Diesel engine oil supply condition control system and control method

Abstract

The application provides a diesel engine oil supply condition control system and control method, comprising: an oil tank oil inlet oil path and a diesel engine oil return oil path are connected in parallel before a fuel frequency conversion pump, and the diesel engine oil return oil path is connected to the diesel engine oil inlet oil path through the fuel frequency conversion pump; the fuel frequency conversion pump converges and pressurizes the oil tank fuel and the diesel engine oil return; the cooling water circulation flow path is communicated with the diesel engine oil return oil path, the diesel engine oil inlet oil path and the fuel frequency conversion pump respectively; the diesel engine oil inlet oil path is provided with a diesel engine oil inlet three-way valve; the diesel engine oil inlet three-way valve is controlled by a PID control algorithm to control the diesel engine fuel oil supply temperature; the diesel engine oil inlet oil path is further provided with a pressure reducing valve; the pressure reducing valve position is adjusted by the PID control algorithm to further adjust the diesel engine fuel oil supply pressure. The application can realize accurate and stable control of the diesel engine fuel oil supply temperature and supply pressure, realize stable diesel engine fuel oil supply pressure in all working conditions of the diesel engine bench test, and meet the diesel engine bench test oil supply requirements.

Description

Technical Field

[0001] This application belongs to the field of diesel engine testing, and in particular relates to a diesel engine fuel supply condition control system and control method. Background Technology

[0002] The volume of fuel injected into a diesel engine is one of the main factors directly affecting the performance parameters of the engine. The volume of fuel injected is determined by the injection pressure, injection temperature, and injection duration. Since the injection duration is a control variable in the engine calibration, once the engine calibration is completed, the injection duration for each operating condition is determined. However, the density of fuel decreases as the fuel temperature rises and increases slightly as the fuel pressure increases. With the fuel injection duration remaining constant, the change in fuel density will inevitably cause a change in the injection volume, which in turn will cause a change in the engine's performance parameters. To meet the consistency requirements for measuring the performance parameters of diesel engine bench tests, the full-condition bench tests of diesel engines require the laboratory to supply fuel with stable temperature and pressure control.

[0003] Chinese patent "A System for Measurement and Control of Diesel Consumption in the Laboratory", publication number CN103487101A, aims to provide a system for measuring and controlling diesel consumption in the laboratory, which can meet the requirements of controlling diesel inlet temperature and pressure in engine testing, while also measuring diesel consumption under different operating conditions of the diesel engine. However, the patented invention has the following drawbacks: ① The diesel engine's return oil venting is achieved by switching the oil flow direction using a reversing valve. The reversing condition is whether there is gas in the return oil. This system lacks a sensor to detect whether there is gas in the diesel engine's return oil, requiring manual judgment. This method releases diesel and gas simultaneously during venting, and it is installed after the fuel consumption meter. Once the return oil is vented, the fuel consumption meter measures diesel including the vented portion, affecting the fuel supply; ② When the diesel engine is not working, i.e., there is no fuel consumption, the low-pressure oil circuit has no cooling self-circulation, causing the fuel temperature after the pump to rise continuously. If this state is operated for a long time, it may damage the pump or even cause a safety accident; ③ The diesel consumption measurement error is large. The fuel does not eliminate air bubbles after being pressurized by two stages of pumps, affecting the actual fuel consumption volume of the diesel engine; ④ The return oil temperature is not controlled. When the return oil temperature is too high, it is easy to exceed the temperature regulation range in summer; ⑤ When the diesel engine's return oil pressure is high, the reversing valve is not switched in time, resulting in high return oil pressure and the risk of backflow from the fuel consumption meter.

[0004] Chinese patent CN104316326A, entitled "A Diesel Engine Laboratory Fuel Assist System," provides a diesel engine laboratory fuel assist system capable of precisely controlling the diesel engine's inlet temperature and inlet / return pressure, as well as accurately measuring fuel consumption, under different engine models, operating conditions, and testing requirements, thereby ensuring the authenticity, stability, and accuracy of test data. However, from the patent's perspective, the control of diesel inlet temperature and pressure is related to the control of return pressure via an "OR" relationship, which is not clearly demonstrated in the patent's design. Furthermore, analysis of the patent's design reveals the following issues: ① Large diesel consumption measurement error: The lack of a venting function after the diesel engine's inlet pump affects the actual volumetric fuel consumption of the diesel engine, and the large fluctuations in volumetric fuel consumption measurements caused by the diesel engine's return venting. ② Large fluctuations in inlet pressure: The frequency of the variable frequency pump is adjusted via an inlet pressure sensor. ③ Neither of the two variable frequency pumps in the system incorporates an overpressure self-circulation cooling function.

[0005] In summary, diesel engine bench testing places high demands on the temperature and pressure of the fuel supply in the test chamber. The fuel supply pressure and temperature in the test chamber need to be precisely and stably controlled to meet the consistency requirements of the performance parameters of diesel engine bench testing. However, the published invention patent solutions cannot meet the current needs of diesel engine bench testing. Summary of the Invention

[0006] In view of this, this application aims to propose a diesel engine fuel supply condition control system and control method to solve the problems of inaccurate fuel inlet temperature control, unstable fuel inlet pressure control, and high failure rate of diesel engine fuel supply system.

[0007] To achieve the above objectives, the technical solution of this application is implemented as follows:

[0008] In a first aspect, this application provides a diesel engine fuel supply condition control system, including an oil depot inlet line, a diesel engine return line, a diesel engine inlet line, a cooling water circulation path, and a fuel variable frequency pump;

[0009] The oil depot's inlet oil line and the diesel engine's return oil line are connected in parallel to the fuel variable frequency pump, and then connected to the diesel engine's inlet oil line via the fuel variable frequency pump. The fuel variable frequency pump combines the pressurized oil depot fuel and the diesel engine's return oil, and then goes to the diesel engine end via the diesel engine's inlet oil line.

[0010] The cooling water circulation path is connected to the diesel engine return oil path, the diesel engine inlet oil path and the fuel variable frequency pump respectively. The diesel engine inlet oil path is equipped with a diesel engine inlet three-way valve. The diesel engine inlet three-way valve is controlled by the PID control algorithm to adjust the ratio of cooled fuel and heated fuel, thereby controlling the diesel engine fuel supply temperature.

[0011] The diesel engine fuel inlet circuit is also equipped with a pressure reducing valve connected to the diesel engine fuel inlet three-way valve. The valve position of the pressure reducing valve is adjusted by a PID control algorithm to regulate the diesel engine fuel supply pressure.

[0012] Secondly, based on the same inventive concept, this application also provides a method for controlling the fuel supply conditions of a diesel engine, the control method comprising:

[0013] In response to controlling the diesel engine inlet fuel temperature, the diesel engine return fuel and the fuel tank inlet fuel are combined at the fuel variable frequency pump. The combined fuel is pressurized by the fuel variable frequency pump and divided into two paths. One path of fuel passes through a second cooling heat exchanger cooled by cooling water, and the other path of fuel passes through a heating heat exchanger heated by hot water. Both paths flow through the diesel engine inlet three-way valve. The PID control algorithm adjusts the valve position of the diesel engine inlet three-way valve to control the mixing ratio of cooling fuel and heating fuel, thereby controlling the diesel engine fuel supply temperature.

[0014] Compared with the prior art, the diesel engine fuel supply condition control system and control method of this application have the following advantages:

[0015] This application discloses a diesel engine fuel supply condition control system and control method. A designed diesel engine test bench is used for diesel engine fuel testing. Through interconnected fuel depot inlet circuit, diesel engine return circuit, diesel engine inlet circuit, cooling water circulation circuit, and fuel frequency converter pump, a PID control algorithm is used to achieve precise and stable control of the diesel engine fuel supply temperature and pressure. This ensures stable fuel supply pressure under all operating conditions, meets the fuel supply requirements of the diesel engine test bench, and guarantees the authenticity, stability, and accuracy of the test data. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0017] Figure 1 This is a schematic diagram of a diesel engine fuel supply condition control system according to an embodiment of this application;

[0018] Figure 2 This is an electrical schematic diagram of a diesel engine fuel supply condition control system according to an embodiment of this application;

[0019] Figure 3 This is a schematic diagram of the diesel engine oil inlet flow direction and temperature control according to an embodiment of this application;

[0020] Figure 4 This is a schematic diagram of the diesel engine oil inlet flow direction and pressure control according to an embodiment of this application. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0022] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0023] As described in the background section, the relevant diesel engine fuel supply control system and control method have the following technical defects, making it difficult to meet the requirements of diesel engine bench testing.

[0024] 1) During the diesel engine test, the inlet pressure decreased as the diesel engine load increased and increased as the diesel engine load decreased, making it impossible to achieve stable inlet pressure under all operating conditions;

[0025] 2) In winter, the fuel temperature control device has insufficient heating capacity. Even with the cooler fully off and the heater fully on, the diesel engine's oil inlet temperature is still lower than the set value.

[0026] 3) In summer, the fuel temperature control device has insufficient cooling capacity. Even with the cooler fully open and the heater fully closed, the diesel engine inlet oil temperature is still higher than the set value.

[0027] 4) The diesel engine return oil pressure is adjustable, but there is no protection when the diesel return oil volume suddenly increases, which may damage the equipment.

[0028] 5) When the diesel return oil temperature is too high, there is no diesel return oil cooling function, which causes the diesel engine oil inlet temperature to rise and exceed the temperature regulation range of the fuel temperature control device.

[0029] 6) The oil supply system has a high failure rate, mainly manifested in problems such as inability to control the oil inlet temperature and pressure.

[0030] Based on this, one or more embodiments of this application provide a diesel engine fuel supply condition control system and control method.

[0031] The embodiments of this application are described in detail below with reference to the accompanying drawings.

[0032] Please see Figure 1 As shown, this embodiment provides a diesel engine fuel supply condition control system, including an oil depot inlet line, a diesel engine return line, a diesel engine inlet line, a cooling water circulation path, and a fuel variable frequency pump;

[0033] The oil depot's inlet oil line and the diesel engine's return oil line are connected in parallel to the fuel variable frequency pump, and then connected to the diesel engine's inlet oil line via the fuel variable frequency pump. The fuel variable frequency pump combines the pressurized oil depot fuel and the diesel engine's return oil, and then goes to the diesel engine end via the diesel engine's inlet oil line.

[0034] The cooling water circulation path is connected to the diesel engine return oil path, the diesel engine inlet oil path and the fuel variable frequency pump respectively. The diesel engine inlet oil path is equipped with a diesel engine inlet three-way valve. The diesel engine inlet three-way valve is controlled by the PID control algorithm to adjust the ratio of cooled fuel and heated fuel, thereby controlling the diesel engine fuel supply temperature.

[0035] The diesel engine fuel inlet circuit is also equipped with a pressure reducing valve connected to the diesel engine fuel inlet three-way valve. The valve position of the pressure reducing valve is adjusted by a PID control algorithm to regulate the diesel engine fuel supply pressure.

[0036] Specifically, in this embodiment, a diesel engine fuel supply condition test is conducted using a designed diesel engine test bench. Through the interconnected fuel depot inlet line, diesel engine return line, diesel engine inlet line, cooling water circulation path, and fuel variable frequency pump, a PID control algorithm is used to achieve precise and stable control of the diesel engine fuel supply temperature and pressure, thereby achieving stable fuel supply pressure under all operating conditions, meeting the fuel supply requirements of the diesel engine test bench, and ensuring the authenticity, stability, and accuracy of the test data.

[0037] Furthermore, the diesel engine fuel supply condition control system described in this embodiment can meet the requirements of different engine models under different operating conditions and different tests. It can accurately control the diesel engine's inlet temperature, inlet pressure, and return pressure, as well as accurately measure fuel consumption, thereby ensuring the authenticity, stability, and accuracy of test data. This solves the problems of inaccurate control of diesel engine inlet temperature, unstable control of inlet pressure, and high failure rate of diesel engine fuel supply systems.

[0038] It should be noted that the diesel engine described in this embodiment is applicable to full-condition bench testing of diesel engines such as inline pump diesel engines, unit pump diesel engines, and high-pressure common rail diesel engines.

[0039] In some embodiments, the oil depot inlet circuit includes a first manual valve, a first fuel filter assembly, a fuel consumption meter, an oil depot inlet temperature sensor, an oil depot inlet pressure sensor, and a first check valve, which are arranged between the laboratory fuel inlet and the fuel variable frequency pump and connected in sequence.

[0040] Specifically, in this embodiment, the oil depot inlet serves as the laboratory fuel inlet, supplying fuel with a standard threaded connection and a conical seal. The first manual valve allows for bidirectional flow and shut-off, and can be manually opened or closed. The first fuel filter assembly filters impurities from the oil depot inlet, preventing jamming of high-speed precision components in the fuel system. The fuel consumption meter measures the diesel engine's fuel consumption. The oil depot inlet temperature sensor measures the temperature of the oil after the fuel consumption meter. The oil depot inlet pressure sensor measures the pressure of the oil after the fuel consumption meter. The first check valve acts as a one-way valve, restricting only the direction of fuel flow; pressure changes in the fuel system do not affect the flow.

[0041] The oil entering the oil depot passes through the first manual valve, the first fuel filter assembly, the fuel consumption meter, the oil depot inlet temperature sensor (T), the oil depot inlet pressure sensor (P), and the first check valve to form the oil depot inlet circuit, which then converges to the fuel variable frequency pump.

[0042] In some embodiments, the diesel engine return oil circuit includes a second hand valve, a first oil-gas separator, a second fuel filter assembly, a diesel engine return oil pressure sensor (P), an overflow valve, a first cooling heat exchanger, a diesel engine return oil temperature sensor (T), and a second check valve, which are arranged between the diesel engine return oil outlet and the fuel variable frequency pump and connected in sequence.

[0043] A first pressure relief valve is provided on the oil line connecting the oil-gas separator and the second fuel filter assembly.

[0044] Specifically, the diesel engine return oil outlet connects to the fuel supply system, enabling precise and synchronous fuel consumption measurement. It features a standard threaded connection and a conical seal. A second manual valve allows for bidirectional flow and shut-off, and can be manually opened or closed. A first oil-gas separator automatically removes air bubbles from the high-pressure compressed fuel return oil. A second fuel filter assembly filters impurities from the diesel engine return oil, preventing jamming of high-speed precision components in the fuel system. A diesel engine return oil pressure sensor measures the return oil pressure. An overflow valve is also included. The system includes: a low-pressure direct-acting relief valve for controlling the pressure before the diesel engine return oil valve; a brazed heat exchanger for cooling the diesel engine return oil when the return oil temperature is high; a diesel engine return oil temperature sensor for measuring the return oil temperature; a second check valve for unidirectional flow and reverse cut-off, restricting only the direction of fuel flow, without affecting flow due to pressure changes in the oil circuit; and a first pressure relief valve that opens when the diesel engine return oil pressure exceeds a preset value.

[0045] The diesel engine return oil passes through the second manual valve, oil-gas separator, second fuel filter assembly, diesel engine return oil pressure sensor (T), overflow valve, first cooling heat exchanger, diesel engine return oil temperature sensor (P), and second check valve to form the diesel engine return oil circuit, which then converges to the fuel variable frequency pump.

[0046] In some embodiments, the diesel engine fuel inlet circuit includes a third hand valve, a diesel engine fuel inlet pressure sensor, a diesel engine fuel inlet temperature sensor, and a pressure reducing valve connected in sequence.

[0047] The other end of the third hand valve is connected to the diesel engine's fuel inlet.

[0048] The other end of the pressure reducing valve is connected to the first port of the diesel engine inlet three-way valve. The second and third ports of the diesel engine inlet three-way valve are respectively connected to the second cooling heat exchanger and the heating heat exchanger. The other ends of the second cooling heat exchanger and the heating heat exchanger are connected to the fuel variable frequency pump through the second oil-gas separator.

[0049] The heating heat exchanger is connected to the water bath heater via a hot water return pressure sensor (P). The water heated by the water bath heater enters the heating heat exchanger to form a circulating heating water loop.

[0050] Specifically, the diesel engine inlet valve supplies constant-temperature and constant-pressure fuel to the diesel engine; it features a standard threaded connection and a conical seal. The third manual valve allows for bidirectional flow and shut-off, and can be manually opened or closed. A diesel engine inlet pressure sensor measures the pressure at the fuel inlet. A diesel engine inlet temperature sensor measures the temperature at the fuel inlet. A pressure reducing valve regulates the fuel inlet pressure, reducing the pressure after the variable frequency fuel pump to ensure stable pressure. A three-way diesel engine inlet valve adjusts the ratio of cooled to heated fuel to achieve stable fuel inlet temperature control. A second cooling heat exchanger cools the diesel engine inlet fuel. A heating heat exchanger heats the diesel engine inlet fuel. A water bath heater uses water as a medium to heat the diesel engine inlet fuel, serving as the fuel heating heat source. A hot water return pressure sensor detects the presence of hot water and quantitatively measures the hot water flow rate.

[0051] In some embodiments, the cooling water circulation path includes a cooling water inlet, which is connected to a first cooling heat exchanger, a second cooling heat exchanger, a third cooling heat exchanger and a diesel engine oil return three-way valve, respectively. The outlet end of the third cooling heat exchanger is connected to the cooling water outlet, and the outlet end of the third cooling heat exchanger is also equipped with a cooling water return pressure sensor.

[0052] The second port of the diesel engine return three-way valve is connected to the first cooling heat exchanger;

[0053] The third port of the diesel engine return three-way valve is connected to the third cooling heat exchanger and the cooling water return pressure sensor.

[0054] Specifically, the diesel engine return oil three-way valve is installed at the inlet and outlet of the first cooling heat exchanger. By adjusting the opening of the three-way valve, the proportion of cooling water passing through the plate heat exchanger is controlled to cool the diesel engine return oil. The cooling water inlet, with a standard threaded connection and conical seal, supplies cooling water and ensures the circulation of cooling water in the diesel system. It also has a standard threaded connection and a conical seal. The cooling water return pressure sensor detects the presence of cooling water and measures the flow rate. The fuel variable frequency pump pressurizes the diesel engine return oil and diesel fuel from the fuel tank and supplies it to the diesel engine. The speed control method is a robust PID controller: when the diesel engine inlet pressure decreases, the speed increases; when the diesel engine inlet pressure increases, the speed decreases. The third cooling heat exchanger continues to operate even when the diesel fuel does not flow, cooling the high-temperature fuel with excessive pressure after the fuel variable frequency pump.

[0055] The diesel engine's fuel inlet temperature range is limited by the temperatures of the cooling water and the hot water in the water bath heater. The fuel temperature after passing through the cooling heat exchanger is primarily determined by the cooling water temperature, which is supplied by a laboratory chiller. The temperature and pressure of the supplied cooling water can be manually adjusted within the equipment's adjustable range and remain stable after adjustment. Similarly, the fuel temperature after passing through the heating heat exchanger is primarily determined by the hot water temperature in the water bath heater, which is also supplied by the water bath heater. The hot water temperature can be manually adjusted within the equipment's adjustable range and remains stable after adjustment. The pressure is determined by a fixed-displacement water pump.

[0056] It should be noted that the fuel variable frequency pump is a gear pump with adjustable speed, the cooling water temperature and pressure supplied by the cooling water inlet can be set and remain stable after setting, the water bath heater is a hot water circulating system, the hot water temperature can be set and remains stable after setting, and the hot water pressure is constant and cannot be adjusted.

[0057] In some implementations, the fuel variable frequency pump is connected to a third cooling heat exchanger to form a circulation loop, and a second pressure relief valve is also provided on the circulation loop.

[0058] Specifically, a second pressure relief valve is provided after the fuel variable frequency pump. When the diesel engine is not working and the fuel variable frequency pump is working normally, if the pressure after the fuel variable frequency pump is greater than the set value of the second pressure relief valve, the second pressure relief valve opens. The fuel after the fuel variable frequency pump returns to the front of the fuel variable frequency pump through the second pressure relief valve and the third cooling heat exchanger. During this process, the fuel is cooled. The second pressure relief valve plays a role in protecting the fuel variable frequency pump and preventing the motor from burning out due to overload and blockage. The third cooling heat exchanger cools the high-temperature fuel after the fuel variable frequency pump and prevents the fuel temperature from continuing to rise.

[0059] In some implementations, such as Figure 2 As shown, it also includes a high-speed pulse signal acquisition module, a thermocouple signal acquisition module, an analog signal acquisition module, a controller, an analog output module, a frequency converter, a pressure reducing valve actuator, a diesel engine return three-way valve actuator, and a diesel engine inlet three-way valve actuator;

[0060] The high-speed pulse signal acquisition module is connected to a diesel engine speed sensor to acquire the diesel engine speed;

[0061] The thermocouple signal acquisition module is connected to the oil depot inlet temperature sensor, the diesel engine inlet temperature sensor, and the diesel engine return temperature sensor to acquire the temperature of the flow path where each sensor is located.

[0062] The analog signal acquisition module is connected to the oil depot inlet pressure sensor, the diesel engine inlet pressure sensor, the diesel engine return pressure sensor, the diesel engine throttle opening sensor, the cooling water return pressure sensor, and the hot water return pressure sensor, respectively.

[0063] The output terminals of the high-speed pulse signal acquisition module, thermocouple signal acquisition module, and analog signal acquisition module are connected to the controller, which in turn connects to the analog output module to control the output of the analog signal.

[0064] The output terminals of the analog output module are connected to the frequency converter, the diesel engine return three-way valve actuator (electric type), and the diesel engine inlet three-way valve actuator (electric type), respectively. The frequency converter controls the speed of the fuel variable frequency pump according to the received analog output signal. The diesel engine return three-way valve actuator adjusts the valve opening of the diesel engine return three-way valve according to the received analog output signal to achieve the function of regulating the diesel engine return oil temperature. The diesel engine inlet three-way valve actuator adjusts the valve opening of the diesel engine inlet three-way valve according to the received analog output signal to achieve the function of regulating the diesel engine inlet oil temperature. The pressure reducing valve actuator (electric type) adjusts the valve position of the pressure reducing valve according to the received analog output signal to achieve the function of regulating the diesel engine inlet oil pressure.

[0065] Specifically, the diesel engine speed sensor is a magnetoelectric sensor that senses the crankshaft signal disk signal. It emits a high-level signal when sensing the height of a tooth and no signal when sensing the root of a tooth. The diesel engine throttle opening signal sensor detects throttle openings from 0% to 100%, corresponding to a DC signal of 0.5V to 4.5V. The high-speed pulse signal acquisition module converts high-speed pulses into a digital quantity of a certain number of pulses per second. The thermocouple signal acquisition module amplifies and filters the weak electrical signals from thermocouples and converts them into digital quantities. The analog signal acquisition module converts analog signals into digital quantities. The controller, based on the input signal, calculates the given digital output value using an algorithm. The analog output module converts the digital output value back into an analog output. The frequency converter... The actuators control the speed of the variable frequency fuel pump by receiving analog signals and adjusting the pump speed accordingly. The corresponding relationship is: DC 0V to 5V corresponds to an opening of 100rpm to 3000rpm. Similarly, the actuators control the diesel engine inlet three-way valve by receiving analog signals and adjusting the valve opening accordingly. The corresponding relationship is: DC 0V to 5V corresponds to an opening of 0% to 100%. The actuators control the diesel engine return three-way valve by receiving analog signals and adjusting the valve opening accordingly. The corresponding relationship is: DC 0V to 5V corresponds to an opening of 0% to 100%. Finally, the actuators control the pressure reducing valve by receiving analog signals and adjusting the valve position accordingly. The corresponding relationship is: DC 0V to 5V corresponds to a valve position of 0% to 100%.

[0066] Secondly, this embodiment provides a control method based on the above-described diesel engine fuel supply condition control system, the control method comprising:

[0067] In response to controlling the diesel engine inlet fuel temperature, the diesel engine return fuel and the fuel tank inlet fuel are combined at the fuel variable frequency pump. The combined fuel is pressurized by the fuel variable frequency pump and divided into two paths. One path of fuel passes through a second cooling heat exchanger cooled by cooling water, and the other path of fuel passes through a heating heat exchanger heated by hot water. Both paths flow through the diesel engine inlet three-way valve. The PID control algorithm adjusts the valve position of the diesel engine inlet three-way valve to control the mixing ratio of cooling fuel and heating fuel, thereby controlling the diesel engine fuel supply temperature.

[0068] Specifically, the oil temperature in the oil depot is generally unaffected by the storage environment, but the diesel engine return oil temperature is significantly affected by the diesel engine's operating conditions. When the return oil temperature is too high, exceeding the adjustment capacity of the laboratory fuel supply system, it is necessary to cool the diesel engine return oil temperature to a certain extent. Figure 3It is known that the fuel from the diesel engine return oil and the fuel from the fuel depot, after merging, is pressurized by the variable frequency fuel pump. The pressurized fuel is then divided into two paths: one path passes through a cooling heat exchanger cooled by cooling water, and the other path passes through a heating heat exchanger heated by hot water. Both paths flow through the diesel engine inlet three-way valve. By adjusting the valve position of the diesel engine inlet three-way valve in real time, the mixing ratio of cooling fuel and heating fuel is controlled, achieving automatic and stable control of the diesel engine inlet fuel temperature. When the diesel engine inlet fuel temperature is higher than the set value, the diesel engine inlet three-way regulating valve actuates, increasing the proportion of cooling fuel flow and decreasing the proportion of heating fuel flow, thereby lowering the fuel temperature. When the diesel engine inlet fuel temperature is lower than the set value, the diesel engine inlet three-way regulating valve actuates, decreasing the proportion of cooling fuel flow and increasing the proportion of heating fuel flow, thereby raising the fuel temperature. The method for automatic and stable control of the diesel engine inlet fuel flow direction and inlet fuel temperature is as follows: Figure 3 As shown.

[0069] Note: The diesel engine's inlet fuel temperature range is limited by the cooling water temperature and the hot water temperature of the water bath heater. The fuel temperature after flowing through the cooling heat exchanger is mainly determined by the cooling water temperature, which is provided by a laboratory chiller unit. The temperature and pressure of the supplied cooling water can be manually adjusted within the equipment's adjustment range and remain stable after adjustment. The fuel temperature after flowing through the heating heat exchanger is mainly determined by the hot water temperature in the water bath heater, which is also provided by the water bath heater. The temperature of the supplied hot water can be manually adjusted within the equipment's adjustment range and remains stable after adjustment. The pressure is determined by a fixed-displacement water pump.

[0070] In some implementations, in response to controlling the diesel engine inlet pressure, the diesel engine inlet pressure and diesel engine return pressure are combined at the fuel variable frequency pump. The combined pressure is boosted by the fuel variable frequency pump, and the boosted fuel is divided into two paths: one path passes through the second cooling heat exchanger, and the other path passes through the heating heat exchanger. Both paths flow through the diesel engine inlet three-way valve, the pressure reducing valve, and the diesel engine inlet pressure sensor. The valve position of the pressure reducing valve is adjusted by a PID control algorithm to regulate the diesel engine fuel supply pressure.

[0071] Specifically, in the oil depot inlet circuit, the pressure P0 from the oil depot inlet pressure sensor is influenced by the natural pressure generated by the oil depot's height, the negative pressure before the pump generated by the variable fuel pump, and pressure losses in the pipelines and components. In the diesel engine return oil circuit, the pressure P1 from the diesel engine return oil pressure sensor is influenced by the return oil pressure generated by the diesel engine, the negative pressure before the pump generated by the variable fuel pump, and pressure losses in the pipelines and components. The pressure P2 before the variable fuel pump is generated by the convergence of the oil inlet P0 and the diesel engine return P1. The pressure P3 after the variable fuel pump is generated by the boosting of P2 by the variable fuel pump. The pressurized fuel is divided into two paths: one through a cooling heat exchanger and the other through a heating heat exchanger. Both paths flow through the diesel engine inlet three-way valve, the pressure reducing valve, and the diesel engine inlet pressure sensor. The pressure before the pressure reducing valve is P4, and the pressure after the pressure reducing valve is P5. Ideally, the pressure reducing valve should maintain a constant outlet pressure P5 regardless of changes in inlet pressure, flow rate, or increased outlet load. P5 corresponds to the pressure of the diesel engine inlet pressure sensor. However, in reality, the outlet pressure P5 varies with changes in inlet pressure and flow rate, or with increased load. Therefore, adjusting the pressure reducing valve actuator can only stabilize the diesel engine inlet pressure within a certain range under all operating conditions. The diesel engine inlet flow direction and pressure control method are as follows: Figure 4 As shown.

[0072] To achieve precise control of the diesel engine's inlet pressure under all operating conditions, a robust PID control algorithm is required. This method relies less on the specific system model for inlet pressure adjustment. The input signal to the robust PID algorithm is the diesel engine inlet pressure P5, and the controlled object is the fuel variable frequency pump. When P5 increases, the fuel variable frequency pump speed is automatically reduced; when P5 decreases, the fuel variable frequency pump speed is automatically reduced. By tuning the PID parameters, specific requirements for rise time, overshoot, settling time, and steady-state error can be met. The diesel engine inlet flow direction and inlet pressure control methods are as follows: Figure 4 As shown, the diesel engine's inlet pressure under all operating conditions is the result of the combined action of the fuel inverter pump's downstream pressure and the pressure reducing valve. The diesel engine's return pressure is the result of the diesel engine's own return capacity, the overflow valve, and the fuel inverter pump. Therefore, this method places higher demands on the robust control strategy of the fuel inverter pump's speed. On the one hand, it must ensure that the return oil path is unobstructed, preventing the return oil path from becoming blocked and causing an increase in return oil pressure. On the other hand, it requires that the downstream pressure of the pump must be greater than the input pressure of the pressure reducing valve; otherwise, the diesel engine's inlet pressure will decrease.

[0073] It should be noted that the PID control algorithm described in this embodiment is a conventional control method well known to those skilled in the art. This embodiment achieves precise control of fuel inlet temperature and pressure through the designed PID control method. No improvement has been made to the PID control algorithm itself, and it will not be described further here.

[0074] In some implementations, in response to the diesel engine return oil pressure being greater than the set threshold of the first pressure relief valve, the pressure relief valve is controlled to open, allowing high-pressure diesel fuel to flow out of the test chamber fuel supply device;

[0075] In response to the diesel engine return oil pressure being less than the set threshold of the first pressure relief valve, the diesel engine return oil pressure is controlled by the overflow valve.

[0076] Specifically, by Figure 1 It can be seen that when the diesel engine return oil pressure is greater than the set value of the first pressure relief valve, the first pressure relief valve opens, allowing high-pressure diesel fuel to flow out of the test chamber fuel supply device. When the return oil pressure is below the set value of the first pressure relief valve, the magnitude of the diesel engine return oil pressure is controlled by the overflow valve. The overflow valve keeps the pressure before the valve basically constant, ensuring the stability of the diesel engine return oil pressure. The magnitude of the return oil pressure can be manually adjusted by the overflow valve. It should be noted that the set threshold value described in this embodiment can be a calibrated standard value, or it can be flexibly set by those skilled in the art based on the actual field conditions. No further limitations are made here.

[0077] Depend on Figure 1 It is known that the diesel engine return oil temperature is detected by the return oil thermocouple temperature sensor. When the return oil temperature is higher than the set value, the diesel engine return oil three-way valve activates, allowing some cooling water to flow through the cooling exchanger to cool the diesel engine return oil, while the other part of the cooling water flows directly to the cooling water return pipe. When the return oil temperature is lower than the set value, the diesel engine return oil three-way valve does not activate, allowing all the cooling water to flow directly to the chilled water return pipe, and the diesel engine return oil is not cooled.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

[0079] The embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this application should be included within the protection scope of this application.

Claims

1. A diesel engine fuel supply condition control system, characterized in that: This includes the oil depot's inlet oil circuit, the diesel engine's return oil circuit, the diesel engine's inlet oil circuit, the cooling water circulation circuit, and the fuel variable frequency pump; The oil depot's inlet oil line and the diesel engine's return oil line are connected in parallel to the fuel variable frequency pump, and then connected to the diesel engine's inlet oil line via the fuel variable frequency pump. The fuel variable frequency pump combines the pressurized oil depot fuel and the diesel engine's return oil, and then goes to the diesel engine end via the diesel engine's inlet oil line. The cooling water circulation path is connected to the diesel engine return oil path, the diesel engine inlet oil path and the fuel variable frequency pump respectively. The diesel engine inlet oil path is equipped with a diesel engine inlet three-way valve. The diesel engine inlet three-way valve is controlled by the PID control algorithm to adjust the ratio of cooled fuel and heated fuel, thereby controlling the diesel engine fuel supply temperature. The diesel engine fuel inlet circuit is also equipped with a pressure reducing valve connected to the diesel engine fuel inlet three-way valve. The valve position of the pressure reducing valve is adjusted by a PID control algorithm to regulate the diesel engine fuel supply pressure.

2. A diesel engine fuel supply condition control system according to claim 1, characterized in that: The oil depot's oil inlet circuit includes a first manual valve, a first fuel filter assembly, a fuel consumption meter, an oil depot inlet temperature sensor, an oil depot inlet pressure sensor, and a first check valve, which are installed between the laboratory fuel inlet and the fuel variable frequency pump and connected in sequence.

3. A diesel engine fuel supply condition control system according to claim 2, characterized in that: The diesel engine return oil circuit includes a second hand valve, a first oil-gas separator, a second fuel filter assembly, a diesel engine return oil pressure sensor, an overflow valve, a first cooling heat exchanger, a diesel engine return oil temperature sensor, and a second check valve, which are located between the diesel engine return oil outlet and the fuel variable frequency pump and connected in sequence. A first pressure relief valve is provided on the oil line connecting the first oil-gas separator and the second fuel filter assembly.

4. A diesel engine fuel supply condition control system according to claim 3, characterized in that: The diesel engine fuel inlet circuit includes a third manual valve, a diesel engine fuel inlet pressure sensor, a diesel engine fuel inlet temperature sensor, and a pressure reducing valve connected in sequence. The other end of the third hand valve is connected to the diesel engine's fuel inlet. The other end of the pressure reducing valve is connected to the first port of the diesel engine inlet three-way valve. The second and third ports of the diesel engine inlet three-way valve are respectively connected to the second cooling heat exchanger and the heating heat exchanger. The other ends of the second cooling heat exchanger and the heating heat exchanger are connected to the fuel variable frequency pump through the second oil-gas separator. The heating heat exchanger is connected to the water bath heater via a hot water return pressure sensor. The water heated by the water bath heater enters the heating heat exchanger to form a circulating heating water loop.

5. A diesel engine fuel supply condition control system according to claim 4, characterized in that: The diesel engine return oil circuit also includes a diesel engine return oil three-way valve; The cooling water circulation path includes a cooling water inlet and a cooling water return outlet. The cooling water inlet is connected to the inlet of the first cooling heat exchanger, the inlet of the second cooling heat exchanger, and the inlet of the third cooling heat exchanger, respectively. The cooling water return outlet is connected to the third port of the diesel engine return three-way valve, the outlet of the second cooling heat exchanger, and the outlet of the third cooling heat exchanger, respectively. The first port of the diesel engine oil return three-way valve is connected to the inlet of the first cooling heat exchanger, the second port is connected to the outlet of the first cold water heat exchanger, and the third port is connected to the main return cooling water pipeline. The first and second ports of the diesel engine oil return three-way valve are the inlet of cooling water, and the third port is the outlet of cooling water. A cooling water return pressure sensor is installed on the main cooling water return pipeline.

6. A diesel engine fuel supply condition control system according to claim 5, characterized in that: The fuel variable frequency pump is connected to the third cooling heat exchanger to form a circulation loop, and a second pressure relief valve is also provided on the circulation loop.

7. A diesel engine fuel supply condition control system according to claim 6, characterized in that: It also includes a high-speed pulse signal acquisition module, a thermocouple signal acquisition module, an analog signal acquisition module, a controller, an analog output module, a frequency converter, a pressure reducing valve actuator, a diesel engine return three-way valve actuator, and a diesel engine inlet three-way valve actuator; The high-speed pulse signal acquisition module is connected to a diesel engine speed sensor to acquire the diesel engine speed; The thermocouple signal acquisition module is connected to the oil depot inlet temperature sensor, the diesel engine inlet temperature sensor, and the diesel engine return temperature sensor to acquire the temperature of the flow path where each sensor is located. The analog signal acquisition module is connected to the oil depot inlet pressure sensor, the diesel engine inlet pressure sensor, the diesel engine return pressure sensor, the diesel engine throttle opening sensor, the cooling water return pressure sensor, and the hot water return pressure sensor, respectively. The output terminals of the high-speed pulse signal acquisition module, thermocouple signal acquisition module, and analog signal acquisition module are connected to the controller, which in turn connects to the analog output module to control the output of the analog signal. The output terminals of the analog output module are connected to the frequency converter, the pressure reducing valve actuator, the diesel engine return three-way valve actuator, and the diesel engine inlet three-way valve actuator, respectively. The frequency converter controls the speed of the fuel variable frequency pump according to the received analog output signal. The pressure reducing valve actuator controls the opening degree of the pressure reducing valve according to the received analog output signal. The diesel engine return three-way valve actuator adjusts the valve opening degree of the diesel engine return three-way valve according to the received analog output signal. The diesel engine inlet three-way valve actuator adjusts the valve opening degree of the diesel engine inlet three-way valve according to the received analog output signal.

8. A control method for a diesel engine fuel supply condition control system according to any one of claims 1-7, characterized in that, The control method includes: In response to controlling the diesel engine inlet fuel temperature, the diesel engine return fuel and the fuel tank inlet fuel are combined at the fuel variable frequency pump. The combined fuel is pressurized by the fuel variable frequency pump and divided into two paths. One path of fuel passes through a second cooling heat exchanger cooled by cooling water, and the other path of fuel passes through a heating heat exchanger heated by hot water. Both paths flow through the diesel engine inlet three-way valve. The PID control algorithm adjusts the valve position of the diesel engine inlet three-way valve to control the mixing ratio of cooling fuel and heating fuel, thereby controlling the diesel engine fuel supply temperature.

9. The control method according to claim 8, characterized in that: In response to controlling the diesel engine inlet pressure, the diesel engine inlet pressure and diesel engine return pressure are combined by the fuel variable frequency pump. The combined pressure is boosted by the fuel variable frequency pump, and the boosted fuel is divided into two paths. One path passes through the second cooling heat exchanger, and the other path passes through the heating heat exchanger. Both paths flow through the diesel engine inlet three-way valve, pressure reducing valve, and diesel engine inlet pressure sensor. The pressure reducing valve position is adjusted by the PID control algorithm to regulate the diesel engine fuel supply pressure.

10. The control method according to claim 8, characterized in that: In response to the diesel engine return oil pressure exceeding the set threshold of the first pressure relief valve, the pressure relief valve is opened to allow high-pressure diesel fuel to flow out to the test chamber oil storage. In response to the diesel engine return oil pressure being less than the set threshold of the first pressure relief valve, the diesel engine return oil pressure is controlled by the overflow valve.

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