Denso Corporation

Takaji Murakawa

Tetsuji Kozaki

Nobuyori Nakajima

In executing an ETC cooperative downshift operation based on a driver's intent to decelerate, this system executes an engine output increasing control (e.g. a combination of a throttle opening control and a fuel injection restoring control) for increasing the engine output irrespective of driver's accelerator operation. At the timing a reduction amount in an input shaft rotational speed Nt exceeds a predetermined value K after the ETC cooperative downshift control is started, it is presumed that the hydraulic pressure of a to-be-disengaged clutch is already reduced to a hydraulic pressure level equivalent to a predetermined transmission torque capacity that causes no undesirable acceleration or shock even if the engine output increasing control is started. And, under such assumption, the engine output increasing control is started at this timing. Accordingly, the present invention can accurately set the start timing of the engine output increasing control so as to suppress any undesirable acceleration or shock caused by the engine output increasing control.

Control apparatus for an automatic transmission and related control method

A hydraulic pressure of each corresponding one of a plurality of friction elements of a gear shift mechanism of the automatic transmission is controlled to downshift the gear shift mechanism from a current gear stage to a next gear stage, at which an engine brake is operated, upon receiving a driver's demand for deceleration. An engine output of the engine is increased by increasing a throttle opening degree of the engine in at least two steps in an absence of a driver's operation on an accelerator of the vehicle at the time of the downshifting of the gear shift mechanism from the current gear stage to the next gear stage.

Control device and method for automatic transmission

An automatic transmission control system equipped with a shift lever position sensor which includes a plurality of switches which output binary signals following a shifting motion of a gear shift lever. Patterns of combinations of the switch outputs are preselected so as to represent positions to which the gear shift lever is manually shiftable. The switches are broken down into two groups each of which produces a binary code carrying information about the position of the gear shift lever to monitor a failure in operation of the shift lever position sensor. The control system also works to perform a deemed D-position hydraulic transmission control to ensure the running of the vehicle even if the shift lever position sensor is failing.

Automatic transmission control system

An automotive automatic transmission control system is provided which is designed to increase the output of an engine in response to a driver's request to downshift a transmission for setting up the engine braking and to load the amount of working fluid to an on-coming clutch quickly during the downshift. The system works to determine whether the loaded amount of working fluid is excessive or lacking using the speeds of an input shaft of the transmission and the engine to correct the amount of working fluid to be used upon a subsequent downshift request. The use of the two speeds enables the fact that the loaded fluid amount is excessive which arises from a rise in the speed of the input shaft caused by the engine output increasing control, not by completion of the loading of the working fluid to the on-coming clutch to be found accurately.

Downshift control for automotive automatic transmission

An automotive automatic transmission control apparatus is provided which works to increase the power of an engine in response to a request to down-shift the gear of an automatic transmission for developing the engine braking. The control apparatus includes a fail-safe circuit working to stop increasing the power of the engine when a defect in operation of a transmission hydraulic control circuit is detected after the hydraulic control circuit starts to control the hydraulic pressures to achieve the downshift of the automatic transmission. This eliminates or alleviates a problem, such as unwanted acceleration of the vehicle during the control of the downshift in the transmission.

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Anjo, Japan

Takaji Murakawa