Vehicle Power Path Blocking Using Relay-Block Unit Coordination
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Solution Overview
Problem
Existing load circuits struggle to block power paths effectively at low current values without increasing the size of relays and fuses, leading to potential relay smoking and the need for larger components.
Innovation Solution
Implementing a control device with a relay and a block unit that employs distinct blocking characteristics based on current values, prioritizing relay blocking at low currents and block unit blocking at higher currents, using a mechanical relay and a semiconductor switching element, respectively, to manage current flow without enlarging the relay.
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 performance is improved, but both the fuse and the relay must be increased in size to allow larger current to flow
Solution Approach 1:
The patent divides the blocking function into two separate components: a relay for low-current blocking and a fuse for high-current blocking. This segmentation allows each component to be optimized for its specific current range, enabling the relay to be smaller while maintaining effective blocking performance at low currents, and the fuse to handle larger currents without requiring the relay to be oversized.
Solution Approach 2:
The patent changes the blocking characteristic parameters by implementing different blocking thresholds for the relay and fuse. The relay is configured with a first blocking characteristic for low current values, while the fuse provides a second blocking characteristic for high current values. This parameter differentiation allows the system to achieve reliable blocking across the full current range without increasing relay size.
2Quantity of substance
If a 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 patent segments the current protection function into two distinct ranges: the relay handles low-current blocking with a first blocking characteristic, while the fuse handles high-current blocking with a second blocking characteristic. This segmentation enables the fuse to be selected for maximum current capacity without compromising low-current blocking performance, as the relay handles that function separately.
Solution Approach 2:
The relay acts as an intermediary component that handles low-current blocking before the fuse is engaged. By introducing this intermediate blocking stage, the system can use a fuse rated for high current capacity while preventing the relay from being exposed to currents that would cause smoking or failure.
3Quantity of substance
If both the fuse and relay are increased in size to allow larger current to flow, then current capacity is improved, but device complexity and cost increase
Solution Approach 1:
By segmenting the current protection into two functional ranges handled by different components, the patent avoids the need to uniformly increase the size of both relay and fuse. The relay remains optimized for low-current operations, and the fuse is optimized for high-current operations, maintaining overall system simplicity while achieving the desired current capacity.
Data Source
AI summary
An on-vehicle control device includes a control unit switching a block unit to a blocking state based on a first blocking characteristic. A relay is turned off based on a second blocking characteristic, wherein a time decreases with a first degree of decrease as a current value increases. In the first blocking characteristic, a time decreases with a second degree of decrease in a first current value range as the current value increases, and a time decreases with a third degree of decrease in a second current value range as the current value increases. The time is set to be longer in the first blocking characteristic than in the second blocking characteristic for the current value smaller than a threshold. The time is set to be shorter in the first blocking characteristic than in the second blocking characteristic for a current value larger than the threshold.