A method for low-temperature protection of an engine bearing, a control system and a calibration system

Abstract

The application discloses an engine bearing bush low-temperature protection method, a control system and a calibration system, and belongs to the technical field of automobiles, and comprises the following steps: S1, collecting working condition signals and calculating in real time; wherein the working condition signals comprise engine oil temperature and engine instantaneous speed, and the engine oil temperature rising rate and the speed climbing rate are obtained through calculation; S2, according to a pre-calibrated steady speed table and a climbing rate table, the highest steady speed corresponding to the engine oil temperature and the maximum speed climbing rate are obtained; S3, according to the engine oil temperature rising rate, the highest steady speed correction value and the maximum speed climbing rate correction value are obtained; and S4, the engine oil temperature is compared with a low-temperature locking threshold value and a high-temperature unlocking threshold value, and it is determined whether to enter a locking state or an unlocking state. The application synchronously controls the maximum steady speed corresponding to the engine oil temperature and the maximum speed climbing rate, and fills the protection blank of the prior art which only controls the steady speed.

Description

Technical Field

[0001] This invention relates to the field of automotive technology, and in particular to a method, control system, and calibration system for low-temperature protection of engine bearings. Background Technology

[0002] Reciprocating internal combustion engines include two main categories: gasoline engines and diesel engines. The sliding bearing friction pairs, such as crankshaft main bearings, connecting rod bearings, and balance shaft bushings, rely on the oil film of the engine oil for friction reduction and support, and are core components ensuring reliable and durable engine operation. In extremely cold environments (-20℃ to 40℃), the viscosity of the engine oil increases significantly, and its fluidity decreases, resulting in a significant delay in the establishment of the oil film after engine start-up. If the driver suddenly accelerates at this time, the engine speed increases rapidly, and the bearing friction pairs are prone to boundary dry friction, leading to bearing scoring and failure.

[0003] The general logic of existing electronic control protection schemes is as follows: real-time acquisition of oil temperature in the oil pan, comparison of the measured oil temperature with a preset temperature threshold; when the oil temperature is lower than the set low-temperature threshold, a single MAP meter is retrieved to limit the maximum steady-state engine speed; once the oil temperature rises to the unlocking threshold, the speed limit is lifted. This scheme only controls the engine's maximum steady-state speed and does not constrain the dynamic rate of speed increase; it also uses a single-stage temperature threshold control logic without hysteresis buffer design. The industry's conventional calibration process relies on engineers' experience to manually set speed limit boundaries, lacking a standardized bench calibration method for determining critical wear. The specific problems mentioned above are: 1. Limiting only the steady-state maximum speed without constraining the speed ramp-up rate still poses a risk of bearing failure during rapid acceleration in extremely cold conditions. This is because oil flow is slow at low temperatures, and there is a time lag in oil film formation. Even if the steady-state speed is reduced, a sudden acceleration by the driver will cause the speed to spike rapidly in a short period. The bearing friction pair will be subjected to high-load impact before the oil film is fully formed, resulting in dry friction damage. Current technology generally believes that limiting the maximum speed is sufficient for protection, ignoring the instantaneous impact load caused by dynamic changes in speed. This instantaneous wear failure cannot be eliminated by simply limiting the steady-state speed in the long term.

[0004] 2. Single threshold switching logic: Small temperature fluctuations can cause the protection strategy to frequently start and stop, exacerbating wear. This is because the oil temperature fluctuates slightly when driving in low temperatures and alternating between idling and driving. A single unlocking and locking threshold will cause the ECU to repeatedly switch between speed limiting and normal modes, resulting in frequent changes in torque and speed. The oil film condition remains unstable, which in the long term exacerbates bearing fatigue wear.

[0005] The industry's conventional control logic does not set a temperature range, sacrificing low-temperature operation stability in order to simplify the control logic.

[0006] 3. Calibration relies on manual experience and lacks a standardized critical wear determination process, making it impossible to quantify safety margins. This is because existing MAP calibrations depend solely on subjective human judgment of wear boundaries, failing to simultaneously collect multi-dimensional critical signals such as bearing temperature, oil pressure, and engine vibration. Speed ​​limit threshold margins are entirely determined by engineers' experience, resulting in poor consistency in protection reliability. There is a lack of a reproducible and quantifiable bench calibration process, leading to significant differences in low-temperature speed limit standards across different engine models and manufacturers.

[0007] 4. The control logic has a high degree of coupling between different engine models, resulting in high costs for cross-engine reuse and difficulty in extending to the protection of bearing-related friction pairs. This is because the existing low-temperature speed protection control logic is deeply bound to the fuel injection and combustion control logic specific to gasoline / diesel engines. Speed ​​limiting MAPs and control algorithms developed for gasoline engines cannot be directly ported to diesel engines. For each new engine model, companies need to complete a full bench calibration and vehicle low-temperature verification, significantly increasing the development cycle and calibration costs. At the same time, the current strategy only focuses on the protection of crankshaft main bearings and connecting rod bearings, and has not formed a unified protection framework that can be universally adapted to similar thin-walled sliding friction pairs such as camshaft bushings and balance shaft bearings. If protection of other bearing friction pairs is required, an additional independent control branch needs to be added, resulting in poor software architecture scalability. The industry's traditional development approach uses a single engine model and a single friction pair combination as the development unit, without designing a universal control system that is not bound to the combustion system and adapts to all types of bearing sliding friction pairs. This leads to insufficient reusability in the batch development of multiple types of internal combustion engines and multiple types of bearings.

[0008] 5. Hardware protection solutions have high material costs, hindering cost reduction in mass production. This is because relying on upgrading bearing materials and adding preheating devices to address low-temperature wear significantly increases the cost of individual engine components; specialized antifreeze engine oil also increases end-user costs. Hardware optimization solutions cannot reduce the bearing configuration level at the control logic level without adding hardware or replacing high-specification parts. Summary of the Invention

[0009] The purpose of this invention is to provide a method, control system, and calibration system for low-temperature protection of engine bearings, solving the problems of existing technologies that only limit the steady-state maximum speed without constraining the speed ramp-up rate, which cannot eradicate the instantaneous dry grinding and bearing failure faults during rapid acceleration in extreme cold; the use of a single oil temperature threshold switching protection logic, which leads to frequent start-stop of the control strategy when the temperature fluctuates slightly, exacerbating bearing fatigue wear; the existing low-temperature speed limiting MAP relies on manual experience for calibration, lacks a standardized bench critical wear judgment process, cannot quantify the speed limiting safety margin, and has poor protection consistency; the existing control logic is deeply coupled with the engine combustion system, resulting in high reuse costs across gasoline and diesel engines, and is difficult to easily extend to the protection of other sliding friction pairs such as camshaft bushings and balance shaft bearings; and hardware protection solutions require upgrading bearing materials and adding preheating devices, resulting in high overall material costs and insufficient economic benefits for mass production.

[0010] In a first aspect, the present invention discloses a method for low-temperature protection of engine bearings, comprising: S1: Real-time acquisition and calculation of operating condition signals; wherein, the operating condition signals include oil temperature and instantaneous engine speed, and the oil temperature rise rate and engine speed climb rate are calculated. S2: Based on the pre-calibrated steady-state speed table and creep rate table, obtain the highest steady-state speed and the maximum speed creep rate corresponding to the oil temperature; S3: Obtain the highest steady-state speed correction value and the maximum speed climb rate correction value based on the oil temperature rise rate; S4: Compare the engine oil temperature with the preset temperature threshold to determine whether to enter the lock or unlock state; When in the locked state, the instantaneous engine speed is compared with the correction value for the highest steady-state speed, and the speed climb rate is compared with the correction value for the maximum speed climb rate. If the instantaneous engine speed is greater than the maximum steady-state speed correction value, then the fuel injection quantity or intake air quantity is limited to reduce the speed to below the corrected maximum steady-state speed. If the engine speed climb rate is greater than the maximum engine speed climb rate correction value, then the throttle response rate is limited, and the engine speed climb rate is reduced.

[0011] Preferably, comparing the engine oil temperature with a preset temperature threshold to determine whether to enter a locked or unlocked state specifically includes: The temperature threshold is a temperature range; When the oil temperature is less than or equal to the lower limit of the temperature range, it enters a lock-up state; When the engine oil temperature is greater than or equal to the upper limit of the temperature range, the system enters the unlocked state. When the engine oil temperature is within the specified temperature range, maintain the current state.

[0012] Preferably, the calibration process for the steady-state tachometer and the climb rate meter is as follows: The oil pan is equipped with an independent temperature control fixture, which sets multiple constant temperature points with progressively increasing temperatures, and sets a preset holding time for each constant temperature point. Within each constant temperature point, the steady-state speed and the speed increase rate are gradually increased according to preset levels. Three sets of signals are collected simultaneously: bearing temperature change signal, oil main pressure instantaneous drop signal, and engine vibration amplitude signal. If any one of the three signals reaches the corresponding critical threshold, it is determined that the bearing dry friction critical boundary has been reached. The corresponding steady-state speed and speed increase rate are reduced by a preset ratio to become the highest steady-state speed and maximum speed increase rate at that constant temperature point. The highest steady-state speed and the maximum speed increase rate corresponding to all constant temperature points are entered into a two-dimensional data table to generate a steady-state speed table and a speed increase rate table, which are then stored.

[0013] Preferably, step S3 specifically includes: If the rate of increase in oil temperature rise increases, then the highest steady-state speed and the maximum speed rise rate obtained by S2 are adjusted upwards to obtain the correction values ​​for the highest steady-state speed and the maximum speed rise rate. If the rate of increase of engine oil temperature remains unchanged or decreases, the highest steady-state speed and the maximum speed increase rate obtained from S2 are directly used as the correction values ​​for the highest steady-state speed and the maximum speed increase rate.

[0014] Preferably, before step S1, the method further includes: During the power-on but not ignition phase, the engine oil temperature is predicted; if the engine oil temperature is less than or equal to the preset ignition temperature threshold, the maximum throttle speed is locked.

[0015] Preferably, the operating condition signal in step S1 further includes the accelerator pedal opening. In step S4, if the speed increase rate is greater than the maximum speed increase rate correction value, then the accelerator pedal output response slope is attenuated according to the oil temperature range, and the speed increase rate is indirectly constrained by limiting the throttle signal change rate. If the indirect constraint on the speed increase rate is not effective, then the throttle response rate is limited to reduce the speed increase rate.

[0016] Preferably, the method further includes step S5: outputting corrected fuel injection quantity and intake air quantity control signals based on the highest steady-state speed and the accelerator pedal output response slope.

[0017] Secondly, the present invention also discloses a low-temperature protection control system for engine bearings, comprising: The ECU is used to perform the engine bearing low-temperature protection method mentioned above. The ECU has a built-in erasable and rewritable memory unit for storing the calibrated steady-state tachometer, the ramp rate table and the preset temperature threshold. The oil temperature sensor is used to communicate with the ECU's analog signal acquisition port to collect the oil temperature in the oil pan in real time. The crankshaft speed sensor is connected to the ECU speed acquisition channel and is used to output the instantaneous engine speed signal.

[0018] Thirdly, the present invention also describes an engine bearing low-temperature protection calibration system comprising: an ECU for performing the above-mentioned engine bearing low-temperature protection method, wherein the ECU has a built-in erasable and rewritable memory unit for storing a steady-state speed table and a climb rate table; The oil temperature sensor is used to communicate with the ECU's analog signal acquisition port to collect the oil temperature in the oil pan in real time. The crankshaft speed sensor is used to connect to the ECU speed acquisition channel and output the instantaneous engine speed signal; The vibration sensor, main oil passage pressure sensor, and bearing temperature thermocouple connected to the ECU calibration port are used to acquire the engine vibration amplitude signal, the instantaneous drop signal of the main oil pressure, and the sudden change signal of the bearing temperature, respectively.

[0019] Fourthly, the present invention also describes a vehicle including the aforementioned engine bearing low-temperature protection control system.

[0020] Compared with the prior art, the present invention has the following advantages: 1. This invention simultaneously controls the maximum steady-state speed and the maximum speed climb rate corresponding to the oil temperature, filling the gap in existing technologies that only control steady-state speed. Under extreme cold start-up and rapid acceleration conditions at -35℃, the instantaneous dry friction failure rate of the bearing is reduced from 12.7% in existing solutions to nearly zero; the impact load on the bearing during the oil film formation stage is reduced by more than 90%, simultaneously providing complete protection for the main bearing and connecting rod bearings, eliminating the potential for bearing failure due to low-temperature rapid acceleration. A temperature-steady-state speed-speed climb rate MAP is generated, fully covering dynamic driving conditions such as cold starts and instantaneous rapid acceleration. Compared to the traditional single static speed threshold MAP, the speed limit matching accuracy under actual vehicle dynamic conditions is significantly improved, avoiding the shortcomings of traditional solutions that either have excessive protection redundancy and severely limited power, or insufficient protection and risk of bearing failure. After the oil temperature recovers, the speed and climb rate limits are automatically relaxed. Compared to the traditional single conservative threshold calibration scheme, the vehicle's power response is improved by 15%-30% in mild low-temperature environments, significantly improving the driving experience of vehicles in cold regions.

[0021] 2. This invention sets dual threshold temperature ranges for temperature rise unlocking and temperature fall lock-up, avoiding repeated switching of speed limiting strategies caused by small fluctuations in engine oil temperature. The ECU output torque and speed commands do not frequently change, and the bearing oil film remains consistently stable. Under long-term low-temperature cyclic conditions, the alternating fatigue wear of the bearings decreases by 75%, and the engine's low-temperature operating smoothness is significantly improved.

[0022] 3. This invention uses multi-dimensional sensors to simultaneously collect bearing temperature, oil pressure, and engine vibration signals, objectively determining the critical wear boundary of the bearing. A MAP is generated by uniformly adjusting a fixed safety margin based on the critical value, replacing manual subjective calibration. The deviation of the low-temperature speed limit threshold for different engine models and batches is controlled within 5%, significantly improving calibration reproducibility; the low-temperature lubrication calibration time for a single engine model is reduced by 40%, eliminating a large number of repetitive bench tests.

[0023] 4. This invention relies solely on two basic signals—oil temperature and engine speed—to implement protection logic, without binding to dedicated control programs for gasoline and diesel engine fuel injection. The same underlying algorithm can be directly ported and adapted to both gasoline and diesel engines without the need to reconstruct control branches. Simultaneously, the underlying oil film protection logic can seamlessly adapt to all thin-walled sliding bearing friction pairs, such as camshaft bushings and balance shaft bearings. When adding protection for new engine models or friction pairs, there is no need to redevelop the software framework, significantly reducing the calibration and verification costs of simultaneous development across multiple product lines.

[0024] 5. This invention achieves all low-temperature protection functions solely through ECU software algorithm upgrades, requiring no additional hardware, no replacement of high-alloy thickened bearings, and no oil preheating device. After implementing this solution, engines can be downgraded to use conventional standard bearings, reducing the material cost of bearings per engine by 8-15 yuan. With an annual production scale of 100,000 units, annual material cost reductions can reach millions of yuan, without increasing the cost of antifreeze oil for end users. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a flowchart of one embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0028] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0029] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device that includes said element.

[0030] It should be noted that any symbols and / or numbers present in the specification that are not marked in the accompanying drawings are not reference numerals.

[0031] Example 1 This invention provides a low-temperature control system for engine bearings.

[0032] The main execution component of this system is the engine ECU controller, and the supporting data acquisition components and their connections are as follows: The ECU is used to implement the engine bearing low-temperature protection method. The ECU has a built-in erasable and rewritable memory unit to store the calibrated steady-state tachometer, the ramp rate table and the preset temperature threshold. The oil temperature sensor is used to communicate with the ECU's analog signal acquisition port to collect the oil temperature in the oil pan in real time. The crankshaft speed sensor is used to connect to the ECU speed acquisition channel and output the instantaneous engine speed signal.

[0033] Each sensor is only responsible for collecting raw operating condition signals; all speed limit judgments, corrections, and output logic are completed by the ECU's built-in control program.

[0034] Example 2 This invention provides a low-temperature protection calibration system for engine bearings: The main execution component of this system is the engine ECU controller, and the supporting data acquisition components and their connections are as follows: The ECU is used in the bench calibration process of the engine bearing low-temperature protection method. The ECU has a built-in erasable and rewritable memory unit for storing steady-state speed table and climb rate table. The oil temperature sensor is used to communicate with the ECU's analog signal acquisition port to collect the oil temperature in the oil pan in real time. The crankshaft speed sensor is used to connect to the ECU speed acquisition channel and output the instantaneous engine speed signal; The vibration sensor, main oil passage pressure sensor, and bearing temperature thermocouple connected to the ECU calibration port are used to acquire the engine vibration amplitude signal, the instantaneous drop signal of the main oil pressure, and the sudden change signal of the bearing temperature, respectively.

[0035] Example 3 This invention provides a method for low-temperature protection of engine bearings: Step 1: Real-time acquisition of operating condition signals After the ECU is powered on, it continuously and synchronously reads the real-time oil temperature Toil and the instantaneous engine speed n; it calculates the speed rise rate Δn / Δt according to a fixed sampling period (e.g., 10ms), where the speed rise rate = (current speed - previous cycle speed) / sampling interval.

[0036] Step 2: Look up the table to obtain the basic limit value Using oil temperature (Toil) as the query variable, retrieve two calibration tables stored in the ECU: ①Steady-state maximum permissible speed gauge: Outputs the highest steady-state speed Nmax that is allowed to run continuously at this oil temperature; ② Maximum Speed ​​Rise Rate Table: Outputs the maximum allowable speed rise rate Vmax at this oil temperature.

[0037] Step 3: Dynamic correction limit for oil temperature rise rate Adjust Nmax and Vmax according to the rate of increase of oil temperature dToil / dt: the faster the oil temperature rises, the faster the oil film is established, and adjust the upper limit of steady-state speed and the limit of the rate of increase accordingly; if the oil temperature remains flat or drops, keep the original limits from the table unchanged.

[0038] Step 4: Determine the temperature range logically and output lock / unlock commands. Two sets of thresholds are preset: low temperature lock-in threshold T1 and high temperature unlock threshold T2, where T2 > T1, and T1 and T2 constitute a temperature range (i.e., T1 is the lower limit and T2 is the upper limit). When Toil≤T1: The speed protection logic is continuously triggered, i.e., it enters the lock-up state; When Toil rises from low temperature to Toil≥T2: the speed and climb rate limits are completely released, i.e., the unlocked state is entered; When Toil is in the (T1,T2) range: maintain the control state of the previous cycle and do not frequently switch protection modes.

[0039] Once locked, the ECU executes a two-dimensional forced speed limit constraint, namely: Compare the engine's instantaneous speed n with Nmax, and the actual speed ramp rate Δn / Δt with Vmax: If n > Nmax, the ECU limits fuel injection / intake air volume to bring the engine speed back below Nmax; If Δn / Δt > Vmax, then the throttle response gradient is limited, the speed of engine speed increase is slowed down, and instantaneous rapid acceleration shock is avoided.

[0040] The aforementioned speed protection constraint logic controls the bearing impact load during the oil film establishment phase, which simultaneously acts on the crankshaft main bearing and connecting rod bearing. Furthermore, the underlying oil temperature-speed constraint logic can be adapted to similar sliding friction pairs such as camshaft bushings and balance shaft bearings without modification.

[0041] Using engine bearing low-temperature protection methods requires prior bench calibration. The bench calibration process includes: Step 1: Setting up a constant temperature environment for the test bench The oil pan is equipped with an independent temperature control fixture, with stepped extreme cold constant temperature points: -40℃, -30℃, -20℃, and -10℃. Each constant temperature point is maintained for 30 minutes to ensure uniform temperature across the entire oil surface.

[0042] Step 2: Critical Wear Boundary Sweep Test Within a single constant temperature point, the steady-state speed is gradually increased, and the speed increase rate is gradually increased; three sets of signals are collected simultaneously: sudden change in bearing temperature, instantaneous drop in main oil pressure, and vibration amplitude of the engine body. If any one of them reaches the critical threshold, the working condition is determined to be the critical boundary of dry bearing wear.

[0043] Step 3: Assigning safety margin values The steady-state speed and climb rate corresponding to the critical boundary are reduced by 10%-15% as the safe limits for steady-state speed and climb rate at that oil temperature.

[0044] Step 4: Fixed storage of calibration table The safety limits corresponding to all temperature points are entered into a two-dimensional data table to generate a steady-state speed table and a climb rate table, which are then written into the ECU storage unit to complete the calibration.

[0045] Example 4: Complete Control Example of Passenger Vehicle Gasoline Engine under Extreme Cold Conditions of -40℃ 1. Bench calibration process The constant temperature fixture stabilizes the engine oil to -40℃ and holds it at that temperature for 30 minutes. The steady-state speed and speed ramp-up rate were gradually increased through sweep point tests to determine the critical boundaries of dry grinding: the critical steady-state speed is 2200 r / min and the critical ramp-up rate is 1200 r / min / s. The safety margin was reduced by 12%, and the calibration table limits were generated as follows: steady-state maximum speed 1936 r / min, maximum climb rate 1056 r / min / s; The two sets of limits are written into the ECU storage unit.

[0046] 2. Vehicle Operation Control Process When the ECU is powered on, the oil temperature Toil is collected at -40℃, the initial instantaneous engine speed n is 0 r / min, and the computer oil temperature rise rate dToil / dt ≈ 0℃ / s; From the table, Nmax = 1936 r / min and Vmax = 1056 r / min / s are obtained; the oil temperature rises but does not increase, so the limit is not corrected. With a temperature of Toil≤T1=-25℃, dual-dimensional speed limiting protection is continuously activated. When the driver accelerates suddenly, the required rate of acceleration is 1600 r / min / s, which is greater than Vmax; the ECU limits the throttle response gradient, and the actual rate of acceleration can reach a maximum of 1056 r / min / s; the instantaneous speed does not exceed 1936 r / min. After running continuously for 15 minutes, the oil temperature rises to -17℃, reaching the unlock threshold T2, completely removing the speed and climb rate limits.

[0047] 3. Actual effect of this embodiment Cold start at -40℃ with rapid acceleration results in no dry friction and scoring of bearings, reducing wear by 92% compared to conventional single speed limiter solutions; protection is achieved solely through software logic, eliminating the need to replace bearings with high-specification ones, thus reducing the cost per bearing by 10 yuan.

[0048] Example 5: Low Temperature Condition at -22℃ Example of Dynamic Oil Temperature Rise Correction for Commercial Vehicle Diesel Engines 1. The data obtained in advance for bench calibration are: at an oil temperature of -22℃, the steady-state speed at which the critical boundary is 2600 r / min and the ramp rate is 1400 r / min / s; after reserving a 12% margin, the basic limit values ​​are Nmax=2288 r / min and Vmax=1232 r / min / s. 2. After a cold start, the engine oil heats up rapidly, with the oil temperature rise rate dToil / dt = 0.08℃ / 10ms; 3. The program dynamically adjusts the limits based on the rate of increase of engine oil temperature. After correction, Nmax = 2450 r / min and Vmax = 1350 r / min / s. 4. The oil temperature is stable at -22℃, within the temperature range (T1=-25℃—T2=-18℃), maintaining the protection state of the previous cycle, and not repeatedly switching modes; 5. It can simultaneously lubricate and protect the connecting rod bearings and balance shaft bushings of the diesel engine.

[0049] Implementation effect It balances low-temperature protection with diesel engine power response, without power lag caused by excessive speed limiting; the calibration algorithm can be directly reused to diesel engines of different displacements on the same platform without the need to redevelop the underlying logic.

[0050] Example 6: General Calibration Process Example 1. Constant temperature setting: four constant temperature levels: -40℃, -30℃, -20℃, and -10℃, with each level held for 30 minutes; 2. Three indicators for critical wear determination: instantaneous oil temperature rise in bearing bush > 8℃ / s, main oil passage oil pressure drop > 0.15MPa, and engine vibration amplitude > 0.6mm / s. Any one of these triggers indicates critical wear. 3. Collect critical parameters at each constant temperature point, uniformly reduce the safety margin by 12%, and generate a complete calibration table; 4. The calibration table can be directly flashed for gasoline and diesel engine ECUs, making it compatible with internal combustion engines in road vehicles and construction machinery.

[0051] Implementation effect The low-temperature calibration time for a single model is reduced by 40%, and the deviation of calibration results from different engineers and different batches of benches is controlled within 5%, significantly improving calibration consistency.

[0052] Comparative example: Existing conventional monostable speed limiting scheme 1. Only sets the oil temperature threshold to -25℃, limits the maximum steady-state speed to 1936r / min, and has no speed ramp-up rate constraint, no temperature range design, and no dynamic correction for oil temperature rise. 2. During rapid acceleration from a cold start at -40℃, the speed can climb at a rate of 1600 r / min / s, generating instantaneous high loads before an oil film is established; 3. Test data: Under the same working conditions, the dry wear failure rate of the bearing bush is 12.7%, and the alternating wear is 12.5 times that of the embodiment of the present invention; 4. Gasoline and diesel engine models need to be calibrated separately and cannot be extended to include balance shafts, camshaft bushings, etc.

[0053] This invention also features a power-on pre-start lock-up protection: during the vehicle's power-on but not ignition phase, if the engine oil temperature is lower than a preset ignition temperature threshold (e.g., -25°C), the maximum throttle speed request is locked in advance to avoid instantaneous impact wear caused by sudden acceleration at the moment of ignition. This is a pre-emptive protection mechanism that pre-judges the oil temperature and limits the throttle torque request before ignition.

[0054] Furthermore, when collecting engine oil temperature, the equivalent oil temperature can be calculated by multi-sensor fusion of the main oil passage oil temperature sensor or the crankcase average oil temperature; both can obtain the actual working temperature of the engine oil, thus fully realizing dual-dimensional speed limiting protection.

[0055] Furthermore, the speed ramp-up rate can be calculated by collecting speed data at a fixed 10ms cycle and performing difference calculations, or by estimating the speed ramp-up trend based on the rate of change of throttle pedal opening, or by calculating the ramp-up rate using the differential of a filtered and smoothed speed curve; all of these methods can quantify the speed increase rate and achieve ramp-up rate limit control.

[0056] Furthermore, the low-temperature locking threshold T1=-25℃ and the high-temperature unlocking threshold T2=-18℃ are universally applicable; it can also be adapted to any combination of dual thresholds in the range of T1∈[-30℃,-20℃] and T2=T1+6~10℃ according to different models.

[0057] Furthermore, when obtaining the highest steady-state speed correction value and the maximum speed climb rate correction value based on the oil temperature rise rate, the oil temperature rise correction process is either a linear proportional increase of the limit value or a segmented step correction.

[0058] Furthermore, the main ECU of the vehicle engine is generally used as the controller carrier, but an independent low-temperature lubrication protection auxiliary controller can also be set up to interact with the main ECU through the CAN bus to achieve speed limiting; the low-temperature lubrication protection auxiliary controller executes a full set of protection logic to achieve the same protection effect.

[0059] Furthermore, this invention is applicable to gasoline engines for passenger vehicles and diesel engines for commercial vehicles; it can also be applied to internal combustion engines for agricultural machinery, diesel engines for construction machinery, small and medium-sized reciprocating internal combustion engines for ships, and internal combustion engines for generator sets; only the two calibration tables for the corresponding models need to be replaced, and the underlying control logic does not need to be modified, making it compatible with all reciprocating internal combustion engines with bearing friction pairs.

[0060] Furthermore, the critical determination signal uses a combination of three signals: bearing temperature, oil pressure, and machine body vibration; alternatively, any two of these signals can be selected to determine the critical wear boundary, which can objectively identify the critical working condition of dry bearing wear and complete the standardized calibration.

[0061] Furthermore, an external independent temperature-controlled water bath fixture can be used on the oil pan; alternatively, a full-range high and low temperature environment chamber can be used to control the temperature of the engine oil in extremely cold conditions.

[0062] Furthermore, if the instantaneous engine speed exceeds the maximum steady-state speed correction value, the speed is generally controlled by limiting the fuel injection quantity and intake air quantity. Speed ​​constraints can also be achieved by limiting the electronic throttle opening, limiting the ignition advance angle, and limiting the fuel injection advance angle. All of these methods can forcibly limit the steady-state speed and speed ramp-up rate, achieving the goal of preventing dry friction at low temperatures.

[0063] Furthermore, based on the control method of this invention, a low-power oil preheating device is added as a cold start auxiliary structure. The oil base temperature is increased in advance when the engine is powered on, which further reduces the initial dry friction stress of the main bearing and connecting rod bearing. This achieves the invention's objective of reliable protection of friction pairs under extremely cold conditions while taking into account power output. It can be universally adapted to all reciprocating internal combustion engines with bearing friction pairs.

[0064] Furthermore, this invention can use coolant temperature instead of engine oil temperature: using cylinder block coolant temperature instead of engine oil temperature as the criterion for determining the low-temperature range, a calibration table of coolant temperature-steady-state speed-speed ramp-up rate is constructed; relying on coolant temperature to indirectly characterize the low-temperature lubrication conditions of the whole machine, a dual-dimensional collaborative speed limiting logic completely consistent with this invention is executed, achieving the same low-temperature wear suppression effect on main bearings and connecting rod bearings, and is compatible with various reciprocating internal combustion engines such as gasoline engines and diesel engines.

[0065] Furthermore, if the engine speed climb rate is greater than the maximum engine speed climb rate correction value, the direct limit cutoff logic for the instantaneous engine speed climb rate can be canceled. Based on the differential decay of the accelerator pedal output response slope within the oil temperature range, the speed rise gradient can be indirectly constrained by limiting the rate of change of the throttle signal.

[0066] Furthermore, the core parameters of the low-temperature safety boundary of the main bearing and connecting rod bearing have been pre-calibrated in batches on high and low temperature engine benches. Only minor dynamic correction parameters are supplemented and calibrated through vehicle cold-region road tests, ultimately generating a standardized temperature-steady-state speed-climb rate calibration table. The bottom oil temperature stratification dual-speed limit control logic remains unchanged, only the workload of bench calibration and vehicle road testing is redistributed, achieving the same extreme cold friction pair protection effect and adapting to the calibration and development process of all types of internal combustion engines.

[0067] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0068] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for low-temperature protection of engine bearings, characterized in that, Includes the following steps: S1: Real-time acquisition and calculation of operating condition signals; wherein, the operating condition signals include oil temperature and instantaneous engine speed, and the oil temperature rise rate and engine speed climb rate are calculated. S2: Based on the pre-calibrated steady-state speed table and creep rate table, obtain the highest steady-state speed and the maximum speed creep rate corresponding to the oil temperature; S3: Obtain the highest steady-state speed correction value and the maximum speed climb rate correction value based on the oil temperature rise rate; S4: Compare the engine oil temperature with the preset temperature threshold to determine whether to enter the lock or unlock state; When in the locked state, the instantaneous engine speed is compared with the correction value for the highest steady-state speed, and the speed climb rate is compared with the correction value for the maximum speed climb rate. If the instantaneous engine speed is greater than the maximum steady-state speed correction value, then the fuel injection quantity or intake air quantity is limited to reduce the speed to below the corrected maximum steady-state speed. If the engine speed climb rate is greater than the maximum engine speed climb rate correction value, then the throttle response rate is limited, and the engine speed climb rate is reduced.

2. The method for low-temperature protection of engine bearings according to claim 1, characterized in that, The step of comparing the engine oil temperature with a preset temperature threshold to determine whether to enter a locked or unlocked state specifically includes: The temperature threshold is a temperature range; When the oil temperature is less than or equal to the lower limit of the temperature range, it enters a lock-up state; When the engine oil temperature is greater than or equal to the upper limit of the temperature range, the system enters the unlocked state. When the engine oil temperature is within the specified temperature range, maintain the current state.

3. The engine bearing low-temperature protection method according to claim 1, characterized in that, The calibration process for the steady-state tachometer and the climb rate meter is as follows: The oil pan is equipped with an independent temperature control fixture, which sets multiple constant temperature points with progressively increasing temperatures, and sets a preset holding time for each constant temperature point. Within each constant temperature point, the steady-state speed and the speed increase rate are gradually increased according to preset levels. Three sets of signals are collected simultaneously: bearing temperature change signal, oil main pressure instantaneous drop signal, and engine vibration amplitude signal. If any one of the three signals reaches the corresponding critical threshold, it is determined that the bearing dry friction critical boundary has been reached. The corresponding steady-state speed and speed increase rate are reduced by a preset ratio to become the highest steady-state speed and maximum speed increase rate at that constant temperature point. The highest steady-state speed and the maximum speed increase rate corresponding to all constant temperature points are entered into a two-dimensional data table to generate a steady-state speed table and a speed increase rate table, which are then stored.

4. The engine bearing low-temperature protection method according to claim 1, characterized in that, Step S3 specifically includes: If the rate of increase in oil temperature rise increases, then the highest steady-state speed and the maximum speed rise rate obtained by S2 are adjusted upwards to obtain the correction values ​​for the highest steady-state speed and the maximum speed rise rate. If the rate of increase of engine oil temperature remains unchanged or decreases, the highest steady-state speed and the maximum speed increase rate obtained from S2 are directly used as the correction values ​​for the highest steady-state speed and the maximum speed increase rate.

5. The method for low-temperature protection of engine bearings according to claim 1, characterized in that, Before step S1, the following is also included: During the power-on but not ignition phase, the engine oil temperature is predicted; if the engine oil temperature is less than or equal to the preset ignition temperature threshold, the maximum throttle speed is locked.

6. The method for low-temperature protection of engine bearings according to claim 1, characterized in that, The operating condition signal in step S1 also includes the accelerator pedal opening. In step S4, if the speed increase rate is greater than the maximum speed increase rate correction value, then the accelerator pedal output response slope is attenuated according to the oil temperature range, and the speed increase rate is indirectly constrained by limiting the throttle signal change rate. If the indirect constraint on the speed increase rate is not effective, then the throttle response rate is limited to reduce the speed increase rate.

7. The method for low-temperature protection of engine bearings according to claim 6, characterized in that, It also includes step S5: based on the highest steady-state speed and the accelerator pedal output response slope, output the corrected fuel injection quantity and intake air quantity control signal.

8. A low-temperature protection control system for engine bearings, characterized in that, include: ECU, used to execute the engine bearing low temperature protection method according to any one of claims 1-7, the ECU has a built-in erasable and rewritable memory unit for storing the calibrated steady-state speed table, the ramp rate table and the preset temperature threshold; The oil temperature sensor is used to communicate with the ECU's analog signal acquisition port to collect the oil temperature in the oil pan in real time. The crankshaft speed sensor is used to connect to the ECU speed acquisition channel and output the instantaneous engine speed signal.

9. A low-temperature protection calibration system for engine bearings, characterized in that, include: ECU, used to execute the engine bearing low temperature protection method as described in claim 3, the ECU has a built-in erasable and rewritable memory unit for storing steady-state speed table and climb rate table; The oil temperature sensor is used to communicate with the ECU's analog signal acquisition port to collect the oil temperature in the oil pan in real time. The crankshaft speed sensor is used to connect to the ECU speed acquisition channel and output the instantaneous engine speed signal; The vibration sensor, main oil passage pressure sensor, and bearing temperature thermocouple connected to the ECU calibration port are used to acquire the engine vibration amplitude signal, the instantaneous drop signal of the main oil pressure, and the sudden change signal of the bearing temperature, respectively.

10. A vehicle, characterized in that, Including the engine bearing low-temperature protection control system as described in claim 8.

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