阅读说明：本技术 发动机冷却系统的控制方法及发动机冷却系统 (Control method of engine cooling system and engine cooling system ) 是由 韩俊楠 侯福建 柳国立 孟繁臣 王峰 刘爽 于 2021-08-09 设计创作，主要内容包括：本申请涉及一种发动机冷却系统的控制方法,包括获取发动机在不同转速区间内的进气量值,并计算得到平均有效压力值,确定与之对应的节温器开启温度值；并判断在同一转速区间内发动机的冷却液液压值与预设冷却液液压值的偏差的偏差的变化率是否超过第一预设变化率阈值,若超过,则以第一幅值为步幅降低节温器开启温度值,直至该变化率低于第二预设变化率阈值。上述发动机冷却系统的控制方法,使节温器开启温度值由发动机的进气量值与冷却液液压值两种参数确定,且由于冷却液的液压值与冷却液的流量相关,避免因冷却液的流量偏离预设而导致冷却液局部沸腾强度过高,使冷却液局部沸腾得到有效的控制。(The application relates to a control method of an engine cooling system, which comprises the steps of obtaining air intake values of an engine in different rotating speed intervals, calculating to obtain an average effective pressure value, and determining a thermostat starting temperature value corresponding to the average effective pressure value; and judging whether the change rate of the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval exceeds a first preset change rate threshold value or not, and if so, reducing the starting temperature value of the thermostat by taking the first amplitude as a step until the change rate is lower than a second preset change rate threshold value. According to the control method of the engine cooling system, the thermostat starting temperature value is determined by two parameters, namely the air intake value of the engine and the hydraulic value of the cooling liquid, and the hydraulic value of the cooling liquid is related to the flow of the cooling liquid, so that the phenomenon that the local boiling strength of the cooling liquid is too high due to deviation of the flow of the cooling liquid from the preset value is avoided, and the local boiling of the cooling liquid is effectively controlled.)

1. A control method of an engine cooling system, characterized by comprising:

acquiring the air intake values of the engine in different rotating speed intervals, and calculating to obtain the average effective pressure values of the engine in the different rotating speed intervals;

determining thermostat starting temperature values in different rotating speed intervals corresponding to the average effective pressure values of the engine in different rotating speed intervals;

the method comprises the steps of obtaining the hydraulic values of cooling liquid of an engine in different rotating speed intervals, and judging whether the change rate of the deviation of the hydraulic value of the cooling liquid of the engine and a preset hydraulic value of the cooling liquid in the same rotating speed interval exceeds a first preset change rate threshold value or not;

if the change rate of the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval exceeds a first preset change rate threshold value, reducing the starting temperature value of the thermostat by taking a first amplitude value as a step until the change rate of the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval is lower than a second preset change rate threshold value;

wherein the first preset rate of change threshold is greater than the second preset rate of change threshold.

2. The method for controlling the engine cooling system according to claim 1, wherein the obtaining the intake air amount value of the engine in different speed intervals and calculating the average effective pressure value of the engine in the different speed intervals specifically comprises:

determining torque values of the engine in different rotating speed intervals according to the air intake value of the engine in the different rotating speed intervals;

calculating the average effective pressure value BMEP of the engine in different speed intervals according to the formula BMEP tau multiplied by T divided by 31.83 divided by V;

wherein tau is the stroke number of the engine, T is the torque value of the engine, and V is the displacement of the engine.

3. The control method of an engine cooling system according to claim 1, characterized in that the first preset rate-of-change threshold is 5%/second;

the second predetermined rate of change threshold is 2%/second.

4. The control method of the engine cooling system according to claim 1, characterized by further comprising:

if the change rate of the deviation between the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval is not changed in the first preset time period, the rotating speed of the fan is increased by taking the second amplitude as a step until the change rate of the deviation between the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval is lower than a second preset change rate threshold value.

5. The control method of the engine cooling system according to claim 4, characterized in that the first preset time period is 5 seconds;

the second amplitude is 100 rpm.

6. The control method of the engine cooling system according to claim 1, characterized by further comprising:

and if the change rate of the deviation between the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval is not changed in a second preset time period, determining that the thermostat is in fault, and controlling the rotating speed and the load of the engine to be reduced.

7. The control method of the engine cooling system according to claim 6, characterized in that the second preset time period is 15 s.

8. The control method of the engine cooling system according to claim 1, characterized by further comprising:

the method comprises the steps of obtaining the hydraulic values of cooling liquid of an engine in different rotating speed intervals, and judging whether the deviation between the hydraulic value of the cooling liquid of the engine and a preset hydraulic value of the cooling liquid in the same rotating speed interval exceeds a first preset deviation threshold value or not;

and if the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval exceeds a first preset deviation threshold value, determining that the cooling system is in fault.

9. The method for controlling the engine cooling system according to claim 8, wherein the determining that the cooling system is faulty if the deviation between the hydraulic value of the coolant of the engine and the preset hydraulic value of the coolant in the same rotation speed interval exceeds a first preset deviation threshold value specifically comprises:

if the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the first rotating speed interval exceeds a first preset deviation threshold value, determining that the cooling liquid pressure sensor has a fault and the cooling water pump has a fault;

if the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the second rotating speed interval exceeds a first preset deviation threshold value, determining that devices in the cooling system except the cooling liquid pressure sensor and the cooling water pump are in failure;

and the rotating speed value of the engine in the first rotating speed interval is smaller than the rotating speed value of the engine in the second rotating speed interval.

10. An engine cooling system, the engine including an engine block, an engine head, and an engine intake, the engine cooling system comprising:

the cooling water pump is connected with the engine cylinder body;

a radiator connected with the cooling water pump and the engine cylinder block;

a fan provided between the radiator and the engine block;

the thermostat is arranged at an outlet of the engine cylinder cover;

the engine cooling system further includes:

the cooling liquid temperature sensor and the cooling liquid pressure sensor are arranged between the engine cylinder cover and the thermostat;

the engine rotating speed sensor and the engine air inflow sensor are arranged in the engine air inlet pipe;

and the electronic control unit is electrically connected with the cooling liquid temperature sensor, the cooling liquid pressure sensor, the engine rotating speed sensor, the engine air inflow sensor, the fan and the thermostat.

Technical Field

The application relates to the technical field of automobiles, in particular to a control method of an engine cooling system and the engine cooling system.

Background

At present, the national six natural gas engine mainly adopts equivalent combustion, EGR and three-way catalytic technology, so that a large amount of heat generated in the combustion process is transferred into cooling liquid. In the related art, the engine is prevented from overheating by acquiring the water temperature value of the engine coolant.

However, the current engine cooling system cannot effectively control the local boiling of the cooling liquid.

Disclosure of Invention

In view of the above, it is necessary to provide a method for controlling an engine cooling system and an engine cooling system that can effectively control local boiling of coolant, in order to solve the problem of local boiling of coolant.

According to an aspect of the present application, there is provided a control method of an engine cooling system, including:

acquiring the air intake values of the engine in different rotating speed intervals, and calculating to obtain the average effective pressure values of the engine in the different rotating speed intervals;

determining thermostat starting temperature values in different rotating speed intervals corresponding to the average effective pressure values of the engine in different rotating speed intervals;

the method comprises the steps of obtaining the hydraulic values of cooling liquid of an engine in different rotating speed intervals, and judging whether the change rate of the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval exceeds a first preset change rate threshold value or not;

if the change rate of the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval exceeds a first preset change rate threshold value, reducing the starting temperature value of the thermostat by taking a first amplitude value as a step until the change rate of the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval is lower than a second preset change rate threshold value;

wherein the first preset rate of change threshold is greater than the second preset rate of change threshold.

According to the control method of the engine cooling system, the opening temperature values of the electronic thermostat corresponding to different working conditions of the engine are set according to the air intake values of the engine in different rotating speed intervals, when the change rate of the deviation between the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in different rotating speed intervals exceeds a first preset change rate threshold value, the opening temperature value of the thermostat is reduced, the opening temperature value of the thermostat is determined by two parameters of the air intake values and the hydraulic value of the cooling liquid of the engine, and the hydraulic value of the cooling liquid is related to the flow of the cooling liquid, so that the phenomenon that the local boiling strength of the cooling liquid is too high due to deviation of the flow of the cooling liquid from the preset value is avoided, and the local boiling of the cooling liquid is effectively controlled.

In one embodiment, the obtaining the intake air quantity values of the engine in different rotation speed intervals, and calculating the average effective pressure value of the engine in the different rotation speed intervals specifically includes:

determining torque values of the engine in different rotating speed intervals according to the air intake value of the engine in the different rotating speed intervals;

calculating the average effective pressure value BMEP of the engine in different speed intervals according to the formula BMEP tau multiplied by T divided by 31.83 divided by V;

wherein tau is the stroke number of the engine, T is the torque value of the engine, and V is the displacement of the engine.

In one embodiment, the first predetermined rate of change threshold is 5%/second;

the second predetermined rate of change threshold is 2%/second.

In one embodiment, the method further comprises:

if the change rate of the deviation between the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval is not changed in the first preset time period, the rotating speed of the fan is increased by taking the second amplitude as a step until the change rate of the deviation between the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval is lower than a second preset change rate threshold value.

In one embodiment, the first preset time period is 5 seconds;

the second amplitude is 100 rpm.

In one embodiment, the method further comprises:

and if the change rate of the deviation between the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval is not changed in a second preset time period, determining that the thermostat is in fault, and controlling the rotating speed and the load of the engine to be reduced.

In one embodiment, the second predetermined time period is 15 s.

In one embodiment, the method further comprises:

the method comprises the steps of obtaining the hydraulic values of cooling liquid of an engine in different rotating speed intervals, and judging whether the deviation between the hydraulic value of the cooling liquid of the engine and a preset hydraulic value of the cooling liquid in the same rotating speed interval exceeds a first preset deviation threshold value or not;

and if the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval exceeds a first preset deviation threshold value, determining that the cooling system is in fault.

In one embodiment, the determining that the cooling system has a fault if the deviation between the hydraulic value of the coolant of the engine and the preset hydraulic value of the coolant in the same rotation speed interval exceeds a first preset deviation threshold specifically includes:

if the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the first rotating speed interval exceeds a first preset deviation threshold value, determining that the cooling liquid pressure sensor has a fault and the cooling water pump has a fault;

if the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the second rotating speed interval exceeds a first preset deviation threshold value, determining that devices in the cooling system except the cooling liquid pressure sensor and the cooling water pump are in failure;

and the rotating speed value of the engine in the first rotating speed interval is smaller than the rotating speed value of the engine in the second rotating speed interval.

According to another aspect of the present application, there is provided an engine cooling system, the engine including an engine block, an engine head, and an engine intake duct, the engine cooling system comprising:

the cooling water pump is connected with the engine cylinder body;

a radiator connected with the cooling water pump and the engine cylinder block;

a fan provided between the radiator and the engine block;

the thermostat is arranged at an outlet of the engine cylinder cover;

the engine cooling system further includes:

the cooling liquid temperature sensor and the cooling liquid pressure sensor are arranged between the engine cylinder cover and the thermostat;

the engine rotating speed sensor and the engine air inflow sensor are arranged in the engine air inlet pipe;

and the electronic control unit is electrically connected with the cooling liquid temperature sensor, the cooling liquid pressure sensor, the engine rotating speed sensor, the engine air inflow sensor, the fan and the thermostat.

Drawings

FIG. 1 is a schematic illustration of an engine cooling system according to an embodiment of the present application;

FIG. 2 is a block flow diagram of a method of controlling an engine cooling system according to an embodiment of the present application;

FIG. 3 is a graph illustrating engine speed, mean effective pressure, and thermostat opening temperature in accordance with an embodiment of the present disclosure.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of embodiments in many different forms than those described herein and that modifications may be made by one skilled in the art without departing from the spirit and scope of the application and it is therefore not intended to be limited to the specific embodiments disclosed below.

In the description of the present application, it is to be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present application and for simplicity in description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the present application.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In this application, unless expressly stated or limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can include, for example, fixed connections, removable connections, or integral parts; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through intervening media. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

At present, the national six natural gas engine mainly adopts equivalent combustion, EGR and three-way catalytic technical routes, so that a large amount of heat is generated in the combustion process and is transmitted into cooling liquid, and then is discharged into the atmosphere through a heat dissipation system. Because the heat dissipation capacity of the engine is large, after the engine is started, the coolant has a local boiling phenomenon in the process that the temperature of the coolant is gradually increased from the ambient temperature. When the temperature of the cooling liquid is between 90 and 95 ℃, the local boiling of the cooling liquid enables a large amount of heat exchange between the cooling liquid and the engine cylinder cover, and the temperature of the cylinder cover is in a normal temperature range, which is an ideal working condition of the engine cooling system. However, the boiled coolant contains a large amount of bubbles, which causes cavitation of the water pump and further affects the flow rate of the water pump, and as the flow rate is reduced, the boiling is further intensified to form vicious circle, which causes overheating and cracking of components such as an engine cylinder cover.

In the related art, the temperature value of the cooling liquid is obtained, and the starting temperature of the thermostat is controlled according to the difference value between the actual temperature value of the cooling liquid and the preset temperature value of the cooling liquid, but the working condition of the engine is continuously changed in the temperature rising process, and the temperature of the cooling liquid at different positions cannot be measured due to the number limit value of the temperature sensors, so that the calculation result is inaccurate, and the local boiling of the cooling liquid cannot be effectively controlled.

Therefore, it is necessary to provide a method for controlling an engine cooling system and an engine cooling system capable of effectively controlling the local boiling of the coolant.

FIG. 1 is a schematic illustration of an engine cooling system according to an embodiment of the present application.

Referring to fig. 1, the engine includes an engine cylinder block 1, an engine cylinder head 2 and an engine intake pipe, and in an embodiment of the present application, the engine cooling system includes a cooling water pump 3, a radiator 4, a fan 5, a thermostat 6, a coolant temperature sensor 7, a coolant pressure sensor 8, an engine speed sensor 9, an engine intake air amount sensor 10 and an electronic control unit 11.

The cooling water pump 3 is connected to the engine block 1, and is configured to pressurize the coolant so that the coolant circulates in the engine cooling system. The radiator 4 is connected to the cooling water pump 3 and the engine block 1, and the coolant flows in the radiator 4 and radiates heat to the air. The fan 5 is provided between the radiator 4 and the engine block 1 for assisting the radiator 4 in radiating heat. The thermostat 6 is arranged at the outlet of the engine cylinder cover 2 and used for changing the flow path of the cooling liquid, and when the thermostat 6 is not opened, the cooling liquid returns to the engine through the cooling water pump 3 to form a small circulation; when the thermostat 6 is opened, the coolant flows through the radiator 4 and then returns to the engine through the water pump, and a large circulation is formed.

The cooling liquid temperature sensor 7 and the cooling liquid pressure sensor 8 are arranged between the engine cylinder cover 2 and the thermostat 6, the cooling liquid temperature sensor 7 is used for collecting cooling liquid temperature values, and the cooling liquid pressure sensor 8 is used for collecting cooling liquid hydraulic values of the engine in different rotating speed intervals; the engine speed sensor 9 and the engine air inflow sensor 10 are both arranged in an engine air inlet pipe, the engine speed sensor 9 is used for collecting the rotating speed value of the engine, and the engine air inflow sensor 10 is used for collecting the air inflow value of the engine in different rotating speed intervals.

The electronic control unit 11 is electrically connected with the coolant temperature sensor 7, the coolant pressure sensor 8, the engine speed sensor 9, the engine air intake sensor 10, the fan 5 and the thermostat 6. It should be noted that the electronic control unit 11 obtains the temperature value of the coolant through the coolant temperature sensor 7, and determines whether the temperature value of the coolant is greater than the thermostat starting temperature value, and when the temperature value of the coolant is greater than the thermostat starting temperature value, the electronic control unit 11 controls the thermostat 6 to start.

FIG. 2 is a block flow diagram of a method of controlling an engine cooling system according to an embodiment of the present application.

Referring to fig. 2, the present application also provides a control method of an engine cooling system, including:

s110: and acquiring the air intake value of the engine in different rotating speed intervals, and calculating to obtain the average effective pressure value of the engine in different rotating speed intervals.

Specifically, the engine speed sensor 9 collects the engine speed value, and the engine air intake quantity sensor 10 collects the engine air intake quantity value in different speed intervals. The electronic control unit 11 is electrically connected with the engine speed sensor 9 and the engine air inflow sensor 10 respectively to obtain a speed value of the engine and an air inflow value of the engine, and calculate to obtain average effective pressure values of the engine in different speed intervals.

In some embodiments, step S110 includes:

s111: and determining the torque value of the engine in different rotating speed intervals according to the air intake value of the engine in different rotating speed intervals.

It can be understood that the torque value of the engine is controlled by the air intake value of the engine, the relationship between the two is related to the parameters and the operation conditions of the engine, the torque values corresponding to the air intake values of different engines in different rotation speed intervals are determined through experiments, so as to form a corresponding table of the air intake values and the torque values of the engine in different rotation speed intervals, and the corresponding table is stored in the electronic control unit 11 of the engine.

S112: calculating the average effective pressure value BMEP of the engine in different speed intervals according to the formula BMEP tau multiplied by T divided by 31.83 divided by V; wherein tau is the stroke number of the engine, T is the torque value of the engine, and V is the displacement of the engine.

For example, in one embodiment, the engine is a four-stroke engine, and the displacement of the engine is 1.598L.

S120: and determining the thermostat starting temperature values in different rotating speed intervals corresponding to the average effective pressure values of the engine in different rotating speed intervals.

And the thermostat opening temperature value and the rotating speed value and the average effective pressure value of the engine have a corresponding relation. It can be understood that, because the average effective pressure refers to the effective work emitted by the unit working volume of the cylinder of the engine, the larger the average effective pressure is, the stronger the work-doing capability of the engine is; the rotating speed of the engine is related to the number of times of doing work in unit time, namely the effective power of the engine is changed along with the different rotating speeds, so that the rotating speed value and the average effective pressure value of the engine are set as parameters for determining the working condition of the engine, and the corresponding thermostat starting temperature value is determined, so that the thermostat 6 can be started at a proper temperature, the circulating range of the cooling liquid is changed, and the overheating or overcooling of the engine caused by too late or too early starting of the thermostat 6 is prevented. For example, the greater the engine speed value and the greater the average effective pressure value, the greater the engine work at that time, the greater the amount of heat dissipated, and the more likely the coolant will be subjected to vigorous partial boiling, so the lower the thermostat opening temperature value is in order to prevent overheating of the engine head 2.

FIG. 3 is a graph illustrating engine speed, mean effective pressure, and thermostat opening temperature in accordance with an embodiment of the present disclosure.

In the specific embodiment, as shown in fig. 3, when the engine speed is 600 rpm to 1400 rpm and the average effective pressure value is 0 to 10bar, the thermostat starting temperature value is 100 ℃; when the rotating speed of the engine is 600-1400 rpm and the average effective pressure value is 10-14 bar, the starting temperature value of the thermostat is 95 ℃; when the rotating speed of the engine is 1400-1800 rpm and the average effective pressure value is 0-14 bar, the starting temperature value of the thermostat is 95 ℃; and when the working condition of the engine is not in the interval, the starting temperature value of the thermostat is 85 ℃.

S130: the method comprises the steps of obtaining the hydraulic values of the cooling liquid of the engine in different rotating speed intervals, and judging whether the change rate of the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval exceeds a first preset change rate threshold value or not.

Specifically, the hydraulic values of the cooling liquid of the engine in different rotating speed intervals are collected through the cooling liquid pressure sensor 8. The electronic control unit 11 is electrically connected to the coolant pressure sensor 8 to obtain a coolant hydraulic pressure value, calculate a change rate of a deviation between the coolant hydraulic pressure value of the engine and a preset coolant hydraulic pressure value in the same rotational speed interval, and determine whether the calculated change rate of the deviation exceeds a first preset change rate threshold.

S140: if the change rate of the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval exceeds a first preset change rate threshold value, reducing the starting temperature value of the thermostat by taking a first amplitude value as a step until the change rate of the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval is lower than a second preset change rate threshold value; wherein the first preset rate of change threshold is greater than the second preset rate of change threshold.

It can be understood that, because the coolant liquid hydraulic pressure value is related to the flow of the coolant liquid, and the flow rate of the coolant liquid, that is, the flow velocity, is related to the heat exchange efficiency between the coolant liquid and the engine cylinder head 2, when the coolant liquid hydraulic pressure value and the preset coolant liquid hydraulic pressure value have a larger variation rate, the larger variation rate of the deviation of the coolant liquid flow velocity and the preset flow velocity is represented, and therefore the thermostat opening temperature value is reduced by taking the first amplitude as a step, so as to prevent the thermostat 6 from being opened too late, and avoid that the coolant liquid flow rate caused by high local boiling strength is too small to cause further boiling.

Specifically, the first predetermined rate of change threshold is 5%/second and the second predetermined rate of change threshold is 2%/second. Further, in one embodiment, the thermostat opening temperature value is changed in steps of decreasing by 10 ℃ every 3 seconds.

In some embodiments of the present application, the control method of the engine cooling system further comprises:

s150: if the change rate of the deviation between the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval is not changed in the first preset time period, the rotating speed of the fan is increased by taking the second amplitude as a step until the change rate of the deviation between the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval is lower than a second preset change rate threshold value.

It will be appreciated that the thermal condition of the engine changes due to changes in the engine ambient conditions and operating conditions, and the intensity of cooling of the engine is adjusted by changing the speed of the engine's fan 5. When the change rate of the deviation between the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval is not changed in the first preset time period, the rotating speed of the fan 5 blowing air to the radiator 4 is increased, the cooling air volume is increased, the heat dissipation capacity of the radiator 4 is improved, the cooling of the cooling liquid is accelerated, the local boiling strength of the cooling liquid is reduced, bubbles generated by the boiling of the cooling liquid are reduced, and the flow rate of the cooling liquid and the corresponding hydraulic value are in an expected range.

Specifically, the first preset time period is 5 seconds, and the second amplitude is 100 rpm.

In some embodiments of the present application, the control method of the engine cooling system further comprises:

s160: and if the change rate of the deviation between the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval is not changed in a second preset time period, determining that the thermostat is in fault, and controlling the rotating speed and the load of the engine to be reduced.

It can be understood that the duration of the second preset time period is longer than the duration of the first preset time period, and when the variation rate of the deviation between the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval is not changed in the second preset time period, the increase of the rotating speed of the fan 5 still does not effectively improve the boiling condition of the cooling liquid, so that the fault of the thermostat 6 is determined, the rotating speed and the load of the engine are controlled to be reduced, and the workpiece damage caused by the overheating of the engine is avoided.

In an embodiment, the second preset time period is 15 s.

In some embodiments, the method of controlling an engine cooling system further comprises:

s210: the method comprises the steps of obtaining the hydraulic values of the cooling liquid of the engine in different rotating speed intervals, and judging whether the deviation between the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval exceeds a first preset deviation threshold value.

Specifically, the first preset deviation threshold is 30%.

S220: and if the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the same rotating speed interval exceeds a first preset deviation threshold value, determining that the cooling system is in fault.

It should be noted that, in the same rotation speed interval, the deviation between the hydraulic value of the coolant of the engine and the preset hydraulic value of the coolant exceeds the first preset deviation threshold value, which indicates that the hydraulic value of the coolant deviates abnormally from the preset hydraulic value of the coolant, and the cooling system has a fault.

Further, if the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the first rotating speed interval exceeds a first preset deviation threshold value, determining that the cooling liquid pressure sensor 8 has a fault and the cooling water pump 3 has a fault; if the deviation of the hydraulic value of the cooling liquid of the engine and the preset hydraulic value of the cooling liquid in the second rotating speed interval exceeds a first preset deviation threshold value, determining that devices in the cooling system except the cooling liquid pressure sensor 8 and the cooling water pump 3 are in failure; and the rotating speed value of the engine in the first rotating speed interval is smaller than the rotating speed value of the engine in the second rotating speed interval.

Specifically, the first rotation speed interval is 600 rpm to 800 rpm, and the second rotation speed interval is greater than or equal to 800 rpm.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.