Biodiesel engine spray image acquisition device and analysis method

Abstract

The invention provides a biodiesel engine spray image acquisition device and an analysis method. The biodiesel engine spray image acquisition device comprises a fuel injection structure, a constant volume combustion bomb and an image acquisition module, the fuel injection structure is used for injecting diesel oil into the constant-volume combustion bomb; a first glass window and a second glass window which are opposite to each other are arranged on the surface of the constant-volume combustion bomb; the parallel light vertically passes through the first glass window, is projected into the constant volume combustion bomb, then is emitted through the second glass window, and is sent to the image acquisition and analysis module after being focused; and the image acquisition module is used for shooting focused light images through a high-speed digital camera. The test device is simple in design, reliable in performance, simple to use and maintain, capable of measuring the spraying performance of the biodiesel engine under the condition of adjustable oil injection rate, and suitable for popularization and application.

Description

Technical Field

[0001] The invention relates to the technical field of biodiesel engine performance testing, and in particular to a spray image acquisition device and an analysis method for a biodiesel engine. Background Art

[0002] High-pressure common rail electronic fuel injection technology for diesel engines is one of the iconic technologies of modern advanced diesel engines. The development of combustion theory has put forward higher requirements for injection rate to achieve more flexible injection control under different working conditions of diesel engines.

[0003] Changes in the injection rate will cause changes in the oil-gas mixing process in the cylinder, which will in turn affect the spray performance of the biodiesel engine, and ultimately affect the overall performance of the biodiesel engine. However, there is currently no complete test device for accurately measuring the spray performance of the biodiesel engine under the condition of adjustable injection rate. In the measurement of the spray performance of the biodiesel engine, the acquisition of the spray image is extremely important, which to a certain extent affects the overall improvement of the performance of the biodiesel engine under the full range of working conditions. Therefore, a device for accurately acquiring the spray image of the biodiesel engine is urgently needed. Summary of the invention

[0004] The invention proposes a biodiesel engine spray image acquisition device and analysis method to solve the technical problem that the spray performance of a biodiesel engine with adjustable fuel injection rate is difficult to accurately measure.

[0005] In order to solve the above technical problems, the present invention provides a device for measuring the spray performance of a biodiesel engine with adjustable fuel injection rate, comprising a fuel injection structure, a constant volume combustion bomb, an image acquisition module and an analysis module;

[0006] The fuel injection structure is used to inject diesel into the constant volume combustion bomb;

[0007] The surface of the constant volume combustion bomb is arranged with a first glass window and a second glass window facing each other;

[0008] The parallel light is vertically projected into the constant volume combustion bomb through the first glass window, then emitted through the second glass window, and sent to the image acquisition module after being focused;

[0009] The image acquisition module captures the focused light image through a high-speed digital camera.

[0010] Preferably, the fuel injection structure includes a high-pressure fuel pump, a common rail pipe, a booster device and a fuel injector;

[0011] The high-pressure oil pump is connected to the input end of the common rail pipe and is used to provide biodiesel to the common rail pipe;

[0012] The boosting device is connected to the output end of the common rail pipe, and the biodiesel is allowed to enter the injector through the boosting effect;

[0013] The injector is used to inject the pressurized biodiesel into the constant volume combustion bomb;

[0014] The fuel injector is sealed and connected to the constant volume combustion bomb.

[0015] Preferably, the boost device and the fuel injector are controlled by the boost device solenoid valve and the fuel injector solenoid valve respectively; and the injection rate is adjusted by adjusting the control signal timing of the boost device solenoid valve and the fuel injector solenoid valve.

[0016] Preferably, the injector is fixed by a rotatable clamp.

[0017] Preferably, a stop valve is provided at the bottom of the constant volume combustion bomb.

[0018] Preferably, a pressure sensor and / or a temperature sensor is provided in the constant volume combustion bomb.

[0019] Preferably, an electric heater is provided in the constant volume combustion bomb.

[0020] Preferably, the constant volume combustion bomb is provided with a two-way airtight valve for injecting and exhausting nitrogen.

[0021] Preferably, the resolution of the high-speed digital camera is 600×300, the shooting rate is 15000 frames / s, the interval time between each frame is 60 μs, and the exposure time is 15 μs.

[0022] The present invention also provides a biodiesel engine spray image analysis method, which is implemented based on the spray image collected by the above-mentioned biodiesel engine spray image collection device. First, the spray image (RGB) is converted into a grayscale image; then a histogram is drawn; finally, the grayscale image is converted into a binary image. When the brightness of the binary image is lower than a set threshold pixel point, the output is 0, and when the brightness is higher than the set threshold pixel point, the output is 1, and a spray image with only a spray boundary line is obtained, thereby obtaining the spray image information.

[0023] The beneficial effects of the present invention include at least:

[0024] The biodiesel engine spray performance measuring device of the present invention has a simple design, reliable performance, and simple use and maintenance, and can measure the spray performance of the biodiesel engine under the condition of adjustable injection rate, and is suitable for popularization and application, laying a foundation for further improving the overall performance of the biodiesel engine within the full range of working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1It is a structural schematic diagram of an embodiment of the present invention;

[0026] Figure 2 It is a schematic diagram showing the effect of the injection rate curve shape on the spray oil beam morphology of a biodiesel engine according to an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of the control system structure of an embodiment of the present invention;

[0028] Figure 4 Schematic diagram of the image analysis process according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0030] like Figure 1 As shown, an embodiment of the present invention provides a biodiesel engine spray image acquisition device, including a fuel injection structure, a constant volume combustion bomb, an image acquisition module and an analysis module.

[0031] The fuel injection structure is used to spray diesel into the constant volume combustion bomb.

[0032] A first glass window and a second glass window that are opposite to each other are arranged on the surface of the constant volume combustion bomb.

[0033] The parallel light emitted by the light source is vertically projected into the constant volume combustion bomb through the first glass window, then emitted through the second glass window, and sent to the image acquisition module after being focused.

[0034] The image acquisition module captures the focused light image through a high-speed digital camera.

[0035] When the biodiesel engine spray image acquisition device of the present invention is in use, the fuel injection structure will inject diesel into the constant volume combustion bomb through the injector. Due to the entry of the injection fuel, the density gradient of the spray field in the constant volume combustion bomb will change.

[0036] The parallel light emitted by the light source passes vertically through the first glass window and is projected into the constant volume combustion bomb. After the parallel light enters the constant volume combustion bomb, it is refracted due to the density gradient change caused by the spray field. After refraction, it is emitted through the second glass window opposite to the first glass window, and is received by the high-speed digital camera after focusing, thereby obtaining the spray image of the biodiesel engine.

[0037] In this embodiment, the light source forms parallel light through a spherical mirror, and the light emitted by the light source is converted into parallel light that enters the first glass window through the spherical mirror. At the same time, the light emitted from the second glass window is focused through the spherical mirror, wherein the diameter of the spherical mirror is 160 mm.

[0038] The high-speed digital camera in the image acquisition module can be used to capture spray images for analyzing processes such as fuel injection, atomization and evaporation. The resolution of the high-speed digital camera is 600×300, the shooting rate is 15,000 frames / s, the interval between each frame is 60μs, the exposure time is 15μs, and the shooting signal is triggered by the rising edge of the TTL level of the injection signal.

[0039] In this embodiment, the spray images under different conditions are collected by changing the injection rate of the fuel injection structure. The collected images are as follows: Figure 2 As shown, from Figure 2 It can be seen that under different injection rate curves, clear imaging structures with clear features can be obtained, which lays the foundation for the subsequent analysis of biodiesel engine spray performance.

[0040] from Figure 2 It can be seen that the fragmentation and evaporation phenomenon around the oil beam in the rectangular injection rate curve is the most obvious, followed by the ramp injection rate curve, and finally the boot-shaped injection rate curve. This is because the boost moment of the rectangular injection rate curve is earlier than the injection moment, and a higher injection pressure is reached at the beginning and maintained until the end of injection. The higher the injection pressure, the easier it is for the fuel to evaporate and the better the atomization effect, that is, the easier it is for the fuel and air to contact in the cylinder, and the more uniform the oil-gas mixture formed, so the fragmentation and evaporation phenomenon around the oil beam in the rectangular injection rate curve is the most obvious.

[0041] Specifically, in this embodiment, the fuel injection structure is an ultra-high pressure common rail system, which is mainly composed of a high pressure oil pump, a common rail pipe, a supercharging device and a fuel injector, wherein the high pressure oil pump provides biodiesel to the common rail pipe, and then the biodiesel is ejected through the fuel injector based on the supercharging effect of the supercharging device. For example, during the test, the fuel injector is fixed with a fixture to ensure that it has the same installation angle as the biodiesel engine.

[0042] In this embodiment, in order to achieve more flexible adjustment of the injection rate, the supercharging device and the injector are controlled by their own solenoid valves. By adjusting the control signal timing of the supercharging device solenoid valve and the injector solenoid valve, the injection rate can be flexibly adjusted. In this way, by setting a dual-control electronic control unit, the supercharging device solenoid valve and the injector solenoid valve are controlled separately, and the injection amount and the boost pressure can be dynamically adjusted according to the real-time changes in the engine working conditions, so as to achieve precise coordination between injection and boost.

[0043] Specifically, the constant volume combustion bomb in the present embodiment is an important device of the biodiesel engine spray performance test device. In order to further adjust its internal back pressure and discharge excess oil-gas mixture in the present embodiment, a stop valve is installed at the bottom of the constant volume combustion bomb. In addition, the constant volume combustion bomb is also equipped with a small hole for installing a sensor, so that a pressure sensor and / or a temperature sensor can be installed to measure parameters such as pressure and temperature. During the test, an electric heating method is used to simulate the cylinder wall temperature, and the cylinder density at the top dead center of the diesel engine is simulated by filling with nitrogen, and nitrogen is injected and removed through the two-way airtight valve provided on the constant volume combustion bomb. It should be noted that in order to obtain a high temperature and high pressure state, all structures opened or connected on the constant volume combustion bomb in the present embodiment adopt a sealed connection method to ensure the sealing of the constant volume combustion bomb.

[0044] In this embodiment, in order to further control the boost device solenoid valve and the injector solenoid valve, the following control system is also provided.

[0045] The control system includes computers, electronic control units, etc. The control program is written through Labview. Its function is to provide driving current for the solenoid valve of the boost device and the solenoid valve of the injector to ensure the synchronization between the crankshaft and camshaft position signals, boost control signals, injection control signals and shooting signals. It is mainly composed of hardware and software.

[0046] The hardware structure is shown in the figure Figure 3 As shown, it mainly includes five modules: microcontroller, processing, drive, power supply and communication.

[0047] The software part is constructed according to the requirements of the spray performance test measurement, including serial communication program, control pulse program and external interrupt program, etc. This embodiment writes a microcontroller program based on the keil-C environment, which can process the collected crankshaft and camshaft signals, control the action of the solenoid valve, and then control the boost parameters and injection parameters. At the same time, in order to realize real-time monitoring of the test parameters, the upper computer program is designed using LabVIEW software, and the corresponding spray performance test control system software is developed. During the test, the boost parameters and injection parameters can be adjusted on the control interface, and the values ​​of the parameters in the lower computer program can be changed synchronously through serial communication.

[0048] Example 2

[0049] The present invention also provides a biodiesel engine spray image analysis method, which is implemented based on the spray image collected by the above-mentioned biodiesel engine spray image collection device.

[0050] Specifically, Figure 4As shown in Figure 2, the spray image is processed using Matlab software. First, the image (RGB) is converted into a grayscale image, as shown in Figure 2. Figure 4 (a) in ; then use the imhist command to draw a histogram, such as Figure 4 (b) in the figure; finally, the grayscale image is converted into a binary image based on the IM2BW function. When the brightness of the binary image is lower than the set threshold pixel point, the output is 0, and when the brightness is higher than the set threshold pixel point, the output is 1. After the above processing, only the spray boundary line remains in the image, as shown in Figure 4 By looking at (c) in the figure, you can get information such as spray penetration distance and spray cone angle.

[0051] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. Only the preferred embodiments of the present invention are expressed. The description is more specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. As long as there is no contradiction in the combination of these technical features, they should be considered as the scope recorded in this specification.

[0052] It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A biodiesel engine spray image acquisition device, characterized in that: It includes a fuel injection structure, a constant volume combustion bomb, an image acquisition module and an analysis module; The fuel injection structure is used to inject diesel into the constant volume combustion bomb; The surface of the constant volume combustion bomb is provided with a first glass window and a second glass window facing each other; The parallel light is vertically projected into the constant volume combustion bomb through the first glass window, then emitted through the second glass window, and is sent to the image acquisition and analysis module after being focused; The image acquisition module captures the focused light image through a high-speed digital camera.

2. The spray image acquisition device for a biodiesel engine according to claim 1, characterized in that: The fuel injection structure includes a high-pressure oil pump, a common rail pipe, a supercharging device and a fuel injector; The high-pressure oil pump is connected to the input end of the common rail pipe and is used to provide biodiesel to the common rail pipe; The boosting device is connected to the output end of the common rail pipe, and the biodiesel is allowed to enter the injector through the boosting effect; The injector is used to inject the pressurized biodiesel into the constant volume combustion bomb; The fuel injector is sealed and connected to the constant volume combustion bomb.

3. A biodiesel engine spray image acquisition device according to claim 2, characterized in that: The booster device and the fuel injector are controlled by the booster device solenoid valve and the fuel injector solenoid valve respectively; the fuel injection rate is adjusted by adjusting the control signal timing of the booster device solenoid valve and the fuel injector solenoid valve.

4. A biodiesel engine spray image acquisition device according to any one of claims 2 or 3, characterized in that: The fuel injector is fixed by a rotatable clamp.

5. The biodiesel engine spray image acquisition device according to claim 1, characterized in that: A stop valve is arranged at the bottom of the constant volume combustion bomb.

6. The biodiesel engine spray image acquisition device according to claim 1, characterized in that: The constant volume combustion bomb is provided with a pressure sensor and / or a temperature sensor.

7. The biodiesel engine spray image acquisition device according to claim 1, characterized in that: An electric heater is arranged in the constant volume combustion bomb.

8. The biodiesel engine spray image acquisition device according to claim 1, characterized in that: The constant volume combustion bomb is provided with a two-way airtight valve for injecting and exhausting nitrogen.

9. The biodiesel engine spray image acquisition device according to claim 1, characterized in that: The resolution of the high-speed digital camera is 600×300, the shooting rate is 15000 frames / s, the interval between each frame is 60μs, and the exposure time is 15μs.

10. A method for analyzing a spray image of a biodiesel engine, implemented based on a spray image acquired by a biodiesel engine spray image acquisition device according to any one of claims 1 to 9, characterized in that: First, the spray image (RGB) is transformed into a grayscale image; then a histogram is drawn; finally, the grayscale image is converted into a binary image. When the brightness of the binary image is lower than the set threshold pixel point, the output is 0, and when the brightness is higher than the set threshold pixel point, the output is 1, and a spray image with only the spray boundary line is obtained, and the spray image information can be obtained.

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