FORM 2
THE PATENT ACT, 1970
(39 OF 1970)
&
THE PATENTS RULE, 2003
COMPLTE SPECIFICATION
(SEE SECTION 10; RULE 13)
"BATTERY COMPARTMENT COOLING SYSTEM IN HYBRID VEHICLE"
MAHINDRA & MAHINDRA LIMITED
AN INDIAN COMPANY,
R&D CENTER, AUTOMOTIVE SECTOR,
89, M.I.D.C, SATPUR,
NASHIK-422 007,
MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE NATURE OF THE INVENTION AND MANNER IN WHICH IT IS TO BE
PERFORMED

FIELD OF THE INVENTION:-
The present invention is related to hybrid vehicle wherein the main source of power is battery. More particularly the present invention is related to the battery compartment cooling system in hybrid vehicle wherein the cab air and air from the air conditioner duct is judiciously utilized.
BACKGROUND OF THE PRESENT INVENTION:-
The Battery used in Hybrid vehicles needs to be maintained within the temperature range of 25°C to 40°C. At times of peak load, batteries must generate a high output within a very short time, causing significant warming of the Li-ion cells due to internal resistance. Coupled with the fact that, in the warmer weather and in warmer climates in particular, the temperature of the vehicle interior can rise to well in excess of 40°C, operation of Li-ion batteries without cooling is not an option. To address this concern, a variety of solutions is available in public domain with varying degree of success.
Patent document No. US20060080986 discloses battery cooling device wherein air suction mode can be switched among the inside air mode in which the air sucked by the battery cooling blower to cool the battery for the vehicle use is the air inside a vehicle passenger compartment, the outside air mode in which the air sucked by the battery cooling blower is the air outside the vehicle passenger compartment and the cooling air mode which in which the air sucked by the battery cooling blower is the air cooled by an evaporator of the rear seat side air conditioner. But this system has some drawbacks as follows:
It uses a push type blower which gives less uniform airflow and less efficient cooling of the battery comparing to pull type blower. Also, this is a bulky system that involves complex logic and requires more packaging space. Cost of this system is also comparatively high.

Another patent application No. US20110269387 describes air based hybrid battery thermal conditioning system wherein at least one auxiliary air source has a selectively operable actuator door which either connects or disconnects the auxiliary air source to the energy storage system blower, the air flow being selected to optimally temperature condition the energy storage system. The auxiliary air source preferably includes the HVAC ducting. But this system has some drawbacks as follows:
This system utilizes air from the front HVAC unit that serves for Cabin cooling. Hence, when there is more demand from the battery for cooling, more air from the front HVAC system is diverted for Battery which may cause discomfort to the passengers. Also, the blower used is a push type blower which does not ensure uniform and efficient cooling of the battery.
The present invention is focused on a battery cooling mechanism using a bi-level duct which has two branches which works in tandem according to the temperature of the battery cooling unit. Further, the invention is technically advanced as it takes care of the drawbacks of prior art concepts as mentioned above.
OBJECTIVES OF THE PRESENT INVENTION:-
The main object of the present invention is to provide a battery pack cooling system for the hybrid vehicles.
Another object of the present invention is to provide a battery pack cooling system using a bi-level duct for the hybrid vehicles.
Another object of the present invention is to provide a battery pack cooling system for the hybrid vehicles which works in tandem according to the temperature of the battery unit.

Still another object of the present invention is to provide a battery pack cooling system using a bi-level duct that eliminates a separate AHU thereby saving the cost and weight.
Still further object of the present invention is to provide a battery pack cooling system using a bi-level duct that optimizes the space requirement thus making the system simpler and compact.
STATEMENT OFINVENTION:-
Accordingly the invention provides a battery compartment cooling system in hybrid vehicle comprises an air conditioner for the said vehicle cabin cooling; a battery compartment equipped with a hybrid control unit provided with air duct having branched bi-level ducts, one of the said duct leading to the vehicle cabin and the second duct leading to the said air conditioner rear duct; a flap is provided at the joint of the said branched bi-level ducts so as to keep the said second duct passage closed normally; an actuator provided in the said branched joint for operating the said flap to rotate to an angle so as to open the passage of the said second duct after signal from the said hybrid control unit; a blower of pull type placed behind the said battery compartment for sucking air; a temperature sensor communicating with the said hybrid control unit for controlling the signal out put provided in the said battery compartment.
BRIEF DESCRIPTION OF THE FIGURES:-
The objectives and technical advantages of the present invention will become apparent when the disclosure is read in conjunction with the following figures, of accompanying drawing wherein
Figure 1 shows the underbody layout of the vehicle comprising the battery compartment and routing of cooling ducts with vehicle body shell, in accordance with the present invention.

Figure 2 shows the battery compartment cooling system ducts from underbody without Vehicle bottom shell.
Figure 3 shows the isometric layout of battery compartment cooling system components in accordance with the present invention.
Figure 4 shows the block diagram of the system wherein only cab air is used for cooling the battery compartment.
Figure 5 shows the block diagram of the system wherein air from rear duce of air-conditioner is used for cooling the battery compartment.
Figure 6 shows the flowchart explaining the working of the system in accordance with the present invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION:-
Referring to Figures 1 & 2, battery compartment cooling system (1) in accordance with the present invention comprises of battery compartment (2), bi-level ducts (3, 4), blower (5) and flap actuator (6). The bi-level ducts (3, 4) have a flap (7) at the intersection of duct (3) and duct (4). The blower (5) in the system is the pull type blower and placed innovatively behind the battery compartment (2) in such manner that when it pulls the air from the bi-level duct, the battery compartment area gets covered by the waves of cooling air, thus ensuring the cooling of the battery compartment. The bi-level duct is routed from the battery compartment (2) and has two branches as duct (3) and duct (4). The duct (3) is for sucking the cabin air and the other duct (4) is connected to the rear air-conditioner (8) inside the vehicle, thus forming the rear air-conditioner duct. Inside this duct, there is a built in flap (7) that is controlled by an actuator (6) which receives signal from the hybrid control unit (HCU) of the vehicle. The actuator (6) which controls the flap is placed inside the duct assembly at the portion where the ducts from cabin air and Rear A/C air joins whereas hybrid control unit is part of the Battery compartment itself.

The Hybrid control unit is connected with the actuator through the vehicle wiring harness. Signal from this unit will be sent as voltage to the actuator motor when required, which in turn will rotate the flap through the desired angle. The duct (3) and duct (4) communicates with each other and gets opened in the battery compartment unit (2) as shown in figure 1.
Referring to Figure 3, during normal operating conditions of the vehicle, the conditioned air present inside the vehicle cabin is sufficient to cool the Battery compartment. In this situation, actuator (6) moves the flap (7) and blocks the duct (4) thus restricting the entry of air flow from the air-conditioner (8). The duct (3) forms the seamless passage of cooling air from the vehicle cab to battery compartment.
Referring to figure 4, at the times, during soaking, charging of the battery, etc., the temperature inside the Battery compartment may rise more than 40°C. Under these circumstances, much cooler air is needed, which is taken from the rear air-conditioner duct of the vehicle. In this situation, actuator (6) moves the flap (7) and blocks the duct (3) thus restricting the entry of air flow from the vehicle cab. The duct (4) forms the seamless passage of cooling air from the air-conditioner duct to battery compartment.
During normal position of the flap (7) inside the duct will be such that, it directs the cabin air to the battery compartment (2). if the temperature inside battery compartment increases in spite of the cabin air cooling, it will be sensed by the BMS (Battery management system) and the information will be passed on to the HCU, which in turn will send signal to the actuator. Once the actuator receives the signal, it will control the flap such that it directs the air from Rear A/C (8) into battery compartment and blocks the cabin air passage.
The BMS continuously monitors the temperature inside the battery compartment with a temperature sensor and this sensor keeps sending input {in terms of resistance) to the Hybrid control unit. When the temperature of the Battery compartment raises above 40°C, the Hybrid control unit is alerted based on the sensor input and hence sends signal in terms of calibrated

voltage to the actuator, through the wiring harness. Once the actuator receives the voltage signal from HCU, it will move the flap through the set angle to allow the cooled air from rear AC towards the battery compartment. Similarly, when the temperature of the battery compartment comes down below
40°C, the Hybrid control unit is alerted based on the temperature sensor input. Now, the voltage signal sent to the actuator will be such that the actuator moves the flap to allow cabin air towards battery compartment.
The advantages achieved by the present invention are as under:
- The invention eliminates the use of separate AHU thereby saving the space, cost and weight. Reduction in weight of at least 2 kg and cost can be reduced to approx. 50% by eliminating a separate AHU.
- The invention provides much compact and simpler battery compartment cooling system.
- The invention ensures uniform and efficient air flow across the battery compartment because of the pull type blower used in the system.
It should be understood that the present invention is not to be limited by the exact details of the illustrated embodiment. However, it is to be taken as the preferred example of the invention and that various changes may be resorted to by a person skilled in the art without departing from the spirit of the description and should not be regarded as limiting.

WE CLAIM:-
1. A battery compartment cooling system in hybrid vehicle comprises an air conditioner for the said vehicle cabin cooling; a battery compartment equipped with a hybrid control unit provided with air duct having branched bi-level ducts, one of the said duct leading to the vehicle cabin and the second duct leading to the said air conditioner rear duct; a flap is provided at the joint of the said branched bi-level ducts so as to keep the said second duct passage closed normally; an actuator provided in the said branched joint for operating the said flap to rotate to an angle so as to open the passage of the said second duct after signal from the said hybrid control unit; a blower of pull type placed behind the said battery compartment for sucking air; a temperature sensor communicating with the said hybrid control unit for controlling the signal out put provided in the said battery compartment.
2. The cooling system as claimed in claim 1 wherein the hybrid control unit connected with the actuator through the vehicle wiring harness to send signal as voltage to the actuator motor when temperature sensor senses increase in battery temperature.
3. The cooling system as claimed in claim 1 wherein the signal out put of the said hybrid control unit in the form of voltage for rotating actuator motor for turning the said flap at desired angle.