DE102020101159A1 - Electric motor vehicle with coolant cooler and associated resistance heating device - Google Patents

Abstract

An electric motor vehicle 1 comprises a cooling system 2, which has at least one electric traction motor 7; 11, a traction battery 6, a coolant pump 16; 17, a coolant cooler 14 and a resistance heating device 20 are integrated, the resistance heating device 20 being integrated in the coolant cooler 14 or the resistance heating device 20 and the coolant cooler 14 being formed separately, wherein then in a functional position of a coolant distribution system coolant by means of the coolant pump 16; 17 can be conveyed first through the resistance heating device 20 and then through the coolant cooler 14. The resistance heating device 20 and possibly also the coolant pump 16; 17 of such a motor vehicle can be put into operation in the event of a determined impairment of the coolant cooler 14 by snow and / or ice in order to thaw the snow and / or the ice.

Description

The invention relates to an electric motor vehicle with a cooling system. An electric motor vehicle is understood to be a motor vehicle that can at least temporarily be driven exclusively by means of one or more electric traction motors. This therefore includes, in particular, battery-electric motor vehicles, electric motor vehicles in which the electrical drive energy is made available by means of a fuel cell, and exclusively electrically driven hybrid vehicles which also have an internal combustion engine.

In the case of electric motor vehicles and especially those that are not designed as hybrid vehicles, at ambient temperatures around or below 0 ° C the problem can arise that a coolant cooler of a cooling system of the respective motor vehicle, which is provided for this purpose, temporarily accumulates waste heat during operation of the motor vehicle to the ambient air, is affected by snow and ice. This applies in particular when the motor vehicle is being driven when it is snowing, which can lead to the coolant cooler, which is exposed to a flow of ambient air via passage openings in the body of the motor vehicle, becoming clogged with snow. An effective flow through the coolant cooler can then be prevented by the snow. Such a clogging of the coolant cooler with snow can also affect the functionality of a loudspeaker which is intended to generate an artificial driving noise of the electric motor vehicle, as is sometimes required by law, and which for this purpose is often arranged directly in front of the coolant cooler. Since when an electric motor vehicle is operated at temperatures close to or below 0 ° C there is usually little or no thermal energy in the cooling system that is to be dissipated to the environment via the coolant cooler, it can happen that the coolant cooler has a remains clogged with snow for a relatively long time. This can have a negative effect on the operation of the corresponding motor vehicle, even if the cooling function of the coolant cooler is not used in principle. This applies in particular if the cooling system is also used to control the temperature or to heat the interior of the motor vehicle. For this purpose, it can also be provided that heat is withdrawn from the air flowing through the coolant cooler in order to use this in a heat pump process for heating the interior. This functionality can be impaired by a cooler clogged with snow. A comparable problem can arise if water, for example condensation water, accumulates in the coolant cooler, which freezes as a result of a subsequent exposure of the motor vehicle to a correspondingly cold environment and thereby in particular impairs the functionality of a radiator fan assigned to the coolant cooler.

the DE 10 2010 002 018 A1 discloses a heating system for an electrically drivable motor vehicle in which two thermoelectric heat pump elements, which can in particular be in the form of Peltier elements, are connected to one another via a cooling circuit, a drive component also being integrated into this cooling circuit. Furthermore, a resistance heating element should be able to be integrated into the cooling circuit.

The invention was based on the object of preventing the functionality of a coolant cooler of an electric motor vehicle from being impaired by snow and ice.

This object is achieved by means of a motor vehicle according to claim 1. A method for operating such a motor vehicle is the subject of patent claim 9. Advantageous embodiments of the motor vehicle according to the invention and preferred embodiments of the method according to the invention are subjects of the further patent claims and / or result from the following description of the invention.

According to the invention, an electric motor vehicle is integrated with a cooling system that includes at least one electric traction motor, a traction battery, a coolant pump, a coolant cooler and an (electrical) resistance heating device, in particular a PTC heating device, the resistance heating device being integrated in the coolant cooler or the resistance heating device and the coolant cooler are formed separately, in which case, in a (first) functional position of a coolant distribution system of the cooling system, coolant can be conveyed by means of the coolant pump first through the resistance heating device and then, in particular immediately thereafter (i.e. without a functional heat source or heat sink arranged in between) through the coolant cooler.

A “coolant cooler” is understood to mean a heat exchanger in which the coolant of the cooling system is to be cooled by a transfer of thermal energy to ambient air that flows through and / or around the heat exchanger. A heating system heat exchanger in which such a heat transfer is also provided to ambient air, but with the aim of controlling the temperature of this ambient air, which is then supplied to an interior of the motor vehicle do not fall under the aforementioned definition of a coolant cooler.

The resistance heating device and possibly also the coolant pump of such a motor vehicle can advantageously be put into operation according to a method according to the invention for operating a motor vehicle if the coolant cooler is determined to be impaired by snow and / or ice in order to thaw the snow and / or ice . Corresponding operation of the resistance heating device with the aim of thawing the snow and / or the ice can in particular (only) be provided until the snow and / or the ice has thawed.

An impairment of the coolant cooler by snow and / or ice can be determined on the one hand on a sensor-based determination of the actual presence of snow and / or ice in or on the coolant cooler. There is also the possibility of using a model to determine a probability of such an impairment based on determined parameters. Such parameters can be, for example, the outside temperature or known weather conditions in which the motor vehicle was operated, which can be detected, for example, on the basis of the use of a windshield wiper. According to a particularly simple embodiment, the successive start-ups of the motor vehicle at ambient temperatures less than or equal to 0 ° C can be automatically counted to determine a (potential) impairment of the coolant cooler due to snow and / or ice, with the resistance heating device in It is operated to thaw any snow and / or ice that may be present. A sensor-based determination, which is relatively complex in terms of construction, can therefore be dispensed with.

The implementation of a method according to the invention, ie the commissioning of the resistance heating device to thaw snow and / or ice, can be carried out while the motor vehicle is being driven and / or during a charging operation in which the traction battery is charged by a current-carrying connection to an external electrical energy source become. Implementation during a charging operation can be advantageous because the electrical energy required for operating the resistance heating device can be provided by the external energy source. In contrast to this, implementation during driving operation can result in the electrical energy required to operate the resistance heating device no longer being available for driving the traction motor and thus reducing the range of the motor vehicle. Against this background, it can also be useful to carry out a method according to the invention or the operation of the resistance heating device with the aim of thawing snow and / or ice present in and / or on the coolant cooler exclusively while the motor vehicle is being charged.

According to a preferred embodiment of a motor vehicle according to the invention, the cooling system can have a configuration in which the traction motor, the coolant cooler and an associated bypass, the traction battery, a first coolant pump and a second coolant pump are integrated in a series circuit in a main circuit of the cooling system. A DC-DC converter and / or a charger and / or power electronics can preferably also be integrated into this main circuit. Furthermore, the cooling system can also comprise a first short-circuit line which integrates the coolant-refrigerant heat exchanger and which is arranged in such a way that it bridges a section of the main circuit that integrates the traction battery and the first coolant pump. In addition, a second short-circuit line can also be provided, which is arranged in such a way that it bridges a section of the main circuit that integrates the traction battery, the first coolant pump and the branches to the first short-circuit line. As a result, an advantageous functionality can be implemented despite a very simple structure of the cooling system. In particular, in such a cooling system, a particularly simple control of the needs-based distribution of the coolant in the cooling system can be implemented by having a first distribution device in at least one branch to the first short-circuit line, in particular in the form of a valve that can be actively controlled by means of a control device of the motor vehicle, and in at least a branch to the bypass, a second distribution device, in particular in the form of an independently acting thermostatic valve, is integrated. In particular, it can be made possible to implement a needs-based distribution of the coolant exclusively by means of these two distribution devices or additionally with a single further valve device, which can preferably also be designed in the form of an actively controllable valve.

In such a cooling system of a motor vehicle according to the invention, the resistance heating device can advantageously be integrated either into the main circuit or into the first short-circuit line. When the resistance heating device is integrated into the main circuit, it could then preferably be provided that it is integrated upstream of the coolant cooler in the section of the main circuit bridged by the bypass. Preferably, however, can be provided Integration of the resistance heating device into the first short-circuit line in order to advantageously enable it to be used not only for defrosting snow and / or ice that is in and / or on the coolant cooler, but also for temperature control or respectively for heating an interior of the motor vehicle and / or the traction battery.

To achieve this, a motor vehicle according to the invention can basically provide that, in the first functional position of the coolant distribution system, coolant can be conveyed in a first coolant circuit which (possibly exclusively, in addition to one or more distribution devices of the coolant distribution system and the coolant pump or several coolant pumps) has one / includes the coolant-refrigerant heat exchanger of an air-conditioning unit, the resistance heating device and the coolant cooler and possibly also the traction battery, while in a second functional position of the coolant distribution system, coolant can be conveyed in a second coolant circuit, which (if necessary exclusively, in addition to one or more distribution devices of the Coolant distribution system and the coolant pump or a plurality of coolant pumps,) includes the coolant-refrigerant heat exchanger, the resistance heating device and the traction battery, dabe i excludes the coolant cooler. In the preferred embodiment of the cooling system with the main circuit and first and second short-circuit line, a (possibly third) distribution device of the coolant distribution system can be integrated into the first short-circuit line, whereby coolant arriving at this can be diverted into an overflow line if necessary by means of this distribution device which opens into the main circuit and in particular into the section of the main circuit bridged by the bypass. The exclusion of the coolant cooler from the second coolant circulation ensures that the heat output introduced into the coolant by the resistance heating device is transferred as exclusively to the coolant-refrigerant heat exchanger of the air conditioning unit and the traction battery, but at least not released to the environment in the coolant cooler will. The thermal energy generated by the resistance heating device is consequently used functionally as completely as possible.

An “air conditioner” is understood to mean a device by means of which air that is to be supplied to an interior of the motor vehicle can be tempered, which can require both heating and cooling of the air. The air conditioning unit can preferably be designed in the form of a cycle device for performing a thermodynamic cycle and for this purpose at least one compressor for compressing the then gaseous refrigerant, a condenser for liquefying the previously gaseous refrigerant with the release of thermal energy, a throttle for in a refrigerant-receiving circuit system Reduction of the pressure of the then liquid refrigerant and an evaporator for evaporating the previously liquid refrigerant while absorbing thermal energy are integrated. Furthermore, such a cycle device of the air conditioner can also include a pump for conveying the refrigerant within the cycle system. In a configuration of the air conditioning device that includes such a cycle device, it can in particular be provided that the coolant-refrigerant heat exchanger integrated into the cooling system is the evaporator of the cycle device. The air conditioning unit can also be operated as a heat pump, so that the heat energy absorbed in the coolant-refrigerant heat exchanger, together with the energy introduced into the refrigerant by the compressor (overpressure), is used as useful heat in the condenser for the temperature control of the interior of the motor vehicle intended air is transmitted. It can also be provided that thermal energy which is transferred from the coolant to the refrigerant of the air conditioning unit in the coolant-refrigerant heat exchanger is used to cool the traction battery, i.e. active cooling of the traction battery can then be implemented by means of the air conditioning unit.

• 1: ein erfindungsgemäßes Kraftfahrzeug gemäß einer ersten Ausgestaltungsform und;
• 2: ein erfindungsgemäßes Kraftfahrzeug gemäß einer zweiten Ausgestaltungsform.

The invention is explained in more detail below with reference to the design examples shown in the drawings. The drawings show, each in a schematic representation:

• 1 : a motor vehicle according to the invention according to a first embodiment and;
• 2 : a motor vehicle according to the invention according to a second embodiment.

the 1 and 2 each show a motor vehicle according to the invention in greatly simplified representations 1 with a cooling system 2 . The cooling systems 2 each comprise a first drive unit as functional components integrated therein 3 that, in serial connection in the cooling system 2 , a DC-DC converter 4th , a first, wired charger 5 for charging a traction battery 6th , a first electric traction motor 7th assigned power electronics 8th as well as the first traction motor 7th includes. The first drive unit 3 can for example be assigned to a rear axle of the motor vehicle or be provided to drive the wheels of this rear axle. Furthermore, the cooling system is integrated 2 a second drive unit 9 , which can be assigned, for example, to a front axle of the motor vehicle can, and the, in series connection in the cooling system 2 , a second, wireless (inductive) charger 10 , one to a second electric traction motor 11 assigned power electronics 12th as well as the second traction motor 11 includes. The first drive unit 3 and the second drive unit 9 are in parallel strands of a main circle 13th of the cooling system 2 integrated. In this main circle 13th are still a coolant cooler 14th , as well as an associated bypass 15th at a junction 31 begins a first electric coolant pump 16 who have favourited traction battery 6th and a second electric coolant pump 17th integrated.

The cooling systems 2 according to the 1 and 2 furthermore each comprise a first short-circuit line 18th who have favourited the traction battery 6th and the first coolant pump 16 comprehensive section of the main circle 13th bridged and in which a coolant-refrigerant heat exchanger 19th of an air conditioner, which is otherwise not shown, as well as a downstream (with respect to an intended flow direction of coolant in the first short-circuit line 18th ) of the coolant-refrigerant heat exchanger 19th arranged heating device 20th ; 21 are integrated. In the motor vehicle 1 according to the 1 is just this one heating device 20th provided, which is designed as a resistance heating device. In the motor vehicle 1 according to the 2 is this heating device 21 however, an additional heating device 21 (preferably in the form of a PTC heating device or a so-called "block heater"), as there is still a resistance heating device 20th upstream (with respect to an intended flow direction of coolant in the main circuit 13th ) of the coolant cooler 14th in that of the bypass 15th bridged section of the main circle 13th is arranged. Alternatively, the resistance heater 20th in the motor vehicle 1 according to the 2 also in the coolant radiator 14th itself or in another component of the cooling system 2 in particular immediately upstream of the coolant cooler 14th can be arranged, be integrated.

The cooling systems 2 according to the 1 and 2 furthermore each comprise a second short-circuit line 22nd who have favourited the traction battery 6th , the first coolant pump 16 as well as the branches 23 to the first short-circuit line 18th comprehensive section of the main circle 13th bridged. In this second short-circuit line 22nd no functional component of the respective cooling system is integrated.

The mentioned functional components of the cooling systems 2 are in each case by means of a plurality of coolant lines and by means of a coolant distribution system that is used in the cooling system 2 according to the 1 a total of three distribution devices, namely two switching valves 24 , 25th in the form of 3/2-way valves and a thermostatic valve 26th and in the cooling system 2 according to the 1 only two distribution devices, namely a switching valve 24 in the form of a 3/2-way valve and a thermostatic valve 26th , includes.

By means of the respective thermostatic valve 26th , which can be designed for example in the form of a purely passive valve actuated by means of an expansion element, a needs-based distribution of coolant to the coolant cooler can be achieved 14th and the bypass 15th respectively.

By means of the switching valve 24 in the motor vehicle 1 according to the 1 or by means of a first (24) of the switching valves 24 ; 25th in the motor vehicle 1 according to the 2 , that is the branch 23 to the first short-circuit line 18th which is located downstream of the traction battery can be from the traction battery 6th incoming coolant either further along the main circle 13th and / or in the first short-circuit line 18th be guided.

The second switching valve 25th of the motor vehicle 1 according to the 1 is, however, downstream of the resistance heater 20th into the first short-circuit line 18th integrated. By means of this second switching valve 25th can coolant that is via the first short-circuit line 18th has flowed, if necessary and completely or partially into an overflow line 30th are diverted upstream of the coolant cooler 14th in the bypass 15th bridged section of the main circle 13th flows out.

The cooling systems 2 each still have an expansion tank 27 on the one hand via a connecting line 28 and on the other hand via a vent line 29 with different sections of the coolant routing of the respective cooling system 2 connected is.

The designs of the motor vehicles 1 according to the 1 and 2 allow for a determined impairment of the coolant cooler 14th to thaw this snow and / or this ice by means of snow and / or ice located in and / or on this, on the one hand by the respective resistance heating device 20th is put into operation. On the other hand, in the motor vehicle 1 according to the 1 at least the first coolant pump 16 and in the motor vehicle 1 according to the 2 at least the second coolant pump 17th put into operation. This achieves that by means of the respective resistance heating device 20th heated coolant to the coolant cooler 14th is promoted to ensure the thawing of the snow or ice located in and / or on this.

Unless in a motor vehicle 1 according to the 2 an integration of the resistance heating device 20th in the coolant radiator 14th itself is provided, it may also be possible that defrosting in and / or on the coolant cooler 14th existing snow and / or ice even without the operation of one of the coolant pumps 16 ; 17th can be achieved because the thermal energy provided for defrosting is generated directly at the point required for this.

The car 1 according to the 1 points in comparison to that according to 2 has the advantage that only one (resistance) heating device 20 is provided, which on the one hand, in the manner described, is required for defrosting in and / or on the coolant cooler 14th located snow and / or ice can be used, with this coolant in a first functional position of the coolant distribution system and specifically in corresponding switching positions of the switching valves 24 , 25th in a first coolant circulation (in the 1 marked with additional arrows drawn with continuous lines) next to the switching valves 24 , 25th only the coolant-refrigerant heat exchanger 19th who have favourited Resistance Heater 20th , the coolant cooler 14th , the first coolant pump used to deliver the coolant 16 as well as the traction battery 6th includes. In addition, this can be a resistance heating device 20th can be used to introduce thermal energy into the coolant, which is in a second functional position of the coolant distribution system or in corresponding switching positions of the switching valves 24 , 25th in a second coolant circuit (in the 1 with additional arrows drawn with dashed lines) next to the switching valves 24 , 25th only the coolant-refrigerant heat exchanger 19th who have favourited Resistance Heater 20th , the first coolant pump used to deliver the coolant 16 as well as the traction battery 6th includes and consequently the coolant cooler 14th excludes. The one from the resistance heater 20th Provided thermal energy can then be used in an advantageous manner to the traction battery 6th and / or via the coolant-refrigerant heat exchanger 19th an interior of the motor vehicle 1 to temperature.

A corresponding functionality is also available in the motor vehicle according to FIG 2 provided, the thermal energy required for this from the additional heating device 21 is made available and wherein coolant by means of the first coolant pump 16 in one next to the switching valve 24 only the first coolant pump 16 who have favourited traction battery 6th , the coolant-refrigerant heat exchanger 19th as well as the additional heating device 21 comprehensive coolant circulation (in the 2 marked with additional arrows drawn with dashed lines). The heat output that is required on the one hand for defrosting in and / or on the coolant cooler as required 14th located snow and / or ice and on the other hand for a temperature control of the traction battery 6th and / or the interior of the motor vehicle 1 are required in the motor vehicle 1 according to the 2 thus from two different heating devices 20th , 21 made available.

List of reference symbols

1

Motor vehicle

2

Cooling system

3

first drive unit

4th

DC-DC converter

5

first charger

6th

Traction battery

7th

first traction motor

8th

Power electronics of the first traction motor

9

second drive unit

10

second charger

11

second traction motor

12th

Power electronics of the second traction motor

13th

Main circuit of the cooling system

14th

Coolant cooler

15th

Bypass to the coolant cooler

16

first coolant pump

17th

second coolant pump

18th

first short-circuit line

19th

Coolant-refrigerant heat exchanger

20th

Resistance heater

21

additional heating device

22nd

second short-circuit line

23

Branch to the first short-circuit line

24

first switching valve

25th

second switching valve

26th

Thermostatic valve

27

surge tank

28

Connecting line

29

Vent line

30th

Overflow line

31

Branch to the bypass

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102010002018 A1 [0003]

Claims (10)

Motor vehicle (1) with a cooling system (2) that - an electric traction motor (7; 11), - a traction battery (6), - a coolant pump (16; 17), - A coolant cooler (14) and - A resistance heating device (20) integrated, wherein - The resistance heating device (20) is integrated into the coolant cooler (14) or - the resistance heating device (20) and the coolant cooler (14) are formed separately, wherein then in a (first) functional position of a coolant distribution system coolant by means of the coolant pump (16; 17) first through the resistance heating device (20) and then through the coolant cooler (14) is fundable. Motor vehicle (1) according to Claim 1 , characterized by - a main circuit integrating the traction motor (7, 11), the coolant cooler (14) and an associated bypass (15), the traction battery (6), a first coolant pump (16) and a second coolant pump (17) in series ( 13), - a first short-circuit line (18) which integrates a coolant-refrigerant heat exchanger (19) of an air conditioning unit and bridges a section of the main circuit (13) comprising the traction battery (6) and the first coolant pump (16), and - a second Short-circuit line (22) which bridges a section of the main circuit (13) comprising the traction battery (6), the first coolant pump (16) and the branches (23) to the first short-circuit line (18) Motor vehicle (1) according to Claim 2 , characterized in that a first distribution device (24) is integrated in at least one branch (23) to the first short-circuit line (18) and a second distribution device (26) of the coolant distribution system is integrated in at least one branch (31) to the bypass (15). Motor vehicle (1) according to Claim 2 or 3 , characterized by a DC-DC converter (4) and / or a charger (5, 10) and / or power electronics (8, 12) which is / are integrated into the main circuit (13). Motor vehicle (1) according to one of the Claims 2 until 4th , characterized in that the resistance heating device (20) is integrated in the main circuit (13) or in the first short-circuit line (18). Motor vehicle (1) according to Claim 5 , characterized in that the resistance heating device (20) is integrated upstream of the coolant cooler (14) in the section of the main circuit (13) bridged by the bypass (15). Motor vehicle (1) according to one of the Claims 1 until 5 , characterized in that - in the first functional position of the coolant distribution system, coolant can be conveyed in a first coolant circuit which comprises a / the coolant-refrigerant heat exchanger (19) of an air conditioner, the resistance heating device (20) and the coolant cooler (14) and - In a second functional position of the coolant distribution system, coolant can be conveyed in a second coolant circuit which includes the coolant-refrigerant heat exchanger (19), the resistance heating device (20) and the traction battery (6) and excludes the coolant cooler (14). Motor vehicle (1) according to one of the Claims 2 until 5 and according to Claim 7 , characterized in that a (third) distribution device (25) of the coolant distribution system is integrated into the first short-circuit line (18), with the (third) distribution device (25) being able to divert coolant arriving at this into an overflow line (30), if necessary opens into the main circle (13). The method for operating a motor vehicle (1) according to any one of the preceding claims, characterized in that if the coolant cooler (14) is determined to be impaired by snow and / or ice, the resistance heating device (20) is put into operation in order to protect the snow and / or Thaw ice. Procedure according to Claim 9 , characterized by being carried out during a driving operation and / or during a charging operation of the motor vehicle (1).

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