Water temperature control strategy for preventing engine cylinder score
By setting temperature thresholds for different stages in the engine and dynamically limiting engine output torque and speed, the problem of cylinder scoring under extreme temperatures is solved, improving engine reliability and user experience.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGXI YUCHAI MASCH CO LTD
- Filing Date
- 2025-12-15
- Publication Date
- 2026-04-24
AI Technical Summary
Existing engine thermal management technologies cannot provide precise protection, which makes engines prone to cylinder scoring under extreme temperatures, affecting the user's driving experience and engine reliability.
By acquiring engine operating conditions and real-time coolant temperature, temperature thresholds are set for different stages to limit engine output torque and speed. A gradual limiting strategy is adopted to avoid the risk of cylinder scoring, including dynamic adjustment of fuel injection quantity and throttle opening.
It effectively avoids the risk of cylinder scoring caused by improper user operation, improves engine reliability and service life, while taking into account drivability and power, and provides comprehensive temperature protection.
Smart Images
Figure CN121916094A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to engine control technology, and more specifically, to a water temperature control strategy to prevent engine cylinder scoring. Background Technology
[0002] Engine cylinder scoring is a serious fault. It directly leads to increased engine friction losses, reduced power, and in severe cases, can render the engine unusable. One of the main causes of cylinder scoring is poor thermal management conditions. During a cold start, especially when the ambient temperature is extremely low, the engine coolant temperature is low, the cylinder bore expansion is minimal, and the engine oil viscosity is high with poor flowability. If the user immediately engages in high-speed, high-load operation at this time, the piston will heat up rapidly, resulting in a large piston expansion. In particular, the expansion coefficient of aluminum pistons is twice that of steel cylinder bores. This large piston expansion and small cylinder bore expansion leads to a reduction in cylinder clearance, which can easily cause cylinder scoring.
[0003] When the engine overheats, the coolant temperature becomes too high, the piston and cylinder bore undergo excessive thermal deformation, the oil viscosity decreases, and the oil film strength weakens, making it difficult to form effective lubrication and greatly increasing the risk of cylinder scoring.
[0004] In existing technology, engines typically have a coolant temperature warning light, but this warning only indicates that the coolant temperature is high. It cannot provide precise protection across the entire engine operating temperature range, potentially affecting the user's normal driving experience or failing to completely avoid risks. Summary of the Invention
[0005] The technical problem to be solved by the present invention is to provide a water temperature control strategy to prevent engine cylinder scoring, which addresses the shortcomings of the existing technology and solves the technical problem that the existing engine thermal management technology cannot provide fine protection and easily leads to engine cylinder scoring.
[0006] The present invention discloses a water temperature control strategy for preventing engine cylinder scoring. The strategy includes: acquiring the engine operating stage and real-time coolant temperature; determining a graded stage based on the engine operating stage; setting a temperature threshold for each graded stage; and limiting the engine output torque and engine speed based on the real-time coolant temperature and the temperature thresholds of each graded stage.
[0007] To further improve the method, the engine output torque is limited based on the real-time coolant temperature and the temperature thresholds for each stage. When the real-time coolant temperature is equal to the temperature threshold of the graded stage, the coolant temperature-injection limit coefficient calibration curve is obtained. The injection limit coefficient is calibrated according to the real-time coolant temperature and the coolant temperature-injection limit coefficient calibration curve. The injection quantity limit threshold is calibrated according to the injection limit coefficient. The cyclic injection quantity of the engine is limited by the injection quantity limit threshold, thereby limiting the output torque of the engine.
[0008] Furthermore, the method for limiting engine speed based on the real-time coolant temperature and the temperature thresholds for each stage is as follows: When the real-time coolant temperature is equal to the temperature threshold of the graded stage, the coolant temperature-throttle limit coefficient calibration curve is obtained. The throttle limit coefficient is calibrated according to the real-time coolant temperature and the coolant temperature-throttle limit coefficient calibration curve. The throttle limit threshold is calibrated according to the throttle limit coefficient. The throttle opening is limited by the throttle limit threshold, thereby limiting the engine speed.
[0009] Furthermore, the engine operating phase includes the engine start-up and initial operation phase and the engine operation phase.
[0010] Furthermore, the method for determining the graded stages based on the engine's operating stages is as follows: When the engine working stage is the engine start-up and initial operation stage, the graded stage includes a first low temperature stage, a second low temperature stage, a third low temperature stage, and a normal operation stage. When the engine is in the engine operation phase, the graded phases include a first high temperature phase, a second high temperature phase, and an emergency protection phase.
[0011] Furthermore, the method for setting temperature thresholds for each of the aforementioned grading stages is as follows: When the grading stage is the first low temperature stage, the temperature threshold is set to be less than the first temperature; When the grading stage is the second low temperature stage, the temperature threshold is set to be greater than or equal to the first temperature and less than the second temperature. When the grading stage is the third low temperature stage, the temperature threshold is set to be greater than or equal to the second temperature and less than the third temperature. When the grading stage is the normal working stage, the temperature threshold is set to be greater than or equal to the third temperature and less than the fourth temperature. When the grading stage is the first high temperature stage, the temperature threshold is set to the fourth temperature. When the grading stage is the second high temperature stage, the temperature threshold is set to the fifth temperature. When the grading stage is the emergency protection stage, the temperature threshold is set to the sixth temperature.
[0012] Furthermore, the first temperature is 20°C, the second temperature is 40°C, the third temperature is 70°C, the fourth temperature is 108°C, the fifth temperature is 110°C, and the sixth temperature is 112°C.
[0013] Furthermore, when the real-time coolant temperature equals the temperature threshold of the emergency protection phase, the engine is shut down.
[0014] Beneficial effects The advantages of this invention are: 1. This invention acquires the engine operating stage and real-time coolant temperature, determines graded stages based on the engine operating stage, sets temperature thresholds for each graded stage, and limits the engine output torque and engine speed based on the real-time coolant temperature and the temperature thresholds for each graded stage. By actively limiting engine operating conditions, it fundamentally avoids the risk of cylinder scoring caused by improper user operation under adverse water temperature conditions, greatly improving engine reliability and service life. The invention sets multiple temperature thresholds and a progressive limiting strategy, ensuring absolute safety under extreme temperatures while gradually relaxing restrictions as the temperature approaches normal, thus balancing vehicle drivability and power, resulting in a better user experience.
[0015] 2. The present invention determines the graded stages based on the engine's operating stages, including low-temperature stages and high-temperature stages, and considers two completely different operating conditions, namely low-temperature cold start and high-temperature overheating, both of which can lead to cylinder scoring, thus providing comprehensive protection. Attached Figure Description
[0016] Figure 1 This is a flowchart illustrating the overall water temperature control strategy for preventing engine cylinder scoring according to the present invention. Figure 2 This is a schematic diagram of the coolant temperature-injection limit coefficient calibration curve of the present invention; Figure 3 This is a MAP diagram used in this invention for calibrating the fuel injection quantity limit threshold. Detailed Implementation
[0017] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made by any person within the scope of the claims of the present invention are still within the scope of the claims of the present invention. See Figures 1-3This invention discloses a water temperature control strategy to prevent engine cylinder scoring. The strategy includes: acquiring the engine operating stage and real-time coolant temperature; determining graded stages based on the engine operating stage; setting temperature thresholds for each graded stage; and outputting corresponding fuel injection quantity limit thresholds and throttle limit thresholds for each graded stage based on the real-time coolant temperature and the temperature thresholds for each graded stage. The fuel injection quantity limit threshold restricts the engine's cyclic fuel injection quantity or intake air volume, thereby limiting the engine's output torque. The throttle limit threshold restricts the throttle opening, thereby limiting the engine speed. By actively limiting engine operating conditions, the risk of cylinder scoring due to improper user operation under unfavorable water temperature conditions is fundamentally avoided, greatly improving engine reliability and service life.
[0018] The engine operating phase includes the engine start-up and initial operation phase and the engine running phase. The method for determining the graded phases based on the engine operating phase is as follows: like Figure 1 As shown, when the engine is in the initial stage of engine start-up and operation, the stage is divided into three phases: the first low temperature stage, the second low temperature stage, the third low temperature stage, and the normal operation stage.
[0019] When the engine is in the engine operation phase, the graded phases include the first high temperature phase, the second high temperature phase, and the emergency protection phase.
[0020] The method for setting temperature thresholds for each grading stage is as follows: When the grading stage is the first low temperature stage, the temperature threshold is set to be lower than the first temperature. When the grading stage is the first low temperature stage, the engine output torque is limited to no more than 30% of its maximum torque, and the engine speed is limited to no more than 50% of its rated speed.
[0021] When the grading stage is the second low temperature stage, the temperature threshold is set to be greater than or equal to the first temperature and less than the second temperature, limiting the engine output torque to no more than 50% of its maximum torque, and limiting the engine speed to no more than 70% of its rated speed.
[0022] When the grading stage is the third low temperature stage, the temperature threshold is set to be greater than or equal to the second temperature and less than the third temperature, limiting the engine output torque to no more than 70% of its maximum torque, and limiting the engine speed to no more than 90% of its rated speed.
[0023] When the graded stage is the normal operating stage, the temperature threshold is set to be greater than or equal to the third temperature and less than the fourth temperature, all restrictions are lifted, and the engine is allowed to operate normally at full load and rated speed or higher.
[0024] When the grading stage is the first high temperature stage, the temperature threshold is set to the fourth temperature to limit the engine output torque, reducing it by 10% from the current engine output torque.
[0025] When the grading stage is the second high temperature stage, the temperature threshold is set to the fifth temperature to further limit the engine output torque, reducing it by 30% from the current level.
[0026] Based on the engine's operating stages, a graded stage is determined, including a low-temperature stage and a high-temperature stage. It also considers two distinct operating conditions—low-temperature cold start and high-temperature overheating—both of which can lead to cylinder scoring, providing comprehensive protection.
[0027] When the classification stage is the emergency protection stage, the temperature threshold is set to the sixth temperature, and the engine shutdown command is executed to force the engine to shut down in order to avoid irreversible cylinder scoring damage.
[0028] The first temperature is 20℃, the second is 40℃, the third is 70℃, the fourth is 108℃, the fifth is 110℃, and the sixth is 112℃. Multiple temperature thresholds and a progressive restriction strategy are set to ensure absolute safety under extreme temperatures while gradually relaxing restrictions as the temperature approaches normal, thus balancing vehicle drivability and power for a better user experience.
[0029] The method for limiting engine output torque based on real-time coolant temperature and temperature thresholds for each stage is as follows: when the real-time coolant temperature equals the temperature threshold for each stage, obtain... Figure 2 The coolant temperature-injection limit coefficient calibration curve shown is used to calibrate the injection limit coefficient based on the real-time coolant temperature and the coolant temperature-injection limit coefficient calibration curve. The injection quantity limit threshold is then calibrated based on the injection limit coefficient, and the engine output torque is limited by the injection quantity limit threshold. Figure 3 A MAP diagram for calibrating the fuel injection quantity limit threshold.
[0030] The method for limiting engine speed based on real-time coolant temperature and temperature thresholds at each stage is as follows: When the real-time coolant temperature equals the temperature threshold of each stage, a coolant temperature-throttle limit coefficient calibration curve is obtained. The throttle limit coefficient is calibrated based on the real-time coolant temperature and the coolant temperature-throttle limit coefficient calibration curve. The throttle limit threshold is then calibrated based on the throttle limit coefficient. Finally, the engine speed is limited based on the throttle limit threshold. Both the coolant temperature-injection limit coefficient calibration curve and the coolant temperature-throttle limit coefficient calibration curve are obtained from extensive experimental data. The method for obtaining the coolant temperature-throttle limit coefficient calibration curve is the same as that for the coolant temperature-injection limit coefficient calibration curve. Therefore, this invention does not provide a schematic diagram of the coolant temperature-throttle limit coefficient calibration curve. Similarly, the calibration diagram of the throttle limit threshold is also obtained from extensive experimental data. Therefore, this invention does not provide a MAP diagram for calibrating the throttle limit threshold.
[0031] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.
Claims
1. A water temperature control strategy to prevent engine cylinder scoring, characterized in that, The strategy includes acquiring the engine operating stage and real-time coolant temperature, determining a graded stage based on the engine operating stage, setting a temperature threshold for each graded stage, and limiting the engine output torque and engine speed based on the real-time coolant temperature and the temperature thresholds for each graded stage.
2. The water temperature control strategy for preventing engine cylinder scoring according to claim 1, characterized in that, The method for limiting engine output torque based on the real-time coolant temperature and the temperature thresholds of each stage is as follows: When the real-time coolant temperature is equal to the temperature threshold of the graded stage, the coolant temperature-injection limit coefficient calibration curve is obtained. The injection limit coefficient is calibrated according to the real-time coolant temperature and the coolant temperature-injection limit coefficient calibration curve. The injection quantity limit threshold is calibrated according to the injection limit coefficient. The cyclic injection quantity of the engine is limited by the injection quantity limit threshold, thereby limiting the output torque of the engine.
3. The water temperature control strategy for preventing engine cylinder scoring according to claim 1, characterized in that, The method for limiting engine speed based on the real-time coolant temperature and the temperature thresholds of each stage is as follows: When the real-time coolant temperature is equal to the temperature threshold of the graded stage, the coolant temperature-throttle limit coefficient calibration curve is obtained. The throttle limit coefficient is calibrated according to the real-time coolant temperature and the coolant temperature-throttle limit coefficient calibration curve. The throttle limit threshold is calibrated according to the throttle limit coefficient. The throttle opening is limited by the throttle limit threshold, thereby limiting the engine speed.
4. The water temperature control strategy for preventing engine cylinder scoring according to claim 1, characterized in that, The engine operating phases include the engine start-up and initial operation phase and the engine operation phase.
5. The water temperature control strategy for preventing engine cylinder scoring according to claim 4, characterized in that, The method for determining the graded stages based on the engine's operating stages is as follows: When the engine working stage is the engine start-up and initial operation stage, the graded stage includes a first low temperature stage, a second low temperature stage, a third low temperature stage, and a normal operation stage. When the engine is in the engine operation phase, the graded phases include a first high-temperature phase, a second high-temperature phase, and an emergency protection phase.
6. The water temperature control strategy for preventing engine cylinder scoring according to claim 5, characterized in that, The method for setting temperature thresholds for each of the aforementioned grading stages is as follows: When the grading stage is the first low temperature stage, the temperature threshold is set to be less than a preset first temperature; When the grading stage is the second low temperature stage, the temperature threshold is set to be greater than or equal to the first temperature and less than the preset second temperature; When the grading stage is the third low temperature stage, the temperature threshold is set to be greater than or equal to the second temperature and less than the preset third temperature; When the grading stage is the normal working stage, the temperature threshold is set to be greater than or equal to the third temperature and less than the preset fourth temperature; When the grading stage is the first high temperature stage, the temperature threshold is set to the fourth temperature. When the grading stage is the second high temperature stage, the temperature threshold is set to a preset fifth temperature; When the grading stage is the emergency protection stage, the temperature threshold is set to the preset sixth temperature.
7. The water temperature control strategy for preventing engine cylinder scoring according to claim 6, characterized in that, The first temperature is 20℃, the second temperature is 40℃, the third temperature is 70℃, the fourth temperature is 108℃, the fifth temperature is 110℃, and the sixth temperature is 112℃.
8. The water temperature control strategy for preventing engine cylinder scoring according to claim 6, characterized in that, When the real-time coolant temperature equals the temperature threshold of the emergency protection phase, the engine will be shut down.