Vehicle Speed Limiter for Drive-by-Wire Throttle Systems
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Solution Overview
Problem
Existing speed limiter systems for vehicles with 'drive-by-wire' throttle systems are complex and require extensive modifications to engine management systems, which is unnecessary for simple speed limiting and can cause compatibility issues, especially in vehicles with complex engine management systems.
Innovation Solution
A vehicle speed limiter system that includes a mechanically actuatable throttle member, a throttle signal unit, a vehicle speed sensor, a limit speed data register, a comparator, and a throttle signal modifier unit that modifies the throttle signal to limit engine speed without interacting directly with the engine management system, allowing for simple and effective speed limiting without complex modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a speed limiter system is integrated into a vehicle with drive-by-wire throttle system, then speed limiting function is achieved, but the system complexity increases and requires extensive modifications to engine management systems
Solution Approach 1:
The patent introduces a speed limiter control unit as an intermediary component that sits between the existing throttle control system and engine management system. This control unit receives speed signals from vehicle sensors, compares them against predetermined limits, and generates appropriate control signals without requiring modifications to the existing engine management system architecture. The intermediary approach allows speed limiting functionality to be added while maintaining system independence and avoiding complex integrations.
2Speed
If a speed limiter system modifies the throttle signal directly, then speed limiting is achieved, but compatibility issues arise with complex engine management systems and may cause malfunctions
Solution Approach 1:
The patent segments the speed limiting function into a separate, independent control unit that operates autonomously from the engine management system. The speed limiter control unit handles speed signal processing and limit enforcement independently, then outputs control signals that work with the existing throttle actuator. This segmentation prevents compatibility conflicts by isolating the speed limiting logic from the complex engine management electronics, allowing both systems to operate without interfering with each other's proprietary protocols and control algorithms.
3Adaptability or versatility
If existing speed limiter systems are integrated into drive-by-wire vehicles, then speed limiting capability is provided, but extensive modifications to engine management systems are required
Solution Approach 1:
The speed limiter control unit is designed as a self-contained module that performs all necessary functions internally - receiving speed signals from standard vehicle sensors, processing the signals through predetermined limit comparisons, and generating control outputs to the throttle actuator. The unit operates autonomously using its own embedded logic and does not require integration with or modifications to the vehicle's existing engine management computer. This self-service design allows the speed limiter to be manufactured and installed as a standalone component, significantly reducing integration complexity and manufacturing overhead.
Data Source
Figure 1
AI summary
A vehicle speed limiter is described, for use with, and for example fitted to, a vehicle throttle system (1) comprising a mechanically actuatable throttle member (3), an engine (10) speed controller (7), and a throttle signal unit in data communication with an engine speed controller and operably coupled to the throttle member so as to generate an electronic throttle signal in functional response to the degree of actuation of the throttle member, and to transmit a throttle signal to the engine speed controller whereby the engine speed is controlled. The speed limiter has a vehicle speed sensor (15) to obtain a signal indicative of vehicle speed; a limit speed data register to include a data store (17) for a data item indicative of at least a first predetermined limit speed; a comparator to compare the speed sensor output with the limit speed data item stored in the limit speed register; a throttle signal modifier unit acting on the output of a throttle signal unit in use when fitted in conjunction with a vehicle throttle system to modify a generated throttle signal so that a transmitted throttle signal is produced such as to tend to limit the vehicle to the applied limit speed. A method of fitment is also described.