High-pressure air assisted engine low-temperature starting control method and device

Abstract

According to the high-pressure-air-assisted engine low-temperature starting control method and device, in the engine cold starting process, the throttle valve is closed firstly, then the pressure control valve is opened, high-pressure air is filled into the air inlet pipe, the pressure of the air inlet pipe is high, the air inlet amount in an engine cylinder can be greatly increased, and the engine low-temperature starting effect is achieved. When the piston is in the compression top dead center, the temperature is greatly increased, the cycle misfire rate of the engine is greatly reduced, the output torque of the engine is increased, the output torque is larger than the borne load, the rotating speed of the engine is rapidly increased, the target idling rotating speed is achieved, and the success rate of cold start is increased.

Description

Technical Field

[0001] This invention belongs to the field of engine low-temperature starting technology, specifically a high-pressure air-assisted engine low-temperature starting control method and device. Background Technology

[0002] Currently, existing engines are operating at low temperatures, and the lower cylinder temperatures can cause the following problems:

[0003] Poor fuel atomization: At low temperatures, the fuel evaporation rate decreases and the number of liquid fuel particles increases, making it difficult to form a uniform combustible mixture with air. This results in localized mixtures that are too rich or too lean, affecting combustion stability.

[0004] Increased ignition energy requirement: Low-temperature air-fuel mixtures have lower molecular activity and require higher ignition energy to ignite. If the spark plug has insufficient energy or carbon deposits, misfire is more likely.

[0005] Slower combustion rate: Under low temperature conditions, the chemical rate of combustion reaction decreases, the flame propagation speed slows down, and it may even extinguish midway due to excessive heat loss from the cylinder wall.

[0006] Residual exhaust gas dilution effect: During cold start, the proportion of residual exhaust gas in the cylinder is relatively high, which further dilutes the fresh air-fuel mixture and reduces its combustibility.

[0007] In summary, during a cold start of an engine, the intake pressure is low, resulting in a smaller intake volume. Consequently, the amount of air entering the engine cylinders is also less, leading to a lower piston temperature at top dead center. This lower cylinder temperature causes partial cylinder misfire, which reduces the engine's output torque. When the output torque is insufficient to overcome the load, the engine speed gradually decreases until it stops, preventing a successful start. Summary of the Invention

[0008] This invention provides a method and apparatus for controlling the low-temperature start-up of an engine with high-pressure air assistance.

[0009] To achieve the above objectives, this invention provides a low-temperature engine start control method with high-pressure air assistance. This method significantly increases the intake air volume in the engine cylinder, resulting in a substantial increase in the piston temperature at top dead center of compression. This greatly reduces the engine's cycle misfire rate, increases the engine's output torque, and ensures that the output torque exceeds the load it bears. Consequently, the engine speed rises rapidly to the target idle speed, and the start is successful.

[0010] This invention provides a low-temperature start control method for a high-pressure air-assisted engine, comprising the following steps:

[0011] S1: Compare the ambient temperature with the temperature threshold T1. If the ambient temperature > the temperature threshold T1, the engine adopts the normal start mode; if the ambient temperature ≤ the temperature threshold T1, proceed to the next step; determine whether high-pressure air assisted start is required based on the ambient temperature.

[0012] S2: Start-up status detection. If no start signal is issued, keep the high-pressure air circuit disconnected and open the throttle valve. If a start signal is issued, proceed to the next step.

[0013] S3: Compare the pressure of the high-pressure air with the pressure threshold P1. If the pressure of the high-pressure air is less than or equal to the pressure threshold P1, the high-pressure air circuit is disconnected. If the pressure of the high-pressure air is greater than the pressure threshold P1, proceed to the next step. If the pressure of the high-pressure air is too low to meet the starting conditions, it needs to be pressurized.

[0014] S4: Connect the high-pressure air passage. The throttle valve opens after a time interval t following the connection of the high-pressure air passage. This step closes the throttle valve during startup and simultaneously opens the high-pressure air passage, making the intake manifold pressure much higher than that of the existing engine. This significantly increases the intake air volume in the engine cylinders, resulting in a substantial increase in the piston temperature at top dead center of compression.

[0015] S5: Enter engine start procedure.

[0016] Preferably, the present invention further includes step S6: After successful initiation in step S5, the pressure of the high-pressure air is detected. If the pressure of the high-pressure air is greater than the pressure threshold P2, the high-pressure air is not pressurized; if the pressure of the high-pressure air is less than or equal to the pressure threshold P2, the high-pressure air is pressurized. This pressurization method ensures the pressure of the high-pressure air, resulting in stable and reliable operation.

[0017] Preferably, the present invention further includes step S6, which involves pressurizing the high-pressure air and then detecting the air pressure. If the high-pressure air pressure exceeds a third threshold P3, pressurization is stopped. This ensures that the high-pressure air pressure does not exceed the set value, thus guaranteeing stable system operation.

[0018] Preferably, in step S3 of the present invention, if the pressure of the high-pressure air is less than or equal to the pressure threshold P1, the high-pressure air is pressurized until the pressure of the high-pressure air exceeds the pressure threshold P1, at which point pressurization stops. Pressurizing the high-pressure air ensures sufficient auxiliary air pressure during cold starts, guaranteeing a smooth cold start.

[0019] Preferably, the pressure threshold P1 is 0.4 MPa, the pressure threshold P2 is 0.6 MPa, and the pressure threshold P3 is 1.0 MPa. In this invention, P1 is set to 0.6 MPa to ensure that the gas tank has sufficient pressure; otherwise, it would be unable to provide sufficient gas volume, thus guaranteeing a sufficient amount of high-pressure air and improving the start-up success rate.

[0020] Preferably, the temperature threshold T1 is -40 to -35 degrees Celsius, and the interval time t is 0.3-0.5 seconds. The T1 temperature is set between -35 and -40 degrees Celsius, which is the temperature under cold start conditions of the engine. The interval time is within 0.3-0.5 seconds. The main purpose is to prevent the pressure in the intake manifold from overshooting, which could damage the throttle valve and improve system stability.

[0021] This invention also provides a high-pressure air-assisted low-temperature engine starting device, employing the aforementioned high-pressure air-assisted low-temperature engine starting control method, comprising a high-pressure air tank, an intake pipe, a pressure control valve, a compressor, and a throttle valve; the throttle valve is disposed on the intake pipe, the high-pressure air tank is connected to the intake pipe, the pressure control valve is disposed between the high-pressure air tank and the intake pipe; the high-pressure air tank is used to store high-pressure air, the pressure control valve is used to open and close the high-pressure air passage and regulate the pressure, the compressor is connected to the high-pressure air tank and is used to pressurize the high-pressure air tank, and the throttle valve is used to control the engine intake air volume.

[0022] Preferably, the high-pressure gas tank includes a tank body; a piston chamber, which is sealed to the tank body; a piston, which is movably disposed within the piston chamber; and a spring, one end of which is connected to the piston and the other end of which is connected to the inner wall of the piston chamber. This invention employs a piston-type pressure regulating valve. In the full-gas state, the pressure and volume are the same as existing designs, i.e., the total gas storage capacity is consistent. However, with the same initial gas release, the pressure of the newly designed gas tank is maintained at a higher tank pressure due to the valve body shifting to the left under the action of the spring, compressing air. At the same remaining pressure of 0.6 MPa, the gas utilization rate is higher.

[0023] Preferably, the diameter of the piston chamber is larger than the diameter of the tank body, and a variable cross-section tank body is used, which can increase the pressure by a greater margin and improve gas utilization under the same valve body displacement.

[0024] In this invention, the high-pressure air tank is used to store high-pressure air, which is provided by another set of equipment; the filter is used to ensure that the air is clean; the pressure control valve is used to regulate the pressure in the intake manifold; the throttle valve is used to keep it closed during startup, making the intake manifold a closed space, so that a high pressure can be maintained when the high-pressure air tank releases pressure.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] This invention closes the throttle valve during startup while opening the pressure control valve, making the intake manifold pressure much higher than in the old design. As a result, the intake air volume in the engine cylinders increases significantly, and the temperature of the piston at the top dead center of the compression stroke increases dramatically. This greatly reduces the engine's cycle misfire rate, increases the engine's output torque, and makes the output torque greater than the load it bears. The engine speed rises rapidly to reach the target idle speed, and the startup is successful.

[0027] The pressure and volume are the same as the old design when the gas is full, meaning the total gas storage capacity is the same. However, with the same initial gas release capacity, the pressure of the new gas storage tank is maintained at a higher tank pressure due to the valve body moving to the left under the action of the spring, compressing the air. When the remaining pressure is 0.6 MPa, the gas utilization rate is higher.

[0028] By using a variable cross-section tank, that is, the diameter of the piston chamber is larger than the diameter of the tank, the pressure increase can be greater and the gas utilization rate can be higher under the same valve body displacement. Attached Figure Description

[0029] Figure 1 This is a control flowchart of a high-pressure air-assisted engine low-temperature start control method according to the present invention.

[0030] Figure 2 This is a control logic block diagram of a high-pressure air-assisted engine low-temperature start control method according to the present invention.

[0031] Figure 3 This is a schematic diagram of the structure of a high-pressure air-assisted engine low-temperature starting device according to the present invention.

[0032] Figure 4 This is a schematic diagram of the high-pressure gas tank described in this invention.

[0033] In the diagram: 1-High-pressure gas tank, 101-Tank body, 102-Piston chamber, 103-Piston, 104-Spring, 105-Gas inlet, 2-Inlet pipe, 3-Pressure control valve, 4-Compressor, 5-Throttle valve. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0035] Example 1:

[0036] like Figure 1 and Figure 2 As shown, a low-temperature start control method for a high-pressure air-assisted engine includes the following steps:

[0037] S1: Compare the ambient temperature with the temperature threshold T1. If the ambient temperature > the temperature threshold T1, the engine will start in the normal mode. If the ambient temperature ≤ the temperature threshold T1, proceed to the next step.

[0038] S2: Start-up status detection. If no start signal is issued, keep the high-pressure air circuit disconnected and open the throttle valve. If a start signal is issued, proceed to the next step.

[0039] S3: Compare the pressure of the high-pressure air with the pressure threshold P1. If the pressure of the high-pressure air is less than or equal to the pressure threshold P1, the high-pressure air path is disconnected. If the pressure of the high-pressure air is greater than the pressure threshold P1, proceed to the next step.

[0040] S4: Connect the high-pressure air passage. The throttle valve opens after a time interval t following the connection of the high-pressure air passage.

[0041] S5: Enter engine start procedure.

[0042] In this embodiment, step S6 is also included: after successful startup, the pressure of the high-pressure air is detected. If the pressure of the high-pressure air is greater than the pressure threshold P2, the high-pressure air is not pressurized; if the pressure of the high-pressure air is less than or equal to the pressure threshold P2, the high-pressure air is pressurized. The pressurization method ensures the pressure of the high-pressure air, making the operation stable and reliable.

[0043] In this embodiment, the invention further includes step S6, which involves pressurizing the high-pressure air and then detecting its pressure. If the high-pressure air pressure exceeds a third threshold P3, pressurization is stopped. This ensures that the high-pressure air pressure does not exceed the set value, guaranteeing stable system operation.

[0044] In this embodiment, in step S3 of the present invention, if the pressure of the high-pressure air is less than or equal to the pressure threshold P1, the high-pressure air is pressurized until the pressure of the high-pressure air exceeds the pressure threshold P1, at which point pressurization stops. Pressurizing the high-pressure air ensures sufficient auxiliary air pressure during cold starts, guaranteeing a smooth cold start.

[0045] In this embodiment, the pressure threshold P1 is 0.4 MPa, the pressure threshold P2 is 0.6 MPa, and the pressure threshold P3 is 1.0 MPa.

[0046] In this embodiment, the temperature threshold T1 is -40 degrees Celsius, and the interval time t is 0.3 seconds.

[0047] Example 2:

[0048] like Figure 3As shown, this embodiment 2 is a low-temperature engine starting device assisted by high-pressure air using the method described in embodiment 1 above. It includes a high-pressure air tank 1, an intake pipe 2, a pressure control valve 3, a compressor 4, and a throttle valve 5. The throttle valve 5 is installed on the intake pipe 2. The high-pressure air tank 1 and the intake pipe 2 are connected. The pressure control valve 3 is installed between the high-pressure air tank 1 and the intake pipe 2. The high-pressure air tank 1 is used to store high-pressure air. The pressure control valve 3 is used to open and close the high-pressure air passage and adjust the pressure. The compressor 4 is connected to the high-pressure air tank 1 and is used to pressurize the high-pressure air tank 1. The throttle valve 5 is used to control the engine intake air volume.

[0049] like Figure 4 As shown, in this embodiment, the high-pressure gas tank 1 includes a tank body 101; a piston chamber 102, which is sealed to the tank body 101; a piston 103, which is movably disposed within the piston chamber 102; and a spring 104, one end of which is connected to the piston 103 and the other end of which is connected to the inner wall of the piston chamber 102. The diameter of the piston chamber 102 is larger than the diameter of the tank body 101. In this embodiment, the movable valve plate is named piston 103. Piston 103 moves left and right within the piston chamber 102. When the gas tank pressure is atmospheric pressure, piston 103 is pushed to a certain position on the far left of piston chamber 102 by spring 104. As compressor 4 pressurizes the high-pressure gas tank 1 to a certain pressure, piston 103 begins to move to the right. As the pressure rises to a certain level, piston 103 is compressed to a certain position on the far right.

[0050] like Figure 4 As shown, in this embodiment, there is one piston chamber 102, which is located on the right side of the tank body 101.

[0051] This embodiment also includes an air inlet 105, which is located on the outer wall of the piston chamber 102 and is used to connect the piston chamber 102 with the atmosphere.

[0052] In this embodiment, the left end of the spring 104 can be welded or the piston 103 can be designed as a structure with a tube on the right side. The inner diameter of the tube is clearance-fitted with the outer diameter of the spring 104. The spring 104 is inserted into the tube for positioning. A single spring 104 or multiple springs 104 can be designed according to the requirements. The right end of the spring 104 can be designed as fixed or free according to the requirements.

[0053] In this embodiment, the temperature threshold T1 is -35 degrees Celsius, and the interval time t is 0.5 seconds.

Claims

1. A high-pressure air-assisted engine cold-start control method, characterized by The method comprises the following steps: S1: comparing the ambient temperature with a temperature threshold T1, if the ambient temperature > the temperature threshold T1, the engine adopts a normal starting mode; if the ambient temperature ≤ the temperature threshold T1, the next step is entered; S2: starting state detection, if no starting signal is sent, the high-pressure air path is kept disconnected and the throttle valve is opened, if the starting signal is sent, the next step is entered; S3: comparing the pressure of the high-pressure air with a pressure threshold P1, if the pressure of the high-pressure air ≤ the pressure threshold P1, the high-pressure air path is disconnected; if the pressure of the high-pressure air > the pressure threshold P1, the next step is entered; S4: connecting the high-pressure air path, the throttle valve is opened after the high-pressure air path is connected for an interval time t; S5: entering the engine starting program.

2. A high pressure air assisted engine cold start control method according to claim 1, characterised in that Further comprising step S6: after the starting is successful, detecting the pressure of the high-pressure air, if the pressure of the high-pressure air > a pressure threshold P2, the high-pressure air is not pressurized; if the pressure of the high-pressure air ≤ the pressure threshold P2, the high-pressure air is pressurized.

3. A high pressure air assisted engine cold start control method according to claim 1, characterized in that Further comprising that in step S6, after the high-pressure air is pressurized, the pressure of the high-pressure air is detected, if the pressure of the high-pressure air > a third threshold P3, the pressurization is stopped.

4. A high pressure air assisted engine cold start control method according to claim 1, characterized in that In step S3, if the pressure of the high-pressure air ≤ the pressure threshold P1, the high-pressure air is pressurized until the pressure of the high-pressure air > the pressure threshold P1, the pressurization is stopped.

5. A high pressure air assisted engine cold start control method according to claim 1, characterized in that The pressure threshold P1 is 0.4 Mpa, the pressure threshold P2 is 0.6 Mpa, and the pressure threshold P3 is 1.0 Mpa.

6. A high pressure air assisted engine cold start control method according to claim 1, characterized in that The temperature threshold T1 is -40~ -35 degrees Celsius, and the interval time t is 0.3-0.5 seconds.

7. A high pressure air assisted engine cold start device characterised in that The high-pressure air assisted engine low-temperature starting control method according to any one of the preceding claims comprises a high-pressure air tank (1), an air inlet pipe (2), a pressure control valve (3), a compressor (4), and a throttle valve (5); the throttle valve (5) is arranged on the air inlet pipe (2), the high-pressure air tank (1) is connected with the air inlet pipe (2), and the pressure control valve (3) is arranged between the high-pressure air tank (1) and the air inlet pipe (2); the high-pressure air tank (1) is used for storing high-pressure air, the pressure control valve (3) is used for controlling the opening and closing of the high-pressure air path and adjusting the pressure, the compressor (4) is connected with the high-pressure air tank (1) and is used for pressurizing the high-pressure air tank (1), and the throttle valve (5) is used for controlling the engine air intake.

8. A high pressure air assisted engine cold start device as claimed in claim 6, wherein The high-pressure air tank (1) comprises a tank body (101), a piston cavity (102) which is sealingly connected with the tank body (101), and a piston (103) which is movably arranged in the piston cavity (102); a spring (104) is connected with one end of the piston (103) and the inner wall surface of the piston cavity (102).

9. A high pressure air assisted engine cold start device as claimed in claim 6, wherein: The diameter of the piston cavity (102) is greater than the diameter of the tank body (101).

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