Kabushiki Kaisha Riken

Riken Corporation

Yukio Nakanouchi

Masaharu Hasei

Hideyuki Kurosawa

Akira Kunimoto

Yongtie Yan

Yunzhi Gao

Kazuhiro Takahashi

Takashi Ono

Tetsuo Uchiyama

Norio Miura

Noboru Yamazoe

Fumio Kiyota

A gas sensor for measuring concentration of a gas component in a measured gas, including a solid electrolytic substrate and at least two electrodes fixed to the substrate. At least a first electrode of the electrodes is disposed in the environment of the measurement gas, at least one of electrodes is polarized by applying a bias current or bias voltage, and a change in the potential of the polarized electrode is measured to thereby measure the concentration of the target gas.

Measuring NOx concentration

A nitrogen oxide sensor includes a solid electrolytic substrate exhibiting oxygen ion conductivity, a noble-metal reference electrode, which is active only to oxygen, formed on one side of the solid electrolytic substrate, and a sensing electrode, which is active to NOx and oxygen, formed on the opposite side of the solid electrolytic substrate. A potential difference across the sensing electrode and the reference electrode is output as a signal indicative of NOx concentration. Nitrogen oxides in a gas to be examined or measured gas are converted to NO,and to peroxides of nitrogen such as N,O,and NO,, after which the nitrogen oxides in the gas to be examined or measured gas are sensed by the sensing electrode as the peroxides of nitrogen such as N,O,and NO,or as a mixed gas of NO,and the peroxides of nitrogen.

Gas sensor

A stable sensor designed to detect accurately the total NOx concentration under 100 ppm in terms of the NO gas concentration is made up of a first cell and a second cell with a gas diffusion aperture provided between the two cells. The first cell has a partition wall of a substrate of oxygen ion conductor containing zirconia as the main component and permitting a gas to be detected to enter the zirconia substrate; oxygen pumping electrodes are also formed on the first cell substrate which functions to expel oxygen in an atmosphere of the first cell to the outside and to reduce NO.sub.2 of the NOx gas to be detected to NO gas. While NO gas entering through a gas diffusion aperture between the two cells flows into the second cell, a measurement is made of an electromotive force between a NO detection electrode formed in the second cell and a counter electrode also formed therein or a counter electrode formed on the reverse side of the zirconia substrate, since such electromotive force corresponds to the level of the NO gas concentration and thus provides the total NOx concentration.

NOx sensor

The present invention discloses a NO.sub.x sensor consisting at least of a pair of the first and the second electrodes formed in touch with an oxygen conductive solid electrolyte; wherein at least the first elelctrode is composed of oxides of an element selected from 7a Group or 8 Group, especially from Mn, Fe, Co, and Ni or a substance containing said oxides or of hybrid oxides (including the one of oxygen deficiency expressed by ABO.sub.3, AB.sub.2 O.sub.4, A.sub.2 BO.sub.4 and ACBO.sub.4 including 7a Group and 8 Group. A NO.sub.x sensor acording to the present invention has a good sensitivity without being affected by the concentration of CO.sub.2 and detects NO.sub.x concentration in an exhaust gas at a temperature above 600.degree. C.

NO.sub.x sensor

A method and a detector for detecting nitrogen oxide in test gas are provided wherein test gas which contains NOx and interference gases is supplied through an oxygen feeder 4 into a measuring chamber 1a, and the interference gases are oxidized by oxygen or oxygen ion supplied to the measuring chamber 1a through oxygen feeder 4. A total amount of NOx in the test gas is detected based on a level of EMF produced between a first electrode 2 for detecting oxygen and NO2 gas and a second electrode 3 for detecting oxygen.

Nitrogen oxide detector

A limiting current-type oxygen sensor including (a) a pair of oxygen ion-permeable substrates made of a zirconia solid electrolyte; (b) at least one diffusion pore provided in at least one of the substrates, which extends substantially along the thickness of the substrate for causing oxygen diffusion through the diffusion pore to be a rate-determining step; (c) a sealing member for fixing the pair of substrates such that a closed chamber is defined between the substrates; and (d) a pair of porous electrodes provided on both outer and inner surfaces of each electrode.

Limiting current-type oxygen sensor

A limiting current-type oxygen sensor including (a) an oxygen ion-permeable substrate made of a zirconia solid electrolyte having a gas diffusion pore extending between first and second surfaces of the substrate for rate determination by oxygen diffusion through the pore; (b) a first porous electrode formed on the first surface of the substrate in an area including an opening of the gas diffusion pore; (c) a second porous electrode formed on the second surface of the substrate such that it is opposite to the first porous electrode via the substrate; (d) a sealing member fixed to the second surface of the substrate for sealing the second porous electrode such that the internal chamber is defined on the second porous electrode; and (e) a heating means mounted to the sealing member.

Growing community of inventors

Kumagaya, Japan

Yukio Nakanouchi