Data processing: generic control systems or specific application – Generic control system – apparatus or process – Optimization or adaptive control
Reexamination Certificate
1999-03-22
2002-08-13
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Generic control system, apparatus or process
Optimization or adaptive control
C700S028000, C701S051000, C192S003560, C477S048000
Reexamination Certificate
active
06434434
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to control transmissions with hydraulic and mechanical gearing, especially transmissions which are used in commercial utility vehicles.
2. Description of the Related Art
All gear shifts should be smooth under load, regardless of the type of engine or differential transmission that is being applied. These requirements for a transmission control unit are best addressed with an electrohydraulic control system whose operating principle is described in the technical publication “Hydrodynamik in der Antriebstechnik”, published by J. M. Voith GmbH, Vereinte Fachverlage Krauskopf-Ingenieur Digest, Mainz, 1987, in the German Patent Document No. DE 36 07 329, or in the paper by M. Bek, “Elektronisches Steuerungssystem fuer Automatgetriebe” Voith research and design, paper 33 (1989), Voith print G 1225 (3.89).
The control system, known from German Patent Document No. DE 36 07 329, is designed for multi-gear power shift transmissions for motor vehicles and includes pressure-actuated clutch elements in the form of either brakes or clutches which are used to engage and change the individual gears. The pressure supply to each of these clutch elements is controlled by a control valve. Furthermore, a control system is provided which determines the shift patterns of the transmission depending upon the various operating conditions, such as rotational input speed and/or rotational output speed of the transmission and the throttle position of the fuel system. The electrohydraulic control system known from the German Patent Document No. DE 36 07 329 is characterized by a control valve which is designed to combine the functions of an electromagnetic shift valve and a pressure regulator valve. The force exerted on the valve body, and causing the movement of same, by the electromagnet's armature is adjustable by varying the strength of the magnetic field. The electromagnet is provided with a device for the formation of a measuring voltage which is proportional to the time-based change of induction, for the purpose of determining a measured variable (responsible for establishing the actual value) which, in turn, is needed for the instantaneous magnetic induction and the subsequent formation of the magnetic force. Connected to the device is at least one integral element which converts the measuring voltage into the measured variable that is proportional to the induction. Furthermore, a control element is provided to form a manipulated value for the exciting current for the electromagnet, by comparing the actual value derived from the integral element with the set point value provided by the control system. Thus, the magnetic force and the subsequent pressure on the hydraulic fluid acting upon the clutch elements is adjusted to the value corresponding to the set point value. Finally, a time element is provided which imposes a time-based limit on the control process at the initiation of a shift action of the transmission so that, subsequently, the actual value and/or the set point value assume a minimum or maximum value.
Electronic control system for such actuators, applied as solenoid valves for electro-hydraulic applications, are extensively described in M. Bek, “Elektronisches Steuerungssystem”, Voith research and design, paper 33 (1989), Voith Druck G 1225 (3.89), the disclosure of which is fully incorporated by reference herein. The electrohydraulic control system from the above publication takes advantage of the relationship between the control pressure p of the hydraulic system and the force F
m
of the electromagnet as described in the following equation:
p=F
m
/A
k
whereby A
k
is the effective area of the control piston. On the other hand, the force exerted by an electromagnet, assuming a small air gap, is approximated by this equation:
Fm≈
1/2&mgr;
0
A.&PHgr;
2
wherein:
&mgr;
0
: Permeability of air
A: Area of the air gap
&PHgr;: magnetic flux formed by the exciting current
In order to determine the actual value of the magnetic force F
m
which is required for the electronic control of the magnetic force and, thus, the control pressure p, the magnetic flux must be determined. Concerning this subject matter, the publication (M. Bek, “Elektronisches Steuerungssystem”, Voith research and design, paper 33 (1989), Voith print G 1225 (3.89), suggests introducing a measuring coil into the magnetic field of the field coil. According to the induction law, the (magnetic) flux can be obtained from the induced voltage through integration over time. The relationship between the magnetic force and the induced voltage is described as follows:
F
m
(
t
)
≈
(
∫
0
t
U
m
(
t
)
ⅆ
t
Hence, in order to obtain the actual value of the magnetic force F
m
the induced measured value absorbed by the measuring coil must be integrated.
Until now, the control of the magnetic force was performed by hardware-based analog controllers. The analog controllers were designed as discrete two-step controllers (ref. Dubbel, Reference book for mechanical engineering, Springer Verlag, Berlin, Heidelberg, New York, 1995, pages X8 through X9). The disadvantages of the analog controllers, as published in M. Bek, “Elektronisches Steuerungssystem” . . . , whose control comparators, for example, were applied in form of connected operational amplifiers, are:
Batch-to-batch variability as a result of the integration behavior of the integrators which are used for the individual determination of Fm, making it necessary to balance the circuitry of the analog two-step controller by, for example, soldering resistors onto the appropriate integrator.
When applying a multiplex operation, which is the sequential control of several solenoid valves with one and the same electronic controller, the controller can only be balanced to one integrator.
Influences of the supply voltage +U
b
on the magnetic force cannot be taken into account.
A further disadvantage of the analog controllers is the setting of the hysteresis, which is required for the stable operation of a two-step controller (ref. Dubbel, rest as stated above, page X8). The hysteresis is adjusted in these circuits by applying resistors into the circuit design, thereby making a subsequent change to the hysteresis value no longer feasible.
Further, the hardware circuitry assigns a discrete manipulated output value for every actual input value. This rigid relationship does not permit the control of two solenoid valves with one and the same controller.
SUMMARY OF THE INVENTION
With the present invention, the chosen gear befits the vehicle speed and engine load so that optimum engine operating conditions and driveability characteristics can be achieved all times, even under varying driving conditions.
The present invention provides an electronic control system for an electrohydraulic controller of a power shift transmission, as well as establishes a process for controlling such a transmission. The control system overcomes the above-stated disadvantages associated with the state of the art.
An electrohydraulic control system with electronic control for a transmission includes at least one actuator element, a device to accept a measured signal from one actuator element, or a device to accept a plurality of measured signals if one and the same electronic control system serves several actuator elements. The electronic control system further includes a device to form an actual value of the actuator element(s) from the received analog measured signal. This measured signal is used for the control of the actuator element(s). The electronic control system includes an A/D converter, which, in a first embodiment, is connected between the analog actual value generator and the processor, and serves to convert the analog actual value of the actuator elements into a digital actual value. This digital actual value is subsequently fed into a computing system, preferably a microprocessor. Alternatively, the A/D converter can be arranged to be ahead of a digital
Bek Manfred
Dietzel Bernd
Frank Elliot
Picard Leo
Taylor & Aust P.C.
Voith Turbo GmbH & Co. KG
LandOfFree
Electronic control for a transmission control system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electronic control for a transmission control system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electronic control for a transmission control system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2942671