KR102343079B1 - Device and method for cooling battery cell modules - Google Patents

Abstract

The present invention relates to a refrigerant circulation system (A) having a refrigerant compressor (1), a refrigerant-cooled main condenser for refrigerant (2), an expansion member (3) and a battery cooler (4) for cooling a battery cell module (6) and a component a coolant line connecting the components with a coolant circulation system B comprising refrigerant lines 5 connecting the 14) relates to a device for cooling a battery cell module (6) comprising: a bypass (23) capable of blocking the coolant flowing to the coolant cooler (11) in the coolant circulation system (B); It is characterized in that it is placed.
The invention also relates to a method for cooling a battery cell module (6).

Description

DEVICE AND METHOD FOR COOLING BATTERY CELL MODULES

The present invention relates in particular to an apparatus and method for cooling a battery cell module of an electric vehicle or a hybrid vehicle having a high voltage energy storage device to be cooled.

The invention further relates to a method of controlling a refrigerant circulation system thermally coupled to a refrigerant circulation system via a coolant cooled condenser.

Various cooling devices and control concepts are known from the prior art for cooling high voltage energy storage devices, also commonly referred to as batteries or accumulators.

DE 10 2013 211 259 A1, for example, discloses a method and a control unit for optimizing the cooling of a high-voltage battery by means of an air conditioner. In this case, the coolant volume flow is reduced in order to increase the high pressure in the refrigerant circulation system, especially when the external temperature is low. Also, US 8,191,618 B2 discloses a heat management method in which a refrigerant circulation system is connected to a coolant circulation system through a heat exchanger. In this case, the heat exchanger is formed to improve battery cooling efficiency as a latent heat storage device.

The prior art has the disadvantage that a decrease in the coolant volume flow leads to a significant decrease in the flow temperature in the coolant-cooled condenser of the refrigerant circulation system. In special cases, the flow temperature is reduced until it reaches the ambient temperature level. In the case of a refrigerant-cooled condenser of the refrigerant circulation system, designed as a heat exchanger, this is achieved by the method applied, wherein the heat transfer is displaced, in particular in the region of the outlet on the refrigerant side. In the coolant-side inlet region, the coolant temperature is already quite close to the coolant condensation temperature level, so that only a small amount of heat can be transferred from the coolant to the coolant at this location. By this method the coolant flow temperature is never increased, only decreased. Overall, a large reduction in the coolant volume flow is equivalent to a reduction in the heat transfer area, so that only a small increase in the refrigerant-side high-pressure level in the refrigerant circulation system can be achieved.

Another disadvantage of the prior art is that the coolant flow temperature is highly dependent on the vehicle speed. This means that more heat can be transferred from the coolant cooler to the ambient air when the vehicle speed is high than when the vehicle speed is low or even at standstill. A high vehicle speed but a low coolant flow temperature is accompanied by a lower high pressure level in the refrigerant cycle, which is also accompanied by a decrease in the cooling capacity of the battery cooler under these conditions. In Fig. 1, a typical cycle according to the prior art is shown as a log(p)h-diagram. The battery cell temperature (T1) of the vehicle battery is a high temperature level, usually exceeding 25°C, because, according to the recent prior art, the cooling requirement is linked with the absolute battery temperature. At the high temperature level, the battery has an optimum efficiency, likewise the high temperature level helps the durability of the battery. According to the prior art, the coolant flow temperature (T3) of coolant-cooled, in particular water-cooled condensers, is at about the level of ambient temperature (T2), which results in a much lower high pressure and lower suction pressure compared to the warm outside temperature. In summary, this results in a very high drive temperature difference (ΔT) equal to T4 between the battery cell temperature (T1) and the suction side saturation temperature of the battery cooler. At low outside temperatures, the maximum cooling capacity of the battery cooler is reduced compared to at high outside temperatures because the suction pressure is significantly lower due to the low suction density and low refrigerant mass flow. Also, the high temperature difference ΔT causes premature overheating of the refrigerant in the battery cooler, which makes it difficult or impossible to achieve a uniform battery cooler.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the efficiency of a refrigerant circulation system in all operating states of a vehicle.

The concept of the invention is that, for example, the coolant flow temperature of the coolant-cooled condenser is increased to a target and actively controlled, not only when the vehicle is stationary, but also while driving. In particular, at low external temperatures, for example below 0° C., the coolant flow temperature is raised to levels above 10° C. by the concept according to the invention. The refrigerant flow temperature is increased by active control of the refrigerant cooler bypass mass flow M2 until the high pressure in the refrigerant circulation system reaches a predetermined target value.

The realization of the above concept gives various advantages for the battery cooling function at the refrigerant cycle level, which will be described in more detail below.

Said task is solved by the subject matter according to the independent claims. Improvements are described in the dependent claims.

The above object of the present invention is particularly solved by a device for cooling a battery cell module, wherein the device includes a refrigerant compressor, a refrigerant cooling main condenser for a refrigerant, an expansion member and a battery cooler for cooling the battery cell module and refrigerant lines connecting the individual components with a refrigerant circulation system having, in this case further provided with a refrigerant circulation system, said refrigerant circulation system comprising a refrigerant pump, a refrigerant cooler and the refrigerant cooled main condenser and refrigerant lines connecting the components do.

The invention is particularly characterized in that, in the coolant circulation system, a bypass capable of blocking the coolant flowing to the coolant cooler is arranged. In the refrigerant control method, the bypass completely bypasses the coolant cooler under certain operating conditions, allows the heated coolant to be provided directly to the main condenser of the refrigerant circulation system, and significantly increases the coolant inlet temperature.

Also, in one preferred embodiment of the present invention, the coolant total mass flow can be divided into partial mass flows by means of coolant valves in the coolant circulation system and is designed so that it can be directed through the bypass and/or the coolant cooler. has been Preferably, the partial mass flows are designed to be adjustable.

A 3/2-way valve is particularly preferably arranged for the division and regulation of the total mass flow of coolant into partial mass flows.

Preferably, a high-pressure pressure sensor is disposed behind the main condenser in the refrigerant flow direction in the refrigerant circulation system.

In addition, a high-pressure pressure sensor is disposed in front of the main condenser in the refrigerant flow direction in the refrigerant circulation system.

Alternatively, a pressure sensor for low pressure is disposed between the expansion member and the refrigerant compressor in the refrigerant flow direction in the refrigerant circulation system.

Further preferred variants of the refrigerant circulation system include further parallel and/or series condensers/gas coolers and/or evaporators and/or expansion element in the refrigerant circulation system, likewise for realizing a wide variety of additional requirements for the refrigerant circulation system. are placed

Further, in a preferred embodiment of the refrigerant circulation system, one or more high-pressure collectors and/or one or more low-pressure collectors are arranged on the low-pressure side in the refrigerant circulation system, and optionally one internal heat exchange flag is placed.

In addition, the object of the present invention is solved by a method for cooling a battery cell module using the above-described device, in which case, the method includes a high pressure in the refrigerant circulation system when the high pressure in the refrigerant circulation system is lower than the target value. It is characterized in that the coolant mass flow through the bypass for coolant is increased until this target value is reached.

Preferably, the pilot control of the coolant valves is performed according to the vehicle speed, and as a result, when the high pressure in the pressure sensor in the refrigerant circulation system is adjusted as the vehicle speed increases, the coolant valve for the coolant cooler is further closed, And the coolant valve for the bypass is additionally opened, and vice versa.

Preferably, the refrigerant circulation system is operated with R1234yf, R134a, R744, R404a, R600a, R290, R152a, R32 and mixtures thereof.

In a further preferred embodiment, an optimum low pressure in the refrigerant circulation system is established as an alternative to the high pressure by regulating the partial mass flow.

An advantage of the present invention is that it is possible to increase the efficiency of the refrigerant circulation system, especially when the external temperature is low.

In addition, it is possible to increase the cooling capacity of the refrigerant circulation system when the external temperature is low, so that fast charging is possible with a current strength that does not change even at a lower external temperature. A low external temperature in the scope of the present invention means a temperature of about 0°C and below 0°C.

It is particularly desirable that the battery cooler design can be designed to be less robust against refrigerant overheating, which can result in significant cost savings. For economic and environmental reasons, a smaller refrigerant charge is required at a lower external temperature, which, in addition to the potential for cost savings on the refrigerant, also comes with a smaller volume refrigerant collector, which in turn gives advantages in terms of cost, space and weight. is preferable.

Additional details, features and advantages of embodiments of the present invention emerge from the following description of embodiments with reference to the accompanying drawings. In the drawing department:
1 is a log(p)h-diagram showing a refrigerant cycle according to the prior art,
2 shows a combined refrigerant and coolant circulation system according to the invention with bypass of the coolant cooler;
3 is a view showing a combined circulation system without a bypass in the coolant circulation system;
4 is a log(p)h-diagram of a low-temperature steam cycle with increasing pressure on the high-pressure side;
5 is a view showing a combined circulation system of the bypass circuit,
6 is a log(p)h-diagram of the cooling cycle in the bypass circuit of the coolant;
8 is a log(p)h-diagram of the steady state,
9 is a control diagram of a coolant valve for bypass and a coolant cooler;
10 shows a combined circulation system with an air-cooled auxiliary condenser with air flaps, and
11 shows a combined circulation system with bypass of the auxiliary condenser.

2 shows a refrigerant circulation system (A) and a refrigerant circulation system (B) coupled through a refrigerant cooling main condenser (2) of this refrigerant circulation system. Said refrigerant circulation system (A) consists in practice of the usual components: a refrigerant compressor (1), a refrigerant-cooled main condenser (2), an expansion member (3), preferably designed as an electronic expansion valve (EXV), a battery cooler (4) ) and refrigerant lines 5 and a pressure sensor 7 or 7a. A preferred position of the pressure sensor in this case is shown as the pressure sensor 7 behind the main condenser 2 in the refrigerant flow direction, alternatively the position of the pressure sensor 7a is shown before the main condenser 2 in the flow direction. has been The battery cooler 4 is in direct contact with these battery cell modules 6 to cool the battery cell modules as required. The coolant circulation system B, shown in the upper region of Figure 2, is actually a coolant pump 8 conveying a total coolant mass flow M12 and two coolant valves 9, 10, preferably designed with an adjustable throttle cross-section. consist of. The coolant valves 9 and 10 jointly control the coolant mass flows M1 and M2 forming the coolant gross mass flow M12 as a partial mass flow. These mass flows are marked with a corresponding dot over the symbol in the figure. A coolant cooler 11 , also referred to as an LTR, and several coolant lines 14 are provided. A coolant flow temperature sensor 15 is arranged in front of the coolant cooled main condenser 2 in the coolant flow direction and measures coolant flow temperature as conceptually indicated. The coolant total mass flow M12 is the partial mass flow M1 flowing through the coolant cooler 11 at the junction 12 and the partial mass guided past the coolant cooler 11 in the bypass 23 for the coolant. It is divided into flow M2. The partial mass streams M1 and M2 of the coolant from below, viewed in the flow direction, are reunited at the confluence 13 , together flow through the main condenser 2 , and then flow back to the coolant pump 8 . The coolant cooler 11 is preferably located in the cooling module of the front end of the vehicle and is overflowed by the amount of air around it, ie the cooling air 16 . The waste heat of the coolant circulation system B can be transferred from the coolant cooler 11 to the cooling air 16 and discharged to the environment by the system.

3 shows a coupled circulatory system which is driven in particular at an external temperature, for example at an external temperature of at least 5°C. To achieve the maximum cooling capacity, the coolant valve 9 is fully open and the coolant valve 10 is fully closed. The coolant gross mass flow M12 thus flows through the coolant cooler 11 , and the coolant bypass 23 is closed. Therefore, as much heat as possible is dissipated from the coolant cooler 11 to the ambient air or to the cooling air 16 .

In Fig. 4, there is shown a log(p)h-diagram according to the low-temperature steam cycle as a typical cycle of the refrigerant circulation system A when the external temperature is high, which is comparable to the illustration of the cooling device shown in Fig. 3 . In the illustrated cooling cycle, the saturation temperature of the high-pressure side is much higher than the ambient temperature T2, and the saturation temperature of the suction side is much lower than the battery cell temperature T1. The temperature difference was divided by ΔT4. The coolant flow temperature T3 of the coolant cooled main condenser 2 is higher than the ambient temperature T2. In this case the coolant flow temperature T3 is measured by the coolant flow temperature sensor 15 , and the battery cell temperature T1 is measured directly in the battery cell module 6 . The ambient temperature T2 corresponds to the temperature of the cooling air 16 .

Figure 5 shows the operation of the device in an unstable state when the external temperature is low, for example less than 5°C. In particular, when the system has just started, and in an unstable condition, where the coolant flow temperature on the coolant flow temperature sensor 15 leading into the coolant cooled main condenser 2 and the ambient temperature of the cooling air 16 are at similar levels, the coolant circulation system A ) it is necessary to raise the coolant flow temperature T3 measured at the coolant flow temperature sensor 15 as quickly as possible in order to increase the high pressure level measured at the pressure sensor 7 or alternatively the pressure sensor 7a in . The coolant valve 9 is fully closed and the coolant valve 10 is fully opened, thereby raising or increasing the coolant flow temperature. The total coolant mass flow M12 thus all goes through the coolant cooler bypass 23 to the main condenser 2 , and in this operating state the coolant cooler 11 is not flowed through by coolant. Therefore, no heat is transferred from the coolant cooler 11 to the cooling air 16, and the coolant flow temperature measured by the coolant flow temperature sensor 15 is transmitted through the coolant cooling main condenser 2 in the coolant circulation system A to the coolant. It is gradually heated by the heat transferred to the circulation system (B).

6 shows a typical cycle of the refrigerant circulation system A corresponding to the circuit shown in FIG. 5 when the external temperature is low, and a predetermined time after system startup. Since the battery cooling requirement is generally coupled to the absolute battery cell temperature T1 of the battery cell module 6 , the battery cell temperature T1 is at a high temperature level similar to when the outside temperature is high. With the coolant cooler bypass 23 fully opened, the coolant flow temperature measured by the coolant flow temperature sensor 15 before entering into the main condenser 2 is either the ambient temperature T2 or the cooling entering the coolant cooler 11 . It is heated much higher than the air inlet temperature of the air 16 . As a result, the saturation temperature on the pneumatic side of the refrigerant circulation system A is higher than the air inlet temperature of the cooling air 16 and rises to a level much higher than the ambient temperature T2. On the one hand, this leads to an increase in the suction pressure level and with it the suction density, the maximum refrigerant mass flow and thus the maximum cooling capacity and a smaller driving temperature difference ΔT, as a result of which the refrigerant in the battery cooler 4 later overheats. and uniform cooling of the battery cell module 6 is possible.

7 shows a cycle when the external temperature is low in a steady state. The system has already been operated for a long time, and the coolant flow temperature at the coolant flow temperature sensor 15 entering the coolant cooled main condenser 2 is at a steady state above the ambient temperature T2, the coolant flow temperature is maintained at a constant level . The temperature level to be adjusted is adapted to the high pressure level measured at the pressure sensor 7 of the refrigerant circulation system A, alternatively at the pressure sensor 7a. In order to maintain the coolant flow temperature at a constant level, the coolant total mass flow M12 is divided into coolant partial mass flows M1 and M2 through adjustment of the open cross-sectional area of the coolant valves 9 and 10 . Heat entering the coolant circulation (B), which may aid in further raising the coolant flow temperature, may be discharged through the coolant cooler (11) to the ambient or cooling air (16). In this case, the greater the partial mass flow M1 , the more heat is dissipated from the coolant cooler 11 into the cooling air 16 , and vice versa. The coolant flow temperature is finally represented as a mixing temperature consisting of two coolant partial mass flows: a coolant mass flow M2 with an associated coolant temperature and a coolant mass flow M1. As the vehicle travels, the amount of air in the cooling air 16 increases on the coolant cooler 11 , as a result of which the coolant cooler transfers more heat to the surroundings. However, in order for the constant coolant flow temperature T3 measured by the coolant flow temperature sensor 15 to be set, the coolant valve 9 is further closed proportionally when the vehicle is running, and the coolant valve 10 is additionally opened, And more coolant is guided through the bypass 23 .

8 is a log(p)h-diagram showing a typical cycle of the refrigerant circulation system (A) when the external temperature is low in the normal state of the circulation system of FIG. 7 described above. In this case, the steady state can be understood as the system has already been running for some time and is in a transient state. Contrary to the illustration of FIG. 7 , the coolant flow temperature T3 as a mixture temperature consisting of a coolant mass flow M2 and a coolant mass flow M1 having an associated coolant mass flow temperature is equal to the coolant temperature at the outlet of the coolant cooler 11 . At the outlet of the water-cooled main condenser 2 having a condenser outlet T5 temperature is changed, ie a temperature coolant cooler outlet T6 is given.

9 shows the control strategy of the coolant valves 9 and 10 . This control strategy or control method is designed such that when the high pressure measured at the pressure sensor 7 or 7a in the refrigerant circulation system A is lower than the optimum high pressure, the coolant valve 9 is closed and the coolant valve 10 is opened. . On the other hand, when the high pressure measured by the pressure sensor 7 or 7a in the refrigerant circulation system A is higher than the optimum high pressure, the refrigerant valve 9 is opened and the refrigerant valve 10 is closed. When the high pressure measured by the pressure sensor 7 or 7a in the refrigerant circulation system corresponds to the optimum high pressure, the opening cross-sectional areas of the refrigerant valves 9 and 10 are maintained.

In addition, pilot control of the coolant valve position according to vehicle speed is desirable, and as a result, when the high pressure measured by the pressure sensor 7 or 7a in the refrigerant circulation system A is set as the vehicle speed increases, the coolant valve 9 is activated. It is further closed and the coolant valve 10 is further opened. When the vehicle speed is reduced, the coolant valve 9 is further opened in a similar manner and the coolant valve 10 is further closed.

Another embodiment of the combined circuit of the refrigerant circulation system and the coolant circulation system is shown in FIG. 10 , in which case an additional air-cooled auxiliary condenser 17 is arranged downstream of the coolant-cooled main condenser 2 . At high external temperatures, the air-cooled auxiliary condenser 17 may dissipate additional heat into the air stream of the ambient air 19 , increasing the overall cooling capacity of the battery cooler 4 . At low external temperatures, it is desirable to increase the high pressure level of the pressure sensors 7 and 7a in the refrigerant circulation system A, as described in the introduction. In this embodiment, the air-cooled auxiliary condenser 17 is flowed through by the ambient air 19 in such a way that this is prevented by additional air flaps 18 , and heat is prevented from being able to be transferred to this ambient air. It is possible.

In FIG. 11 , instead of air flaps, for example a 3/2-way valve 20 or alternatively two separate refrigerant valves, the refrigerant side outlet of the water-cooled main condenser 2 and the refrigerant side of the air-cooled auxiliary condenser 17 are shown. A variant of the embodiment shown in FIG. 10 is shown, expanded to the effect that the air flaps 18 can be omitted in the air-cooled auxiliary condenser 17 when inserted between the inlets. The 3/2-way valve (20) is such that the entire refrigerant mass flow flows through the air-cooled auxiliary condenser (17) when the ambient temperature is high, and the total refrigerant mass flows through the bypass (22) for the refrigerant when the ambient temperature is low. Controlled. By inserting an additional check valve (not shown) between the outlet of the refrigerant side of the air-cooled auxiliary condenser 17 and the node point 21 , the refrigerant movement to the air-cooled sub-condenser 17 can be prevented.

1: Refrigerant Compressor
2: Refrigerant-cooled main condenser
3: Inflatable member, throttle member
4: battery cooler
5: Refrigerant line
6: battery cell module
7/7a: pressure sensor
8: coolant pump
9: Coolant valve, shut-off member
10: coolant valve, shut-off member
11: Refrigerant cooler
12: Junction
13: confluence
14: coolant line
15: coolant flow temperature sensor
16: cooling air
17: Air-cooled auxiliary condenser
18: air flap
19: ambient air
20: 3/2 way valve
21: nodal point
22: refrigerant bypass
23: coolant bypass, coolant cooler bypass
A: Refrigerant circulation system
B: coolant circulation system
T1: battery cell temperature
T2: ambient temperature
T3: coolant flow temperature
T4: temperature difference
T5: condenser outlet temperature
T6: Refrigerant cooler outlet temperature
M1: coolant mass flow 1, partial mass flow
M2: coolant mass flow 2, partial mass flow
M12: coolant total mass flow

Claims (12)

Refrigerant compressor (1), refrigerant cooling main condenser for refrigerant (2), expansion member (3), battery cooler (4) cooling battery cell module (6) and refrigerant lines (5) connecting the components Battery, consisting of a refrigerant circulation system (A) and a coolant circulation system (B) comprising a coolant pump (8), a coolant cooler (11), the coolant cooled main condenser (2) and coolant lines (14) connecting the components A device for cooling a cell module (6), comprising:
A refrigerant is circulated independently in the refrigerant circulation system (A) and a coolant is circulated independently in the refrigerant circulation system (B), wherein the refrigerant and the coolant exchange heat in the refrigerant cooling main condenser (2),
In the coolant circulation system (B), a bypass (23) capable of blocking the coolant flowing to the coolant cooler (11) is arranged,
A high-pressure pressure sensor (7, 7a) is disposed behind or in front of the main condenser (2) in the refrigerant flow direction in the refrigerant circulation system (A),
The device, characterized in that the bypass (23) is closed or opened according to the comparison of the target value with the high pressure measured by the high pressure pressure sensor (7, 7a) in the refrigerant circulation system (A). 2 . The bypass ( 23 ) and/or the bypass ( 23 ) and/or the Device, characterized in that it is designed to be guided through the coolant cooler (11). Device according to claim 2, characterized in that a 3/2-way valve is arranged for regulating the coolant total mass flow (M12) divided into partial mass flows (M1, M2). delete delete Device according to claim 1, characterized in that a pressure sensor for low pressure is arranged between the expansion member (3) and the refrigerant compressor (1) in the refrigerant flow direction in the refrigerant circulation system (A). Device according to claim 1, characterized in that further parallel and/or series condensers/gas coolers and/or evaporators and/or expansion elements are arranged in the refrigerant circulation system (A). The method according to claim 1, wherein one or more high-pressure collectors and/or one or more low-pressure collectors are arranged on the high-pressure side and/or one or more low-pressure collectors on the low-pressure side in the refrigerant circulation system (A), and/or that an internal heat exchanger is arranged Characterized by the device. 9. A method for cooling a battery cell module (6) using a device according to any one of claims 1 to 3, 6 to 8, comprising:
When the high pressure in the refrigerant circulation system is lower than the target value, the coolant mass flow (M2) through the coolant bypass (23) increases until the high pressure in the refrigerant circulation system (A) reaches the target value, characterized in that How to. 10. The high pressure in the pressure sensor (7, 7a) in the refrigerant circulation system (A) according to claim 9, wherein the pilot control of the coolant valves (9, 10) is made according to the vehicle speed, and as the vehicle speed increases When this adjustment is made, the coolant valve (9) is further closed, the coolant valve (10) is further opened and vice versa. Method according to claim 9, characterized in that the refrigerant circulation system (A) is operated with R1234yf, R134a, R744, R404a, R600a, R290, R152a, R32 and mixtures thereof. Method according to claim 9, characterized in that the partial mass flow (M1, M2) is adjusted so that an optimum low pressure is established in the refrigerant circulation system.

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