Claims:We claim:
1. A testing apparatus (100) to test an injector (110), said testing apparatus (100) comprising:
-a first intake path (102) to receive air, said air being guided to an inlet (108) of said injector (110);
-a first transducer (104) disposed in said intake path (102) to measure a first parameter of said air passing through;
-a first port (106) connectable to said inlet (108) of said injector (110) to guide received air to said injector (110);
-a second intake path (112) connectable to a return path (114) of said injector (110) to receive leaked air from said injector (110);
-a second transducer (116) disposed in said second intake path (112) to measure a second parameter of said air passing through;
-a controller (118) to read said first parameter and said second parameter to determine whether said injector (110) is defective or not
2. A testing apparatus (100 according to claim 1 wherein said controller (118) controls an actuator, said actuator connectable to said injector to control a solenoid in said injector (110)
3. A testing apparatus (110) according to claim 1 wherein said first transducer (104) is a pressure sensor
4. A testing apparatus according to claim 1 wherein said second transducer (116) is a pressure sensor
5. A testing apparatus according to claim 1 wherein said first transducer (104) is a flow meter
6. A testing apparatus according to claim 1 wherein said second transducer (116) is a flow meter
7. A method to test an injector (110) said method comprising the steps:
-receiving air through a first intake path (102) and guiding the air to an inlet (108) of said injector
-receiving air from return path (114) of said injector (110) through a second intake path (112)
-reading a first parameter from a first transducer (104) disposed in aid first intake path (102)
-reading a second parameter from a second transducer (116) disposed in said second intake path (112)
-determining whether said injector (119) is defective or not by analyzing said first parameter and said second parameter
8. A method to test an injector (100) for leakage according to claim 7, wherein a solenoid in said injector (100) is energized for a predefined time to increase flow of air from said inlet (108) of said injector (100) to said return path (114) of said injector (100)
9. A method to test an injector (100) for leakage according to claim 7, wherein said first parameter is read from said first transducer (104) before said solenoid is de-energized.
10. A method to test an injector (100 for leakage according to claim NNN, wherein said second parameter is read from said second transducer (116) before said solenoid is de-energized.
11. A method to test an injector (100) for leakage according to claim 7, wherein said injector (100) is determined as defective if ratio of said second parameter to said first parameter exceeds a pre-defined threshold
12. A method to test an injector (100) for leakage according to claim 7, wherein said second parameter has a known relationship to said first parameter.
13. A method to test an injector (100) for leakage according to claim 7, wherein if said injector (100) is determined as defective, a visual indication is provided.
, Description:Field of the invention:
[0001] This invention relates to the field of testing a fuel injector. The invention relates in particular to test leakage of the injector.

Background of the invention:
[0002] The US patent 7316153B2 discloses a method for ascertaining the leakage from injection systems to test the tightness of an injection system, in particular of an injector or of an injection valve. In the prior art the measurement are performed by introducing a test fluid into a measurement chamber; varying the pressure in the injection system (30);detecting the motion of a piston, and evaluating the measurement signals furnished by the detection device, for each pressure.
[0003] The prior art DE 102004055575 discloses a method and an apparatus for testing leakage in a fuel injection valve of an internal combustion engine with at least one actuator by which a connection of the fuel injection valve is controlled indirectly. The temperature of the actuator is measured to detect about the leakage.

Brief description of the accompanying drawings:
[0004] An embodiment of the disclosure is described with reference to the following accompanying drawing,
[0005] Fig. 1 illustrates a testing apparatus to test an injector

DETAILED DESCRIPTION OF THE EMBODIMENTS
[0006] Shown in fig. 1 is a testing apparatus to test an injector 110. The test will help specifically to determine whether the leakage in the injector is above a predefined threshold. If the leakage is above the predefined threshold, then the injector is determines as defective. Also if the injector nozzle is stuck in an open state, the testing apparatus detects it.
[0007] The testing apparatus 100 shown in fig. 1 comprises a first intake path 102 to receive air; a first transducer 104 disposed in said first intake path 102 to measure a first parameter of said air passing through; a first port 106 connectable to inlet 108 of injector 110 to guide received air to said injector 110; a second intake path 112 connectable to a return path 114 of injector 110 to receive leaked air from injector 112; a second transducer 116 disposed in second intake path 112 to measure a second parameter of air passing through; a controller 118 to read first parameter and second parameter to determine whether injector 110 is defective or not. The testing apparatus 100 also comprises a display 120 to inform the user about the test result.
[0008] The testing apparatus 100 receives compressed air through a hose which is connectable to the intake path 102. The air and compressed air have same meaning in this document.
[0009] The controller 118 comprises a microcontroller, memory, input output devices, ports etc. The ports are used to control actuators and to read the signals from the first and second transducers 104, 116. The actuator may form the part of the controller 118 or may be outside the controller 118. The actuator may contain a driver circuit to control a solenoid in the injector 110. The actuator is connected to the solenoid in the injector 110. The controller 118 can energize or de-energize the solenoid in the injector through the actuator. The energizing of solenoid in the injector results in the attraction of the armature in the injector thereby increasing the volume of the passage from the inlet to the return path in the injector. The increased volume of the passage from the inlet to the return path in the injector helps smooth passage of air from the inlet to the return path of the injector thereby increasing the accuracy of the tests.
[0010] The first and the second transducers 104, 116 could be pressure sensors. Also it is possible that the first and the second transducers could be flow meters.
[0011] The display 120 could be an alphanumeric display which informs the user about the test result. The test result may be in the form of a text displayed as “Passed” or “Failed” to indicate that the injector is functioning well or the injector is defective. The display 120 could also be a simple LEDs to indicate the test result. There may be green LED to indicate that the injector is good. There may be red LED to indicate that the injector is defective.
[0012] Under the actual condition of the injector operations, i.e. when the engine is running, the fuel which is under high pressure enters the injector through the inlet. The pressurized fuel enables the nozzle in the injector to lift and the fuel is injected into the cylinder of the engine. Part of the fuel returns to the fuel tank through the return path 114. The quantity of fuel which is injected and the quantity of fuel which returns through the return path will have a known relationship. A valve sealing which is not shown allows fuel to flow to return path. The valve sealing is designed in such a way that required ratio is maintained between the quantity of fuel which is injected and the quantity of fuel which returns through the return path. If the valve sealing degrades or the valve sealing is defective, then the quantity of fuel flowing through the return path will increase. This amounts to less fuel being injected into the cylinder. This will lead to deterioration of the engine performance and may damage the engine. To avoid such a situation, it becomes very important that the valve sealing is proper.
[0013] To check whether the valve sealing is proper or not, the testing apparatus is used.
[0014] A method to test the injector 110 comprises the steps: receiving air through a first intake path 102 and guiding the air to an inlet (108) of said injector; receiving air from return path 114 of said injector 110 through a second intake path 112; reading a first parameter from a first transducer 104 disposed in aid first intake path 102;reading a second parameter from a second transducer 116 disposed in said second intake path 112;determining whether said injector 119 is defective or not by analyzing said first parameter and said second parameter
[0015] Before the beginning of the test, the first intake path 102 is connected to an external air compressor, which is not part of the testing apparatus, through a hose. The second intake path 112 is connected to a return path 114 of injector through a hose. The first port 106 is connected to the inlet 108 through a hose. Once these three connections are made, the testing apparatus is ready to test the injector.
[0016] The method to conduct the testing is explained below.
[0017] Once the above connections are made the air starts flowing into and out of the testing apparatus 100. The compressed air is received through the intake path 102. The compressed air travels to the injector 110 through the first port 106 and through the inlet 108 of the injector 110. As the needle in the injector 110 remains closed the air will not escape through the nozzle holes of the injector. Part of the air gets trapped in the injector and part of the air passes through the valve sealing in the injector and then flows into the return path 114 of the injector. The compressed air enters the second intake path 112 which is connected to the return path 114 of the injector 110. Then the air escapes into atmosphere through a throttle 122.
[0018] The user presses a start button to start the testing. The controller keeps reading the first parameter from the first transducer 104 and the second parameter from the second transducer 116. In one embodiment these transducers are pressure sensors. The first and second parameters are pressure values as read by first pressure sensor and second pressure sensor respectively. The controller reads pressure value P1 from first pressure senor 104 and pressure value P2 from second pressure sensor 116 respectively. The P1 and P2 are stored. The controller may read and store a set of P1 and P2 values within a given time window. Once a set of values of P1 and P2 are available, the controller computes mean of P1 and P2 values, represented as p1 and p2. The mean values are used to increase the accuracy of the test results. The ratio of p2 to p1 i.e. p2/p1, is pre-known as the injector is designed with known spring forces and the valve sealing factor in the injector 110. Also the threshold for the deviation of the ratio of p2 to p1 is stored in the controller 118. The controller 118 computes the ratio of p2 to p1. The controller checks whether the ratio of p2 to p1 is within a pre-defined threshold. If the ratio is within the threshold, the controller displays the test result to the user through the display as “Passed” otherwise as “Failed”.
[0019] It is possible that pressure of the incoming air may have to be changed depending upon the type of injectors. For example, for a first type of injectors, the best results may be obtained at 4 bar pressure of the incoming air. For a second type of injectors, the best results may be obtained at 6 bar pressure of incoming air.
[0020] It is possible that the ratio of p2 to p1 varies depending upon type of injectors. It is possible that the user enters this ratio through a switch. It is also possible that the user enters the threshold to be used to check for the defective injectors.
[0021] To increase the accuracy of the testing, before the start of the test, the controller 118 may activate the actuator which in turn energizes the solenoid in the injector 110. Energizing the solenoid results in movement of the armature within the injector resulting in increased passage for the compressed air to move from the injector body to the return path. As the passage is increased, more air reaches the valve seating and the return path. This will clean up the passage of any residual fuel stuck to the valve sealing or in the return path thereby increasing the accuracy of P2 values.
[0022] The energizing of solenoid is done taking into consideration the injector specification for maximum on period of the solenoid. The solenoid is energized for a specified time T1, the values of P1 and P2 are read and stored, then the solenoid is de-energized for a specified time T2. These steps are repeated until a pre-defined number of P1 and P2 readings are stored. The computation of mean values and determining whether the test passed or failed is displayed as explained earlier.
[0023] The testing apparatus 100 can additionally determine whether the injector nozzle is stuck in open state. The open state is the one where the nozzle is held in lifted position permanently thereby uncovering the nozzle holes. If the injector is stuck in open position, then maximum air escapes through the nozzle holes and very little air reaches the return path. This state will influence p1 and p2. By analyzing the p1 and p2, the controller 118 determines whether the injector is stuck permanently in open state.
[0024] The disclosure provides a testing apparatus where the injector is tested conveniently without removing the same from the vehicle. The testing apparatus is connectable easily to the injector by hoses.
[0025] As air is used to test the injector, the testing becomes easy to handle. There is no handling of fuel during the testing. The testing apparatus uses known components like pressure sensors, controller, and actuator which are easily available, leading to simple construction.
[0026] The testing apparatus is simple to use, cost effective and provides useful results. The testing apparatus detects whether the injector valve seating is defective or the injector is stuck in an open state. This is achieved by simple analysis of the readings p1 and p2
[0027] The testing apparatus can handle different types of injectors. The testing apparatus is made configurable by the user. The testing apparatus provides options to enter the expected ratio between p1 and p2. It also provides option to enter the value for the threshold using which the test is determined as passed or failed.