Engine crankcase oil-gas separation control method and system

Abstract

The invention relates to an engine crankcase oil-gas separation control method and system which are used for optimizing the oil-gas separation efficiency of an engine crankcase oil-gas separation unit, and the method comprises the steps that the opening control parameter delta P of a gravity one-way valve is determined according to the pressure difference between the gas flow pressure P2 of an outer cavity of the oil-gas separation unit and the gas flow pressure P1 of an inner cavity of the oil-gas separation unit; the liquid level pressure P of the dynamic liquid level H of the engine oil in the rising process is obtained when the oil-gas separation unit operates; when P is smaller than delta P, the gravity one-way valve is controlled to be closed; when P is larger than delta P, the gravity one-way valve is controlled to be opened; and when the gravity one-way valve is opened, the engine oil is discharged, so that the dynamic liquid level H of the engine oil is reduced, and the dynamic liquid level H of the engine oil is kept in small-amplitude fluctuation within a set interval through state switching of the gravity one-way valve. The method has the beneficial effects that the method can be used for improving the type selection efficiency and the control precision of the oil-gas separation system, and improving the one-time success rate and the overall reliability of system development.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle engines, and in particular to an engine crankcase oil-gas separation control method and system. Background Art

[0002] With the development of engines, domestic requirements for engine emissions have been repeatedly improved. People pay more and more attention to the engine's oil-gas separation device and have more and more stringent requirements on the separation effect of the oil-gas separation device. While meeting regulatory emission requirements, the oil-gas separator plays an indelible role in improving engine performance and fuel economy.

[0003] Since the current mainstream scheme structure and design method of the crankcase ventilation system of the current engine are mainly designed and optimized based on past experience and actual machine verification, they are generally extensive. And due to the different selection strategies and design methods in the selection process, the separation efficiency of the oil-gas separation scheme varies greatly, and the long-term stability of the scheme is also very uncertain, which causes a lot of unnecessary repetitions and waste of costs and cycles in product development. Summary of the invention

[0004] The embodiments of the present application provide an engine crankcase oil-gas separation control method and system, which improves the oil-gas separation system selection efficiency and control accuracy by modularizing and finely controlling the oil-gas separation structure, and improves the success rate and overall reliability of system development.

[0005] In a first aspect, an embodiment of the present application provides an engine crankcase oil-gas separation control method, which specifically includes the following steps:

[0006] An engine crankcase oil-gas separation control method is used to optimize the oil-gas separation efficiency of an engine crankcase oil-gas separation unit, the method comprising:

[0007] Determine the opening control parameter ΔP of the gravity check valve according to the pressure difference between the airflow pressure P2 of the outer cavity of the oil-gas separation unit and the airflow pressure P1 of the inner cavity of the oil-gas separation unit; wherein ΔP=P2-P1;

[0008] When the oil-gas separation unit is running, the liquid surface pressure P of the dynamic liquid surface height H of the engine oil is rising;

[0009] When P is less than ΔP, the gravity check valve is controlled to be in a closed state; wherein, when the gravity check valve is in a closed state, the oil continues to accumulate in the oil return chamber, and the dynamic liquid level height H continues to increase;

[0010] When P is greater than ΔP, the gravity one-way valve is controlled to open; wherein, when the gravity one-way valve is in the open state, the oil is discharged so that the dynamic liquid level H of the oil decreases, and the dynamic liquid level H of the oil is maintained within a set range with small fluctuations by switching the state of the gravity one-way valve.

[0011] Furthermore, the engine crankcase oil-gas separation control method proposed in the embodiment of the present invention also has the following additional technical features:

[0012] Preferably, the opening control parameter ΔP of the gravity one-way valve is ≤0.5 KPa.

[0013] Preferably, the oil return hole arranged in the engine crankcase has a height interval ranging from 10 mm below the outlet cylinder head cover assembly plane.

[0014] Preferably, the stable blowby volume of the engine crankcase is ≤80 L / min, and the limit blowby volume is ≤100 L / min.

[0015] Preferably, the volume range of the oil return chamber volume V is 0.1-0.15L.

[0016] In a second aspect, the embodiment of the present application provides a crankcase oil-gas separation control system. The system comprises: an air inlet unit, a rough separation unit, a fine separation unit, an oil return unit and an air outlet structure unit; wherein the air inlet unit is provided with an air inlet, and the rough separation unit is provided with a baffle.

[0017] Preferably, the baffle includes at least two partitions which are respectively vertically arranged at the upper and lower ends of the coarse separation unit cavity, so that the gas flow in the cavity of the coarse separation unit is wavy.

[0018] Preferably, the oil return unit comprises a deep V-shaped liquid level rapid rise zone at the lower end and a wide area liquid level slow rise zone above the deep V-shaped liquid level rapid rise zone, and the gravity single-phase valve is arranged at the bottom of the oil return unit.

[0019] Preferably, the air inlet is arranged at a height lower than the bottom surface of the cavity of the coarse separation unit.

[0020] The beneficial effects of the present invention include at least: by using the parameter control method, by setting the core control parameters, controlling or setting the opening control parameter ΔP (coarse / fine separation unit pressure difference) of the one-way valve, the dynamic height H of the oil accumulation after the fine separation unit, and the volume V of the oil return chamber for storing the oil separated by the fine separation unit, the oil-gas separation structure is modularized and refined. The patent of the present invention can be used to improve the selection efficiency and control accuracy of the oil-gas separation system, and improve the one-time success rate and overall reliability of system development.

[0021] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0023] Figure 1 Schematic diagram of the pressure difference relationship of the engine crankcase oil-gas separation unit proposed in the first embodiment of the present invention;

[0024] Figure 2 Schematic diagram of the deterioration of oil content in the crankcase cavity;

[0025] Figure 3 It is a schematic diagram of a vertically sinking air inlet structure proposed in an embodiment of the present invention;

[0026] Figure 4 It is a schematic diagram of a side-opening air inlet structure proposed in an embodiment of the present invention;

[0027] Figure 5 1 is a schematic diagram of a structure of a built-in baffle-type air inlet proposed in an embodiment of the present invention;

[0028] Figure 6 Schematic diagram of the oil return unit structure proposed in an embodiment of the present invention;

[0029] Figure 7 It is a schematic diagram of the structure of a cylinder head cover assembly with an integrated oil-gas separation unit designed based on the present invention;

[0030] Description of main component symbols: DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0032] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0033] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0034] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, "A and / or B" can represent: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0035] The current mainstream scheme structure and design method of the crankcase ventilation system of the current engine are mainly designed and optimized based on past experience and actual machine verification, which is generally extensive. In addition, due to different selection strategies and design methods in the selection process, the separation efficiency of the oil-gas separation scheme varies greatly, and the long-term stability of the scheme is also very uncertain, causing a lot of unnecessary repetitions and waste of costs and cycles in product development. It is mainly manifested in:

[0036] 1. The current design scheme is mainly based on experience development, overly dependent on design and development experience, with a long development cycle and significant differences in design schemes;

[0037] 2. The product design plan is not stable, mainly manifested in:

[0038] 1) The initial separation effect is poor and cannot meet development requirements;

[0039] 2) Poor robustness. The oil-gas separation effect deteriorates significantly with the durability time, and the separation effect does not meet the requirements in the middle and late stages of the product life;

[0040] 3) Under extreme operating conditions, such as continuous rated point conditions, the oil and gas separation efficiency deteriorates and returns to normal under normal conditions.

[0041] To this end, the present invention proposes an engine crankcase oil-gas separation control method to solve the above-mentioned problem.

[0042] It can be understood that the main working principle of the oil-gas separation technology of the engine crankcase is fluid mechanics, and according to the Bernoulli equation of fluid mechanics:

[0043]

[0044] Where p, ρ, v are the pressure, density and velocity of the fluid; h is the vertical height; g is the weight acceleration; and C is an unchanging constant.

[0045] For gases, gravity can be neglected and the Bernoulli equation can be simplified to:

[0046]

[0047] According to the above equation, we can conclude that: the lower the flow rate in the gas, the greater the pressure; the higher the flow rate, the lower the pressure. Figure 1 , which is a schematic diagram of the pressure difference relationship of the oil-gas separation unit of the crankcase cross section in the embodiment of the present invention. The present invention specifically sets up the engine crankcase oil-gas separation control method, which specifically includes:

[0048] The process includes the following steps:

[0049] Step S10, determining the opening control parameter ΔP of the gravity check valve according to the pressure difference between the airflow pressure P2 of the outer cavity of the oil-gas separation unit and the airflow pressure P1 of the inner cavity of the oil-gas separation unit.

[0050] like Figure 1 As shown, according to the Bernoulli equation, the outer cavity (lower layer) of the gas separation unit has a small structural resistance, a relatively low flow velocity, and a high relative pressure (P2); in the inner cavity of the oil-gas separation unit, the fluid needs to flow through the coarse separation and fine separation structures, which have a large structural resistance and a fast flow velocity. After the gas reaches this point, the relative pressure (P1) is low, and the two airflows form a pressure difference (ΔP) at the gravity one-way valve at the bottom of the oil return hole. Among them, ΔP = P2-P1;

[0051] Step S20, obtaining the liquid surface pressure P of the dynamic liquid surface height H of the engine oil during the rising process when the oil-gas separation unit is running.

[0052] It can be understood that the liquid surface pressure P can be obtained according to the liquid pressure difference formula:

[0053] P=ρgH

[0054] Where P is the pressure of the liquid, ρ is the density of the liquid, and is taken as 0.91×10 3 kg / m 3 ; g is the acceleration due to gravity, H is the dynamic height of the liquid;

[0055] Step S30: when P is less than ΔP, the gravity one-way valve is controlled to be in a closed state.

[0056] Step S31, when P is greater than ΔP, the gravity one-way valve is controlled to open.

[0057] It should be noted that when the gravity check valve is in the closed state, the engine oil continues to accumulate in the oil return chamber, and the dynamic liquid level H continues to rise; when the dynamic height H of the accumulated oil reaches a certain height, the liquid pressure P>ΔP formed by it, at this time the gravity check valve of the oil return hole opens, and the dynamic height H of the oil drops back until the gravity valve closes, and the dynamic height of the oil rises again, and so on. Through the state switching of the gravity check valve, the dynamic liquid level H of the oil is maintained within the set range with small fluctuations.

[0058] In summary, the engine crankcase oil-gas separation control method provided by the present invention obtains the opening control parameter ΔP of the gravity check valve, the dynamic oil level H and the liquid level pressure P under the corresponding state, and compares the difference between the two parameters to realize the opening and closing of the gravity check valve. As a result, the dynamic oil level H can be in a relatively stable range. Thereby achieving the purpose of modularization and refined control of the oil-gas separation structure. The patent of the present invention can be used to improve the selection efficiency and control accuracy of the oil-gas separation system, and improve the one-time success rate and overall reliability of system development.

[0059] It is understandable that the greater the pressure difference ΔP, the higher the corresponding requirement H, and the higher the layout requirement of the structural height direction of the corresponding oil-gas separation unit. When it comes to the design requirements of the engine, the control parameters can be adjusted according to the working environment requirements to achieve the purpose of precise research and development.

[0060] Preferably, in the embodiment of the present invention, due to the constraints of the flow resistance of the engine crankcase structure, the intake pipe pressure and the compactness of the structure, the opening control parameter ΔP of the gravity check valve is required to be ≤0.5Kpa in the present invention.

[0061] Furthermore, under the premise that the opening control parameter ΔP of the gravity check valve is ≤ 0.5 Kpa, the dynamic height H (such as Figure 1 Schematic diagram) needs to be ≥56mm. In actual applications, the structural height from the assembly surface of the cylinder head cover to the fine filter unit oil baffle (to prevent the filtered oil from being swept away by the high-speed airflow) is difficult to reach more than 56mm. In order to achieve effective oil return efficiency, the oil return hole often protrudes from the cylinder head cover assembly surface. In order to deal with the layout compatibility problems and collision damage of the oil return hole during transportation and assembly, and the detachment of the gravity check valve, etc., this solution often causes problems such as layout compatibility, collision damage of the oil return hole during transportation and assembly, and the detachment of the gravity check valve. In this case, according to the actual layout space, the dynamic height of the oil return hole is set at 45-55mm, that is, the setting height range of the oil return hole set in the engine crankcase is within 10mm below the assembly plane of the outlet cylinder head cover.

[0062] It should be further explained that, under the strategy setting of ΔP≤0.5KPa, setting the dynamic height of the oil return hole lower than 56mm will cause a more serious problem, that is, due to the insufficient oil return height margin, the gravity check valve will not open or open late. If there is no corresponding balancing measure, the consequences will be more serious. Figure 2 As shown in the figure, under certain specific continuous operating conditions, the oil-gas separation efficiency will deteriorate significantly in an instant: the high-speed airflow after fine separation will sweep away the excessively accumulated oil, causing the oil content in the crankcase ventilation system to rise sharply.

[0063] To avoid the above situation, the control strategy in the embodiment of the present invention can be adjusted to balance the late opening and non-opening of the gravity check valve by adjusting the oil storage volume V and the structural type of the oil return chamber. The specific strategy is as follows: the stable blowby volume of the engine crankcase is ≤80L / min, and the limit blowby volume is ≤100L / min.

[0064] The embodiment of the present invention also provides a crankcase oil-gas separation control system, which is used to implement the above-mentioned embodiments and preferred embodiments, and will not be repeated here. As used below, the terms "module", "unit", "sub-unit", etc. can implement a combination of software and / or hardware of predetermined functions. Although the devices described in the following embodiments are preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable. The system includes: an air inlet unit, a coarse separation unit, a fine separation unit, an oil return unit, and an air outlet structure unit.

[0065] The air inlet unit is provided with an air inlet, and the air inlet is arranged at a height lower than the bottom surface of the cavity of the coarse separation unit. Figure 3 , Figure 4 , Figure 5 As shown. By arranging it between the cams of the two camshafts at the front end, the intake port is sunken to avoid splashing oil, so as to minimize the liquid oil entering the rough separation chamber. The intake unit is a rectangular structure, and its structural form is as follows Figure 3 , Figure 4 When the splashing oil cannot be completely avoided due to the limitation of the layout structure, a baffle can be set above the air inlet to play a blocking role, as shown in the following figure. Figure 5 The baffle structure is arranged as shown.

[0066] In addition, the rough separation unit is provided with a baffle, and the baffle is a two-stage maze structure (such as Figure 1 The baffle structure is provided to disturb the inlet air, reduce the gas flow rate in the rough separation unit, and optimize the rough separation efficiency.

[0067] This is an example but not a limitation. In actual selection, the rough separation efficiency can be optimized by adjusting the baffle position according to the specific situation.

[0068] Furthermore, in the embodiment of the present invention, the fine separation unit is designed as a detachable independent module to support rapid selection; the diameter and number of impact holes are standardized. Impact hole diameter: 2mm and 2.5mm; number of holes: 7 to 14 (even-number holes are preferred); the coarse / fine separation unit scheme is designed and selected according to CFD analysis, and the pressure difference ΔP level before and after the fine filter unit is adjusted under the premise of ensuring a separation efficiency of ≥99.5%, and the acceptance standard is: the maximum pressure difference is maintained at 0.5±0.3KPa.

[0069] The oil return hole of the oil return unit shall not exceed the assembly surface of the cylinder head cover assembly. In the extreme case, under the premise of meeting the function, it cannot protrude from the cylinder head cover assembly surface by 10mm at most; the height of the oil return hole from the fine separation oil baffle (i.e. dynamic oil height) H: the selection range of height H is: 50±5mm; the specific requirements are as follows:

[0070] The oil return chamber (oil return unit) is divided into two levels of height (such as Figure 6 Specifically, it includes a deep V-shaped liquid level rapid rising area H1 at the lower end and a wide area liquid level slow rising area H2 above the deep V-shaped liquid level rapid rising area. A gravity single-phase valve is provided at the bottom of the oil return unit.

[0071] H1 is the rapid liquid level lifting area, which is used to quickly build up liquid pressure and shorten the opening time of the gravity check valve. H1≥25mm;

[0072] H2 liquid level slow rise area, the main purpose: under the steady-state condition with large ΔP, to slow down the liquid level rise rate and prevent the liquid level from exceeding the height of the fine filter unit oil baffle. Acceptance standard: oil storage chamber volume V ≥ 0.1 ~ 0.15L;

[0073] Parametric Control:

[0074] Matching control of pressure difference ΔP before and after fine separation, oil return hole height H and oil return chamber volume V:

[0075] The designed maximum pressure difference ΔP≤0.5±0.3KPa, the oil return hole height H≥55mm, basically meeting the ΔP opening height, and the oil return chamber oil storage volume V≥0.1L;

[0076] The designed maximum pressure difference ΔP is ≤ 0.5 ± 0.3 KPa, the oil return hole height H = 45 ~ 55, which is more than 80% of the ΔP opening height, and the oil storage volume of the oil return chamber V = 0.1-0.15L. Through the delayed compensation strategy, when the pressure difference drops, the power check valve opens to achieve rapid oil return.

[0077] See also Figure 7 , which is a cylinder head cover assembly with an integrated oil-gas separation unit designed based on the requirements of the present invention. The cylinder head cover assembly is a plastic body structure, and the air inlet is a vertically sunken structure, which is placed in front of the first gear camshaft. The coarse separation unit is divided into two levels of baffles, the front lower and the rear upper; the distance between the two gears is 22mm; according to the separation efficiency and pressure difference selection, the impact hole specification of the fine filter unit is 2.5mm, and the number is 10. The steady-state pressure difference before and after the fine filter is 0.5KPa, the pressure difference fluctuation range is 0~0.8KPa, the return oil height is 56.3mm, and the oil storage chamber volume is 0.102L; under the comprehensive durability condition, the maximum oil blowby amount before and after the test is stable at <0.6g / h, and the oil blowby amount before and after the test is basically stable without deterioration.

[0078] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. An engine crankcase oil-gas separation control method for optimizing the oil-gas separation efficiency of an engine crankcase oil-gas separation unit, characterized in that: The method comprises: Determine the opening control parameter ΔP of the gravity check valve according to the pressure difference between the airflow pressure P2 of the outer cavity of the oil-gas separation unit and the airflow pressure P1 of the inner cavity of the oil-gas separation unit; wherein ΔP=P2-P1; When the oil-gas separation unit is running, the liquid surface pressure P of the dynamic liquid surface height H of the engine oil is rising; When P is less than ΔP, the gravity check valve is controlled to be in a closed state; wherein, when the gravity check valve is in a closed state, the oil continues to accumulate in the oil return chamber, and the dynamic liquid level height H continues to increase; When P is greater than ΔP, the gravity one-way valve is controlled to open; wherein, when the gravity one-way valve is in the open state, the oil is discharged so that the dynamic liquid level H of the oil decreases, and the state of the gravity one-way valve is switched so that the dynamic liquid level H of the oil is maintained within a set range with small fluctuations.

2. The engine crankcase oil-gas separation control method according to claim 1, characterized in that: The opening control parameter ΔP of the gravity one-way valve is ≤0.5 KPa.

3. The engine crankcase oil-gas separation control method according to claim 1, characterized in that: The oil return hole arranged in the engine crankcase is arranged within a height interval range of 10 mm below the assembly plane of the cylinder head cover.

4. The engine crankcase oil-gas separation control method according to claim 1, characterized in that: The stable blowby volume of the engine crankcase is ≤80L / min, and the limit blowby volume is ≤100L / min.

5. A crankcase oil-gas separation control system, used to implement the method according to any one of claims 1 to 4, the system comprising: An air inlet unit, a rough separation unit, a fine separation unit, an oil return unit and an air outlet structure unit; wherein the air inlet unit is provided with an air inlet, and the rough separation unit is provided with a baffle.

6. The crankcase oil-gas separation control system according to claim 5, characterized in that: The baffle includes at least two baffles which are respectively vertically arranged at the upper and lower ends of the coarse separation unit cavity, so that the gas in the cavity of the coarse separation unit flows in a wave shape.

7. The crankcase oil-gas separation control system according to claim 5, characterized in that: The oil return unit comprises a deep V-shaped liquid level rapid rising area at the lower end and a wide area liquid level slow rising area above the deep V-shaped liquid level rapid rising area. The gravity single-phase valve is arranged at the bottom of the oil return unit.

8. The crankcase oil-gas separation control system according to claim 5, characterized in that: The air inlet is arranged at a height lower than the bottom surface of the cavity of the rough separation unit.

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