Method and apparatus for speed change control of an automotive automatic transmission
First Claim
1. In an automotive automatic transmission including a first frictional engaging element for establishing a first gear stage, a second frictional engaging element for establishing a second gear stage, a first electromagnetic valve for controlling an operating oil pressure supplied to the first frictional engaging element, and a second electromagnetic valve for controlling an operating oil pressure supplied to the second frictional engaging element, a speed change control apparatus for controlling the first and second electromagnetic valves such that the first frictional engaging element, which has been engaged, is released, and the second frictional engaging element, which has been released, is engaged, to carry out a shift from the first gear stage to the second gear stage, said speed change control apparatus comprising:
- synchronized point detecting means for detecting a time point, as a synchronized point, at which the rotational speed of an input shaft of the automatic transmission reaches a rotational speed which is regarded as corresponding to the second gear stage;
first pressure increasing means for increasing the oil pressure supplied to the second frictional engaging element to a predetermined pressure, less than a pressure necessary for engagement of the second frictional engaging element, when the synchronized point is detected; and
second pressure increasing means for further increasing the oil pressure supplied to the second frictional engaging element beyond the predetermined pressure to thereby provide a two-stage supply of oil pressure to the second frictional engaging element.
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Accused Products
Abstract
During downshift operation of an automotive automatic transmission in which a lower-speed clutch for establishing a lower-speed gear is engaged while a higher-speed clutch, which has established a higher-speed gear, is disengaged, to increase the turbine rotational speed Nt toward a synchronous rotation speed Ntj associated with the lower-speed gear, speed change control is carried out according to the same control method regardless of whether the engine is in a power-on or power-off state. A target change rate (Nir)'"'"' of turbine rotational speed associated with the higher-speed clutch and a target change rate (Nia)'"'"' of turbine rotational speed associated with the lower-speed clutch are set, and a change rate (Nt)'"'"' of the turbine rotational speed is detected. The transmission torque through the higher-speed clutch is controlled in a feedback manner such that the detected change rate (Nt)'"'"' coincides with the change rate (Nir)'"'"'. Further, the transmission torque through the lower-speed clutch is feedback-controlled such that the change rate (Nt)'"'"' coincides with the change rate (Nia)'"'"', thereby carrying out downshift.
25 Citations
16 Claims
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1. In an automotive automatic transmission including a first frictional engaging element for establishing a first gear stage, a second frictional engaging element for establishing a second gear stage, a first electromagnetic valve for controlling an operating oil pressure supplied to the first frictional engaging element, and a second electromagnetic valve for controlling an operating oil pressure supplied to the second frictional engaging element, a speed change control apparatus for controlling the first and second electromagnetic valves such that the first frictional engaging element, which has been engaged, is released, and the second frictional engaging element, which has been released, is engaged, to carry out a shift from the first gear stage to the second gear stage, said speed change control apparatus comprising:
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synchronized point detecting means for detecting a time point, as a synchronized point, at which the rotational speed of an input shaft of the automatic transmission reaches a rotational speed which is regarded as corresponding to the second gear stage; first pressure increasing means for increasing the oil pressure supplied to the second frictional engaging element to a predetermined pressure, less than a pressure necessary for engagement of the second frictional engaging element, when the synchronized point is detected; and second pressure increasing means for further increasing the oil pressure supplied to the second frictional engaging element beyond the predetermined pressure to thereby provide a two-stage supply of oil pressure to the second frictional engaging element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A speed change control method for an automotive automatic transmission in which a first frictional engaging element, which has been engaged, is released, and a second frictional engaging element, which has been released, is engaged, to carry out a shift from a first gear stage to a second gear stage, said speed change control method comprising the steps of:
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(a) detecting a time point, as a synchronized point, at which the rotational speed of an input shaft of the automatic transmission reaches a rotational speed which is regarded as corresponding to the second gear stage; (b) increasing the oil pressure supplied to the second frictional engaging element to a predetermined pressure, less than a pressure necessary for engagement of the second frictional engaging element, when the synchronized point is detected in step (a); and (c) further increasing the oil pressure supplied to the second frictional engaging element beyond the predetermined pressure to thereby provide a two-stage supply of oil pressure to the second frictional engaging element. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification