Chemistry: electrical and wave energy – Apparatus – Electrolytic
Patent
1997-01-13
1998-11-17
Bell, Bruce F.
Chemistry: electrical and wave energy
Apparatus
Electrolytic
204427, 123672, 123693, 123694, 123703, G01N 2726
Patent
active
058371141
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/DE96/00611 filed Mar. 29, 1996.
FIELD OF THE INVENTION
The invention relates to an arrangement for determining the concentration of a component in a gas mixture. The invention is especially related to measurement sensors which are utilized for controlling the composition of the air/fuel mixture of internal combustion engines. Sensors of this kind detect the oxygen content in the exhaust gas of the engine and supply an input signal for a control loop to control the mixture composition to pregiven values.
BACKGROUND OF THE INVENTION
The subject matter of the invention is an arrangement which is configured, in principle, as a universal oxygen probe described in SAE Paper 920234.
A probe of the type disclosed therein has a first component volume in which the concentration of oxygen is coupled via a diffusion resistance to the concentration of oxygen in the exhaust gas. An atmosphere having a reference oxygen concentration is present in a second component volume. A Nernst cell is mounted between the first and second component volumes and supplies an output signal characteristic of the difference of the oxygen concentrations in the two component volumes. A deviation of the oxygen concentration in the first volume, which is coupled to the exhaust gas, from a desired value is determined by comparing this output signal to a pregiven value. An oxygen pump device pumps oxygen particles into the first component volume or pumps oxygen particles out of this first component volume at a flow intensity which is dependent upon the determined deviation so that the oxygen concentration can there be held constant against the influence of the coupling to the oxygen concentration in the exhaust gas with the coupling acting via the diffusion resistance.
The variable which is to be determined, namely the oxygen concentration in the exhaust gas, can be determined by evaluating the pump current Ip.
An advantage of oxygen probes of this type is the approximately linear characteristic line Ip=f(lambda) which results when there is a slow continuous change of the mixture composition lambda. If the mixture composition is however modulated more rapidly as is conventional for the mixture control for engines, a hysteresis in the characteristic line results at lambda=1. Stated otherwise, the value of the output signal of the sensor in the vicinity of lambda=1 is dependent upon the direction of the change of the mixture composition.
SUMMARY OF THE INVENTION
The object of the present invention is to eliminate these hysteresis effects and provide a sensor of the above-mentioned type having a characteristic line which does not exhibit disturbing hysteresis effects.
This object is solved by providing an arrangement for determining the concentration of a component in a gas mixture, the arrangement having a first volume in which the concentration of the component is held constant with respect to the influence of the coupling to the concentration in the gas mixture, the coupling acting via a diffusion resistance; the above-mentioned influence of the coupling is compensated by a controllable flow of ions of the component through a solid electrolyte between the first volume and the gas mixture so that a measure for the above-mentioned flow defines a measure for the wanted concentration in the gas mixture, the solid electrolyte functioning as a pump device; the above-mentioned flow is controlled as a function of the deviation of the output voltage of a Nernst cell and a desired value, the Nernst cell being between the first volume and a reference gas volume; and, means are provided which influence the above-mentioned desired value in a targeted manner as a function of the voltage which can be measured across the solid electrolyte of the pump device.
The use of the arrangement of the invention especially increases the accuracy of control loops having a continuous dependency of the position variable from the control deviation in the range which is essential for the conversion of toxic materials when there is a st
REFERENCES:
patent: 4622126 (1986-11-01), Shimomura
patent: 4658790 (1987-04-01), Kitahara
patent: 4772376 (1988-09-01), Yukawa et al.
patent: 5236569 (1993-08-01), Murase et al.
patent: 5338431 (1994-08-01), Yorita et al.
patent: 5366610 (1994-11-01), Hirako et al.
patent: 5391284 (1995-02-01), Hotzel
patent: 5549804 (1996-08-01), Hotzel et al.
patent: 5558752 (1996-09-01), Wang et al.
"Universal Air-Fuel Ratio Heated Exhaust Gas Oxygen Sensor and Further Applications" by T. Yamada et al, SAE Technical Paper Series 920234, International Congress & Exposition, Detroit, MI, Feb. 24-28, 1992.
Bell Bruce F.
Ottesen Walter
Robert & Bosch GmbH
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