Denso Corporation

Toyota Jidosha Kabushiki Kaisha

Toyota Technical Development Corporation

Shinya Sakaguchi

Akira Takagi

Naohiro Yoshida

Nobuo Fujita

Tadaichi Matsumoto

Hiroaki Mori

Kenji Kurita

Kimihide Horio

Kazushi Nakatani

Toshiyuki Kawai

Kunio Okamoto

Tomonori Imamura

Hideshi Izuhara

Hideki Kashiwagi

Tetsuroh Kikuchi

The fuel cell system is provided which detects a freeze among specific components and portions thereof by evaluating various conditions upon starting operation of the fuel cell system. If a freeze is detected through those evaluations, the start of the system is prohibited in order to prevent some deterioration in the fuel cell system.

Fuel cell system and method of controlling the same fuel cell system

A fuel cell system, control method and current measuring device for a power unit are disclosed. The fuel cell system includes a fuel cell having local areas, a current measuring device associated with at least one of the local areas to measure localized current related to a specified operating characteristic, and a control section for diagnosing an operating condition of the fuel cell in response to localized current to enable optimum control of the fuel cell depending upon a specified operating characteristic determined by localized current. The control method controls the operating condition of the fuel cell in response to localized current indicative of the specified operating characteristic of the fuel cell. The current measuring device includes an electrical conductor formed with a recessed portion, a localized current conductor received in the recessed portion, and a current sensor for detecting current flowing across the localized current conductor.

Fuel cell system, related method and current measuring device for fuel cell system

A hydraulic pressure control system for an automatic transmission is capable of reducing the size and simplifying the structure of a lockup controlling hydraulic circuit. An oil pressure output from a solenoid valve acts on an oil pressure chamber. The internal pressure of another oil pressure chamber becomes high only in a forward low-speed range and becomes low in all of the other gear shift ranges. The internal pressure of another oil pressure chamber becomes high only in forward ranges and becomes low in neutral and reverse ranges. The valve member moves in accordance with oil pressures applied to the oil pressure chambers to change over oil paths connected to a clutch control oil chamber and a torque converter oil chamber, whereby a lockup clutch assumes one of engaged, slip, and released states. Since an oil pressure signal according to a gear shift range and a vehicular running range is fed to the changeover valve and on the basis of this signal the changeover valve determines whether the engagement of the lockup clutch is to be permitted or inhibited, the circuit of a lockup control unit can be reduced in size and simplified.

Hydraulic pressure control system

To provide a hydraulic controller for automatic transmission use which commonalizes a lockup control valve and a friction engagement element control valve, thereby simplifying a hydraulic circuit, reducing the number of parts, and achieving low cost, a lockup solenoid to control engagement or release of a lockup clutch, a first friction engagement element to engage an friction engagement element only in a portion or entirety of a shifting stage to prohibit lockup, and a manual shift lever to determine whether a vehicle exists in a lockup prohibition condition are provided. A switching valve selectively switches the lockup solenoid to either communicate with the lockup clutch or communicate with the foregoing first friction engagement element. The manual shift valve is disposed in a path extending from the switching valve to the first friction engagement element.

Hydraulic controller for automatic transmission use

Hydraulic pressure applied to an LR/B is controlled by a first solenoid valve when a forward-movement range is selected, and is controlled by a second solenoid valve when a backward-movement range is selected. In addition, in the forward-movement range, the second solenoid valve controls hydraulic pressure applied to an OD/C which couples at a different gear position from the LR/B. When both solenoid valves fall into non-excitation states due to the breaking of an electric signal line, the failure of an AT ECU or the like, the output hydraulic pressures of the solenoid valves is held high and low, respectively. Therefore, even in this case, double coupling of the LR/B and the OD/C can be prevented in the forward-movement range as well as a predetermined gear position can be established in each of the forward-movement range and the backward-movement range.

Hydraulic pressure control apparatus for an automatic transmission

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Bisai, Japan

Shinya Sakaguchi