Method for controlling a pump unit

Abstract

The invention relates to a method for controlling a pump unit, in particular for actuating and / or supplying at least one component of a drive train of a motor vehicle by means of at least one setpoint volume flow (Q Soll ), wherein a pump (105) having at least one duct (120) for at least one setpoint volume flow (Q Soll ) is driven in a rotational manner by an electric motor (110) and is provided with a rotational speed controller (125) for setting the at least one setpoint volume flow (Q Soll ) by means of rotational speed control of the pump (105). In order to achieve the determination of the setpoint rotational speed (n set ) in a stable manner and with a minimum of computing effort, a determination of the setpoint rotational speed (n set ) based on an initial rotational speed is provided for the purpose of the rotational speed control during operation of the pump (105).

Description

TECHNICAL FIELD

[0001] The invention relates to a pump unit, in particular for actuating and / or supplying at least one component of a drive train of a motor vehicle by means of at least one setpoint volume flow, and to a method for controlling the pump unit, wherein a pump having at least one duct for at least one setpoint volume flow is driven in rotation by an electric motor and is provided with a rotational speed controller for setting the at least one setpoint volume flow by means of rotational speed control of the pump. BACKGROUND

[0002] A double-flow pump unit is known from DE 10 2011 100 845 A1, in which a first pump mainly cools a component of the drive train and a second pump actuates a double clutch. Both pumps can be connected to an accumulator by means of a hydraulic valve. Both pumps are controlled by means of rotational speed control of an electric motor driving both pumps, wherein one of the two pumps is connected to the electric motor in a detachable manner by means of a clutch. SUMMARY

[0003] It is an object of the invention to further develop an electrically arranged pump unit and to further develop a method for controlling the pump unit. In particular, it is an object of the invention to propose a pump unit and a method for controlling the pump unit which is stable and can be controlled with a minimum of computing effort.

[0004] The proposed pump unit actuates and / or supplies at least one component of a drive train of a motor vehicle, in particular. For example, a clutch, a decoupling clutch between an internal combustion engine and an electric machine of a hybrid drive train, for example, at least one friction clutch between an internal combustion engine and a transmission, a parking lock, one or both axially movable discs of a transmission of a belt-type continuously variable transmission, etc. can be actuated by the pump unit by means of a first pump flow of a supply high-pressure duct. In addition, cooling and lubrication of the clutch, the disc pack of the belt, etc. can be provided, for example, by means of a second pump flow of a supply low-pressure duct. By setting an appropriate speed for a given displacement and efficiency, the pump unit sets a certain volume flow at the appropriate duct, the high-pressure duct and / or the low-pressure duct. At least one single-flow pump or double-flow pump of the pump unit is driven in rotation by an electric motor. The electric motor is controlled by means of a control unit having a rotational speed controller which provides speed control of the electric motor and thus of the pump to set the speed for providing the at least one volume flow.

[0005] The specific volume flow, such as the setpoint volume flow, is set based on a setpoint rotational speed according to the displacement of the pump and the efficiency of the pump. In this case, an initial rotational speed is output by the rotational speed controller, and a setpoint rotational speed is determined using a fixed-point iteration of the initial rotational speed during operation of the pump.

[0006] The pump unit can have a single-flow pump or a double-flow pump. In the case of a double-flow pump, the pump unit can have a first high-pressure duct for actuating the component and a second low-pressure duct for supplying the component. According to a special embodiment, the high-pressure duct and the low-pressure duct of the double-flow pump can be connected to one another by means of a pressure-limiting valve.

[0007] The proposed method serves to control the aforementioned pump unit having specific properties. Here, the initial rotational speed of the pump is determined, for example, estimated, using the specific efficiency of the pump in relation to the system and the setpoint volume flow required to complete the task of the pump unit, and the electric motor is operated at this initial rotational speed. The setpoint rotational speed resulting from the displacement of the pump and the volume efficiency of the pump cannot be directly set for the required, i.e., setpoint volume flow, which can be a function of the speed of the pump, the temperature of the pump fluid, etc. In order to determine and set the setpoint rotational speed of the pump, a correction value is determined based on the set initial rotational speed and a predetermined number of iteration steps and the setpoint volume flow having a known displacement, with which the setpoint rotational speed is determined and set from the initial rotational speed. The setpoint rotational speed n set is derived from equation (1)

[0008] n set = Q Soll / (V d η V ) (1)

[0009] where Q Soll is the setpoint volume flow and V d is the displacement of the pump and η V is the volume efficiency. In this case, each iteration step results in a decreasing correction value, which increases the setpoint rotational speed with increasing number. The efficiency η V may be read and interpolated, for example, from a table stored in the control unit. Alternatively, the known maximum efficiency of the pump or an efficiency equal to 1 can be used as a good approximation.

[0010] As the rotational speed of the electric motor approaches the desired setpoint rotational speed with the number of iteration steps in the case of alternating over- and under-compensation of the correction values, for safety reasons, it can be advantageous to limit the setpoint rotational speed to an odd number at least during the adjustment process during the point iteration, so that at the expense of economic operation, a functionally reliable setpoint rotational speed is always determined and set. For example, for most applications, the point iteration can be limited to one iteration with sufficient accuracy of the setpoint rotational speed, i.e. it is sufficient to determine only one iteration step with a single correction value and to correct the initial rotational speed with this correction value in order to obtain a sufficiently accurate setpoint rotational speed.

[0011] It is also advantageous to apply a safety value to the setpoint rotational speed determined according to at least one iteration step. For example, a safety factor can be added to the determined setpoint rotational speed, or a safety sum can be added. The safety value can be constant or adapted to the operating conditions; for example operating age, temperature, setpoint rotational speed and / or similar parameters.

[0012] In the case of a single-flow pump, it is sufficient if the setpoint rotational speed calculates the setpoint volume flow of a single conduit. In the case of a double-flow pump with two conduits, in particular with a high-pressure conduit and a separate low-pressure conduit, it is advantageous to operate the double-flow pump using the proposed point iteration to determine the setpoint rotational speed for each conduit and the maximum setpoint rotational speed required for one of the two setpoint volume flows. Here, alternatively or additionally, the conduit which is prioritized with regard to its function, for example the high-pressure conduit when the components are actuated or the low-pressure conduit in the case of critical temperatures or lubrication, can be preferred, and the setpoint rotational speed required for this conduit can be set.

[0013] In a double-flow pump with two conduits, i.e. with a high-pressure conduit and a low-pressure conduit connected to the high-pressure conduit by means of a hydraulic coupling, for example a pressure relief valve, after each iteration step, the setpoint rotational speed for each conduit can be determined. From these two setpoint rotational speeds, the maximum setpoint rotational speed required for one of the two setpoint volume flows can be determined. The setpoint rotational speed for the currently most important function can be prioritized. After or before the prioritization, the selected setpoint rotational speed can be iteratively corrected according to the size of the volume exchanged via the hydraulic coupling, for example the volume loss via the pressure relief valve. The size of the volume exchange can be determined from the current efficiency of the pump at the current speed of the low-pressure conduit and the current efficiency at the current speed of the high-pressure conduit. BRIEF DESCRIPTION OF DRAWINGS

[0014] REFERENCE Figures 1 to 6The exemplary embodiments shown in the middle illustrate the application in more detail. In the drawings:

[0015] Figure 1 a schematic hydraulic plan view of a single-flow pump unit is shown,

[0016] Figure 2 a method for operating a pump unit using fixed-point iteration is shown, Figure 1

[0017] Figure 3 a schematic hydraulic plan view of a double-flow pump unit is shown,

[0018] Figure 4 a method for operating a pump unit using fixed-point iteration is shown, Figure 3

[0019] Figure 5 a schematic hydraulic plan view of a double-flow pump unit with hydraulic coupling of the conduits is shown,

[0020] Figure 6 a method for operating a pump unit using fixed-point iteration is shown. Figure 5 DETAILED DESCRIPTION

[0021] Figure 1 a schematic simplified representation of a pump unit 100 with a single-flow pump 105 driven in rotation by an electric motor 110 is shown, the single-flow pump drawing in hydraulic fluid from a sump 115 and feeding a setpoint volumetric flow rate Q Soll into a conduit 120, for example for actuating a hydraulically operated clutch, park lock or brake.

[0022] the setpoint volumetric flow rate Q Soll is adjusted by a rotational speed controller 125 according to a setpoint rotational speed n set of the pump 105 and a current actual rotational speed n act .

[0023] Figure 1 the setpoint rotational speed n set of the pump 105 is determined using the routine 130 shown in Figure 2 In block 135, the pump 105 is operated at an initial rotational speed n I formed from the desired setpoint volumetric flow rate Q Soll of the pump 105 and the displacement V d . In a fixed-point iteration 140, while the pump 105 is running, in the course of one or more iteration steps, the current speed n act ​​​Assigned, for example by means of the velocity-dependent efficiency η in box 145. V And, if necessary, other variables, such as the temperature of the hydraulic fluid, are interpolated from a table of characteristic graphs to allocate the values. Then, in box 150, the allocation is based on the efficiency η. V The setpoint volumetric flow rate Q to be calibrated Soll and displacement V d The quotient is used to determine the rotational speed n at the setpoint. set To proceed with further iteration step 155, a branch is established for box 145 if necessary. It has been shown that performing an odd number of iterations, particularly a single iteration as illustrated, is advantageous. At the end of fixed-point iteration 140, the rotation speed n of the setpoint in box 160 can be... set Apply a safety value, as shown here, multiplied by a safety factor F greater than one.

[0024] Figure 3 A schematic simplified representation of a pump unit 200 with a dual-flow pump 205, driven in a rotary manner by an electric motor 210, is shown. The dual-flow pump draws hydraulic fluid from a reservoir 215 and delivers a setpoint volumetric flow rate Q. Cool Q Sys It is supplied to two pipes, namely low-pressure pipe 220 and high-pressure pipe 221; for example, to cool or lubricate hydraulic components and to actuate hydraulically actuated clutches, brakes or parking locks.

[0025] Setpoint volumetric flow rate Q Cool Q Sys The rotational speed controller 225 determines the rotational speed n of the pump 205 based on the setpoint. set and the current actual rotational speed n act To adjust. Here, the setpoint volumetric flow rate Q Cool Q Sys The ratios relative to each other are specified by the displacement and efficiency of the dual-flow pump 205. Advantageously, the displacements for the two pipes are similar.

[0026] With Figure 1 The setpoint rotational speed n of the pump unit 100 in the middle set Corresponding to the determination, for the setting Figure 3 The setpoint volumetric flow rate Q of pump 205 Cool Q Sys The set point rotation speed n set,LP n set,HP The determination in Figure 4 The routines shown in 230 are performed independently of each other.

[0027] In box 237, pump 205 operates at an initial rotational speed n IOperation, the initial rotation speed is the same as the initial rotation speed n of frames 235 and 236. I,LP n I,HP Correspondingly, these initial rotational speeds are based on the desired setpoint volumetric flow rate Q of pump 205. Cool Q Sys With displacement V d,LP V d,HP The quotient is formed. In fixed-point iteration 240, when pump 205 is running, during the operation of one or more iteration steps 255, the current speed n of pump 205 is... act Assigned, for example, by means of a velocity-dependent efficiency η V,LP η V,HP And other variables, such as the temperature of the hydraulic fluid, are assigned by interpolation in the corresponding boxes 245 and 246 of the characteristic diagram, if necessary. Then, in boxes 250 and 251, the efficiency η is used for allocation. V,LP η V,HP Corrected setpoint volumetric flow rate Q Cool Q Sys and displacement V d,LP V d,HP The quotient is used to determine the rotational speed n at the setpoint. set,LP n set,HP .

[0028] In order to use the setpoint volumetric flow rate Q Cool To ensure stable and safe operation of both lubrication and cooling of components, and to utilize the setpoint volumetric flow rate Q Sys To actuate the components, rotate the setpoints of frames 250 and 251 at a speed n. set,LP n set,HP The two points are compared in box 265, and the rotation speed n is determined based on the two set points. set,LP n set,HP The highest value among them determines the rotational speed n at the setpoint. set,Basis The setpoint rotational speed n set,Basis Used for calibrating pump 205.

[0029] To proceed with further iteration step 255, a branch is established for box 245 after box 265, if necessary. It has been shown that performing an odd number of iteration steps, and in particular, performing only one iteration step as illustrated, is advantageous.

[0030] At the end of fixed-point iteration 240, the rotational speed n of the setpoint can be set in box 260. set,Basis Apply a safety value, as shown here, multiplied by a safety factor F greater than one.

[0031] Figure 5A simplified schematic diagram illustrates a pump unit 300 with a dual-flow pump 305, which is related to... Figure 3 Similar to pump unit 200, the dual-flow pump is driven in a rotary manner by electric motor 310. This dual-flow pump draws hydraulic fluid from reservoir 315 and delivers the setpoint volumetric flow rate Q. Cool Q Sys It is supplied to two pipes, namely low-pressure pipe 320 and high-pressure pipe 321; for example, to cool or lubricate hydraulic components and to actuate hydraulically actuated clutches, brakes or parking locks.

[0032] Setpoint volumetric flow rate Q Cool Q Sys The rotational speed controller 325 determines the rotational speed n of the pump 305 based on the setpoint. set and the current actual rotational speed n act To adjust. Here, the setpoint volumetric flow rate Q Cool Q Sys The ratios relative to each other are specified by the displacement and efficiency of the dual-flow pump 305. Advantageously, the displacements for both pipes are similar.

[0033] Compared to pump unit 200, pump unit 300 is provided with a hydraulic connection 370 between high-pressure pipeline 321 and low-pressure pipeline 320, so that the setpoint volumetric flow rate Q Cool and Q Sys Designed to be interconnected. Hydraulic connection 370 is formed by pressure relief valve 375, which is controlled by the system pressure of high-pressure line 321, and, if necessary, transfers overpressure generated in high-pressure line 321 to low-pressure line 320, thereby increasing the setpoint volumetric flow rate Q of the low-pressure line. Cool It can be enlarged.

[0034] Figure 6 Example 330 shown illustrates a rotational speed n based on a setpoint. set,Basis For targeting Figure 5 The setpoint volumetric flow rate Q of the pump unit 300 Cool Q Sys To perform control. Here, routine 330 and Figure 4 The corresponding routine 230 continues until the setpoint rotational speed n is determined in box 265. set,Basis The setpoint rotational speed n, determined in block 365 of routine 330 or in another determination method. set,Basis The effect of hydraulic connection 370 in the additional fixed-point iteration 380. (Refer to...) Figure 4 The procedure of routine 230 is used to determine the rotational speed n at the setpoint. set,Basis .

[0035] The influence of hydraulic connection 370 is corrected, and the efficiency η is determined again according to Figures 345 and 346. v,HP η v,LP For example, by means of interpolation based on a previously determined setpoint rotational speed n set,Basis To determine efficiency. In box 385, the corrected setpoint rotational speed n set,erw Based on the rotational speed n at the set point set,Basis Considering the given efficiency η v,HP η v,LP The setpoint rotational speed for calibration is determined by the quotient of the following numerator and denominator: the numerator is the setpoint volumetric flow rate Q of high-pressure pipeline 321. Sys In addition to the efficiency η of the pump flow rate for low-pressure pipeline 320 v,LP Displacement V of the pump for low-pressure pipeline 320 d,LP and the current setpoint rotation speed n set,Basis The product of, and the denominator is efficiency η. v,HP η v,LP Multiply by the displacement V of the pump pipe of high-pressure pipe 321 respectively d,HP The displacement V of the pump pipeline of low-pressure pipeline 320 d,LP The sum of the products of .

[0036] If one or more iteration steps are required, especially an odd number of iteration steps, then at the beginning of the fixed-point iteration, the rotation speed n of the setpoint for the corresponding currently determined extension is set. set,erw Create a branch.

[0037] At the end of fixed-point iteration 380, the rotational speed n of the setpoint can be set in box 360. set,erw Apply a safety value, as shown here, multiplied by a safety factor F greater than one.

[0038] Because of the fixed-point iteration 380 shown, the complex algorithmic considerations of multidimensional tables for depicting the hydraulic effects of hydraulic connection 370 and the hydraulic effects of hydraulic connection can be omitted.

[0039] Explanation of reference numerals in the attached figures

[0040] [2]100 pump unit 105 pump 110 electric motor 115 tank 120 conduit 125 rotational speed controller 130 routine 135 block 140 fixed-point iteration 145 block 150 block 155 iteration step 160 block 200 pump unit 205 pump 210 electric motor 215 tank 220 low-pressure conduit 221 high-pressure conduit 225 rotational speed controller 230 routine 235 block 236 block 237 block 240 fixed-point iteration 245 block 246 block 250 block 251 block 255 iteration step 260 block 265 block 300 pump unit 305 pump 310 electric motor 315 tank 320 low-pressure conduit 321 high-pressure conduit 325 rotational speed controller 330 routine 345 block 346 block 360 block 365 block 370 hydraulic coupling 375 pressure-limiting valve 380 fixed-point iteration 385 block 390 iteration step F safety factor n act current actual rotational speed n I initial rotational speed n ,IHP initial rotational speed n I,LP initial rotational speed n set,HP setpoint rotational speed n set,LP setpoint rotational speed n set setpoint rotational speed n set,Basis setpoint rotational speed n set,erw setpoint rotational speed Q Cool setpoint volumetric flow rate Q Soll setpoint volumetric flow rate Q Sys setpoint volumetric flow rate V d displacement V d,HP displacement V d,LP displacement η V efficiency η V,HP efficiency η V,LP efficiency.

Claims

1. A method for controlling a pump unit (100, 200, 300), said pump unit being specifically designed for controlling a volumetric flow rate (Q) at at least one setpoint. Cool Q Soll Q Sys Actuates at least one component of the transmission system of a motor vehicle and / or supplies power to said at least one component, having a volumetric flow rate (Q) for said at least one setpoint. Cool Q Soll Q Sys At least one pipe (120) of the pump (105, 205, 305) is driven in a rotary manner by an electric motor (110, 210, 310), and is provided with a rotation speed controller (125, 225, 325) for setting the at least one setpoint volumetric flow rate (Q) by means of the rotation speed control of the pump (105, 205, 305). Cool Q Soll Q Sys ), characterized in that, During the operation of the pumps (105, 205, 305), a value based on the initial rotational speed (n) is provided. I The fixed-point iteration (140, 240, 380) is applied to the rotational speed (n) of the setpoint. set n set,Basis n set,erw The determination is made for the purpose of said rotational speed control; Based on the maximum possible efficiency of the pump (105, 205, 305) or an efficiency equal to 1 (η) V η V,HP η V,LP ) and the required setpoint volumetric flow rate (Q) Cool Q Soll Q Sys To determine the initial rotational speed (n) of the pump (105, 205, 305) I ), and the setpoint rotational speed (n) of the pumps (105, 205, 305) set n set,Basis n set,erw Based on the initial rotational speed (n) I The number of iteration steps (155, 255, 390) and a specific number of iteration steps are determined, wherein the iteration steps are related to the efficiency (η) of the pump (105, 205, 305). V η V,HP η V,LP ) and the setpoint volumetric flow rate (Q) Cool Q Soll Q Sys The efficiency is associated with the correction value of the initial rotational speed (n). I (This is currently determined.) 2. The method according to claim 1, characterized in that, The pump (205, 305) has a high-pressure conduit (221, 321) for actuating the components and a low-pressure conduit (220, 320) for supplying the components.

3. The method according to claim 2, characterized in that, The high-pressure pipe (321) and the low-pressure pipe (320) are hydraulically connected to each other.

4. The method according to claim 2 or 3, characterized in that, The low-pressure conduits (220, 320) are configured for lubricating and / or cooling at least one component, and the high-pressure conduits (221, 321) are configured for actuating the clutch, parking brake, and / or the disc assembly of a belt-driven continuously variable transmission.

5. The method according to claim 1, characterized in that, The number of iteration steps (155, 255, 390) is odd.

6. The method according to claim 5, characterized in that, The safety value is applied to the setpoint rotation speed (n) determined according to at least one of the iterative steps (155, 255, 390). set n set,Basis n set,erw ).

7. The method according to claim 6, characterized in that, In the case of a dual-flow pump (205) with two pipes, after each iteration step (155) for each pipe, the setpoint rotation speed (n) set,HP n set,LP The volumetric flow rate (Q) of the pump (205) at the two set points is determined. Cool Q Sys The maximum setpoint rotation speed (n) required for the setpoint volumetric flow rate in ) set,Basis (The following operations are performed.) 8. The method according to claim 7, characterized in that, The pipeline consists of a high-pressure pipeline (221) and a low-pressure pipeline (220) separate from the high-pressure pipeline.

9. The method according to claim 8, characterized in that, In the case of a dual-flow pump (305) having two pipes, namely a low-pressure pipe (320) connected to the high-pressure pipe by means of a pressure relief valve (375), the setpoint rotational speed (n) of each pipe set,HP n set,LP The maximum setpoint rotation speed (n) required to determine one of the two setpoint volumetric flow rates is determined after each iteration step. set,Basis ), and the rotational speed of the set point (n) set,Basis Iterative correction is performed using volume exchange via the hydraulic connection (370) between the high-pressure pipeline and the low-pressure pipeline.

10. The method according to claim 9, characterized in that, According to the current set point rotation speed (n) of the pump (305) in the low-pressure pipeline (320) set，Basis Current efficiency (η) under ) V,LP ) and the current efficiency (η) at the current setpoint rotational speed of the high-pressure pipeline (321). V,HP The size of the volume exchange is determined by this method.

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