Fuel injector tip heating system for generating flash boiling spray and control method

Abstract

The invention discloses a fuel injector tip heating system for generating flash boiling spray and a control method, and relates to the field of power machine spray dynamics. Comprising a heat conduction sleeve, a heating rod, a temperature sensor, a PID temperature controller, an oil sprayer and a control computer. The PID temperature controller comprises a temperature measurement module, a temperature control module, a full-isolation single-phase alternating current voltage regulation module and a case, and the temperature control module is connected with the full-isolation single-phase alternating current voltage regulation module; the heat conduction sleeve is connected with the oil injector tip of the oil injector, the heating rod and the temperature sensor, the two wiring ends of the heating rod are connected with the full-isolation single-phase alternating current voltage regulating module, and the temperature sensor is connected with the temperature measuring module. And the PID temperature controller is connected with the control computer. Through cooperative work of the heat conduction sleeve, the heating rod, the temperature sensor and the heat preservation layer, the system can rapidly increase and stably maintain the temperature of fuel oil, so that it is ensured that the fuel oil accumulated at the tip of the oil injector accurately reaches the set target temperature before injection, and finally stable flash boiling spray is formed.

Description

Technical Field

[0001] This invention relates to the field of spray dynamics in power machinery, and specifically to a fuel injector tip heating system and control method for generating flash boiling spray. Background Technology

[0002] Currently, global energy and environmental problems are becoming increasingly severe. Internal combustion engines, as widely used power devices, are a source of many environmental problems; therefore, further improving their combustion efficiency and reducing pollution emissions has become an urgent priority. Fuel atomization quality is a key factor affecting the subsequent combustion process. However, due to the complex structure and rapidly changing operating conditions of the combustion chamber in actual engine operation, it is difficult to directly observe the spray morphology and development process. Therefore, conducting research on spray characteristics under static conditions in constant-volume combustion bombs has become an important method. Among these, research on the flash boiling phenomenon is particularly crucial. When fuel is rapidly injected through the injector into a chamber where the ambient pressure is lower than its saturated vapor pressure, it instantly triggers the nucleation, growth, and collapse of bubbles inside the liquid fuel, producing a violent and explosive boiling phenomenon. This flash boiling process fully breaks up the liquid spray, producing finer droplets and accelerating fuel-air mixing, thereby significantly improving fuel atomization quality. This provides an effective way to improve the combustion efficiency of internal combustion engines and reduce pollutant emissions, and has important guiding value for the development of a new generation of efficient and clean power systems.

[0003] Currently, the control of fuel temperature within the injector is not yet perfect in the study of flash boiling spray in constant-volume combustion bombs. However, in actual engine operation, the complex thermal environment causes significant changes in fuel temperature, which directly affects its saturated vapor pressure, determining whether flash boiling occurs and its intensity, thus altering the spray pattern and atomization characteristics. Therefore, effective control of fuel temperature within the injector is of great significance for studying and controlling the flash boiling process in internal combustion engines. Summary of the Invention

[0004] To address the shortcomings of existing experimental setups in controlling fuel temperature in injectors, this invention proposes an injector tip heating system and its control method for generating flash boiling spray. This system is based on a closed-loop control architecture using a PID temperature controller, enabling precise control of the fuel temperature within the injector tip. Through the coordinated operation of a heat-conducting sleeve, heating rod, temperature sensor, and insulation layer, the fuel temperature is rapidly increased and stably maintained, ensuring that the fuel accumulated at the injector tip reaches the set target temperature before injection, ultimately forming a stable flash boiling spray.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A fuel injector tip heating system for generating flash boiling spray includes a heat-conducting sleeve, a heating rod, a temperature sensor, a PID temperature controller, a fuel injector, and a control computer. The PID temperature controller comprises a temperature measurement module, a temperature control module, a fully isolated single-phase AC voltage regulating module, and a chassis. The temperature control module, temperature measurement module, and fully isolated single-phase AC voltage regulating module are housed inside the chassis, and the temperature control module is connected to the fully isolated single-phase AC voltage regulating module. The heat-conducting sleeve is connected to the fuel injector tip, the heating rod, and the temperature sensor. The two terminals of the heating rod are connected to the fully isolated single-phase AC voltage regulating module, and the temperature sensor is connected to the temperature measurement module. The PID temperature controller is connected to the control computer. The PID temperature controller adjusts the power of the heating rod based on the feedback signal from the temperature sensor to achieve precise control of the fuel temperature.

[0006] Furthermore, the heat-conducting sleeve has a nozzle through hole along the diameter direction, and the tip of the injector is inserted through the nozzle through hole, with the inner diameter of the nozzle through hole and the outer diameter of the injector tip being tightly connected.

[0007] Furthermore, a heating rod through hole is provided on the side of the heat-conducting sleeve, and the heating rod is inserted through the heating rod through hole.

[0008] Furthermore, the heating rod has two through holes, symmetrically distributed on both sides of the fuel injector through hole, allowing two heating rods to be inserted simultaneously for uniform heating of the fuel injector tip.

[0009] Furthermore, a blind hole is provided on the side of the heat-conducting sleeve, and the temperature sensor is inserted into the blind hole. The temperature measuring node of the temperature sensor is in full contact with the heat-conducting sleeve to measure the internal temperature of the heat-conducting sleeve in real time.

[0010] Furthermore, an insulation layer is provided, which is made of ceramic fiber paper and is tightly wrapped around the outside of the heat-conducting sleeve and the heating rod.

[0011] Furthermore, the temperature measurement module is a Ni9213 temperature measurement module, and the temperature control module is a Ni9263 temperature control module.

[0012] Furthermore, the heat-conducting sleeve is made of brass; the temperature sensor is a T-type thermocouple.

[0013] A control method for an injector tip heating system for generating flash boiling spray includes the following steps: First, a target fuel temperature is set via a PID temperature controller; when a temperature sensor detects that the temperature of the heat-conducting sleeve is lower than the target fuel temperature setting, the heating rod starts working, and the PID temperature controller adjusts the heating power of the heating rod in real time according to the feedback from the temperature sensor, so that the temperature of the heat-conducting sleeve quickly reaches and stabilizes at the target fuel temperature setting; this temperature is maintained and heating continues until a pre-calibrated heating time is reached, so that the fuel accumulated at the injector tip is heated to the target fuel temperature; then fuel injection is triggered, and the fuel flashes and boils when injected into the low-pressure environment, thereby forming a flash boiling spray.

[0014] Furthermore, the pre-calibrated heating time is determined through the following process: First, the ambient pressure is increased to suppress fuel phase change, and under this condition, multiple different target fuel temperatures are set and kept constant; then, the actual temperature of the fuel injected at different heating times is measured; through this actual fuel temperature, the correspondence between the heat-conducting sleeve temperature, the heating time, and the actual fuel temperature is established, thereby determining the precise heating time required to heat the fuel from the initial room temperature to each target temperature.

[0015] The beneficial effects of this invention are: The combined design of the heat-conducting sleeve and heating rod enables efficient and uniform heating of the injector tip within a small space. The added insulation layer effectively reduces heat loss and improves the system's temperature response speed and thermal efficiency. Through the coordinated work of the heat-conducting sleeve, heating rod, temperature sensor, and insulation layer, the system can quickly raise and stably maintain the fuel temperature, thereby ensuring that the fuel accumulated at the injector tip reaches the set target fuel temperature precisely before injection, ultimately forming a stable flash boiling spray.

[0016] A closed-loop precision control system is constructed using a PID temperature controller and a temperature sensor. For the fuel heating temperature range (25-200℃) required for the flash boiling experiment, an appropriate temperature sensor is selected to ensure high-precision and stable control of the fuel temperature, meeting the strict requirements of the experiment for the target fuel temperature.

[0017] This system is compact and easy to install, enabling precise heating within a limited space. By heating the fuel at the injector tip, heat loss is effectively reduced. By adjusting the inner diameter of the heat-conducting sleeve, it can be adapted to different injector tips, offering good applicability and economy. It provides a stable and reliable temperature control solution for conducting research on flash boiling spray of different fuels. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the system of the present invention; Figure 2This is a three-dimensional schematic diagram of the fuel injector in this invention; Figure 3 This is a schematic diagram showing the connection between the heat-conducting sleeve and the injector tip, heating rod, and temperature sensor in this invention. Figure 4 This is a two-dimensional front view of the heat-conducting sleeve in this invention; Figure 5 This is a two-dimensional side view of the heat-conducting sleeve in this invention; Figure 6 This is a two-dimensional top view of the heat-conducting sleeve in this invention; Figure 7 This is a schematic diagram of the control panel for controlling the computer in this invention.

[0019] The components are: 1. Heat-conducting sleeve, 2. Heating rod, 3. Temperature sensor, 4. Temperature measurement module, 5. Injector tip, 6. Injector, 7. Fully isolated single-phase AC voltage regulating module, 8. Heating rod through hole, 9. Blind hole, 10. Injector nozzle through hole, 11. Temperature control module, 12. Chassis, 13. Control computer. Detailed Implementation

[0020] The following is in conjunction with the appendix Figure 1 —7 The technical solutions of the present invention have been clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The present invention is described in detail below through specific embodiments, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained commercially.

[0022] In the description of this invention, it should be noted that the terms "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] Example 1 The injector tip heating system for generating flash boiling spray includes a heat-conducting sleeve 1, a heating rod 2, a temperature sensor 3, a PID temperature controller, an injector 6, and a control computer 13. The PID temperature controller includes a temperature measuring module 4, a temperature control module 11, a fully isolated single-phase AC voltage regulating module 7, and a chassis 12. The temperature control module 11, temperature measuring module 4, and fully isolated single-phase AC voltage regulating module 7 are housed inside the chassis 12, and the temperature control module 11 is connected to the fully isolated single-phase AC voltage regulating module 7. The heat-conducting sleeve 1 is connected to the injector tip 5, heating rod 2, and temperature sensor 3 of the injector 6. The two terminals of the heating rod 2 are connected to the fully isolated single-phase AC voltage regulating module 7, and the temperature sensor 3 is connected to the temperature measuring module 4. The PID temperature controller is connected to the control computer 13. The PID temperature controller adjusts the power of the heating rod based on the feedback signal from the temperature sensor 3 to achieve precise control of the fuel temperature.

[0025] The heat-conducting sleeve 1 has a fuel injector through hole 10 along the diameter direction. The outer diameter of the heat-conducting sleeve 1 is φ22mm and the height is 17mm. The diameter of the fuel injector through hole 10 is φ7.15mm. The outer diameter of the fuel injector tip is φ7mm. The fuel injector tip 5 is inserted through the fuel injector through hole 10 and the fuel injector through hole 10 and the fuel injector tip 5 are tightly connected.

[0026] The heat-conducting sleeve 1 has a heating rod through-hole 8 on its side, and the heating rod 2 is inserted through the heating rod through-hole 8. There are two heating rod through-holes 8, symmetrically distributed on both sides of the injector through-hole 10, allowing two heating rods 2 to be inserted simultaneously, so that the injector tip 5 is uniformly heated. The diameter of the heating rod through-hole 8 is φ6.1mm, the heating rod 2 is made of stainless steel, with specifications of φ6mm×30mm, working voltage of 220V, and a single rod power of approximately 80W. The heating rod 2 fits tightly with the heating rod through-hole 8.

[0027] The heat-conducting sleeve 1 also has a blind hole 9 on its side. The temperature sensor 3 is inserted into the blind hole 9. The temperature measuring node of the temperature sensor 3 is in full contact with the heat-conducting sleeve 1 to measure the internal temperature of the heat-conducting sleeve 1 in real time and feed it back to the PID temperature controller.

[0028] An insulation layer is also provided, which is made of ceramic fiber paper. It is tightly wrapped around the outside of the heat-conducting sleeve 1 and the heating rod 2 and fixed with stainless steel cable ties, which effectively reduces heat loss and improves temperature response speed.

[0029] The temperature measuring module 4 is a Ni9213 temperature measuring module, and the temperature control module 11 is a Ni9263 temperature control module.

[0030] The heat-conducting sleeve 1 is made of brass, which has a fast heat conduction speed and a fast heating speed. The temperature sensor 3 is a T-type thermocouple with a probe diameter of φ1.5mm, which is inserted into the blind hole 9 of the heat-conducting sleeve to ensure that the temperature measuring node is in full contact with the heat-conducting sleeve and to ensure high-precision temperature control.

[0031] The PID temperature controller has both manual setting and automatic adjustment functions. It can set the target fuel temperature according to experimental requirements and stabilize the target fuel temperature within the range of 25℃ to 200℃ through closed-loop control.

[0032] The PID temperature controller and the control computer 13 work together to achieve closed-loop control of the target fuel temperature. Specifically, the temperature sensor 3 is connected to the temperature measurement module 4 to collect the temperature of the heat-conducting sleeve 1 in real time; the heating rod 2 is connected to the fully isolated single-phase AC voltage regulating module 7, which receives the control signal output by the temperature control module 11 to adjust the voltage, thereby controlling the heating power of the heating rod 2; the PID temperature controller is connected to the control computer 13 through a communication interface to transmit temperature data in real time and receive the set temperature command from the computer; the temperature control module 11 outputs a control signal based on the measured temperature data and the set target fuel temperature.

[0033] A control method for an injector tip heating system for generating flash boiling spray includes the following steps: First, a target fuel temperature is set via a PID temperature controller; when the temperature sensor 3 detects that the temperature of the heat-conducting sleeve 1 is lower than the target fuel temperature setting, the heating rod 2 starts working, and the PID temperature controller adjusts the heating power of the heating rod 2 in real time according to the feedback from the temperature sensor 3, so that the temperature of the heat-conducting sleeve 1 quickly reaches and stabilizes at the target fuel temperature setting; this temperature is maintained and heating continues until a pre-calibrated heating time is reached, so that the fuel accumulated at the injector tip is heated to the target fuel temperature; then fuel injection is triggered, and the fuel flashes and boils when injected into the low-pressure environment, thereby forming a flash boiling spray.

[0034] Because directly measuring the internal fuel temperature of the injector 6 is difficult, this system actually measures the temperature of the heat-conducting sleeve 1. When the heating time is insufficient, this temperature differs from the actual fuel temperature inside the injector. Therefore, the system needs to pre-calibrate the heating time before operation: first, ambient pressure is increased to suppress fuel phase change, and under this condition, multiple different target fuel temperatures are set and kept constant; then, the actual temperature of the injected fuel is measured at different heating durations. Using this actual fuel temperature, a correspondence is established between the heat-conducting sleeve temperature, heating time, and actual fuel temperature, thereby determining the precise time required to heat the fuel from its initial room temperature to each target temperature. Finally, by controlling this heating time, precise control of the fuel temperature inside the injector can be achieved.

[0035] The heat transfer path of this invention mainly utilizes a dual-mechanism synergy: On one hand, the heat generated by the heating rod 2 rapidly heats the heat-conducting sleeve 1, which is then efficiently transferred to the outer wall of the injector tip 5 via solid-state heat conduction, and subsequently heats the fuel inside through its inner wall; on the other hand, the inner wall of the injector tip 5 directly contacts the needle valve inside the injector 6, causing the needle valve temperature to rise rapidly as well, thereby heating the fuel within the fuel passage. This synergistic effect of the dual heating mechanisms significantly improves the efficiency and uniformity of fuel heating within the injector, enhancing the stability and accuracy of the system's fuel temperature control.

[0036] The embodiments described above are merely preferred embodiments of the present invention, and not all feasible embodiments of the present invention. For those skilled in the art, any obvious modifications made without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims. Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no technical conflict, the features in the embodiments disclosed in the present invention can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A fuel injector tip heating system for generating flash boiling spray, characterized in that, The system includes a heat-conducting sleeve (1), a heating rod (2), a temperature sensor (3), a PID temperature controller, an injector (6), and a control computer (13). The PID temperature controller includes a temperature measuring module (4), a temperature control module (11), a fully isolated single-phase AC voltage regulating module (7), and a chassis (12). The temperature control module (11), the temperature measuring module (4), and the fully isolated single-phase AC voltage regulating module (7) are placed inside the chassis (12). The temperature control module (11) is connected to the fully isolated single-phase AC voltage regulating module (7). The heat-conducting sleeve (1) is connected to the injector tip (5), the heating rod (2), and the temperature sensor (3) of the injector (6). The two terminals of the heating rod (2) are connected to the fully isolated single-phase AC voltage regulating module (7), and the temperature sensor (3) is connected to the temperature measuring module (4). The PID temperature controller is connected to the control computer (13).

2. The injector tip heating system for generating flash boiling spray according to claim 1, characterized in that, The heat-conducting sleeve (1) has an injector through hole (10) along the diameter direction. The injector tip (5) is inserted through the injector through hole (10). The inner diameter of the injector through hole (10) is tightly connected to the outer diameter of the injector tip (5).

3. The injector tip heating system for generating flash boiling spray according to claim 1, characterized in that, The heat-conducting sleeve (1) has a heating rod through hole (8) on its side, and the heating rod (2) is inserted through the heating rod through hole (8).

4. The injector tip heating system for generating flash boiling spray according to claim 3, characterized in that, The number of heating rod through holes (8) is 2, symmetrically distributed on both sides of the fuel injector through hole (10), and two heating rods (2) can be inserted at the same time to uniformly heat the fuel injector tip (5).

5. The injector tip heating system for generating flash boiling spray according to claim 1, characterized in that, The heat-conducting sleeve (1) also has a blind hole (9) on its side. The temperature sensor (3) is inserted into the blind hole (9). The temperature measuring node of the temperature sensor (3) is in full contact with the heat-conducting sleeve (1) for real-time measurement of the internal temperature of the heat-conducting sleeve (1).

6. The injector tip heating system for generating flash boiling spray according to claim 1, characterized in that, It is also provided with a heat insulation layer, which is made of ceramic fiber paper and is tightly wrapped around the outside of the heat-conducting sleeve (1) and the heating rod (2).

7. The injector tip heating system for generating flash boiling spray according to claim 1, characterized in that, The temperature measurement module (4) is a Ni9213 temperature measurement module, and the temperature control module (11) is a Ni9263 temperature control module.

8. The injector tip heating system for generating flash boiling spray according to claim 1, characterized in that, The heat-conducting sleeve (1) is made of brass; the temperature sensor (3) is a T-type thermocouple.

9. The control method for an injector tip heating system for generating flash boiling spray according to any one of claims 1-8, characterized in that, Includes the following steps: First, the target fuel temperature is set by the PID temperature controller. When the temperature sensor (3) detects that the temperature of the heat-conducting sleeve (1) is lower than the target fuel temperature setting value, the heating rod (2) starts to work. The PID temperature controller adjusts the heating power of the heating rod (2) in real time according to the feedback of the temperature sensor (3), so that the temperature of the heat-conducting sleeve (1) quickly reaches and stabilizes at the target fuel temperature setting value. The temperature is maintained and heated for a pre-calibrated heating time, so that the fuel accumulated at the tip (5) of the injector is heated to the target fuel temperature. Then, the fuel injection is triggered, and the fuel undergoes flash boiling when injected into the low-pressure environment, thereby forming a flash boiling spray.

10. The control method according to claim 9, characterized in that, The pre-calibrated heating time is determined through the following process: First, the ambient pressure is increased to suppress fuel phase change, and under this condition, multiple different target fuel temperatures are set and kept constant; then, the actual temperature of the fuel injected at different heating times is measured; based on this actual fuel temperature, the correspondence between the heat-conducting sleeve temperature, the heating time, and the actual fuel temperature is established, thereby determining the precise heating time required to heat the fuel from the initial room temperature to each target temperature.

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