An intake air preheating system for cold starting of a diesel engine

Abstract

The present specification discloses an intake preheating system for cold start of diesel engine, which comprises integrated upper plate, upper plate adapter plate, oil injector mounting seat, oil injector mounting hole, oil injector, oil injector pressure table, stud, auxiliary heating rod, auxiliary heating rod pressure block, wall temperature sensor, bracket mounting protrusion, heating plate threading hole, heating plate bracket, spoiler, heating plate pressure plate, main heating plate, engine intake pipeline and controller. The system uses low-pressure fuel spray of oil injector to impact high-temperature main heating plate to achieve ignition, enhances atomization, improves reaction rate, introduces spoiler to form backflow to improve stability of flame in high-speed airflow, can quickly increase intake temperature, shorten cold start time, and reduce fuel and power consumption. The system flexibly adjusts oil injection strategy according to different working conditions, is compact in design, convenient to integrate, low in manufacturing and maintenance cost, and suitable for application in heavy-duty diesel engine.

Description

Technical Field

[0001] This invention relates to the field of diesel engine cold start technology, and more specifically, to an intake air preheating system for cold starting of a diesel engine. Background Technology

[0002] Diesel engines face difficulties in cold starting in extremely cold environments, especially below -20°C. This is due to low compression top dead center temperature, severe low-speed air leakage, and poor fuel atomization and evaporation. Various cold-start auxiliary measures are necessary, including fuel heating, intake air preheating, engine block preheating, and battery insulation. In operating environments ranging from -40°C to -20°C, intake air preheating can effectively improve in-cylinder thermal conditions in a short time, enhancing cold-start performance and ensuring emergency starting for heavy-duty trucks and special vehicles.

[0003] Studies have shown that commonly used intake preheating devices include electric heaters mounted on the intake manifold, glow plugs, thermally charged ceramic (PTC) starters, and glow plugs installed in the cylinder. Flame preheating is suitable for scenarios with large intake airflow and extremely low temperatures, offering significant advantages for rapid and reliable cold starts of heavy-duty diesel engines. However, traditional glow plugs have long start-up times, low fuel vaporization and combustion efficiency, and are prone to coking and carbon buildup. Furthermore, their system control freedom is low, and their robustness is poor, limiting their preheating effect and operating temperature limits. Electric heaters, on the other hand, have high energy consumption, and PTC starters are expensive.

[0004] Therefore, there is an urgent need to develop an air intake preheating device that can heat up quickly, consume little energy, be cost-effective, be easy to control, and be reliable in operation. Summary of the Invention

[0005] This specification provides an intake air preheating system for cold starting of a diesel engine, which overcomes at least one technical problem existing in the related art.

[0006] According to embodiments of this specification, an intake air preheating system for cold starting a diesel engine is provided, comprising an integrated upper plate, an upper plate adapter plate, an injector mounting base, an injector mounting hole, an injector, an injector pressure plate, a stud, an auxiliary heating rod, an auxiliary heating rod pressure block, a wall temperature sensor, a bracket mounting protrusion, a heating plate wiring hole, a heating plate bracket, a spoiler, a heating plate pressure plate, a main heating plate, an engine intake air pipe, and a controller.

[0007] The integrated upper plate is fixed to the upper plate adapter plate, which is in turn fixed to the engine intake manifold. The integrated upper plate has an injector mounting bracket on one side of its upper surface. The injector mounting bracket contains an injector mounting hole. The front end of the injector is pressed into the mounting hole at a preset angle. The injector's spray axis forms an acute angle with the intake direction of the engine intake manifold. An injector pressure plate is fitted onto the rear end of the injector. The pressure plate is fixed to the integrated upper plate by studs and bolts. An auxiliary heating rod is inserted into the injector mounting bracket near the front end of the injector. An auxiliary heating rod clamp is provided at one end of the heating rod. A wall temperature sensor is provided on the surface of the injector mounting base above the auxiliary heating rod. A slot is provided on the lower surface of the integrated upper plate away from the injector. A bracket mounting protrusion is provided above the slot on the integrated upper plate. A heating plate wiring through hole is provided on the side of the integrated upper plate away from the injector. The upper plate adapter plate is a hollow plate, located below the integrated upper plate, and is fixed to the integrated upper plate with bolts. The heating plate bracket is inverted T-shaped on the front and H-shaped on the side, integrally formed, with the upper U-shaped part vertically inserted into the slot of the integrated upper plate, and is fixed by rotating... The bolts inside the mounting protrusions of the heating plate bracket secure the heating plate bracket to the integrated upper plate. A spoiler of preset height is installed in the middle of the heating plate bracket, and horizontal holes are pre-drilled in the lower U-shaped section. The lower U-end of the heating plate bracket is fixed to the heating plate pressure plate with bolts. One end of the main heating plate is horizontally inserted into the pre-drilled hole at the lower end of the heating plate bracket, while the other end is located below the integrated upper plate. The heating plate bracket and the heating plate pressure plate press the main heating plate tightly together. The main heating plate's wires pass through the heating plate wiring hole in the integrated upper plate and connect to the AC power supply. Sensor mounting holes are pre-drilled on the engine intake manifold for sensor installation. The position of the orifice is collinear with the injector mounting hole along the injector spray axis. It is equipped with an intake air temperature sensor, an intake air pressure sensor, an intake air flow sensor, and an oxygen concentration sensor to obtain intake air temperature, pressure, flow, or wind speed as input signals for the controller. The controller is integrated into the vehicle's electronic control unit. Based on the input signals and a pre-calibrated ignition control curve, it looks up the optimal injection frequency and injection pulse width to obtain the optimal injection frequency and injection pulse width. It also performs real-time feedback control based on the intake air temperature and air-fuel ratio in the preheated engine intake manifold until the engine speed increases and the fluctuation rate decreases, thus completing the cold start process.

[0008] Optionally, the integrated upper plate and the upper plate adapter plate are sealed with a high-temperature resistant O-ring.

[0009] Optionally, the injector is a PFI injector, with the spray axis at a 45° angle to the horizontal direction and the injection pressure at 3 to 5 bar.

[0010] Optionally, the upper plate adapter is welded to the engine intake pipe.

[0011] Optionally, the main heating plate is made of high-temperature resistant silicon nitride ceramic with a rated power of 450W.

[0012] The beneficial effects of the embodiments in this specification are as follows:

[0013] This specification provides an intake air preheating system for cold starts of diesel engines. Fuel spray is injected through an injector into a heating plate in the intake manifold. The fuel spray impacts the high-temperature heating plate wall, igniting the fuel, enhancing atomization, and increasing the reaction rate. The fuel injection uses a PFI injector for low-pressure injection, which improves control precision, ensures atomization effect, and reduces the cost of the fuel supply system. The heating plate is made of high-temperature resistant silicon nitride ceramic, resulting in short start-up time and low cost. Simultaneously, to improve flame stability in high-speed airflow, a spoiler is introduced to create a recirculation effect, reducing local wind speed and forming a large recirculation zone. This promotes fuel evaporation and fuel-air mixing, which is beneficial for continuous ignition and flame stability under high wind speed and high flow conditions. The controller uses sensors in the system to control the intake air temperature in real time. It can flexibly select the optimal injection strategy for different operating conditions, performing feedforward and feedback control to complete the cold start process. This high degree of control allows for rapid increase of intake air temperature, shortens cold start time, and reduces fuel and energy consumption. The system has a compact design, making it easy to integrate into the engine intake manifold. It also has low manufacturing and maintenance costs, making it suitable for use in the cold start systems of heavy-duty diesel engines.

[0014] The innovative aspects of the embodiments in this specification are as follows:

[0015] 1. In this specification, ignition is achieved by low-pressure fuel spray impacting the wall of a high-temperature heating plate. The Leiden-Frost effect is used to break up and enhance atomization and evaporation, thereby improving the low-temperature reaction rate. The fuel is injected at low pressure using a PFI injector, which improves control accuracy, ensures atomization effect, and reduces the cost of the fuel supply system. The heating plate is made of high-temperature resistant silicon nitride ceramic, which has a short start-up time, a surface temperature of up to 1200°C, and low cost. It is reliable in operation and avoids damage due to dry burning, which is one of the innovative points of the embodiments in this specification.

[0016] 2. In this specification, active flow control is achieved by setting up spoilers, and fuel is injected against the wind direction. This reduces local wind speed, forms a large-area recirculation zone, promotes fuel evaporation and fuel-air mixing, which is beneficial for continuous ignition and flame stability under high wind speed and high flow conditions. It also rapidly increases the intake air temperature in a short time, which is one of the innovative points of the embodiments in this specification.

[0017] 3. In this specification, the introduction of a low-power auxiliary heating rod into the injector housing and the control of a suitable wall temperature can ensure the normal operation of the injector under low-temperature conditions, which is one of the innovative points of the embodiments in this specification.

[0018] 4. In this specification, the ECU controller flexibly selects the optimal fuel injection strategy for different operating conditions, performs feedforward and feedback control to complete the cold start process, and has a high degree of control freedom. This is conducive to achieving a balance between temperature rise rate and combustion efficiency, which can shorten the intake air preheating time and reduce fuel and electricity consumption. This is one of the innovative points of the embodiments in this specification.

[0019] 5. The system in this specification is small in size, compact in design, and has few parts, making it easy to integrate into the engine intake manifold. It also has low manufacturing and maintenance costs and is easy to apply in the cold start system of heavy-duty diesel engines. This is one of the innovative features of the embodiments in this specification. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments or related technologies of this specification, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of an intake air preheating system for cold starting a diesel engine, provided as an embodiment of this specification.

[0022] In the diagram, 1-integrated upper plate, 2-upper plate adapter plate, 3-injector mounting base, 4-injector mounting hole, 5-injector, 6-injector pressure plate, 7-stud, 8-auxiliary heating rod, 9-auxiliary heating rod pressure block, 10-wall temperature sensor, 11-bracket mounting protrusion, 12-heating plate wiring hole, 13-heating plate bracket, 14-spoiler, 15-heating plate pressure plate, 16-main heating plate, 17-engine intake pipe, 18-controller, 19-spray axis, 20-vertical distance of main heating plate, 21-horizontal distance of main heating plate. Detailed Implementation

[0023] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and 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.

[0024] It should be noted that the terms "comprising" and "having," and any variations thereof, in the embodiments and drawings of this specification are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0025] This specification discloses an intake air preheating system for cold starting of a diesel engine, which will be described in detail below.

[0026] Figure 1 This is a schematic diagram of an intake air preheating system for cold starting a diesel engine, provided as an embodiment of this specification. Figure 1 As shown, an intake preheating system for cold starts includes an integrated upper plate 1, an upper plate adapter plate 2, an injector mounting base 3, an injector mounting hole 4, an injector 5, an injector pressure plate 6, a stud 7, an auxiliary heating rod 8, an auxiliary heating rod pressure block 9, a wall temperature sensor 10, a bracket mounting protrusion 11, a heating plate wiring hole 12, a heating plate bracket 13, a spoiler 14, a heating plate pressure plate 15, a main heating plate 16, an engine intake manifold 17, and a controller 18.

[0027] The integrated upper plate 1 is fixed on the upper plate adapter plate 2, and the upper plate adapter plate 2 is fixed on the engine intake pipe 17.

[0028] In one specific embodiment, the integrated upper plate 1 and the upper plate adapter plate 2 are sealed by a high-temperature resistant O-ring.

[0029] In one specific embodiment, the upper plate adapter plate 2 is welded to the engine intake pipe 17. The function of the upper plate adapter plate is to fix the integrated upper plate to the engine intake pipe.

[0030] The integrated upper plate 1 has an injector mounting seat 3 on one side of its upper surface. The injector mounting seat 4 has an injector mounting hole 4 inside. The front end of the injector 5 is pressed into the injector mounting hole 4 at a preset angle. The spray axis of the injector is at an acute angle to the air intake direction of the engine intake pipe.

[0031] In one specific embodiment, the injector 5 is a PFI injector, with the spray axis at a 45° angle to the horizontal direction. The injector 5 has four nozzles, uses diesel fuel, and has an injection pressure of 3–5 bar.

[0032] In one specific embodiment, the injector 5 and the injector mounting hole 4 are sealed by an O-ring.

[0033] The injector 5 has an injector pressure plate 6 mounted on its rear end. The injector pressure plate 6 is fixed to the integrated upper plate 1 by bolts 7. An auxiliary heating rod 8 is inserted into the injector mounting base 3 on the side near the front end of the injector 5. By introducing a low-power auxiliary heating rod into the injector mounting base and controlling the appropriate wall temperature, the normal operation of the injector can be ensured under low-temperature conditions. The auxiliary heating rod is only turned on when the ambient temperature is below the freezing point of diesel fuel.

[0034] An auxiliary heating rod clamping block 9 is provided on one end of the auxiliary heating rod 8 on the injector mounting base 3. The auxiliary heating rod is fixed radially and axially by the auxiliary heating rod clamping block. A wall temperature sensor 10 is provided on the surface of the injector mounting base 3 above the auxiliary heating rod 8.

[0035] In one specific embodiment, the wall temperature sensor 10 is a screw-type K-type thermocouple. A screw-type wall temperature sensor is mounted on the upper surface of the injector mounting base and connected to a temperature controller and relay to control the wall temperature.

[0036] In one specific embodiment, the rated power of the auxiliary heating rod 8 is 80W.

[0037] A slot is provided on the lower surface of the integrated upper plate 1 on the side away from the injector 5. A bracket mounting protrusion 11 is provided above the slot of the integrated upper plate 1. A heating plate wire through hole 12 is provided on the side of the integrated upper plate 1 away from the injector 5.

[0038] The power cord of the main heating plate 16 passes through the wire hole 12 and is connected to an external AC power source. The wire hole 12 is screwed into a sealing connector and fixed to the integrated upper plate 1.

[0039] The upper plate adapter plate 2 is a hollow plate, which is located below the integrated upper plate 1 and is fixed to the integrated upper plate 1 by bolts.

[0040] In one specific embodiment, all bolts connecting the integrated upper plate 1 are M4 type. All other connecting bolts are M6 type.

[0041] The heating plate bracket 13 is inverted T-shaped on the front and H-shaped on the side, and is integrally formed. The upper U-shaped part is vertically inserted into the slot of the integrated upper plate 1. The heating plate bracket 13 is fixed to the integrated upper plate 1 by screwing in the bolts in the bracket mounting protrusion 11. The protrusion is provided to drill threaded holes in the upper plate to fix the bracket.

[0042] A pre-set height spoiler 14 is provided in the middle of the heating plate bracket 13. By setting the spoiler for active flow control and using counter-wind fuel injection, the local wind speed can be reduced, forming a large-area recirculation zone, promoting fuel evaporation and fuel-air mixing, which is beneficial for continuous ignition and flame stability under high wind speed and high flow conditions, and can quickly increase the intake air temperature in a short time.

[0043] The lower U-shaped part has a pre-drilled hole in the horizontal direction, and the lower U-end of the heating plate bracket 13 is fixed to the heating plate pressure plate 15 by bolts.

[0044] One end of the main heating plate 16 is horizontally inserted into the pre-drilled hole at the lower end of the heating plate bracket 13, and the other end is located below the integrated upper plate 1. The heating plate bracket 13 and the heating plate pressure plate 15 press the main heating plate 16 together. The wires of the main heating plate 16 pass through the heating plate wire hole 12 of the integrated upper plate 1 and are connected to the AC power supply.

[0045] In one specific embodiment, the main heating plate 16 is made of high-temperature resistant silicon nitride ceramic with a rated power of 450W.

[0046] Ignition is achieved by impacting the high-temperature heating plate wall with low-pressure fuel spray. The Leiden-Frost effect is used to break up and enhance atomization and evaporation, thereby improving the low-temperature reaction rate. The fuel is injected at low pressure using a PFI injector, which can improve control accuracy, ensure atomization effect, and reduce the cost of the fuel supply system. The heating plate is made of high-temperature resistant silicon nitride ceramic, which has a short start-up time, a surface temperature of up to 1200℃, low cost, reliable operation, and can avoid damage due to dry burning.

[0047] The engine intake manifold 17 has a pre-drilled sensor mounting hole. The sensor mounting hole is located collinear with the injector mounting hole along the injector spray axis. An intake air temperature sensor, an intake air pressure sensor, an intake air flow sensor, and an oxygen concentration sensor are installed thereto, and the intake air temperature, pressure, flow rate, or wind speed are obtained as input signals for the controller.

[0048] Figure 1 In the design, the left side represents the low-temperature intake airflow, and the right side represents the preheated high-temperature airflow, which enters the combustion chamber of the engine cylinder. The geometric relative positions of the intake preheating device are as follows: the PFI injector is placed against the direction of the incoming flow, the spray axis 19 is at a 45° angle to the horizontal direction, the spoiler is located upstream of the main heating plate, the vertical distance 20 of the main heating plate is the distance between the lowest point of the heating plate bracket and the upper inner surface of the engine intake pipe, and the horizontal distance 21 of the main heating plate is the distance between the injection point on the upper surface of the main heating plate and the frontmost left side of the heating plate bracket. The injection point position on the main heating plate has an optimal range to maximize the ignition success rate and the most stable flame, which can be further optimized by adjusting the vertical and horizontal distances of the main heating plate. Various sensors are installed on the engine intake pipe 18. An intake air temperature sensor, an intake air pressure sensor, and an intake air flow sensor are installed before the intake preheating device to measure the preheated intake air temperature T. in Preheating the inlet air pressure P in Intake flow rate Q in Or intake air speed V inOne or more intake air temperature sensors and oxygen sensors are installed after the intake air preheating device to measure the intake air temperature T after preheating. out Preheated air-fuel ratio λ out Analog signals such as temperature, pressure, flow rate, and air-fuel ratio are input into the ECU to control the fuel injection strategy.

[0049] Before system installation, experimental calibration work needs to be carried out to determine the optimal fuel injection parameters, including the fuel injection frequency f, under different intake flow rates or wind speeds. inj And fuel injection pulse width T inj This allows the engine to achieve both a high rate of temperature rise and high combustion efficiency. A MAP diagram is then generated and stored in the ECU for feedforward and feedback control under different engine operating conditions.

[0050] The controller 18, integrated into the vehicle's electronic control unit, obtains the optimal injection frequency and injection pulse width by looking up a table based on the input signal and the pre-calibrated ignition control curve. It also performs real-time feedback control based on the intake air temperature and oxygen concentration in the preheated engine intake manifold 17 until the engine speed increases and the fluctuation rate decreases, thus completing the cold start process.

[0051] The system control procedure is as follows: First, the engine starter motor is turned on, driving the crankshaft to rotate and the piston to move. At this time, no fuel is injected into the engine cylinders; the engine is idling. Then, the ECU controller and main heating plate are turned on. If the ambient temperature is lower than the diesel fuel's condensation point, the auxiliary heating rod is also turned on. The heating plate is energized for about 1-2 minutes to raise its surface temperature sufficiently. The ECU then controls the preheating of the intake air temperature T based on the measured temperature. in Preheating the inlet air pressure P in Intake flow rate Q in Or intake air speed V in The optimal injection parameters and injection frequency f are obtained by looking up the table from the MAP chart. inj And fuel injection pulse width T inj Initiate fuel injection and flame preheating, and monitor the intake air temperature T after preheating in real time. out Preheated air-fuel ratio λ out The system determines whether suitable in-cylinder thermal conditions have been met. When the requirements are met, fuel injection and ignition begin in the engine cylinders. If the engine speed continues to rise and reaches the normal operating speed, and the speed fluctuation rate gradually decreases, then the start-up is successful and preheating stops; otherwise, preheating continues.

[0052] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of one embodiment, and the modules or processes shown in the drawings are not necessarily essential for implementing the present invention.

[0053] Those skilled in the art will understand that the modules in the apparatus of the embodiments can be distributed in the apparatus of the embodiments as described in the embodiments, or they can be located in one or more devices different from this embodiment with corresponding changes. The modules of the above embodiments can be combined into one module, or they can be further divided into multiple sub-modules.

[0054] 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 of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An intake air preheating system for cold starting a diesel engine, characterized in that, This includes an integrated upper plate, upper plate adapter plate, injector mounting bracket, injector mounting hole, injector, injector pressure plate, stud, auxiliary heating rod, auxiliary heating rod pressure block, wall temperature sensor, bracket mounting protrusion, heating plate wiring hole, heating plate bracket, spoiler, heating plate pressure plate, main heating plate, engine intake manifold, and controller. The integrated upper plate is fixed to the upper plate adapter plate, and the upper plate adapter plate is fixed to the engine intake pipe; The integrated upper plate has an injector mounting base on one side of its upper surface. The injector mounting base has an injector mounting hole. The front end of the injector is pressed into the injector mounting hole at a preset angle. The spray axis of the injector forms an acute angle with the air intake direction of the engine intake pipe. The rear end of the injector is fitted with an injector pressure plate, which is fixed to the integrated upper plate by studs. An auxiliary heating rod is inserted into the injector mounting base on the side near the front end of the injector. An auxiliary heating rod pressure block is provided on the injector mounting base at one end of the auxiliary heating rod. A wall temperature sensor is provided on the surface of the injector mounting base above the auxiliary heating rod. A slot is provided on the lower surface of the integrated upper plate on the side away from the injector. A bracket mounting protrusion is provided above the slot on the integrated upper plate. A heating plate wiring through hole is provided on the side of the integrated upper plate away from the injector. The upper plate adapter plate is a hollow plate, located below the integrated upper plate, and is fixed to the integrated upper plate with bolts; The heating plate bracket is inverted T-shaped on the front and H-shaped on the side. It is integrally formed. The upper U-shaped part is vertically inserted into the slot of the integrated upper plate. The heating plate bracket is fixed to the integrated upper plate by screwing the bolts into the bracket mounting protrusion. The middle of the heating plate bracket is provided with a baffle plate of preset height. The lower U-shaped part is reserved with horizontal holes. The lower U-shaped end of the heating plate bracket is fixed to the heating plate pressure plate by bolts. One end of the main heating plate is horizontally inserted into the pre-drilled hole at the bottom of the heating plate bracket, and the other end is located below the integrated upper plate. The heating plate bracket and the heating plate pressure plate press the main heating plate together. The wires of the main heating plate pass through the heating plate wire hole of the integrated upper plate and are connected to the AC power supply. The engine intake manifold has pre-drilled sensor mounting holes. The sensor mounting holes are located collinear with the injector mounting holes along the injector spray axis. Intake air temperature sensor, intake air pressure sensor, intake air flow sensor, and oxygen concentration sensor are installed thereto obtain intake air temperature, pressure, flow rate, or wind speed as input signals for the controller. The controller, integrated into the vehicle's electronic control unit, obtains the optimal injection frequency and injection pulse width by looking up a table based on the input signal and the pre-calibrated ignition control curve. It also performs real-time feedback control based on the intake air temperature and air-fuel ratio in the preheated engine intake manifold until the engine speed increases and the fluctuation rate decreases, thus completing the cold start process.

2. The system according to claim 1, characterized in that, The integrated upper plate and the upper plate adapter plate are sealed by a high-temperature resistant O-ring.

3. The system according to claim 1, characterized in that, The injector is a PFI injector, with the spray axis at a 45° angle to the horizontal direction and a spray pressure of 3 to 5 bar.

4. The system according to claim 1, characterized in that, The upper plate adapter is welded to the engine intake pipe.

5. The system according to claim 1, characterized in that, The main heating plate is made of high-temperature resistant silicon nitride ceramic with a rated power of 450W.

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