Control system and method for over-exhaust-temperature protection of diesel engine

Abstract

The invention relates to the field of diesel engine control algorithms, in particular to a diesel engine over-exhaust-temperature protection control system and method.The diesel engine over-exhaust-temperature protection control system comprises a first comparator, a first selector, a second selector, a second comparator, a third comparator and an electronic control unit; the first selector is used for judging the size relation between the current vortex front exhaust temperature and a vortex front exhaust temperature limit value, the second selector is used for judging the size relation between the current intercooling inlet air temperature of the diesel engine and an intercooling inlet air temperature limit value, and the first selector and the second selector are used for selecting and outputting different torques for output results of different comparators. And the smaller value is selected based on the third comparator and is input into the electronic control unit, so that the electronic control unit can protect the engine from being damaged by ultrahigh exhaust temperature according to the pre-turbine temperature change of the diesel engine or the post-intercooling inlet air temperature change.

Description

Technical Field

[0001] The invention relates to the field of diesel engine control algorithms, and in particular to a control system and method for diesel engine over-exhaust temperature protection. Background Art

[0002] Diesel engines have become the main power source in the commercial vehicle field due to their high heat release efficiency and higher fuel utilization rate. With the implementation of the National VI Emissions Regulations, mainstream diesel engine systems all use exhaust gas recirculation systems (EGR) to control the original engine exhaust. However, when the exhaust temperature of the diesel engine is too high, it will lead to an increase in the fuel consumption rate and thermal load of the diesel engine, and will also cause the reliability of some diesel engine components to decrease due to the increase in thermal and mechanical loads. In addition, premature damage to parts due to overheating will increase the maintenance cost of the engine.

[0003] In order to prevent damage to the engine caused by excessive exhaust temperature, electronically controlled supercharged diesel engine systems generally use an engine over-exhaust temperature protection strategy based on the pre-turbine exhaust temperature (T3 temperature). This temperature is a model value calculated by the electronic control unit based on the air system, while taking into account corrections such as intake temperature, ambient temperature, and current vehicle speed. However, for diesel engines using an exhaust gas recirculation system (EGR), the accuracy of the model temperature can only be guaranteed when the EGR is turned off, so there is a risk of failure of this temperature protection strategy during actual operation. Summary of the invention

[0004] In view of the above problems, the present invention provides a control system and method for over-exhaust temperature protection of a diesel engine.

[0005] The adopted technical solution is a control system for diesel engine over-exhaust temperature protection, comprising a first comparator, a second comparator, a first selector, a second selector, a third comparator and an electronic control unit; The output terminal of the first comparator is connected to the input terminal of the first selector; The output terminal of the second comparator is connected to the input terminal of the second selector; The output terminal of the first selector and the output terminal of the second selector are connected to the input terminal of the third comparator; The output terminal of the third comparator is connected to the input terminal of the electronic control unit; The electronic control unit controls a torque value of the diesel engine based on an output result of the third comparator.

[0006] Optionally, the input end of the first comparator receives the current pre-turbine exhaust temperature and the pre-turbine exhaust temperature limit of the diesel engine system, and compares them, and outputs the comparison result to the first selector.

[0007] Optionally, the input end of the second comparator receives the current intercooler post-intake air temperature and the intercooler post-intake air temperature limit of the diesel engine system, and compares them, and the comparison result is output to the second selector.

[0008] Optionally, the first selector outputs the maximum torque of the diesel engine or the torque based on the current turbine pre-exhaust temperature protection limit to the third comparator according to the result output by the first comparator; The second selector outputs the maximum torque of the diesel engine or the protection torque based on the intake air temperature after the intercooler to the third comparator according to the result output by the second comparator. Optionally, the first comparator is used to compare whether the current pre-turbine exhaust temperature of the diesel engine is greater than or equal to the pre-turbine temperature limit value, and if so, the output result is 1, otherwise the output result is 0; The second comparator is used to compare whether the current post-intercooling intake air temperature of the diesel engine is greater than or equal to the post-intercooling intake air temperature limit value, and if so, the output result is 1, otherwise the output result is 0.

[0009] Optionally, when the output result of the first comparator changes from 0 to 1, the first selector outputs a protection torque of the diesel engine based on the current turbine exhaust temperature, otherwise, the first selector outputs a maximum engine torque of the diesel engine; When the output result of the second comparator changes from 0 to 1, the second selector outputs the protection torque of the diesel engine based on the intake air temperature after the intercooler, otherwise it outputs the maximum torque of the diesel engine.

[0010] Optionally, a third comparator compares the output result of the first selector with the output result of the second selector, and selects to output a smaller result to the electronic control unit; The electronic control unit outputs the current over-exhaust temperature protection torque of the diesel engine according to the output result of the third comparator.

[0011] The present application also provides a control method for diesel engine over-exhaust temperature protection, which is implemented based on a control system for diesel engine over-exhaust temperature protection and includes the following steps: C01. Get the current turbine pre-temperature and the current intercooler intake temperature of the diesel engine; C02. controlling the current over-exhaust temperature protection torque of the diesel engine according to the current turbine pre-temperature and the current intercooler post-intake air temperature.

[0012] Optionally, in C01, the current turbine pre-temperature of the diesel engine is the model temperature value of the electronic control unit, and the current intercooler rear intake temperature is the real-time value collected by the diesel engine system temperature sensor.

[0013] Optionally, in C02, if the current pre-turbine exhaust temperature of the diesel engine is greater than or equal to the pre-turbine temperature limit, the diesel engine is subjected to over-exhaust temperature protection based on the current pre-turbine exhaust temperature protection torque; Alternatively, if the current post-intercooler intake air temperature of the diesel engine is greater than or equal to the post-intercooler intake air temperature limit, the diesel engine is subjected to over-exhaust temperature protection based on the intercooler intake air temperature protection torque.

[0014] The benefits of the present invention include: 1. A diesel engine over-temperature limit control system is provided. Based on the control system, on the basis of limiting the over-exhaust temperature of the engine according to the current turbine pre-temperature T3 of the diesel engine, the engine intercooler intake temperature T22 is added as an over-temperature condition to realize the over-temperature protection function of the entire working process of the engine.

[0015] 2. At the same time, the first comparator is used to judge the size of the current exhaust temperature before the turbine and the limit value of the exhaust temperature before the turbine, and the second comparator is used to judge the size of the current intake temperature before the intercooler of the diesel engine and the limit value of the intake temperature before the intercooler. The first selector and the second selector can realize different torque control for the diesel engine according to different temperature changes. Based on the third comparator, the smaller torque value of the two can be selected and input to the electronic control unit, so that the electronic control unit can control the torque of the diesel engine according to the change of the temperature before the turbine and the change of the intake temperature after the intercooler. Therefore, the current intake temperature after the intercooler is the sensor temperature value monitored in real time by the diesel engine system. Therefore, adding a torque protection strategy for the change of the intake temperature after the intercooler can protect the diesel engine from the harm of excessive exhaust temperature in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a control system for diesel engine over-exhaust temperature protection; Figure 2 The present invention is a flow chart of a control method for diesel engine over-exhaust temperature protection. DETAILED DESCRIPTION

[0017] The following describes the implementation of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0018] It should be noted that the illustrations provided in the following embodiments are only used to schematically illustrate the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0019] like Figure 1 As shown, in view of the fact that the diesel engine in the prior art performs an ultra-high exhaust temperature protection strategy based on the pre-turbine temperature and needs the EGR system to be shut down to perform the protection action, there is a risk of failure of the protection strategy, a control system for diesel engine ultra-exhaust temperature protection is provided, including a first comparator 1, a second comparator 2, a first selector 3, a second selector 4, a third comparator 5 and an electronic control unit 6; The output end of the first comparator 1 is connected to the input end of the first selector 3; The output terminal of the second comparator 2 is connected to the input terminal of the second selector 4; The output end of the first selector 3 and the output end of the second selector 4 are connected to the input end of the third comparator 5; The output end of the third comparator 5 is connected to the input end of the electronic control unit 6; The electronic control unit 6 controls the torque value of the diesel engine based on the output result of the third comparator 5 .

[0020] Meanwhile, in this embodiment, the input end of the first comparator 1 receives the current pre-turbine exhaust temperature and the pre-turbine exhaust temperature limit of the diesel engine system, and compares them, and outputs the comparison result to the first selector 3 .

[0021] The input end of the second comparator 2 receives the current intercooler post-intake air temperature and the intercooler post-intake air temperature limit of the diesel engine system, and compares them, and outputs the comparison result to the second selector 4 .

[0022] Furthermore, the first selector 3 outputs the maximum torque of the diesel engine or the torque based on the current turbine exhaust temperature protection limit to the third comparator 5 according to the result output by the first comparator 1; The second selector 4 outputs the maximum torque of the diesel engine or the protection torque based on the intake air temperature after intercooling to the third comparator 5 according to the result output by the second comparator 2 .

[0023] At the same time, the first comparator 1 is used to compare whether the current pre-turbine exhaust temperature of the diesel engine is greater than or equal to the pre-turbine temperature limit value, and if so, the output result is 1, otherwise the output result is 0; The second comparator 2 is used to compare whether the current post-intercooling intake air temperature of the diesel engine is greater than or equal to the post-intercooling intake air temperature limit value, and if so, the output result is 1, otherwise the output result is 0.

[0024] Furthermore, when the output result of the first comparator 1 changes from 0 to 1, the first selector 3 outputs the protection torque of the diesel engine based on the current turbine exhaust temperature, otherwise it outputs the maximum torque of the diesel engine; When the output result of the second comparator 2 changes from 0 to 1, the second selector 4 outputs the protection torque of the diesel engine based on the intake air temperature after the intercooler, otherwise it outputs the maximum torque of the diesel engine.

[0025] Finally, the third comparator 5 compares the output result of the first selector 3 with the output result of the second selector 4, and selects and outputs the smaller result to the electronic control unit 6; The electronic control unit 6 outputs the current over-exhaust temperature protection torque of the diesel engine according to the output result of the third comparator 5 .

[0026] The purpose of such design is to provide an over-temperature limit control system for a diesel engine. Based on this control system, in addition to limiting the over-exhaust temperature of the engine according to the current pre-turbine temperature T3 of the diesel engine, the engine intercooler intake temperature T22 is also added as an over-temperature condition to achieve the over-temperature protection function of the entire engine working process.

[0027] At the same time, the first comparator is used to judge the size of the current exhaust temperature before the turbine and the exhaust temperature limit before the turbine, and the second comparator is used to judge the size of the current intake temperature before the intercooler of the diesel engine and the intake temperature limit before the intercooler. The first selector and the second selector can realize different torque control for the diesel engine according to different temperature changes. Based on the third comparator, the smaller torque value of the two can be selected and input to the electronic control unit, so that the electronic control unit can control the torque of the diesel engine according to the change of the temperature before the turbine and the change of the intake temperature after the intercooler. Therefore, the current intake temperature after the intercooler is the sensor temperature value monitored in real time by the diesel engine system. Therefore, adding a torque protection strategy for the change of the intake temperature after the intercooler can protect the diesel engine from the harm of excessive exhaust temperature in real time.

[0028] It should be pointed out that, in the description of this embodiment, the current exhaust temperature before the turbine is described as T3, and the current intake temperature after the intercooler is described as T22.

[0029] Based on this, if only the current turbine pre-turbine temperature of the diesel engine is greater than or equal to the turbine pre-turbine temperature limit, the diesel engine is controlled to output the protection torque based on the T3 temperature of the diesel engine; if only the current intercooler rear intake temperature of the diesel engine is greater than or equal to the intercooler rear temperature limit, the diesel engine is controlled to output the protection torque based on the intercooler rear intake temperature of the diesel engine; if only the current turbine pre-turbine temperature of the diesel engine is greater than or equal to the turbine pre-turbine temperature limit, and the current intercooler rear intake temperature of the diesel engine is greater than or equal to the intercooler rear temperature limit, then the diesel engine is controlled to output the smaller value of the protection torque based on the T3 temperature and the protection torque based on the intercooler rear intake temperature as the engine over-exhaust temperature protection torque; if the current turbine pre-turbine temperature of the diesel engine is less than the turbine pre-turbine temperature limit, and the current intercooler rear intake temperature of the diesel engine is also less than the intercooler rear temperature limit, then the diesel engine is controlled to output the maximum torque of the engine, that is, the engine is not torque limited.

[0030] like Figure 2 As shown, this embodiment also provides a control method for diesel engine over-exhaust temperature protection based on a control system for diesel engine over-exhaust temperature protection, comprising the following steps: C01. Get the current turbine pre-temperature and the current intercooler intake temperature of the diesel engine; C02. controlling the current over-exhaust temperature protection torque of the diesel engine according to the current turbine pre-temperature and the current intercooler post-intake air temperature.

[0031] At the same time, in C01, the current turbine pre-temperature of the diesel engine is the model temperature value of the electronic control unit (6), and the current intercooler intake air temperature is the real-time value collected by the diesel engine system temperature sensor.

[0032] Furthermore, in C02, according to the current pre-turbine exhaust temperature of the diesel engine being greater than or equal to the pre-turbine temperature limit, the diesel engine is subjected to over-exhaust temperature protection based on the current pre-turbine exhaust temperature protection torque; Alternatively, if the current post-intercooler intake air temperature of the diesel engine is greater than or equal to the post-intercooler intake air temperature limit, the diesel engine is subjected to over-exhaust temperature protection based on the intercooler intake air temperature protection torque.

[0033] The control method of diesel engine over-exhaust temperature is explained with a specific example: For a certain type of diesel engine, the turbine pre-temperature limit is 730°C, and the intercooler intake temperature limit is 70°C. If the current turbine pre-temperature is 700°C or lower, and the intercooler intake temperature is 69°C or lower, the diesel engine will not perform over-exhaust temperature torque limit protection, and the diesel engine can operate at any speed within the maximum torque range of the engine. If the current turbine pre-temperature is 740°C and the intercooler intake temperature is 69°C or lower, the diesel engine executes the protection torque based on the turbine pre-temperature, then the engine can only operate under the working conditions below the protection torque range.

[0034] If the current turbine pre-temperature is 700°C or lower and the intake air temperature after the intercooler is 75°C, the diesel engine executes the protection torque based on the intake air temperature after the intercooler, and the engine can only operate under the working conditions below the protection torque range.

[0035] If the current turbine pre-temperature is 750°C and the intercooler intake temperature is 75°C, the diesel engine executes the smaller value of the protection torque based on the turbine pre-temperature and the protection torque based on the intercooler intake temperature, then the engine can only operate under the operating conditions below the protection torque range.

[0036] By implementing the diesel engine over-exhaust temperature control system and method, the diesel engine can be protected in real time to operate within a reasonable temperature range, ensuring that the engine is not damaged by excessively high exhaust temperatures.

[0037] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A control system for diesel engine over-exhaust temperature protection, characterized in that: It comprises a first comparator (1), a second comparator (2), a first selector (3), a second selector (4), a third comparator (5) and an electronic control unit (6); The output end of the first comparator (1) is connected to the input end of the first selector (3); The output end of the second comparator (2) is connected to the input end of the second selector (4); The output end of the first selector (3) and the output end of the second selector (4) are connected to the input end of the third comparator (5); The output end of the third comparator (5) is connected to the input end of the electronic control unit (6); The electronic control unit (6) controls the torque value of the diesel engine based on the output result of the third comparator (5).

2. A diesel engine over-exhaust temperature protection control system according to claim 1, characterized in that: The input end of the first comparator (1) receives the current pre-turbine exhaust temperature and the pre-turbine exhaust temperature limit of the diesel engine system, and compares them, and outputs the comparison result to the first selector (3).

3. A diesel engine over-exhaust temperature protection control system according to claim 2, characterized in that: The input end of the second comparator (2) receives the current intercooler post-intake air temperature and the intercooler post-intake air temperature limit of the diesel engine system, and compares them, and outputs the comparison result to the second selector (4).

4. A diesel engine over-exhaust temperature protection control system according to claim 3, characterized in that: The first selector (3) outputs the maximum torque of the diesel engine or the torque based on the current turbine exhaust temperature protection limit to the third comparator (5) according to the result output by the first comparator (1); The second selector (4) outputs the maximum torque of the diesel engine or the protection torque based on the intake air temperature after the intercooler to the third comparator (5) according to the result output by the second comparator (2).

5. A diesel engine over-exhaust temperature protection control system according to claim 4, characterized in that: The first comparator (1) is used to compare whether the current pre-turbine exhaust temperature of the diesel engine is greater than or equal to the pre-turbine temperature limit value, and if so, the output result is 1, otherwise the output result is 0; The second comparator (2) is used to compare whether the current intercooler intake air temperature of the diesel engine is greater than or equal to the intercooler intake air temperature limit value, and if so, the output result is 1, otherwise the output result is 0.

6. A diesel engine over-exhaust temperature protection control system according to claim 5, characterized in that: The first selector (3) outputs a protection torque of the diesel engine based on the current turbine exhaust temperature when the output result of the first comparator (1) changes from 0 to 1, and otherwise outputs the maximum engine torque of the diesel engine; The second selector (4) outputs the protection torque of the diesel engine based on the intake air temperature after the intercooler when the output result of the second comparator (2) changes from 0 to 1, and otherwise outputs the maximum engine torque of the diesel engine.

7. A diesel engine over-exhaust temperature protection control system according to claim 6, characterized in that: The third comparator (5) compares the output result of the first selector (3) and the output result of the second selector (4), and selects and outputs the smaller result to the electronic control unit (6); The electronic control unit (6) outputs the current over-exhaust temperature protection torque of the diesel engine according to the output result of the third comparator (5).

8. A control method for diesel engine over-exhaust temperature protection, implemented based on a control system for diesel engine over-exhaust temperature protection in claim 6, characterized in that: The following steps are involved: C01. Get the current turbine pre-temperature and the current intercooler intake temperature of the diesel engine; C02. controlling the current over-exhaust temperature protection torque of the diesel engine according to the current turbine pre-temperature and the current intercooler post-intake air temperature.

9. A diesel engine over-exhaust temperature protection control system according to claim 8, characterized in that: In C01, the current turbine pre-temperature of the diesel engine is the model temperature value of the electronic control unit (6), and the current intercooler intake air temperature is the real-time value collected by the diesel engine system temperature sensor.

10. A diesel engine over-exhaust temperature protection control system according to claim 8, characterized in that: In C02, if the current exhaust temperature before turbine of the diesel engine is greater than or equal to the temperature limit before turbine, the diesel engine is subjected to over-exhaust temperature protection based on the current exhaust temperature protection torque before turbine; Alternatively, if the current post-intercooler intake air temperature of the diesel engine is greater than or equal to the post-intercooler intake air temperature limit, the diesel engine is subjected to over-exhaust temperature protection based on the intercooler intake air temperature protection torque.

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