FAIL DETECTING APPARATUS FOR AUTOMATIC TRANSMISSION
First Claim
1. A fail detecting apparatus provided in a vehicular automatic transmission which realizes a plurality of gear positions by engagement and disengagement of friction elements in combination, for determining a state of an oil pressure switch which detects operating pressure of each friction element, comprising:
- oil pressure switch ON detecting means for detecting whether any of the oil pressure switches is ON; and
fail determining means for determining a state of the oil pressure switch based on a result of detection by said oil pressure switch ON detecting means, wherein at a time of turning-on of an ignition switch before an engine is started, said fail determining means determines that the oil pressure switch has failed when the oil pressure switch is ON.
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Accused Products
Abstract
There is provided a fail detecting apparatus for an automatic transmission which is capable of quickly detecting a failure of an oil pressure switch with accuracy. In addition to an oil pressure switch state determining process carried out while a vehicle is running, the state of an oil pressure switch is detected at the time of turning-on of an ignition switch before an engine is started, and if the oil pressure switch has continued to be ON until a timer value becomes equal to or greater than a predetermined value, it is determined that the oil pressure switch has failed. Since the state of the oil pressure switch is determined before the engine is started, i.e. in the state in which no oil pressure has been generated, whether the oil pressure switch is normal or has failed can be determined with high accuracy irrespective of which range is currently selected in the automatic transmission. Also, while the vehicle is running, the state of the oil pressure switch is detected when the range is switched to the P, R, or N range, and therefore it is possible to correctly determine whether the oil pressure switch for the friction element which is engaged only in the D range is normal or has failed.
19 Citations
9 Claims
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1. A fail detecting apparatus provided in a vehicular automatic transmission which realizes a plurality of gear positions by engagement and disengagement of friction elements in combination, for determining a state of an oil pressure switch which detects operating pressure of each friction element, comprising:
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oil pressure switch ON detecting means for detecting whether any of the oil pressure switches is ON; and
fail determining means for determining a state of the oil pressure switch based on a result of detection by said oil pressure switch ON detecting means, wherein at a time of turning-on of an ignition switch before an engine is started, said fail determining means determines that the oil pressure switch has failed when the oil pressure switch is ON. - View Dependent Claims (2)
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3. A fail detecting apparatus provided in a vehicular automatic transmission which realizes a plurality of gear positions by engagement and disengagement of friction elements in combination, for determining a state of an oil pressure switch which detects operating pressure of each friction element, comprising:
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oil pressure switch ON detecting means for detecting whether any of the oil pressure switches is ON;
first fail determining means for determining that the oil pressure switch has failed when said oil pressure switch detecting means detects an ON state of the oil pressure switch at a time of turning-on of an ignition switch before an engine is started; and
second fail determining means for determining that the oil pressure switch has failed when, in a range in which original pressure of operating pressure on a friction element engaged in a forward range is interrupted, said oil pressure switch detecting means detects an ON state of the oil pressure switch for the friction element engaged in the forward range after the engine is started. - View Dependent Claims (4, 5, 6, 7, 8, 9)
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Specification