Electric power conversion systems – Current conversion – With condition responsive means to control the output...
Reexamination Certificate
1997-11-09
2001-01-09
Han, Jessica (Department: 2838)
Electric power conversion systems
Current conversion
With condition responsive means to control the output...
C363S049000, C323S299000
Reexamination Certificate
active
06172887
ABSTRACT:
The present invention relates to the area of engine driven machines. It relates to a circuit arrangement for the batteryless power supply of the electronic control of a machine driven by an internal combustion engine and, more particularly, to a portable machine with a rated direct voltage. The machine possesses an a.c. voltage generator driven by the internal combustion engine which delivers a generated voltage dependent upon the revolutions per minute of the internal combustion engine. The circuit arrangement comprises a first rectifier switch which converts the generated voltage into an intermediate d.c. voltage.
BACKGROUND OF THE INVENTION
A circuit arrangement of the type referred to above is known for the area of motor vehicle engineering from the German patent publication DE-A1-38 41 610.
In combustion-engine machines, electrical energy is required, for the operation of controls which typically is made available from batteries or is generated by generators driven by the engine. The employment of batteries, especially in portable machines, entails an additional expense, particularly as the long-term storage volume is limited. Moreover, in the batteryless operation as is provided in the DE-A1-38 41 610 publication for a motor vehicle, the voltage generated by the normal generator through the starting process does not provide sufficient energy for operating additional controls. However, this will be necessary in the future when engines with injection valves are more commonly used in order to actuate a valve or the like.
The applicants have designed a power supply for an electrically-controlled chain saw which dispenses additional energy. In this case, however, it did prove disadvantageous that a part of the ignition energy was used for the starting process so that, on account of the power withdrawal connected herewith, the starting behavior deteriorated. Since, in the case of portable machines, the starting behavior significantly affects operating comfort, such a solution is not devoid of problems.
Thus, an objective of the invention is to provide a circuit arrangement which permits a reliable power supply, without the employment of booster batteries, which can deliver power in the starting phase with the requisite rated d.c. voltage and which, at the same time, is simple and sturdy in its construction.
SUMMARY OF THE INVENTION
According to the invention, novel circuit arrangement comprises first means which are disposed in series with a first rectifier circuit and which generates with a low-running level of revolutions per minute, the rated d.c. voltage from an intermediatate d.c. voltage by means of controlled upward transformation for so long as the intermediate d.c. voltage is lower than the nominal d.c. voltage.
Through upward transformation, the first means are capable of generating the requisite rated d.c. voltage from the low intermediate d.c. voltages which, in the starting phase may constitute, for example, merely 20% of the rated d.c. voltage. Once the engine attains its higher idling speed it is possible to circumvent the first means to provide the rated d.c. voltage directly through speed regulation from the intermediate d.c. voltage.
According to a preferred embodiment of the invention, the first means comprise a switching controller connected to a switching controller interacting with a serially disposed inductance coil as well as a second rectifier circuit mounted in series with the same. By means of the switched mode of operation, the switching controller generates elevated voltage peaks in the inductance coil which are rectified and result in an upwardly transformed output d.c. voltage. When the rated d.c. voltage is reached at the switching controller output, the switching controller discontinues its function and the intermediate d.c. voltage is able to reach the output of the circuit arrangement via the inductance coil.
In order to ensure a constant rated d.c. voltage at higher speeds, a voltage controller is fitted preferably between the first rectifier circuit and the first means, which generates the nominal d.c. voltage from the intermediate d.c. voltage when, at higher numbers of revolutions, the intermediate d.c. voltage is higher than the nominal d.c. voltage. In addition, by preference second means are provided which bridge the switching controller when the intermediate d.c. voltage is lower than the rated d.c. voltage. Hereby a power supply operating in two stages is realized. In the starting phase, the voltage controller is bridged and the rated d.c. voltage is generated from the (lower) intermediate d.c. voltage by means of upward transformation. In the normal operating phase the switching controller is switched off and the voltage controller is interconnected so that the rated d.c. voltage is generated from the (now higher) intermediate d.c. voltage by means of speed regulation. Further embodiments become apparent from the dependent claims.
REFERENCES:
patent: 5157321 (1992-10-01), Kato et al.
patent: 5543703 (1996-08-01), Kusase et al.
patent: 38 41 610 (1990-06-01), None
Klare Hartmut
Singer Andreas
Dolmar GmbH
Han Jessica
McCormick Paulding & Huber LLP
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