Electricity: electrical systems and devices – Control circuits for electromagnetic devices – Including compensation for thermal change of electromagnetic...
Reexamination Certificate
2000-04-17
2001-11-06
Huynh, Kim (Department: 2836)
Electricity: electrical systems and devices
Control circuits for electromagnetic devices
Including compensation for thermal change of electromagnetic...
C123S568310, C361S161000
Reexamination Certificate
active
06313977
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to a circuit configuration for regulating a current fed to an electromechanical component of an automobile.
A circuit configuration of this type serves for regulating the current fed to the electromechanical component in the motor vehicle in particular a coil current for a hydraulic pressure regulating valve of an automatic motor vehicle transmission. It has a circuit carrier containing conductor tracks and components for controlling the electromechanical component, and also a current measuring resistor, whose signal is evaluated during the current regulation.
A device for detecting a load current is known from Published, Non-Prosecuted German Patent Application DE 42 23 338 A1, to be precise, a regulator with overload protection. A signal derived from a current measuring resistor and a reference signal are fed to an operational amplifier. The current measuring resistor is configured as a conductor track of a printed circuit. The reference signal is applied to a second input of the operational amplifier via a further conductor track. The two conductor tracks are constructed identically and are in good thermal contact. As a result, the load current is detected in a temperature-compensated fashion.
In the case of error compensation for measuring instruments, the measured values of the latter are calculated in a microcomputer as is known in German Patent DE 26 30 958 B2. The microcomputer is assigned memories in which are stored correction values, correction curves of reference quantities and of components, temperature coefficients, temperature profile curves and aging rates of the reference quantities and components. The correction values are measured using an analog-to-digital converter dedicated to the measuring instruments, and therefore contain this error as well. The measuring instruments register the time that has elapsed since a measuring instrument was used, and all of the stored correction values are taken into account in the calculation of the final measured values. The output signal of a temperature sensor and the stored temperature coefficients and curves are also taken into account in the calculation.
In the case of current regulators subjected to high temperature fluctuations, it is customary to bond a current measuring resistor made of constantan or a similar high-quality alloy on that side of the circuit carrier which bears the components, and to make contact with it by bonding wires. Although this enables accurate current measurement in a wide temperature range, such precision current measuring resistors are nonetheless expensive.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a circuit configuration for regulating the current fed to an electromechanical component in a motor vehicle that overcomes the above-mentioned disadvantages of the prior art devices of this general type, which is a cost-effective and space-saving circuit configuration for current regulation.
With the foregoing and other objects in view there is provided, in accordance with the invention, a circuit configuration for regulating a current fed to an electromechanical component in a motor vehicle, including a coil current for a hydraulic pressure regulating valve of an automatic motor vehicle transmission. The circuit configuration includes a ceramic circuit carrier with conductor tracks disposed on the circuit carrier. Components are disposed on the circuit carrier for controlling the electromechanical component. A current measuring resistor is applied on the circuit carrier as a thick-film resistor. The current measuring resistor has a temperature-dependent resistance and outputs a first signal for evaluation during a current regulation process. Also included is a temperature sensor for detecting a transmission oil temperature. The sensor is thermally coupled to the current measuring resistor and is applied on the carrier circuit. The temperature sensor outputs a second signal. A control unit receives the first signal and the second signal and uses the second signal from the temperature sensor for compensating for the temperature-dependent resistance of the current measuring resistor.
In accordance with a further feature of the invention, there are provided further printed resistors. The components are applied on one side of the circuit carrier and the current measuring resistor and the further printed resistors are applied on an opposite side of the circuit carrier.
In accordance with an added feature of the invention, the temperature sensor is a negative temperature coefficient (NTC) thermistor.
In accordance with a concomitant feature of the invention, the current measuring resistor is a plurality of current measuring resistors, and the temperature sensor is a single temperature sensor provided to compensate for a temperature profile of the plurality of current measuring resistors.
The particular advantages of the invention are that a costly precision resistor is replaced by a current measuring resistor that is simple and cost-effective since it is printed onto the circuit carrier. Since the current regulator has not only the components for controlling the electromechanical components but also a series of resistors which are part of a printed circuit, the resulting manufacture is highly economical since the current measuring resistor can be concomitantly printed on at the same time. The outlay for mounting and making contact with the precision resistor is obviated, and the required material is inexpensive. Furthermore, mounting space on that surface of the circuit carrier that bears the discrete components becomes free.
On the other hand, the printed current measuring resistor supplies markedly temperature-dependent measured values, which must be compensated. This is achieved in a very simple manner by virtue of the fact that the signal of the temperature sensor is used for compensation purposes in a control unit, the temperature sensor being present in any case in the circuit configuration and being applied, in particular, on the circuit carrier itself.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a circuit configuration for regulating the current fed to an electromechanical component in a motor vehicle, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
REFERENCES:
patent: 4264961 (1981-04-01), Nishimura et al.
patent: 4266257 (1981-05-01), Rudich, Jr.
patent: 4379520 (1983-04-01), Tomsu
patent: 4612895 (1986-09-01), Kuroiwa et al.
patent: 4836174 (1989-06-01), Chujo et al.
patent: 5123081 (1992-06-01), Bachman et al.
patent: 5146907 (1992-09-01), Sawazaki et al.
patent: 5159532 (1992-10-01), Kilian et al.
patent: 5585995 (1996-12-01), Baurand et al.
patent: 2630958 (1978-07-01), None
patent: 3811670A1 (1989-10-01), None
patent: 4223338A1 (1994-01-01), None
“Thick-Film Thermistor and Its Application”, Akira Ikegami et al., IEEE Transactions on Components, Hybrids and Manufacturing Technology, No. 4, Dec. 1980, pp. 542-547.
Japanese Patent Abstract No. 5135908 (Takeshi et al.), dated Jun. 1, 1993.
Greenberg Laurence A.
Huynh Kim
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
LandOfFree
Circuit configuration for regulating the current fed to an... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Circuit configuration for regulating the current fed to an..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Circuit configuration for regulating the current fed to an... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2616773