CN111237109B - Leakage test device for high pressure common rail horizontal cavity fuel injection type injector of piston diesel engine - Google Patents

Abstract

The present invention discloses a leak testing device suitable for a high-pressure common rail transverse cavity oil injection type fuel injector of a piston diesel engine, comprising a heating box for heating a cylinder head fuel injector assembly, a common rail pipe, a high-pressure oil pump connected to the common rail pipe, an oil delivery pump connected to the high-pressure oil pump, and a fuel consumption meter connected to the oil delivery pump and a fuel tank. The cylinder head fuel injector assembly comprises an engine cylinder head and a transverse cavity oil injection type fuel injector arranged on the engine cylinder head. The common rail pipe is connected to the transverse cavity oil injection type fuel injector through a high-pressure oil pipe. A fuel metering unit is arranged on the high-pressure oil pump, and a rail pressure sensor is arranged on the common rail pipe. The present invention is suitable for a leak testing device for a high-pressure common rail transverse cavity oil injection type fuel injector of a piston diesel engine, and can realize low-cost, fast and accurate determination of the leakage point of the transverse cavity oil injection type fuel injector.

Description

Leakage test device for high pressure common rail horizontal cavity fuel injection type injector of piston diesel engine

Technical Field

The invention belongs to the technical field of engines, and in particular to a leak testing device suitable for a high-pressure common rail transverse cavity oil-inlet type fuel injector of a piston diesel engine.

Background Art

Common rail technology and four-valve technology have been widely used in modern diesel engines, making the engine achieve good results in performance and emission limits, and can meet the requirements of non-road T3 and Euro III emission limit regulations. The four-valve structure (two intake and two exhaust) can not only improve the charging efficiency, but also because the fuel injector can be arranged in the center, the porous oil beam is evenly distributed, which can create conditions for good mixing of fuel and air; ultimately improve the quality of the engine mixture, effectively reduce soot particles, HC and NOx emissions and improve thermal efficiency.

The layout of the four-valve engine takes up a lot of layout space because the valves and rocker arms. If an external interface type injector is selected and arranged in the cylinder head of the four-valve engine, due to the limited layout space, the length of the injector is generally designed to be longer to avoid layout interference. Modern diesel engines are compact in structure. Whether in an in-line engine or a horizontally opposed engine, an overly long injector will become a protruding point on the engine boundary, greatly affecting the overall layout space of the engine. In addition, the overly long injector design puts forward higher requirements on the electromagnetic force of the injector solenoid valve and the processing of the injector control rod, which is not conducive to the performance and reliability of the injector. However, due to the difference in structure, the transverse cavity oil injection injector can be compactly arranged on the four-valve cylinder head, so it is widely used in the field of four-valve engines.

Engine lightweighting is becoming an increasingly important goal of engine development. A lighter engine can achieve better vehicle performance and lower fuel consumption. An important way to reduce engine weight is to use new materials. Currently, aluminum alloy cylinder heads have been increasingly used as an important means of reducing diesel engine weight. However, there are two obvious risks faced by aluminum alloy cylinder heads and four-valve diesel engines with transverse cavity fuel injection injectors:

1. The horizontal cavity fuel injection injector and high-pressure connecting pipe are generally located inside the cylinder head, and it is difficult to visually judge whether the assembly is in place and whether the mating surface effectively forms a seal;

2. The high-pressure connecting pipe installed on the aluminum alloy cylinder head is more easily affected by heat factors than on the cast iron cylinder head, because the thermal expansion coefficient of cast iron is generally 9.2-11.8, while the thermal expansion coefficient of aluminum alloy is 23.8. Therefore, after the engine is hot, the aluminum alloy cylinder head is more deformed by heat, and the risk of the high-pressure connecting pipe detaching from the injector is greater, and the risk of leakage is also greater.

In summary, one of the important restrictive factors for the application of cross-cavity fuel injection injectors in four-valve engines is how to ensure the sealing between the high-pressure connecting pipe and the cross-cavity fuel injection injectors and how to quickly and effectively determine whether there is a leakage and determine the leakage point.

Summary of the invention

The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a leak detection device suitable for a high-pressure common rail transverse cavity fuel injection type fuel injector of a piston diesel engine, the purpose of which is to realize low-cost, fast and accurate determination of the leak point of the transverse cavity fuel injection type fuel injector.

In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a leak testing device suitable for a high-pressure common rail transverse-cavity oil-feeding type fuel injector of a piston diesel engine, comprising a heating box for heating a cylinder head injector assembly, a common rail pipe, a high-pressure oil pump connected to the common rail pipe, an oil delivery pump connected to the high-pressure oil pump, and a fuel consumption measuring instrument connected to the oil delivery pump and to a fuel tank, the cylinder head injector assembly comprises an engine cylinder head and a transverse-cavity oil-feeding type fuel injector arranged on the engine cylinder head, the common rail pipe is connected to the transverse-cavity oil-feeding type fuel injector through a high-pressure oil pipe, a fuel metering unit is arranged on the high-pressure oil pump, and a rail pressure sensor is arranged on the common rail pipe.

The oil delivery pump is connected to the motor, and the oil delivery pump is a gear pump.

The fuel metering unit and the rail pressure sensor are electrically connected to the control unit. After the oil delivery pump is running, the test oil from the fuel tank flows through the fuel consumption measuring instrument and the fuel delivery pump in sequence, and then enters the high-pressure oil pump. The pressurized test oil enters the common rail pipe through the high-pressure oil pipe. The control unit performs closed-loop control and adjustment to make the pressure of the common rail pipe reach the target value and remain stable. The excess test oil flows back to the fuel tank through the return oil pipe. If leakage occurs at the connection between the high-pressure oil pipe and the transverse cavity oil-injection injector, the consumption of the test oil can be observed through the fuel consumption measuring instrument.

The leak testing device suitable for the high-pressure common rail transverse-cavity oil-injection type fuel injector of a piston diesel engine also includes a voltmeter electrically connected to the rail pressure sensor. After the fuel consumption meter displays and records the test oil consumption, the oil delivery pump stops running, and the voltage value displayed by the voltmeter is observed. The voltage value displayed by the voltmeter is compared with the standard value to determine whether the oil pressure fluctuation of the common rail pipe exceeds the set range. This result is used as a condition for determining whether the seal between the high-pressure oil pipe and the transverse-cavity oil-injection type fuel injector is effective.

A pressure relief valve is arranged on the common rail pipe, and the pressure relief valve is connected to the oil return pipe.

The leak testing device suitable for high-pressure common rail transverse cavity oil injection type fuel injector of piston diesel engine also includes a temperature control module electrically connected to the heating box, and the temperature control module is used to control the heating box to heat the cylinder head fuel injector assembly and maintain it at the target temperature.

The invention is suitable for a leak testing device of a high-pressure common rail transverse cavity oil-feeding type fuel injector of a piston diesel engine, and can realize low-cost, rapid and accurate determination of the leak point of the transverse cavity oil-feeding type fuel injector.

BRIEF DESCRIPTION OF THE DRAWINGS

This specification includes the following drawings, which show the following contents:

FIG1 is a schematic structural diagram of a leak test device for a high-pressure common rail transverse cavity fuel injection type fuel injector of a piston diesel engine according to the present invention;

FIG2 is a schematic diagram of the structure of a transverse cavity oil-inlet type fuel injector;

The following are marked in the figure: 1. Cylinder head injector assembly; 2. Temperature sensor; 3. Temperature gauge; 4. Power supply stabilizer; 5. Temperature control module; 6. Heating box; 7. High-pressure oil pipe; 8. Oil return pipe; 9. Speed controller; 10. Display device; 11. Motor; 12. Fuel tank; 13. Fuel consumption meter; 14. Fuel pump; 15. High-pressure oil pump; 16. Fuel metering unit; 17. Pressure relief valve; 18. Common rail pipe; 19. Voltmeter; 20. Rail pressure sensor; 21. Control unit.

DETAILED DESCRIPTION

The specific implementation methods of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solution of the present invention and facilitating its implementation.

As shown in FIG1 , the present invention provides a leak testing device suitable for a high-pressure common rail transverse-cavity oil-feeding injector of a piston diesel engine, comprising a heating box 6 for heating a cylinder head injector assembly, a common rail pipe 18, a high-pressure oil pump 15 connected to the common rail pipe 18, an oil delivery pump 14 connected to the high-pressure oil pump 15, and a fuel consumption meter 13 connected to the oil delivery pump 14 and connected to a fuel tank 12. The cylinder head injector assembly comprises an engine cylinder head and a transverse-cavity oil-feeding injector arranged on the engine cylinder head. The common rail pipe 18 is connected to the transverse-cavity oil-feeding injector through a high-pressure oil pipe 7. A fuel metering unit 16 is arranged on the high-pressure oil pump 15, and a rail pressure sensor 20 is arranged on the common rail pipe 18.

Specifically, as shown in FIG1 , the transverse cavity oil-injection type fuel injector is installed on the engine cylinder head, and the transverse cavity oil-injection type fuel injector is connected to the oil outlet of the common rail pipe 18 through the high-pressure oil pipe 7. The oil pump 14 is connected to the motor 11, and the oil pump 14 is a gear pump. The motor 11 is used to drive the oil pump 14 to operate, and the power output end of the motor 11 is connected to the main shaft of the oil pump 14. The motor 11 is electrically connected to the speed controller, and the speed controller is used to control the speed of the motor 11. The high-pressure oil pump 15 is a high-pressure plunger pump, and the oil pump 14 delivers the test oil to the plunger cavity of the high-pressure oil pump 15. The fuel metering unit 16 is an oil metering valve, which is used to measure the amount of test oil flowing through the high-pressure oil pump 15. The high-pressure oil pump 15 is used to pressurize the test oil. The fuel metering unit 16 is integrated on the high-pressure oil pump 15. The test oil in the fuel tank 12 is transported to the inlet of the high-pressure oil pump 15 after passing through the fuel consumption meter 13 and the oil pump 14. Then the fuel flows through the fuel metering unit 16 to reach the oil outlet of the high-pressure oil pump 15. The test oil at the oil outlet of the high-pressure oil pump 15 is transported to the common rail pipe 18 through the high-pressure oil pipe 7. Finally, the test oil is distributed from the common rail pipe 18 to the cross-cavity oil injection type injector.

The rail pressure sensor 20 is used to detect the oil pressure in the common rail pipe 18. The rail pressure sensor 20 outputs a voltage signal to the control unit 21. The fuel metering unit 16 and the rail pressure sensor 20 are electrically connected to the control unit 21. After the oil pump 14 is running, the test oil from the fuel tank 12 flows through the fuel consumption meter 13 and the oil pump 14 in sequence, and then enters the high-pressure oil pump 15. The pressurized test oil enters the common rail pipe 18 through the oil pipe. The test oil in the common rail pipe 18 enters the transverse cavity oil injection type fuel injector through the high-pressure oil pipe 7. The control unit 21 performs closed-loop control and adjustment to make the pressure of the common rail pipe 18 reach the target value and remain stable. The excess test oil flows back to the fuel tank 12 through the return oil pipe 8; if there is a leak at the connection between the high-pressure oil pipe 7 and the transverse cavity oil injection type fuel injector, the consumption of the test oil can be observed through the fuel consumption meter 13.

As shown in FIG1 , since the oil pressure in the common rail pipe 18 is controlled by a closed-loop control system of a fuel metering unit 16 and a rail pressure sensor 20, for safety reasons, in order to prevent the closed-loop control from failing or the fuel metering unit 16 from getting stuck, causing an uncontrollable increase in the test oil pressure, and causing risks such as a burst of the common rail pipe 18, a pressure relief valve 17 is provided on the common rail pipe 18. The pressure relief valve 17 is connected to the oil return pipe 8, and the oil return pipe 8 is connected to the fuel tank 12. The function of the pressure relief valve 17 is that when the system pressure rises to an abnormally high level, the pressure can be released in time after the passage in the valve is opened, so as to ensure that the system oil pressure is maintained within a controllable range and the safety of the system is ensured.

As shown in FIG1 , the leak test device for the piston diesel engine high-pressure common rail transverse cavity oil injection type fuel injector of the present invention further includes a voltmeter 19 electrically connected to the rail pressure sensor. After the fuel consumption meter 13 displays and records the test oil consumption, the oil delivery pump 14 stops running, and the voltage value displayed by the voltmeter 19 is observed, and the voltage value displayed by the voltmeter 19 is compared with the standard value. By calibrating and solidifying the voltage-oil pressure corresponding curve, it is determined whether the oil pressure fluctuation of the common rail pipe 18 exceeds the set range, and this result is used as one of the conditions for determining whether the seal between the high-pressure oil pipe 7 and the transverse cavity oil injection type fuel injector is effective.

As shown in FIG1 , the leak test device for high-pressure common rail transverse cavity oil injection type fuel injector of a piston diesel engine of the present invention further includes a temperature control module 5 electrically connected to a heating box 6, and the temperature control module 5 is used to control the heating box 6 to heat the cylinder head fuel injector assembly and keep it at a target temperature to simulate the actual working state of the engine. The heating box 6 is used to generate heat for heating the cylinder head fuel injector assembly. By controlling the working state of the heating box 6 through the temperature control module 5, the heat generated by the heating box 6 can be effectively controlled, and then the cylinder head fuel injector assembly can be controlled to be kept at a target temperature during the test. A temperature sensor 2 for detecting the temperature of the cylinder head fuel injector assembly is provided at the cylinder head fuel injector assembly, and the temperature sensor 2 is electrically connected to a temperature meter 3, and the temperature meter 3 is used to display the temperature value detected by the temperature sensor 2. During the test, the purpose of heating the cylinder head injector assembly is to simulate the maximum temperature that the engine cylinder head can reach when the engine is in actual working state as the set temperature for heating the heating module, so that the injector, especially the cylinder head, can be fully heated and deformed under this condition. The reason is that the cylinder head assembly, especially the aluminum alloy cylinder head used in the engine material weight reduction, is greatly affected by thermal deformation due to the large thermal expansion coefficient of aluminum alloy. When the cylinder head is deformed by heat, the high-pressure connecting pipe in the cylinder head and the contact point of the injector ball-cone line seal will separate, and this separation will create a risk of leakage.

As shown in FIG1 , during the test, the cylinder head injector assembly is kept in a hot state, and the cylinder head injector assembly is kept at a target temperature. The speed of the motor 11 is adjusted by the PWM control method. The motor 11 drives the oil pump 14 to operate at a transmission ratio of 1:1 (i.e., the motor shaft speed is the same as the main shaft speed of the oil pump 14), so that the oil pipe generates an oil suction vacuum, and the test oil is sucked out of the oil tank 12. The test oil flows through the fuel consumption measuring instrument 13, and the control unit 21 controls the opening of the fuel metering unit 16 in combination with the signal of the rail pressure sensor 20, and a quantitative test oil is sent to the high-pressure oil pump 15. The pressurized test oil enters the common rail pipe 18 through the oil pipe, and the test oil in the common rail pipe 18 passes through the rail pressure sensor 20, and the control unit 21 closes. The ring control adjustment makes the pressure in the common rail pipe 18 reach the target value and remain stable, and the remaining excess test oil flows back to the oil tank 12 through the return oil pipe 8. At this time, the oil pressure of the entire high-pressure system can reach the test target value and stabilize. If the high-pressure system is at the target rail pressure point and there is a leak somewhere in the system, especially at the connection between the high-pressure oil pipe 7 and the cross-cavity oil-injection injector where the leakage risk point is higher, the consumption of the test oil can be observed through the fuel consumption meter 13 to determine whether there is a leakage of the test oil; and through the change of the voltage signal output by the rail pressure sensor 20, it can be determined whether the pressure of the common rail pipe 18 is stable, and then it can be determined whether there is a leakage of the test oil; whether there is a leakage can also be determined by intuitive visual inspection.

Before the test, the temperature control module 5 is used to control the heating box 6 to heat the cylinder head injector assembly and keep it at the target temperature, the system pipelines and electrical connections are assembled, a quantitative test oil is injected into the oil tank 12, the electrical equipment is powered on by the voltage-stabilized power supply, and the fuel consumption meter 13, the voltmeter 19 and various display devices and instruments are checked to see if they show normal values. After checking that the system electrical connection and pipeline connection are OK, the motor 11 is started and the speed of the motor 11 is controlled to the target speed, and the high-pressure oil pump 15 is driven by the motor 11 to reach the target speed. The system pressure of the common rail pipe 18 is observed through the voltmeter 19, the voltage displayed on the voltmeter is observed, and the characteristic curve relationship between the output voltage and the rail pressure solidification of the rail pressure sensor is used to determine whether the system oil pressure reaches the target value and is stable after the system is operating normally. After reaching the target system pressure and stabilizing, observe whether the test oil consumption displayed by the fuel consumption meter 13 exceeds the standard value. This result is used as one of the conditions for determining whether the seal at the connection between the high-pressure oil pipe 7 and the transverse cavity oil injection type injector is effective.

After shutdown, the motor 11, the oil delivery pump 14 and the high-pressure oil pump 15 stop running, and the cylinder head injector assembly is visually inspected for test oil leakage. This result serves as one of the conditions for determining whether the seal at the connection between the high-pressure connecting pipe and the transverse cavity oil-injection injector is effective.

If there is no abnormality, the power can be turned off. After the temperature drops, the test results can be recorded. Based on the test results, it can be comprehensively determined whether the hot leak test results of the horizontal cavity oil-inlet type injector are qualified.

If qualified, record it; if unqualified, determine the leakage point based on the test results and make improvements.

The leak test device of the above structure has the following advantages:

1. The cost of the leak test device is low. Its main components include motor, controller, heating box, oil pump, etc. Compared with other leak test equipment currently used (such as helium detection), the equipment cost is low and easy to obtain;

2. The leak test device is assembled in modules and can be set up at any place at any time. It can be put into testing without complicated debugging. When the leak test device is not needed, the module can be disassembled and used for other purposes without causing cost waste.

3. The leak test device is designed with a heating box and a temperature control device, which is specifically designed for leak testing of the aluminum alloy cylinder head with a high thermal expansion coefficient and lightweight engine at this stage. It can make an intuitive judgment on whether the aluminum alloy cylinder head is deformed by heat and causes leakage of the transverse cavity oil injection injector and the high-pressure connecting pipe;

4. The leak test device can match samples at any stage of engine development. There is no need to redesign expensive tooling due to design changes of injectors, pipelines, and cylinder heads. It is especially suitable for situations where design plans are frequently changed during the engine test development stage.

5. A pressure relief valve is designed at the common rail pipe of the leak test device, which can release pressure in time when the system pressure is too high due to uncontrollable factors during the test to ensure system safety;

6. The leak test device uses a multi-level judgment method for leakage (judgment by fuel consumption meter, judgment by voltmeter, and judgment by visual inspection), which ensures the accuracy of the judgment result;

7. The leak test device can simulate different engine operating conditions for leak testing by adjusting the speed of the driving motor to simulate different engine speeds and defining different target values of the system rail pressure by the controller.

The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention; or the above concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims (4)

1. A leak test device suitable for a piston diesel engine high-pressure common rail transverse cavity fuel injection type fuel injector, characterized in that it comprises a heating box for heating an aluminum alloy cylinder head fuel injector assembly, a common rail pipe, a high-pressure fuel pump connected to the common rail pipe, a fuel delivery pump connected to the high-pressure fuel pump, and a fuel consumption meter connected to the fuel delivery pump and a fuel tank, the cylinder head fuel injector assembly comprises an engine cylinder head and a transverse cavity fuel injection type fuel injector arranged on the engine cylinder head, the common rail pipe is connected to the transverse cavity fuel injection type fuel injector through a high-pressure fuel pipe, a fuel metering unit is arranged on the high-pressure fuel pump, and a rail pressure sensor is arranged on the common rail pipe; The fuel metering unit and the rail pressure sensor are electrically connected to the control unit. After the oil delivery pump is running, the test oil from the fuel tank flows through the fuel consumption measuring instrument and the fuel delivery pump in sequence, and then enters the high-pressure fuel pump. The pressurized test oil enters the common rail pipe through the high-pressure fuel pipe. The control unit performs closed-loop control and adjustment to make the pressure of the common rail pipe reach the target value and remain stable. The excess test oil flows back to the fuel tank through the return pipe. If a leak occurs at the connection between the high-pressure fuel pipe and the transverse cavity fuel injection type injector, the consumption of the test oil can be observed through the fuel consumption measuring instrument. The leak testing device suitable for the high-pressure common rail transverse-cavity oil-injection type fuel injector of a piston diesel engine also includes a voltmeter electrically connected to the rail pressure sensor. After the fuel consumption meter displays and records the test oil consumption, the oil delivery pump stops running, and the voltage value displayed by the voltmeter is observed. The voltage value displayed by the voltmeter is compared with the standard value to determine whether the oil pressure fluctuation of the common rail pipe exceeds the set range. This result is used as a condition for determining whether the seal between the high-pressure oil pipe and the transverse-cavity oil-injection type fuel injector is effective. 2. The leak testing device suitable for a high-pressure common rail transverse-cavity fuel injection type fuel injector of a piston diesel engine according to claim 1 is characterized in that the oil delivery pump is connected to the motor and the oil delivery pump is a gear pump. 3. The leak testing device suitable for a high-pressure common rail transverse-cavity oil-injection type fuel injector of a piston diesel engine according to claim 1, characterized in that a pressure relief valve is arranged on the common rail pipe, and the pressure relief valve is connected to the oil return pipe. 4. A leak testing device suitable for a high-pressure common rail transverse-cavity fuel injection type fuel injector of a piston diesel engine according to any one of claims 1 to 3, characterized in that it also includes a temperature control module electrically connected to the heating box, and the temperature control module is used to control the heating box to heat the cylinder head injector assembly and maintain it at a target temperature.