CLIAMS:We claim,
1. A throttle body for controlling air flow to an engine; said throttle body characterized by an encoded data matrix corresponding to its air flow characteristics inscribed on the throttle body, wherein said encoded data matrix is machine readable.
2. A method for manufacturing a throttle body, said method characterized in that,
measuring actual air flow characteristics of a throttle body;
encoding the measured air flow characteristics of the throttle body to form a data matrix; and
inscribing the encoded data matrix on said throttle body.
3. A method as claimed in claim (2) is performed after completing the assembly of a throttle body.
4. A method as claimed in claim (2) wherein said encoded data matrix inscribed on the throttle body is machine readable.
5. A method as claimed in claim (2) wherein actual air flow characteristics are measured at pre defined strategic operating points of the throttle.
6. A method for configuring an electronic control unit (ECU) with air flow characteristics of a throttle body; said method comprising,
scanning the encoded data matrix on the throttle body by a scanning means in communication with the ECU;
decoding the encoded data matrix to obtain air flow characteristics of the throttle body; and
storing the decoded air flow characteristics of the throttle body in an ECU memory.
7. A method as claimed in claim (6) wherein scanning of the encoded data matrix inscribed on the throttle body is done at the time of engine assembly or vehicle assembly or during end of line testing of the vehicle.
8. A method as claimed in claim (6) wherein the ECU controls the engine operation based on the decoded air flow characteristics stored in the memory.
,TagSPECI:Field of the invention:
[001] The invention relates to a throttle for air flow control in vehicles.

Background of the invention:
[002] For efficient operation of an engine it is necessary that the air fuel ratio should be controlled accurately. Typically this is achieved by using on board sensors which provide a feedback to the fuel injection. In low cost electronic fuel injection (EFI) systems, the on-board sensors required for controlling the air fuel ratio accurately are absent. Thus, it is necessary to have an accurate and robust pre-control or a feed forward control in such systems. The two main sub systems that influence the control of the air fuel ratio are the air system (Throttle body assembly) and the fuel system (Fuel supply module and fuel injector). For the engine management system to function effectively the air flow from the throttle body has to be maintained at the predefined tolerance level. To maintain the specified tolerance values in the throttle body all the processes relating to manufacturing the throttle body need to be precisely controlled. Each of the process has to meet the tight tolerance specifications which lead to increase in cost. In case of any deviation to the tolerance the system functionality will be affected adversely.

[003] There is a need for a system which can overcome the tolerance related issues during manufacturing of throttle assemblies and reduce the necessity of meeting the tolerance specifications. Also there is a need for an air system which enables efficient operation of the engine by providing accurate air supply to the engine.

Brief description of the invention:
[004] The present invention proposes a method for manufacturing a throttle body which does not require adherence to tight tolerance limits and reduces the overall effective cost and effort of manufacturing the throttle assembly.

[005] The present invention describes a throttle body for controlling air flow to an engine. The throttle body has an encoded data matrix corresponding to its air flow characteristics inscribed on the throttle body. This encoded data matrix is machine readable. Actual air flow characteristics of a throttle body are measured for each throttle body manufactured. The measured air flow characteristics of the throttle body are encoded to form a data matrix and this data matrix is inscribed on the throttle body. The inscribed encoded data matrix on the throttle body is scanned by a scanning means in communication with the engine ECU. The ECU decodes the encoded data matrix to obtain air flow characteristics of the throttle body which are stored in the ECU memory. The operation of the engine is controlled based on these air flow characteristics which are stored in the memory.
[006] The present invention enables to achieve accurate control over the air supply from the throttle body by providing the exact air flow characteristics of the particular throttle body being used to the ECU. The unique air flow characteristics for each throttle body assembly at the selected operating points is encoded in the data matrix inscribed on the throttle body and the ECU of the engine is configured to these characteristics during the assembly of throttle to the engine. Thus, the need of sensors for the online adaptation or the complex and time consuming adaptation technique during the vehicle production line can be eliminated. Also the need of accurate and precision manufacturing process to maintain the high tolerance levels can be completely eliminated, reducing the overall production cost. The proposed invention reduces the need for the additional sensors and meets the target emission legislation with improved fuel efficiency and reduced overall vehicle cost in comparison to the existing systems.

Brief description of the drawings:
[007] The present invention is described with reference to the following accompanying drawings,
[008] Fig. 1 illustrates a table indicating the air flow characteristics of a throttle body measured at predefined strategic points and an encoded data matrix to be inscribed on the throttle body, in accordance with one embodiment of the invention; and
[009] Fig. 2 illustrates a graph representing the air flow characteristics as encoded in the data matrix in accordance with one embodiment of the invention.
Detailed description of the embodiments:
[0010] Fig. 1 illustrates a table indicating the air flow characteristics of a throttle body measured at predefined strategic points and an encoded data matrix to be inscribed on the throttle body, in accordance with one embodiment of the invention.
[0011] The air flow characteristics of each throttle that is manufactured are measured at end of the manufacturing line. These air flow characteristics are measured at certain pre defined strategic points. The table A in Fig. 1 indicates the measured air flow characteristics of a throttle. The measured airflow characteristics are encoded using suitable encoding algorithms to form a data matrix (M). The encoded data matrix (M) is inscribed on the throttle body using suitable inscribing methods.
[0012] A method for manufacturing a throttle body is envisaged in accordance with one embodiment of the present invention. The steps for manufacturing throttle assemblies include the measuring of actual air flow characteristics of a throttle body at end of the manufacturing line. Further the measured air flow characteristics are encoded to form a data matrix and inscribing the encoded data matrix on said throttle body. The method is performed after completing the assembly of a throttle body. The encoded data matrix inscribed on the throttle body is in a machine readable format. In accordance with one embodiment of the method the actual air flow characteristics are measured at pre defined strategic operating points of the throttle. For example as shown in table A, the air flow is measured at strategic points based on opening of the throttle. The actual values measured for each of the throttle body manufactured will vary and the values listed in the table A are only for illustrative purpose. These air flow characteristics of the throttle body are encoded to form the data matrix (M) by means of a suitable encoding algorithm. The data matrix as shown in the fig. 1 is generated using an encoding algorithm in accordance with one embodiment of the invention and similar other encoding algorithms may be used for the same.
[0013] Fig. 2 illustrates a graph representing the air flow characteristics of a throttle corresponding to the throttle opening angles as encoded in the data matrix in accordance with one embodiment of the invention.
[0014] In accordance with one embodiment of the present invention the measuring of air flow characteristics is carried out at certain pre defined strategic points of operation of the throttle. P1, P2, P3, P4 P5 and P6 are the strategic points in accordance with one embodiment of the invention. It is envisaged that the tolerance specifications for the throttle body during manufacturing are eliminated and for each of the throttle body the flow measurements are carried out at these pre defined strategic points of operation. The proposed invention simplifies the manufacturing process and all the deviations from each throttle body will be recorded by measuring air flow at certain strategic points of the throttle opening. At the final stage of manufacturing process this information is encoded into the throttle body in the form of data matrix which will be decoded and stored in the ECU during the engine or vehicle assembly process.

[0015] In accordance with another embodiment of the invention a method for configuring an electronic control unit (ECU) with air flow characteristics of a throttle body is disclosed. The method for configuring the ECU includes the step of scanning the encoded data matrix on the throttle body by a scanning means in communication with the ECU. The scanning of the encoded data matrix inscribed on the throttle body is done at the time of engine assembly or vehicle assembly or during end of line testing of the vehicle. The ECU decodes the encoded data matrix to obtain air flow characteristics unique to the throttle body being assembled to the engine. The ECU stores the decoded air flow characteristics of the throttle body in a memory. The ECU controls the engine operation based on the decoded air flow characteristics of the throttle body stored in the memory. Based on the position of the throttle, the corresponding air flow rate for the throttle body is determined from the data matrix information stored in the ECU memory. The injection of the fuel to the engine is controlled accordingly to achieve the optimum air fuel ratio for engine operation.
[0016] The measurement of air flow is based on the strategic points of the throttle flap position to yield the maximum benefit and the measurement time required in case of on board sensors is reduced as the ECU is provided with the air flow characteristics of the throttle body. With the air flow characteristics known this data can be decoded during the engine assembly when the throttle body is fitted to the engine and thus ensuring the predefined mass flow characteristics of each throttle body assembly are known to the engine management system it is fitted to. Since the data recording is based on the actual values from the throttle body, the need of maintaining accurate tolerances during manufacturing is not necessary. With the air flow characteristics of the throttle body known, the engine control unit does not require a feedback during engine operation which reduces the need of on board sensor like the oxygen sensor. This leads to the system with open loop to operate efficiently and also meet the target emission norms thus ensuring the reduction of overall system cost.