Intake Air Flowmeter Backflow Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional intake air amount measuring devices inaccurately measure intake air due to temporary backflow, as they fail to consider backflow in their compensation for bypass delay.
Innovation Solution
The device employs a bypass-type air flowmeter with a processor that calculates intake air amount by compensating for bypass delay using different loss coefficients for forward and backflow states, ensuring accurate measurement by accounting for asymmetrical passage shapes and varying flow velocities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the conventional intake air amount measuring device compensates for bypass delay without considering backflow, then the device can maintain simple compensation logic, but the measurement accuracy deteriorates when backflow occurs
Solution Approach 1:
The patent applies local quality by using different loss coefficients specifically for backflow conditions versus normal flow conditions. The processor identifies backflow states and applies distinct compensation parameters (different loss coefficients) only when backflow is detected, rather than using a uniform compensation approach. This localized differentiation resolves the contradiction by improving measurement accuracy during backflow without requiring complete restructuring of the compensation system.
Solution Approach 2:
The patent implements parameter changes by dynamically switching loss coefficients based on flow direction. When backflow is detected, the system changes the loss coefficient parameter from the normal flow value to a specifically calibrated backflow loss coefficient. This parameter adaptation allows the compensation logic to account for backflow effects while maintaining a relatively simple overall structure, thus improving accuracy without excessive complexity.
2Adaptability or versatility
If the air flowmeter uses asymmetrical passage shapes to accommodate backflow, then the device can handle both forward and backflow states, but the loss coefficients vary between flow directions causing measurement inconsistency
Solution Approach 1:
The patent resolves this contradiction by applying local quality through direction-specific loss coefficients. The asymmetrical passage design provides adaptability for bidirectional flow, while the processor compensates for the resulting measurement inconsistency by selecting appropriate loss coefficients based on flow direction. This localized parameter adjustment ensures consistent measurement accuracy across both forward and backflow states despite the asymmetrical geometry.
Solution Approach 2:
The patent utilizes asymmetry in the passage design to enable backflow capability, and then compensates for the measurement inconsistency through asymmetric loss coefficient selection. The main passage and bypass passage have asymmetrical shapes that allow backflow, and the processor applies different loss coefficients for forward and backflow states to maintain measurement precision. This approach embraces the asymmetry rather than trying to eliminate it.
Data Source
AI summary
An intake air amount measuring device includes a by-pass-type air flowmeter and a processor that calculates an intake air amount of an engine based on the measurement result of the air flowmeter. When calculating the intake air amount, the processor performs lag or lead compensation for a response delay of a change in an intake flow rate in the bypass passage in relation to a change in an intake flow rate in the main passage based on loss coefficients of the main passage and the bypass passage. The processor causes values of the loss coefficients of the main passage and the bypass passage, which are used in the compensation, to be different between a forward flow state, in which the intake air flows through the main passage in a forward direction, and a backflow state, in which the intake air flows through the main passage in a reverse direction.