Engine control method and hpdi engine

Abstract

The application provides an engine control method and an HPDI engine. The engine control method is suitable for an HPDI engine, and comprises the following steps: obtaining an actual excess air coefficient λ during actual operation of the HPDI engine; judging the combustion easiness of fuel in a cylinder body of the HPDI engine according to the actual excess air coefficient λ; when the fuel is not easy to combust, controlling the rotation speed of a first pump body to be reduced to reduce the flow of lubricating oil; and / or controlling the rotation speed of a second pump body to be reduced to reduce the flow of cooling liquid. The application solves the problem of excessive methane emission of an engine in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engines, in particular to an engine control method and an HPDI engine. BACKGROUND

[0002] The diesel natural gas dual-fuel HPDI engine has lower carbon emission than the traditional diesel engine and higher thermal efficiency than the spark-ignited natural gas engine, and thus meets the low-carbon emission trend, so the HPDI engine has good application prospect. Specifically, the HPDI engine is a high-pressure direct-injection diesel pilot natural gas engine, and its specific working principle is as follows: 5% diesel is injected into the cylinder before the compression top dead center to ignite, and 95% natural gas is injected into the main fuel combustion to do work at a pressure of 300 bar. On the structure, only a high-pressure direct-injection nozzle needs to be installed on the traditional diesel engine.

[0003] However, the HPDI engine generally adopts a lean combustion route. Since the HPDI engine generally adopts a compression ignition method to ignite fuel, the air quantity at this time needs to be much larger than the fuel quantity. In this way, during the operation of the engine, the methane is prone to not being ignited, so that the methane emission is high. At present, there is no effective and reliable post-processing method to eliminate methane, so it is urgent to find corresponding measures to reduce the methane emission to prevent the impact on the environment. SUMMARY

[0004] The main purpose of the present application is to provide an engine control method and an HPDI engine to solve the problem of high methane emission of the engine in the prior art.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present application, an engine control method is provided, which is suitable for an HPDI engine. The HPDI engine includes a cylinder block and a piston, and the piston is movably arranged on the cylinder block. The HPDI engine includes a first flow pipeline for connecting with the piston, the first flow pipeline is used for introducing lubricating oil into the piston, and a first pump body is arranged on the first flow pipeline. The outer side of the cylinder block is sleeved with a cylinder block water jacket, and the HPDI engine further includes a second flow pipeline for connecting with the cylinder block water jacket, the second flow pipeline is used for introducing cooling liquid into the cylinder block water jacket, a second pump body is arranged on the second flow pipeline, and the engine control method includes: obtaining an actual excess air coefficient λ during the actual operation of the HPDI engine; judging the ease of combustion of fuel in the cylinder block of the HPDI engine according to the actual excess air coefficient λ; when the fuel is not easy to burn, controlling the rotation speed of the first pump body to be reduced to reduce the flow of the lubricating oil; and / or controlling the rotation speed of the second pump body to be reduced to reduce the flow of the cooling liquid.

[0006] Further, the method for judging the combustion ease of the fuel comprises: obtaining a predetermined excess air coefficient λ1; comparing the size relationship between the actual excess air coefficient λ and the predetermined excess air coefficient λ1; when the actual excess air coefficient λ is greater than the predetermined excess air coefficient λ1, controlling the rotation speed of the first pump body and / or the rotation speed of the second pump body to decrease, otherwise, maintaining the rotation speed of the first pump body and the second pump body unchanged.

[0007] Further, the method for obtaining the predetermined excess air coefficient λ1 comprises: controlling the HPDI engine to be in a preset operating state, and recording a plurality of experimental excess air coefficients and the corresponding methane emission amounts under each experimental excess air coefficient during the process of the HPDI engine in the preset operating state; according to the corresponding relationship between the plurality of experimental excess air coefficients and the methane emission amounts, selecting the excess air coefficient corresponding to the growth rate of the methane emission amount greater than a predetermined value as the predetermined excess air coefficient λ1.

[0008] Further, the method for obtaining the predetermined excess air coefficient λ1 further comprises: drawing a corresponding relationship diagram between the methane emission amount and the experimental excess air coefficient; selecting the inflection point in the corresponding relationship diagram as the predetermined excess air coefficient λ1; wherein the inflection point of the corresponding relationship diagram is the inflection point of the growth rate of the methane emission amount.

[0009] Further, when the fuel is in the condition not easy to be combusted, the engine control method comprises: controlling the rotation speed of the first pump body to decrease to a first minimum preset value; and / or, controlling the rotation speed of the second pump body to decrease to a second minimum preset value.

[0010] Further, the engine control method further comprises: controlling the HPDI engine to be in a preset operating state; during the process of the preset operating state, the HPDI engine has a plurality of preset operating conditions, the rotation speed and the torque of the plurality of preset operating conditions are all different, in each preset operating condition, gradually decreasing the rotation speed of the first pump body and the rotation speed of the second pump body until the HPDI engine occurs a cylinder pulling; under each preset operating condition, recording the first lowest rotation speed critical value of the first pump body and the second lowest rotation speed critical value of the second pump body when the HPDI engine occurs the cylinder pulling; during the actual operation process of the HPDI engine, according to the actual operating condition of the HPDI engine, according to the first lowest rotation speed critical value of each preset operating condition, obtaining the corresponding first minimum preset value; according to the second lowest rotation speed critical value of each preset operating condition, obtaining the corresponding second minimum preset value.

[0011] Further, after obtaining the first minimum preset value and the second minimum preset value, the method further comprises: multiplying the first minimum rotational speed threshold value by a first safety coefficient a to obtain the first minimum preset value of the rotational speed of the first pump body; and multiplying the second minimum rotational speed threshold value by a second safety coefficient b to obtain the second minimum preset value of the rotational speed of the second pump body; wherein the first safety coefficient a and the second safety coefficient b are both greater than 1.

[0012] Further, the first safety coefficient a is in a range of 1.5 to 2.5; and / or the second safety coefficient b is in a range of 1.5 to 2.5.

[0013] According to another aspect of the present application, there is provided an HPDI engine suitable for the engine control method described above, the HPDI engine comprising: a cylinder block; a cylinder block water jacket sleeved outside the cylinder block, the HPDI engine further comprising a second flow pipeline connected with the cylinder block water jacket, the second flow pipeline being used for passing cooling liquid, and a second pump body being arranged on the second flow pipeline; a piston movably arranged in the cylinder block, the HPDI engine comprising a first flow pipeline connected with the piston, the first flow pipeline being used for passing engine oil, and a first pump body being arranged on the first flow pipeline; wherein a first thermal insulation coating is arranged on an inner wall surface of the piston.

[0014] Further, the cylinder block comprises a cylinder block main body and a cylinder head part connected with each other, the cylinder head part and the piston being arranged at two ends of the cylinder block main body respectively, the cylinder block water jacket comprises a cylinder head water jacket and a main body water jacket, the cylinder head water jacket being sleeved on the cylinder head part, and the main body water jacket being sleeved on the cylinder block main body; wherein a second thermal insulation coating is arranged on a side wall surface of the cylinder head water jacket close to the piston.

[0015] The technical scheme of the application provides an engine control method, which is suitable for an HPDI engine, the HPDI engine comprising a cylinder body and a piston, the piston being movably arranged on the cylinder body, the HPDI engine comprising a first flow pipeline connected with the piston, the first flow pipeline being used for feeding lubricating oil to the piston, and the first flow pipeline being provided with a first pump body; the outer side of the cylinder body is sleeved with a cylinder water jacket, and the HPDI engine further comprises a second flow pipeline connected with the cylinder water jacket, the second flow pipeline being used for feeding cooling liquid to the cylinder water jacket, and the second flow pipeline being provided with a second pump body, the engine control method comprising: obtaining an actual excess air coefficient λ during actual operation of the HPDI engine; judging the ease of combustion of fuel in the cylinder body of the HPDI engine according to the actual excess air coefficient λ; when the fuel is in a state of not being easy to combust, the rotation speed of the first pump body is controlled to be reduced to reduce the flow of the lubricating oil, and / or the rotation speed of the second pump body is controlled to be reduced to reduce the flow of the cooling liquid, so that when the fuel is in a state of not being easy to combust, it indicates that the methane combustion at this time is incomplete, and the unburned methane is easy to be discharged into the atmosphere, at this time, the application reduces the flow of the cooling liquid and / or the lubricating oil to reduce the cooling amount of the cylinder body, improve the combustion chamber wall temperature, reduce the risk of methane wall quenching, so as to ensure that the methane in the cylinder body can be fully combusted, thereby reducing the emission amount of methane. BRIEF DESCRIPTION OF DRAWINGS

[0016] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the application, and together with the description of the exemplary embodiments of the application given below, make an explanation of the application, and do not constitute an improper limitation of the application. In the drawings:

[0017] Figure 1 A flowchart of an embodiment of the engine control method according to the application is shown;

[0018] Figure 2 A structural schematic diagram of an embodiment of the engine according to the application is shown;

[0019] Figure 3 A corresponding relationship diagram between the methane emission amount and the excess air coefficient of the engine control method according to the application is shown.

[0020] Among the above drawings, the following reference signs are included:

[0021] 1, piston; 100, first flow pipeline; 101, first pump body; 2, cylinder water jacket; 200, second flow pipeline; 201, second pump body; 21, cylinder head water jacket; 20, main body water jacket; 102, first thermal insulation coating; 202, second thermal insulation coating. DETAILED DESCRIPTION

[0022] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0023] Please refer to Figures 1 to 3 The present application provides an engine control method, which is suitable for an HPDI engine, the HPDI engine comprising a cylinder block and a piston 1, the piston 1 being movably arranged on the cylinder block, the HPDI engine comprising a first flow pipeline 100 for being connected with the piston 1, the first flow pipeline 100 being used for feeding lubricating oil to the piston 1, and a first pump body 101 being arranged on the first flow pipeline 100; an outer side of the cylinder block is sleeved with a cylinder block water jacket 2, and the HPDI engine further comprises a second flow pipeline 200 for being connected with the cylinder block water jacket 2, the second flow pipeline 200 being used for feeding cooling liquid to the cylinder block water jacket 2, and a second pump body 201 being arranged on the second flow pipeline 200, the engine control method comprising: obtaining an actual excess air coefficient λ during actual operation of the HPDI engine; judging a combustion easiness of fuel in the cylinder block of the HPDI engine according to the actual excess air coefficient λ; when the fuel is in a state of not being easy to combust, controlling a rotation speed of the first pump body 101 to be reduced so as to reduce a flow of the lubricating oil, and / or controlling a rotation speed of the second pump body 201 to be reduced so as to reduce a flow of the cooling liquid, so that when the fuel is in the state of not being easy to combust, it indicates that methane combustion at this time is incomplete, and uncombusted methane is easy to be discharged into the atmosphere, at this time, the present application reduces the flow of the cooling liquid and / or the lubricating oil so as to reduce a cooling amount of the cylinder block, increase a combustion chamber wall surface temperature, reduce a risk of methane wall surface quenching, so as to ensure that methane in the cylinder block can be fully combusted, thereby reducing an emission amount of methane.

[0024] Wherein, the excess air coefficient = actual air quantity / required air quantity, which is an important parameter of a reaction fuel and air matching ratio in the engine; the fuel of the HPDI engine comprises diesel and natural gas; the lubricating oil is engine oil.

[0025] Specifically, the excess air coefficient can be obtained by an electronic control unit ECI of the automobile, the actual intake amount in the cylinder block and the actual fuel injection amount are obtained by the electronic control unit (ECU) of the automobile, and the actual excess air coefficient λ is obtained according to the actual intake amount in the cylinder block and the actual fuel injection amount.

[0026] Wherein, as shown in Figure 1 The actual intake amount is an air intake amount, and the actual fuel injection amount comprises a diesel injection amount and a natural gas injection amount.

[0027] In order to realize the judgment of the combustion ease of the fuel, in the present application, the method for judging the combustion ease of the fuel comprises: obtaining a predetermined excess air coefficient λ1; comparing the size relationship between the actual excess air coefficient λ and the predetermined excess air coefficient λ1; when the actual excess air coefficient λ is greater than the predetermined excess air coefficient λ1, the rotation speed of the first pump body 101 and / or the rotation speed of the second pump body 201 is reduced, otherwise, the rotation speed of the first pump body 101 and the second pump body 201 is maintained unchanged.

[0028] The predetermined excess air coefficient λ1 is obtained in the engine emission experiment, and the predetermined excess air coefficient λ1 of different types of HPDI engines is different.

[0029] In order to obtain the predetermined excess air coefficient λ1, the method for obtaining the predetermined excess air coefficient λ1 comprises: controlling the HPDI engine to be in a preset operating state, and recording a plurality of experimental excess air coefficients in the process of the HPDI engine in the preset operating state and the corresponding methane emission amount under each experimental excess air coefficient; according to the corresponding relationship between the plurality of experimental excess air coefficients and the methane emission amount, selecting the excess air coefficient corresponding to the growth rate of the methane emission amount greater than a predetermined value as the predetermined excess air coefficient λ1.

[0030] Optionally, the predetermined excess air coefficient λ1 is 2.0; or the value range of the predetermined excess air coefficient λ1 is between 3.5 and 4.0; the predetermined excess air coefficient λ1 of different engine types is different.

[0031] In the process of engine operation, the data obtained with the change of engine operating conditions becomes universal data, therefore, the plurality of experimental excess air coefficients of the HPDI engine in the process of the preset operating state can be recorded as the universal data of the experimental excess air coefficient. As shown in the figure, Figure 1 CH4 universal represents a plurality of methane emission amounts obtained with the change of engine operating conditions in the process of engine emission experiment; λ universal represents a plurality of excess air coefficients obtained with the change of engine operating conditions in the process of engine emission experiment.

[0032] As shown in the figure, Figure 3 In the present application, the method for obtaining the predetermined excess air coefficient λ1 further comprises: drawing a corresponding relationship diagram between the methane emission amount and the experimental excess air coefficient; selecting the inflection point in the corresponding relationship diagram as the predetermined excess air coefficient λ1; wherein the inflection point of the corresponding relationship diagram is the inflection point of the growth rate of the methane emission amount, in this way, the predetermined excess air coefficient λ1 can be intuitively selected, and the experimental time is saved.

[0033] Specifically, the growth rate of the methane emission before the inflection point is less than the growth rate of the methane emission after the inflection point; wherein, in the corresponding relationship diagram between the methane emission and the experimental excess air coefficient, the excess air coefficient is the X axis, the methane emission is the Y axis, and the growth rate of the methane emission is the slope of the linear curve fitted by the multiple linear points in the formula. Figure 3

[0034] In order to prevent the engine from being damaged due to the occurrence of engine scuffing during the process of reducing the flow of the cooling liquid, when the fuel is not easy to burn, the engine control method includes: controlling the rotation speed of the first pump body 101 to reduce to a first minimum preset value; and / or, controlling the rotation speed of the second pump body 201 to reduce to a second minimum preset value, so that the first pump body and the second pump body do not reduce any more after reducing to the minimum preset value, preventing the engine from being damaged due to the occurrence of engine scuffing, and ensuring the reliability of the engine operation while implementing the control method of reducing the rotation speed of the first pump body and the second pump body.

[0035] In order to select appropriate first minimum preset values and second minimum preset values, the engine control method further includes: controlling the HPDI engine to be in a preset operating state; during the process of the preset operating state, the HPDI engine has multiple preset operating conditions, and the rotation speed and torque of the multiple preset operating conditions are all different, in each preset operating condition, gradually reducing the rotation speed of the first pump body 101 and the rotation speed of the second pump body 201 until the HPDI engine occurs scuffing; recording the first minimum rotation speed critical value of the first pump body 101 and the second minimum rotation speed critical value of the second pump body 201 when the HPDI engine occurs scuffing under each preset operating condition; during the actual operation of the HPDI engine, according to the actual operating condition of the HPDI engine, according to the first minimum rotation speed critical value of each preset operating condition, obtaining the corresponding first minimum preset value; according to the second minimum rotation speed critical value of each preset operating condition, obtaining the corresponding second minimum preset value.

[0036] During the operation of the engine, the data obtained as the engine operating condition changes becomes universal data; therefore, the first minimum rotation speed critical value of each preset operating condition in the present application can be recorded as universal data of the first minimum rotation speed critical value, and the second minimum rotation speed critical value of each preset operating condition can be recorded as universal data of the second minimum rotation speed critical value, and the universal data of the first minimum rotation speed critical value and the universal data of the second minimum rotation speed critical value are both recorded as MAP0.

[0037] ​Further, after obtaining the first minimum preset value and the second minimum preset value, the method further comprises: multiplying the first minimum speed critical value by a first safety coefficient a to obtain the first minimum preset value of the rotation speed of the first pump body 101; multiplying the second minimum speed critical value by a second safety coefficient b to obtain the second minimum preset value of the rotation speed of the second pump body 201; wherein the first safety coefficient a and the second safety coefficient b are both greater than 1. In this way, the minimum speed critical value is multiplied by a safety coefficient to obtain the minimum preset value of the pump body, which further ensures the safety of the engine during the implementation of the engine control method.

[0038] In the present application, the universal data of the first minimum preset value and the universal data of the second minimum preset value are both recorded as MAP1, which is obtained by multiplying MAP0 by a safety coefficient.

[0039] As shown in Figure 1 , the current rotation speed torque MAP represents a plurality of rotation speed torques obtained during actual operation as the operating conditions of the engine change, which is referred to as universal data of rotation speed torque.

[0040] Optionally, the first safety coefficient a has a value range of 1.5 to 2.5; and / or the second safety coefficient b has a value range of 1.5 to 2.5.

[0041] Please refer to Figure 2 , the present application also provides an HPDI engine suitable for the above-mentioned engine control method, the HPDI engine comprising: a cylinder block; a cylinder block water jacket 2, the cylinder block water jacket 2 being sleeved outside the cylinder block, the HPDI engine further comprising a second flow pipe 200 connected with the cylinder block water jacket 2, the second flow pipe 200 being used for passing in cooling liquid, the second flow pipe 200 being provided with a second pump body 201; a piston 1, the piston 1 being movably arranged in the cylinder block, the HPDI engine comprising a first flow pipe 100 connected with the piston 1, the first flow pipe 100 being used for passing in engine oil, the first flow pipe 100 being provided with a first pump body 101; wherein the inner wall surface of the piston 1 is provided with a first thermal insulation coating 102, so that in the process of reducing the flow of the cooling liquid, the temperature in the cylinder block can be further ensured by the first thermal insulation coating 102, the quenching phenomenon of methane in the cylinder is prevented, the methane combustion is sufficient, and the methane emission is reduced.

[0042] Wherein, the first pump body 101 communicates with the oil hole of the piston, and the first pump body 101 is a variable flow oil pump; the second pump body 201 is a variable flow water pump.

[0043] Further, the cylinder body comprises a cylinder body and a cylinder cover part connected with each other, the cylinder cover part and the piston 1 are arranged at two ends of the cylinder body respectively, the cylinder water jacket 2 comprises a cylinder cover water jacket 21 and a body water jacket 20, the cylinder cover water jacket 21 is sleeved on the cylinder cover, and the body water jacket 20 is sleeved on the cylinder body; wherein a second heat insulation coating 202 is arranged on a side wall surface of the cylinder cover water jacket 21 close to the piston 1, so that through mutual cooperation of the first heat insulation coating 102 and the second heat insulation coating 202, in the process of reducing the flow of the cooling liquid and the lubricating oil, the temperature in the cylinder body is further ensured, the methane combustion is sufficient, and the methane emission amount is reduced.

[0044] Wherein, the thermal conductivity coefficient of the material of the first heat insulation coating 102 is less than the thermal conductivity coefficient of the piston, and the thermal conductivity coefficient of the material of the second heat insulation coating 202 is less than the thermal conductivity coefficient of the cylinder cover water jacket 21; in order to make the connection between the first heat insulation coating and the piston stable, a first transition layer is arranged between the first heat insulation coating and the piston, the thermal conductivity coefficient of the first transition layer can be changed, so that the first heat insulation coating and the piston are bonded together through the first transition layer, and the second heat insulation coating and the cylinder cover water jacket are arranged with a second transition layer, the thermal conductivity coefficient of the second transition layer can be changed, so that the second heat insulation coating and the piston are bonded together through the second transition layer.

[0045] From the above description, it can be seen that the above-mentioned embodiments of the present application realize the following technical effects:

[0046] The application provides an engine control method, which is suitable for an HPDI engine, the HPDI engine comprising a cylinder body and a piston 1, the piston 1 being movably arranged on the cylinder body, the HPDI engine comprising a first flow pipeline 100 for being connected with the piston 1, the first flow pipeline 100 being used for feeding lubricating oil to the piston 1, and the first flow pipeline 100 being provided with a first pump body 101; an outer side of the cylinder body is sleeved with a cylinder jacket 2, and the HPDI engine further comprises a second flow pipeline 200 for being connected with the cylinder jacket 2, the second flow pipeline 200 being used for feeding cooling liquid to the cylinder jacket 2, and the second flow pipeline 200 being provided with a second pump body 201, and the engine control method comprises the following steps: in the actual operation process of the HPDI engine, an actual excess air coefficient λ is obtained; according to the actual excess air coefficient λ, the combustion easiness of fuel in the cylinder body of the HPDI engine is judged; when the fuel is in a state of not being easy to combust, the rotating speed of the first pump body 101 is controlled to be reduced, so as to reduce the flow of the lubricating oil; and / or the rotating speed of the second pump body 201 is controlled to be reduced, so as to reduce the flow of the cooling liquid, so that when the fuel is in a state of not being easy to combust, it indicates that the methane combustion at this time is incomplete, and the uncombusted methane is easy to be discharged into the atmosphere, at this time, the application reduces the flow of the cooling liquid and / or the lubricating oil, so as to reduce the cooling amount of the cylinder body, improve the combustion chamber wall surface temperature, reduce the methane wall surface quenching risk, so as to ensure that the methane in the cylinder body can be fully combusted, thereby reducing the methane emission amount.

[0047] The above only describes the preferred embodiments of the application and is not used to limit the application. The application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. An engine control method suitable for an HPDI engine, the HPDI engine comprising a cylinder block and a piston (1) movably arranged on the cylinder block, the HPDI engine comprising a first flow pipeline (100) for connecting with the piston (1), the first flow pipeline (100) being used for feeding lubricating oil to the piston (1), and a first pump body (101) being arranged on the first flow pipeline (100); an outer side of the cylinder block is sleeved with a cylinder water jacket (2), and the HPDI engine further comprises a second flow pipeline (200) for connecting with the cylinder water jacket (2), the second flow pipeline (200) being used for feeding cooling liquid to the cylinder water jacket (2), and a second pump body (201) being arranged on the second flow pipeline (200), characterized in that, The engine control method comprises: During actual operation of the HPDI engine, an actual excess air coefficient λ is obtained; According to the actual excess air coefficient λ, the ease of combustion of the fuel in the cylinder block of the HPDI engine is determined; When the fuel is not easy to combust, the rotational speed of the first pump body (101) is controlled to decrease to reduce the flow of the lubricating oil; and / or the rotational speed of the second pump body (201) is controlled to decrease to reduce the flow of the cooling liquid.

2. The engine control method according to claim 1, characterized by, The method for determining the ease of combustion of the fuel comprises: A predetermined excess air coefficient λ1 is obtained; The size relationship between the actual excess air coefficient λ and the predetermined excess air coefficient λ1 is compared; When the actual excess air coefficient λ is greater than the predetermined excess air coefficient λ1, the rotational speed of the first pump body (101) and / or the rotational speed of the second pump body (201) is controlled to decrease, otherwise, the rotational speed of the first pump body (101) and the rotational speed of the second pump body (201) are maintained unchanged.

3. The engine control method according to claim 2, characterized by, The method for obtaining the predetermined excess air coefficient λ1 comprises: The HPDI engine is controlled to be in a preset operating state, and a plurality of experimental excess air coefficients in the process of the HPDI engine in the preset operating state and the corresponding methane emission amounts under each experimental excess air coefficient are recorded; According to the corresponding relationship between a plurality of experimental excess air coefficients and the methane emission amounts, the excess air coefficient corresponding to the growth rate of the methane emission amount greater than a predetermined value is selected as the predetermined excess air coefficient λ1.

4. The engine control method according to claim 3, characterized by, The method for obtaining the predetermined excess air coefficient λ1 further comprises: A corresponding relationship diagram between the methane emission amount and the experimental excess air coefficient is drawn; An inflection point in the corresponding relationship diagram is selected as the predetermined excess air coefficient λ1; wherein the inflection point of the corresponding relationship diagram is the inflection point of the growth rate of the methane emission amount.

5. The engine control method according to claim 1, characterized by, When the fuel is not easy to combust, the engine control method comprises: The rotational speed of the first pump body (101) is controlled to decrease to a first minimum preset value; and / or, The rotational speed of the second pump body (201) is controlled to decrease to a second minimum preset value.

6. The engine control method according to claim 5, characterized by, The engine control method further comprises: The HPDI engine is controlled to be in a preset operating state; In the process of the preset operating state, the HPDI engine has a plurality of preset operating conditions, and the rotational speed and the torque of the plurality of preset operating conditions are all different, in each preset operating condition, the rotational speed of the first pump body (101) and the rotational speed of the second pump body (201) are gradually decreased until the HPDI engine is subjected to cylinder pulling; In each preset operating condition, a first minimum rotational speed critical value of the first pump body (101) and a second minimum rotational speed critical value of the second pump body (201) when the HPDI engine is subjected to cylinder pulling are recorded; In the actual operation process of the HPDI engine, according to the actual operation condition of the HPDI engine, according to the first minimum preset value corresponding to the first minimum speed critical value of each preset operation condition, the second minimum preset value corresponding to the second minimum speed critical value of each preset operation condition is obtained.

7. The engine control method according to claim 6, characterized by, In the actual operation process of the HPDI engine, after obtaining the first minimum speed critical value and the second minimum speed critical value under the corresponding actual operation condition, the method for obtaining the first minimum preset value and the second minimum preset value further comprises: multiplying the first minimum speed critical value by a first safety coefficient a to obtain the first minimum preset value of the rotation speed of the first pump body (101); multiplying the second minimum speed critical value by a second safety coefficient b to obtain the second minimum preset value of the rotation speed of the second pump body (201); wherein the first safety coefficient a and the second safety coefficient b are both greater than 1.

8. The engine control method according to claim 7, characterized by, The value range of the first safety coefficient a is 1.5 to 2.5; and / or the value range of the second safety coefficient b is 1.5 to 2.

5.

9. A HPDI engine adapted to the engine control method according to any one of claims 1 to 8, characterized in that, The HPDI engine comprises: a cylinder block; a cylinder block water jacket (2) sleeved outside the cylinder block, the HPDI engine further comprising a second flow pipeline (200) connected with the cylinder block water jacket (2), the second flow pipeline (200) being used for passing in cooling liquid, the second flow pipeline (200) being provided with a second pump body (201); a piston (1) movably arranged in the cylinder block, the HPDI engine comprising a first flow pipeline (100) connected with the piston (1), the first flow pipeline (100) being used for passing in engine oil, the first flow pipeline (100) being provided with a first pump body (101); wherein the inner wall surface of the piston (1) is provided with a first thermal insulation coating (102).

10. The HPDI engine of claim 9, wherein, The cylinder block comprises a cylinder block main body and a cylinder head part connected with each other, the cylinder head part and the piston (1) being arranged at two ends of the cylinder block main body respectively, the cylinder block water jacket (2) comprising a cylinder head water jacket (21) and a main body water jacket (20), the cylinder head water jacket (21) being sleeved on the cylinder head, and the main body water jacket (20) being sleeved on the cylinder block main body; wherein the side wall surface of the cylinder head water jacket (21) close to the piston (1) is provided with a second thermal insulation coating (202).

Images