Hitachi, Ltd.

Hitachi Automotive Engineering Co., Ltd.

Tetsuo Matsukura

Nobukatsu Arai

Shinya Igarashi

Toshifumi Usui

Yoshihito Sekine

Masahiro Matsumoto

Keiji Hanzawa

Atsushi Miyazaki

Hiroatsu Tokuda

Chihiro Kobayashi

Masayoshi Suzuki

Mitsukuni Tsutsui

Tadao Osawa

Haruhiko Maeda

Youichi Furuhashi

Hirokazu Fujita

An apparatus for diagnosing the characteristic of an acceleration sensor and a method for diagnosis thereof are disclosed. The acceleration sensor includes a movable electrode (or mass part) displaced in accordance with an acceleration and a fixed electrode disposed opposite to the movable electrode. In a diagnosis mode, a signal for diagnosis is applied to the fixed electrode so that an electrostatic force as a force corresponding to a predetermined acceleration is generated between the fixed electrode and the movable electrode. In the case where the acceleration sensor is sound, the movable electrode or mass part is normally displaced. A failure of the acceleration sensor, the deterioration thereof in performance, a change in characteristic thereof caused from the lapse of time, or the like is self-diagnosed by detecting a change in capacitance between the movable electrode and the fixed electrode upon generation of the diagnosis signal. The force corresponding to the predetermined acceleration may be an electromagnetic force or a mechanical oscillation based on a piezoelectric element.

System and method for diagnosing characteristics of acceleration sensor

An air flow meter comprises a main passage for an axial main air flow; an axial subpassage for air flow, disposed in the main passage and formed so that part of the air in the main passage is taken in at an upstream side thereof and flows in the same direction as the axial main air flow; a radial subpassage for air flow, intersecting the axial subpassage at a downstream side of the axial subpassage so that air from the axial subpassage flows into the radial subpassage and is divided into two radial air flows running in different radial directions; the air having passed through the radial subpassage joining the axial main air flow. An air flow sensing means is disposed in the radial subpassage for sensing a flow rate of air therein, and a projection is disposed in the radial subpassage around the intersection of the axial and radial subpassages, for suppressing turbulence of air flow around the intersection.

Air flow meter

A hot-wire air flow meter for detecting air flow intake has a main passage (21) and a generally parallel sub-passage (31) for bypassing said main passage, and located in the sub-passage is a hot-wire element (2a) for detecting air flow intake. A dished member (34) is located upstream from an inlet (31a) of the sub-passage, the dished member having a base portion adjacent the sub-passage inlet and an upstream projecting edge (30a) extending from said base portion. The upstream extending edge (30a) at least partially surrounds the inlet (31a) and is located between the sub-passage inlet and the main passage, the effect of the dished member tending to stabilize air flow entering the sub-passage so that the air flow is less affected by bends in pipework upstream from the air flow meter.

Hot-wire air flow meter and internal combustion engine provided with same

The present invention whose object is to provide a hot wire type of flow meter capable of accurately detecting a flow rate under various conditions required for satisfying a desire for low fuel consumption of an engine system and space saving in an engine room, the present invention being characterized in a hot wire type of air flow meter including a main flow passage forming an air intake flow passage of an internal combustion engine, a hot wire element measuring intake air, and a bypass having the hot wire element therein and disposed in the main flow passage, the hot wire type of air flow meter comprising: a flow passage forming the bypass, and formed in the axial direction of the main flow passage; and a flow passage forming the bypass and formed in the radial direction of the main flow passage, the flow passage having a structure designed in such a manner that the upper stream portion of an outlet portion thereof projects over the lower stream portion of the same.

Hot wire type of air flow meter and internal combustion engine using the

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Katsuta, Japan

Tetsuo Matsukura