FIELD OF INVENTION:

The invention relates to a method to detect high pressure leakage of fluid in a fuel injection pump.

BACKGROUND OF THE INVENTION:

Detecting leakage of fluid in a pump body is known in prior arts. The prior art GB2328750A discloses one such method. In a method for testing an internal combustion engine for leak-tightness, the heat arising at a leak due to the exit of a pressurized liquid from a system is detected using thermal imaging cameras or thermocouples. By monitoring the temperature at probable leakage points in the pump body, the leakage of the fluid into the pump body is detected.

OBJECT OF THE INVENTION:

The invention proposes a test setup to test a pump to detect the leakage of the fluid in the pump body. The test detects a defective pump. The pump is said to be defective if the fluid being pressurized in the pump leaks into the pump body.

The fluid may be fuel or oil used in a combustion engine. The pump is a high pressure pump used to pump oil, fuel etc.

ADVANTAGES OF THE INVENTION:

The proposed invention provides a simple test setup to detect a defective pump. The test setup is adapted to receive the pump without any modifications. The test setup has a fluid inlet line which can be easily connected to the inlet of the pump. Also the test setup has a fluid return line which can be easily connected to the return path of the pump. The temperature sensors are located in the fluid inlet line and the fluid return line. The test setup also comprises a simple controller which may be in the form of a microcontroller controlled device or a personal computer.

The pump under test is easily connectable to the test setup without any modifications. The test is run as automated test once the pump is connected to the test setup. The test setup runs the steps automatically and detects a defective pump.

BRIEF DESCRIPTION OF THE DRAWINGS:-

FIG. 1 shows a schematic of the invention

DETAILED DESCRITPION OF THE INVENTION:

The present invention is described in the preferred embodiment as follows:-

FIG. 1 shows a schematic of the test setup according to the invention. The schematic is only a symbolic representation. The test setup comprises a fluid inlet line 12, a fluid return line 14 and a controller 16. One end of the fluid inlet line is connected to a feed pump 13, which pumps the fluid from tank 18 storing the fluid. The other end of the fluid inlet line 12 is connectable to the inlet 19 of the pump 20 which is to be tested. One end of the fluid return line 14 is connected to the tank 18 and the other end of the fluid return line 14 is connectable to the return path 22 of the pump 20 which is to be tested. The controller 16 controls an actuator 24 which starts/stops pressurizing the fluid in the pump 20.

A first temperature sensor 26 is located in the fluid inlet line 12 and a second temperature sensor 28 is located in the fluid return line 14.

The steps to test the pump are explained below:

The pump 20 is placed on a firm platform which may be part of the test setup or may be an independent unit. The inlet 19 of the pump is connected to the fluid inlet line 12. The return path 22 of the pump is connected to the fluid return line 14. The outlet 34 of the pump 20 delivers the fluid at high pressure to the high pressure line 36. A pressure sensor at the high pressure line provides the pressure value.

The cam 38 of the pump 20 is connected to the actuator 24 which is controlled by the controller.

Once all the connections are made, the controller 16 is initiated by running the program in the controller.

The controller 16 activates the actuator 24 which starts to drive the cam 38 of the pump 20. The driving of the cam 38 starts the operation of the pump 20. The pump 20 sucks the fluid from the inlet sidel2 and pressurizes it. The controller 16 keeps driving the actuator 24, thereby test pump 20 pumps the fluid at high pressure into delivery line 36.

Once the pressure of the pressurized fluid reaches a pre-determined value, the controller 16 reads the temperature from the first and the second temperature sensors, i.e 26 and 28, these temperatures are referred as Tin and Tout respectively. The controller compares both to find out the difference in the temperatures.

If the pump is not defective, the difference between the Tout and Tin is within a predefined range.

If the pump 20 is defective, the fluid which is under high pressure in the pump 20 starts leaking into the pump body 39. This may be because of the fault in the sealing, or the tolerances in the components of the pump 20 being beyond the permissible values.

Once the fluid starts leaking into the pump body 39, the temperature of the pump body 39 increases. This heat is absorbed by the fluid in the pump 20 and the temperature of the fluid increases. But the increase in the temperature in the fluid is more on the fluid in the fluid return path 14 than the fluid in the inlet path 12. This is because of the reason that the heat is generated due to pump body leak carried away by excess fluid which escapes from the fluid return path 14. The flow from the feed pump 13 is always maintained at the pump inlet 19, hence the fluid escaping from the pump return path is more prone for absorbing heat from the pump body and hence increased temperature in the fluid return path 14.

Hence when the pump 20 is defective, because of the leakage of the fluid into the pump body 39 the temperature of the fluid in the fluid return line 14 is higher than the temperature of the fluid in the fluid inlet line 12 by a threshold.

The below relationship shows a defective pump:

Tout - Tin > threshold Where Tout is temperature of the fluid in fluid return line 14, Tin is the temperature of the fluid in the fluid inlet line 12 and threshold is a predefined value. The threshold may be influenced by factors like type of the pump, the pressure generated by the pump, type of fluid etc.

The controller 16 determines the temperature difference between the Tout and Tin and determines whether the pump is a defective pump or a non-defective pump based on the difference in the temperatures. If the pump is determined as defective, the controller 16 generates a warning 40. The warning may be an audio signal or an illumination of a lamp, typically a red lamp with display on the computer screen. If the pump is determined to be non-defective, a green lamp may be illuminated to indicate that the test is successful and the pump is non defective.

WE CLAIM:

1. A test setup to test a pump 20 for leakage of fluid in the pump body 39, the said test setup comprising:

- A first temperature sensor 26 located in the fluid inlet line of the test setup to monitor the temperature of the fluid entering into the pump

- A second temperature sensor 28 in the fluid return line 14 to monitor the temperature of the fluid being returned to a tank 18

- A controller 16 to operate the pump, the said controller 16 adapted to detect a leakage of the fluid in the pump body 39 by analyzing the temperature of the fluid entering into the pump and the temperature of the fluid being returned to the tank

2. A test setup according to claim 1 and 2 wherein the controller detects the pump as faulty if the temperature of the fluid returning to the tank is greater than the temperature of the incoming fluid by a given threshold.

3. A test setup according to claim 1 and 2 wherein the controller 16 generates a warning 40 if the pump is defective.

4. A test setup according to claim 1 and 2 wherein the warning is an audio signal

5. A test setup according to claim 1 and 2 wherein the warning is in the form of illuminating a lamp with display on computer screen

6. A method to determine leakage of fluid in a pump body, the said method comprising the steps:

- during operation of the pump, monitoring the temperature of the fluid entering into the pump and monitoring the temperature of the fluid being returned to a tank declaring the pump as defective if the temperature of the fluid returning to the tank is greater than the temperature of the incoming fluid by a given threshold.