Control apparatus for an automatic transmission
First Claim
1. A control apparatus of an automatic transmission of a vehicle, comprising:
- a fluid transmission gear for transmitting the rotation of an engine to transmission apparatuses;
a clutch which is engaged when a forward running range is selected to couple said fluid transmission gear to said transmission apparatuses;
a one-way clutch which is locked by engagement of said clutch to achieve a forward 1st gear ratio of said transmission apparatuses;
a brake for locking said one-way clutch by the engagement in order to prevent an output shaft of said transmission apparatuses from rotating in a reverse direction;
a first hydraulic servo for engaging said clutch by a hydraulic pressure applied thereto;
a second hydraulic servo for engaging said brake by a hydraulic pressure applied thereto;
a stop-state detecting means for determining that the vehicle is in a halted state when a speed of the vehicle is virtually zero, an acceleration pedal is released and a foot-brake pedal is stepped on;
a gradient detecting means for detecting the gradient of a road; and
a control means for controlling hydraulic pressures applied to said first and second hydraulic servos in accordance with signals generated by said stop-state detecting means and said gradient detecting means,wherein said control means comprises;
a judgment means for determining in accordance with said signal output by said gradient detecting means whether an uphill road is steep enough to cause said brake to slip, with said brake engaged;
a hydraulic pressure reducing means for reducing a hydraulic pressure applied to said first hydraulic servo in order to place said clutch in an all but released state;
a hydraulic pressure applying means for applying a hydraulic pressure to said second hydraulic servo in order to place said brake in an engaged state; and
an execution means for permitting said hydraulic pressure reducing means to reduce a hydraulic pressure applied to said first hydraulic servo and said hydraulic pressure applying means to apply a hydraulic pressure to said second hydraulic servo only if a stop state is detected by said stop-state detecting means and said judging means determines that an uphill road is not steep enough to cause said brake to slip.
1 Assignment
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Accused Products
Abstract
The invention provides a control apparatus for an automatic transmission for carrying out neutral control and hill-hold control in a range that causes no slip of a hill-hold brake. The control apparatus has a judgment unit for determining, in accordance with a signal output by a gradient detector whether an uphill road is steep enough to cause a hill-hold brake to slip with the hill-hold brake engaged, a hydraulic pressure reducing device for reducing the hydraulic pressure applied to a hydraulic servo of a clutch in order to place the clutch in an all but released state, a hydraulic pressure applying device for applying a hydraulic pressure to a hydraulic servo of a brake in order to engage the brake, and an execution unit for permitting the hydraulic pressure reducing device to reduce the hydraulic pressure applied to the hydraulic servo and the hydraulic pressure applying device to apply a hydraulic pressure to the hydraulic servo only if a stop, or halted, state is detected by a stop-state detector and an uphill road is determined by the judgement unit not to be steep enough to cause the hill-hold brake to slip.
34 Citations
7 Claims
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1. A control apparatus of an automatic transmission of a vehicle, comprising:
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a fluid transmission gear for transmitting the rotation of an engine to transmission apparatuses; a clutch which is engaged when a forward running range is selected to couple said fluid transmission gear to said transmission apparatuses; a one-way clutch which is locked by engagement of said clutch to achieve a forward 1st gear ratio of said transmission apparatuses; a brake for locking said one-way clutch by the engagement in order to prevent an output shaft of said transmission apparatuses from rotating in a reverse direction; a first hydraulic servo for engaging said clutch by a hydraulic pressure applied thereto; a second hydraulic servo for engaging said brake by a hydraulic pressure applied thereto; a stop-state detecting means for determining that the vehicle is in a halted state when a speed of the vehicle is virtually zero, an acceleration pedal is released and a foot-brake pedal is stepped on; a gradient detecting means for detecting the gradient of a road; and a control means for controlling hydraulic pressures applied to said first and second hydraulic servos in accordance with signals generated by said stop-state detecting means and said gradient detecting means, wherein said control means comprises; a judgment means for determining in accordance with said signal output by said gradient detecting means whether an uphill road is steep enough to cause said brake to slip, with said brake engaged; a hydraulic pressure reducing means for reducing a hydraulic pressure applied to said first hydraulic servo in order to place said clutch in an all but released state; a hydraulic pressure applying means for applying a hydraulic pressure to said second hydraulic servo in order to place said brake in an engaged state; and an execution means for permitting said hydraulic pressure reducing means to reduce a hydraulic pressure applied to said first hydraulic servo and said hydraulic pressure applying means to apply a hydraulic pressure to said second hydraulic servo only if a stop state is detected by said stop-state detecting means and said judging means determines that an uphill road is not steep enough to cause said brake to slip. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification