the "diagnosis OK" 705 is confirmed. If this query block is answered with "yes" (+), then the function block "Releasing a jammed pump piston" 800 is executed according to Fig. 16.

[0060] Fig. Figure 16 shows the functional block "Releasing a jammed pump piston" 800 in detail. Within this functional block 800, five functional blocks 500, 801, 802, 803, and 500 run sequentially. In the initial functional block 500 of this sequence, the fluid sump temperature is determined according to the flow diagram in [reference missing]. Fig. 13. In functional block 801, the maximum permissible RMS current i is calculated. max In functional block 802, the current profile, including current peaks, is determined. In functional block 803, the first coil and the second coil are alternately energized with the maximum permissible RMS current i. max Function block 803 can be repeated up to three times. Afterwards, a final function block 500 is executed, and the fluid sump temperature is determined according to the flowchart in [reference to flowchart]. Fig. 13. In the following query block 804, it is checked whether “T ac t, calc ≤ T min , operation If this query block 804 is answered with "no" (-), then function block 700 is executed, as already described in... Fig.As described in section 15. If this query block is answered with "yes" (+), function block 801 starts again, followed by function blocks 802, 803 and query block 804, which checks whether "T ac t, calc ≤ T min , operation “and this continues until query block 804 is answered with “no” (-). Reference symbol list 1 fluid pump 2' First coil 2" Second coil 3 pump pistons 4 cylinders 5' First exhaust valve 5" Second exhaust valve 6' First inlet valve 6" Second Inlet Valve 7 Central longitudinal axis of the pump piston 18' First freewheeling diode 18" Second freewheeling diode 19 2-pole electrical connection 20 3-pole electrical connection V Flow rate f stroke rate t time t1 First time interval t2 Second time interval t3 Third time interval Δt_ time difference i, I current i1 First current i2 Second stream i3 Third Power T act, calc Calculated mean fluid temperature T min , operation Defined minimum operating temperature of the fluid i ind, calc Calculated actual current i ind, soll Induced target current i A , i nd Induced current i max Maximum permissible RMS current 100 methods for controlling an electromagnetically actuated fluid pump 101, 401, 402, 403, 504, 704, 804 query block 200, 300, 400, 411, 412, 413, 414, 500, 501, 502, 503, 600, 601, 602, 700, 701, 702, 703, 705, 800, 801, 802, 803, 900 Function block + “yes” "no"

Claims

[1] Method (100) for controlling an electromagnetically actuated fluid pump (1), wherein the fluid pump (1) has an axially movable pump piston (3) for displacing and conveying a coolant and / or lubricant, wherein a coil (2', 2") is arranged in the region of each of the two axial ends of the pump piston (3), which together with the pump piston (3) form a lifting magnet and thus the pump piston (3) can be electromagnetically actuated on both sides, wherein a delivery volume flow (V) of the fluid pump (1) is controlled by varying the stroke of the pump piston (3) by varying the amplitude of current pulses of a current profile applied to the respective coil (2', 2"), wherein the necessary current profiles are stored in a control unit and wherein a stroke frequency (f) is kept constant over a defined range of the delivery volume flow (V), wherein three operating frequencies are defined, namely a low,a medium and a high stroke frequency (f), wherein low delivery volume flows (V) are set at the low stroke frequency (f) by varying current values ​​(i1, i2) and a current pulse duration (t1, t2) of the current profile, and higher delivery volume flows (V) are controlled according to the same principle, but at the medium or high stroke frequency and with higher and different current values ​​(i1, i2).

Images