Data processing: generic control systems or specific application – Specific application – apparatus or process – Mechanical control system
Reexamination Certificate
1999-08-12
2002-11-05
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Mechanical control system
C700S203000
Reexamination Certificate
active
06477446
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method of conforming to varying parameters a selected electric control current which is being supplied to a pressure regulating valve and is memorized with additional control currents in, and can be addressed and read out from, a characteristic field in dependency upon prevailing operating conditions to serve as an actual control current.
The invention further relates to apparatus for the practice of the above outlined method.
Automation of gear shifting transmissions in the power trains of motor vehicles is gaining in popularity on several grounds including an enhancement of the comfort to the occupant(s) of the motor vehicle as well as a reduction of specific fuel consumption. One of the reasons that an automatic or automated gear shifting transmission can bring about savings in fuel consumption is that one can drive more frequently in a relatively long gear; this causes the average pressure of a combustion engine to rise and its specific fuel consumption to drop.
In accordance with a simplified automation of the power train of a motor vehicle, only the clutch is automated whereas the transmission is shifted by hand. Owing to the thus enhanced shifting comfort, the operator of the motor vehicle is more likely to shift, and to shift more frequently, into so-called long gears which brings about a reduction of fuel consumption for reasons already pointed out hereinbefore.
If the power train of a motor vehicle employs a fully automatic transmission, it is of advantage (in order to achieve savings in fuel consumption) to operate with a starter clutch in lieu of with a torque converter clutch. In order to avoid excessive slip and the need for the application of very high fluid pressures, the operation of such starter clutches must be regulated with a rather high degree of accuracy. In other words, all such operational parameters (including torque, RPM and/or others) of the power train which influence the starting and the operation of hydraulic systems being utilized to operate automated clutches must be ascertained and processed with a very high degree of precision. As already mentioned above, such undertakings must ensure that the automated clutch can operate without excessive slip as well as that the hydraulic fluid being utilized to operate various units (such as cylinder-and-piston units) of the clutch need not be subjected to relatively high or very high pressures.
It is customary to employ a pressure regulating valve (e.g., a proportionally operating pressure regulating pilot valve) as a means for determining the pressure of a suitable hydraulic fluid (such as oil) which is being conveyed to and advanced from the fluid-operated components of the automated clutch. It is also known to employ a control unit having a memory for the storage of a characteristic field with information denoting a plurality of control currents serving as desired or required currents for the operation of the pilot valve under certain specific (selected) circumstances of operation of the power train. Once the proper control current in the characteristic field of the memory has been addressed, it is thereupon utilized as the desired or required current to control the adjustment (setting) of the pilot valve in order to achieve the aforementioned objects, such as savings in fuel and avoidance of the need for control fluids having very high or extremely high pressures.
In accordance with a presently known proposal, the above outlined objects or requirements concerning adjustments of the pilot valve which regulates the pressure of hydraulic fluid flowing to various hydraulically operated units of an automated clutch can be accomplished in a simple manner by storing the information which is contained in the characteristic field in the memory of the control unit in the following way: Each fluid pressure change of a predetermined magnitude brings about or corresponds to a predetermined change of control current. The changes of control current are dependent upon the selected desired regulating current, i.e., upon the respective desired pressure and the respective temperature.
The above outlined proposal is satisfactory under ideal circumstances, e.g., if one disregards changes which develop due to progressing wear upon the constituents of the power train, manufacturing tolerances, changes in the consistency and/or other parameters of the hydraulic fluid and/or deposits of foreign matter in the fluid and/or upon the mechanical constituents of the prime mover. It has been ascertained that the just enumerated (and certain other) unpredictable changes in or departures from optimum conditions can greatly and adversely influence the operation of conventional control units which regulate the pressure of fluid being supplied to the cylinder-and-piston units and/or to other hydraulically operated components of automated clutches in the power trains of motor vehicles. In other words, presently known control units and the information stored in the memories of such control units cannot ensure the absence of slip (or excessive slip) in the automated clutch and/or excessive fuel consumption if the characteristics of the aforementioned unpredictable parameters depart from optimum values. Excessive departures of actual control or regulating pressure from the desired or required pressure can greatly affect the operation of the automated clutch as well as of the entire power train.
OBJECTS OF THE INVENTION
An object of the invention is to provide a method of regulating the pressure of hydraulic fluid being supplied to and by a fluid pressure regulating valve for use in or in conjunction with automated clutches in such a way that the quality of operation of the automated clutch is not affected (or is not unduly affected) by departures of actual fluid pressures from optimum fluid pressures in spite of progressing wear upon the mechanical parts, pronounced manufacturing and/or assembling tolerances, changes in the quality of the hydraulic fluid and/or others.
Another object of the invention is to provide a method which ensures highly satisfactory operation of the automated clutch for extended portions of useful life of the power train.
A further object of the invention is to provide a method which can be practiced by resorting to a relatively simple electronic control unit as well as to available signal generating and signal transmitting monitoring devices.
An additional object of the invention is to provide a power train wherein the operation of the automated clutch can be regulated in accordance with the above outlined method.
An additional object of the invention is to provide a method which renders it possible to avoid (or at least reduce) hysteresis in the hydraulic characteristic curve of a valve for the regulation of a consumer of a pressurized hydraulic fluid.
Still another object of the invention is to reduce the differences between the actual value and the desired or required value of the pressure of hydraulic fluid being supplied to one or more cylinder-and/piston units and/or other fluid-operated constituents of automated transmissions in the power trains of motor vehicles.
A further object of the invention is to provide a method which can be resorted to in connection with the operation of power trains in motor vehicles as well as under numerous other circumstances when the pressure of hydraulic fluid being supplied to or being discharged by a pressure regulating valve must be controlled with a high or extremely high degree of accuracy under circumstances when progressing wear, manufacturing and/or assembly tolerances and/or changes in the composition of hydraulic fluid can and normally do greatly influence the operation of heretofore known and utilized pressure regulating systems.
An additional object of the invention is to provide an apparatus for the practice of the above outlined method.
Another object of the invention is to provide a relatively simple, compact, reliable and long-lasting apparatus for controlling the operation of pressure regulating valves in t
Holtmann Ludger
Homm Manfred
Ojamies Ari
Reuschel Michael
Bahta Kidest
Darby & Darby
LuK Getriebe-Systeme GmbH
Picard Leo
LandOfFree
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