Gear Shift Prompt System

Field of the Invention

The invention relates to a gear shift indication system for instructing a driver to shift into a gear suitable for the running state of a vehicle.

Description of the Prior Art

Vehicles with an internal combustion engine commonly have a geared transmission system to alter the torque available at the wheel based on vehicle load and road conditions. At the time of starting of the vehicle, the user selects a low gear so that high torque can be applied to the wheel. This ensures that the vehicle including loads can start moving, even move up an inclined road. Once the vehicle gains momentum, the user switches to a higher gear so that the vehicle speed can be increased at the expense of lower torque at the wheel. Depending upon the required vehicle speed, road gradients and vehicle load, the user chooses the gear condition and makes best use of the engine power output. For achieving maximum fuel efficiency, it is desirable to operate the engine at its rated torque and rated speed for a majority portion of the driving period. The choice of transmission gear condition has a strong influence on the fuel efficiency and vehicle performance.

The rider can decide on need to change the gear position based on the engine speed or vehicle speed indication provided on the instrument cluster. But the rider cannot always keep checking the instrument cluster speed reading or keep relying on the engine noise or vehicle acceleration to determine whether a gear shifting is required. Japanese Patent Application JP-A-200319912 discloses a gear shift prompt system which prompts the rider to shift to an optimum gear position based on engine load and vehicle speed data. The system has a controller with a shift map stored in its memory, similar to an automatic transmission system. Whenever the driver shifts to a gear different from the optimum gear position specified in the shift map, the controller arranges to provide a visual indication prompting the driver to change the gear position to the optimum position. Another Japanese Patent Application JP-A-62-94428 discloses a gear shift prompt system which cancels the gear shift prompt indication when the transmission is in neutral condition by using a neutral . switch. Also Japanese Patent Application JP-A-4-171352 discloses a gear shift prompt system in which the transmission gear position is estimated based on the change in ratio between engine speed and vehicle speed.

European Patent Application EP1930631 discloses a gear shift prompt system which cancels the prompt indication by correctly sensing the neutral condition of transmission even when the vehicle is moving down a slope and change in ratio between engine speed and vehicle speed is small without using a neutral switch. The system estimates the neutral condition by checking if the clutch is engaged and disengaged when an estimated gear position changes. In all of the above mentioned prior art, it is either required to have a dedicated gear position sensor and/or a vehicle speed sensor for sensing or estimating the gear position. But in low cost vehicles, gear position sensor or vehicle speed sensor is cost prohibitive. Vehicle speed indication in low cost vehicles is commonly achieved using an analog eddy current speedometer. Therefore it is an objective of the present invention to provide a gear shift prompt system, wherein the optimum gear position is determined and prompted to the user without using an additional gear position sensor and or/ vehicle speed sensor.

Summary of the Invention

The subject matter described herein relates to a gear shift prompt system for indicating to the rider the appropriate gear position to be selected for transmission, in the running state of the vehicle, so that the rider need not be bothered to decide when to change the gear while riding. The gear shift prompt system as per the present invention has an Electronic Control Unit (ECU) which accepts engine speed as input from a pulser coil magneto assembly and operates based on the average engine speed and the variation in engine speed of the vehicle, calculated under different vehicle operating conditions. Further, the ECU determines the optimum gear position to be selected by the rider by comparing the calculated values of average engine speed and variation in engine speed with predetermined values of average engine speed and predetermined values of variation in engine speed, corresponding to different vehicle operating conditions and wherein, the predetermined values of average engine speed and variation in engine speed are contained in a shift map stored in the memory of the ECU. Thus, based on the information processed by the ECU, the rider is prompted to shift gears in different riding conditions. The nature and further characteristic features of the present invention will be made clearer from the following descriptions made with reference to the accompanying drawings.

Brief Description of the Drawings

Figure 1 illustrates a motorcycle with a gear shift prompt system according to the present invention.

Figure 2 illustrates a system diagram outlining the connection of a pulser coil magneto assembly to an Electronic Control Unit (ECU).

Figure 3 illustrates a block diagram of the Electronic Control Unit (ECU).

Detailed Description of the Preferred Embodiments

An embodiment of a gear shift prompt system for a vehicle and a manner of operation of the gear shift prompt system in accordance to the present invention will be described hereunder with reference to the accompanying drawings. Various features of the gear shift prompt system in accordance to the present invention will become discernible from the following description set out hereunder. It is to be noted that although the present invention is exemplified for a two wheeled vehicle such as a motorcycle, however, the present invention may not be restricted only to a two wheeled vehicle and is applicable to a three wheeled and four wheeled vehicle. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

Figure 1 illustrates a motorcycle 100, according to the present invention wherein the motorcycle 100 includes a body frame 19, an engine 9, a front wheel 25, a rear wheel 27. The body frame 19 further comprises a head pipe 12, a main tube 11 extending horizontally and rearwardly from the head pipe 12 and a pair of side tubes 15 arranged side by side extending rearwardly from the main tube 11. In an upper portion of the head pipe 12, a handlebar 13 is rotatably integrally connected to the steering shaft (not shown). To a lower end of the steering shaft, a front fork 16 is attached and a front wheel 25 is journaled to a lower end of the front fork 16. The front wheel 25 is rotated in a certain range by steering the handlebar 13. A head light 36 is arranged on an upper portion of the front fork 16. An engine unit 9 is supported to the body frame 19 by being suspended in a front lower portion of the body frame 19. Further, a swing arm 26 is swingably connected to a rear lower portion of the body frame 19 and the swing arm 26 extends rearwards. The rear wheel 27 is rotatably supported at a rear end of the swing arm 26. Power from engine unit 9 suspended in a front lower portion of the body frame 19 is transmitted to the rear wheel 27 through a power drive mechanism, such as a drive chain, so as to drive and rotate the rear wheel 27.A rear wheel suspension 34 is arranged between the swing arm 26 and lower portion of side tube 15.

Further, a pulser coil magneto assembly 35, comprising a magneto assembly 10 and a pulser coil assembly 30 is mounted inside crankcase 32 of engine unit 9. Figure 2 illustrates a system diagram outlining the connection of the Electronic Control Unit (ECU) 40 to the pulser coil magneto assembly 35 and to an Ignition Coil 50. The pulser coil magneto assembly 35 comprises a magneto assembly 10 and a pulser coil assembly 30. The magneto assembly 10 comprising a permanent magnet rotor and a co-axial stator with coil winding is mounted within the crankcase 32, such that the permanent magnet rotor is directly coupled to the engine crankshaft and stator is connected with the crankcase 32. The magneto assembly 10 also comprises a projection 20 on the outer periphery of the rotor. Further, the pulser coil assembly 30 comprising a coil wound on a core and a permanent magnet is positioned inside the crankcase 32 of engine such that there is a small air gap between the pulser coil and the rotor of the magneto assembly 10. A signal indicative of the crankshaft position is generated due to electromagnetic induction phenomenon, -when the ferromagnetic projection 20 on the outer periphery of the permanent magnet rotor passes the pulser coil assembly 30.

A signal in the form of pulses is generated by • the pulser coil assembly 30 due to passage of ferromagnetic projection 20. These pulses are used to measure the time it takes for the ferromagnetic projection 20 to cross the pulser coil assembly 30. This constitutes engine speed of the vehicle and is an indication of the crankshaft and piston position as the rotor on which the ferromagnetic projection 20 is affixed, is directly coupled to the engine crankshaft. Further, variation in engine speed is indicative of engine load. Thereafter, this crankshaft position signal indicative of engine speed and engine load conditions, is provided to the ECU 40. The ECU by processing the crankshaft position signal data, not only aids in controlling ignition process but also provides output to an indication unit 70 for prompting the optimum gear position. While the ECU 40 controls the ignition process by providing electric signal to an ignition coil 50, which in turn generates a high voltage required for spark generation across spark plug 60, it prompts a rider to shift gears by providing an output signal to the indication unit 70, which in turn provides a visual or auditory response to the rider.

Figure 3 illustrates block diagram of the ECU, wherein the ECU 40 comprises a microcontroller 42, a signal conditioning unit 44, a driver circuit 46, and a power supply circuit 48. The microcontroller 42 performs arithmetic and logical calculations upon crankshaft position data in order to provide driving signals to ignition coil 50 and to provide signal to the indication unit 70. The signal conditioning unit 44 processes the crankshaft position signal received from pulser coil magneto assembly 35 and converts it into signals suitable for microcontroller 42. The driver circuit 46 provides appropriate output to ignition coil 50 and indication unit 70 based on microcontroller 42 output. The power supply circuit 48 provides ' conditioned power supply necessary for proper functioning of the microcontroller 42, signal conditioning circuit 44 and driver circuit 46. The microcontroller 42 calculates a variation in the engine speed by taking variation in engine speed for two consecutive rotation cycles, which in turn is provided by the crankshaft position data signal generated by the pulser coil magneto assembly 30. The microcontroller 42 also calculates a sample average of the engine speed. This sample average of engine speed is computed by taking average speed of two consecutive rotation cycles. A shift map specifying optimum gear position based on a predetermined average engine speed and predetermined variation in engine speed is stored within the microcontroller 42 of the ECU 40.

The shift map within the microcontroller 42 is derived based on data obtained by varying engine load conditions for a particular vehicle in different road conditions and by using different riding patterns used for the corresponding vehicle. Further, the microcontroller 42 decides the optimum gear position by comparing the calculated variation in engine speed value and the average of engine speed value with the predetermined values of variation in engine speed and average of engine speed respectively, specified in the shift map and provides appropriate output to driver circuit 46 which in turn provides output signal to the indication unit 70 for prompting the optimum gear position. The visual indication unit 70 gives a visual or auditory indication of the optimum gear position to be selected to the rider. Thus, the gear prompt system as per the present invention, by aiding the rider to select the optimum gear position under different riding conditions, helps to achieve better fuel efficiency and acceleration performance. Particularly for vehicles with low engine speed range, such as diesel vehicles, the gear prompt system assists the driver to recognize change in engine load conditions and correspondingly choose the optimum gear position. The use of a gear prompt system, such as the one described in the current invention is particularly desirable in low cost vehicles, because it does not involve the use of any gear position sensor or vehicle speed • sensor.

While the present invention has been shown and described with reference to the foregoing preferred embodiment, it will be apparent to those skilled in the art that changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined in the appended claims:

We Claim:

1. A gear shift prompt system for a vehicle having a manual transmission, the gear shift prompt system comprising: a pulser coil magneto assembly to generate a signal corresponding to engine speed of the vehicle; an Electronic Control Unit (ECU) to determine an optimum gear position corresponding to vehicle operating conditions, wherein the ECU calculates a value of variation in engine speed and a value of average engine speed by processing the signal corresponding to engine speed of the vehicle received from the pulser coil magneto assembly and compares a calculated value of variation in engine speed and a calculated value of average engine speed with a predetermined value of variation in engine speed and a predetermined value of average engine speed respectively; and an Indication Unit to indicate the optimum gear position to be selected corresponding to vehicle operating conditions, based on an output signal corresponding to the optimum gear position received from the ECU.

2. The gear shift prompt system as claimed in claim 1, wherein the - Electronic Control Unit (ECU) comprises a microcontroller, a signal conditioning unit, a driver circuit, and a power supply circuit.

3. The gear shift prompt system as claimed in claim 1, wherein the Electronic Control Unit (ECU) calculates the variation in engine speed by taking variation in engine speed of two consecutive rotation cycles.

4. The gear shift prompt system as claimed in claim 1, wherein the Electronic Control Unit (ECU) calculates the average engine speed by taking average speed of two consecutive rotation cycles.

5. The gear shift prompt system as claimed in claim 1, wherein the predetermined value of variation in engine speed and the predetermined value of average engine speed are contained in a shift map stored in the microcontroller of the Electronic Control Unit (ECU).

6. The gear shift prompt system as claimed in claim 1, wherein the predetermined value of variation in engine speed and the predetermined value of average engine speed, contained in the shift map stored in the microcontroller of the Electronic Control Unit (ECU) are determined based on varying engine load conditions under varying road conditions.

7. The gear shift prompt system as claimed in claim 1, wherein an indication of gear shift given by the Indication Unit is either visual or auditory.

8. A gear shift prompt system for prompting an optimum gear position to a rider, the method of gear shift prompting, comprising the steps of: calculating a variation in engine speed and an average engine speed based on an input engine speed received from a pulser coil assembly, by means of an Electronic Control Unit (ECU); comparing a calculated value of variation in engine speed and a calculated value of average engine speed with a predetermined value of variation in engine speed and a predetermined value of average engine speed respectively by means of the ECU, in order to determine an optimum gear position for the corresponding calculated value of variation in engine speed and the corresponding calculated value of average engine speed; and indicating an optimum gear position to be selected by a rider based on a comparison of the calculated value of variation in engine speed and a calculated value of average engine speed with a predetermined value of variation in engine speed and a predetermined value of average engine speed respectively, by means of an indication unit.

9. The gear shift prompt system as claimed in claim 8, wherein the step of calculating the variation in engine speed by the ECU involves calculation of engine speed of two consecutive rotation cycles.

10. The gear shift prompt system as claimed in claim 8, wherein the step of calculating the average engine speed by the ECU involves calculation of average engine speed of two consecutive rotation cycles.