Patent ID: 8656764
Filing Date: 2014-02-25
Classification: F02D,G01F

Abstract:
1. A flow-rate measuring apparatus comprising: a flow-rate sensor, which is provided in a bypass air passage for abstracting a part of intake air of a main flow, and which outputs an electrical signal depending on an air flow amount; and an output converting unit for converting an output of the flow-rate sensor to a flow-rate based on an output-and-flow-rate conversion characteristic, wherein: the output-and-flow-rate conversion characteristic for an area of a backward air-flow is set based on a relationship between an output and a flow-rate, which are obtained in an air flow in which pulsation including the backward air-flow is generated, an air-flow from an upstream side to a downstream side in the main flow is defined as a forward air-flow, while an air-flow from the downstream side to the upstream side in the main flow is defined as the backward air-flow, a flow-rate waveform, which is measured by a reference sensor having a predetermined response time and which is obtained by measuring behavior of air flow in a condition of the pulsation including the backward air-flow, is defined as a reference flow-rate waveform, a flow-rate waveform, which is obtained by applying a process for a response-delay or a response-advance to the reference flow-rate waveform so that the reference flow-rate waveform is matched to a response time of the flow-rate sensor, is defined as a response-processed reference waveform, a flow-rate waveform, which is measured by the flow-rate sensor and which is obtained by measuring the behavior of the air flow in the condition of the pulsation including the backward air-flow, is defined as a sensor-output flow-rate waveform, and the output-and-flow-rate conversion characteristic for the area of the backward air-flow is so set that the sensor-output flow-rate waveform is adapted to the response-processed reference waveform.