Torque Damping System

Field of the Invention:

The present invention is related to torque damping system and more particularly to engine torque damping for a carburetted vehicle.

Background of the Invention:

In an ..automated manual transmission (AMT) engine, gear shifting is achieved automatically without the driver interacting physically with gear and clutch actuation mechanism. The gear and clutch shifting is performed by an electronic control unit (ECU) actuating different actuators. The full system including the IC (internal combustion) engine, transmission and final drive system goes through a transition state during the gear shifting. The torque produced by the IC engine needs to be reduced during the gear shifting operation time. The torque interruption is performed to remove jerky feeling. The engine speed shoots up during the shifting period without this torque interruption. This sudden jerk affects the drivability of the vehicle as well as it affects the life of the mechanical components of the other power-train components.

In case of a manual transmission vehicle the torque interruption is performed by the driver by reducing the throttle position /opening during gear shifting operation. In case of fuel injected vehicle, the same is realized by partial cutting of fuel injection pulses and retarding the ignition timing.

In case of carburetted vehicle, the torque interruption is not possible with existing setup.

Therefore the present invention tries to provide a torque interruption in carburetted AMT vehicle.

Summary of the Invention:

An object of the present invention is to provide engine torque damping during gear shifting for a carburetted AMT vehicle.

Another object of the present invention is to provide a secondary air flow path parallel to carburettor to reduce the air pressure.

Yet another object of the present invention is to provide a controller which gives a valve open command to the secondary air flow path.

Yet further object of the present invention is to provide a controller which controls the ignition time during gear shift in AMT vehicle.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Brief description of the Drawings:

The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein

Figure 1 shows a conventional scooter type vehicle.

Figure 2 shows block diagram for the system according to the present invention.

Figure 3 shows the working flowchart for the system according to the present invention.

Detail Description of the Invention:

The present invention now will be described more fully hereinafter with different embodiments. This invention may, however, be embodied in many different "forms and should not be construed as limited to the embodiments set forth herein; rather those embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the invention to those skilled in the art.

With reference to Ffigure 1, 1 isa front wheel, 2 denotes a front fork, 3 denotes a front fender, 4 denotes a front cover, 5 denotes a leg shield made of resin or .metal, 6 denotes a handle bar cover, 7 denotes a headlight, 8 denotes a handle bar ,17 denotes a rear fender and 18 denotes tail lamp.

The center of the body forms a low floor board 9 for functioning as a part for putting feet and a under cowl 10 which is located below the rider's seat and covers at least a part of the engine, The under cowl is made up of metal or resin. The under cowl is hinged to the seat 11. A utility box 12 opens from the rear end to hinged portion. The utility box 12 is provided under the seat extending longitudinally of a vehicle body and the inside of the utility box has a large capacity so that a large article can be housed. A main frame 14 extended along the center of the body before and behind and made of a metallic pipe and is provided under the floor board 9. A swing type power unit 13 is coupled to the rear end of the main frame 14.

A rear wheel 15 is supported on one side of the rear end of the swing type power unit 13. The swing type power unit 13 is suspended in the rear of a body frame.

The side covers 16 both on left and right sides, covers the utility box 12 and other parts of the vehicle, thereby providing a good appearance to the vehicle.

According to one embodiment of the present invention and referring to Figure 2, an automatic manual transmission equipped engine is supported by a scooter type body frame and having a clutch actuator configured to actuate clutch and shift actuator configured to shift the change gears. A controller 201 is provided for activating the said shift actuator and the clutch actuator.

A secondary air-path with a flow control valve 202 is placed parallel to a carburettor 203. The flow control valve 202 is activated in a controlled manner by an electric control signal or by a pneumatic signal or by any other actuating mechanism or like. The control signal for the controlling the flow control valve is generated by an electric control unit (ECU) 201 which can be the same said controller which activates the shift actuator and clutch actuator. The electric control unit 201 activates the control signal just before initiating gear shifting mechanism.

The opening of said flow control valve 202 reduces the air pressure difference across the carburettor 203.

The amount of fuel entering the cylinder 204 for a carburetted engine is controlled by the negative pressure generated by the airflow through the main air path of the carburettor 203. The said ECU 201 activates the secondary air path 202 in a calculated manner to reduce the air pressure difference across the carburettor 203. The reduction of fuel flowing to the engine 204 reduces the torque generation capability of the engine.

The other control variable for the IC engine torque generation function is the ignition timing. The ignition timing is retarded in a control manner by the ECU 201 just before initiating gear shifting mechanism.
The ECU 201 closes the parallel secondary air-path in a controlled manner after the gear shifting and returns to the normal ignition timing. The controlled manner is very important during the recovery period as it results how dynamically the vehicle accelerate/decelerate after gearshift.

The working flowchart for the system is explained hereinafter. The present invention works only during gear shifting operation. Referring to Figure 3, the controller 201 in step 001 read the values of throttle position signal, engine speed, vehicle speed, gear position signal, clutch position signal, brake signal, based on the readings the controller decides whether gear shifting is required in step 002. If the controller decides that gear shifting is required, it then calculates the present airflow and fuel flow to the engine in step 003. Further in step 004 the controller calculates the required rate of opening of the secondary airflow control valve and rate of ignition time retardation. After that in step 005 and 006 the controller calculates the control signal for the gas path actuator opening and ignition time retardation. Then in the next step 007, step 008 and step 009 the clutch is disengaged, gear is shifted and then again clutch is engaged. After which the controller calculates the required rate of closing of the secondary air flow control valve and rate of ignition time retardation recovery in step 010. In the next step parallely it calculates the control signal for the gas path actuator closing and the ignition time retardation recovery in step 011 and step 012.

The system according to the present invention opens the secondary air path 202 and retards the ignition timing just before the clutch disengagement process starts. As a result of this, engine torque output reduces during the gear shift period. Thus the proposed system neglects the effect of an open TPS during this period.

The system according to the present invention reduces the engine output torque during gear shifting operation for a carburettor based automated manual transmission vehicle. In case of a manual transmission carburetted vehicle, the engine torques is reduced by the driver himself/herself during gear shifting operation. In case of an AMT based vehicle, the ECU 201 decides when to do the gear shifting. So the driver need not know about the point of gear shifting. Due to the automatic gear shifting process, it
is necessary to reduce the engine output torque without driver intervention.

the present system reduces fuel flow and retards the ignition timing for IC engine during gear shifting. The fuel flow reduction is achieved in a control manner by controlling airflow through a secondary air path 202 which is connected parallel to the main air path of the carburettor 203. The mass flow of the air is controlled by modulating a flow control valve by an ECU 201. Simultaneously ignition time is retarded to reduce the engine output torque. The present system stops working once the gear shifting process is finished.

The invention being thus described,, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the claims.

We Claim:

1. A torque damping system for a carburetted automatic manual transmission vehicle comprising:

an automatic manual transmission equipped engine having a clutch actuator configured to actuate clutch and shift actuator configured to shift gears;

a controller for activating the shift actuator and clutch actuator;

a carburettor having a first air path;

a secondary air path with a flow control valve placed parallel to the first air path; and

wherein the controller regulates the flow control valve and ignition timing during gear shifting.

2. The torque damping system as claimed in claim 1, wherein the automatic manual transmission equipped engine is preferably supported on a scooter type body frame.

3. The torque damping system as claimed in claim 1, wherein the controller calculates the ignition timing retardation before gear shifting and ignition timing retardation recovery after gear shifting

4. The torque damping system as claimed in claim 1, wherein the controller calculates the required rate of opening the secondary air flow control valve before gear shifting and the required rate of closing of the secondary air flow control valve.

5. The torque damping system as claimed in claim 1, wherein the secondary air path with a flow control valve helps in reducing air pressure difference across the carburettor.

6. A torque damping system for a carburetted automatic manual transmission vehicle substantially as herein described and illustrated.