Interrelated power delivery controls – including engine control – Transmission control – Engine controlled by transmission
Reexamination Certificate
1999-10-25
2001-07-03
Marmur, Charles A (Department: 3681)
Interrelated power delivery controls, including engine control
Transmission control
Engine controlled by transmission
Reexamination Certificate
active
06254508
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. HEI 10-311266 filed on Oct. 30, 1998 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a speed-change control apparatus for an automatic transmission that is installed in a motor vehicle and, more specifically, to a speed-change control apparatus for controlling both engine torque and hydraulic pressure for changing speed stages and, in particular, to a speed-change control apparatus which provides a multiple speed-change operation wherein, during a certain speed-change operation, a command to establish another speed stage is issued.
2. Description of the Related Art
U.S. Pat. No. 4,688,450 discloses a speed-change control apparatus for changing engine torque during a speed-change operation. This speed-change control apparatus relates to speed-change control wherein during a certain (first) speed-change operation, a command to establish another (second) speed-change stage is issued. In this speed-change control apparatus, if a command to perform the second speed-change operation is issued prior to termination of the first speed-change operation, the engine torque control is suspended immediately as to both the first and second speed-change operations.
For example, as shown in
FIG. 11
, during an up-shift operation (e.g. from the first speed to the second speed), as the speed-change operation proceeds through engagement and disengagement of frictional engagement elements, the rotational speed N
T
of the input shaft continues to rise with a low-speed gear ratio in a torque phase, whereas the rotational speed of the input shaft falls toward a high-speed gear ratio in an inertia phase (see the line of alternating short and long dashes in FIG.
11
). In this state, if it is determined that the inertia phase has been reached based on detection of a change in rotational speed of the input shaft, a control routine is performed to reduce the engine torque T
E
by the predetermined amount (T
C
). Then, if a command to perform a down-shift operation (e.g. from the second speed to the first speed) is issued, the aforementioned engine torque control is suspended immediately. Then, a command to set the engine torque back to an intrinsic torque T
E
is issued.
In the aforementioned speed-change control apparatus, upon issuance of a command to perform the second speed-change (down-shift) operation, the hydraulic pressure that is on the engagement side during the first speed-change (up-shift) operation is reduced immediately, so that a change in rotational speed (a rise in rotational speed of the input shaft) is generated through the second speed-change (down-shift) operation. On the other hand, as described above, a command to suspend the engine torque control is also issued immediately in response to the command to perform the second speed-change (down-shift) operation. Therefore, the rotational speed of the input shaft tends to rise. In circumstances where the engine torque may change abruptly, the hydraulic pressure control needs to be performed during the second speed-change (down-shift) operation. However, the characteristic of the feedback control of the aforementioned hydraulic pressure for change in rotational speed of the input shaft is unsuitable. That is, as indicated by a dotted line in
FIG. 11
, the rotational speed N
T
of the input shaft rises abruptly and tends to overshoot.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide a speed-change control apparatus for an automatic transmission that solves the above-described problem by changing engine torque control in a state where the second speed-change operation (the other speed-change operation) has actually started.
According to the present invention, there is provided a speed-change control apparatus for an automatic transmission, comprising an input shaft, an output shaft, a plurality of frictional engagement elements, hydraulic servos, hydraulic pressure control means, engine control means, a control unit, multiple speed-change determination means, hydraulic pressure command means, speed-change start determination means and engine torque change means. The input shaft, receives power from an engine output shaft. The output shaft is coupled to the vehicle wheels. The frictional engagement elements change power transmission paths between the input shaft and the output shaft of the transmission. The hydraulic servos operate to engage and release the frictional engagement elements. The hydraulic pressure control means controls hydraulic pressures applied to the hydraulic servos and the engine control means controls an output torque of the engine. The control unit receives signals from respective sensors which monitor various vehicle running conditions and outputs signals to the hydraulic pressure control means and the engine control means. The multiple speed-change determination means determines that during one of an up-shift speed-change operation and a down-shift speed-change operation, a command to perform the other speed-change operation has been issued. The hydraulic pressure command means switches a hydraulic pressure command for performing one of the speed-change operations to a hydraulic pressure command for performing the other of the speed-change operations, and outputs the latter to the hydraulic pressure control means based on the determination of the multiple speed-change operation. The speed-change start determination means detects that one of the speed-change operations has been switched to the other by hydraulic pressure control performed by the hydraulic pressure control means responsive to the hydraulic pressure command, and determines that the other (second) speed-change operation has actually started. The engine torque change means issues a command to change torque-down control by the engine control means responsive to determination of the second start of the speed-change operation.
In the speed-change operations, the hydraulic pressure supplied to the hydraulic servo for one of the frictional engagement elements is raised, and the hydraulic pressure supplied to the hydraulic servo for the other frictional engagement element is lowered to effect either an up-shift speed-change operation or a down-shift speed-change operation. During an up-shift operation, the torque capacity of the one frictional engagement element increases. The engine control means reduces the engine torque by a predetermined amount when there occurs a change in rotational speed of the input shaft (inertia phase).
During one of the speed-change operations, if a command to perform the other (second) speed-change operation is issued, the hydraulic pressure command means suspends the one speed-change operation immediately, and lowers the hydraulic pressure for the one frictional engagement element and raises the hydraulic pressure for the other frictional engagement element in executing the second speed-change operation. Based on the command to raise the hydraulic pressure for the other frictional engagement element, the start of the other speed-change operation is determined, i.e., it is determined that the one speed-change operation has been replaced by the other and that the actual speed-change state has changed.
Based on determination of the start of the second speed-change operation, for example in the case where an up-shift operation has been replaced by a down-shift operation, the torque-down control which accompanies the up-shift operation is suspended and the torque is restored with a predetermined gradient. In the case where a down-shift operation has been replaced by an up-shift operation, the torque-down output is changed such that the torque-down control during the aforementioned up-shift operation is started. As indicated by a solid line in
FIG. 11
, for example, the torque-down control for the engine is thereby restored after the actual second speed-change operation has started. T
Kojima Kouichi
Nishida Masaaki
Saitou Masao
Tsutsui Hiroshi
Yamamoto Yoshihisa
Aisin Aw Co. Ltd.
Lorusso & Loud
Marmur Charles A
Parekh Ankur
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