Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
2001-10-26
2003-12-09
Parekh, Ankur (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
C074S339000
Reexamination Certificate
active
06658950
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a shift control device for a transmission mounted on a vehicle and, particularly, to a shift control device for a transmission equipped with a synchronizing device.
DESCRIPTION OF THE PRIOR ART
There has been put into practical use a transmission which is equipped with a select actuator for actuating a speed-changing mechanism for changing the speed of the transmission in the selecting direction and a shift actuator for actuating the speed-changing mechanism in the shifting direction, the select actuator and the shift actuator being controlled in response to a speed-change instruction from a target gear position instruction means that instructs a target gear position of the transmission.
As the select actuator and the shift actuator, there have generally been used fluid pressure cylinders using a fluid pressure such as pneumatic pressure or hydraulic pressure as a source of operation. In recent years, further, a select actuator and a shift actuator constituted by electric motors have been proposed for use in a transmission mounted on a vehicle which is provided with neither a source of the compressed air nor a source of the hydraulic pressure.
In shifting the transmission equipped with a synchronizing device, the largest operation force is required for the synchronizing operation in the gear-engaging operation, and the next largest force is required for engaging the chamfer of dog teeth with the chamfer of the spline of the clutch sleeve. In the gear-disengaging operation, further, the operation force is required from the start of the gear-disengaging operation until the dog teeth are disengaged from the spline of the clutch sleeve. Therefore, the shift actuator is designed to be operated with a driving force that is set in advance correspondingly to the shift stroke position.
During the gear-engaging operation, the required shift operation force in the synchronizing range varies depending upon the difference in the synchronizing rotational speed, which is a difference between the rotational speed of the output shaft at the start of synchronization, i.e., the rotational speed of the synchronizing side (clutch sleeve), and the rotational speed of the to-be-synchronized side (speed change gear that is to be engaged). Namely, the shift operation force may be decreased with a decrease in the difference in the synchronizing rotational speed, and may be increased with an increase in the difference in the synchronizing rotational speed. In a transmission in which the driving force of the shift actuator is controlled correspondingly to the shift stroke position, however, the driving force of the shift actuator in the synchronizing range has been set to a predetermined value. Therefore, the synchronizing time increases with an increase in the difference in the synchronizing rotational speed and decreases with a decrease in the difference in the synchronizing rotational speed. In a transmission in which the driving force of the shift actuator is controlled correspondingly to the shift stroke position as described above, the speed changing time required from when the driver has instructed to change the speed until the speed changing operation is finished, varies depending upon the difference in the synchronizing rotational speed. Hence, this is not desirable from the standpoint of feeling of the driver in changing the speed.
During the synchronizing operation, further, the stirring resistance that is produced at the time the counter gears in mesh with the speed change gears stir the lubricating oil acts in opposite directions depending upon whether the shifting is a shift-up or a the shift-down. That is, the stirring resistance advantageously acts on the synchronizing operation at the time of shift-up but disadvantageously acts on the synchronizing operation at the time of shift-down. It is therefore desired that the shift operation force in the synchronizing range at the time of shift-down be set to be larger than that at the time of shift-up even when the difference in the synchronizing rotational speed is the same.
Besides, even when the difference in the synchronizing rotational speed is the same, the synchronizing action needs an increased force with an increase in the gear ratio of the speed change gear. It is therefore desired that the shift operation force be set for each of the gear positions.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a shift control device for a transmission, which is capable of always making nearly uniform the speed changing time required from when the change of speed is instructed until the speed changing operation is finished.
In order to accomplish the above-mentioned object, the present invention provides a shift control device for a transmission, comprising a transmission equipped with a synchronizing device, a speed change operation mechanism for changing the speed of said transmission, a select actuator for actuating said speed change operation mechanism in the selecting direction, and a shift actuator for actuating said speed change operation mechanism in the shifting direction, said shift control device for a transmission further comprising:
a target gear position instruction means for instructing a target gear position of said transmission;
a shift stroke sensor for detecting a shift stroke position of said speed change operation mechanism;
an input shaft rotational speed sensor for detecting the rotational speed of the input shaft of said transmission;
an output shaft rotational speed sensor for detecting the rotational speed of the output shaft of said transmission; and
a controller for controlling said select actuator and said shift actuator based on the signals from said target gear position instruction means, said shift stroke sensor, said input shaft rotational speed sensor and said output shaft rotational speed sensor; wherein,
said controller determines the driving force of said shift actuator that corresponds to the shift stroke position based on the signals from said target gear position instruction means, said shift stroke sensor, said input shaft rotational speed sensor and said output shaft rotational speed sensor, determines the difference in the synchronizing rotational speed based on the input shaft rotational speed, the gear ratio of the target gear position and the output shaft rotational speed, and determines the driving force of said shift actuator in the synchronizing range based on said determined difference in the synchronizing rotational speed.
It is desired that the driving force of the shift actuator in said synchronizing range be obtained based on the determined difference in the synchronizing rotational speed and the gear ratio of the target gear position. The shift actuator is an electric motor, and the controller determines the driving electric power of the shift actuator in the synchronizing range.
The present invention further provides a shift control device for a transmission, comprising a transmission equipped with a synchronizing device, a speed change operation mechanism for changing the speed of said transmission, a select actuator for actuating said speed change operation mechanism in the selecting direction, and a shift actuator for actuating said speed change operation mechanism in the shifting direction, said shift control device for a transmission further comprising:
a target gear position instruction means for instructing a target gear position of said transmission;
a shift stroke sensor for detecting a shift stroke position of said speed change operation mechanism;
an input shaft rotational speed sensor for detecting the rotational speed of the input shaft of said transmission;
an output shaft rotational speed sensor for detecting the rotational speed of the output shaft of said transmission; and
a controller for controlling said select actuator and said shift actuator based on the signals from said target gear position instruction means, said shift stroke sensor, said input shaft rotational speed sensor and said output
Isuzu Motors Limited
Parekh Ankur
LandOfFree
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