FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION Device to indicate better gear shift practices

APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,

24 Homi Mody Street, Hutatma Chowk,
-J Mumbai 400 001 Maharashtra, India
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INVENTORS
Mr. Dattatraya R. Katkar, Mr. Deepak S. Kulkarni 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
This invention relates to a device that indicates the vehicle driver gear to be engaged while driving the vehicle in accordance with the manufacturer's recommendations. It also detects the mismatch and provides an audio visual signal to draw the attention of the driver.
BACKGROUND OF THE INVENTION
Rapid growth of industrialization along with economic developments are the driving force for increasing use of the automobiles in the country. The increase in usage and number of kilometers traveled results in, increasing use of fuels. Optimum and efficient use of fuel during operation will result in reduction in fuel consumption. The fuel saving has great significance at national as well as global level. To address this problem Automotive manufacturers are developing new fuel efficient and environmentally friendly engines and vehicles. On the other hand, in-use vehicles constitute a large fraction of automobile population. Attempts to improve the fuel economy of in use vehicles also will have a considerable positive impact on fuel savings.
The on road fuel economy is a complex phenomenon and in general it is a function of following parameters -
i) Type of vehicle ii) Traffic pattern iii) Driving pattern Out of the above parameters, only driving pattern is user dependent and vary significantly from user to user. Vehicle manufacturers specify the gear to be used as a function of vehicle speed in order to achieve better fuel economy in the owners manual. The present invention relates to a device that provides an indication to the
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driver while driving regarding the gear to be used inline with the vehicle manufacturer's specifications for achieving better fuel economy.
PRIOR ART
US patent 4539868 teaches a method for indicating gear shifting operation to be performed which comprises the steps of calculating current engine load from the intake air flow and the number of engine revolutions comparing the current engine load thus calculated with predetermined engine load constant, calculating current shift position from the result of the comparison, seeking the first engine load operation function and the second engine load operation function from known equal fuel flow rate consumption curves, comparing the first engine load operation function thus sought with said current engine load and indicating either shift-up or shift-down operation to be performed by the driver in accordance with the result of the comparison. According to the method in the present invention, preferable shift positions to be performed in the optimum fuel consumption rate can be thereby enabling the maximum engine fuel performance to be carried out during running of a car.
US patent 4701853 teaches a method and device for signaling to a vehicle operator that a higher gear should be selected. A microprocessor is connected so that it can sense the rotational speed of the engine and the vehicle road speed. The quotient of the road speed and the engine speed is determined and compared with the series of the predetermined quotients one for each of the gear selector positions, and the engaged gear is thus determined. For each gear there is registered the quotient of its own and that of the next higher gear position, the quotient being zero for the highest gear. The engine speed signal is multiplied with the by this gear ratio value for the gear engaged and is compared with the maximum value, a signal is sent that the gear
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change should be made. In accordance with the preferred embodiment, the fact is utilized that the generator, if the generator belt slips, will produce an engine speed value which is too low, so that the first mentioned measured quotient will not agree with the predetermined quotient. An error signal is then sent indicating the need for
service.
US patent 4683455 teaches a shifting timing indicating system for a vehicle which includes a control circuit having an engine rpm sensor for detecting the engine rpm and a rpm comparator which receives the output of the engine rpm sensor and determines whether the engine rpm exceeds a preset value. The control circuit opens a shift up signal when the engine rpm exceeds the preset value. A shift-up indicator receives the shift-up signal from the control circuit and makes a shift-up display to direct the operator of the vehicle to shift up. An acceleration detecting circuit detects the rate of increase in engine load and the shift up indicator is inhibited from making the shift-up display for a predetermined time interval which is extended with increase in the rate of increase in engine load.
It is worthwhile to note at this point that, even though the above invention detects the gear engaged it does not take into account the running in period and gear shift recommendations during this period. The engine running in period is also important from reducing engine friction and the engine is likely to get damaged if the engine speeds are not maintained during this period.
OBJECT OF THIS INVENTION
• The main object of this invention is to provide a device that recommends the vehicle driver the gear to be used for better fuel economy.
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• Yet another object of this invention is to provide a device that provides an indication to the vehicle driver regarding the appropriate gear to be used during initial running in period.
• Yet another object of this invention is to provide a device that compares the gear currently engaged with a gear suited for better fuel economy based on vehicle speed inline with the vehicle manufacturers' recommendations.
• Yet another object of this invention is to provide a device to preempt better gear usage that can be retrofitted in in-use vehicles.
• Yet another object of this invention is to provide a simple and cost effective device to provide this indication to the vehicle driver regarding the appropriate gear to be sued.
SUMMARY OF INVENTION
This device for preempting better gear utilization for an automobile comprises of an electronic unit that is programmed to indicate the gear to be used as per manufacturer's recommendations. These appropriate gear recommendation is primarily function of vehicle speed. The device receives the input signal from vehicle speed sensor which is mounted on gearbox output shaft. It then converts the gear box shaft output speed to the angular speed of the wheels by considering the differential ratio and further into the linear speed by multiplying by tyre perimeter. Subsequently, the electronic unit compares the vehicle sped sensor input signal against the manufacturer's recommendations on gear usage, which is programmed, into it. Accordingly the device then flashes the appropriate gear to be used for current vehicle operating condition. If the current gear used is different than, in addition to the indication of the appropriate gear, the electronic unit also provides an audio signal In addition, the unit also has an integrating feature. The integrating features
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counts total number of rotations for the wheels and then by multiplying by the tyre perimeter, it is converted into the total distance traveled. The cumulative distance traveled is used to determine whether the running in period of the vehicle is over. Since the vehicle manufacturers give different gear usage recommendations based on distance traveled information. Thus the electronic unit provides the indication about the gear to be used while driving the vehicle including the running in period.
Accordingly, the invention relates to a device to indicate gearshift operation in a vehicle comprising: means for receiving engine speed signal; means for receiving vehicle speed signal; means for computing the vehicle speed and current gear engaged; means for comparing said vehicle speed and said current gear engaged against optimum gear to be engaged; and means for generating an audio and visual signal if said vehicle speed and said current gear engaged do not match said allowable vehicle speed and allowable gear to be engaged.
Also, the invention relates to a method for indicating gearshift operation in a vehicle comprising the steps of: obtaining engine speed signal; obtaining vehicle speed signal; computing the vehicle speed and current gear engaged; comparing said vehicle speed and said current gear engaged against optimum gear to be engaged; and generating an audio and visual signal if said vehicle speed and said current gear engaged do not match said allowable vehicle speed and allowable gear to be engaged.
BRIEF DESCRIPTION OF DRAWINGS
The sketches showing details of the device for preempting better gear utilization, arrangement
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Fig. 1 shows the schematic arrangement of components for an device to preempt
better gear utilization for a vehicle.
Fig.2 shows manufacturer's recommendations regarding gear usage regarding as per
vehicle speed.
Figure 3 shows the schematic of the electronic device that preempts the better gear
utilization.
Figure 4 shows the flow chart followed for indication the appropriate gear and
preempting its usage
DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same
Figure 1 shows the schematic arrangement that preempts better gear utilization on vehicle. In a typical layout a gear box (1) is connected to an engine (2). A propeller shaft (3) connects gear box and the differential (4). A rotational speed sensor (5) is mounted at the output shaft of the gear box. Alternately, the electrical signal from the vehicle speed signal can also be used. The engine speed signal (6) is taken from an engine speed sensor or from the alternator. The controller (7) receives an engine speed signal and vehicle speed signal. Based on these inputs the electronic unit determines the vehicle speed, current gear engaged. It then compares vehicle speed and gear engaged against the manufacturer's recommendations which are programmed into it. If there is a mismatch the device gives an audio signal and flashes the appropriate gear to be used. The integrator part of the device calculates total distance traveled. It then compares the cumulative distance traveled with the vehicle running in period as recommended by the manufactures, which is also
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programmed into it. Vehicle manufacturers have a separate gear shift recommendation during initial running in period. This is to avoid the engine over speeding during running in period. The Electronic unit compares the cumulative distance traveled with the running in distance recommendations and recommends the appropriate gear accordingly.
Fig. 2 shows the details of the manufacturers recommendations regarding gear utilization depending upon vehicle speed. The tables indicate the following -
a) Maximum speed in each gear during running in period.
b) Recommendations for gear usage during normal vehicle running
These recommendations are given in owners manual. However, these recommendations are not followed at all the times due to variation in driving practice and there is no mechanism to make the driver aware of these recommendations while running the vehicle.
Figure 3 shows the schematic of the electronic device that preempts better gear utilization. The controller (6) is a microprocessor based electronic unit capable of receiving multiple inputs and storing various parameters in the memory. Following vehicle model specific parameters are programmed into the controller -
i) Running in period - Distance in km.
ii) Rear axle ratio -
iii) Dynamic tyre radius There parameters are programmed into the electronic controller by the installer of the controller in the form of input template. Similarly, if the device to preempt better gear usage is to be retrofitted, the controller can share the input signals from existing engine speed and vehicle speed sensors. Alternately, the engine speed signal can be taken from the alternator and the vehicle speed signal is taken from the dual output
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vehicle speed sensor. In case of OE fitment of this device at the vehicle manufacturer's end, all the design provisions are made on engine and vehicle to provide the required input signals. In addition, the controller receives the following input signals from the vehicle (31)-
a) Vehicle speed signal from the vehicle speed sensor.
b) The engine speed signal is taken from engine speed sensor or from alternator. Based on the above inputs, the electronic controller performs the following calculations -
Wheel rotational speed = Gearbox out put speed / Rear axle ratio
Vehicle Linear speed = Wheel rotational speed x Tyre perimeter
Cumulative distance traveled = Total wheel rotations x Tyre perimeter
Total wheel rotations are calculated using instantaneous wheel rotations by electronic
integration.
Further, using the above derived parameters, the controller decides whether the
running in period is completed. Accordingly it selects the look up table for indicating
the appropriate gear. After selecting the proper look up table, the controller finally
provides the following outputs (32).
a) Indicate the appropriate gear to be engaged if gear currently used is same as appropriate gear.
b) Indicate the appropriate gear (indicated in flashing condition ) and an alarm if the gear currently engaged is different than the appropriate gear.
Figure 4 shows the logical steps in recommending suitable gear to be used. The steps are as below —
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i) Based on the engine speed and the gear box shaft output speed vehicle
speed inputs the electronic device calculates the gear currently engaged, ii) Using the integrator function it calculates the total distance traveled by the
vehicle. This is done on a continuous basis, iii) Based on this the electronic device confirms whether the vehicle has
completed the running in by comparing it with the running in distance
which is programmed into the device, iv) Based on this the electronic unit selects the appropriate look up table for
gear utilization, v) Comparing the current vehicle speed in the look up table, the controller
displays the appropriate gear to be engaged, vi) Then the electronic controller compares the current gear engaged with the
appropriate gear to be used as determined in step II. vii) If there is a mismatch between gear currently engaged and the gear as
determined in step I, the electronic controller flashes the display and in
addition provides an audio signal. The flashing continues till the corrective
action is taken.
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.
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We Claim
1. A device to indicate gearshift operation in a vehicle comprising:
means for receiving engine speed signal;
means for receiving vehicle speed signal;
means for computing the current gear engaged;
means for comparing said vehicle speed and said current gear engaged against optimum gear to be engaged ; and
means for generating an audio and visual signal if said vehicle speed and said current gear engaged do not match said optimum gear to be engaged.
2. The device as claimed in claim 1 wherein said optimum gear to be engaged as a function of vehicle speed is programmed in said device.
3. The device as claimed in claim 1, wherein said device is further configured to compare cumulative distance travelled by said vehicle and comparing the same with recommended running in distance.
4. The device as claimed in claim 3, wherein when said cumulative distance traveled by said vehicle is lesser than said running in distance, said device is configured to compare said vehicle speed and said current gear engaged against optimum gear to be engaged in the running in condition of the vehicle; and to generate an audio and visual signal if said vehicle speed and said current gear engaged do not match said optimum gear to be engaged in said running in condition.
5. The device as claimed in claim 3, wherein when said cumulative distance traveled by said vehicle is greater than said running in distance said device is configured to compare said vehicle speed and said current gear engaged against optimum gear to be engaged in the normal running condition of the vehicle; and to generate an audio and visual signal if
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said vehicle speed and said current gear engaged do not match said optimum gear to be engaged in said normal running condition.
6. The device as claimed in claim 1-5, wherein said device is capable of being retrofitted and configured to obtain the input signals from existing engine speed and vehicle speed sensors.
7. The device as claimed in claim 1-6, wherein said engine speed signal can be obtained from the alternator and the vehicle speed signal can be obtained from the dual output vehicle speed sensor.
8. A method for indicating gearshift operation in a vehicle comprising the steps of:
obtaining engine speed signal;
obtaining vehicle speed signal;
computing the current gear engaged;
comparing said vehicle speed and said current gear engaged against optimum gear to be engaged; and
generating an audio and visual signal if said vehicle speed and said current gear engaged do not match said optimum gear to be engaged.
9. The method as claimed in claim 8, further comprising the step of:
comparing cumulative distance traveled by said vehicle with recommended running in distance.
10. The method as claimed in claim 9, wherein when said cumulative distance traveled
by said vehicle is lesser than said running in distance said method further comprises the
steps of:
comparing said vehicle speed and said current gear engaged against optimum gear to be engaged and gear to be engaged in the running in condition of the vehicle; and
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generating an audio and visual signal if said vehicle speed and said current gear engaged do not match said optimum gear to be engaged in said running in condition.
11. The method as claimed in claim 9, wherein when said cumulative distance traveled by said vehicle is greater than said running in distance said method further comprises the steps of:
comparing said vehicle speed and said current gear engaged against allowable vehicle speed and gear to be engaged in the normal running condition of the vehicle; and
generating an audio and visual signal if said vehicle speed and said current gear engaged do not match said optimum gear to be engaged in said normal running condition.
Dated this 25th day of November 2008
TATA MOTORS LIMITED By their Agent & Attorney
(Karuna Goleria) of DePENNING & DePENNING
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