A Device And Method For Starting An Engine

Field of the invention:

The present invention relates to a method for starting an engine.

Background of the invention:

Typically for starting a vehicle engine there is a provision of either a kick-start or an electric start. The vehicles with electric start option will be provided with a starter button which enables the engine start by engaging it with a starter motor.

In absence of an idle speed actuator in vehicles, a mechanical idle screw is provided. The position to which the screw is set is able to support the engine operation only at certain specific ambient conditions. The starting of the engine is particularly difficult during cold start conditions when the screw is set to a position which is not suitable. During such conditions it is required that the driver adjust the screw to an appropriate position manually.

Thus, there is a need for a simpler device for improved and easier starting of the engine of a vehicle.

Brief description of the invention:

It is an object of the present invention to provide a device and method for starting an engine which can enable quick and reliable starting under all ambient conditions. Further another object of the invention is reducing actuators and other hardware to make the system simpler and reduce the costs.

The present invention discloses a device for starting an engine reliably at all ambient conditions. The device includes a sensor for detecting position of a throttle valve in the air intake path of the engine. A control unit receives the throttle position data from the sensor. Based on this throttle position, a starter motor is adapted to be selectively engaged with the engine and crank the engine by the control unit.

The proposed invention enables the robustness of engine start in any ambient conditions since the required additional air mass is obtained during start with the opening of the throttle. Another advantage of the proposed invention is that, the damage to the starter or flywheel in case of manually engaging the starter even after the engine has started or during the engine running can be completely eliminated, as the control unit of the device in accordance with this invention recognizes the engine start and hence disengages the starter during the engine running.

The proposed invention eliminates the need of a starter button for starting the engine where the throttle is provided with a throttle position sensor. Hence additional hardware required for starting the engine like the starter button, wiring, fabrication of the housing and the like is eliminated and costs are saved.

The proposed invention can also be extended to vehicles with carburetor and a throttle position sensor, where the signal from the throttle position sensor can be used for starting the engine.

Brief description of the drawings:

The present invention is hereafter described with reference to the following accompanying drawings,

Fig. 1 illustrates a device for starting an engine in accordance with this invention; and

Fig. 2 illustrates flowchart for the method of starting an engine in accordance with this invention.

Detailed description of the invention:

Fig. 1 of the accompanying drawings illustrates a block diagram of a device in accordance with this invention. The device (10) for starting an engine (12) in accordance with the present invention comprises a sensor (14) for detecting position of a throttle valve (16) in the air intake path (18) of the engine (12). A control unit (20) is adapted to receive the throttle position data from the sensor (14). A starter motor (22) is selectively engaged with the engine (12) and cranks the engine (12) based on the throttle position data received by the control unit (20). The control unit (20) is provided with a database including different thresholds corresponding to throttle openings at different ambient temperatures. A temperature sensor (24) provides the ambient temperature to the control unit (20). An engine speed sensor (26) provides the engine speed to the control unit (20) for detecting successful starting of the engine (12).

Fig. 2 of the accompanying drawings illustrates a flowchart corresponding to a method for starting the engine in accordance with the present invention. The method for starting the engine (12) in accordance with the present invention comprises the following steps. The ignition of the engine (12) is switched ON, (SO). The throttle flap (16) is opened based on the driver input (SI). A throttle position sensor (14) senses the throttle (16) opening and transmits the same to a control unit (20), (S2). The control unit (20) on receiving the throttle position compares the throttle opening with a threshold value, (S3). If the throttle opening is greater than or equal to the threshold then the starter motor (22) is engaged with the engine (12) and the engine (12) is cranked, (S4). The starter motor (22) is disengaged after successful engine start, (S5).

The control unit (20) determines the ambient temperature by means of a temperature sensor (24). Based on this temperature the control unit (20) obtains the threshold for throttle opening from the database. The throttle opening is then compared with threshold for throttle opening at the ambient temperature as determined by the control unit (20). Engine speed is detected by an engine speed sensor (26) to determine successful engine start. After the engine (12) reaches a predetermined rpm the starter motor (22) is disengaged.

In the present electronic systems to start the engine (12) the user actuates a starter button based on the pre-conditions like brake, gear position, clutch input and the like to engage the starter and based on the available air mass and the ambient condition the engine starts. There is a possibility of longer cranking even after the engine (12) has started which may damage the starter motor (22) and flywheel. Also reliable engine start cannot be ensured at all ambient conditions. At certain ambient conditions additional air mass may be required to increase the fuel to air ratio. By using the mechanical choke in case of the vehicle provided with an idle screw.

In the present invention, the control unit (20) for the vehicle includes a pre-calibrated threshold depending on the optimum throttle opening to support the engine start at various ambient conditions. When the throttle (14) is opened to match this threshold, the control unit (20) actuates the starter motor (22) and hence the engine (12) is started reliably at all ambient conditions. Further the engine (12) status is available by the engine speed sensor (26) and the starter motor (22) can be disengaged immediately after the engine (12) reaches a predetermined speed. Hence long cranking situation after the engine (12) has started can be avoided and prevent any damages to the starter motor (22) or the flywheel.

The proposed invention can also be used even in simplified approach in case of a carburetor engine, where no electronic control exists. This can be realized by using a simple throttle position switch indicating the throttle opening and hence enabling the starter for predetermined duration to start the engine.

It must be understood that the embodiments explained in the description above are only illustrative and do not limit the scope of the invention. The scope is only limited by the scope of the claim. Many modifications in terms of the means of integrating the pressure sensor to the fuel pump are envisaged and are within the scope of this invention.

WE CLAIM:

1. A device (10) for starting an engine (12), said device comprising

a sensor (14) for detecting position of a throttle valve (16) in the air intake path (18) of the engine (12); a control unit (20) adapted to receive the throttle position data from said sensor (14); and a starter motor (22) adapted to be selectively engaged with the engine (12) and crank the engine (12) based on throttle position data received by said control unit (20).

2. A device (10) as claimed in claim (1) wherein, said control unit (20) includes a table providing different thresholds corresponding to throttle openings at different temperatures.

3. A device (10) as claimed in claim (1) wherein, a temperature sensor (24) provides the ambient temperature to said control unit (20).

4. A device (10) as claimed in claim (1) wherein, an engine speed sensor (26) provides the control unit (20) the engine speed to detect successful starting of the engine (12).

5. A method for starting an engine, said method comprising the following steps, switching ON the ignition of the engine (SO);

opening the throttle flap by the driver input (SI); sensing the throttle opening by a throttle position sensor and transmitting the same to a control unit (S2);

comparing the throttle opening with a threshold value for throttle position (S3); engaging a starter motor with the engine and cranking the engine (S4); and

disengaging the starter motor after successful engine start (S5).

6. A method as claimed in claim (5) wherein, control unit determines the ambient temperature by means of a temperature sensor.

7. A method as claimed in claim (5) and (6) wherein, the throttle opening is compared with threshold for throttle opening at the temperature determined by the control unit.

8. A method as claimed in claim (5) wherein by detecting the engine speed after cranking successful engine start is detected to disengage the starter motor.

9. A device for starting an engine with a carburetor wherein a throttle position switch selectively enables a starter motor for engine start operation.

10. A method for starting an engine with a carburetor comprising the steps of detecting throttle opening by a throttle position switch and enabling the starter motor for engine start.