FORM 2
THE PATENT ACT, 1970,
(39 OF 1970)
&
THE PATENTS RULE, 2003
COMPLETE SPECIFICATION
(SEE SECTION 10; RULE 13)
"BATTERY PACK ISOLATION SYSTEM IN ELECTRICAL AND HYBRID
ELECTRICAL VEHICLES"
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 THE MANNER IN WHICH IT IS TO BE PERFORMED

FIELD OF INVENTION:-
The present invention relates to the safety system in automobiles. More particularly, the present invention relates to a novel automobile safety system which isolates the energy storage system of the vehicle from the rest of the electrical equipments during fire or vehicle crash or vehicle immersion in water.
BACKGROUND OF THE PRESENT 1NVENTION:-
In automobiles technology, the future is about the electric and hybrid electric vehicles. These days it is very common to see many hybrid and electric vehicles on road. As the number of vehicles increases, the number of accidents on road also increases drastically. The electric vehicles are environment friendly, but at the same time electric vehicle has its own drawbacks. All the electric/hybrid vehicles are powered by an energy storage system called as battery unit. Since the electric or hybrid electric vehicles are powered by a big battery unit, in case ofan accident or if the vehicle is immersed inside the water due to a vehicle crash, there is a great chance that the battery unit will broke our fire or it may lead toelectrocution.The ultimate need is to isolate the energy storage system (aka battery pack) from the rest of the vehicle at the quickest time possible after the crash detection/water immersion so that the life of the people inside the vehicle will be saved.
Attempts have been made to isolate the battery unit of the hybrid vehicle from other high voltage electrical components by means of pyrotechnic switches. The US Patent application US2011/0304202A1 discloses system and methods for disconnection of battery power from vehicle components in an electric vehicle upon the occurrence of a crash event by means of an appropriate signal is transmitted through CAN. A Battery management unit detects the signal and then severs a power connection of vehicle, a crash event is detected and a signal to deploy an airbag or pre-tensioner is emitted. Once a decision is made to deploy the airbag, the BMU then cuts off the battery power to one or more vehicle components of electric vehicle.In this patent application the

disconnection of the HV battery during crash is done by internal BMU. The BMU gets CAN message about the crash event from an airbag ECU.
The other prior art US patent application US2008/0151454A1 discloses an electronic battery safety switch which facilitates a reliable & reversible disconnection of motor vehicle on board network from the battery. For this purpose electronic solid state switch is used which facilitates an unlimited number of switching cycles. The solid state network and the battery with application of crash signal or an over current signal or when ignition is switched off. In this concept, +12V supply line from LV battery to the starter motor, other high current drawing loads and supply line coming from alternator to +12V LV Battery are disconnected during crash event using shut off device which is integrated in the supply path. The Solid state Shut off device (not pyrotechnic switch) is triggered by dedicated controller having all other vehicle system inputs like crash status, over current flowing in path to avoid any damage to loads &LV Battery etc.,
The Japanese patent application JP03776934B2 discloses a vehicle safety device including sensing systems and safety systems which has pyrotechnic initiators. When some of the sensing systems detect a hazard for a passenger, they trigger the safety systems which in turn actuate the mechanisms. The safety device includes a processing unit connected to the sensing and safety systems via a communication interface. The processing unit analyses data signals from the sensing systems and outputs control signals to the safety systems. In this concept, +12V Supply line from LV battery to all critical loads including starter motor & other high current drawing loads disconnected during the crash event using shut off device which is integrated in the supply path. The shut off device (pyrotechnic switch) is triggered by dedicated controller having all other vehicle system inputs like crash status, over current flowing in path to avoid any damage to loads & LV Battery etc., any other abnormal activities seen in the vehicle.
In the German patent DE4406730A1, a +12V supply line from LV battery to the conventional starter motor is disconnected during the crash event using a

pyrotechnic switch which is integrated in the supply path, pyrotechnic switch is triggered by impact sensor in vehicle during the crash event.
All the attempts which are made to isolate the battery pack from the rest of the vehicle uses pyrotechnic switch or solid state switch as a key element. But most of the prior art attempts are either through CAN network or on a wireless mode and also all the attempts are made taking the Low Voltage LV load into account.
To address these drawbacks of the conventional isolation methods, there is a need in the art to provide a system which completely isolates the high voltage devices from the rest of the vehicle at the quickest time possible to save the lives of human.
OBJECTS OF THE PRESENT INVENTION:-
An object of the present invention isto isolate the battery unit of the hybrid or electric vehicle at the quickest time possible during a vehicle crash.
Another object of the present invention is to provide a simple and cost effective systemfor isolating the battery unit form the vehicle during a crash event.
STATEMENT OF INVENTION:-
Accordingly the invention provides a battery pack isolation system in electrical and hybrid electrical vehicles comprising a series of battery modules (11) packed inside a battery pack of the vehicle; a pyrotechnic switch is integrated between the battery modules inside the battery pack (10); An ECU/controller/sensor (15) communicating to the vehicle abnormal condition sensor to get the signal, Connected to the said pyrotechnic switch (12); a battery management system (13) communicating to send the signal to a pyrotechnic switch (12); the hybrid control area network (HYBRID CAN) communicating to BMS; a hybrid control unit communicating to said hybrid CAN; the vehicle CAN receiving signal from the said ECU/controller/sensor

unit communicating to the said hybrid control unit; and the arrangement is such that the said pyrotechnic switch (12) is set in such a way that on getting the abnormal condition sensor signal enables disconnection of the battery module (11) which in turn cuts off the power supply to all the high voltage devices inside the vehicle with safety feature and in case of failure to disconnect due to some malfunction of hardwired signal fails the said hybrid CAN network (14) and a vehicle can network (16) automatically takes the charge to disconnect/isolate the HV Battery pack (10) from the rest of the vehicle by communicating the said ECU/controller/sensor (15) crash active status to the BMS (13) via Hybrid Control Unit (17), where the BMS (13) will open the HV main relays.
According to another embodiment a battery pack isolation system in electrical and hybrid electrical vehicles comprising , a pyrotechnic switch, enabled from the signals received from ECU/controller/sensor abnormal sensor, is integrated into a +12V LV power supply path of the battery pack for the disconnection of the +12V power supply of the battery pack high voltage main relay's (22) (Both Positive & Negative main HV relay's will be opened) there by isolating the +12V LV power supply line to HV main relay coil power using the pyrotechnic switch at the quickest time (less than 30msec after crash event).
BRIEF DESCRIPTION OF THE FIGURES:-
The objects and advantages of the present invention will become apparent when the disclosure is read in conjunction with the following figures, wherein
Figure 1 shows a schematic diagram of the first embodiment of the present invention showing the battery isolation system with the pyrotechnic switch integrated between the modules in the battery pack;
Figure 2 shows a schematic diagram of the second embodiment of the present invention showing the battery isolation system with the pyrotechnic switch placed in the LV supply path;

Figure 3shows generalprocess logic of the HV battery isolation system with pyrotechnic switch, hard wired signals and CAN unit;
DETAILED DESCRIPTION OF THE PRESENT INVENTION:-
The foregoing objects of the 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 embodiment.
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.
In the present embodiment of the invention, there is provided a pyrotechnic switch which is integrated between the battery modules inside the battery pack enclosure with the higher IP class. When there is a crash event, the pyrotechnic switch getsthe trigger from an SRS Electronic Control Unit (also known as Air bag ECU) or from other controllers and sensors(like water sensor, gas sensor)built inside the battery pack.so that the internal battery pack high voltage busbar getsdisconnected by the pyrotechnic switch. The busbar is where modules are connected in series to form high voltage systems. This disconnection leads to the interruption of the current flow andhence isolates thebattery pack from the rest of the vehicle at the quickest time. The test data of the system shows that, isolation of battery pack from the vehicle occurs in less than 30 msec after the crash event or accident or immersion.
The High Voltage (HV) battery pack system of the present invention typically consists of modules which are cells connected either in series or parallel to meet the system energy and power requirements, a battery management system (BMS) which is used for effective function of the HV battery to ensure its full functionality which will be delivered, by conspiring reliability and safety requirements, a battery disconnect unit (BDU) where in the HV main relays, Pre

charge relays, Pre chare resistor, HV fuse, HV current sensor are integrated into a single unit. The modules are interconnected using bus bars internally in the HV Battery pack.
According to figure 1 of the present invention, there is provided a series of modules (11) which are packed inside abattery pack of the vehicle. Within the battery pack (10), the battery management system (13) is also placed which sends the signal to a pyrotechnic switch (12). In this first embodiment of the present invention, the pyrotechnic switch is integrated between the battery modules inside the battery pack(10). An SRS/Air bag ECU (15) gets the signal from the vehicle crash sensor (not shown). This signal regarding the crash event will in turn be sent to the pyrotechnic switch (12) present inside the battery pack (10) which is connected between the battery modules (11). When the pyrotechnic switch (12) gets the crash signal, it suddenly disconnects the battery module (11) which in turn cuts off the power supply to all the high voltage devices inside the vehicle. Due to some malfunction, if the above hardwired signal fails to do the intended work, ahybrid CAN network (14) and a vehicle can network (16) automatically takes the charge and it disconnects/isolates the HV Battery pack (10) from the rest of the vehicle by communicating the SRS (15) crash active status to the BMS (13) via Hybrid Control Unit (17), where the BMS (13) will open the HV main relays.Above objective can be realized by SRS (Airbag control unit) during crash event, SRS ECU gives the hardwired trigger signal to the pyrotechnic switch which disconnects the HV battery system from the rest of the vehicle by disconnecting the modules internal bus bar connection.
Referring to figure 1, a battery pack isolation system in electrical and hybrid electrical vehicles comprises a series of battery modules (11) packed inside a battery pack of the vehicle. A pyrotechnic switch is integrated between the battery modules inside the battery pack (10). An ECU/controller/sensor (15, communicating to the vehicle abnormal condition sensor to get the signal, Connected to the said pyrotechnic switch (12); a battery management system (13) communicating to send the signal to a pyrotechnic switch (12). The hybrid control area network (HYBRID CAN) communicating to BMS. A hybrid

control unit communicating to said hybrid CAN. The vehicle CAN receiving signal from the said ECU/controller/sensor unit communicating to the said hybrid control unit. And the arrangement is such that the said pyrotechnic switch (12) is set in such a way that on getting the abnormal condition sensor signal enables disconnection of the battery module (11) which in turn cuts off the power supply to all the high voltage devices inside the vehicle with safety feature and in case of failure to disconnect due to some malfunction of hardwired signal fails the said hybrid CAN network (14) and a vehicle can network (16) automatically takes the charge to disconnect/isolate the HV Battery pack (10) from the rest of the vehicle by communicating the said ECU/controller/sensor (15) crash active status to the BMS (13) via Hybrid Control Unit (17), where the BMS (13) will open the HV main relays.
According to the second embodiment of the present invention as shown in figure 2, apyrotechnic switch is integrated into a +12V LV power supply path of the battery pack. The preferred location for this pyrotechnic switch would be in the vehicle fuse box/BEC/LV architecture (25). When there is a crash event, the pyrotechnic switch (23) getsthe trigger from an SRS ECU (24) or from other controllers cum sensors like water sensor, hydrogen (gas) sensor inbuilt inside the battery pack. This leads to the disconnection of the +12V power supply of the battery pack high voltage main relay's (22) (Both Positive & Negative main HV relay's will be opened) there by isolating the+12V LV power supply line to HV main relay coil power using the pyrotechnic switch at the quickest time (less than 30msec after crash event).
The electrical disconnect mechanism is a combination of an automatic circuit breaker, an electrical relay and a manual switch which will be integrated inside the battery pack.
Referring to figure 3 of the present invention, it shows the process flow of the battery isolation mechanism wherein the Hybrid Control Unit sends the signal to BMS which in turn triggers the pyrotechnic switch. The SRS ECU (32) sends the status of crash to the pyrotechnic switch (33). The Hybrid Can Unit (30) sends the status of the crash signal and if the crash active status is equal to 1,

it shows the occurrence of crash. This crash status signal sets the BMS (31) to open the main HV relays and hence isolates the battery from the rest of the vehicle electrical equipments.
During vehicle crash conditions, when the +12V power supply of HV relays is disconnected by the pyrotechnic switch, where there is high current flowing HV relays to loads ,there is chance for the HV relays to be physically welded. This condition fails to meet the intended purpose of using the pyrotechnic switch for HV crash safety.To solve the above problem a lot of clamp open test on the HV relays are conducted. The HV relays are opened at different load currents (e.g. 250A, 200A) and the same was checked for any physical welding condition. The HV relays were selected based on the testing results.
During other abnormal conditions like water entry into passenger compartment, fire or smoke in the vehicle, the BMS detects and sends the hardwired trigger signal to the pyrotechnic switch to disconnect HV Battery system from the rest of the vehicle by disconnecting modules internal bus bar connection based on the input from dedicated sensors for detecting water and fire (H2O sensor, smoke sensor set inside the HV battery pack). The technical advantages achieved by the present invention are:
- Normally CAN communication from the SRS/Airbag ECU is used to inform the crash event status to the BMS and other control units in the vehicle to initiate the crash emergency shutdown sequence. However, CAN has its own latency and de-bounce time apart from the SRS ECU will be there in different CAN channel. SRS will send crash status to HCU and then the HCU sends the information regarding crash status to the BMS and MCU.
- Normally the mechanical service disconnect mechanism is present in the HV battery which will be used for isolating the HV Battery during servicing period of HV systems. When there is any above abnormal situation, this service disconnect mechanism will not serve this purpose, butthe second embodiment of the present invention can fulfillthe above requirement by disconnecting the HV current path, This pyrotechnic switch is triggered from

the crash sensor interface with SRS ECU, based on the sensors like hydrogen gas sensor & water sensor interface with Battery management system.
- Isolatingthe HV Battery was time critical safety requirement and the same was achieved with the help of SRS hardwired signal to trigger pyrotechnic switch at the quickest time.
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 invention. Also, the terminologies used herein are for the purpose of description and should not be regarded as limiting.

WE CLAIM:-
1. A battery pack isolation system in electrical and hybrid electrical vehicles comprising a series of battery modules (11) packed inside a battery pack of the vehicle; a pyrotechnic switch is integrated between the battery modules inside the battery pack (10); An ECU/controller/sensor (15, communicating to the vehicle abnormal condition sensor to get the signal, Connected to the said pyrotechnic switch (12); a battery management system (13) communicating to send the signal to a pyrotechnic switch (12);the hybrid control area network (HYBRID CAN) communicating to BMS; a hybrid control unit communicating to said hybrid CAN;the vehicle CAN receiving signal from the said ECU/controller/sensor unit communicating to the said hybrid control unit; and the arrangement is such that the said pyrotechnic switch (12) is set in such a way that on getting the abnormal condition sensor signal enables disconnection of the battery module (11) which in turn cuts off the power supply to all the high voltage devices inside the vehicle with safety feature and in case of failure to disconnect due to some malfunction of hardwired signal failsthe said hybrid CAN network (14) and a vehicle can network (16) automatically takes the charge to disconnect/isolate the HV Battery pack (10) from the rest of the vehicle by communicating the said ECU/controller/sensor (15) crash active status to the BMS (13) via Hybrid Control Unit (17), where the BMS (13) will open the HV main relays.
2. A battery pack isolation system in electrical and hybrid electrical vehicles comprising , a pyrotechnic switch, enabled from the signals received from abnormal sensor, is integrated into a +12V LV power supply path of the battery pack for the disconnection of the +12V power supply of the battery pack high voltage main relay's (22) (Both Positive & Negative main HV relay's will be opened) there by isolating the +12V LV power supply line to HV main relay coil power using the pyrotechnic switch at the quickest time (less than 30msec after crash event).

3. The battery pack isoation system as claimedin claim 2 wherein preferred location of the said pyrotechnic switch is in the vehicle fuse box/BEC/LV architecture (25).
4. The battery pack isolation system as claimed in claim 1 to3 wherein the said Electronic Control Unit is SRS ECU(also known as Air bag ECU)
5. The battery isolation systemas claimed in claims 1 to 3 wherein the said controller/ sensor is other controllers and sensors like water sensor, gas sensor.
6. The battery pack isolation system as claimed in claims 1 to 4 wherein the said abnormal condition sensor is crash/water/gas sensor