FORM 2
THE PATENTS ACT 1970
(39 of 1970) &
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See Section 10; rule 13)
TITLE OF THE INVENTION
A System and method for Detecting Exterior Lights switch failure and Controlling
Exterior Lights
APPLICANT
TATA MOTORS LIMITED, an Indian company having its registered office at Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001 Maharashtra, India
INVENTORS
Gurneet Singh, Anil P Joshi Both Indian nationals of TATA MOTORS LIMITED, an Indian company having its registered office at Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001 Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in
which it is to be performed.
Field of Invention:
The invention relates to operation of Exterior Lights of the vehicle in case, if switch get disconnected or burned out, which is providing respective inputs to control device.
Background of invention:
In current vehicle architecture, parking Lamps and Dip Beam/ Low Beam outputs are driven through Control device, depending on the combination of Parking Light switch and Head lamp Switch Inputs along with Ignition state of the vehicle. If Parking Input is present Control Device makes Parking output ON, If Head Lamp Switch is ON and vehicle state is OFF (Ignition OFF), Control Device will keep Parking output ON. If Head Lamp Switch is ON and vehicle state is Ignition, Dip Beam/ Low Beam is turned ON along with Parking Lamps. High Beam/ Main Beam can be selected by combination switch which can be direct input to control device or directly controlled through combination switch, which depends on the vehicle architecture. Parking Lamps and Dip Beam/ Low Beam outputs are also made ON as a part of Follow Me Function and Approach Light Function so inputs and outputs are routed via control device for whole operation.
It was observed that switch providing Inputs to Control Device may get disconnected or burned due to high current surges or transients. This results into complete loss of exterior lighting even at the time of driving, which can cause accidents.
Summary of the Invention:
The idea behind the invention is to add redundancy in conventional switch operation, especially in case of failures of switches. Motive is achieved by monitoring OFF position of the light control switch. If switch is in healthy condition, it will be providing at least one input at a time to Control Device. If switch get burned / disconnected Control Device will not get any Input from switch. Under such circumstances if vehicle state is Ignition control device will keep Exterior Lights ON, until vehicle state is changed to OFF or input from switch is get restored. Diagnostic Trouble code can also be logged for the same, so that service person can come to know about the failure related information.
According to the present invention a system for detecting exterior lights switch failure and controlling exterior lights for a vehicle comprising; at least one exterior light of said vehicle; a switching device having plurality of selectable positions with at least one selectable exterior lights OFF position; an input of either ON or OFF from the ignition key system of said vehicle and a controller for activating (ON) or deactivating (OFF) at least one exterior lights based on the presence or absence of input from said switching device and/or said ignition key input.
Another aspect of the invention is to provide a method for detecting exterior lights switch failure and controlling exterior lights for a vehicle comprising; checking position input signal from a switching device having plurality of selectable positions; receiving ON or OFF state signals from ignition key system of said vehicle; activating (ON) or deactivating (OFF) vehicle exterior lights based on the presence or absence of position input signal from the switching device and/or state signals from the ignition key.
Brief description of the drawings:
Figure 1 shows the Block Diagram of Switch Inputs and Outputs through Control Device Figure 2 shows the flow chart for the algorithm adopted for controlling exterior lights incase of switch failure.
Detailed description of drawings:
In Conventional vehicle architecture only two inputs are given to Control device i.e. Parking Position Input and Head Lamp Position Input. As per the present invention, to add redundancy in switch operation for safety critical concerns one more input is added which updates control device about it's OFF position.
Referring to the figure 1, the block diagram shows the switch inputs and outputs through a control device. Three inputs "OFF position", "Parking position" and "Head Lamp Position" is taken as input to the controller. Depends on the position of the switch controller decides the operation of the exterior lights in ON or OFF. Normal Operation:
When Parking Light Switch Input is made ON. i.e. Parking Position input is available to Control Device; Control device will turn ON Parking/Side Lights Relay to make Parking
Lamps ON. This operation is independent of state of vehicle (whether vehicle state is Ignition or OFF). If switch is turned to Head Lamp position but vehicle state remain unchanged (OFF), Control device will keep Parking/ Side Lights Relay ON. If Vehicle state is changed to Ignition, Control device will turn Dip Beam/ Low Beam relay ON. When switch is turned to OFF Position Parking/ Side lights relay and Dip Beam/ Low Beam relay will be turned OFF by monitoring OFF position Input.
Failure Case Operation:
Switch may get fail or disconnected at any of the possible positions i.e. OFF, Parking or Head Lamp. If Vehicle state is Ignition and Switch is not providing any input to control device, control device will turn Exterior Lights - Parking/Side Light Relay and Dip Beam/ Low Beam relay ON, if these relays are not previously ON. If they are already ON and vehicle state is Ignition, control device will keep it ON. If Input from switch is restored control device will execute normal operation, according to present input. If Input from switch is missing and vehicle state is changed from Ignition to OFF, Exterior Lights- Parking/ Side Light Relay and Dip Beam/ Low Beam Relay will be turned OFF.
Referring to figure 2, the Flow chart depicts the algorithm adopted to control the exterior lights in normal working condition and in switch failure mode.
Initial state is set to default OFF for all exterior lights output. All Inputs are scanned for decisions to be taken, as mentioned below-
1. If OFF position Input is available to control device Exterior Lights- Parking/ Side Light Relay and Dip Beam/ Low Beam relay are made/ kept OFF.
2. If None of the Inputs (OFF position, parking Position, Head Lamp Position) available to control device and vehicle state is Ignition then the Parking /Side Light Relay and Dip Beam /Low Beam relays are turned ON.
3. If vehicle state changes to OFF, i.e. Ignition is turned OFF; both exterior lights outputs will be turned OFF.
4. If any of the three inputs available, control device checks for the corresponding input to take the decision.
5. If parking input or Head Lamp input is present Parking/ Side Light Relay is made ON.
6. If Head Lamp Input is present and vehicle state is Ignition Dip Beam/ Low Beam Relay is turned ON.
7. If input from switch changed/ lost Loops monitor the changes and switch to new decision according to available input, as described above.
Advantages:
Availability of Exterior Lights (Partial), even if switch get burned or disconnected, This might be advantageous as a safety critical concern, if switch get fail during drive; vehicle will not result into complete loss of Exterior Lights Operation. If Vehicle state is Ignition and No input is available to Control Device, Exterior Lights will be turned ON, as an indication to driver that Light switch is Faulty.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.
We claim
1) A system for detecting Exterior Lights switch failure and controlling exterior lights for a vehicle comprising; at least one exterior light of said vehicle; a switching device having plurality of selectable positions with at least one selectable exterior light/s OFF position; an ignition key system for giving input of either ON or OFF state and a controller for activating (ON) or deactivating (OFF) said exterior light's based on the presence or absence of input from said switching device and/or based on said ignition key input.
2) A system for detecting exterior lights switch failure and controlling exterior lights for a vehicle as claimed in claim 1 wherein said controller activate or deactivate the exterior light/s to continue in OFF state in the absence of input from said switching device and said ignition input is OFF.
3) A system for detecting exterior lights switch failure and controlling exterior lights for a vehicle as claimed in claim 1 wherein said controller activate the exterior light/s in the absence of input from said switching device and said ignition input is ON.
4) A system for detecting exterior lights switch failure and controlling exterior lights for a vehicle as claimed in claim 1 wherein said controller activate or deactivate the exterior light/s based on the position input from said switching device.
5) A method for detecting exterior lights switch failure and controlling exterior lights for a vehicle comprising; checking position input signal by a controller from a switching device having plurality of selectable positions for said exterior lights; receiving ON or OFF state signals from a ignition key system of the vehicle by said controller; activating (ON) or deactivating (OFF) vehicle exterior lights based on the presence or absence of position input signal from the switching device and/or state signals from the ignition key system by said controller.
6) A method for detecting exterior lights switch failure and controlling exterior lights for a vehicle as claimed in claim 5 wherein said controller activating or deactivating the exterior light/s to continue in OFF state in the absence of input from said switching device and said ignition input is OFF.
7) A method for detecting exterior lights switch failure and controlling exterior lights for a vehicle as claimed in claim 5 wherein said controller activating the exterior
light/s in the absence of input from said switching device and said ignition input is ON.
8) A method for detecting exterior lights switch failure and controlling exterior lights for a vehicle as claimed in claim 5 wherein said controller activating or deactivating said exterior light/s based on the position input from said switching device.
9) A system and method for detecting exterior lights switch failure and controlling exterior lights for a vehicle as described above with reference to the accompanying drawings.