WO2021110202A1

WO2021110202A1 - Double-flow pump unit, and method for controlling same

Info

Publication number: WO2021110202A1
Application number: PCT/DE2020/100956
Authority: WO
Inventors: Yunfan Wei; Marco Grethel; Carsten Mayer
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2019-12-03
Filing date: 2020-11-06
Publication date: 2021-06-10
Also published as: CN115151730A; US20230003213A1; DE102019132770B3

Abstract

The invention relates to a pump unit (100) and to a method for controlling same, in particular for actuating and/or providing a supply to at least one component of a drive train of a motor vehicle by means of at least one setpoint volumetric flow (Q_soll), wherein a pump (105) with at least one duct (120) for the at least one setpoint volumetric flow (Q_soll) is rotationally driven by an electric motor (110), and a rotational speed controller (125) is provided for setting the at least one setpoint volumetric flow (Q_soll) by means of rotational speed control of the pump (105). In order to implement the determination of a setpoint rotational speed (n_set) in a robust manner and with minimised computing effort, a determination of the setpoint rotational speed (n_set) on the basis of a fixed-point iteration of an initial rotational speed is provided during the operation of the pump (105) for the purposes of the rotational speed control.

Description

Two-flow pump unit and method of controlling it

The invention relates to a pump unit and a method for controlling it 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 target volume flow, where a pump with at least one channel for the at least one target volume flow is rotationally driven by an electric motor and a speed controller for setting the at least one volume flow is provided by means of a speed control of the pump.

From the document DE 102011 100845 A1, a double-flow pump unit is known, wherein a first pump is mainly used to cool components of a drive train and a second pump is used to operate a double clutch. Both pumps can be connected to a pressure accumulator by means of a hydraulic valve. Both pumps are controlled by means of a speed control of an electric motor driving them, one of the pumps being releasably connected to the electric motor by means of a coupling.

The object of the invention is to develop an electrically arranged pump unit and to develop the method for controlling it. In particular, the object of the invention is to propose a pump unit that is robust and controllable with minimal computing effort and a method for controlling it.

The object is achieved by the subjects of claims 1 and 5. The claims dependent on claims 1 and 5, respectively, provide advantageous embodiments of the subjects of these claims 1. The proposed pump unit is used in particular to actuate and / or supply at least one component of a drive train of a motor vehicle. For example, a clutch, for example a separating clutch between an internal combustion engine and an electric machine of a hybrid drive train, at least one friction clutch between an internal combustion engine and a transmission, a parking lock, one or both axially displaceable Discs ben a variator of a continuously adjustable belt drive or the like are operated. In addition, cooling of a clutch, the pulley sets of the belt or the like and their lubrication can be provided, for example, by means of a second pump flow that supplies a low-pressure channel. By setting a corresponding speed for a given displacement volume and efficiency, the pump unit sets a volume flow to the corresponding high-pressure and / or low-pressure channel. The at least one single- or double-flow pump of the pump unit is rotationally driven by means of an electric motor. The electric motor is controlled to set a speed for providing the at least one volume flow by means of a control unit with a speed controller, which provides a speed control of the electric motor and there with the pump. The setting of a predetermined volume flow, such as the target volume flow, takes place on the basis of the target speed depending on the displacement volume of the pump and its efficiency. Here, an initial speed is output from the speed controller and the target speed is determined using a fixed point iteration of this initial speed during operation of the pump. The pump unit can here have a single-flow or double-flow pump. In the case of a double-flow pump, the pump unit can have a first high-pressure channel for actuating a component and a second low-pressure channel for supplying a component. According to a particular embodiment, the high pressure channel and the low pressure channel of a double-flow pump can be connected to one another by means of a pressure relief valve.

The proposed method is used to control the aforementioned pump unit with its named characteristics. In this case, given a system-related efficiency of the pump and a required set volume flow to fulfill the task of the pump unit, an initial speed of the pump is determined, for example estimated, and the electric motor is operated at this initial speed. The target speed resulting from the displacement volume of the pump and its volumetric efficiency, which can be a function of the speed of the pump, the temperature of the pump fluid and the like, for example, is not directly adjustable for the required, that is to say, set target volume flow. To determine and set the target speed of the pump, a correction value is determined based on the set initial speed and a specified number of iteration steps and the target volume flow with a known displacement volume, with which the target speed is determined and set from the initial speed. The target speed n _set results from equation (1) from nset ⁼ Qsoll / (Vd * v) (1) with the target volume flow Qsoii and the displacement volume Vd of the pump as well as the volumetric efficiency v. Here, with each iteration step, reduced correction values result, which the setpoint speed with increasing number improve. The efficiency v can, for example, be read out and interpolated from tables (loop tables) stored in the control unit. Alternatively, the maximum efficiency known for the pump or an efficiency equal to one can be used as a good approximation. Due to the speed of the electric motor approaching the desired target speed with the number of iteration steps alternating with over and under compensation of the correction values, it can be advantageous for safety reasons to limit the target speed to odd numbers at least during the adjustment process during the fixed point iteration, so that A functionally reliable target speed is always determined and set at the expense of economic operation. For most applications, for example, the fixed point iteration can be limited to one with sufficient accuracy of the setpoint speed, i.e. it is sufficient to only determine one iteration step with a single correction value and to correct the initial speed with this correction value to obtain a sufficiently accurate one Obtain target speed.

It can also be advantageous to apply a safety value to the target speed determined from the at least one iteration step. For example, a safety factor can be applied to the determined setpoint speed or a safety sum can be added. The safety value can be designed to be constant or adapted to the operating situation, for example operating age, temperature, setpoint speed and / or the like.

In the case of a single-flow pump, it is sufficient if the target speed calculates the target volume flow of the single channel. In the case of a double-flow pump with two channels, in particular one high-pressure channel and a low-pressure In the pressure channel, it is advantageous to determine the target speed for each by means of the proposed fixed point iteration and to operate the double-flow pump at the maximum target speed required for one of the two target volume flows. As an alternative or in addition, the channel prioritized with regard to its function, for example the floch pressure channel when a component is actuated or the low pressure channel when a critical temperature or lubrication occurs, can be preferred and its required setpoint speed can be set.

In a double-flow pump with two channels, namely a floch pressure channel and a low pressure channel connected to this by means of a hydraulic coupling, for example an overpressure valve, a target speed can be determined for each channel after each iteration step. From these two setpoint speeds, the maximum setpoint speed required for one of the two setpoint volume flows can be determined. The target speed for the currently most important function can be prioritized. Subsequently or before the prioritization, the selected target speed can be corrected iteratively with a quantity of a volume exchange via the hydraulic coupling, for example a volume loss via the pressure relief valve. This size of the volume exchange can be determined from the current efficiency of the pump at the current speed of the low pressure channel and the floch pressure channel.

The invention is explained in more detail with reference to the Ausführungsbei shown in Figures 1 to 6 games. These show:

1 shows a schematic Flydraulikplan for a single-flow pump unit, FIG. 2 shows a method for operating the pump unit of FIG. 1 using a fixed point iteration,

Figure 3 is a schematic Flydraulic plan for a double-flow pump unit, FIG. 4 shows a method for operating the pump unit of FIG. 3 using a fixed point iteration,

Figure 5 is a schematic Flydraulikplan for a double-flow pump unit with a hydraulic coupling of the channels,

FIG. 6 shows a method for operating the pump unit of FIG. 5 using a fixed point iteration.

Figure 1 shows a schematically simplified representation of the pump unit 100 with the single-flow pump 105 driven in rotation by the electric motor 110, which sucks hydraulic fluid from the sump 115 and introduces the target volume flow Qsoii into the channel 120, for example to actuate a hydraulically operated clutch, parking lock or brake .

The setpoint volume flow Qsoii is regulated by means of the speed controller 125 from the setpoint speed n _se t and the current actual speed n _ac t of the pump 105.

The target speed n _se t of the pump 105 in FIG. 1 is determined by means of the routine 130 shown in FIG. 2. In block 135, the pump 105 is operated at the initial speed m, which is derived from the quotient of the desired target volume flow Qsoii and the displacement volume Vd the pump 105 is formed. In the fixed point iteration 140, with the pump 105 running, the current speed nact of the pump 105, for example, is determined in one pass of one or more iteration steps from the table in block 145 with the characteristic field of the speed-dependent efficiencies v and possibly other variables such as the temperature of the hydraulic fluid and the like assigned by interpolation. The set speed nset is then determined in block 150 from the quotient of the set volume flow Qsoii and the displacement volume Vd corrected with the efficiency v. A branch is made to block 145 in order to carry out any further iteration steps 155. It has proved to be advantageous to carry out an odd number of iteration steps, in particular only one iteration step as shown. At the end of the fixed point iteration 140, _{a safety value can be applied to the setpoint speed n se} t in block 160, as shown here, it can be multiplied by the safety factor F greater than one.

FIG. 3 shows in a schematically simplified representation the pump unit 200 with the double-flow pump 205 driven in rotation by the electric motor 210, which sucks hydraulic fluid from the sump 215 and, for example, the target volume flows Qcooi, Qsys into the two channels, namely the low pressure channel 220 and the floch pressure channel 221 for cooling or lubrication of hydraulic compo nents and for actuating a hydraulically operated clutch, brake or parking lock initiates.

The setpoint volume flows Qcooi, Qs _ys are regulated by means of the speed controller 225 from the setpoint speed n _se t and the current actual speed n _ac t of the pump 205. Here, the ratio of the setpoint volume flows Qcooi, Qs _ys to one another is predetermined by the displacement volumes and the efficiency of the double-flow pump 205. Before geous enough, the displacement volumes for the two channels are designed similarly.

According to the determination of the target speed n _se t of the pump unit 100 of FIG. 1, the target speeds n _S et, LP, n _S et, HP are determined in order to set the target volume flows Qcooi, Qsys of the pump 205 of FIG. 3 in routine 230 of FIG shown separately from each other.

In block 237, the pump 205 is operated at the initial speed m speed, each of which corresponds to the initial speeds m, i_p, ni.Hp of blocks 235, 236, which from the The quotient of the desired target volume flows Qcooi, Qs _ys and the displacement volumes Vd.LP, Vd.Hp of the pump 205 is formed. In the fixed point iteration 240, with the pump 205 running, one or more iteration steps 255 from the respective blocks 245, 246 with the maps of the speed-dependent efficiencies V.LP, V, HP and possibly other variables such as the temperature of the hydraulic fluid and the like are assigned to the current speed n _ac t of the pump 205, for example by interpolation. The target speeds nset.LP, n _se t, HP are then calculated in blocks 250, 251 from the quotients of the target volume flows Qcooi, Qsys and the displacement volume Vd.LP, Vd.HP corrected with the efficiencies V.LP, V, HP certainly.

For the robust and safe implementation of both the lubrication / cooling of components by means of the set volume flow Qcooi and for the actuation of components by means of the set volume flow Qs _ys , the set speeds n _se t, LP, n _se tHP of blocks 250, 251 are set in block 265 compared with each other and the target speed n _se t, base from the highest of the two target speeds n _se t, LP, n _se t, H _{P is} determined. This setpoint speed n _se t, Basis is used to correct the pump 205.

In order to carry out further iteration steps 255, if necessary, a branch is made to block 245 after block 265. It has proven to be advantageous to carry out an odd number of iteration steps, in particular only one iteration step as shown.

At the end of the fixed point iteration 240, a _{safety value can be applied to the setpoint speed n se} t, base in block 260, as shown here, can be multiplied by the safety factor F greater than one.

FIG. 5 shows the pump unit 300, which is similar to the pump unit 200 of FIG Electric motor 310 rotary-driven pump 305, which sucks hydraulic fluid from sump 315 and feeds the target volume flows Qcooi, Qs _ys into the two channels, namely low-pressure channel 320 and high-pressure channel 321, for example for cooling or lubricating hydraulic components and for actuating a hydraulically operated clutch, Brake or parking lock initiates.

The setpoint volume flows Qcooi, Qs _ys are regulated by means of the speed controller 325 from the setpoint speed n _set and the current actual speed n _{act of} the pump 305. Here, the ratio of the setpoint volume flows Qcooi, Qs _ys to one another is predetermined by the displacement volumes and the efficiency of the double-flow pump 305. The displacement volumes for the two channels are advantageously designed to be similar.

In contrast to the pump unit 200, the hydraulic coupling 370 is provided in the pump unit 300 between the high-pressure channel 321 and the low-pressure channel 320, so that the setpoint volume flows Qcooi and Qs _ys are designed to be mutually dependent. The hydraulic coupling 370 is formed by the pressure relief valve 375, which is steered by the system pressure of the high pressure channel 321 and derives a resulting overpressure of the high pressure channel 321 into the low pressure channel 320, so that its target volume flow Qcooi increases if necessary. The routine 330 shown in FIG. 6 shows the control of the setpoint volume flows Qcooi, Qs _y s for the pump unit 300 of FIG. 5 on the basis of the setpoint speed n _set, Basis. In this case, routine 330 corresponds to routine 230 in FIG. 4 up to the determination of setpoint speed n _set, basis in block 265. The setpoint speed correspondingly determined in block 365 of routine 330 or in another determination method n _se t, Basis is adapted to the influence of the hydraulic coupling 370 in the additional fixed point iteration 380. Reference is made to the procedure of routine 230 in FIG. 4 for determining the setpoint rotational speed n _{se t, Basis.}

The influence of the hydraulic coupling 370 is corrected in that _{the efficiencies V} , HP, V, LP are again determined, for example by means of interpolation, from the blocks 345, 346 _{on the basis of the previously determined setpoint speed n se t, base.} In block 385, the corrected setpoint speed n _se t, eiw is determined from the setpoint speed n _se t, base, taking into account the determined efficiencies _V , HP, V, LP. The corrected target speed results from the quotient of the meter with the target volume flow Qsys of the floch pressure channel 321 plus the product of the efficiency, LP of the pump flow for the low pressure channel 320, the displacement volume Vd.Lp of the pump flow for the low pressure channel 320 and the current set speed n _se t, base and denominator with the sum of the products of the _{degrees of efficiency V} , HP, v.Lp each multiplied by the displacement volumes Vd, HP, Vd.Lp of the pump flows of the floch pressure channel 321 and the low pressure channel 320.

If one or more iteration steps 390, in particular a number of uneven iteration steps, are desired, a branch is made to the currently determined extended setpoint speed n _S et, eiwat the beginning of the fixed point iteration.

At the end of the fixed point iteration 380, in block 360 the setpoint speed n _S et, eiw with a safety value, can be multiplied by the safety factor F greater than one, as shown here.

The illustrated fixed point iteration 380 makes it possible to dispense with multidimensional tables depicting the hydraulic influence of the hydraulic coupling 370 and their complex algorithmic consideration. List of reference symbols

Pump unit

pump

Electric motor

swamp

channel

Speed controller

routine

block

Fixed point iteration

block

Iteration step

block

Pump unit

pump

Electric motor

swamp

Low pressure duct

High pressure channel

Speed controller

routine

block

Fixed point iteration

block

Iteration step

block 265 block

300 pump unit

305 pump

310 electric motor

315 swamp

320 low pressure duct

321 High pressure channel 325 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 riact current actual speed ni initial speed

IΊ, IHR initial speed rn.LP initial speed nset.HP target speed nset.LP target speed riset target speed riset, base target speed riset, exp target speed Qcool target volume flow Qsoll target volume flow

Qsys target volume flow

Vd displacement volume

Vd.HP displacement volume

Vd.LP displacement volume v efficiency

V, HP efficiency

V, LP efficiency

Claims

1. Pump unit (100, 200, 300) 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 set volume flow (Qcooi, Qsoii, Qs _ys ), a pump (105, 205, 305) having at least a channel (120) for the at least one target volume flow (Qcooi, Qsoii, Qs _ys ) is driven in rotation by an electric motor (110, 210, 310) and a speed controller (125, 225, 325) for setting the at least one target volume flow (Qcooi, Qsoii, Qs _ys) by means of a speed control of the pump (105, 205, 305 is provided), characterized in that for rotational speed control, a determination _set a target rotational speed (n _set n, et basis, n _S, erw) based on a fixed-point iteration (140, 240, 380) an initial speed (m) is provided during operation of the pump (105, 205, 305).

2. Pump unit (200, 300) according to claim 1, characterized in that the pump (205, 305) has a high pressure channel (221, 321) for actuating a component and a low pressure channel (220, 320) for supplying a component.

3. Pump unit (300) according to claim 2, characterized in that the high pressure channel (321) and the low pressure channel (320) are hydraulically coupled to one another, in particular by means of a pressure limiting valve (375) are connected to one another.

4. Pump unit (200, 300) according to claim 2 or 3, characterized in that the low-pressure channel (220, 320) for lubrication and / or cooling to at least one component and the high-pressure channel (221, 321) for actuating a clutch, a parking lock and / or a set of disks of a Varia sector of a continuously variable belt transmission are provided.

5. The method for controlling a pump unit (100, 200, 300) according to one of claims 1 to 4, characterized in that from a maximum possible or an efficiency (v, V, HP, V, LP) of the pump (105, 205 , 305) equal to one and a required target volume flow (Qcooi, Qsoii, Qs _ys ) an initial speed (m) of the pump (105, 205, 305) is determined and a target speed (n _set , n _set, Basis, n _S et, Erw) of the pump (105, 205, 305) based on the initial speed (m) and a predetermined number of iteration steps (155, 255, 390) with a combination of these with a correction value from an efficiency (v, V, HP, V, LP) of the pump (105, 205, 305) currently determined by means of the initial speed (m) and the setpoint volume flow (Qcooi, Qsoii, Qs _ys ) is determined.

6. The method according to claim 5, characterized in that the number of iteration steps (155, 255, 390) is odd, in particular equal to one.

7. The method according to claim 5 or 6, characterized in that the from the at least one iteration step (155, 255, 390) determined target speed (n _se t, n _S et, base, n _S et, eiw) is applied with a safety value .

8. The method according to any one of claims 5 to 7, characterized in that in a double-flow pump (205) with two channels, in particular a high-pressure channel (221) and a separate low-pressure channel (220) after each iteration step (155) for each channel a target speed (n _S et, HP, n _S et, Lp) is determined and the pump (205) is operated with the maximum target speed (n _se t, base) _{required for one of the two target volume flows (Qcooi, Qs ys).}

9. The method according to any one of claims 5 to 7, characterized in that in a double-flow pump (305) with two channels, namely a high pressure channel (321) and one with this by means of a hydraulic coupling (370), in particular a pressure limiting valve (375 ) connected Nie derdruckkanal (320) after each iteration step for each channel a target speed (n _S et, HP, n _S et, Lp) is determined, the maximum required for one of the two target volume flows required target speed (n _se t, base) and determined this target speed (n _S et, base) is corrected iteratively with a size of a volume exchange via the hydraulic coupling (370).

10. The method according to claim 9, characterized in that the size of the volume exchange from the current efficiencies (V, HP, V, LP) of the pump (305) at the current target speed (n _set, base) of the low-pressure channel (320) and the High pressure channel (321) are determined.