Interrelated power delivery controls – including engine control – Clutch control – Condition responsive control
Reexamination Certificate
2002-04-29
2004-05-04
Lewis, Tisha D (Department: 3681)
Interrelated power delivery controls, including engine control
Clutch control
Condition responsive control
C477S174000, C477S180000, C701S067000, C701S068000
Reexamination Certificate
active
06730001
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a procedure for control and adjustment of a clutch in a stepless, automatic transmission in which an electronic control apparatus with two regulation circuits determines the adjustment of the clutch. The invention further concerns an apparatus for the execution of the procedure for the control and adjustment of a clutch in a motor vehicle transmission.
BACKGROUND OF THE INVENTION
By the term, “clutch”, within the concept of the invention, it is to be understood that a “start-up” clutch is meant. Under this classification are to be found clutches which are positioned between an internal combustion motor and an automatic transmission, also torque converter, bypass clutches as well as such clutches and brakes in automatic transmissions which can be employed both for start-up and for shifting.
In particular, the invention concerns wet start-up clutches which can be integrated into an automatic transmission. The majority of such clutches, however, are installed as a component assembly on the input side of the transmission. However, as a start-up element for an automatic stepless transmission, especially in a CVT, these wet clutches are also placed as a component assembly on the output side of the transmission.
Normally, clutches and brakes in automatic transmissions or in automatic stepped transmissions are electro-hydraulically activated, and operate independently of intervention by the shifting elements. The said clutches and brakes then perform as a gear position shifting means, or as gear change clutches in an assembly, or start-up clutches or yet as converter bypass clutches. To enable this service, usually an electronic transmission control apparatus acts specifically for an individual vehicle, while processing transmission and driving demands which are dependent upon the driving condition. These specifics can include axle gear ratios, transmission gear ratios, motor torque, motor rotation speed, throttle pedal position, or the like. The acquired data, as input, is processed in an electronic control apparatus and, by means of actuators and hydraulic valves, then converted into hydraulic control pressures designated for corresponding clutches. This latter data input would include clutch related signals, such as pressure control for pressure regulation or pressures during a gear change, and/or speed of rotation control during slip operation, all of which are transmitted to a hydraulic control apparatus and by means of actuators and hydraulic valves care converted to hydraulic control pressures for the corresponding clutch.
A procedure for the control of a start-up clutch, along with other matters, has been made known by DE 44 09 122 A1. The start-up control comprises, in this case, two phases. In a first phase, the input speed of rotation of the clutch is directed to a set-speed of rotation, wherein this set speed of rotation is determined by the driver's demand for power and a current mode of driving is determined. In the second phase, the difference between the input side and the output side speeds of rotation of the clutch is reduced to a set value of zero.
DE 39 37 976 discloses a procedure for the control of a clutch which serves for clutch non-interaction due to vibration disturbance. The slippage in the clutch changes, in this case, and is dependent upon speed-of-rotation-equalization as determined at the transmission output.
EP 0 214 989 B2 again makes known the use of a clutch integrated in an automatic transmission as a start-up element.
DE 198 40 573, of the applicant which up to now has not been published, describes a procedure for the control and regulation of a clutch in a stepless, automatic transmission for a motor vehicle according to which, the clutch control and regulation occurs during two driving conditions by means of a first control circuit. The degree of this control corresponds to the actual value of a difference in speed of rotation of the clutch. The first condition corresponds to a start-up process and the second condition corresponds to driving with a variable ratio arrangement.
From the likewise non-published DE 198 40 572 of the Applicant, a process for the control and regulation of a clutch in an automatic stepped transmission with traction interruption, that is to say, in an automatic stepped transmission which can shift in accord with the load is made known. With this method, during three conditions of driving (enumerated below), control is effected by means of a first regulating circuit. The degree of regulation, or-control, corresponds to the actual value of a difference in speeds of rotation of the clutch. The first condition of driving relates to a start-up process. The second condition of driving pertains to driving with a constant gear ratio. The third condition comes into play when load shifting, that is to say, a change of the ratio is initiated by a first into a second gear step of the automatic drive.
SUMMARY OF THE INVENTION
Given the above description of the state of the technology, the present invention has the purpose of making available a procedure for the control and regulation of a clutch in a stepless transmission for a motor vehicle along with an apparatus for the execution of said procedure for the control and regulation of a clutch, and to further develop the same with consideration given to the manifold usages of a single clutch, especially to achieve an improved quality of regulation and control-dynamics, in connection with an automatic stepped-transmission.
The object of the invention is to be found advantageously therein in that, during the first condition of driving, a first regulation circuit is employed for the control and regulation of the clutch. The degree of regulation corresponds to the actual value of the speed of rotation of the motor n_MOT_IST and corresponds to the input speed of rotation of the clutch. During the second condition of driving, a second regulating circuit is used, the degree of regulation being equivalent to the actual value of the difference in rotational speeds of the clutch dnK_IST. Finally, during the third condition of driving, the clutch is subjected to controlled values of pressure which, in turn, are influenced by various factors. The three conditions of driving correspond, in the above, to a first condition comprising a start-up procedure when under a threshold vehicle driving speed during a traction operation, a second condition marked by driving the vehicle at a speed above the start-up procedure, i.e., above a threshold driving speed with a positive or a negative torque during a traction or a compression mode, as well as driving under a vehicle threshold speed with negative torque at the output, and a third condition, wherein the start-up condition differentiates itself from the other driving conditions in that the driving speed is less than a threshold value and the vehicle motor can stall under this said threshold value.
By means of the procedure in accord with the invention, a better reaction of the transmission control advantageously is achieved in regard to load shifting, especially upon letting up on the fuel feed in the third condition since, in this case, the control still performs an empty action upon the pressure at the clutch although no adjustment takes place.
Further, the difference in speeds of rotation over the clutch is not brought back to a value of zero. The advantageous consequence of this is that a non-interaction vibration between the motor and the transmission is achieved.
In an advantageous development of the invention, the proposal is made that the change in gear ratio in a stepless automatic transmission is principally determined by a third regulating circuit, and that the first and third, or second and third regulating circuits are bound together by means of a non-interacting network, which exhibits a first and a second signal path, respectively. More advantageously, it is proposed here, that for the change of the ratio from a first to a second gear ratio, an individual regulating circuit is employed, nam
Dreibholz Ralf
Vohmann Martin
Davis & Bujold PLLC
Lewis Tisha D
ZF Friedrichshafen AG
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