An engine water outlet pressure overheat protection correction method and system

Abstract

The present invention provides an engine water outlet pressure overheat protection correction method and system, including: obtaining the water outlet pressure value and the current water outlet temperature of the engine water outlet pipe; judging whether the engine water circuit is depressurized based on the water outlet pressure value; if the engine water circuit is depressurized, obtaining the boiling point of the coolant at the current pressure based on the corresponding relationship between the water outlet pressure value and the coolant temperature; and determining the engine overheat protection strategy based on the current water outlet temperature and the boiling point of the coolant at the current pressure. The present invention judges the boiling point of the coolant at the current pressure through the water outlet pressure. After the water circuit is depressurized, it ensures that the water temperature overheat protection can take effect in time, protecting the engine from damage due to overheating.

Description

Technical Field

[0001] The invention belongs to the technical field of engine overheat protection correction, and in particular relates to an engine water outlet pressure overheat protection correction method and system. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Vehicles will be operated in areas with different altitudes, and the boiling point of the coolant will decrease as the altitude increases. When the expansion tank pressure cap is well sealed, as the outlet water temperature gradually rises, part of the water will vaporize, causing the pressure in the water circuit to gradually increase, and the boiling point of the coolant will also rise accordingly. Figure 1 During the thermal balance test, the engine runs at the rated point. As the running time increases, the outlet water temperature and outlet water pressure will gradually increase and tend to stabilize. If the expansion tank pressure cap seal fails, the pressure in the engine water chamber will decrease. The boiling point of -45℃ coolant is 109℃ under standard atmospheric pressure. Its boiling point is 92℃ under the extreme environment of 5000 meters above sea level and 0.54 atmospheres. Taking the H series engine as an example, if the coolant temperature is too high at this time, the ECU will still execute according to the overheating protection logic of the plain state. The torque will be gradually limited only when the temperature exceeds 115℃, and the engine is at risk of overheating.

[0004] Problems caused by engine overheating include:

[0005] (1) Reduce the charging efficiency and reduce the engine power;

[0006] (2) The tendency of deflagration increases, causing premature damage to parts due to additional impact loads;

[0007] (3) The normal clearance of moving parts is destroyed, movement is blocked, wear is aggravated, and even damage occurs;

[0008] (4) The lubrication condition deteriorates, exacerbating the friction and wear of parts;

[0009] (5) The mechanical properties of parts are reduced, resulting in deformation or damage. Summary of the invention

[0010] In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a method and system for correcting engine outlet water pressure overheat protection.

[0011] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0012] A first aspect of the present invention provides an engine outlet water pressure overheat protection correction method, comprising:

[0013] Obtain the water outlet pressure value and the current water outlet temperature of the engine's water outlet pipe;

[0014] Based on the water outlet pressure value, determine whether the engine's water circuit is depressurized;

[0015] If the engine's water circuit is depressurized, based on the corresponding relationship between the water outlet pressure value and the coolant temperature, obtain the boiling point of the coolant at the current pressure;

[0016] Determine the engine overheat protection strategy based on the current water outlet temperature and the boiling point of the coolant at the current pressure.

[0017] The second aspect of the present invention provides an engine water outlet pressure overheat protection correction system, including:

[0018] A pressure sensor for obtaining the water outlet pressure value and the current water outlet temperature of the engine's water outlet pipe;

[0019] A temperature sensor for obtaining the current water outlet temperature;

[0020] A control device for determining whether the engine's water circuit is depressurized based on the water outlet pressure value;

[0021] If the engine's water circuit is depressurized, based on the corresponding relationship between the water outlet pressure value and the coolant temperature, obtain the boiling point of the coolant at the current pressure;

[0022] Determine the engine overheat protection strategy based on the current water outlet temperature and the boiling point of the coolant at the current pressure.

[0023] The above one or more technical solutions have the following beneficial effects:

[0024] (1) The present invention adds a pressure sensor in front of the thermostat of the engine's water outlet pipe to detect the pressure of the circulating water circuit. It adds the correction of the water temperature overheat protection based on the pressure of the circulating water circuit to ensure that the engine can be normally protected from overheating after the water circuit is depressurized.

[0025] (2) The present invention determines the boiling point of the coolant at the current pressure through the water outlet pressure. When the water circuit is depressurized, it ensures that the water temperature overheat protection can take effect in time to protect the engine from being damaged due to overheating.

[0026] The advantages of the additional aspects of the present invention will be partially given in the following description, partially will become obvious from the following description, or will be understood through the practice of the present invention. Description of the Drawings

[0027] The specification drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0028] Figure 1 It is the correspondence between the temperature and pressure of the coolant;

[0029] Figure 2 It is the flowchart of a method for correcting overheat protection of the engine outlet water pressure in the first embodiment;

[0030] Figure 3 It is the correspondence between the outlet water temperature and the injection quantity correction coefficient;

[0031] Figure 4 During the heat balance test, when the engine is operating at the rated point condition, it is the correspondence between the outlet water temperature and the outlet water pressure;

[0032] Figure 5 It is the correspondence between the outlet water pressure and the thermostat fan opening temperature in the first embodiment;

[0033] Figure 6 It is the correspondence between the outlet water pressure and the outlet water temperature correction coefficient in the first embodiment;

[0034] Figure 7 It is the correspondence between the outlet water temperature and the outlet water pressure and the overheat protection coefficient in the first embodiment. Detailed implementation manners

[0035] Embodiment 1

[0036] Term explanation: When a liquid boils, the saturated vapor pressure in the bubbles formed inside it must be equal to the pressure applied from the outside, and only then can the bubbles grow and rise. Therefore, the boiling point is also the temperature at which the saturated vapor pressure of the liquid is equal to the external pressure. The boiling point of a liquid is related to the external pressure. When the pressure on the liquid increases, its boiling point rises; when the pressure decreases, the boiling point decreases. For example, the steam pressure in a steam boiler is about dozens of atmospheres, and the boiling point of the water in the boiler can be above 200 °C. Another example is that when cooking rice on a high mountain, the water boils easily, but the rice is not easy to cook. This is because the atmospheric pressure decreases with the increase in altitude, and the boiling point of water also gradually decreases with the increase in altitude. (At an altitude of 1900 meters, the atmospheric pressure is about 79800 Pa (600 mmHg), and the boiling point of water is 93.5 °C);

[0037] Such as Figure 2 As shown, this embodiment discloses a method for correcting overheat protection of the engine outlet water pressure, including:

[0038] Step S1, obtaining the outlet water pressure value of the engine outlet pipe and the current outlet water temperature;

[0039] Step S2, based on the outlet water pressure value, determining whether the engine water circuit is depressurized;

[0040] Step S3: If the engine water circuit loses pressure, based on the correspondence between the outlet water pressure value and the coolant temperature, obtain the boiling point of the coolant at the current pressure;

[0041] Step S4: Determine the engine overheat protection strategy based on the current outlet water temperature and the boiling point of the coolant at the current pressure;

[0042] Step S5: If the engine water circuit does not lose pressure, the control device controls the engine based on the original temperature overheat protection strategy.

[0043] In step S1, based on the pressure sensor and temperature sensor installed on the engine outlet pipe, obtain the outlet water pressure value and outlet water temperature of the circulating water circuit. The ECU (Electronic Control Unit) obtains the pressure value in the circulating water circuit through the outlet water pressure sensor, and then makes a determination on the outlet water pressure.

[0044] In step S2, the steps for determining whether the engine water circuit loses pressure include:

[0045] If the current outlet water pressure value is less than the pressure value corresponding to the lowest temperature at which the original overheat protection strategy takes effect, then the engine water circuit loses pressure;

[0046] If the pressure value of the current circulating water circuit is greater than or equal to the pressure value corresponding to the lowest temperature at which the original overheat protection strategy takes effect, then the engine water circuit does not lose pressure;

[0047] Among them, the lowest temperature at which the original overheat protection strategy takes effect is 115°C, and the pressure value corresponding to the lowest temperature at which the original overheat protection takes effect is one standard atmosphere, which is 1013.25 hPa;

[0048] Specifically, as Figure 3 shown, taking the original overheat protection strategy of the H series diesel engine as an example, the overheat protection of the water temperature of the H series diesel engine mostly starts to limit the fuel quantity above 115°C. The correction coefficient corresponding to 115°C is 1, the correction coefficient corresponding to 118°C is 0.5, the correction coefficient corresponding to 121°C is 0.19, and when it reaches 125°C, the correction coefficient is 0, and the engine will completely stop fuel supply;

[0049] In step S3, based on the heat balance test, obtain the correspondence between the outlet water pressure value of the engine and the coolant temperature; based on the correspondence between the outlet water pressure value and the coolant temperature, obtain the boiling point of the coolant at the current pressure;

[0050] As Figure 4 shown, for -45°C coolant under standard atmospheric pressure, its boiling point is 109°C, and in the extreme environment of 5000 meters above sea level and 0.54 atmospheric pressure, its boiling point is 92°C.

[0051] In step S4, an engine overheat protection strategy is determined based on the current outlet water temperature and the boiling point of the coolant at the current pressure, including:

[0052] S401. Determine whether the current outlet water temperature is greater than the boiling point of the coolant at the current pressure;

[0053] S402. If the current outlet water temperature is greater than the boiling point of the corresponding coolant at the current pressure, correct the current outlet water temperature based on the outlet water temperature correction coefficient so that the corrected water temperature reaches the minimum value for the operation of the original temperature overheat protection strategy, and select the original temperature overheat protection strategy to control the engine based on the corrected water temperature;

[0054] Among them, based on the corresponding relationship between the outlet water pressure and the outlet water temperature correction coefficient, determine the outlet water temperature correction coefficient at the current pressure; multiply the outlet water temperature correction coefficient at the current pressure by the current outlet water temperature to obtain the corrected water temperature;

[0055] As Figure 5 shown, when the outlet water pressure is 1500 hPa, the outlet water temperature correction coefficient is 1; when the outlet water pressure is 1200 hPa, the outlet water temperature correction coefficient is 1.2; when the outlet water pressure is 1000 hPa, the outlet water temperature correction coefficient is 1.4; when the outlet water pressure is 800 hPa, the outlet water temperature correction coefficient is 1.6; when the outlet water pressure is 600 hPa, the outlet water temperature correction coefficient is 1.8; when the outlet water pressure is 500 hPa, the outlet water temperature correction coefficient is 2;

[0056] Among them, in this embodiment, when any outlet water pressure is known, the corresponding outlet water temperature correction coefficient at any outlet water pressure can be calculated by using the interpolation method based on the given corresponding relationship between the outlet water pressure and the outlet water temperature correction coefficient in this embodiment; for example, when the outlet water pressure is 900 hPa, the outlet water temperature correction coefficient at this time is

[0057] If the current water temperature is higher than the boiling point at the corresponding pressure, the present invention corrects the water temperature in the higher direction. The lower the outlet water pressure, the higher the corrected water temperature, ensuring that the corrected water temperature is higher than 115 degrees, which can play a role in restricting the fuel quantity to protect the engine from damage due to overheating; at the same time, an error message should be given to prompt the driver that the circulating water circuit seal fails and immediate maintenance is required.

[0058] S403. If the current outlet water temperature is less than or equal to the boiling point of the coolant at the current pressure, determine whether the current outlet water temperature is less than the opening temperature of the thermostat;

[0059] Among them, the opening temperature of the thermostat is generally 70 degrees to 80 degrees, and the specific value can be set according to the actual situation;

[0060] S404. If the current outlet water temperature is less than the opening temperature of the thermostat, there is no overheating risk for the engine.

[0061] The circulation mode of the engine cooling system is divided into a small circulation and a large circulation, and the two circulation modes are switched by the opening and closing of the thermostat.

[0062] When the engine's thermostat is in the closed state and the engine is just started, the cooling system enters the small circulation mode. In the small circulation mode, the coolant only circulates in the water channels inside the engine, and the amount of coolant participating in the circulation is also less.

[0063] When the water temperature gradually rises, under the action of the temperature, the thermostat opens, and the cooling system enters the large circulation mode. In the large circulation mode, the coolant will flow through the radiator outside the engine, that is, the radiator of the water tank, and with the help of the cooling fan, the excess heat is "released" to achieve the effect of stabilizing the water temperature.

[0064] S405. If the current outlet water temperature is greater than or equal to the opening temperature of the thermostat, correct the opening temperature of the cooling fan, that is, reduce the opening temperature of the cooling fan and turn on the fan in advance for heat dissipation to avoid engine overheating.

[0065] Among them, according to the current outlet water pressure, select the corresponding correction coefficient for the opening temperature of the cooling fan to correct the opening temperature of the cooling fan.

[0066] The corresponding relationship between the outlet water pressure and the correction coefficient of the opening temperature of the cooling fan is as Figure 5 shown. When the outlet water pressure is 500 hPa, the correction coefficient of the opening temperature of the cooling fan is 0.5; when the outlet water pressure is 600 hPa, the correction coefficient of the opening temperature of the cooling fan is 0.6; when the outlet water pressure is 700 hPa, the correction coefficient of the opening temperature of the cooling fan is 0.7; if the outlet water pressure is greater than or equal to 1010 hPa, the correction coefficient of the opening temperature of the cooling fan is 1.

[0067] As Figure 7 shown, the overheat protection cur of the outlet water temperature can also be changed to the overheat protection map, with the outlet water temperature on the abscissa, the outlet water pressure on the ordinate, and the content being the correction coefficient:

[0068] The specific steps are as follows:

[0069] The ECU obtains the water temperature and pressure values of the water circuit through the outlet water temperature and pressure sensors respectively.

[0070] The ECU obtains the overheat protection coefficient by looking up the table based on the obtained outlet water temperature and outlet water pressure.

[0071] The ECU multiplies the obtained overheat protection coefficient by the fuel quantity of the external characteristic at the corresponding rotational speed to limit the fuel quantity of the external characteristic, reduce the fuel supply quantity per cycle, lower the engine heat load, and achieve the effect of reducing the outlet water temperature, avoiding overheating failure of the engine.

[0072] Among them, the corresponding relationship between the outlet water temperature and the outlet water pressure and the overheat protection coefficient can be obtained through experiments.

[0073] Embodiment 2

[0074] This embodiment discloses an engine outlet water pressure overheat protection correction system, including:

[0075] A pressure sensor for obtaining the outlet water pressure value of the engine outlet pipe; the pressure sensor is installed on the engine outlet pipe;

[0076] A temperature sensor for obtaining the current outlet water temperature;

[0077] A control device for judging whether the engine water circuit is depressurized based on the outlet water pressure value;

[0078] If the engine water circuit is depressurized, based on the corresponding relationship between the outlet water pressure value and the coolant temperature, obtain the boiling point of the coolant at the current pressure;

[0079] Determine the engine overheat protection strategy based on the current outlet water temperature and the boiling point of the coolant at the current pressure.

[0080] Although the specific implementation manners of the present invention are described above in conjunction with the drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solutions of the present invention, various modifications or deformations that can be made by those skilled in the art without creative labor are still within the protection scope of the present invention.

Claims

1. A method for correcting overheat protection of the engine water outlet pressure, characterized in that, Including: Obtain the water outlet pressure value and the current water outlet temperature of the engine's water outlet pipe; Based on the water outlet pressure value, determine whether the engine water circuit is depressurized; The step of determining whether the engine water circuit is depressurized includes: if the current water outlet pressure value is less than the pressure value corresponding to the lowest temperature at which the original overheat protection strategy takes effect, the engine water circuit is depressurized; if the pressure value of the current circulating water circuit is greater than or equal to the pressure value corresponding to the lowest temperature at which the original overheat protection strategy takes effect, the engine water circuit is not depressurized; If the engine water circuit is depressurized, based on the correspondence between the water outlet pressure value and the coolant temperature, obtain the boiling point of the coolant at the current pressure; Determine the engine overheat protection strategy based on the current water outlet temperature and the boiling point of the coolant at the current pressure, specifically: Judge whether the current water outlet temperature is greater than the boiling point of the coolant at the current pressure; If the current water outlet temperature is greater than the boiling point of the corresponding coolant at the current pressure, correct the current water outlet temperature based on the water outlet temperature correction coefficient so that the corrected water temperature is greater than the lowest temperature at which the original overheat protection strategy takes effect; If the current water outlet temperature is less than or equal to the boiling point of the coolant at the current pressure, judge whether the current water outlet temperature is less than the opening temperature of the thermostat; If the current water outlet temperature is less than the opening temperature of the thermostat, there is no overheat risk for the engine; If the current water outlet temperature is greater than or equal to the opening temperature of the thermostat, correct the opening temperature of the cooling fan based on the current water outlet temperature.

2. The method for correcting overheat protection of the engine water outlet pressure according to claim 1, characterized in that, Use a pressure sensor installed on the engine's water outlet pipe to obtain the water outlet pressure value inside the engine's water outlet pipe.

3. The method for correcting overheat protection of the engine water outlet pressure according to claim 1, characterized in that, The lowest temperature at which the original overheat protection strategy takes effect is 115°C; the pressure value corresponding to the lowest temperature at which the original overheat protection strategy takes effect is one standard atmosphere.

4. The method for correcting overheat protection of the engine water outlet pressure according to claim 1, characterized in that, The correction of the current water outlet temperature based on the water outlet temperature correction coefficient includes: Based on the correspondence between the water outlet pressure and the water outlet temperature correction coefficient, determine the water outlet temperature correction coefficient at the current pressure; Multiply the water outlet temperature correction coefficient at the current pressure by the current water outlet temperature to obtain the corrected water temperature; The corrected water temperature is greater than 115°C.

5. The method for correcting overheat protection of the engine water outlet pressure according to claim 1, characterized in that, Based on a heat balance test, obtain the correspondence between the water outlet pressure value and the coolant temperature of the engine.

6. The method for correcting overheat protection of the engine water outlet pressure according to claim 1, characterized in that, If the engine water circuit is not depressurized, the control device controls the engine based on the original temperature overheat protection strategy.

7. An overheat protection correction system for the engine water outlet pressure, characterized in that, Including: A pressure sensor for obtaining the water outlet pressure value and the current water outlet temperature of the engine's water outlet pipe; A temperature sensor for obtaining the current water outlet temperature; A control device for determining whether the engine water circuit is depressurized based on the water outlet pressure value; The step of determining whether the engine water circuit is depressurized includes: if the current water outlet pressure value is less than the pressure value corresponding to the lowest temperature at which the original overheat protection strategy takes effect, the engine water circuit is depressurized; if the pressure value of the current circulating water circuit is greater than or equal to the pressure value corresponding to the lowest temperature at which the original overheat protection strategy takes effect, the engine water circuit is not depressurized; If the engine water circuit is depressurized, based on the correspondence between the water outlet pressure value and the coolant temperature, obtain the boiling point of the coolant at the current pressure; Determine the engine overheat protection strategy based on the current water outlet temperature and the boiling point of the coolant at the current pressure, specifically: Determine whether the current outlet water temperature is greater than the boiling point of the coolant at the current pressure; If the current outlet water temperature is greater than the boiling point of the corresponding coolant at the current pressure, correct the current outlet water temperature based on the outlet water temperature correction coefficient so that the corrected water temperature is greater than the lowest temperature at which the original overheat protection strategy takes effect; If the current outlet water temperature is less than or equal to the boiling point of the coolant at the current pressure, determine whether the current outlet water temperature is less than the opening temperature of the thermostat; If the current outlet water temperature is less than the opening temperature of the thermostat, there is no overheat risk for the engine; If the current outlet water temperature is greater than or equal to the opening temperature of the thermostat, correct the opening temperature of the radiator fan based on the current outlet water temperature.

8. A kind of engine water outlet pressure overheat protection correction system according to claim 7, characterized in that: The pressure sensor is installed on the engine outlet pipe.

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