Downshift Control for Downhill Engine Speed and Brake Wear
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Solution Overview
Problem
Heavy vehicles face challenges in controlling engine speed while driving downhill, leading to excessive speed and increased reliance on service brakes, which can cause wear and reduce longevity.
Innovation Solution
A computer system that determines the utilization rate of service brakes and, if exceeding a threshold, controls a downshift to increase auxiliary brake power, thereby reducing service brake use and optimizing brake wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If service brakes are used to control vehicle speed downhill, then vehicle speed can be controlled, but service brake wear increases and longevity decreases
Solution Approach 1:
The patent introduces auxiliary brakes as an intermediary component between the vehicle's braking system and the service brakes. The auxiliary brakes handle the primary speed control function downhill, allowing service brakes to be used less frequently and only when necessary, thereby reducing wear and extending their longevity while maintaining effective speed control.
Solution Approach 2:
The braking system is segmented into two distinct components: auxiliary brakes for primary speed control and service brakes for supplementary braking. This segmentation allows each component to perform its specific function optimally, with auxiliary brakes handling the majority of braking demands downhill and service brakes providing additional braking power only when the auxiliary brakes are insufficient.
2Reliability
If auxiliary brakes are used to control vehicle speed downhill, then service brake wear is reduced, but auxiliary brake power is insufficient at higher gears
Solution Approach 1:
The system dynamically adjusts gear selection based on real-time assessment of auxiliary brake power sufficiency. When the vehicle is in a higher gear and auxiliary brake power is determined to be insufficient for safe speed control, the system automatically selects a lower gear where the auxiliary brakes have adequate power. This dynamic adaptation ensures optimal use of auxiliary brakes while maintaining safety.
Solution Approach 2:
The control system continuously monitors vehicle parameters including speed, gear position, and auxiliary brake performance. Based on this feedback, the system determines whether auxiliary brake power is sufficient for the current operating conditions. When insufficiency is detected, the system responds by selecting an appropriate lower gear to increase auxiliary brake power availability, creating a closed-loop control system that adapts to changing conditions.
3Power
If downshift is performed to increase auxiliary brake power, then auxiliary brake power increases, but vehicle speed may decrease
Solution Approach 1:
The system performs preliminary assessment of auxiliary brake power sufficiency before executing a downshift. By evaluating current vehicle parameters and predicting future braking demands, the system determines in advance whether a downshift is necessary. This preliminary action allows for proactive gear selection that prevents speed loss while ensuring adequate auxiliary brake power is available when needed.
Solution Approach 2:
The system changes the gear parameter from a higher gear to a lower gear to increase auxiliary brake power. This parameter change is executed only when the system determines that auxiliary brake power is insufficient for safe speed control. The gear change modifies the mechanical advantage and torque characteristics, thereby increasing the effective braking power available from the auxiliary brakes without unnecessarily affecting vehicle speed.
Data Source
AI summary
A computer system, comprising processing circuitry configured to: determine that an auxiliary brake power is insufficient to prevent a vehicle running along a downhill road segment from exceeding a maximum engine speed, determine a utilization rate of one or more service brakes of the vehicle to prevent the vehicle from exceeding the maximum engine speed along the downhill road segment, determine that the utilization rate exceeds a predetermined threshold, and based on the utilization rate exceeding the predetermined threshold, control a downshift of the vehicle to increase the auxiliary brake power.