Alternating Air Pump Control for Engine Secondary Air Supply
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Solution Overview
Problem
The existing secondary air supply systems for internal combustion engines experience voltage drops due to inrush currents from air pumps and produce operation sounds that cause a feeling of strangeness due to timing differences in the operation of air switching valves.
Innovation Solution
A secondary air supply system with a control unit that adjusts the start timings and opening timings of air pumps and air switching valves to minimize voltage drops and synchronize the operation sounds, ensuring the time difference between air switching valve openings is shorter than the time difference between air pump start timings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air pumps are operated simultaneously to supply secondary air to both exhaust pipes, then exhaust gas purification performance is improved, but battery voltage drops excessively due to large inrush currents
Solution Approach 1:
The patent applies periodic action by operating air pumps in an alternating sequence rather than simultaneously. The control unit switches between operating the first air pump and the second air pump in periods, ensuring that only one air pump operates at any given time. This periodic operation pattern reduces the instantaneous inrush current demand on the battery while maintaining adequate secondary air supply to both exhaust pipes for catalyst activation and exhaust gas purification.
2Loss of energy
If a time difference is provided between air pump start timings to suppress battery voltage drop, then battery voltage stability is improved, but air switching valves open at different timings causing tone sound that creates a feeling of strangeness
Solution Approach 1:
The patent merges the operation timing of both air switching valves by controlling them to open simultaneously, even though the air pumps operate at different times. The control unit provides a predetermined time period from when each air pump starts operation to when its corresponding air switching valve opens, and adjusts this period so that both valves open at the same time. This merging of valve opening timings causes the operation sounds to coincide and be heard as a single sound rather than successive tones, eliminating the strange feeling while maintaining battery voltage stability through alternating pump operation.
Data Source
AI summary
In an internal combustion engine that includes a first secondary air supply unit having a first air pump and a first air switching valve and a second secondary air supply unit having a second air pump and a second air switching valve, a time difference is provided between the operation start timing of the first air pump and the operation start timing of the second air pump, and the open timing of the first air switching valve and the open timing of the second air switching valve are set so as to be simultaneous with each other.