Vehicle Power Path Blocking Using Relay-Block Unit Timing
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Solution Overview
Problem
Existing load circuits face challenges in appropriately blocking power paths at low current values, leading to potential relay smoking, and increasing the size of both the fuse and relay to accommodate larger currents is necessary.
Innovation Solution
An on-vehicle control device employs a relay and a block unit with distinct blocking characteristics, where the relay is prioritized for low currents and the block unit for higher currents, using a first and second blocking characteristic with varying time decreases based on current values, allowing a larger current to flow without increasing relay size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the relay is blocked on the basis of a predetermined blocking characteristic to block the power path appropriately at low current values, then blocking reliability is improved, but both the fuse and relay must be increased in size to allow larger current to flow
Solution Approach 1:
The patent divides the blocking function into two segments: a block unit that blocks the power path at low current values, and a relay that blocks at high current values. This segmentation allows each component to be optimized for its specific operating range, enabling the relay to be smaller while maintaining overall system reliability.
Solution Approach 2:
The patent changes the blocking characteristic parameters by introducing a dual-characteristic system where the block unit operates with one blocking characteristic and the relay operates with another. This parameter differentiation allows the relay to be sized for high-current protection only, reducing its size while maintaining protection reliability across all current ranges.
2Quantity of substance
If the fuse is selected based on a maximum value of current to allow larger current to flow, then current capacity is improved, but blocking cannot be appropriately performed at low current values causing relay smoking
Solution Approach 1:
The block unit acts as an intermediary component that handles low-current blocking operations, allowing the fuse to be selected based on maximum current capacity without compromising low-current protection. The block unit mediates between the fuse and relay, ensuring appropriate blocking at all current levels.
Solution Approach 2:
The patent replaces the traditional mechanical relay-based blocking system with a hybrid system that uses a block unit for low-current operations and reserves the relay for high-current operations only. This substitution allows the fuse to be optimized for maximum current capacity while maintaining appropriate blocking characteristics.
Data Source
AI summary
An on-vehicle control device (1) includes a control unit (14). The control unit (14) switches a block unit (11) to a blocking state based on a first blocking characteristic (BC1). A relay (10) is turned off based on a second blocking characteristic (BC2). In the second blocking characteristic (BC2), a time decreases with a first degree of decrease as a current value increases. In the first blocking characteristic (BC1), a time decreases with a second degree of decrease in a first current value range (R1) as the current value increases, and a time decreases with a third degree of decrease in a second current value range (R2) as the current value increases. The time is set to be longer in the first blocking characteristic (BC1) than in the second blocking characteristic (BC2) for the current value smaller than a threshold (Ith). The time is set to be shorter in the first blocking characteristic (BC1) than in the second blocking characteristic (BC2) for a current value larger than the threshold (Ith).