Interrelated power delivery controls – including engine control – Clutch control – Electric clutch
Reexamination Certificate
2001-01-22
2002-11-05
Schwartz, Christopher P. (Department: 3613)
Interrelated power delivery controls, including engine control
Clutch control
Electric clutch
C477S087000, C477S175000, C477S086000
Reexamination Certificate
active
06475114
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a gear-mesh type automatic transmission system capable of controlling clutch on/off operation, i.e., operation for changing over the clutch between a meshing state (on-state) and a released state (off-state). More particularly, the present invention is concerned with an improvement of the gear-mesh type automatic transmission system such that shock which may take place upon coupling of the clutch in succession to changeover of speed stage in the gear-mesh type automatic transmission system can be suppressed or mitigated regardless of time-dependent deterioration (i.e., deterioration as a function of time lapse) of the clutch.
2. Description of Related Art
Heretofore, there have been proposed and developed for practical applications a variety of gear-mesh type automatic transmissions employing gear-mesh type transmissions. By way of example, in the control apparatus for the gear-mesh type automatic transmission system disclosed in Japanese Patent Application Laid-Open Publication No. 270252/1988 (JP-A-63-270252), the output torque or power of an engine such as an internal combustion engine is inputted to a gear-mesh type automatic transmission through coupling operation (on-operation) of an electromagnetic clutch.
Further, in the case of the control apparatus described in the publication cited above, combination of operations of a pair of hydraulic/electromagnetic valves is adopted. More specifically, selection of a desired or target speed stage is realized by driving or actuating correspond-ingly a selection-dedicated three position hydraulic cylinder while changeover to the selected speed stage is realized by actuating a three position hydraulic cylinder dedicated for the gear shift operation.
Further, as a conventional clutch control unit known heretofore, there may be mentioned one disclosed, for example, in Japanese Patent Application Laid-Open Publication No. 35633/1985 (JP-A-60-35633). In this known clutch control apparatus, an electromagnetic clutch is so controlled that coupling thereof is carried out at a constant speed or rate. In that case, the clutch on/off performance of the apparatus will gradually change as a function of time lapse due to deterioration (abrasion) which the clutch undergoes during operation thereof.
Consequently, for a same clutch exciting current, there arises difference in the clutch coupling operation performance between a new electromagnetic clutch and a used one.
In particular, in the case where the clutch is coupled through a constant-speed control (open-loop control), there is a tendency that shock is more likely to take place upon coupling of the clutch in succession to speed stage changeover as the deterioration (abrasion) of the clutch gets aggravated even if occurrence of such shock can be controlled to be suppressed for the new clutch.
Furthermore, the clutch coupling force may differ from one to another electromagnetic clutch. Thus, for performing the open loop control mentioned above, it is necessary to determine in advance the clutch coupling speed in consideration of the intrinsic performance of the clutch to be employed so that the shock occurring upon clutch coupling operation succeeding to the speed stage changeover operation can be suppressed or mitigated at the least.
As is apparent from the foregoing, the conventional gear-mesh type automatic transmission system suffers a problem that shock may occur upon coupling of the clutch in succession to the speed changeover operation of the transmission due to the time-dependent deterioration such as abrasion of the clutch.
Further, for effectuating the open loop control, the clutch coupling speed has to be determined in advance in consideration of dispersion of the coupling force among the individual electromagnetic clutches so that occurrence of the shock upon clutch coupling operation succeeding to the speed stage changeover of the transmission can be suppressed, giving rise to another problem.
SUMMARY OF THE INVENTION
In the light of the state of the art described above, it is an object of the present invention to provide a gear-mesh type automatic transmission system capable of suppressing or mitigating shock which is likely to occur upon coupling of a clutch in succession to changeover of speed stage regardless of time-dependent deterioration or abrasion of the clutch.
Another object of the present invention is to provide a gear-mesh type automatic transmission system capable of controlling the clutch coupling speed so as to mitigate shock which is likely to occur upon clutch coupling operation succeeding to changeover of speed stage of the gear-mesh type transmission in spite of dispersion among individual clutches.
In view of the above and other objects which will become apparent as the description proceeds, there is provided according to a general aspect of the present invention a gear-mesh type automatic transmission system which includes a gear-mesh type transmission for outputting an output power of an engine at a selected gear ratio, an electromagnetic clutch for effectuating transmission and interruption of the output power from an output shaft of the engine to an input shaft of the gear-mesh type transmission, a shift/select actuator for shifting a speed change gear to a shift/select position in the gear-mesh type transmission, a shift/select position sensor for detecting a shift/select position of the speed change gear in the gear-mesh type transmission, and a control unit for driving the shift/select actuator in accordance with a shift lever position selected by a driver while monitoring the shift/select position, to thereby change over automatically the gear-mesh type transmission to a desired speed stage, wherein the control unit is designed to couple the electromagnetic clutch while carrying out a feedback control on the basis of a rate of change of rotation speed of the engine in succession to the speed stage changeover of the gear-mesh type transmission.
In a preferred mode for carrying out the invention, a plurality of control subperiods may be provided for the control unit in conjunction with coupling of the electromagnetic clutch, wherein a target engine speed change rate may be set for each of the plural control subperiods, for thereby effectuating feedback control of a command current value for the electromagnetic clutch.
In another preferred mode for carrying out the invention, condition for termination may be set for each of the plural control subperiods, wherein the control unit may preferably be so designed that every time the condition for termination is satisfied, the feedback control is caused to transit to a succeeding one of the plural control subperiods in a sequential manner.
In yet another mode for carrying out the invention, the control unit should preferably be so designed as to cause a first control subperiod to make transition to a second control subperiod when a predetermined time has lapsed in the first control subperiod immediately in succession to changeover of the speed stage of the gear-mesh type transmission, while when difference between the engine rotation speed and an input shaft rotation speed of the gear-mesh type transmission in the second control subperiod becomes smaller than a predetermined value inclusive, transition is made from the second control subperiod to a third control subperiod.
In still another mode for carrying out the invention, the control unit should preferably be so designed as to determine arithmetically a command current value for the electromagnetic clutch through an open loop control in a last control subperiod succeeding to the plural control subperiods.
In a further mode for carrying out the invention, the control unit should preferably be so designed that when condition for terminating the last control subperiod is satisfied, processing for completing coupling operation of the electromagnetic clutch is executed.
In a yet further mode for carrying out the invention, the control unit should preferably be so d
Kramer Devon
Mitsubishi Denki & Kabushiki Kaisha
Schwartz Christopher P.
Sughrue & Mion, PLLC
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