摘要:
When a gearshift command for a power-on/downshift or power-off/upshift mode is issued, the magnitude of a change in the engine rotational speed due to the gearshift is calculated from the vehicle speed or the engine rotational speed when the gearshift starts to be effected and the gear ratio of a gear position to be reached by the gearshift. If the magnitude of the engine speed change is large, then a hydraulic control pressure is lowered for a certain period of time to advance the timing of operating of a hydraulic pressure release valve to quickly disengage a previous-gear-position clutch. If the magnitude of the engine speed change is small, then the control pressure is increased to delay the timing of operation of the hydraulic pressure release valve to allow the previous-gear-position clutch to be disengaged after a next-gear-position clutch starts to be engaged.
摘要:
If the accelerator pedal condition is a power-on condition and the gearshift type is an upshift, or the accelerator pedal condition is a power-off condition and the gearshift type is a downshift, then a torque for engaging the next-gear-position gearshift means is established based on the engine torque to be transmitted from the engine to the next-gear-position gearshift means, and an inertia torque required to make the rotational speed of the input member of the next-gear-position gearshift means vary as desired with respect to the gearshift. If the accelerator pedal condition is a power-on condition and the gearshift type is a downshift, or the accelerator pedal condition is a power-off condition and the gearshift is an upshift, then the ratio between the rotational speeds of the input and output members of the next-gear-position gearshift means is detected. The torque for engaging the next-gear-position gearshift means is lowered after the gearshift is started until the detected rotational speed ratio reaches a predetermined value. After the detected rotational speed ratio has reached the predetermined value, the engaging torque is set to a vaslue large enough to engage the gearshift means.
摘要:
A control for shifting from an off-going speed range to an on-coming speed range comprises an off-going range releasing stage, an on-coming range void-stroke-clearing stage, an on-coming range engaging stage and an on-coming range final stage. During the off-going range releasing stage, an off-going engaging element is released in response to a shift command signal. During the on-coming range void-stroke-clearing stage, the engagement-actuation pressure of the on-coming engaging element is set at a predetermined high-pressure for a predetermined time period after the shift command signal is generated, whereby the void stroke of the on-coming engaging element is cleared. During the on-coming range engaging stage, after the completion of the on-coming range void-stroke-clearing stage, the on-coming engaging element is engaged. During the on-coming range final stage, following the on-coming range engaging stage, the on-coming engaging element is engaged completely. In this control, based on the condition of the engaging operation of the on-coming engaging element during the on-coming range engaging stage, the predetermined time period for the on-coming range void-stroke-clearing stage is corrected for a next shift operation.
摘要:
A shift control method for executing a shift-up control from an off-going range to an on-coming range comprises an off-going-range releasing stage, an off-going-range controlling stage, and an on-coming-range invalid-stroke-clearing stage. In the off-going-range releasing stage, a pressure command signal is generated to quickly lower the engagement-actuation pressure of the off-going engaging element. In the off-going-range controlling stage, a pressure command signal is generated to control the engagement-actuation pressure of the off-going engaging element in such a way that the off-going engaging element is kept slipping within a predetermined range of input/output rotational speed ratio (=output rotational speed/input rotational speed). In the on-coming-range invalid-stroke-clearing stage, a pressure command signal is generated to set the engagement-actuation pressure of the on-coming engaging element to a predetermined high-pressure which is necessary for the on-coming engaging element to clear its invalid stroke. This shift-up control initiates the on-coming-range invalid-stroke-clearing stage in response to a shift-up command and proceeds from the off-going-range releasing stage to the off-going-range controlling stage when the input/output speed ratio of the off-going engaging element reaches a first predetermined value in the off-going-range releasing stage. Then, pressure command signals are generated sequentially first to engage the on-coming engaging element in a predetermined engaging pattern and then to completely release the off-going engaging element.
摘要:
A system for controlling gear (gear ratio) shifting in an automatic transmission mounted on a vehicle, including a shift control means for generating a shift command to upshift from one gear (gear ratio) currently established to a next gear (gear ratio) by determining a command to the solenoid valves to discharge the pressurized oil from the frictional engaging elements that establish the current gear (gear ratio) so as to slip-control the frictional engaging elements, and to charge the pressurized oil to the frictional engaging elements that establish the next gear (gear ratio) to be shifted to. The system includes a first step for determining the command such that an actual slip rate of the frictional engaging elements that establish the current gear (gear ratio) converges to a first desired slip rate, a second step for determining the command such that the actual slip rate of the frictional engaging elements that establish the current gear (gear ratio) converges to a second desired slip rate, maximum slip rate detecting means for detecting a maximum actual slip rate, slip rate difference calculating means for calculating a difference between the detected maximum actual slip rate and the second desired slip rate, command correcting means for correcting the command in response to the calculated difference, and command storing means for storing the corrected command to be used as the command in the first step in controlling a next upshift. This arrangement can avoid the clutches (and brakes) from being suffered excessive slippage, thereby improving the service life of the clutches and brakes and making the control to smooth shift to that for the next gear (gear ratio).
摘要:
An engagement-actuation control for a frictionally engaging element to establish a driving range in response to a shift command to shift from a neutral range to the driving range comprises a plurality of control stages including an invalid-stroke-clearing control. This invalid-stroke-clearing control is finished when invalid-stroke clearing is judged complete on the basis that the absolute value of the rate of rotational change of a turbine shaft is equal to or greater than a predetermined rate and that the difference between the rotational speed of an engine and the rotational speed of the turbine shaft is equal to or greater than a predetermined value.
摘要:
A shift control system for an automatic transmission comprises a shift lever 201, which is shifted among a “P” position, an “N” position and an “S” position. A first shift guide path 211 is provided to guide the shift lever from the “P” position through the “N” position to the “S” position, and a second shift guide path 212 is provided to guide the shift lever which has been positioned at the “S” position in a direction different from that of the first shift guide path. Along this second shift guide path, the shift lever is shifted to select and set a plurality of ranges necessary for driving a vehicle, including a forward drive range, a neutral range and a reverse drive range.
摘要:
A shift control for a shift-down operation is executed by carrying out the following stages in order: an off-going range releasing stage STO1 which quickly lowers the engagement actuation pressure of the off-going engaging element to an engagement-releasing pressure; an off-going range controlling stage STO2, STO3 and STO4 which sets the engagement actuation pressure of the off-going engaging element to a pressure a little higher than the engagement-releasing pressure; an on-coming range void-stroke-clearing stage STR1 which sets the engagement actuation pressure of the on-coming engaging element to a predetermined high-pressure necessary for clearing the void stroke; an on-coming range waiting stage STR2 and STR3 which sets the engagement actuation pressure of the on-coming engaging element to a stand-by pressure necessary for retaining the on-coming engaging element in stand-by condition prior to engagement; an off-going range final stage which releases the off-going engaging element completely; and an on-coming range final stage which engages the on-coming engaging element completely.
摘要:
An automatic transmission includes a plurality of power transmitting gear trains making up a combination of forward power transmitting paths that can be selected one at a time, a plurality of frictional engaging elements for selecting one of the forward power transmitting paths at a time, and a one-way clutch for establishing a lowest-speed gear position among the forward power transmitting paths. When a gear shift is to be made from a neutral gear range to a forward gear range, one of the frictional engaging elements which is mechanically coupled to the one-way clutch is preliminarily engaged. When the gear shift can be made from the neutral gear range to the forward gear range, one of the frictional engaging elements for establishing the starting gear position starts being engaged, and thereafter those frictional engaging elements which are not necessary to establish the starting gear position are released. Because the frictional engaging element is mechanically coupled to the one-way clutch is preliminarily engaged, vibrations produced upon rotation of the one-way clutch are reliably suppressed when the gear shift is made from the neutral gear range to the forward gear range.
摘要:
A shift control apparatus controls the shifting of a transmission by selecting one power transmitting path at a time from a plurality of paths respectively having different speed reduction ratios. At least one power transmitting path is provided with a one-way clutch and an engine-brake clutch is included in the plurality of paths. The one-way clutch can be locked by the engine-brake clutch. An engine-brake clutch control valve is provided for controlling the engine-brake clutch. Two solenoid valves are provided for controlling the engine brake clutch control valve. When one of the two solenoid valves fails and is inactivated, the other solenoid valve is used to cause the engine-brake clutch control valve to engage the engine-brake clutch.