A test method for determining jet fusion during multiple injections in a high-pressure common rail system

Abstract

This invention provides a test method for determining injection fusion in multiple injections of a high-pressure common rail system, comprising the following steps: S1. Constructing a high-pressure common rail system injection pattern test system to test the injection pattern of two injections: pre-injection + main injection; S2. Constructing a high-speed photography direct-view test system for the injection process of the high-pressure common rail system to test the spray development characteristics under injection intervals; S3. Processing the images of the spray development process of multiple injections of the high-pressure common rail system, and repeating the spray development characteristic test until the fuel sprays of the two injections merge. The test method for determining injection fusion in multiple injections of a high-pressure common rail system described in this invention employs a spray visualization test method, obtaining the actual development process of real fuel spray in the cylinder, which can accurately determine whether actual fuel spray fusion has occurred in the cylinder, solving the problem of misjudgment of injection fusion based on control signals and injection pattern curves.

Description

Technical Field

[0001] This invention belongs to the field of multiple injection in high-pressure common rail systems for diesel engines, and in particular relates to a test method for determining injection fusion in multiple injections of a high-pressure common rail system. Background Technology

[0002] One major advantage of the high-pressure common rail system over other fuel supply systems is its ability to perform multiple injections within a single engine cycle. This multiple injection technology effectively controls NO in diesel engines. X It reduces particulate matter emissions, decreases combustion noise, and improves the overall economy and power of the machine.

[0003] Due to various delays during the injection process (especially the opening and closing delays of the needle valve), if the interval between two adjacent injections is too small during multiple injections, the second injection may begin before the first injection has finished, causing the two injections to merge into a single injection. This injection fusion phenomenon prevents multiple injections from being achieved, leading to a deviation from the target injection strategy and worsening the combustion process. Therefore, when performing multiple injections, it is essential to determine whether injection fusion has occurred between two adjacent injections. Only when the set injection interval is greater than the injection interval at which injection fusion occurs can multiple injections be achieved.

[0004] The determination of injection fusion cannot be based solely on control signals and injection pattern curves. Even if the control system sets an injection interval between two injections, the actual fuel spray in the cylinder may have already fused due to the injection delay. Similarly, even if injection fusion appears in the injection pattern curve, the actual spray in the cylinder may not have fused due to the injection delay. Therefore, it is necessary to use spray visualization testing methods to visually observe whether adjacent sprays have merged, determine the critical injection interval for spray fusion, and set a reasonable injection interval in the control system to ensure that injection fusion does not occur during multiple injection processes, thus achieving multiple injections. Summary of the Invention

[0005] In view of this, the present invention aims to propose a test method for judging the occurrence of injection fusion in multiple injections of a high-pressure common rail system, so as to solve the problem of misjudgment of injection fusion by control signals and injection pattern curves.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A test method for determining jet fusion during multiple injections in a high-pressure common rail system includes the following steps:

[0008] S1. Build a high-pressure common rail system injection pattern test system, and conduct two injection pattern tests on this system: pre-injection + main injection, until the injection pattern curves of pre-injection and main injection are exactly connected. Use the injection interval at this time as the injection fusion reference injection interval.

[0009] S2. Construct a high-speed photography direct-shot test system for the injection process of the high-pressure common rail system. Fill the constant-volume combustion bomb of the system with background gas, adjust the back pressure inside the constant-volume bomb to be consistent with the back pressure of the fuel injection law test system, and keep the test conditions consistent with the fuel injection law test. Set the injection interval as the injection fusion reference injection interval, and test the spray development characteristics under this injection interval.

[0010] S3. Process images of the multiple injection spray development process of the high-pressure common rail system to confirm whether the pre-injection and main injection fuel sprays have merged at the reference injection interval. If they have not merged, continue to reduce the injection interval and repeat the spray development characteristic test until the fuel sprays of the two injections merge. The injection interval at this time is the critical injection interval for injection fusion. At this time, it is determined that the multiple injections have actually merged.

[0011] Furthermore, in step S1, the fact that the pre-injection and main injection curves are exactly connected means that the end point of the pre-injection curve coincides with the beginning point of the main injection curve.

[0012] Furthermore, in step S1, the high-pressure common rail system injection pattern test system includes a single-shot injector. The outlet of the fuel tank is connected to the inlet of the fuel tank after passing through a valve, a coarse filter, a fine filter, a high-pressure fuel pump, a rail pressure regulating valve, a common rail pipe, and an overflow valve. A temperature controller is also installed on the fuel tank. A pressure gauge is installed on the pipeline between the fine filter and the high-pressure fuel pump. A pressure gauge is installed at one end of the common rail pipe, and the other end is connected to the input end of the fuel tank through an electronically controlled injector. The electronically controlled injector is located above the single-shot injector. The ECU is connected to the pressure gauge, the rail pressure regulating valve, the pressure gauge, the common rail pipe, the electronically controlled injector, and the temperature controller to achieve overall control of the entire system.

[0013] Furthermore, the high-speed photography direct-shot test system for the high-pressure common rail system injection process in step S2 includes an ECU and a high-pressure oil pump. The high-pressure oil pump delivers liquid from the oil tank to the electronically controlled injector via the oil rail. A constant-volume combustion bomb is located below the electronically controlled injector, and a heating device is installed inside the constant-volume combustion bomb. Quartz windows are located on opposite sides above the constant-volume combustion bomb, with a light source and a high-speed camera on the outside of the quartz windows respectively. The spray generated by the electronically controlled injector is located on the horizontal plane of the quartz windows. The high-speed camera transmits the captured images to the computer and the ECU respectively. The constant-volume combustion bomb pipeline is connected to the gas cylinder, and a pressure control valve is installed on this pipeline. The pressure control valve and the heating device are both connected to the microcontroller. The ECU is also connected to the high-pressure oil pump, the oil rail, the electronically controlled injector, and the computer respectively to complete the data acquisition and control of the entire system.

[0014] Furthermore, in step S2, before conducting the spray visualization test, the electronically controlled fuel injector is first processed by drilling a single hole with the same diameter as the original hole at the center of the nozzle tip to seal the original spray hole of the electronically controlled fuel injector.

[0015] Furthermore, in step S2, the background gas is sulfur hexafluoride, which has a density five times that of air, and the background temperature is set to 303K; the injection interval set in the electronic control system between the end of the pre-injection and the start of the main injection is the time interval between the end of the pre-injection pulse width and the start of the main injection pulse width.

[0016] Furthermore, in step S3, when processing the spray development process image, the presence or absence of spray fusion is determined by comparing and analyzing whether the pre-spray jet and the main spray jet in the spray development image are interrupted.

[0017] Compared with existing technologies, the test method for determining jet fusion during multiple injections in a high-pressure common rail system described in this invention has the following advantages:

[0018] (1) The test method for judging the injection fusion of multiple injections in the high-pressure common rail system described in this invention adopts the spray visualization test method, which obtains the actual development process of real fuel spray in the cylinder. It can accurately judge whether the actual fuel spray in the cylinder has injection fusion, and solves the problem of misjudging injection fusion by control signal and injection pattern curve. It can be used to guide the reasonable setting of injection interval in the control system to ensure that injection fusion does not occur in the multiple injection process, so as to realize multiple injection. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0020] Figure 1This is a schematic diagram of the high-pressure common rail system injection pattern test system according to an embodiment of the present invention;

[0021] Figure 2 This is the multiple injection fuel injection pattern curve under the reference injection interval described in the embodiments of the present invention;

[0022] Figure 3 This is a schematic diagram of the high-speed photography direct-shot test system for the high-pressure common rail system jetting process described in an embodiment of the present invention;

[0023] Figure 4 This is a diagram illustrating the development characteristics of multiple sprays at a reference spray interval as described in an embodiment of the present invention.

[0024] Figure 5 This diagram illustrates the development characteristics of multiple sprays at the critical spray interval as described in an embodiment of the present invention.

[0025] Explanation of reference numerals in the attached figures:

[0026] 1-Fuel tank; 2-Valve; 3-Coarse filter; 4-Motor; 5-High-pressure oil pump; 6-Rail pressure regulating valve; 7-Pressure gauge 1; 8-Fine filter; 9-Pressure gauge 2; 10-Common rail; 11-Relief valve; 12-Electrically controlled fuel injector; 13-Single injection device; 14-Temperature controller; 15-Computer; 16-Pressure control valve; 17-Exhaust valve; 18-Microcontroller; 19-Fuel rail; 20-Light source; 21-Gas cylinder; 22-Quartz window; 23-High-speed camera; 24-Constant volume incendiary bomb; 25-Heating device. Detailed Implementation

[0027] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0028] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0030] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] A test method for determining jet fusion during multiple injections in a high-pressure common rail system, such as... Figures 1 to 5 As shown, the process includes the following steps: S1. Constructing a high-pressure common rail system injection pattern test system, such as... Figure 1 As shown, a two-stage injection pattern test (pre-injection + main injection) was conducted on this system. The injection interval between the end of the pre-injection and the start of the main injection was continuously reduced until the injection pattern curves of the pre-injection and main injection were exactly connected. Figure 2 As shown, the injection interval at this time is 0.4ms, and the injection interval at this time is used as the reference injection interval for injection fusion.

[0032] The statement that the pre-injection and main injection fuel injection curves are exactly connected means that the end point of the pre-injection curve coincides with the beginning point of the main injection curve.

[0033] The high-pressure common rail system injection pattern test system includes a fuel tank 1, valve 2, coarse filter 3, motor 4, high-pressure fuel pump 5, rail pressure regulating valve 6, pressure gauge 1 7, fine filter 8, pressure gauge 2 9, common rail pipe 10, overflow valve 11, electronically controlled injector 12, single-shot injector 13, temperature controller 14, and ECU. The outlet of fuel tank 1 connects to the inlet of fuel tank 1 after passing through valve 2, coarse filter 3, fine filter 8, high-pressure fuel pump 5, rail pressure regulating valve 6, common rail pipe 10, and overflow valve 11. A temperature controller is also installed on fuel tank 1. The temperature controller 14 and the high-pressure oil pump 5 are also connected to the motor 4. A pressure gauge 7 is installed on the pipeline between the fine filter 8 and the high-pressure oil pump 5. A pressure gauge 9 is installed on one end of the common rail pipe 10, and the other end is connected to the input end of the oil tank 1 through the electronic fuel injector 12. The electronic fuel injector 12 is located above the single injection device 13. The ECU is connected to the pressure gauge 7, the rail pressure regulating valve 6, the pressure gauge 9, the common rail pipe 10, the electronic fuel injector 12, and the temperature controller 14 to realize the overall control of the entire system.

[0034] S2. Build a high-speed photography direct shooting test system for the injection process of the high-pressure common rail system. Introduce background gas into the constant volume combustion bomb through the air intake system. Adjust the back pressure inside the constant volume bomb to be consistent with the back pressure of the fuel injection law test system. Keep the test conditions consistent with the fuel injection law test. Set the injection interval as the injection fusion reference injection interval. Test the spray development characteristics under this injection interval.

[0035] The high-pressure common rail system injection process high-speed photography direct-view test system includes an ECU, fuel tank 1, motor 4, high-pressure fuel pump 5, electronically controlled fuel injector 12, computer 15, pressure control valve 16, exhaust valve 17, microcontroller 18, fuel rail 19, light source 20, gas cylinder 21, quartz window 22, high-speed camera 23, constant-volume incendiary bomb 24, and heating device 25. The high-pressure fuel pump 5 delivers liquid from the fuel tank 1 to the electronically controlled fuel injector 12 via the fuel rail 19. A constant-volume incendiary bomb 24 is located below the electronically controlled fuel injector 12, and a heating device 25 is installed inside the constant-volume incendiary bomb 24. Quartz windows 22 are located on opposite sides above the constant-volume incendiary bomb 24. A light source 20 is installed outside one quartz window, and the other... A high-speed camera 23 is mounted on the outside of the quartz window 22, and the spray generated by the electronic fuel injector 12 is positioned on the horizontal plane of the quartz window 22, facilitating image acquisition by the high-speed camera 23. The high-speed camera 23 transmits the captured images to the computer 15 and the ECU. The constant-volume combustion bomb 24 is also connected to the outside via two pipelines. One pipeline is equipped with an exhaust valve 17, and the other pipeline is connected to the gas cylinder 21. A pressure control valve 16 is installed on the other pipeline. The pressure control valve 16 and the heating device 25 are both signal-connected to the microcontroller 18. The ECU is also signal-connected to the high-pressure fuel pump 5, the fuel rail 19, the electronic fuel injector 12, and the computer 15, respectively, for data acquisition and control of the entire system. The heating device 25 can be any device or mechanism capable of heating the fuel inside the constant-volume combustion bomb 24.

[0036] In order to capture the development characteristics of single-beam oil mist, before conducting the spray visualization test, the electronically controlled fuel injector 12 was first processed, and a single hole with the same diameter as the original hole was drilled at the center of the nozzle tip. During the test, a specific tooling was used to seal the original nozzle of the electronically controlled fuel injector 12, allowing only the fuel spray from the center nozzle to be injected into the constant volume combustion bomb, thereby realizing the test of the development process of single-beam spray.

[0037] To ensure that the back pressure inside the constant-volume combustion chamber matches the back pressure of the fuel injection pattern testing system, the background gas used is sulfur hexafluoride, which has a density five times that of air, and the background temperature is set to 303K. The injection interval set in the electronic control system between the end of the pre-injection and the start of the main injection is the time interval between the end of the pre-injection pulse width and the beginning of the main injection pulse width. Based on the calculation formula for the adiabatic isentropic compression process of a diesel engine and the ideal gas law, the same injection environment as the fuel injection pattern testing experiment is simulated by adjusting the background gas pressure inside the constant-volume combustion chamber.

[0038] S3. Process images of the multiple injection spray development process of the high-pressure common rail system to confirm whether the pre-injection and main injection fuel sprays have merged at the reference injection interval. If they have not merged, continue to reduce the injection interval and repeat the spray development characteristic test until the fuel sprays of the two injections merge. The injection interval at this time is the critical injection interval for injection fusion. At this time, it is determined that the multiple injections have actually merged.

[0039] When processing images of the spray development process, the presence or absence of spray interruption between the pre-spray jet and the main spray jet is determined by comparing and analyzing the images.

[0040] In this embodiment, the injection strategy employs a multi-injection process consisting of pre-injection and main injection. The injection interval between the end of pre-injection and the start of main injection is set to 0.4 ms in the electronic control system. Other injection parameters remain consistent with the injection pattern test conditions. A test of the spray development characteristics of the high-pressure common rail system with multiple injections is conducted to obtain images of the actual spray development process. The spray images under this injection interval are analyzed. Figure 4 As shown, the last image with continuous oil jets during the pre-spray process is number 2, which is the image showing the end of the pre-spray. The first image with continuous oil jets after the pre-spray is number 5, which is the image showing the start of the main spray. There are a total of 4 images between the end of the pre-spray and the start of the main spray, and the time interval between two adjacent images is 0.1ms. Therefore, the actual spray interval between the end of the pre-spray and the start of the main spray is 0.3ms. At this time, although the pre-spray and the main spray have merged in the fuel injection curve, the time spray has not merged.

[0041] Continue to reduce the spray interval to 0.3 ms, and continue the high-pressure common rail system multiple-spray spray development characteristic test according to the above method. Obtain images of the actual spray development process of multiple sprays, and analyze the spray images under this spray interval, such as... Figure 5 As shown, there is no interruption between the pre-spray and the main spray, meaning they are perfectly blended. Therefore, with a spray interval of 0.3ms, it can be determined that multiple sprays have merged, and the multiple spray strategy has not been implemented.

[0042] The test method for determining injection fusion in multiple injections of a high-pressure common rail system described in this solution adopts a spray visualization test method, which obtains the actual development process of real fuel spray in the cylinder. It can accurately determine whether injection fusion has occurred in the actual fuel spray in the cylinder, and solves the problem of misjudging injection fusion by control signals and injection pattern curves. It can be used to guide the reasonable setting of injection interval in the control system to ensure that injection fusion does not occur in the multiple injection process, so as to achieve multiple injection.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A test method for determining jet fusion during multiple injections in a high-pressure common rail system, characterized in that: Includes the following steps: S1. Build a high-pressure common rail system injection pattern test system, and conduct two injection pattern tests on this system: pre-injection + main injection, until the injection pattern curves of pre-injection and main injection are exactly connected. Use the injection interval at this time as the injection fusion reference injection interval. S2. Construct a high-speed photography direct-shot test system for the injection process of the high-pressure common rail system. Fill the constant-volume combustion bomb of the system with background gas, adjust the back pressure inside the constant-volume bomb to be consistent with the back pressure of the fuel injection law test system, and keep the test conditions consistent with the fuel injection law test. Set the injection interval as the injection fusion reference injection interval, and test the spray development characteristics under this injection interval. S3. Process images of the multiple injection spray development process of the high-pressure common rail system to confirm whether the pre-injection and main injection fuel sprays have merged at the reference injection interval. If they have not merged, continue to reduce the injection interval and repeat the spray development characteristic test until the fuel sprays of the two injections merge. The injection interval at this time is the critical injection interval for injection fusion. At this time, it is determined that the multiple injections have actually merged.

2. The test method for determining jet fusion in multiple injections of a high-pressure common rail system according to claim 1, characterized in that: In step S1, the pre-injection and main injection curves are exactly connected, meaning that the end point of the pre-injection curve coincides with the beginning point of the main injection curve.

3. The test method for determining jet fusion in multiple injections of a high-pressure common rail system according to claim 1, characterized in that: The high-pressure common rail system injection pattern test system in step S1 includes a single-shot injector. The outlet of the oil tank is connected to the inlet of the oil tank after passing through a valve, a coarse filter, a fine filter, a high-pressure oil pump, a rail pressure regulating valve, a common rail pipe, and an overflow valve. A temperature controller is also installed on the oil tank. A pressure gauge is installed on the pipeline between the fine filter and the high-pressure oil pump. A pressure gauge is installed on one end of the common rail pipe, and the other end is connected to the input end of the oil tank through an electronically controlled injector. The electronically controlled injector is located above the leakage measurement container. The ECU is connected to the pressure gauge, the rail pressure regulating valve, the pressure gauge, the common rail pipe, the electronically controlled injector, and the temperature controller to achieve overall control of the entire system.

4. The test method for determining jet fusion in multiple injections of a high-pressure common rail system according to claim 1, characterized in that: The high-speed photography direct-shot test system for the high-pressure common rail system injection process in step S2 includes an ECU and a high-pressure oil pump. The high-pressure oil pump delivers liquid from the oil tank to the electronically controlled injector via the oil rail. A constant-volume combustion bomb is located below the electronically controlled injector, and a heating device is installed inside the constant-volume combustion bomb. Quartz windows are located on opposite sides above the constant-volume combustion bomb, with a light source and a high-speed camera on the outside of the quartz windows respectively. The spray generated by the electronically controlled injector is located on the horizontal plane of the quartz windows. The high-speed camera transmits the captured images to the computer and the ECU respectively. The constant-volume combustion bomb pipeline is connected to the gas cylinder, and a pressure control valve is installed on this pipeline. The pressure control valve and the heating device are both connected to the microcontroller. The ECU is also connected to the high-pressure oil pump, the oil rail, the electronically controlled injector, and the computer respectively to complete the data acquisition and control of the entire system.

5. The test method for determining jet fusion in multiple injections of a high-pressure common rail system according to claim 1, characterized in that: In step S2, before conducting the spray visualization test, the electronically controlled fuel injector is processed by drilling a single hole with the same diameter as the original hole at the center of the nozzle tip to seal the original spray hole of the electronically controlled fuel injector.

6. The test method for determining jet fusion in multiple injections of a high-pressure common rail system according to claim 1, characterized in that: In step S2, the background gas is sulfur hexafluoride, which has a density five times that of air, and the background temperature is set to 303K. The injection interval set in the electronic control system between the end of the pre-spray and the start of the main spray is the time interval between the end of the pre-spray pulse width and the start of the main spray pulse width.

7. The test method for determining jet fusion in multiple injections of a high-pressure common rail system according to claim 1, characterized in that: In step S3, when processing the spray development process image, the presence or absence of spray fusion is determined by comparing and analyzing whether the pre-spray jet and the main spray jet in the spray development image are interrupted.

Images