Cooling and heating system of a battery-electric vehicle and method for operating the cooling and heating system

Abstract

A cooling and heating system for a battery-electric vehicle and an associated operating method are proposed. The cooling and heating system comprises: - a first coolant loop (1) which runs via a first coolant pump (4), a traction motor (7), a coolant valve (3) and a bypass valve (5), - a vehicle interior heat exchanger (10), wherein the first coolant loop either runs over the vehicle interior heat exchanger or bypasses it, depending on the position of the bypass valve, - a second coolant loop (2) which runs via a second coolant pump (12), an electric auxiliary heater (14), a traction battery (15) and the coolant valve, the two coolant loops being connected either in parallel or in series depending on the position of the coolant valve.

Description

The invention relates to a cooling and heating system of a battery electric vehicle and to a method for operating the cooling and heating system, which comprises a first coolant loop and a second coolant loop and a coolant valve. The two coolant loops are either connected in parallel or in series depending on the position of the coolant valve.Such a cooling and heating system is known from US 2011 / 029 6855 A1.In battery electric vehicles, thermal management is very important in terms of efficient operation and a long life of the vehicle. With regard to efficiency, in the case of a cold ambient temperature, the heating of the passenger interior is problematic, in particular for purely battery-electric vehicles, BEV for short, since a not inconsiderable amount of energy must also be drawn for heating the traction battery and the range of the vehicle accordingly (still) becomes smaller.The present invention is therefore based on the object of specifying a cooling and heating system of a battery-electric vehicle which is as efficient as possible and a method for operating the cooling and heating system.This object is achieved on the one hand by the features of the device claim 1.a first coolant loop passing over a first coolant pump, a traction motor, a coolant valve and a bypass valve,a vehicle interior heat exchanger, wherein the first coolant loop either runs over the vehicle interior heat exchanger or bypasses the latter depending on the position of the bypass valve,a second coolant loop that runs via a second coolant pump, an electric auxiliary heater, a traction battery and the coolant valve,wherein the two coolant loops are either connected in parallel or in series depending on the position of the coolant valve.This interconnection of the system components according to the invention enables heat recovery in such a way that the waste heat of the traction motor absorbed by the coolant is conducted into the vehicle interior heat exchanger, with the result that the electrical energy required by the auxiliary heater for the warming-up of the traction battery and of the vehicle interior can be reduced by the amount of the recovered heat.The object is achieved, on the other hand, by the features of method claim 10.Advantageous embodiments of the invention are the subject of the dependent claims.Further features of the invention will become apparent from the following description and the drawing of a cooling and heating system according to the invention of a battery electric vehicle in five different operating modes. In this case, the comparatively thick lines symbolise the coolant lines through which the coolant is currently flowing. The following are shown: FIG. 1 shows the first operating mode with parallel connection of the coolant loops; FIG. 2 shows the second operating mode with parallel connection of the coolant loops; FIG. 3 shows the third operating mode with series connection of the coolant loops; FIG. 4 shows the fourth operating mode with series connection of the coolant loops; FIG. 5 shows the fifth operating mode with parallel connection of the coolant loops.First, the topology of the cooling and heating system according to the invention is explained with reference to FIG. 1. The cooling and heating system comprises a first coolant loop 1 and a second coolant loop 2, which are either connected in parallel or in series depending on the position of a coolant valve 3. The first coolant loop 1 or the coolant conveyed therein in the arrow direction shown runs via a first coolant pump 4, a bypass valve 5, an on-board supercharger 6, a traction motor 7 which drives the vehicle front axle, an (optional) further traction motor 8 which drives the vehicle rear axle, and the coolant valve 3. Depending on its position, the first coolant loop 1 runs via an air / coolant heat exchanger 9 (according to FIGS. 1 and 3 ) arranged in the return of the further traction motor 8 or bypasses the latter (according to FIGS. 2 and 4 ).The cooling and heating system further comprises a vehicle interior heat exchanger 10. the bypass valve 5 is a 3 / 2-way valve, in the first position of which the first coolant loop 1 bypasses the vehicle interior heat exchanger 10 (according to FIGS. 1 to 3 ) and in the second position of which the first coolant loop 1 extends over the vehicle interior heat exchanger 10 (according to FIG. 4 ). A shut-off valve 11 optionally arranged in the forward flow of the vehicle interior heat exchanger 10 prevents even very small coolant flows from heating the vehicle interior heat exchanger 10 as a result of unavoidable internal leakage in the bypass valve 5.The second coolant loop 2 or the coolant conveyed therein in the arrow direction shown runs via a second coolant pump 12, a refrigerant / coolant heat exchanger 13, via which a refrigeration circuit, not shown, runs, an electric auxiliary heater 14 in the form of a PTC heating element, a traction battery 15 and the coolant valve 3.The two coolant loops 1, 2 are connected via compensating lines 16 and 17 to a common coolant reservoir 18. The two coolant pumps 4 and 12, the coolant valve 3, the refrigerant / coolant heat exchanger 13, the coolant reservoir 18 and optionally the bypass valve 5 and the shut-off valve 11 are combined structurally with the associated coolant lines, branches and interfaces to form a structural unit which can be mounted in the vehicle. Alternatively, the bypass valve 5 and the shut-off valve 11 can form a further structural unit with the vehicle interior heat exchanger 10.The operating modes illustrated in the figures are explained below. The coolant valve 3, which is a rotary slide valve with five connections P 1 to P 5, plays a central role in this case with regard to the interconnection of the two coolant loops 1, 2.FIG. 1 shows the normal cooling mode in which the coolant valve 3 connects the ports P 3 and P 5 on the one hand and the ports P 1 and P 2 on the other hand to one another, so that the two coolant loops 1 and 2 are connected in parallel. The bypass valve 5 is in its first position and the shut-off valve 11 is closed, so that coolant delivered by the first coolant pump 4 completely bypasses the vehicle interior heat exchanger 10 and cools the on-board supercharger 6 and the traction motors 7 and 8. The heat absorbed by the coolant is then released to the vehicle environment via the air / coolant heat exchanger 9.The coolant conveyed by the second coolant pump 12 through the second coolant loop 2 passes through the refrigerant / coolant heat exchanger 13, in which it releases waste heat of the traction battery 15 to the refrigerant, the auxiliary heater 14, which is inactive in this mode, and finally the traction battery 15, cooled by the coolant.The second operating mode according to FIG. 2 differs from the first operating mode in that the coolant valve 3 connects the connections P 3 and P 4 to one another, so that the first coolant loop 1 bypasses the air / coolant heat exchanger 9 and consequently no waste heat of the on-board charger 6 and / or of the traction motors 7, 8 is discharged there to the vehicle environment.FIG. 3 shows the cooling mode at low ambient temperature. In this case, the coolant valve 3 connects the connections P 1 to P 5 on the one hand and the connections P 2 to P 3 on the other hand, so that the two coolant loops 1 and 2 are present in series connection. The waste heat absorbed by the coolant from the traction battery 15, from the traction motors 7, 8 and / or from the on-board charger 6 is only discharged to the vehicle environment via the air / coolant heat exchanger 9.FIG. 4 shows a heating mode of the vehicle interior. In this mode, the coolant valve 3 connects the connections P 1 to P 4 on the one hand and the connections P 2 to P 3 on the other hand, so that the first coolant loop 1 bypasses the air / coolant heat exchanger 9 and the two coolant loops 1 and 2 are likewise present in series connection. The bypass valve 5 is in its second position and the shut-off valve 11 is open, so that coolant delivered by the coolant pumps 4, 12 runs completely over the vehicle interior heat exchanger 10. During the initial starting phase of the vehicle, the auxiliary heater 14 is energized and heats the coolant, which in turn heats the traction battery 15 and then the vehicle interior. The coolant then absorbs waste heat from the traction motors 7, 8, so that this energy is likewise made usable for heating the traction battery 15 and the vehicle interior heat exchanger 10 and correspondingly reduces the energy requirement of the auxiliary heater 14.Following this starting phase-depending on the ambient temperature, for example 15 to 20 minutes later-the coolant absorbs waste heat of the traction motors 7, 8, so that this energy is likewise made usable for heating the traction battery 15 and the vehicle interior heat exchanger 10. The energy requirement of the auxiliary heater 14 which is dependent on the ambient temperature and the desired vehicle interior temperature is accordingly reduced, wherein the auxiliary heater 14 can ideally already be completely switched off after a short time.FIG. 5 shows another heating mode of the vehicle interior. This differs from the second operating mode according to FIG. 2 in that the bypass valve 5 is in its second position and the shut-off valve 11 is open, so that coolant conveyed by the coolant pump 4 and heated up by the waste heat of the traction motors 7, 8 and / or of the on-board supercharger 6 runs completely over the vehicle interior heat exchanger 10.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedUS 2011 / 029 6855 A1

[0002]

Claims

Cooling and heating system of a battery-electric vehicle, comprising: - a first coolant loop (1) which runs via a first coolant pump (4), a traction motor (7), a coolant valve (3) and a bypass valve (5), - a vehicle interior heat exchanger (10), wherein the first coolant loop (1) either runs via the vehicle interior heat exchanger (10) or bypasses the latter depending on the position of the bypass valve (5), - a second coolant loop (2) which runs via a second coolant pump (12), an electric auxiliary heater (14), a traction battery (15) and the coolant valve (3), wherein the two coolant loops (1, 2) are connected either in parallel or in series depending on the position of the coolant valve (3).Cooling and heating system according to claim 1, characterised in that the first coolant loop (1) either runs via an air / coolant heat exchanger (9) or bypasses the latter depending on the position of the coolant valve (3).Cooling and heating system according to Claim 1 or 2, characterized in that the bypass valve (5) is a 3 / 2-way valve, in the first position of which the first coolant loop (1) bypasses the vehicle interior heat exchanger (10) and in the second position of which the first coolant loop (1) runs over the vehicle interior heat exchanger (10).Cooling and heating system according to one of the preceding claims, characterized bya shut-off valve (11) arranged in the forward flow of the vehicle interior heat exchanger (10).Cooling and heating system according to one of the preceding claims, characterized in that the second coolant loop (2) runs via a refrigerant / coolant heat exchanger (13).Cooling and heating system according to one of the preceding claims, characterized in that the first coolant loop (1) runs via an on-board charger (6) and / or via a further traction motor (8).Cooling and heating system according to one of the preceding claims, characterized in that the two coolant loops (1, 2) are connected to a common coolant reservoir (18).Cooling and heating system according to claims 4, 5 and 7, characterised in that the first coolant pump (4), the second coolant pump (12), the coolant valve (3), the refrigerant / coolant heat exchanger (13), the bypass valve (5), the shut-off valve (11) and the coolant reservoir (18) are part of a structural unit which can be mounted in the vehicle.Cooling and heating system according to one of the preceding claims, characterized in that the coolant valve (3) is a rotary slide valve having at least five connections (P1 to P5).Method for operating a cooling and heating system of a battery-electric vehicle, comprising: - a first coolant loop (1) which runs via a first coolant pump (4), a traction motor (7), a coolant valve (3) and a bypass valve (5), - a vehicle interior heat exchanger (10), wherein the first coolant loop (1) either runs via the vehicle interior heat exchanger (10) or bypasses the latter depending on the position of the bypass valve (5), - an air / coolant heat exchanger (9), wherein the first coolant loop (1) either runs via the air / coolant heat exchanger (9) or bypasses the latter depending on the position of the coolant valve (3), - a second coolant loop (2) which runs via a second coolant pump (12), an electric auxiliary heater (14), a traction battery (15) and the coolant valve (3), wherein, in a warm-up phase of the traction battery (15), the two coolant loops (1, 2) are connected in series via the coolant valve (3), the first coolant loop (1) runs via the vehicle interior heat exchanger (10) and bypasses the air / coolant heat exchanger (9), and the coolant is heated by the auxiliary heater (14) and / or the traction motor (7) and heats the traction battery (15) and the vehicle interior heat exchanger (10).

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