Oxygen sensor

Claim 2

An oxygen sensor Including a cylindrical oxygen sensing element (11), the oxygen sensing element (11) having one closed end and inner and outer electrode layers (12, 13) formed on the inner and outer surfaces thereof respectively, and an output lead wire (14) electrically connected to the Inner electrode layer (12) of the oxygen sensing element (11), characterised in that a metallic terminal (21) Is provided between the output lead wire (14) and the inner electrode layer (12) and having a portion (21a, 121a) urged radially Into contact with the Inner periphery of the Inner electrode layer (12).

Claim 3

An oxygen sensor including: (a) an oxygen sensing element (11) having one electrolyte; (b) an inner electrode layer (12) formed of platinum on the inner surface of the oxygen sensing element (11); (c) an outer electrode layer (13) formed of platinum on the outer surface of the oxygen sensing element (11); (d) an output lead wire (14) electrically connected to the inner electrode layer (12) for withdrawing the output of the latter; and (e) a metallic terminal (21) for connecting the inner electrode layer (12) of the oxygen sensing element (11) with the output lead wire (14), characterised in that.said metallic terminal (21) has a connecting portion (21a) formed by bending a spring steel sheet so as to exhibit a resilient force in a radial direction, the connecting portion (21a) being inserted under application of a compressive force into an opening (lla) of the oxygen sensing element (11) and then released thereby being fixed in pressure contact and electrical connection with the inner electrode layer (12) formed on the inner surface of the opening (lla) of the oxygen sensing element.

Claim 4

An oxygen sensor including: (a) an oxygen sensing element (11) having one electrolyte; (b) an inner electrode layer (12) formed of platinum on the inner surface of the oxygen sensing element (11); (c) an outer electrode layer (13) formed of platinum on the outer surface of the oxygen sensing element (11); (d) an output lead wire (14) electrically connected to the inner electrode layer (12) for withdrawing the output of the latter; and (e) a metallic terminal (21) for connecting the inner electrode layer (12) of the oxygen sensing element (11) with the output lead wire (14), characterised in that.said metallic terminal (21) has a connecting portion (21a) formed by bending a spring steel sheet so as to exhibit a resilient force in a radial direction, the connecting portion (21a) being inserted under application of a compressive force into an opening (lla) of the oxygen sensing element (11) and then released thereby being fixed in pressure contact and electrical connection with the inner electrode layer (12) formed on the inner surface of the opening (lla) of the oxygen sensing element.

Claim 5

An oxygen sensor as claimed in claim 1 or claim 2, further including a cylindrical housing (15) for holdingthe oxygen sensing element (11), the housing (15) being electrically connected to the outer electrode layer (13), and a protector (20) attached to a combustion apparatus-side fore end portion (15c) of the housing (15) for protecting the oxygen sensing element (11), the protector (20) having a plurality of exhaust gas passing holes (20a) for allowing exhaust gases to come into contact with the outer electrode layer (13).

Claim 6

An oxygen sensor as claimed in claim 3, in which the housing (15) has a screw-threaded portion (15a) formed on the outer periphery thereof for mounting the oxygen sensor to a combustion apparatus and a caulking portion (15b), and a gasket (16) for preventing the leakage of exhaust gases is provided on the portion of the housing (15) to be brought into abutment with a wall surface of the combustion apparatus, and by caulking the caulking portion (15b) the oxygen sensing element (11) is held by the housing (15) through a plate packing (17), talc (18), caulking ring (19) and outer tubular shell flange portion (22a) which are disposed on the inner periphery of the housing (15).

Claim 7

An oxygen sensor as claimed in claim 1 or claim 2, in which the metallic terminal (21) and the output lead wire (14) are connected by pressure bonding together a terminal portion (21b) and core (14a) of the lead wire (14), and are protected by a protective sleeve (25) which is co-axially fixed directly or indirectly to a cylindrical housing (15) for holding the oxygen sensing element (11), the protective sleeve (25) having a seal member (24) with the lead wire (14) being inserted therethrough, the seal member (24) being fixed to an end portion of the protective sleeve (25).

Claim 8

An oxygen sensor as claimed in any preceding claim, in which the metallic terminal (21) is formed by punching a metallic plate to form a connecting portion (21a) and a terminal portion (21b) provided at an end of an elongated extension extending from the connecting portion (21a), the connecting portion (21a) being formed cylindrically by bending the metallic sheet.

Claim 9

An oxygen sensor as claimed in any one of claims 1 to 5, in which the metallic terminal (21) is obtained by forming wavy notches in a nearly rectangular metallic sheet and then bending the metallic sheet cylindrically.

Claim 10

An oxygen sensor as claimed in any one of claims 1 to 5, in which the metallic terminal (21) is obtained by forming rectangular notches in a rectangular metallic sheet and then bending the metallic sheet cylindrically.

Claim 11

An oxygen sensor as claimed in any preceding claim, in which the oxygen sensing element (11) is maintained at a predetermined temperature by means of a heater (130), and the output lead wire (14) and the inner electrode layer (12) are connected through a metallic terminal (21) which is fixed in pressured contact with the inner periphery of the inner electrode layer (12) and which holds the heater (130).

Claim 12

An oxygen sensor including: (a) an oxygen sensing element (111) having one closed end and cylindrically formed of a solid electrolyte; (b) an inner electrode layer (112) formed of platinum on the inner surface of the oxygen sensing element (111); (c) an outer electrode layer (113) formed of platinum on the outer surface of the oxygen sensing element (111); (d) an output lead wire (114) electrically connected to the inner electrode layer (112) for withdrawing the output of the latter; (e) a metallic terminal (121) for connecting the inner electrode layer (112) of the oxygen sensing element (111) with the output lead wire (114); characterised in that there is provided a rod-like ceramic heater (130) for heating the oxygen sensing element (111), the ceramic heater (130) being disposed in the interior of the oxygen sensing element (111), and said metallic terminal (121) has a connecting portion (121a) formed by bending a spring steel sheet so as to develop a resilient force in a radial direction, a heater holding portion (121b) also formed by bending the spring stell sheet to resiliently hold the ceramic heater (130) inserted therethrough, and a terminal portion (121d) capable of being connected to the core of the output lead wire (114) by pressure bonding or by soldering.

Claim 13

An oxygen sensor including: (a) an oxygen sensing element (111) having one closed end and cylindrically formed of a solid electrolyte; (b) an inner electrode layer (112) formed of platinum on the inner surface of the oxygen sensing element (111); (c) an outer electrode layer (113) formed of platinum on the outer surface of the oxygen sensing element (111); (d) an output lead wire (114) electrically connected to the inner electrode layer (112) for withdrawing the output of the latter; (e) a metallic terminal (121) for connecting the inner electrode layer (112) of the oxygen sensing element (111) with the output lead wire (114); characterised in that there is provided a rod-like ceramic heater (130) for heating the oxygen sensing element (111), the ceramic heater (130) being disposed in the interior of the oxygen sensing element (111), and said metallic terminal (121) has a connecting portion (121a) formed by bending a spring steel sheet so as to develop a resilient force in a radial direction, a heater holding portion (121b) also formed by bending the spring stell sheet to resiliently hold the ceramic heater (130) inserted therethrough, and a terminal portion (121d) capable of being connected to the core of the output lead wire (114) by pressure bonding or by soldering.

Claim 14

An oxygen sensor as claimed in claim 10, in which the ceramic heater (13) is tubular and is made by winding around a green ceramic core formed in an elongated tube shape a green ceramic sheet with a predetermined shape of a heater pattern of a metal having high melting point printed on one face and bringing the ceramic sheet into close contact with the ceramic core, then forming on the surface of one side thereof printed faces of said metal serving as connecting terminal faces electrically connected to both ends of the buried pattern followed by burning.

Claim 15

An oxygen sensor as claimed in claim 11, in which the metal comprises at least one ingredient selected from the group consisting of platinum, tungsten and molybdenum.

Claim 16

An oxygen sensor as claimed in claim 10, further including heater lead wires (140, 141) respectively connected by pressure bonding or by soldering to heater terminals (150, 151) which are connected by soldering to terminal faces of the heater (130).

Claim 17

An oxygen sensor as claimed in claim 10, in which the connecting portion (121a) is inserted into an inlet opening portion somewhat expanded in inside diameter of the oxygen sensing element (111) under application of a compressive force and while holding the heater and then released whereby the connecting portion (121a) is fixed in pressure contact with the inner electrode layer (112) formed on the inner surface of said inlet opening portion to thereby hold said ceramic heater in a predetermined position and at the same time electrically connected to the inner electrode layer (112), and the core of the output lead wire (114) is connected to the terminal portion (121d) of the metallic terminal (121) by pressure bonding or by soldering.

Claim 18

An oxygen sensor as claimed in claim 13, further including a protective sleeve (125) co-axially fixed directly or indirectly to a cylindrical housing for holding the oxygen sensing element, said protective sleeve having a seal member (124), the seal member being fixed to an end portion of the protective sleeve (125).

Claim 19

An oxygen sensor as claimed in claim 13, further including a tubular shell (122) extending from and fixed to a housing for holding the oxygen sensing element, and a protective sleeve (125) fitted and fixed onto a tubular shell (122), whereby a seal member (124) with leads (140, 141, 114) inserted therethrough are held in the portion between an inwardly bent edge of the protective sleeve (125) and a like edge of the tubular shell (122), and at the same time the heater - lead wire connection and the metallic terminal - lead wire connection are protected.

Claim 20

An oxygen sensor as claimed in claim 10, in which the metallic terminal (121) is obtained by punching a metallic sheet so as to form the connecting portion (121a) centrally, two holding portions (121b) formed on both sides of the connecting portion (121a) through notches (121c) and the terminal portion (121b) at an elongated end extending from one holding portion (121b), the connecting portion (121a) being round in the form of a cylinder having an inside diameter larger than that of an opening portion (llla) of the oxygen sensing element, the holding portions (121b) being round in the form of a cylinder having an inside diameter smaller than the outside diameter of the heater, the thus rounded connecting portion (121a) and holding portions (121b) being aligned with each other by forming bent portions (121e), the heater (130) being inserted through the heater holding portions (121b) and thereby held by the metallic terminal (121) and further fixed in the interior of the oxygen sensing element (111) by inserting the connecting portion (121a) into the oxygen sensing element.