DESC: Cooling System for Battery in Vehicle

Field of the invention

The present invention relates generally to automotive cooling systems and more particularly, to a cooling system for a battery in a vehicle.

Background of the invention

High voltage (HV) battery is one of the key components for any hybrid / electric vehicle architecture. There are various options of thermal management available for the hybrid electric vehicle in market ranging from air cooling to liquid cooling to refrigerant cooling. Based on the system layout, the HV battery includes an air cooling system. In the current market trends, Li-ion chemistry is the most preferred solution for HV battery pack in an automotive application. The main issue with Li-ion based chemistry is its stringent thermal operating boundaries and safety related concerns. Hence, it is highly required to maintain the HV battery within a specified temperature range.

Accordingly, there is a need to provide a cooling system for a battery in a vehicle that overcomes the above mentioned drawbacks of the prior art.

Object of the invention

An object of the present invention is to ensure that a battery is always in an operating temperature range to deliver optimum performance.

Summary of the invention

Accordingly, the present invention provides a cooling system for a battery in a vehicle. The vehicle includes a front heating, ventilating, and air conditioning (HVAC) unit, an evaporative emission control system, an engine management system, a compressor, a condenser and a battery. The front HVAC unit includes a front evaporator and a front blower. The battery is a high voltage battery pack and includes a plurality of battery cells, an inlet duct and an outlet duct.

The cooling system comprises a pull type blower, a rear heating, ventilating, and air conditioning (HVAC) unit, a solenoid valve, a battery management system, a hybrid control unit and a body function module.

The pull type blower is packaged in an outlet side of the battery to suck air therefrom for releasing in an atmosphere thereby reducing temperature in the battery. The rear HVAC unit is capable turning ON the compressor using the engine management system. The rear HVAC unit includes a rear evaporator and a rear blower.

The solenoid valve is used to control a refrigerant flow to the rear HVAC unit. The battery management system is adapted for controlling and monitoring temperature of the plurality of battery cells and generating corresponding request for starting a cooling mode. The cooling mode is selected from any one of an active cooling mode and a cabin air cooling mode. The temperature of the plurality of battery cells is monitored and controlled by the battery management system by controlling speed of the pull type blower via a pulse width modulation signal. The hybrid control unit receives the cooling mode request from the battery management system for switching ON/OFF the solenoid valve and a relay of the rear blower. The body function module communicates with the rear HVAC unit to turn ON the compressor.

On receipt of the active cooling mode request from the battery management system, the hybrid control unit turns ON the compressor and the front blower, energizes the relay of the rear blower causing the rear blower to run at a constant speed to deliver the required air flow rate and also, turns on the solenoid valve to permit the flow of refrigerant to the rear HVAC unit causing the cooling of the air sucked by the rear HVAC and pushing of the cooled air into the battery. The pull type blower then sucks the air from the battery for releasing into the atmosphere thereby reducing the temperature in the battery. For the cabin air cooling mode, the pull type blower and the rear blower are switched ON to suck a cabin air for the battery cooling and the solenoid valve is switched OFF. For passage of the cabin air and the cooled air from the rear HVAC unit, a single ducting layout without any branch and flaps is utilized.

Brief description of the drawings

Figure 1 shows a ducting layout of a cooling system for a battery in a vehicle, in accordance with the present invention;

Figure 2 shows a schematic drawing of the cooling system for the battery in the vehicle, in accordance with the present invention;

Figure 3 shows a cooling architecture of a high voltage battery pack, in accordance with the present invention;

Figure 4a shows a rear blower relay circuit, in accordance with the present invention;

Figure 4b shows a solenoid valve circuit, in accordance with the present invention; and

Figure 5 shows an algorithm for the high voltage battery cooling, in accordance with the present invention.

Detailed description of the invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.

The present invention provides a cooling system for a battery in a vehicle. The cooling system utilizes control systems like a battery management system and a hybrid control unit for monitoring and controlling the battery cooling (including override of compressor ON and front blower ON) to ensure that the battery is always in an operating temperature range to deliver optimum performance.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.

Referring to figures 1-2, a cooling system (100) for a battery (140) in a vehicle (200) in accordance with the present invention is shown. Specifically, the cooling system (100) is designed for cooling the battery (140) of a hybrid vehicle. However, it is understood that the cooling system (100) may be suitably changed to comply requirements as per the vehicle used.

The vehicle (200) includes a front heating, ventilating, and air conditioning (HVAC) unit (110), an evaporative emission control system (not shown), an engine management system (not numbered), a compressor (120), a condenser (130) and the battery (140). The front HVAC unit (110) includes a front evaporator (104) and a front blower (108). The battery (140) is placed in a battery compartment (150) that is positioned under a second row seat (not shown) of a passenger compartment (not numbered) of the vehicle (200). The battery (140) specifically, a high voltage battery pack includes a plurality of battery cells (not shown), an inlet duct (134) and an outlet duct (138). The outlet duct (138) is routed to reduce a possibility of water entry into the battery (140).

The cooling system (100) comprises a pull type blower (10), a rear heating, ventilating, and air conditioning (HVAC) unit (20), a solenoid valve (30), a battery management system (40) (hereinafter “the BMS (40)”), a hybrid control unit (50) (hereinafter “the HCU (50)”) and a body function module (60) (hereinafter “the BFM (60)”). All the above mentioned components are operably connected to one another.

The pull type blower (10) is packaged in an outlet side (not numbered) of the battery (140) to suck air therefrom for releasing in an atmosphere thereby reducing temperature in the battery (140). The rear HVAC unit (20) and the front HVAC unit (110) are connected to the compressor (120) via an expansion valve (115). The rear HVAC unit (20) is capable of turning ON the compressor (120) using the engine management system (hereinafter “the EMS”). The rear HVAC unit (20) includes a rear evaporator (12) and a rear blower (18). The air from a cabin (not shown) of the vehicle (200) is sucked by the rear HVAC unit (20) and diverted into a vent (not shown) of a rear compartment (not numbered) of the vehicle (200) for passing into the battery compartment (150) via a T-channel (not shown) thus providing cooling to the rear compartment as well as to the battery (140) depending on the battery (140) requirement. In an embodiment, for passage of the cabin air and the cooled air from the rear HVAC unit (20), a single ducting layout (refer figure 1) without any branch and flaps is utilized.

The solenoid valve (30) is positioned between the rear HVAC unit (20) and the expansion valve (115). The solenoid valve (30) is used to control a refrigerant flow to the rear HVAC unit (20). The BMS (40) is adapted for controlling and monitoring temperature of the plurality of battery cells and generating corresponding request for starting a cooling mode. The cooling mode is selected from any one of an active cooling mode and a cabin air cooling mode. The temperature of the plurality of battery cells is monitored and controlled by the BMS (40) by controlling speed of the pull type blower (10) via a pulse width modulation signal (PWM). In an embodiment, the BMS (40) sets the speed or duty cycle of the pull type blower (10) by the PWM signal. The HCU (50) receives the cooling mode request from the BMS (40) for switching ON/OFF the solenoid valve (30) and a relay (14) of the rear blower (18). The BFM (60) acts as a gateway and communicates to the rear HVAC unit (20) to turn ON the compressor (120). Then the rear HVAC unit (20) communicates to the EMS to turn ON the compressor (120) after analyzing other signals like engine speed, pressure and the like and the status of the compressor (120) is communicated to the HCU (50) directly from the EMS.

In accordance with the present invention, the cooling system (100) identifies following three cooling strategies for the hybrid vehicle battery cooling namely no cooling, cabin air cooling and active cooling. Table 1 gives an overview of the component status in each of the above mentioned modes:

Table 1: Operation matrix of the cooling system (100) components
Cooling Modes The pull type blower (10)
The rear blower (8) The solenoid valve (30) The compressor (120) The front blower (108)
No Cooling OFF OFF OFF User choice User choice
Cabin Air Cooling ON ON OFF User choice User choice
Active Cooling ON ON ON ON (Override if required) ON (Override if required)

The active cooling mode
The temperature of the plurality of battery cells is continuously monitored by the BMS (40). When the cabin air temperature or an inlet air temperature of the battery (140) or the plurality of battery cells’ temperature exceeds a maximum limit (400C), the active cooling is enabled. In this mode, the rear blower (18), the pull type blower (10) and the solenoid valve (30) are turned ON. The solenoid valve (30) is switched ON to allow the refrigerant flow to the rear HVAC unit (20) so that cooled air is passed on to the battery compartment (150) for cooling. Also, the front blower (108) as well as the compressor (120) is turned ON irrespective of the driver demand. The front HVAC unit (110) is switched ON to prevent icing of an evaporative emission control system (EVAP) (not shown) and to prevent damage of the compressor (120).

The BMS (40) sends request for the active cooling to the HCU (50). On receipt of the active cooling mode request from the BMS (40), the HCU (50) turns ON the compressor (120) and the front blower (108), energizes the relay (14) of the rear blower (18) causing the rear blower (18) to run at a constant speed to deliver the required air flow rate. Also, the solenoid valve (30) is switched ON to permit the flow of refrigerant to the rear HVAC unit (20) causing the cooling of the air sucked by the rear HVAC unit (20) and pushing of the cooled air into the battery (140). The pull type blower (10) then sucks the air from the battery (140) for releasing into the atmosphere thereby reducing the temperature in the battery (140). The temperature of the air from the rear HVAC unit (20) is typically in a range of 12 0C – 16 0C that helps in bringing down the battery temperature faster.

Now referring to figure 3, a cooling architecture of the battery (140) with all the control systems and the communication strategy between the components is shown. Figure 5 gives an algorithm of the battery cooling control architecture.
Table 2 depicts signal details from the control units.

Table 2:
Sr. No. Signal Name Source Receiver Description
1 Cooling Mode The BMS (40) The HCU (50) Request (CAN)
2 Duty cycle of the pull type blower (10) The BMS (40) The HCU (50) Status (CAN)
3 The compressor (120) ON/OFF The HCU (50) The BFM (60) Request (CAN)
4 The rear HVAC unit (20) ON/OFF The HCU (50) The solenoid valve (30) Action (Hardwired)
5 Fixed speed control ON/OFF The HCU (50) The relay (14) of the rear blower (18) Action (Hardwired)
6 The rear blower (18) status The HCU (50) The BMS (40) Status (CAN)
7 The compressor (120) status The HCU (50) The BMS (40) Status (CAN)
8 The solenoid valve (30) status The HCU (50) The BMS (40) Status (CAN)
9 Cabin temperature The HCU (50) The BMS (40) Status (CAN)
10 The compressor (120) ON/OFF The BFM (60) The rear HVAC unit (20) Request (CAN)
11 Cabin temperature The BFM (60) The HCU (50) Status (CAN)
12 The compressor (120) ON/OFF The rear HVAC unit (20) The EMS Request (CAN)
13 Cabin temperature The rear HVAC unit (20) The BFM (60) Status (CAN)
14 The compressor (120) ON The EMS The compressor (120) Action (Hardwired)
15 The compressor (120) status The EMS The HCU (50) Status (CAN)

Figure 4a shows a relay circuit of the rear blower (8). An accessory relay (16) is activated by the BFM (60) and the relay (14) of the rear blower (18) is activated by the HCU (50) on a low side and hence, the rear blower (18) is switched ON. The rear blower (18) status is communicated to the rear HVAC unit (20).

Figure 4b shows a solenoid valve circuit. The HCU (50) activates the solenoid valve (30) on the low side based on the cooling mode request from the BMS (40) thereby allowing flow of the refrigerant to the rear HVAC unit (20).

The cabin air cooling mode

In this mode, the pull type blower (10) and the rear blower (18) are switched ON to suck the cabin air for cooling of the battery (140) and the solenoid valve (30) is switched OFF.

When the cabin air temperature or the inlet air temperature of the battery (140) or the plurality of battery cells’ temperature is within the maximum and minimum threshold limit (25 0C – 40 0C) and the pull type blower (10) status is ON or the duty cycle is within the limit 0-10% (TBD) then the same is communicated from the BMS (40) to the HCU (50) which in turn energizes the relay (14) of the rear blower (18) thereby runs the pull type blower (10) at a constant speed. The solenoid valve (30) is turned OFF since there is no need for active cooling, thus helps in maintaining the battery (140) temperature within the operating limit. However, the front blower (108) and the compressor (120) is turned ON/OFF based on a user requirement.

The NO cooling mode

When the maximum temperature of the plurality of battery cells is below 25 0C or the inlet air temperature is above/ below the battery cell temperature depending upon the various operating conditions, then the pull type blower (10) is switched OFF. Subsequently, the rear blower (18) is also turned OFF. During this condition the solenoid valve (30) remains closed.
The front blower (108) and the compressor (120) are turned ON/OFF based on the user requirement. However, the solenoid valve (30) remains closed. Hence, in this mode, the cabin air and the rear HVAC unit (20) air is not used for the battery cooling.

Table 3 enumerates the tasks of each control unit in various cooling modes

Table 3: Cooling Mode vs. Control Units’ Task
Control Units Cooing OFF Cabin Air Cooling Active Cooling
The BMS (40) REQUEST FOR COOLING MODE (OFF/CABIN AIR/ACTIVE)
The pull type blower (10): OFF The pull type blower (10): ON The pull type blower (10): ON
The HCU (50) No request for the compressor (120)

The rear blower (18): OFF

The solenoid valve (30): OFF

Status update No request for the compressor (120)

The rear blower (18): ON

The solenoid valve (30): OFF
Status update Request for the compressor (120)

The rear blower (18): ON

The solenoid valve (30): ON
Status update
The rear HVAC unit (20)

No special activity

No special activity Request for the compressor (120): ON
(BMS (40)--> HCU (50) --> Rear HVAC unit (20) --> EMS)

So depending upon the cooling requirement from the BMS (40), the solenoid valve (30) is actuated by the HCU (50) directly and the compressor (120) via the BFM (60) through the EMS. The compressor (120) state is communicated from the EMS to the HCU (50) directly.

Advantages of the invention
1. The BMS (40) and the HCU (50) monitor and control the temperature of the plurality of battery cells and ensure that the battery (140) is always in the operating temperature range to deliver optimum performance.
2. The cooling system (100) does not require any separate Air Handling Unit as the rear HVAC unit (20) is used to pass on the cabin temperature air / cooled air based on the operation of the solenoid valve (30).
3. The cooling system (100) utilizes the single ducting layout without any branch and flaps to pass the cabin air and the cooled air from the rear HVAC unit (20) to the battery (140) as per the requirement.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

,CLAIMS:We Claim:

1. A cooling system (100) for a battery (140) in a vehicle (200), the vehicle (200) having a front heating, ventilating, and air conditioning (HVAC) unit (110), an evaporative emission control system, an engine management system, a compressor (120), a condenser (130) and the battery (140), the front HVAC unit (110) having a front evaporator (104) and a front blower (108), the battery (140) being a high voltage battery pack having a plurality of battery cells, an inlet duct (134) and an outlet duct (138), the cooling system (100) comprising:
a pull type blower (10) packaged in an outlet side of the battery (140) to suck air therefrom for releasing in an atmosphere thereby reducing temperature in the battery (140);
a rear heating, ventilating, and air conditioning (HVAC) unit (20) being capable turning ON the compressor (120) using the engine management system, the rear HVAC unit (20) having a rear evaporator (12) and a rear blower (18);
a solenoid valve (30) to control a refrigerant flow to the rear HVAC unit (20);
a battery management system (40) adapted for controlling and monitoring temperature of the plurality of battery cells and generating corresponding request for starting a cooling mode, the cooling mode being selected from any one of an active cooling mode and a cabin air cooling mode;
a hybrid control unit (50) being capable of receiving the cooling mode request from the battery management system (40) for switching ON/OFF the solenoid valve (30) and a relay (14) of the rear blower (18); and
a body function module (60) being capable of communicating with the rear HVAC unit (20) to turn ON the compressor (120),
wherein, on receipt of the active cooling mode request from the battery management system (40), the hybrid control unit (50) turns ON the compressor (120) and the front blower (108), energizes the relay (14) of the rear blower (18) causing the rear blower (18) to run at a constant speed to deliver the required air flow rate and also, turns on the solenoid valve (30) to permit the flow of refrigerant to the rear HVAC unit (20) causing the cooling of the air sucked by the rear HVAC unit (20) and pushing of the cooled air into the battery (140) thereafter, the pull type blower (10) sucks the air therefrom for releasing into the atmosphere thereby reducing the temperature in the battery (140).

2. The cooling system (100) as claimed in claim 1, wherein the temperature of the plurality of battery cells is monitored and controlled by the battery management system (40) by controlling speed of the pull type blower (10) via a pulse width modulation signal.

3. The cooling system (100) as claimed in claim 1, wherein for the cabin air cooling mode, the pull type blower (10) and the rear blower (18) are switched ON to suck a cabin air for cooling of the battery (140) and the solenoid valve (30) is switched OFF.

4. The cooling system (100) as claimed in claim 1, wherein for passage of the cabin air and the cooled air from the rear HVAC unit (20), a single ducting layout without any branch and flaps is utilized.