Electricity: measuring and testing – Electrical speed measuring – Including speed-related frequency generator
Patent
1989-04-12
1991-07-02
Snow, Walter E.
Electricity: measuring and testing
Electrical speed measuring
Including speed-related frequency generator
32420712, 32420715, 32420725, G01P 348, G01P 354, G01B 714
Patent
active
050292862
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a pulse shaper for inductive pickups particularly for speed pickups or angle of rotation pickups at internal combustion engines.
A device for the generation of a speed-dependent signal sequence from the periodic voltage of an inductive pickup arrangement for angle of rotation sensing on an internal-combustion engine is known from German Patent Specification No. 3,127,220. The pickup voltage is fed to a threshold stage. To reduce the self-adjustment, means are provided which shift the pickup voltage for feeding to the threshold stage amplitude-dependently in such a way that the switching point of the threshold stage is fixed as a function of the angle of rotation. The amplitude shift is divided into a negative and positive amplitude shift. For both shift components, integration capacitors are provided which are reconnected to the pickup via diodes. Connected in parallel to the capacitors are resistors which serve to set a defined discharge of the integration capacitors.
It is disadvantageous in the case of the device known from German Patent Specification No. 3,127,220 that the inductive pickup has to be capable of providing the charging currents for the integration capacitors. The necessary currents are additionally increased by the resistors connected in parallel with the integration capacitors. A further disadvantage is that the diodes and the integration capacitors are subjected to high voltages, which may amount to several 100 volts, if the inductive pickup is a speed pickup on an internal-combustion engine which has to cover a large speed range. A high operating voltage, however, requires voluminous and expensive capacitors.
ADVANTAGES OF THE INVENTION
The pulse shaper acording to the invention allows, with a low expenditure on circuitry, an adaptation of a highly fluctuating input level to a predeterminable level and consequently a suppression of shifts over time of the pickup signal. In comparison with known pulse shapers, it has the advantage that the high voltage delivered by the inductive pickup only occurs at an ohmic resistor arranged at the input of the pulse shaper. The integration capacitor used in the pulse shaper and all other components of the pulse shaper are subject to no more than the operating voltage of the pulse shaper. The resistor at the input of the pulse shaper forms with diodes a voltage divider which has the special advantage that a change in the diode voltage makes possible a change in the voltage divider ratio. For this purpose, controlled voltage sources are provided which pick off their control signal from the integration capacitor. It is advantageous furthermore that the pickup only has to provide a low electric power output, since the previously necessary charging current of the integration capacitors is no longer needed. Consequently, the volume of the pickup can be reduced.
It is favourable if the controlled voltage source connected to the integration capacitor is designed with a differential amplifier wired as an impedance transformer and with a further differential amplifier wired as an inverting amplifier, the input signal of which is the output signal of the impedance transformer
It is further of advantage that the pulse shaper according to the invention can be produced particularly easily as an integrated circuit, as only easily integratable components are involved. This embodiment entails a considerable cost reduction for series production in the automobile industry if the pulse shaper according to the invention is used as a speed or angle of rotation pickup on internal-combustion engines.
Further details and advantageous further developments of the pulse shaper according to the invention emerge from the following description.
DRAWING
The single figure shows a circuit diagram of a pulse shaper according to the invention.
DESCRIPTION OF THE EXEMPLARY EMBODIMENT
An inductive pickup 10, not described in more detail, is connected by its first terminal 11 via a capacitor 12 to a first terminal 13 of an ohmic resistor 14. A
REFERENCES:
patent: 4475526 (1984-10-01), Schleupon
Patent Abstracts of Japan, vol. 8, No. 139, (E-253) (1576), 6/1984 (JP 59-49014.
Robert & Bosch GmbH
Snow Walter E.
Striker Michael J.
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