Active Engine Mount Diagnostics via Controlled Vibration
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Solution Overview
Problem
Active engine mounts in vehicles may not function as desired, leading to undesired noise, vibration, and harshness (NVH), which can go unnoticed, especially in autonomous vehicles, potentially causing complications. Current methods lack a systematic way to diagnose the functionality of these mounts periodically, especially under conditions where a vehicle operator is not present.
Innovation Solution
A method involving controlling active engine mounts to switch between dampening and stiffening modes, inducing degraded combustion in a selected engine cylinder, and monitoring vibrations using sensors to determine if the mounts are functioning correctly, indicating issues if vibrations exceed or fail to meet threshold levels during specific mode operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If active engine mounts are used to isolate engine vibration, then NVH performance is improved, but the ability to detect mount functionality deteriorates
Solution Approach 1:
The system performs preliminary diagnostic actions by inducing controlled degraded combustion events before they occur during normal operation. The ECU proactively creates test conditions by cutting fuel to specific cylinders, allowing the system to assess mount functionality in advance rather than waiting for failure symptoms to manifest.
Solution Approach 2:
The system uses mechanical vibration as a diagnostic tool by inducing controlled vibrations through degraded combustion events. The active engine mounts respond to these known vibration inputs, and sensors measure the resulting vibrations to determine whether the mounts are functioning correctly. This transforms vibration from a harmful factor into a useful diagnostic signal.
2Measurement precision
If degraded combustion events are induced to diagnose active engine mounts, then diagnostic capability is improved, but engine performance deteriorates
Solution Approach 1:
The system implements periodic diagnostic action by conducting degraded combustion events only at specific intervals and under predetermined conditions (e.g., during idle or low-load operation). The ECU selectively applies fuel cuts to certain cylinders only when diagnostic assessment is needed, rather than continuously, thereby maintaining engine performance during normal operation while enabling periodic health checks.
Solution Approach 2:
The system applies partial action by inducing degraded combustion in only one or selected cylinders rather than all cylinders simultaneously. This allows diagnostic information to be obtained from specific mount responses while minimizing the impact on overall engine performance and power output.
3Adaptability or versatility
If active engine mounts are controlled to multiple modes, then adaptability is improved, but device complexity increases
Solution Approach 1:
The active engine mount system performs multiple functions: it actively controls vibration isolation in different modes during normal operation, and simultaneously serves as a diagnostic test subject for assessing its own functionality. The same control system that manages the mounts' operational modes also orchestrates the diagnostic procedures, eliminating the need for separate diagnostic hardware and reducing overall system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for periodic diagnosis of active engine mounts, preventing complications by identifying if they are stuck in either mode, ensuring they operate as intended, even in autonomous vehicle scenarios where NVH issues might not be immediately recognized.
Implementation Method 1
isolating engine vibration from a cabin and chassis of the vehicle via one or more active engine mounts
Implementation Method 2
inducing degraded combustion in a preselected engine cylinder
Data Source
AI summary
Methods and systems are provided for diagnosing whether active engine mounts configured to isolate engine vibration from a cabin and chassis of a vehicle are functioning as desired. In one example, engine vibrations are actively induced, and the active engine mounts are alternately controlled to a first, dampening mode, and to a second, stiffening mode for predetermined time periods, where resultant chassis vibrations are monitored during the predetermined time periods. By monitoring chassis vibrations as a function of induced engine vibrations, and further responsive to the active engine mounts being controlled to the first and second modes, it may be indicated as to whether the active engine mounts are functioning as desired.