DE102005003881A1 - Hybrid drive unit cooling controlling method for hybrid vehicle, involves controlling electrical input of coolant pump based on temperature of electrical engine and/or electronic devices formed in engine - Google Patents

Abstract

The invention relates to a method for controlling a cooling of at least one electric machine (14) and / or electronic components (24, 34) of a motor vehicle, in particular a hybrid vehicle, in which an internal combustion engine (12 ) and the at least one electric machine (14) form a vehicle drive unit (10), wherein at least one cooling circuit (42) encloses the at least one electric machine (14) and / or the electronic components (24, 34) and a coolant by means of an electric Coolant pump (60) through the cooling circuit (42) is conveyed.
It is provided that an electrical power consumption of the electric coolant pump (60) is controlled or regulated as a function of at least one temperature of the at least one electrical machine (14) and / or the electronic components (24, 34). In particular, in stop phases of the internal combustion engine (12), the relevant component temperatures of the electric drive unit (48) are monitored and, if necessary, a control of the electric coolant pump (60) is carried out for cooling.

Description

The The invention relates to a method for controlling a cooling of at least one electric machine and / or of the at least an electrical machine associated electronic components a motor vehicle, in particular a hybrid vehicle, in which an internal combustion engine and the at least one electric machine form a vehicle drive unit. The invention further relates one for execution of the procedure Motor vehicle.

electrical Machinery comes in today's motor vehicles a diverse and growing importance. You can in hybrid vehicles together with an internal combustion engine Hybrid drive unit train or alone in electric vehicles serve the vehicle drive. In addition, they can be next to the vehicle drive or alternatively to this the function of a starter generator, in particular an integrated starter, for starting an internal combustion engine or have other functions.

In Hybrid vehicles are essentially serial or parallel Hybrid concepts differ, with mixed forms are known. In the case of the serial hybrid concepts, vehicle propulsion takes place exclusively via the electric machine while the internal combustion engine over a separate generator the electric current for charging one, the electric machine feeding energy storage or for the Direct supply of the electric machine generated. In contrast, today in car applications frequently Hybrid concepts used in which the vehicle drive both for the Internal combustion engine as well as represented by the electric motor can. In parallel concepts, the aim is basically the internal combustion engine predominantly in low-efficiency operating situations to operate. The electrical machines used can be here either motor or generator operate. So will be about the electric motor in motor operation typically in operating points with higher Supporting vehicle loads switched on to the internal combustion engine. In addition, she can do the function a starter motor for take over the internal combustion engine. In contrast, the e-machine in the internal combustion engine drive is predominant operated as a generator, wherein a thus generated electric power the e-machine, for example, to charge the energy storage and / or used to supply an electrical system. in the Case of a hybrid power split concept with more than one Electric machine can also be the regenerative operation of an electric machine to be used for feeding another. Furthermore, usually will at least part of a braking power driven by the generator E-machine applied (recuperation), taking part of the mechanical energy loss is converted into electrical energy. It is in hybrid concepts Generally advantageous that the electric machines compared to conventional claw pole generators work with better efficiencies.

The comprise individual components of an electric drive unit the electric machine itself, inverter, energy storage (In particular capacitor memory) and the like. As a result of her high converted electrical power and the resulting heat generation These components have an increased cooling demand. For realization the cooling of the Components are predominantly solid heat sinks made of aluminum or copper used, which are in contact with the components. The heat dissipation over a liquid Coolant, which by existing in the heat sinks Drilling is passed. Alternatively, in particular for the cooling of Electronic components known the boiling bath cooling. For this purpose, the Heat through Evaporation of a (electrically non-conductive) liquid dissipated which is in direct contact with the respective component. The evaporated liquid will then over connected heat exchangers cooled again and condenses, with the heat over a coolant discharged from the system becomes. In any case, finally, the dissipation of electrical heat loss via a internal engine cooling circuit the internal combustion engine or a separate low-temperature circuit, for what coolant (Cooling water) through the heat sink or heat exchangers (Boiling bath) is directed. In general, only a partial flow of the engine cooling circuit for cooling the power electronics used.

To promote the coolant through the or the cooling circuits either mechanically or electrically driven feed pumps (cooling water pumps) are used. A problem with the use of mechanically driven by the internal combustion engine feed pumps is in hybrid vehicles, that movement of the cooling medium and thus the heat removal from the system only takes place as long as the engine is in operation. If the internal combustion engine is switched off, as can generally be the case in hybrid vehicles in standstill phases (for example in the case of traffic light stops) or overrun phases (in the case of vehicle deceleration), there is no further flow through the individual components of the power electronics. Furthermore, even after stopping the vehicle no further cooling, which may possibly be required by Nachheizvorgänge. When using an electric pump, there is a need to compromise between the high to find the required mass flow for engine cooling on the one hand and an optimal pressure loss for cooling the power electronics with engine off, on the other hand, since the latter require significantly lower mass flows than the engine cooling. For this purpose, it is known to control the electric pump by a corresponding pulse width modulation (PWM control). Due to the multiple energy conversion, the operation of the electric feed pump is associated with some disadvantages over the mechanical versions.

task The present invention is therefore a method for cooling the Components of an electric drive unit of motor vehicles, in particular of hybrid vehicles, available too the efficiency of electrically driven feed pumps improves and at the same time extends the life of the pump. there should always have a sufficient cooling capacity be ensured of the electric drive unit.

These The object is achieved by a method having the features of the claim 1 solved. In that (especially after a stop of the internal combustion engine) an electrical power consumption of the at least one electrical driven coolant pump dependent on of at least one temperature of the at least one electric machine and / or the electronic components, such as power electronics, Pulse inverters, converters, energy storage and / or the like, which are assigned to the electrical machine, controlled or is regulated, there is a needs-based use of the pump in Vote with the actual cooling requirement of the electric drive. By the electric coolant pump only then, only as intense and only as long as a cooling requirement the life of the pump can be extended significantly and at the same time the electrical energy requirement for operating the pump be reduced. At the same time always after switching off the internal combustion engine adequate cooling the electrical machine and the associated electronic Components guaranteed.

to Determination of the cooling requirement the electric drive unit must have at least one temperature the at least one electric machine and / or the other electronic components are determined. This is done according to a preferred embodiment the invention by temperature measurement by means of arrangement of a or more temperature sensors on the corresponding components. Alternatively, the temperature can also be stored in the engine control over, empirical and / or mathematical models based on suitable reference parameters be determined. Suitable reference parameters are, for example a measured engine or coolant temperature and / or a previously enforced electrical power of the various Components and / or a previous characteristic of an accelerator pedal operation by the driver, who is also a reference for the performance provides.

To an advantageous embodiment of the method according to the invention a lower temperature threshold is specified. Falls below (in particular when the internal combustion engine is switched off) the temperature of the electric motor and / or the electronic components this lower temperature threshold, is on active cooling either entirely dispensed and the coolant pump not operated. Alternatively, in this case, the coolant pump be operated with a minimum of power to one Minimum volume flow for cooling components, causing local vapor bubble formation in the cooling section be avoided.

Farther is provided, when exceeding the lower temperature threshold, the coolant pump operate with a power consumption that coincides with the Temperature of the electrical machine and / or electronic components increases. here we can For example, a graduated course of power consumption with increasing component temperature, a linear relationship between Power consumption and temperature or other types of relationships provided be.

moreover can be provided according to a particularly advantageous embodiment be, even with the internal combustion engine and / or in a shutdown phase of the vehicle, the inventive method for one continue the applicable period of time, that is, the temperature monitoring continue and only when crossing a lower temperature threshold active cooling of the components of the electrical Drive unit perform.

The The invention further relates to a motor vehicle characterized by means is with those in dependence of at least one temperature of the at least one electrical Machine and / or the associated electronic components a electrical power consumption of the at least one coolant pump controlled or regulated. The means comprise in particular a Control logic for execution of the method according to the invention, the can be stored in particular in an engine control.

Further preferred embodiments of the invention will become apparent from the others, in the subclaims mentioned features.

The Invention will be described below in embodiments with reference to FIG associated Drawings explained. Show it:

1 schematically the construction of a hybrid drive unit and

2 schematically the structure of a cooling system of a hybrid drive unit.

In 1 is with 10 Overall, a parallel hybrid drive unit of a hybrid vehicle not shown in detail referred to. The drive of the vehicle takes place optionally or simultaneously by a conventional internal combustion engine 12 (Gasoline or diesel engine) and an electric machine (electric motor) 14 both acting on the same shaft, in particular on the crankshaft of the internal combustion engine 12 , The connection of the electric machine 14 to the engine crankshaft can be done in various ways. That's how the e-machine can work 14 be connected directly or via a coupling with the crankshaft or a belt drive, a toothed belt, a transmission or other non-positive and / or positive connection. internal combustion engine 12 and electric machine 14 are via an automatic or manual transmission 16 with an indicated powertrain 18 connected. The decoupling of the drive shafts of the internal combustion engine 12 or the electric motor 14 from the gearbox 16 via a coupling 20 , which can be opened by operating a non-illustrated clutch pedal by the driver and is closed when not operated. Optionally also between internal combustion engine 12 and electric machine 14 an additional clutch 22 be arranged, which is a separate decoupling of the internal combustion engine 12 from the drive train 18 or from the electric motor 14 allows, which basically gives the advantage that when the internal combustion engine 12 his mechanical frictional resistance must not be dragged. However, this additional savings potential of fuel is a considerable cost, construction and space expenditure compared, so that in this case the additional coupling 22 Although conceivable in principle, but preferably is not provided.

The electric machine 14 , which may be, for example, a three-phase asynchronous or permanently excited synchronous motor, can be operated either in motor or generator mode. In motor operation, the electric motor drives 14 the drive train 18 under consumption of electrical energy (electricity), these from an energy storage 24 refers. The energy storage 24 is preferably a capacitor memory (electric double-layer capacitor), since these memories provide very high peak currents. In addition, capacitor storage compared to batteries (for example, lead-acid, nickel-metal hydride or lithium-ion batteries) significantly higher injection and Ausspeicherwirkungsgrade. The capacitor store is preferably used 24 a known under the trade name UItraCap or SuperCap execution, which has a particularly large surface of the capacitor plates and therefore very high energy densities due to a pronounced surface fine structuring. The energy storage 24 may also be a memory module of several series-connected capacitors or a combined system consisting of a capacitor memory (module) and a parallel-connected battery.

In regenerative operation, however, the electric motor 14 through the internal combustion engine 12 or a thrust of the vehicle operated and converts the kinetic energy into electrical energy to replenish the energy storage 24 as well as to supply one with 26 indicated on-board network of the vehicle. The electrical system 26 includes a variety of electrical loads 28 and may optionally have a backup battery 30 , usually a standard 12V vehicle battery, included. An intermediate DC / DC converter 32 regulates the regenerated energy of the electric motor 14 on the for the electrical system 26 required voltage of 12V down.

Switching the electric machine 14 between engine and generator operation is performed by power electronics 34 , which by means of a built-in inverter at the same time - possibly depending on the type of electrical machine - necessary conversion between direct and alternating current makes. The power electronics 34 also adopts a speed and / or torque control of the electric motor 14 in motor operation or a regulation of the generated electrical power in generator operation.

According to the illustrated concept, the vehicle drive is predominantly by the internal combustion engine 12 , by the designed as a starter generator e-machine 14 is started. The electric machine 14 It also adopts a boost function by being connected to the vehicle drive in high-load situations, in particular when accelerating the vehicle (engine operation). On the other hand, the electric motor has 14 In driving situations in which there is an excess of kinetic energy of the vehicle, a so-called recuperation function, by the kinetic energy in kinetic energy to charge the energy storage in regenerative operation 24 converts and thus simultaneously provides a braking torque. The electric machine 14 has a power of up to 25 kW in so-called mild hybrid vehicles, in particular in the range of 7 to 20 kW, preferably of about 15 kW.

The control of the operation of the internal combustion engine 12 as well as the power electronics 34 done by an engine control unit 36 , in which a control logic (indicated with 38 ) is integrated in the form of a program algorithm with which the inventive method for controlling the cooling of the electric machine 14 and the associated electronic components is executable. Alternatively, the control logic 38 also be provided in a separate control unit.

In 2 is a total with 40 designated cooling system for a hybrid vehicle according to 1 shown, wherein identical elements are denoted by corresponding reference numerals. The simplified illustrated cooling system 40 has a total cooling circuit 42 on, on the one hand a the internal combustion engine 12 including engine cooling circuit 44 and on the other hand a partial cooling circuit 46 , which the total with 48 designated electric drive unit includes. Of these are exemplary here, in addition to the electric machine 14 the energy storage (capacitor storage) 24 as well as the power electronics 34 (which contains the integrated inverter). Of course, here also other electronic components may be included, that of the electric machine 14 are assigned and require cooling.

The engine cooling circuit 44 includes according to the illustrated embodiment, a first coolant pump 50 that mechanically via the internal combustion engine 12 about one with 52 indicated pump drive train is driven and the promotion of a coolant, which is usually water with an antifreeze additive and other additives, through the lines of the cooling circuit 42 causes. In the engine cooling circuit 44 is also a surge tank 54 for the coolant and also a cooler 56 which dissipates the heat absorbed by the coolant by air cooling. The engine cooling circuit 44 corresponds to conventional structure and may additionally contain components for a charge air cooling for an exhaust gas turbocharger or the like.

The partial cooling circuit 46 is parallel to the engine cooling circuit 44 switched, taking at the branching points 58 optionally controllable or switchable valves may be arranged. The supply, not shown in detail, of the individual components of the electric drive unit 48 by the coolant may be in parallel or sequential leadership of the conduit system of the subcooling circuit 46 respectively. The cooling of the electronic components of the electric drive 48 or the electric machine 14 can be done via heat sink made of aluminum or copper and / or via boiling bath cooling. These methods are known in principle and have already been explained in the introduction. The partial cooling circuit 46 has an electric coolant pump 60 on, which is a coolant delivery, especially in the partial cooling circuit 46 causes. The electric coolant pump 60 is preferably by the energy storage 24 fed (indicated by wire 62 ). Operation of the electric coolant pump 60 is preferably done by pulse width modulation (PWM) control by the engine control 36 ,

In 2 are also some examples of some temperature sensors 64 . 66 . 68 . 70 represented, which can be arranged at different locations. For example, one measures in the engine cooling circuit 44 arranged temperature sensor 64 the coolant temperature T _KM , while an alternative to this or additionally in the engine block of the internal combustion engine 12 attached temperature sensor 66 the engine temperature T _M detected. Another temperature sensor 68 is the electric machine 14 assigned and measures the electric motor temperature T _EM . There is also a temperature sensor 70 an example of the electric drive 48 assigned and detects, for example, the temperature T _{E of} the power electronics 34 , the energy storage 24 or the coolant temperature downstream of these components.

This in 2 shown cooling system 40 shows the following function. During operation of the internal combustion engine 12 becomes the mechanical coolant pump 50 through the internal combustion engine 12 driven and takes over the promotion of the coolant through engine and Teilkühlkreis 44 . 46 , due to the usually much higher cooling demand of the internal combustion engine 12 only a relatively low coolant mass flow through the partial cooling circuit 46 the electric drive unit 48 to be led. In this phase, the electric machine 14 mostly operated as a generator and charges the energy storage 24 and / or supplies the electrical system 26 ( 2 ). Due to electrical charge exchange and storage losses as well as friction losses in the electrical machine 14 it comes to heating of the various components of the electric drive unit 48 , Will the electric machine 14 however, to the vehicle drive (alone or together with the internal combustion engine 12 ) or to start the internal combustion engine 12 used, charge exchange and Ausspeicher- and friction losses also lead to component heating. According to the method of the invention, it is checked whether a further cooling requirement of the components of the electric drive 48 is present. For this purpose, first the electric motor temperature T _EM and / or the temperature T _{E of} the electronic components 24 . 34 using the temperature sensors 68 respectively. 70 recorded and with a lower temperature threshold, which can be specified in particular also different for the different components compared. If the lower temperature _{threshold is} undershot by (in particular all) detected temperatures T _EM , T _E , it is possible to dispense with further cooling and the electric coolant pump 60 is not controlled. On the other hand, at least one of the temperatures T _EM , T _E exceeds the lower temperature threshold during operation of the internal combustion engine 12 , is the electric coolant pump 60 driven with a power consumption substantially increases in proportion to the detected temperature T _EM, T _E, it being understood that a maximum power is not exceeded. The electrical cooling is maintained until the continuously determined temperatures T _EM , T _{E of} at least the critical components have fallen below a freely applicable temperature threshold, which may be identical or different with the lower temperature threshold again. Particularly advantageous here, the turn-on and turn-off temperature thresholds can be provided spaced from each other (hysteresis) to a constant switching on and off of the pump 60 to avoid.

If, for example, a vehicle standstill occurs as a result of a traffic light stop, an automatic start-stop system ensures that the internal combustion engine is switched off 12 and thus the mechanical coolant pump 50 so that the coolant is no longer conveyed. Also in this situation, the current temperatures T _E and T _EM or afterheating effects by the internal combustion engine 12 a cooling of the components 14 . 24 . 34 the electric drive unit 48 require. Therefore, the invention provides, even after switching off the engine 12 and / or after parking the vehicle for parking for a predetermined period of time to continue to monitor the temperatures T _E and / or T _EM and falls below the lower temperature threshold to an operation of the electric coolant pump 60 to renounce. Alternatively, it can be provided here, the pump 60 with a minimum power consumption, so that a small flow of coolant through the components of the electric drive 48 is guaranteed. This has the advantage of preventing local accumulation of vapor bubbles in the coolant line. Is when the internal combustion engine 12 The lower temperature threshold, however, exceeded, it comes again to control the electric coolant pump 60 as a function of the temperatures T _E and / or T _EM , until the temperature threshold has fallen below again. In this case, the lower T-threshold for the stop mode can also be specified differently from that for the internal combustion engine operation.

Double-layer capacitors, for example ultracaps, react in the charged state at elevated temperature with a shortened lifetime. In particular, in an installation position in the engine compartment overheating of the condenser memory 24 due to the heat radiation of the internal combustion engine 12 respectively. Does it come with switched off internal combustion engine 12 to an elevated temperature of the capacitor storage 24 (or a combination of battery and capacitor) is therefore provided according to a particularly advantageous embodiment of the invention, the electric coolant pump 60 from the capacitor storage 24 to remove and thus reduce its charge state to a permissible value. In this way, on the one hand to drive the electric coolant pump 60 necessary energy provided without the usually additional existing battery to empty, and on the other hand, the capacitor memory 24 discharged so far that it is protected from damage.

In deviation from the above embodiment, the temperature sensors 64 . 66 68 . 70 , especially the T-sensors 68 . 70 of the electric drive 48 , even completely or partially waived and the relevant temperatures of the components 14 . 24 and or 34 the electric drive unit 48 also be determined by means of an empirical and / or mathematical model stored in the engine control based on suitable reference parameters. Here, empirical models use experimental data, which were obtained, for example, in the engine test bench under typical operating situations and stored in the form of characteristic curves or characteristic diagrams. Mathematical approaches, on the other hand, use physical laws to calculate the temperature. Mixed forms of empirical and mathematical models are also conceivable. Suitable reference parameters are, for example, the engine temperature T _M or coolant temperature T _TM , which with the temperature sensor 66 respectively 64 be measured. Likewise, an electrical power of the various components implemented in the previous operation can be used 14 . 24 . 34 recorded, cumulated and used for the computational determination of the component temperatures T _E and / or T _EM . A preceding characteristic of an accelerator pedal operation by the driver can also be used as a reference for the power applied and thus for determining the temperatures T _E and / or T _EM .

The inventive method has been exemplified for in 2 illustrated configuration explained. However, it is of course also applicable to different cooling systems and / or drive configurations. In particular, the mechanical coolant pump 50 be replaced by another electric pump or a single electric pump can take over the entire coolant delivery. In addition, you can do more or less temperature sensors may be provided at other mounting positions. In addition, the method is also suitable for vehicles with pure electric drive.

10

Hybrid drive unit

12

internal combustion engine

14

electrical machine

16

transmission

18

powertrain

20

clutch

22

additional clutch

24

energy storage

26

board network

28

electrical consumer

30

Backup battery

32

DC / DC converter

34

Power Electronics / Inverter

36

Engine control unit

38

control logic

40

cooling system

42

Total cooling circuit

44

Engine cooling circuit

46

Part cooling circuit

48

electric drive

50

mechanical Coolant pump

52

Pump drive train

54

surge tank

56

cooler

58

branching point

60

electrical Coolant pump

62

management

64

temperature sensor

66

temperature sensor

68

temperature sensor

70

temperature sensor

Claims (11)

Method for controlling a cooling of at least one electric machine ( 14 ) and / or of the at least one electric machine ( 14 ) associated electronic components ( 24 . 34 ) of a motor vehicle, in particular of a hybrid vehicle, in which an internal combustion engine ( 12 ) and the at least one electrical machine ( 14 ) a vehicle drive unit ( 10 ), wherein at least one cooling circuit ( 42 ) the at least one electric machine ( 14 ) and / or the electronic components ( 24 . 34 ) and a coolant by means of at least one electric coolant pump ( 60 ) through the cooling circuit ( 42 ), characterized in that an electrical power consumption of the at least one electric coolant pump ( 60 ) in dependence on at least one temperature of the at least one electrical machine ( 14 ) and / or the electronic components ( 24 . 34 ) is controlled or regulated. Method according to claim 1, characterized in that the at least one temperature of the at least one electrical machine ( 14 ) and / or the electronic components ( 24 . 34 ) by means of at least one temperature sensor ( 68 . 70 ) is measured. Method according to claim 1, characterized in that the at least one temperature of the at least one electrical machine ( 14 ) and / or the electronic components ( 24 . 34 ) is determined by means of an empirical and / or mathematical model as a function of reference parameters, in particular as a function of a previous enforced electrical power and / or a previous accelerator pedal characteristic and / or an engine temperature (T _M ) and / or a coolant temperature (T _KM ). Method according to one of the preceding claims, characterized in that falls below a lower temperature threshold for the at least one temperature of the at least one electric machine ( 14 ) and / or the electronic components ( 24 . 34 ) the at least one electric coolant pump ( 60 ) is not operated or with a minimum power consumption. Method according to one of the preceding claims, characterized in that when a lower temperature threshold for the at least one temperature of the at least one electric machine ( 14 ) and / or the electronic components ( 24 . 34 ) the at least one coolant pump ( 60 ) is operated with a with the at least one temperature substantially increasing power consumption. Method according to one of the preceding claims, characterized in that after a stop of the internal combustion engine ( 12 ), in particular in a parking phase of the motor vehicle, for a predetermined period of time, the temperature-dependent operation of the electric coolant pump ( 60 ) is continued. Method according to one of the preceding claims, characterized in that at a stop of the internal combustion engine ( 12 ), in particular in a parking phase of the motor vehicle, the electric coolant pump ( 60 ) from a capacitor storage ( 24 ) is fed. Motor vehicle with at least one electric machine ( 14 ) and associated electronic components ( 24 . 34 ), in particular hybrid vehicle, in which an internal combustion engine ( 12 ) and the at least one electrical machine ( 14 ) form a vehicle drive unit, with at least one the at least one electric machine ( 14 ) and / or the electronic components ( 24 . 34 ) including cooling circuit ( 42 ) and with at least one electric coolant pump ( 60 ) for conveying a coolant through the cooling circuit ( 42 ), characterized by means with which as a function of at least one temperature of the at least one electric machine ( 14 ) and / or the electronic components associated therewith ( 24 . 34 ) an electrical power consumption of the at least one coolant pump ( 60 ) is controlled or regulated. Motor vehicle according to claim 8, characterized in that the at least one electric machine ( 14 ) associated electronic components at least one pulse inverter ( 34 ) and at least one energy store ( 24 ), in particular a capacitor memory. Motor vehicle according to claim 8 or 9, characterized in that the at least one cooling circuit is a partial cooling circuit ( 46 ) of an overall refrigeration cycle ( 42 ), which also has an engine cooling circuit ( 44 ) for cooling the internal combustion engine ( 12 ). Motor vehicle according to claim 10, characterized in that the total cooling circuit ( 42 ) at least one further electrically and / or mechanically driven coolant pump ( 54 ) having.