Control method for reducing abnormal sound of engine

Abstract

The invention discloses a control method for reducing abnormal sound of an engine, which comprises the following steps of: acquiring a basic working point with minimum frictional resistance and minimum vibration when the engine is started by testing vibration noise data of a hybrid power assembly during starting and flameout; vibration characteristics in the engine starting and flameout process are analyzed through rack calibration data, and vibration characteristics of an output end under different temperature curves during engine starting and flameout are drawn; the output suppression torque of the starting motor is calculated through an intelligent algorithm, relatively prominent vibration generated in the starting or flameout process of the engine is eliminated or weakened through torque regulation and control, and noise is effectively reduced. By the adoption of the technical scheme, abnormal sound generated when the hybrid engine is started and shut down is improved, and the NVH level of the whole vehicle is effectively improved; the rotating speed of the engine is monitored in real time to recognize the working state of the engine, correction torque is accumulated on a motor restraining torque curve, torque output of the motor and the engine is intelligently adjusted, and impact during starting and flameout is avoided.

Description

Technical Field

[0001] This invention belongs to the technical field of hybrid vehicle control. More specifically, this invention relates to a control method for reducing abnormal engine noise. Background Technology

[0002] As automobiles evolve towards electrification and intelligence, hybrid vehicles have gradually become the mainstream in the market. Compared to traditional gasoline vehicles, hybrid powertrains introduce new components such as electric motors and electronic controls, altering the operating mode of the internal combustion engine. This makes their NVH (noise, vibration, and harshness) characteristics exceptionally complex. The key challenges in hybrid powertrain development stem primarily from the high complexity of the hybrid system, the introduction of new components, the diversity of operating modes, and the changes in NVH characteristics. While hybrid vehicles are becoming increasingly popular due to their energy-saving and environmentally friendly characteristics, their noise, vibration, and harshness (NVH) issues have become a core challenge in their development. Compared to traditional vehicles, the NVH performance of hybrid powertrains is more complex, directly impacting driving comfort and user experience.

[0003] To improve thermal efficiency, hybrid engines often employ combustion cycles with high compression and expansion ratios, such as the Miller cycle. In this combustion cycle, flame propagation is faster and the ignition delay is shorter. Therefore, Miller combustion produces higher peak combustion pressures and a higher rate of pressure rise (especially under partial load conditions). Experimental data shows that Miller combustion is faster (especially during the first 50% of fuel combustion heat release), thus its peak pressure tends to be earlier and more pronounced, with a larger variation in the rate of pressure rise. These combustion characteristics increase the high-frequency components of the combustion wave, resulting in higher noise levels and a sharper sound. Regarding the start-stop mechanism of hybrid engines compared to conventional engines, the biggest difference lies in the fact that the starting speed of a hybrid engine is much higher than that of a conventional starter motor. Compared to conventional engines, hybrid engines often start at higher speeds, resulting in a more pronounced torsional shock. Dual-motor + engine hybrid systems, as a common hybrid architecture, use the starter motor to assist in engine starting.

[0004] Hybrid-specific engines are a key development direction for new energy vehicles. Unlike traditional engines, due to increasingly stringent emission and fuel consumption regulations, their mechanical structure and operating conditions are very different from those of traditional engines.

[0005] When a vehicle is running at medium to high speeds, the engine in the hybrid powertrain is activated and often operates at medium to high speeds and loads. At this time, the vehicle switches from the very quiet EV mode to the HEV mode. Without the masking effect of a traditional engine, users are more sensitive to the noise of the vehicle and have a poor experience.

[0006] To address the various challenges faced by hybrid-specific engines in terms of noise and acoustics, the NVH performance of hybrid-specific engines is often improved by enhancing the engine's mechanical properties, the connection structure of the transmission system, and the system architecture. However, this approach is often costly and yields limited results, resulting in a bottleneck in NVH performance improvement.

[0007] Therefore, the abnormal noises generated when the hybrid engine starts and stops have always been a challenge in the development of NVH for new energy vehicles.

[0008] Deficiencies of existing technology:

[0009] 1. Existing PHEV models have eliminated the low-voltage starter motor found in traditional engines, instead using a high-voltage generator on the hybrid transmission to ignite the engine. Power is transmitted between the engine and the generator via two sets of constantly meshing gears, resulting in a gap in the power transmission path—a characteristic of gear drives.

[0010] 2. The PHEV vehicle experiences severe vibrations during startup (engine ignition) and when the engine engages while driving, accompanied by a "clunking" sound during startup. There are more than two vibration impacts during the vibration process, and the vibration decays slowly with a long decay time, resulting in a very poor subjective experience.

[0011] 3. Current technology primarily focuses on improving the precision of parts and components, reducing design clearances, minimizing impact, and lowering noise and vibration. Improving NVH performance through gear and bearing design has reached a bottleneck; further improvements are costly and yield limited results.

[0012] Using keywords such as "improve; overcome; engine abnormal noise", a search was conducted on existing publicly available technical documents, and the following search results were obtained:

[0013] 1. Chinese patent document: "A method for identifying abnormal engine noise and related equipment", patent (application) number: 202110796048.8; the technical solution described therein is:

[0014] "An engine abnormal noise identification method and related equipment, the method comprising: after acquiring a sound signal to be identified, firstly extracting at least one audio data to be used from the sound signal to be identified according to a preset window parameter; then performing feature extraction on the at least one audio data to be used respectively to obtain at least one audio feature to be used; finally, determining the abnormal noise identification result of the sound signal to be identified based on the at least one audio feature to be used and a pre-built abnormal noise identification model, so that the abnormal noise identification result can accurately indicate whether there is an abnormal noise in the sound signal to be identified"

[0015] The technical effects described are:

[0016] "It can overcome the shortcomings of avoiding manual identification of engine abnormal noise as much as possible, thereby improving the accuracy of engine abnormal noise identification, which in turn helps to improve the accuracy of vehicle fault diagnosis."

[0017] 2. Chinese patent document: "Solution, Device, Equipment, Storage Medium and Computer Product for Engine Shutdown Noise", Patent (Application) No.: 202411263537.7; the technical solution described therein is:

[0018] "The solution to the abnormal noise when the engine is turned off includes the following steps: when the vehicle is in the off mode, obtain the minimum opening of the throttle valve when the engine does not make abnormal noise; detect the engine speed and the current throttle valve opening in real time; when the engine speed is greater than the preset speed, control the current opening of the throttle valve to be greater than the minimum opening."

[0019] The technical effects described are:

[0020] "This technology effectively addresses the problem of abnormal engine noise caused by the throttle valve reaching its minimum opening prematurely when the engine is not completely shut down, resulting in fluctuating intake resistance."

[0021] However, the technical solutions recorded in the aforementioned technical documents, as well as the existing publicly available technical solutions, have not been able to solve the problems and defects in the existing technology, such as "long vibration decay time", "slow convergence speed of vibration and abnormal noise" and "extremely poor subjective feeling and driving comfort". Summary of the Invention

[0022] This invention provides a control method for reducing engine noise. Its purpose is to improve the noise problem caused by tooth surface knocking through control strategies and solve the impact of hybrid engine start-up or shutdown on the NVH of the whole vehicle.

[0023] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0024] The present invention discloses a control method for reducing engine noise, applicable to hybrid electric vehicles. The hybrid electric vehicle includes an engine and engine controller, a drive motor and motor controller, and a hybrid controller. The control method involves: obtaining the operating point with minimal frictional resistance and vibration during engine start-up by testing vibration and noise data of the hybrid powertrain during start-up and shutdown; using this operating point as the baseline operating point; analyzing bench calibration data to plot the vibration characteristics of the engine output during start-up and shutdown at different temperature curves; calculating the starter motor output suppression torque using an intelligent algorithm; and using torque regulation to eliminate or reduce prominent vibrations during engine start-up and shutdown, effectively reducing abnormal noises caused by gear knocking in the transmission system.

[0025] The control method described above analyzes the generator speed data collected by the motor controller and uses the speed data to identify the engine's start-up or shutdown status and the progress of its actual working state.

[0026] The control method described above achieves fine control of torque and speed through motor torque compensation, thereby eliminating the inertial force generated by the crankshaft when the engine starts or stops, and reducing impact.

[0027] When the engine starts, the control method replaces the step torque with a gradually increasing torque to achieve a smooth torque transition, reduce transmission system impact, and avoid large impact noise generation.

[0028] When the engine is turned off, the control method described above also ensures a smooth torque transition, reduces impact and noise, and at the same time, the precise positioning of the motor resolver ensures that the engine stops at the optimal comfort point, preparing the best conditions for the next engine start, namely low frictional resistance and low vibration.

[0029] The control method determines the actual working process by using the basic vibration characteristic curve and the real-time generator speed. It compensates for and suppresses the vibration generated by the engine in real time through the generator torque, and suppresses the noise generated during engine start-up or shutdown in advance, thereby improving the NVH performance of the whole vehicle.

[0030] The control method described above also incorporates the anti-vibration torque of the motor, further optimizing the torque of the transmission system, achieving a smooth torque transition throughout the process, and improving NVH performance.

[0031] The engine controller and the motor controller are respectively connected to the hybrid controller via communication signals.

[0032] The control method described above uses intelligent calculations to convert the engine vibration curve into a motor suppression torque curve.

[0033] This invention adopts the above-mentioned technical solution. Through software control strategies, it makes reasonable use of the characteristics of rapid motor control response and precise torque control in the system architecture to improve the abnormal noise generated by the hybrid engine during start-up and shutdown in a low-cost manner, effectively improving the NVH level of the whole vehicle. It monitors the engine speed in real time to identify the engine's working status, accumulates and corrects the torque on the motor suppression torque curve, and intelligently adjusts the torque output of the motor and the engine to avoid the impact during start-up and shutdown, thereby reducing noise. Attached Figure Description

[0034] The following is a brief description of the content shown in the attached diagram:

[0035] Figure 1 This is a block diagram of the power structure functional modules and control relationships of the present invention. Detailed Implementation

[0036] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, so as to help those skilled in the art to have a more complete, accurate and in-depth understanding of the inventive concept and technical solution of the present invention.

[0037] like Figure 1 The technical solution of the present invention shown is a control method for reducing engine noise, applied to hybrid electric vehicles (PHEVs). The PHEV includes an engine and engine controller (ECU), a drive motor and motor controller (MCU), and a hybrid control unit (HCU). The present invention relates to PHEV engine, generator, gear mechanism, and dual-mass flywheel.

[0038] To address the problems and shortcomings of existing technologies, and to achieve the goal of improving the abnormal noise caused by tooth surface knocking through control strategies, and to resolve the impact of hybrid engine start-up or shutdown on the overall vehicle NVH, the technical solution adopted by this invention is as follows:

[0039] Engines of the same model have the same vibration characteristics when operating. For example... Figure 1 As shown, the control method for reducing engine noise of the present invention obtains the operating point where the frictional resistance and vibration are minimal when the engine starts by testing the vibration and noise data of the hybrid powertrain during startup and shutdown.

[0040] The above is used to determine the starting comfort point of this engine, and this operating point is used as the base operating point.

[0041] The vibration characteristics during engine start-up and shutdown were analyzed using bench calibration data to plot the vibration characteristics of the output end during engine start-up and shutdown at different temperatures.

[0042] The intelligent algorithm calculates the suppression torque output of the starter motor, and the torque regulation is used to eliminate or reduce the prominent vibrations generated during engine start-up or shutdown, effectively reducing the "clicking" noise caused by gear knocking in the transmission system.

[0043] This invention improves the abnormal noise caused by tooth surface knocking through control strategies, and solves the impact of hybrid engine start-up or shutdown on the NVH of the whole vehicle. It has the advantages of low cost, stable performance, and effective improvement of vehicle driving comfort and user experience.

[0044] By controlling the vibration at the source, the vibration generated when starting the engine is minimized, which has the least impact on the entire transmission system and also avoids resonance with other parts of the system.

[0045] Based on project development data, the above can reduce engine cylinder pressure by approximately 60% and vibration by approximately 90% during engine startup.

[0046] The beneficial technical effects achieved by this invention are as follows:

[0047] This invention focuses on using software control strategies to make good use of the characteristics of rapid motor control response and precise torque control in the system architecture, so as to improve the abnormal noise generated by the hybrid engine during start-up and shutdown in a low-cost solution, and effectively improve the NVH level of the whole vehicle.

[0048] The specific technical solution is as follows:

[0049] The control method described above analyzes the generator speed data collected by the motor controller (MCU) and uses the speed data to identify the engine's start-up or shutdown status and the progress of its actual working state.

[0050] The control method described above achieves fine control of torque and speed through motor torque compensation, thereby eliminating the inertial force generated by the crankshaft when the engine starts or stops, and reducing impact.

[0051] Employs fine torque control that gradually increases or decreases:

[0052] When the engine starts, the control method replaces the step torque with a gradually increasing torque to achieve a smooth torque transition, reduce transmission system impact, and avoid large impact noise generation.

[0053] When the engine is turned off, the control method described above also ensures a smooth torque transition, reduces impact and noise, and at the same time, the precise positioning of the motor resolver ensures that the engine stops at the optimal comfort point, preparing the best conditions for the next engine start, namely low frictional resistance and low vibration.

[0054] The control method determines the actual working process by using the basic vibration characteristic curve and the real-time generator speed. It compensates for and suppresses the vibration generated by the engine in real time through the generator torque, and suppresses the noise generated during engine start-up or shutdown in advance, thereby improving the NVH performance of the whole vehicle.

[0055] The control method described above also incorporates the anti-vibration torque of the motor, further optimizing the torque of the transmission system, achieving a smooth torque transition throughout the process, and improving NVH performance.

[0056] The engine controller (ECU) and motor controller (MCU) are respectively connected to the hybrid controller (HCU) via communication signals.

[0057] The control method described above uses intelligent calculations to convert the engine vibration curve into a motor suppression torque curve.

[0058] In summary, this invention is an important and cost-effective method for optimizing NVH performance based on software control strategies. It makes good use of the precise torque control characteristics of the electric motor in existing hybrid vehicles and uses control logic to achieve fine control of engine start-up or shutdown.

[0059] Technical features of the present invention:

[0060] 1. Engine comfort point calibration: By analyzing the vibration and noise data of the engine during startup and shutdown through bench testing, the operating point where the frictional resistance is minimal and the vibration is lowest during engine startup was obtained; the starting point of engine startup and the stopping point of engine shutdown were confirmed through the above methods.

[0061] 2. Vibration characteristic acquisition: After determining the engine's comfort point, the engine's vibration characteristic curve is acquired;

[0062] 3. Calculate the motor suppression torque curve based on the engine's vibration characteristics and input it to the motor controller;

[0063] 4. Real-time monitoring of engine speed identifies the engine's operating status, accumulates and corrects torque on the motor's torque suppression curve, and intelligently adjusts the torque output of the motor and engine to avoid shocks during start-up and shutdown, reduce noise, and improve NVH.

[0064] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of the present invention, or the direct application of the inventive concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A control method for reducing engine noise, applied to a hybrid electric vehicle, wherein the hybrid electric vehicle includes an engine and an engine controller (ECU), a drive motor and a motor controller (MCU), and a hybrid control unit (HCU); characterized in that, The control method described is as follows: by testing the vibration and noise data of the hybrid powertrain during startup and shutdown, the operating point with the least frictional resistance and vibration during engine startup is obtained; this operating point is used as the base operating point; the vibration characteristics of the engine during startup and shutdown are plotted by analyzing bench calibration data to obtain the vibration characteristics of the output end of the engine during startup and shutdown under different temperature curves; the output suppression torque of the starter motor is calculated by intelligent algorithm, and the torque is adjusted to eliminate or reduce the prominent vibrations generated during engine startup or shutdown, effectively reducing the abnormal noise generated by gear knocking in the transmission system.

2. The control method for reducing engine abnormal noise according to claim 1, characterized in that: The control method described above analyzes the generator speed data collected by the motor controller (MCU) and uses the speed data to identify the engine's start-up or shutdown status and the progress of its actual working state.

3. The control method for reducing engine abnormal noise according to claim 2, characterized in that: The control method described above achieves fine control of torque and speed through motor torque compensation, thereby eliminating the inertial force generated by the crankshaft when the engine starts or stops, and reducing impact.

4. The control method for reducing engine abnormal noise according to claim 1, characterized in that: When the engine starts, the control method replaces the step torque with a gradually increasing torque to achieve a smooth torque transition, reduce transmission system impact, and avoid large impact noise generation.

5. The control method for reducing engine abnormal noise according to claim 1, characterized in that: When the engine is turned off, the control method described above also ensures a smooth torque transition, reduces impact and noise, and at the same time, the precise positioning of the motor resolver ensures that the engine stops at the optimal comfort point, preparing the best conditions for the next engine start, namely low frictional resistance and low vibration.

6. The control method for reducing engine abnormal noise according to claim 1, characterized in that: The control method determines the actual working process by using the basic vibration characteristic curve and the real-time generator speed. It compensates for and suppresses the vibration generated by the engine in real time through the generator torque, and suppresses the noise generated during engine start-up or shutdown in advance, thereby improving the NVH performance of the whole vehicle.

7. The control method for reducing engine abnormal noise according to claim 6, characterized in that: The control method described above also incorporates the anti-vibration torque of the motor, further optimizing the torque of the transmission system, achieving a smooth torque transition throughout the process, and improving NVH performance.

8. The control method for reducing engine abnormal noise according to claim 1, characterized in that: The engine controller (ECU) and motor controller (MCU) are respectively connected to the hybrid controller (HCU) via communication signals.

9. The control method for reducing engine abnormal noise according to claim 1, characterized in that: The control method described above uses intelligent calculations to convert the engine vibration curve into a motor suppression torque curve.

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