CLIAMS:We claim:
1. A method for controlling idling of an engine (101), said method comprising the following steps,
detecting at least one engine operation parameter (S1);
determining a current state of engine operation as idling condition from said at least one engine operation parameter (S2);
operating purge valve (105) to supply the required quantity of air for idling (S3); and
assisting in fuel supply for idling with fuel vapors purged from a carbon canister (103) (S4).
2. A method as claimed in claim (1) wherein said engine operation parameter is selected from a group comprising engine speed signal (Pa), ignition pulse (Pb), intake manifold pressure signal (Pc), throttle position signal (Pd), engine temperature (Pe), air temperature (Pf), air fuel ratio or oxygen content from lambda sensor (Pg).
3. A method as claimed in claim (1) wherein said idling of engine (101) is controlled by said purge valve (105).
4. An engine control unit (107) of a vehicle, said engine control unit (107) (ECU) adapted to detect a at least one engine operation parameter and determine a current state of engine operation as idling condition from said parameter; said ECU further adapted to control a purge valve (105) and supply the required air for idling of engine (101) and assist in fuel supply with fuel vapors purged from said carbon canister (103).
5. An engine control unit (107)as claimed in claim (3) wherein said engine operation parameter is selected from a group comprising engine speed signal (Pa), ignition pulse (Pb), intake manifold pressure signal (Pc), throttle position signal (Pd), engine temperature (Pe), air temperature (Pf), air fuel ratio or oxygen content from lambda sensor (Pg).
6. A device (100) for controlling idling of an engine (101), said device (100) comprising,
a carbon canister (103) adapted to capture fuel vapors from a fuel tank (102);
a purge valve (105) adapted to supply air to the air intake path(106), said air adapted to flow via said carbon canister (103) to purge the captured fuel vapors into said intake path (106); and
a control unit (107)adapted to operate said purge valve (105) during idling condition to supply the required air and assist in fuel supply with fuel vapors purged from said carbon canister (103) .
7. A device (100) as claimed in claim (5) wherein said purge valve (105) operates as the idle control valve. ,TagSPECI:The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the invention:
[001] The invention relates to device and method for engine control. Particularly the invention relates to device and method for controlling engine operation during idling.

Background of the invention:
[002] For gasoline vehicles, due to increase in ambient temperature, the fuel in the tank may get evaporated. In systems with electronic fuel injection systems, there may be a solenoid purge valve to purge the fuel vapors from the tank into the intake manifold. Presently the purge valve is operated at predetermined conditions to fulfill the target evaporative emission legislation requirement. In some cases, if the carbon canister used for capturing fuel vapors can no longer adsorb more fuel vapors, the purge valve is opened allowing the ambient air to pass through the carbon canister and purge the fuel vapors into the air intake path of the engine.

[003] JP-2012026332 discloses one such evaporative fuel purging system for a vehicle with electronic fuel injection system.

[004] Further, for idling control the present vehicles use an idle control valve which allows a small quantity of air supply to the engine. This idle control valve is positioned across the throttle valve supply air to the engine. Thus, even if the throttle is not opened, fuel is injected in the engine based on the quantity of air supplied to the engine through the idle valve to maintain idling condition. The idle control valve can be controlled by the engine control unit allowing a desired quantity of air into the engine.

Brief description of the invention:
[005] The present vehicles include a plurality of different valves performing different functions. It is possible to achieve the desired outcome of different valves using a single valve. In accordance with this invention a purge valve in the vehicle is adapted to be used as an idle assist valve, thus eliminating the need for a separate idle assist valve.

[006] A method for operating of a vehicle engine during idling condition is envisaged in accordance with this invention. The method comprising the steps of detecting at least one engine operation parameter to determine a current state of engine operation as idling; operating a purge valve to supply the required quantity of air for idling; assisting in fuel supply for idling with fuel vapors purged from a carbon canister; and also to determine the proportion of fuel vapors purged and correcting the fuel quantity necessary to maintain the target stoichiometric ratio through the onboard fuel injector

Brief description of the drawings:
[007] The different embodiments of the invention are described with reference to the following accompanying drawings:
[008] Fig. 1 illustrates a schematic diagram representing a device (100) for idling of an engine (101) in a vehicle in accordance with one embodiment of the invention; and
[009] Fig. 2 illustrates a flowchart representing the method of idling of an engine (101) in a vehicle in accordance with one embodiment of the invention.

Detailed description of the embodiments:
[0010] Fig. 1 illustrates a schematic diagram representing a device (100) for idling of an engine (101) in a vehicle in accordance with one embodiment of the invention.

[0011] The device (100) for controlling idling of an engine (101) comprises a carbon canister (103) adapted to capture fuel vapors from a fuel tank (102). A purge valve (105) is adapted to supply air from ambient to the air intake path (106). The air supplied to the engine (101) on opening of the purge valve (105) flows via the carbon canister (103) to purge the captured fuel vapors. During idling condition, a control unit (107) is adapted to operate the purge valve (105) to supply the required air and assist in fuel supply with fuel vapors purged from said carbon canister (103). The purge valve (105) operates as an idle control valve, eliminating the need for a separate idle control valve.

[0012] Fig. 2 illustrates a flowchart representing the method of idling of an engine (101) in a vehicle in accordance with one embodiment of the invention.

[0013] The method for controlling idling of an engine (101) comprises the steps of detecting at least one engine operation parameter (S1) to identify a current state of engine operation as idling condition (S2). On detection of the idling condition of the engine (101) the purge valve (105) is operated to supply the required quantity of air for idling (S3) and assisting in fuel supply for idling with fuel vapors purged from a carbon canister (103) (S4). The engine operation parameter is selected from a group comprising engine speed signal (Pa), ignition pulse (Pb), intake manifold pressure signal (Pc), throttle position signal (Pd),engine temperature (Pe), air temperature (Pf) and air fuel ratio or oxygen content from lambda sensor (Pg). A closed loop idle control is possible by detecting at least one engine parameter and correcting air flow and fuel vapors from purge valve, fuel quantity from the fuel injector (109) and ignition timing. The idling of engine (101) is controlled by the purge valve (105) and the need for an idle control valve is eliminated.

[0014] It is envisaged in accordance with this invention, an engine control unit (107) (ECU) of a vehicle adapted to detect at least one engine operation parameter and determine a current state of engine operation as idling from the parameter. The ECU and further operates a purge valve (105) and supplies the required air for idling of engine (101) and assists in fuel supply with fuel vapors purged from said carbon canister (103).

[0015] The engine (101) is supplied with fuel from a fuel tank (102). Due to ambient temperature, the fuel in the tank (102) may evaporate. In order to recover the fuel that is evaporated, the fuel vapors from the tank (102) are allowed to pass through a carbon canister (103) where the fuel vapors get adsorbed. An air flow path is provided to the carbon canister (103) from the air filter (108). A purge valve (105) is positioned between the carbon canister (103) and the intake air path (106), so that it can be operated to selectively allow the ambient air and evaporated fuel vapors to flow from the carbon canister (103) to purge into the intake air path (106) downstream of the throttle valve (104) of the engine (101). The purge valve (105) is typically solenoid actuated or in some cases it can be a linear or rotary actuator. A control unit (107) receives inputs from various sensors in the vehicle corresponding to different engine control parameters. The control unit (107) identifies the current state of engine operation based on these parameters. If the control unit (107) identifies the present mode of operation of engine (101) as idle state condition, then the control unit (107) actuates the solenoid operated purge valve (105). On actuation of the purge valve (105), the air from the ambient and the fuel vapors from the carbon canister (103) are purged. The purged fuel vapors along with the air enter the intake air path (106) of the engine (101). The control unit (107) continues to keep the purge valve (105) in open condition or in a opens it in a predefined pattern which can be duty cycle based or linear or rotary steps as long as the engine (101) is idling so that the air required for idle state condition is provided through the carbon canister (103). The fuel required for idling is supplied by the fuel vapors purged from the carbon canister (103) and the fuel injectors (109).

[0016] The present device (100) eliminates the need for a separate idle control valve across the throttle to maintain air supply during idle state condition, thus reducing the cost. The purge valve (105) acts as the idle control valve and supplies the quantity of air required for idling. The fuel vapors assist in the fuel supply by injectors (109) to maintain idle state condition. This improves the fuel efficiency of the engine (101). Since the purge valve (105) is electronically controlled, the device (100) disclosed provides improved control on the fuel consumption in idle state condition.