Vehicle Blower Cut-Off Circuit Eliminates Dark Current
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Solution Overview
Problem
Existing vehicle blower apparatuses continue to draw current after the ignition switch is turned off, causing 'dark current' and potentially draining the battery, as they attempt to cool the engine or battery even after the engine has stopped, leading to incomplete power cutoff.
Innovation Solution
A blower apparatus with a microprocessor-controlled cut-off circuit that supplies power to the motor and microprocessor even after the ignition switch is off, allowing continued operation based on thermal conditions, and then completely cuts off power when necessary to eliminate dark current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the blower apparatus continues to operate after the ignition switch is turned off to cool the engine or battery, then the cooling function is maintained, but dark current flows and the battery may be drained
Solution Approach 1:
The control circuit is designed to automatically cut off power supply after a predetermined period following ignition switch-off, without requiring continuous monitoring or user intervention. This preliminary automated action prevents dark current while maintaining necessary cooling function during the critical post-shutdown period.
Solution Approach 2:
The system incorporates a timing mechanism that provides feedback control by automatically cutting off power after a predetermined period. This closed-loop approach ensures the blower operates only when necessary for cooling and stops automatically, preventing unnecessary battery drain while maintaining temperature control during the critical shutdown phase.
2Loss of energy
If the power supply is completely cut off when the ignition switch is turned off to eliminate dark current, then battery drain is prevented, but the blower cannot continue cooling based on thermal conditions
Solution Approach 1:
The control circuit is configured to maintain power supply for a predetermined period after ignition switch-off, automatically extending operation based on thermal conditions without requiring continuous monitoring. This preliminary automated extension ensures cooling continues when thermally necessary while automatically cutting off to eliminate dark current.
Solution Approach 2:
The blower apparatus autonomously determines when to continue operation or cut off power based on thermal conditions and predetermined timing, without requiring continuous external control signals. The system serves itself by automatically extending operation during the post-shutdown period when cooling is still needed, then self-terminating to eliminate dark current.
3Ease of operation
If the timer remains powered after the ignition switch is turned off to control the cooling operation, then the cooling control function is maintained, but a small amount of dark current flows through the timer
Solution Approach 1:
The timing control function is extracted from the main control circuit and implemented as a dedicated control circuit with predetermined timing characteristics. This extracted timing function automatically cuts off power after the predetermined period, eliminating the need for continuous powered monitoring and thereby eliminating dark current while maintaining automatic control capability.
Solution Approach 2:
The system replaces continuous electronic monitoring and control with a predetermined timing mechanism that automatically executes the power cut-off function. This substitution eliminates the need for continuous powered control circuits, removing the source of dark current while preserving the automatic cooling control function through the predetermined timing mechanism.
Data Source
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AI summary
A blower apparatus 100 in which power supply voltage Vig from a battery 70 is supplied to a power supply input terminal Tv1 through a power supply switch 71 of which on-off control is made according to a state of an ignition switch of a vehicle, comprising a motor 13 having a stator 11 with a coil 16 wound therearound and a rotor 12 disposed rotatably about a rotation shaft; a blowing fan 103 on the rotation shaft 20; a motor drive circuit 35 for electrically driving the coil 16; a microprocessor 34 for controlling the motor drive circuit 35; a motor case 14 integrally containing the motor 13, the motor drive circuit 35, and the microprocessor 34; an internal power line 32 for supplying the power supply voltage Vig applied to the power supply input terminal Tv1 to the motor drive circuit 35 and the microprocessor 34 in the motor case 14; a smoothing capacitor 33 connected to the internal power line 32; a cut off control circuit 38 for cutting off supply of the power supply voltage Vig to the internal power line 32 according to a command from the microprocessor 34, wherein the cut off control circuit 38 makes the power supply switch 71 turn off to cut off supply of the power supply voltage to the internal power line 32, which causes the microprocessor 34 and the motor drive circuit 35 to be in an inoperable state.