Interrelated power delivery controls – including engine control – Transmission control – Transmission controlled by engine
Reexamination Certificate
2001-09-18
2003-09-09
Wright, Dirk (Department: 3681)
Interrelated power delivery controls, including engine control
Transmission control
Transmission controlled by engine
C477S155000
Reexamination Certificate
active
06616576
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to gear shift controlling system and method for an automatic transmission. Especially, in the automatic transmission, a plurality of frictional elements are provided and a gear shift is carried out in such a manner that at least a first frictional element is clutched (or engaged) or de-clutched (or released) by supplying or draining (connecting or disconnecting) a working oil for an actuator for the first frictional element with a pressure controller or the working oil of another actuator for a second frictional element is transferred from a release state to a clutched state due to a rise in pressure the working oil of the actuator for at least the first frictional element is supplied and drained (connected and disconnected) to and from the first frictional element to render the first frictional element from a release state to a clutched state due to a rise in pressure of the working oil of the actuator for a pressure controller and a pressure reduction of the working oil of the actuator for a second frictional element by a second controller causes the state of the second frictional element to be transferred from the clutch state to the release state.
b) Description of the Related Art
In the automatic transmission, a plurality of frictional elements such as clutches and brakes are selectively activated to be clutched state under a liquid pressure to determine a power transmission path (gear range) in a gear transmission system. The frictional element to be activated is switched so that a gear shift to another gear range is carried out.
It is well known that with the gear shift control for the automatic transmission, the working oil of the actuator for at least first frictional element is supplied or drained to clutch or de-clutch the first frictional element, or the working oil of the actuator for at least the frictional element is supplied or drained to shift the state of the first frictional element from the released state or clutched state due to the rise in pressure with the pressure controller and the pressure reduction of the working oil of the actuator for the second frictional element causes the second frictional element to be in the released state from the clutched state, and the gear shift from a certain gear range to another gear range is advanced.
It is noted that although the shift control system and method according to the present invention are not limited to an interchange (or clutch-to-clutch) shift of 1 versus 1 (one release element and one clutching element), one example of the interchange shift will be described below to help clarification of the background of the invention.
In this example, in the automatic transmission, the gear shift is carried out by a, s-called, interchange shift (clutch-to-clutch shift) of the frictional element in such a way that while releasing a certain frictional element due to a reduction in a working liquid pressure (pressure reduction in the working oil of the actuator by means of a pressure controller), another frictional element is clutched in response to arise in the working liquid pressure by the pressure controller.
It is noted that the frictional element to be switched from the clutch state to the release state is called a release side frictional element and its working liquid pressure is called a release side working liquid pressure. In addition, the frictional element to be switched from the release state to the clutched state is, called, a release side frictional element, and its working liquid pressure is, called, a clutch side working liquid pressure.
Hence, it is possible to complete the shift with a release-and-clutch control for these frictional elements, while the release side frictional element is released due to the rise in the clutch side working liquid pressure and the clutch side frictional element.
A Japanese Patent Application First Publication No. Heisei 2000-065198 (JP2000065198) published on Mar. 3, 2000 exemplifies a previously proposed a drive down controller. In the drive down controller, a transmission controller prevents a racing after the end of an inertia phase by setting a sum of a capacity of both clutch side and release side frictional elements during the end of shift to a value equal to or larger than an input torque ×1.0.
It is noted that the term of “racing” or “races” points to a state in which, in a case of a gear ratio in the down shift mode, the gear ratio exceeds a normal gear ratio upon the end of the gear shift and is shifted to a lower gear ratio.
SUMMARY OF THE INVENTION
As described above, the racing can be effectively be prevented according to the drive down controller disclosed in the above-described Japanese Patent Application First Publication. However, more further improvements are needed in view of the following respects.
(A) Since, according to the above-described previously proposed drive down gear shift controller, a time at which the inertia phase is ended and predicted and the gradient is determined. If the inertia phase is ended at a prediction time, a target hydraulic is reached when the inertial phase is ended.
Hence, if the end time of the inertia phase is deviated from the prediction time with actual input torque and/or release transmission torque differed from its estimated value, the hydraulic during the end of inertia phase does not become the aimed (target) hydraulic. Consequently, a racing prevention function that the drive down controller has cannot sufficiently be exhibited.
(B) Next, referring to
FIGS. 16A and 16B
,
FIG. 16A
shows a case where an actual input torque is larger than that the controller recognizes or a release transmission is smaller than that the controller recognizes (too early (or too fast) in the advance of gear shift) and
FIG. 16B
shows a case wherein the actual input torque is smaller than that the controller recognizes (too slow (too late) in the advance the gear shift).
In
FIGS. 16A and 16B
, concerning with the gear ratio, a variation in the actual gear ratio is denoted by a solid line and a variation in a predicted gear ratio is denoted by a broken line. In addition, A denotes the aimed, viz., the target hydraulic at the time of inertia phase end (at the release command pressure side), A′ denotes the aimed, viz., the target hydraulic at the time of the end of inertia phase (clutch command pressure side), B denotes the aimed hydraulic, viz., the target hydraulic at the release command pressure side when the inertia phase is actually ended and B′ denotes the hydraulic at a side of the clutch command pressure when the inertia phase is actually ended.
In either of the cases shown in
FIGS. 16A and 16B
, the actual input torque and release transmission torque are different from their estimated values and the end time of the inertia phase is deviated from the predicted time. At this time, the hydraulic at the time of end of inertia phase does not become the aimed one. In the case of
FIG. 16A
(too early in the advance of the gear shift), each hydraulic B and B′ at which the actual inertia phase is lowered than the aimed hydraulic A and A′ at the time of ending the inertia phase.
In the case of
FIG. 16B
, (it is slow in advancing the gear shift) the hydraulic B when the inertia phase is actually ended is in excess of the aimed hydraulic A when the inertia phase is ended. In this way, the hydraulic is not easy to be settled as desired.
Hence, when the advance in the gear shift is too early (FIG.
16
A), the release pressure is ended with small release pressure. At this time, there is a great possibility in the occurrence in racing. When the gear shift is slow in advancing the gear shift (FIG.
16
B), the release pressure is furthermore raised so that it further becomes difficult to advance the gear shift.
(C) Hence, it is desired to avoid the above-described state by an introduction of new ideas and new techniques and to secure an appropriate gear shift control for the automatic transmission.
It is, hence, an object of th
Jatco LTD
Wright Dirk
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