Differential Score Protection via Engine Speed Limits
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Solution Overview
Problem
Traditional differential score protection (DSP) control systems are time and cost intensive due to the need for calibration based on various ΔRPM values, and the calibration parameters must be translated across different control module types, leading to inefficiencies and increased costs in preventing differential damage from excessive wheel speed differences.
Innovation Solution
A differential score protection system that includes modules to initiate a DSP mode based on pre-determined engine speed limits, decreasing engine speed at a fixed rate when wheel slip differentials exceed thresholds, and using sensors to monitor wheel and transmission output shaft speeds, eliminating the need for complex calibration across different control modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional DSP control regulates engine torque output based on calibrated ΔRPM values, then wheel slip condition is resolved and differential damage is prevented, but calibration process is time and cost intensive and must be translated across multiple control module types
Solution Approach 1:
The patent changes the control parameter from calibrated torque reduction values (X Nm) to engine speed limits (RPM thresholds). This parameter change eliminates the need for complex calibration across different control modules, as the engine speed limits are directly derived from the differential's design slip speed limit and transmission gear ratios, making the system universally applicable without module-specific calibration translation.
Solution Approach 2:
The patent establishes pre-determined engine speed limits based on the differential's design slip speed limit before operation. By calculating these limits in advance using the formula: engine speed limit = differential slip speed limit × transmission gear ratio, the system eliminates the need for time-consuming calibration processes during vehicle development and deployment.
2Reliability
If traditional DSP control decreases engine torque to reduce power output, then wheel slip is resolved, but vehicle operator perceives excessive power sags or surges
Solution Approach 1:
The patent implements dynamic engine speed limiting where the engine control module continuously monitors engine speed and compares it against the pre-determined engine speed limit. When the engine speed exceeds the limit, the system dynamically adjusts the maximum engine speed threshold, allowing for smooth, progressive torque reduction rather than abrupt torque cuts, thereby maintaining drivability while preventing wheel slip.
3Adaptability or versatility
If calibration parameters are translated for various control module types, then compatibility across manufacturers is achieved, but the calibration process is compounded and costs increase
Solution Approach 1:
The patent creates a universal control approach where a single set of engine speed limits can be applied across all control module types and manufacturers. The engine speed limit calculation based on differential slip speed limit and transmission gear ratio is independent of control module specifics, making the system universally applicable without requiring calibration translation or adaptation for different module types.
Data Source
AI summary
A differential score protection system that regulates an engine to inhibit damage to a differential driven by the engine includes a first module that initiates a differential score protection mode and a second module that decreases an engine speed when the engine speed exceeds an engine speed limit. The engine speed limit is one of a plurality of pre-determined values based on a design slip speed limit of the differential.