FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patent Rules, 2003
Provisional Specification
(See section 10 and rule 13)
A novel system to automatically stop and start automobile engines
Mahindra and Mahindra Limited
An Indian company registered under the Companies Act, 1956
Automotive Sector, R&D Center, 89 MIDC, Satpur, Nashik 422 007,
Maharashtra State, India.
The following specification describes the invention:

A novel system to automatically stop and start automobile engines
Field of the Invention
The present invention generally relates to automobile engines. In particular, the invention relates to a system to automatic stop and start of the engines of motor vehicles.
Background and Prior Art Search
Vehicle stoppages at traffic signals or in traffic jam are common all over the world. Most of the vehicles caught in traffic jams or stopped at traffic signals generally have their engines running throughout the stoppage and continue to consume fuel and release emissions to the atmosphere. This leads to fuel wastage and damage to environment.
Drivers could stop engines in situations where running of engines is wasteful and environmentally damaging, however, most drivers either do not remember to do so or do not attribute sufficient importance to the fuel-wastage and environmental-damage aspects to take the requisite actions. Even if a driver wishes to turn off the engine under certain conditions, he would be reluctant to do so in case such conditions occur frequently, for example stoppages at a number of signals during


a relatively short journey. It would therefore be extremely useful to have system that automatically stops and starts engines upon meeting of certain conditions.
Several systems are available that automatically, that is without turning of the ignition key, stop engines when certain other conditions are met. Such systems generally employ sensors to detect presence of certain conditions. Signals are fed to a control unit, which then acts to stop the engine as appropriate. Typically such systems detect conditions such as engines idling for some time, vehicles moving at a very slow speed for a period, and so on, as triggers to automatic stopping of engines.
The engines are normally automatically restarted based on another signal from the driver such as release of the brake pedal, operation of the clutch pedal, or release of the hand brake, along with a set of other predefined states/conditions such as gear shift lever being in the neutral position. These conditions normally represent situations where the driver of a stationary vehicle wants to move the vehicle.
US patent No. 4414937 discloses an automatic engine stop and start apparatus for automatically stopping and starting an engine. Away from monitoring of the usual conditions like engine idle speed, gear shift lever position etc., this system produces a means of warning to the user when a critical condition is detected by a set of pre-defined states. When a car starts to move while the engine has been
automatically stopped and the car is to be braked and a car velocity exceeds a


predetermined speed and a booster pressure of a brake falls below a predetermined level, the apparatus issues an alarm. To this end, the apparatus includes a car velocity sensor for detecting the car velocity, a slope sensor for detecting the necessity of the brakes for the car, a negative pressure switch for detecting the booster pressure of the brake and alarm means responsive to detection outputs of those sensors.
US patent No. 4454843 describes automatic engine stop and start system including the effect of engine coolant temperature. Determination as to whether the condition of automatically stopping an engine is formed or not is made based on outputs from pluralities of sensors and switches for detecting the operating conditions of various portions of a vehicle such as clutch pedal position, accelerator pedal position, vehicle speed, defogger switch and Head lamp switch. Even if the result of determination satisfied the conditions of automatic stop, automatic stoppage is not effected when the temperature of the engine cooling water exceeds predetermined temperature limit.
US patent No. 5653659 discloses an automatic engine stop-start system that automatically stops an engine to reduce the fuel consumption whenever a predetermined conditions such as vehicle speed, engine speed , neutral position, clutch position, brake chamber pressure are fulfilled and automatically starts the engine whenever another predetermined conditions such as clutch position, engine
speed & neutral position are fulfilled. This system is particularly arranged to


detect gearshift lever position of an automatic transmission to determine various automatic stop/start conditions so that an engine in a car with an automatic transmission can be automatically stopped/started.
One of the drawbacks of the currently available automatic engines stop-start systems is that they do not use certain important features as trigger for automatic engine stop or start. For example, occurrence of rain, and the vehicle entering a tunnel are important situations where an auto stop-start system that bypasses itself would be of great use. Similarly, particularly in a country like India, the drivers caught in a traffic jam blow their horns as a 'heads up' for the vehicle in front of them. In such situation a system that uses purposeful blowing of the horn as a trigger to reset the auto stop feature of the system is considered to be of great practical use.
One other drawback of the currently available automatic engines stop-start systems is that they do not consider the state of the vehicle battery in the process of automatically stopping or starting the engine. The cranking of the engine uses significant battery resources. Existing auto stop-start systems monitor the battery voltage only momentarily and not over a sufficiently long period. An auto stop-start system for an engine that does not consider the state of the battery could potentially cause damage to the battery and reduce its running life.


A further drawback of the currently available automatic engines stop-start systems is that they do not have a provision for a 'warm-up' period for the engine before the auto stop-start system kicks in. This leads to reduced efficiency of the engine in terms of fuel usage and emissions and overall reduction of engine life. Some of the existing systems use engine coolant temperature as an indicator of a 'warmed-up' engine. However, this is not a satisfactory indicator as there's not an established calibration between coolant temperature and the state of lubrication of the engine and also the temperature of the catalytic converter.
Another important drawback of the currently available automatic engines stop-start systems is that they do not provide the driver of the vehicle with the updates on the healthiness and functioning state of the stop-start system. In this respect, the driver has no reliable means to know whether a malfunction in some part of the auto stop-start system has occurred. It would be of great use if a system to diagnose and pinpoint the root cause of the malfunction were to be provided.
There is also no provision to enter into diagnostic mode to detect which component of the stop start system has failed. Also, in the existing systems, if there is any fault in the engine other than the starting system, the starter motor keeps attempting to crank the engine continuously which may spoil the starter motor and battery as well.


Therefore there is a need to provide a system for automatically stopping and starting the engine when certain conditions are met. In particular, there's a need to provide a system that assesses whether a predefined set of conditions has been met and either starts or stops the engine as appropriate. The need also exists for an auto stop-start system that takes cognisance of factors such as the vehicle speed, engine speed; positions of the bonnet, the clutch pedal and the gearshift lever; levels of the ambient light intensity and of the battery voltage during normal operation and during cranking; operation of the horn and the occurrence of rain.
There is also a need to provide an auto stop-start system that indicates to the driver by the way of an indicator that at least one part of the system itself is malfunctioning. There is a further need provide a system that allows the driver to bypass the auto stop-start system. At the same time, a need exists for an auto stop-start system that bypasses itself automatically under certain special circumstances.
Objects of the Present Invention
Accordingly, the major objects of the auto stop-start system of the present
invention are:
1. To automatically stop/start the engine based on certain predefined conditions that represent aspects such as the vehicle speed, engine speed, positions of the bonnet, the clutch pedal and the gearshift lever, levels of the ambient light intensity and that of the battery voltage during normal operation and during cranking, operation of the horn, occurrence of rain.


2. To provide an auto stop-start system that indicates to the driver by the way of an indicator that at least one part of the system itself is malfunctioning.
3. To provide a system that allows the driver to bypass the auto stop-start system, but which bypasses itself under certain special circumstances.
4. To provide an auto stop-start system wherein it is easily possible to identify the root cause of its malfunctioning.
5. To provide an auto stop-start system which does not automatically stop the engine during a predefined warm up period after every ignition start.
Advantages of Present Invention
While achieving the above objects, the invention offers many advantages over the auto stop/start systems that are available currently to automatically stop and start engines. These are:
• Improved Mileage - Since the engine switches off during idling, fuel is saved which consequently leads to increase in mileage.
• Reduced Emission - Since the engine switches off during idling, there is no emission released during this period and hence leads to the reduced emission & cleaner atmosphere.
• Ease of Start
• Less Noise at Traffic Signals & Jams
• Safety when bonnet is open
• Easy Diagnosis if any malfunction occurs through error code generation

• Preservation of Battery
• Customisation by USER
• Status indication to the user
• Starter Motor Protection
• Avoidance of stop during rain and thus avoid subsequent cold crank conditions
• Avoidance of stop in tunnels
Description of figures:
For better understanding of the description of the present invention, drawings are
enclosed.
Figure 1 shows the schematic view of the auto stop start system
Figure 2 shows schematic view of neutral switch assembly
Figure 3 shows the flow-chart of the overall operation of the auto stop-start system
Figure 4 shows the flow-chart of the of stop request creation
Figure 5 shows the flow-chart of the start request creation
Figure 6 shows the flow-chart of the system status indication and automatic selection of the system bypass mode
Figure 7 shows the flow-chart of battery and starter motor protection Figure 8 shows the flow-chart of entry into diagnostic mode
Figure 9 shows sample fault-detection codes in diagnostic mode


Summary of Present Invention
The present invention describes a system for automatically stopping and starting the engine, hereafter referred to as the auto stop-start system. The system comprises a control unit that receives signals from various units of an automobile vehicle. The control unit assesses whether a predefined set of conditions has been met and either starts or stops the engine as appropriate. The predetermined conditions are based on the factors that include the vehicle speed, engine speed, positions of the bonnet, the clutch pedal and the gearshift lever, levels of the ambient light intensity and that of the battery voltage during normal operation and during cranking, operation of the horn, occurrence of rain. The invention also includes a system whereby the driver is notified by the way of an indicator that at least one part of the auto stop-start system is malfunctioning. The driver has the option to use this information to bypass the auto stop-start system. The auto stop-start system of the present system has the facility whereby it is possible to identify the root cause of any malfunctioning of the system.
The inventions also offers the option for the driver of the vehicle to bypass the auto stop-start system. On the other hand, the auto stop-start system automatically bypasses itself under certain special circumstances.
The engine is Stopped automatically if all the following states/conditions are true


(see Figure 4)
• Initial warm up period after first start through ignition key for predefined time duration (For Example - 3 minutes) is completed.
• Battery Voltage did not fall below specified threshold value (for example - 8.5 volts) during previous cranking.
• No Malfunction of the components involved in the system is detected
• Below set of states/conditions exists true for a predefined time duration
o The engine RPM lies around a predefined idling range (For example - 800±50 rpm)
o Clutch Pedal is Not Pressed to the level of 90%
o Vehicle Speed is close to zero
o Gear shift lever in Neutral position
o Online Battery Voltage does not lies continuously below than stipulated value(For example < 12. 6 volfjfor a predefined duration (For example - 2 seconds)
o Mode Selection Switch in appropriate position (Position 2 or Position 3)
o Bonnet remains closed
o Doors remains closed
o No operation of horn
o No occurrence of rain
o No entry of vehicle into tunnel during day time


The engine is started automatically if the following states/conditions are true, (see Figure 5)
• Clutch Pedal is Pressed to minimum 90 %
• Engine Speed is close to zero
• Gear shift lever in Neutral position
• Bonnet remains closed
• Doors remains closed
• Mode Selection Switch in the appropriate position (1 , 2 or 3)
• No Malfunction of the components involved in the system is detected
• Seat belt is worn by the user.
Detailed Description of the Present Invention
As shown in Figure 1, automatic engine stop-start system of the present invention comprises an engine stop-start control unit, referred to as the control unit; a signal receiver, into which signals from various systems of the automobile are fed; and a signal emitter through which the control unit responds to the input signals in the way of output signals sent to the starter solenoid supply, fuel cut-off device, accessories, or the indication system.


The signal receiver unit receives signals from several systems of the automobile including the clutch pedal, the gearshift lever, the mode selection switch, the bonnet, the doors, the horn, the timer unit, the battery, the engine speed sensor, and the vehicle speed sensor.
Conditions pertaining to and operation of the auto stop feature:
The clutch system is provided with a dedicated clutch switch that monitors the movement of the clutch pedal. The clutch switch normally remains in a closed position and opens when the clutch is pressed. In its open position it sends a signal to the control unit, provided that the clutch pedal is pressed to more than 90% of its movement-limit. In situations such as traffic jams, when the driver senses that the traffic is about to move, he presses the clutch pedal to shift the gear into a desired position in getting ready to start the vehicle. If the engine has been stopped during a traffic jam situation, pressing of the clutch to a significant extent would suggest that the driver wants to start the vehicle. The significant clutch movement is therefore considered as a trigger to automatic start of the engine. At the same time placing a restriction of the large movement of the clutch pedal ensures that the automatic starting of the engine happens only when the power train is 'open'. This is an advantageous safety feature of the present invention.
When the vehicle is stopped in a traffic jam or for any other reason, the vehicle
with manual gear system is expected to be in the neutral gear. The gear position in
the neutral therefore makes a logical trigger to stop the engine automatically. A


'neutral' switch assembly consisting of two switches that are connected in series and mounted close to the gear shift lever is therefore provided. As shown in Figure 2A, both the switches are normally closed whereby no signal is sent to the control unit. The assembly is designed in such a way that when any one switch opens due to the shifting of the gear lever from neutral to an engaged position, the signal to the control unit is cut off (see Figure 2B). Thus the control unit has a means of sensing the neutral position of gear shift lever.
A novel feature of the present invention is the mode selection switch. The driver has four options to choose from. He can opt for a. bypass of the entire auto stop-start system, b. bypass of the auto stop feature only, c. monitoring or warning period setting 1, and d. monitoring or warning period setting 2. The option of bypassing of the entire system or that of bypassing the stop feature of the system is useful in some instances such as rain or travelling through tunnels where the driver may want either to retain full control of the vehicle or prefers that the engine didn't stop in difficult situations. Whenever there is occurrence of rain, and the engine is stopped automatically by the system, there exists a good chance that engine may be over-cooled by the engine and restarting the stopped engine under these conditions may become difficult/impossible. Travelling through tunnels or through heavy-traffic situations without easy outlet is another example of a situation where the driver might prefer that the engine didn't stop. When the vehicle enters into a tunnel and if there is a traffic jam, and if the stop start system
stops the engine, the some of the essential or convenience features of the vehicle

such as the air-conditioning system will also be switched off. This may lead to discomfort of the driver inside the tunnel particularly during hot and humid weather. To avoid this situation, a means exists in the present system for detection of entry of vehicle into tunnel like environs particularly during day time based on the rate of change of ambient light and therefore automatically by-pass the stop start system from stopping the engine.
The monitoring period related options also come in handy so that the driver may prepare himself for the auto stop-start events. The mode selection switch, suitably placed in the vehicle, preferably near the steering wheel or in the instrument panel, is provided for this purpose. It consists of four positions, from which the driver can choose any one option. The mode selection switch may take any form such as a mechanical switch or an electronic switch with LCD indicator. The options to the driver include:
As a measure of reasonable safety, the bonnet of the vehicle which provides a cover to some of the vital parts of an automobile should be securely closed when the engine is running. The position of the bonnet is therefore considered as a consideration when making the decision to automatically stop or start the engine. A bonnet switch, which is provided below the bonnet, sends a signal to the signal receiver whenever bonnet is open.


Battery is a crucial part of a vehicle. Battery life and the quality of the battery during operational life depend on the demands on the battery's resources. For example, voltage level requirement during cranking operation is different from that during the engine- or vehicle-running mode. It is also important that the battery voltage remains within the required range for a predetermined period, before engine can be safely turned off. It is also important that the battery level remains at or above a certain level during the cranking of the engine. Cranking of engine at levels below the crank-threshold voltage leads to deterioration of the battery resulting in the damage to the battery itself and also to the parts it is trying to supply the power to. As an advantageous feature of the present invention, battery voltage is monitored over an adequate period and signal sent to the signal receiver as an input in making a decision to automatically stop the engine.
It has been an experience of many drivers that when a vehicle has stopped at a signal or in a traffic jam, and is the engine is left running, drivers often forget that the engine is still running and attempt to start it again. This can cause damage to the starter motor and unnecessarily drain the battery resources. Frequency terminal from the alternator, as an indicator of the engine speed, is fed to the signal receiver.
The control unit assesses the signals received by the signal receiver and
determines the compliance with the set of conditions that satisfy the eligibility for
automatic stoppage or start of the engine. It then either sends a signal to the fuel


cut-off device which controls the fuel supply to the engine and consequently its stoppage, or to the starter solenoid relay that controls the starter motor and consequently the start of the engine.
Depending on the status of signals received from the signal receiver, the control unit sends the malfunctioning related signal to the indicator in the cluster. The indicator is in the form of a light that glows continuously upon detection of a malfunction, or it can be in the form of an audio signal or an LCD device.
When the ignition key is turned on, and if no malfunction is detected by the auto stop-start system, the indicator indicates the 'OK' status by remaining ON for a predetermined period. For example, the indicator in the form of a light will remain lit for a predetermined period, preferably two seconds, after which it will stop glowing. As shown in Figure 6, the auto stop-start system is activated at this stage and will automatically turn off the engine or start it subject to compliance with predetermined set of conditions. If a malfunction is detected, the light will continue to glow. At this stage, the present invention allows the driver to operate the auto stop-start system through the mode-selection switch.
The turning on of the engine through the manual operation of the ignition key is taken as the 'first' start of the engine. As a key benefit of the present invention, after any first start of the engine, successive starts of the engine may be through
the auto stop-start system or directly through the operation of the ignition key.


As per the present invention, after the engine has been started through ignition key, the engine runs continuously without stoppage for a pre-defined duration of warm up period. Warm-up period is necessary for the general well being of the engine, as it ensures proper lubrication of all parts of the engine. It is well known to the parson skilled in the art that if the engine is stopped and started frequently before it is properly warmed up and lubricated, the engine life potentially reduces. As one of the key advantages of the present invention, the auto stop-start system is activated only after the warm-up period.
Another special feature of the invention is the warning signal sent to the driver that the engine is to be stopped or started automatically. Such signal is sent to the driver in advance. During this warning period, the driver has the option to override the decision of the auto stop-start system and reset it, through actions such as significant pressing of the clutch pedal or operation of the accelerator pedal or that of the horn. Resetting takes the auto stop-start system to the start of the monitoring regime. Once the engine has been stopped by the auto stop-start system, an indication is provided to the driver of the engine stoppage, The indication persists till the engine has been restarted
Typical voltage of a healthy battery when the alternator is not charging varies in
the range between 12.1v to 12.7v, the limits representing the least tolerable and
the best battery conditions. The minimum voltage required during the cranking of


the engine is approximately 8.5v. The system of the present invention has been designed such that, when the vehicle is in the running or operational mode, the auto stop mode will not be executed if the vehicle run-time voltage falls below 12.6, more preferably below 12.5. Similarly, the control unit records the battery voltage during the cranking event. If this voltage is less the crank-threshold voltage, the engine will possibly start, however, the system will thereafter bypass itself until the engine cranked manually through the operation of the ignition key.
Another key feature of the present invention is the facility to carry out the diagnosis of the malfunctioning related to the auto stop-start system. The diagnostic mode of the present invention is selected by pressing the clutch pedal followed by turning the ignition to ON position and maintaining the ignition in the same position for a predefined duration. Other pre-conditions for entry of diagnostic mode are gear shift lever should be in neutral position and mode selection switch is in by-pass mode (Refer Figure 8). If malfunction is detected, different signals are sent to the driver depending on the type of the malfunction (See figure 9.) In case no malfunction is detected, the indicator is turned off.
As per the present invention, the control unit has a means to identify the occurrence of rain. If rain is present, and the engine is stopped automatically, restarting of the engine may be difficult because the engine would have cooled down to a substantial extent. Hence, if the control unit recognises the presence of
rain, the system does not allow the engine to stop automatically.


As per the present invention, the control unit has a means to identify the entry of vehicle into tunnel by means of monitoring the rate of change of ambient light intensity. If the engine is stopped automatically in a tunnel, it may lead to the discomfort of the user. For example, if there is an accident in the tunnel, and hence there is a traffic jam, and if the engine stops automatically, A/C also will stop which will affect the comfort of the user particularly inside the tunnel and during the day. Hence, if the control unit recognises the entry of vehicle into tunnel particularly during the day, the system does not allow the engine to stop automatically.
Conditions pertaining to and operation of the auto stop feature:
As per the present invention, once the engine has been switched off automatically by the system, the system starts to monitor for set of conditions listed in the summary for automatic starting. If the conditions are found to be true, then engine is started. If any of the conditions are found not to be true, then the engine will not be started (See Figure 5).
As per the present invention, one of the pre-conditions for engine to start automatically is closure of bonnet. If the bonnet is open and when a user/technician is working on the engine and somebody else who is not aware of the automatic start stop system leads to automatic start of the engine (by pressing of clutch or blowing of the horn etc.), it will lead to serious consequences. Hence


it becomes an issue of safety concern and hence the engine will not be automatically started whenever the bonnet is open.
As per the present invention, if the engine is starting automatically, the starter motor will attempt to crank only for a pre-defined period, during which period, if the engine doesn't start. This suggests a malfunction outside the auto stop-start system, following which the auto stop-start system is reset automatically (see Figure 7). This prevents damage to starter and also preserves condition of battery by preventing it from continuous discharge.