Electric drive oil-gas separator control method combining pilot index and direct index

Abstract

The invention discloses an electric-driven oil-gas separator control method combining a leading indicator with a direct indicator, comprising a variable frequency motor operating frequency control method; when P0≤‑1.5 kPa or P0≥‑0.5 kPa, the variable frequency motor operating frequency control method is started, and a basic data acquisition method is continuously operated; the variable frequency motor operating frequency control method is: an on-board ECU acquires the current engine speed S0 once every 10 seconds, and calculates ⊿H=∣{(S0-SD) / SD}×H0∣; when 0≥P0≥‑0.5 kPa, the on-board ECU adjusts the operating frequency of the variable frequency motor to a target value, and the target value is the smaller value between (H0+⊿H) and MAX; when -2≤P0≤‑1.5 kPa, the on-board ECU adjusts the operating frequency of the variable frequency motor to a target value, and the target value is the larger value between (H0-⊿H) and MIN. The present invention takes into account both direct indicators and leading indicators, and the pressure change in the crankcase is more gradual, and the pressure in the crankcase can be more stabilized near the optimal value.

Description

Technical Field

[0001] The invention relates to the technical field of natural gas motor vehicles, and in particular to a crankcase blowby gas pressure control technology. Background Art

[0002] During the operation of the internal combustion engine, blowby gas is generated, which increases the pressure in the crankcase. If the blowby gas is not discharged in time in the crankcase, the crankcase pressure will increase. In severe cases, it will cause crankcase leakage, affecting the normal operation of the internal combustion engine.

[0003] Blow-by gas contains impurities such as engine oil, carbon black and colloid. If it is directly discharged into the atmosphere, it will cause air pollution and fail to meet national emission regulations. In addition, the direct discharge of blow-by gas will cause the loss of engine oil in the internal combustion engine, resulting in increased oil consumption and, in severe cases, poor lubrication of the internal combustion engine.

[0004] The electrically driven oil-gas separator developed by the applicant can effectively filter impurities in the blowby gas and meet the national VI b stage emission requirements.

[0005] The pressure in the crankcase fluctuates. For gas commercial vehicles, the pressure in the crankcase is required to be greater than or equal to -2 kPa and less than or equal to 0 kPa.

[0006] If the motor speed of the electric oil-gas separator remains unchanged, the pressure in the crankcase cannot be stabilized in the above range. Therefore, it is necessary to design a motor adjustment method for the electric oil-gas separator. When the crankcase pressure is too high, the motor speed of the electric oil-gas separator is increased, thereby accelerating the processing and discharge of blowby gas in the crankcase and reducing the crankcase pressure; at the same time, when the crankcase pressure is too low, the motor speed of the electric oil-gas separator is reduced, thereby reducing the speed of processing and discharging blowby gas in the crankcase and increasing the crankcase pressure.

[0007] The usual control idea is result-oriented, that is, measures are taken to reduce the pressure when the crankcase pressure is too high, and measures are taken to increase the pressure when the crankcase pressure is too low. Specifically, the motor of the electric-driven oil-gas separator can be made of a variable frequency motor, and a pressure sensor is set in the crankcase. Controlling the speed of the motor according to the signal of the pressure sensor helps to achieve the goal of controlling the pressure in the crankcase. However, the applicant has found through experiments that under this control method, the crankcase pressure fluctuation may still be large and not stable enough.

[0008] The reason for this is that passive tracking and adjusting the pressure value (control target) in the crankcase must be carried out after the control target has changed significantly, and passive regulation will inevitably have large fluctuations.

[0009] The inventor's research idea is to not only conduct result-oriented regulation, but also cause-oriented regulation.

[0010] The applicant's research shows that the source of the increased pressure in the crankcase is a small amount of gas leakage at the piston ring of the engine piston, which forms high-pressure blowby gas. The high-pressure blowby gas enters the crankcase and increases the pressure in the crankcase. When the motor speed of the electric-driven oil-gas separator remains unchanged, the higher the engine speed, the more frequent the piston movement, the larger (faster) the blowby gas volume (speed), and the higher the pressure in the crankcase. Conversely, the pressure in the crankcase will increase.

[0011] Based on the above principles, the basic idea of ​​the research and development of the present invention is: the direct indicator (pressure in the crankcase) is combined with the pilot indicator (engine speed), and the control start conditions are set. After the control start conditions are met, when the pilot indicator changes, without waiting for the process of the pilot indicator to be converted into the direct indicator, in the process of the pilot indicator causing the direct indicator to change (instead of waiting until the direct indicator changes to a certain extent), the motor operating frequency is synchronously reversed (the higher the operating frequency of the variable frequency motor, the higher its speed), and the change of the direct indicator is reversely adjusted, so that the pressure change in the crankcase is smoother and the pressure in the crankcase is more stable. Summary of the invention

[0012] The purpose of the present invention is to provide an electric-driven oil-gas separator control method combining a pilot indicator with a direct indicator, implement the above-mentioned basic research and development ideas, make the pressure change in the crankcase of a natural gas vehicle more gradual, and the pressure in the crankcase can be more stabilized near the optimal value.

[0013] To achieve the above object, the present invention provides an electric-driven oil-gas separator control method combining a pilot indicator with a direct indicator, wherein the electric-driven oil-gas separator has a variable frequency motor, a pressure sensor is provided in the crankcase of a motor vehicle, and the variable frequency motor and the pressure sensor are respectively connected to the vehicle-mounted ECU through the vehicle-mounted circuit; after the engine is started, a basic data acquisition method and a variable frequency motor operating frequency control method based on the basic data are performed;

[0014] The maximum operating frequency of the variable frequency motor is defined as MAX, and the minimum operating frequency of the variable frequency motor is defined as MIN;

[0015] When the engine is initially started, the vehicle ECU controls the operating frequency of the variable frequency motor to (MAX+MIN) / 2;

[0016] 1. The basic data acquisition method is:

[0017] ① The on-board ECU collects the crankcase pressure data through the pressure sensor once a second to obtain the current pressure value P0; -1.05 kPa ≤ P0 ≤ -0.95 kPa is the optimal crankcase pressure range;

[0018] ② Each time the P0 value is collected, if P0 is in the optimal crankcase pressure range, the on-board ECU records the engine speed S1 when the optimal pressure occurs;

[0019] ③ When the number of S1 is greater than or equal to 10, the on-board ECU takes the average of the last 10 S1 values ​​as the recent optimal engine speed SJ; defines the optimal engine speed SD for calculation, and before the first calculation of SJ, the current S1 value is used as the value of SD; after the first calculation of SJ, the current SJ value is used as the value of SD;

[0020] ④ The on-board ECU collects the current operating frequency H0 of the variable frequency motor once a second;

[0021] 2. When P0≤-1.5 kPa or P0≥-0.5 kPa, the variable frequency motor operating frequency control method is started, and the basic data acquisition method is continuously operated;

[0022] The frequency control method of variable frequency motor is:

[0023] The on-board ECU obtains the current engine speed S0 every 10 seconds and calculates ⊿H=|{(S0-SD) / SD}×H0|;

[0024] When P0>0, the on-board ECU adjusts the operating frequency of the variable frequency motor to MAX;

[0025] When P0 < -2 kPa, the on-board ECU adjusts the operating frequency of the variable frequency motor to MIN;

[0026] When 0 ≥ P0 ≥ -0.5 kPa, the on-board ECU adjusts the operating frequency of the variable frequency motor to the target value, which is the smaller value between (H0 + ⊿H) and MAX;

[0027] When -2≤P0≤-1.5 kPa, the on-board ECU adjusts the operating frequency of the variable frequency motor to the target value, which is the larger value between (H0-⊿H) and MIN.

[0028] In the variable frequency motor operating frequency control method, when 0≥P0≥-0.5 kPa and ⊿H≤0.1 H0, the operating frequency of the variable frequency motor is directly adjusted to the corresponding target value; when 0≥P0≥-0.5 kPa and ⊿H>0.1 H0, the operating frequency of the variable frequency motor is gradually increased at a speed of 0.1 H0 / second until the operating frequency of the variable frequency motor is adjusted to the corresponding target value;

[0029] When -2≤P0≤-1.5 kPa and ⊿H≤0.1 H0, directly adjust the operating frequency of the variable frequency motor to the corresponding target value; when -2≤P0≤-1.5 kPa and ⊿H>0.1 H0, gradually increase the operating frequency of the variable frequency motor at a speed of 0.1 H0 / s until the operating frequency of the variable frequency motor is adjusted to the corresponding target value.

[0030] The electric-driven oil-gas separator comprises a shell, an air inlet is arranged at the upper part of the shell, the air inlet is used to connect to the upper part of the crankcase, an air outlet is arranged at the lower part of the other side of the shell, the air outlet is used to discharge the filtered gas; a partition structure is arranged at the middle part of the shell, the partition structure and the shell above it form an air inlet cavity, and the partition structure and the shell below it form an air outlet cavity; a vent is arranged at the middle part of the partition structure;

[0031] An air pump is provided in the air inlet cavity corresponding to the air inlet, the air pump is connected upwardly to the variable frequency motor, the circumferential end surface of the air pump shell is open and used to inhale gas; a plurality of blades for inhaling air during rotation are provided in the air pump shell, the air pump shell is connected downwardly to an air outlet pipe, and the air outlet pipe extends downwardly into the air vent; the partition structure is connected downwardly to a vent cylinder, the vent cylinder encloses the vent and its bottom end is closed; a plurality of air vents are provided on the circumferential side wall of the vent cylinder, a filter cartridge made of filter material is provided on the outer cover of the vent cylinder, a cover cylinder is attached to the circumferential outer wall of the filter cartridge, and the cover cylinder is connected upwardly to the partition structure;

[0032] A baffle cylinder is arranged upward at the bottom of the shell, the lower end of which is connected to the bottom surface of the shell, the top of which encloses the bottom of the cover cylinder and the filter cylinder, and a connecting port is formed at the top of the baffle cylinder outside the cover cylinder; the shell inside the baffle cylinder is downwardly connected to an oil return port, which is used to connect to the oil pan of the crankcase;

[0033] The bottom of the shell is in a cone shape with a larger top and a smaller bottom, and the oil return port is arranged at the bottom of the shell cone; a rotating sealing structure is arranged between the vent and the outlet pipe; an oil seepage film is arranged in the baffle cylinder directly below the filter cylinder, and the oil seepage film is higher than the oil return port.

[0034] The present invention has the following advantages:

[0035] 1. The change of the leading indicator precedes the change of the direct indicator. The present invention adjusts the frequency conversion amplitude according to the change degree of the leading indicator. Compared with the regulation according to the direct indicator, it has a certain pre-regulation ability, that is, while the leading indicator causes the crankcase pressure to increase or decrease, the control method of the present invention causes the crankcase pressure to change in the opposite direction (decreasing or increasing), which can make the pressure change in the crankcase more stable and stabilize near the optimal value for a longer time.

[0036] 2. During the operation of the motor vehicle, the recent optimal engine speed SJ is continuously calculated. Since the driving conditions of the motor vehicle (road conditions, average speed, etc.) may remain relatively stable for a long period of time (the conditions on urban roads and highways are obviously different, but the driving conditions at various places on highways are generally similar, and the driving conditions at various places on urban roads are generally similar), using SJ as a reference for regulation can make the regulation result more consistent with the recent driving conditions of the motor vehicle when the driving environment has not changed significantly. After the driving environment of the motor vehicle has changed significantly (such as from urban roads to highways), after collecting S1 10 times, SJ can gradually match the new driving environment in this process, thereby continuing to maintain the advantage of making the regulation result more consistent with the recent driving conditions of the motor vehicle.

[0037] 3. The present invention takes into account the direct index (crankcase pressure P0), reduces the operating frequency of the variable frequency motor when P0≤-1.5 kPa, and increases the operating frequency of the variable frequency motor when P0≥-0.5 kPa, so as to make the P0 value return to the optimal value, i.e. -1.

[0038] The present invention also takes into account a leading indicator (i.e., engine speed), which includes a matching characteristic for the recent driving condition of the motor vehicle (recent optimal engine speed SJ). The greater the deviation between the current engine speed and the recent optimal engine speed SJ, the greater the amplitude of the variable frequency regulation, so that the control action is more closely matched with the recent operating condition of the motor vehicle, and the crankcase pressure is steadily returned to around -1 kPa. Except in extreme cases (such as when the variable frequency motor runs at the MAX frequency, it cannot prevent the crankcase pressure from being higher than 0, or when the variable frequency motor runs at the MIN frequency, it cannot prevent the crankcase pressure from being lower than -2), compared with not considering the leading indicator, the crankcase pressure can be maintained near the optimal value of -1 for a longer time.

[0039] The present invention is more effective when used in autonomous driving because: the control behavior in autonomous driving is usually softer and more stable than that in manual driving. The more stable the recent driving and operating conditions of the motor vehicle, including the control conditions, are, the more SJ matches the actual conditions.

[0040] 4. When adjusting the speed of the variable frequency motor, control the adjustment speed to less than or equal to 0.1 H0 / second, so as to ensure the stability of the adjustment process and avoid the variable frequency motor from adjusting the operating frequency too quickly when the engine speed increases rapidly (such as when the motor vehicle starts and the driver steps on the accelerator, the engine speed may increase from 600rpm at idle to more than 1200rpm; when the accelerator is deeply stepped on, it may increase to more than 3000rpm). Slowly adjusting the speed of the variable frequency motor is not only more energy-saving, but also smoother, which increases the overall service life of the variable frequency motor and the electric drive oil-gas separator.

[0041] 5. During operation, the airflow outside the blades hits the inner wall of the air intake cavity during rotation, and some particles hit the inner wall and then leave the airflow, forming the first particle separation (filtration) effect; when the blades drive the airflow to move at high speed, the particles in the airflow hit each other and gather, forming the second particle separation effect; when the airflow passes through the filter material of the filter cartridge, the particles are blocked in the filter material, forming the third particle separation effect. The present invention improves the effect of particle separation and filtration through multi-stage particle separation; the oil in the gas does not move upward with the return airflow under the action of gravity, realizing oil-gas separation, efficiently separating the oil, particles and gas in the crankcase blowby gas, discharging the filtered gas, ensuring that the emission meets the standard, and allowing the engine oil to flow back into the crankcase.

[0042] 6. The oil return port is the lowest, which is convenient for the separated oil to be concentrated and then returned to the oil pan of the crankcase. The rotary seal structure can prevent the downward airflow from flowing back out of the intake cavity through the gap between the vent and the outlet pipe, thereby improving the effect of flow and oil-gas separation.

[0043] 7. The oil seepage film blocks the downward airflow and makes the airflow return upward. The oil that hits the oil seepage film adheres to the oil seepage film, gradually penetrates downward and flows to the oil return port, and then the engine oil flows back into the crankcase oil pan. The oil seepage film can greatly reduce the gas that flows back into the crankcase from the oil return port, and improve the effect of oil-gas separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the structure of an electrically driven oil-gas separator;

[0045] Figure 2 It is a schematic diagram of the cross-sectional structure of an electrically driven oil-gas separator. Figure 2 The arrow in the middle indicates the airflow direction. DETAILED DESCRIPTION

[0046] like Figure 1 to Figure 2 As shown, the electrically driven oil-gas separator of the present invention comprises a housing, an air inlet 2 is provided at the upper part of the housing, the air inlet 2 is used to connect to the upper part of the crankcase, and an air outlet 3 is provided at the lower part of the other side of the housing, the air outlet 3 is used to discharge the filtered gas; the engine and crankcase of the motor vehicle are conventional technologies, not shown in the figure. The housing comprises an upper housing 4 and a lower housing 5 connected together by a flange structure 1.

[0047] A partition structure 6 is provided in the middle of the shell. The partition structure 6 and the shell above it form an air inlet cavity 7, and the partition structure 6 and the shell below it form an air outlet cavity 8. A vent 9 is provided in the middle of the partition structure 6.

[0048] An air pump is provided in the air inlet cavity 7 corresponding to the air inlet 2, and the air pump is upwardly connected to a variable frequency motor 10, specifically, the air pump shell is upwardly connected to the output shaft of the variable frequency motor 10; the circumferential end surface of the air pump shell 11 is open and used to inhale gas; a plurality of blades 12 for inhaling air during rotation are provided around the central axis of the air pump in the air pump shell 11, and an air outlet pipe 13 is downwardly connected to the air pump shell 11, and the air outlet pipe 13 extends downward into the air vent 9; the partition structure 6 is downwardly connected to a ventilation cylinder 14, and the ventilation cylinder 14 encloses the air vent 9 and its bottom end is closed; a plurality of air vents 15 are provided on the circumferential side wall of the ventilation cylinder 14, and a filter cartridge 16 made of a filter material (such as filter paper) is provided on the outer diameter cover of the ventilation cylinder 14, and a cover cylinder 17 is attached to the circumferential outer wall of the filter cartridge 16, and the cover cylinder 17 is upwardly connected to the partition structure 6;

[0049] A baffle cylinder 18 is provided upward at the bottom end of the lower shell body 5, and the lower end of the baffle cylinder 18 is connected to the bottom surface of the lower shell body 5. The top of the baffle cylinder 18 encloses the bottom of the cover cylinder 17 and the filter cylinder 16, and a connecting port 19 is formed at the top of the baffle cylinder outside the cover cylinder 17; the connecting port 19 connects the baffle cylinder 18 with the air outlet cavity 8.

[0050] The housing in the baffle cylinder 18 is connected downwardly with an oil return port 20, which is used to communicate with the oil pan of the crankcase (of the engine of the motor vehicle). The oil pan is an inherent part of the crankcase and is not shown in the figure.

[0051] During operation, the airflow outside the blade 12 hits the inner wall of the air intake chamber 7 during rotation, and some particles hit the inner wall and then leave the airflow, forming the first particle separation (filtration) effect; in the process of the blade 12 driving the airflow to move at high speed, the particles in the airflow hit each other and gather, forming the second particle separation effect; when the airflow passes through the filter material of the filter cartridge 16, the particles are blocked in the filter material, forming the third particle separation effect. The present invention improves the effect of particle separation and filtration through multi-stage particle separation; the oil in the gas does not move upward with the return airflow under the action of gravity and inertia, realizing oil-gas separation, efficiently separating the oil, particles and gas in the crankcase blowby gas, discharging the filtered gas, ensuring that the emission meets the standard, and allowing the engine oil to flow back into the crankcase.

[0052] The bottom of the lower housing 5 is in a tapered shape with a large top and a small bottom, and the oil return port 20 is arranged at the bottom of the tapered part of the lower housing. The oil return port 20 is the lowest, which is convenient for the separated engine oil to be concentrated and then flow back into the crankcase.

[0053] A rotary seal structure is provided between the vent 9 and the outlet pipe 13. The rotary seal structure can be a sliding ring made of filled polytetrafluoroethylene and a rubber O-ring providing elasticity, which is a conventional technology and will not be described in detail. Other forms of rotary seal structures can also be used. The rotary seal structure can prevent the downward airflow from flowing back upward out of the air inlet cavity 7 through the gap between the vent 9 and the outlet pipe 13, thereby improving the effect of flow and oil-gas separation.

[0054] An oil permeable membrane 21 is provided in the deflector 18 directly below the filter cartridge 16, and the oil permeable membrane 21 is higher than the oil return port 20. The oil permeable membrane 21 blocks the downward airflow and makes the airflow return upward. The oil that hits the oil permeable membrane 21 adheres to the oil permeable membrane 21, gradually penetrates downward and flows to the oil return port 20, thereby causing the engine oil to flow back into the crankcase oil pan. The oil permeable membrane 21 can greatly reduce the gas that flows back into the crankcase from the oil return port 20, thereby improving the oil-gas separation effect.

[0055] During operation, the vehicle-mounted ECU controls the variable frequency motor 10, which drives the air pump to rotate. The blades 12 of the air pump inhale the gas in the air inlet chamber 7 (from the crankcase of the motor vehicle engine) during rotation and send it downward to the breather 14 through the outlet pipe 13 at high speed. Since the inner end of the breather 14 is closed, the oil-containing gas enters the filter cartridge 16 along the air vent 15. Since the filter cartridge 16 is covered in the cover cylinder 17, the oil-containing gas passes through the filter cartridge 16 downward and enters the baffle cylinder 18, and then baffles upward in the baffle cylinder 18 and enters the air outlet chamber 8. Finally, the filtered gas is discharged into the environment through the outlet 3. During operation, the blades 12 generate a rotating airflow in the air inlet chamber 7 outside the air pump when rotating. The large impurities in the gas hit the inner wall of the shell during rotation and leave the airflow, realizing the first separation of impurity particles. When the gas inhaled by the air pump rotates at high speed in the air pump, the particles in it collide with each other, and the small particles gather into large particles, so that the blowby gas is separated twice in a limited space. After the gas enters the vent cylinder 14 at high speed from the outlet pipe 13, it flows into the filter cartridge 16 through the vent hole on the side wall of the vent cylinder 14. When passing through the filter cartridge 16, it is filtered by the filter material of the filter cartridge 16, and the particles are blocked by the filter cartridge 16, forming a third particle separation effect. The three-level separation makes the particle filtering effect in the gas very high, and improves the cleanliness of the exhaust gas. When the oil-containing gas moves downward through the filter material of the filter cartridge 16, the airflow that hits the oil seepage film 21 is turned back upward, and the oil that hits the oil seepage film 21 adheres to the oil seepage film 21, gradually penetrates downward and flows to the oil return port 20.

[0056] The electric-driven oil-gas separator control method combining the pilot indicator with the direct indicator of the present invention is aimed at the above-mentioned electric-driven oil-gas separator, and a pressure sensor is provided in the crankcase of the motor vehicle. The variable frequency motor 10 and the pressure sensor are respectively connected to the vehicle-mounted ECU through the vehicle-mounted circuit; The vehicle-mounted ECU obtains the engine speed in a conventional technology, which will not be described in detail. After the engine is started, the basic data acquisition method and the variable frequency motor operating frequency control method based on the basic data are performed;

[0057] The maximum operating frequency of the variable frequency motor 10 is defined as MAX, and the minimum operating frequency of the variable frequency motor 10 is defined as MIN. In the present invention, the unit of the operating frequency of the variable frequency motor 10 is always Hertz.

[0058] When the engine is initially started, the vehicle-mounted ECU controls the operating frequency of the variable frequency motor 10 to be (MAX+MIN) / 2;

[0059] 1. The basic data acquisition method is:

[0060] ① The vehicle-mounted ECU collects the pressure data in the crankcase through the pressure sensor once a second to obtain the current pressure value P0. In the present invention, the unit of the crankcase pressure is always kPa; -1.05 kPa ≤ P0 ≤ -0.95 kPa is the optimal crankcase pressure range;

[0061] ② Each time the P0 value is collected, if P0 is in the optimal crankcase pressure range, the on-board ECU records the engine speed S1 when the optimal pressure occurs this time; in the present invention, the unit of all engine speeds involved is rpm, i.e., revolutions per minute.

[0062] ③ When the number of S1 is greater than or equal to 10, the on-board ECU takes the average of the last 10 S1 values ​​as the recent optimal engine speed SJ; defines the optimal engine speed SD for calculation, and before the first calculation of SJ, the current S1 value is used as the value of SD; after the first calculation of SJ, the current SJ value is used as the value of SD;

[0063] ④ The vehicle-mounted ECU collects the current operating frequency H0 of the variable frequency motor 10 once per second;

[0064] 2. When P0≤-1.5 kPa or P0≥-0.5 kPa, the variable frequency motor operating frequency control method is started, and the basic data acquisition method is continuously operated;

[0065] The frequency control method of the variable frequency motor is performed once every 10 seconds, specifically:

[0066] The on-board ECU obtains the current engine speed S0 every 10 seconds and calculates ⊿H = |{(S0-SD) / SD}×H0| (i.e., the absolute value of (S0-SD) / SD}×H0);

[0067] When P0>0, the vehicle-mounted ECU adjusts the operating frequency of the variable frequency motor 10 to MAX;

[0068] When P0 < -2 kPa, the on-board ECU adjusts the operating frequency of the variable frequency motor to MIN;

[0069] When 0 ≥ P0 ≥ -0.5 kPa, the on-board ECU adjusts the operating frequency of the variable frequency motor 10 to a target value, which is the smaller value between (H0 + ⊿H) and MAX;

[0070] When -2≤P0≤-1.5 kPa, the on-board ECU adjusts the operating frequency of the variable frequency motor 10 to a target value, which is the larger value between (H0-⊿H) and MIN.

[0071] The electric drive oil-gas separator control method combining the pilot indicator with the direct indicator of the present invention has the following advantages:

[0072] 1. During the operation of the motor vehicle, the recent optimal engine speed SJ is continuously calculated. Since the driving conditions of the motor vehicle (road conditions, average speed, etc.) may remain relatively stable for a long period of time (the conditions on urban roads and highways are obviously different, but the driving conditions at various places on highways are generally similar, and the driving conditions at various places on urban roads are generally similar), using SJ as a reference for regulation can make the regulation result more consistent with the recent driving conditions of the motor vehicle when the driving environment has not changed significantly. After the driving environment of the motor vehicle has changed significantly (such as from urban roads to highways), after collecting S1 10 times, SJ can gradually match the new driving environment in this process, thereby continuing to maintain the advantage of making the regulation result more consistent with the recent driving conditions of the motor vehicle.

[0073] 2. The present invention takes into account the direct index (crankcase pressure P0), reduces the operating frequency of the variable frequency motor 10 when P0≤-1.5 kPa, and increases the operating frequency of the variable frequency motor 10 when P0≥-0.5 kPa, so as to make the P0 value return to the optimal value, i.e. -1.

[0074] The present invention also takes into account a leading indicator (i.e., engine speed), which includes a matching characteristic for the recent driving condition of the motor vehicle (recent optimal engine speed SJ). The greater the deviation between the current engine speed and the recent optimal engine speed SJ, the greater the amplitude of the frequency conversion adjustment, so that the control action is more closely matched with the recent operating condition of the motor vehicle, and the crankcase pressure returns steadily to around -1 kPa. Except in extreme cases (such as when the variable frequency motor 10 runs at the MAX frequency, it cannot prevent the crankcase pressure from being higher than 0, or when the variable frequency motor 10 runs at the MIN frequency, it cannot prevent the crankcase pressure from being lower than -2), compared with not considering the leading indicator, the crankcase pressure can be kept near the optimal value of -1 for a longer time.

[0075] The present invention is more effective when used in autonomous driving because: the control behavior in autonomous driving is usually softer and more stable than that in manual driving. The more stable the recent driving and operating conditions of the motor vehicle, including the control conditions, are, the more SJ matches the actual conditions.

[0076] In the variable frequency motor operating frequency control method, when 0≥P0≥-0.5 kPa and ⊿H≤0.1 H0, the operating frequency of the variable frequency motor 10 is directly adjusted to the corresponding target value; when 0≥P0≥-0.5 kPa and ⊿H>0.1 H0, the operating frequency of the variable frequency motor 10 is gradually increased at a speed of 0.1 H0 / second until the operating frequency of the variable frequency motor 10 is adjusted to the corresponding target value;

[0077] When -2≤P0≤-1.5 kPa and ⊿H≤0.1 H0, the operating frequency of the variable frequency motor 10 is directly adjusted to the corresponding target value; when -2≤P0≤-1.5 kPa and ⊿H>0.1 H0, the operating frequency of the variable frequency motor 10 is gradually increased at a speed of 0.1 H0 / s until the operating frequency of the variable frequency motor 10 is adjusted to the corresponding target value.

[0078] When adjusting the speed of the variable frequency motor 10, the adjustment speed is controlled to be less than or equal to 0.1 H0 / second, so as to ensure the stability of the adjustment process and avoid the variable frequency motor 10 from adjusting the operating frequency too fast when the engine speed increases rapidly (for example, when the motor vehicle starts and the driver steps on the accelerator, the engine speed may increase from 600rpm at idle to more than 1200rpm; when the accelerator is deeply stepped on, it may increase to more than 3000rpm). Slowly adjusting the speed of the variable frequency motor 10 is not only more energy-saving, but also smoother, which increases the overall service life of the variable frequency motor 10 and the electric drive oil-gas separator.

[0079] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A control method for an electric-driven oil-gas separator combining a pilot indicator and a direct indicator, wherein the electric-driven oil-gas separator has a variable frequency motor, a pressure sensor is provided in the crankcase of a motor vehicle, and the variable frequency motor and the pressure sensor are respectively connected to an on-board ECU through an on-board circuit; the method is characterized in that After the engine is started, a basic data acquisition method and a variable frequency motor operating frequency control method based on the basic data are performed; The maximum operating frequency of the variable frequency motor is defined as MAX, and the minimum operating frequency of the variable frequency motor is defined as MIN; When the engine is initially started, the vehicle ECU controls the operating frequency of the variable frequency motor to (MAX+MIN) / 2; 1. The basic data acquisition method is: ① The on-board ECU collects the crankcase pressure data through the pressure sensor once a second to obtain the current pressure value P0; -1.05 kPa ≤ P0 ≤ -0.95 kPa is the optimal crankcase pressure range; ② Each time the P0 value is collected, if P0 is in the optimal crankcase pressure range, the on-board ECU records the engine speed S1 when the optimal pressure occurs; ③ When the number of S1 is greater than or equal to 10, the on-board ECU takes the average of the last 10 S1 values ​​as the recent optimal engine speed SJ; defines the optimal engine speed SD for calculation, and before the first calculation of SJ, the current S1 value is used as the value of SD; after the first calculation of SJ, the current SJ value is used as the value of SD; ④ The on-board ECU collects the current operating frequency H0 of the variable frequency motor once a second; 2. When P0≤-1.5 kPa or P0≥-0.5 kPa, the variable frequency motor operating frequency control method is started, and the basic data acquisition method is continuously operated; The frequency control method of variable frequency motor is: The on-board ECU obtains the current engine speed S0 every 10 seconds and calculates ⊿H=|{(S0-SD) / SD}×H0|; When P0>0, the on-board ECU adjusts the operating frequency of the variable frequency motor to MAX; When P0 < -2 kPa, the on-board ECU adjusts the operating frequency of the variable frequency motor to MIN; When 0 ≥ P0 ≥ -0.5 kPa, the on-board ECU adjusts the operating frequency of the variable frequency motor to the target value, which is the smaller value between (H0 + ⊿H) and MAX; When -2≤P0≤-1.5 kPa, the on-board ECU adjusts the operating frequency of the variable frequency motor to the target value, which is the larger value between (H0-⊿H) and MIN.

2. The electric drive oil-gas separator control method combining a pilot indicator with a direct indicator according to claim 1 is characterized in that: In the variable frequency motor operating frequency control method, when 0≥P0≥-0.5 kPa and ⊿H≤0.1 H0, the operating frequency of the variable frequency motor is directly adjusted to the corresponding target value; when 0≥P0≥-0.5 kPa and ⊿H>0.1 H0, the operating frequency of the variable frequency motor is gradually increased at a speed of 0.1 H0 / second until the operating frequency of the variable frequency motor is adjusted to the corresponding target value; When -2≤P0≤-1.5 kPa and ⊿H≤0.1 H0, directly adjust the operating frequency of the variable frequency motor to the corresponding target value; when -2≤P0≤-1.5 kPa and ⊿H>0.1 H0, gradually increase the operating frequency of the variable frequency motor at a speed of 0.1 H0 / s until the operating frequency of the variable frequency motor is adjusted to the corresponding target value.

3. The electric drive oil-gas separator control method combining the pilot indicator and the direct indicator according to claim 1 or 2 is characterized in that: The electric-driven oil-gas separator comprises a shell, an air inlet is arranged at the upper part of the shell, the air inlet is used to connect to the upper part of the crankcase, an air outlet is arranged at the lower part of the other side of the shell, the air outlet is used to discharge the filtered gas; a partition structure is arranged at the middle part of the shell, the partition structure and the shell above it form an air inlet cavity, and the partition structure and the shell below it form an air outlet cavity; a vent is arranged at the middle part of the partition structure; An air pump is provided in the air inlet cavity corresponding to the air inlet, the air pump is connected upwardly to the variable frequency motor, the circumferential end surface of the air pump shell is open and used to inhale gas; a plurality of blades for inhaling air during rotation are provided in the air pump shell, the air pump shell is connected downwardly to an air outlet pipe, and the air outlet pipe extends downwardly into the air vent; the partition structure is connected downwardly to a vent cylinder, the vent cylinder encloses the vent and its bottom end is closed; a plurality of air vents are provided on the circumferential side wall of the vent cylinder, a filter cartridge made of filter material is provided on the outer cover of the vent cylinder, a cover cylinder is attached to the circumferential outer wall of the filter cartridge, and the cover cylinder is connected upwardly to the partition structure; A baffle cylinder is arranged upward at the bottom of the shell, the lower end of which is connected to the bottom surface of the shell, the top of which encloses the bottom of the cover cylinder and the filter cylinder, and a connecting port is formed at the top of the baffle cylinder outside the cover cylinder; the shell inside the baffle cylinder is downwardly connected to an oil return port, which is used to connect to the oil pan of the crankcase; The bottom of the shell is in a cone shape with a larger top and a smaller bottom, and the oil return port is arranged at the bottom of the shell cone; a rotating sealing structure is arranged between the vent and the outlet pipe; an oil seepage film is arranged in the baffle cylinder directly below the filter cylinder, and the oil seepage film is higher than the oil return port.

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