The present disclosure relates generally to sensors for internal combustion engines. More specifically, the present disclosure may relate to a coupler for mechanically and/or electrically coupling a mineral insulated cable to a wiring harness that reduces moisture intrusion, provides terminal location, provides stain relief and/or increases the continuous use temperature rating.
Internal combustion engines such as, but not limited to, diesel and gasoline engines, may include one or more sensors such as, but not limited to, temperature sensors at least partially disposed within the exhaust gas system. For example, these temperature sensors may sense the temperature of the exhaust gas and may be used, at least in part, by an engine control system to adjust one or more properties of the engine such as, but not limited to, air/fuel ratio, boost pressure, timing or the like. Because of the operating environment, the temperature sensors may be exposed to relatively harsh conditions including, but not limited to, vibration, exposure to debris, moisture and corrosive chemicals, large temperature ranges and relatively high continuous use operating temperatures. The conditions may degrade the performance of the temperature sensors and may, ultimately, render the temperature sensors unsuitable for their intended purpose.
Features and advantages of the present disclosure are set forth by the description of embodiments consistent therewith, which description should be considered in conjunction with the accompanying drawings, wherein:
Referring now to the drawings,
The sensor system 10 may comprise a sensor 12 (e.g., but not limited to, a temperature sensor) coupled to a conductor housing 14, a wire harness assembly 16, and a coupler 18 configured to couple the conductor housing 14 to the wire harness assembly 16. Optionally, a connector 20 may be provided to electrically and/or mechanically couple the sensor system 10 (and in particular, the wire harness assembly 16) to a wiring loom or the like, and ultimately to at least a portion and/or subsystem of the ECU and/or ECM. The sensor 12 may be configured to output a signal representative of the parameter being detected, sensed and/or monitored. The sensor 12 may be selected depending on the intended parameter to be detected, sensed and/or monitored, the operating range, accuracy and/or precision desired. For example, the sensor 12 may comprise a temperature sensor configured to output a signal representative of the temperature of the exhaust gas, for example, the exhaust gas flowing through at least a portion of the exhaust gas system. According to at least one embodiment consistent herein, the temperature sensor 12 may include a resistive temperature detector (RTD).
The sensor system 10 may be configured to removably connect, mount, or otherwise secure the sensor 12 to a housing 13 (only a portion of which is shown for clarity) such as, but not limited to, a portion of an exhaust pipe, down pipe, exhaust manifold, or the like. For example, the sensor system 10 may include a nut 22 and optionally a stop flange 24. A portion of the sensor system 10 may be threaded to engage with a threaded aperture in the housing 13, for example, until the stop flange 24 engages the housing 13 (for example, a shoulder or the like).
Because of the relative high operating temperatures of the exhaust system 13 and the close proximity of the sensor 12 to the heat source, the sensor 12 may be electrically coupled to the wire harness assembly 16 or the like using a conductor housing 14. The conductor housing 14 may comprise various types of conductor housings 14 such as, but not limited to, a mineral insulated (MI) cable or ceramic insulator. For example, a MI cable 14 may comprise one or more wires disposed within a sheath 26 (e.g., a metal sheath) which are configured to electrically couple the sensor 12 to the wiring harness 16. The sheath 26 may provide mechanical strength and/or protection to the MI cable 14 and may also position the temperature sensor 12 and/or wiring harness 16 to prevent contact with other components. The mineral insulation may provide the necessary thermal resistance for the sensor system 10 to withstand the high temperatures experienced within an exhaust system 13. The MI cable 14 may, however, be particular sensitive to moisture absorption. For example, humidity in the ambient air may cause a dielectric failure if the air has access within the MI cable 14. As discussed herein, the sensor system 10 may include a coupler 18 configured to reduce or eliminate water absorption of the MI cable 14, particularly from water being absorbed into the MI cable 14 from the end of the MI cable 14 connected to the wiring harness 16.
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The grommet 28 may include a high temperature elastomer material. The elastomer material may include a resiliently deformable material configured to form a seal as described herein and may be configured to be partially compressed by the harness sleeve 32. For example, the grommet 28 may include a high temperature fluorocarbon rubber. The fluorocarbon rubber may be configured to withstand temperatures of up to 536 degrees F.
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Once the grommet 28 and nugget 30 are received within the cavity 52 of the harness sleeve 32, the harness sleeve 32 may be crimped to form a mechanical connection. For example, the harness sleeve 32 may be crimped about a portion overlaying the grommet 28 to form a first crimp 56 which may compress the elastomer material of the grommet 28. In the non-compressed state, the passageway 36 of the grommet 28 may be configured to readily received the harness wire 16 and/or wires 34a, 34b and may have an outer size and/or shape configured to be readily received in the cavity 52 of the harness sleeve 32 to facilitate assembly of the sensor system 10. The first crimp 56 between the harness sleeve 32 and the grommet 28 may compress the elastomer material of the grommet 28 thereby substantially eliminating any clearance provided between the grommet 28 and the wires 34a, 34b of the wire harness assembly 16 and forming a seal between the grommet 28 and the wire harness assembly 16. The first crimp 56 may also substantially eliminate any clearance provided between the grommet 28 and the harness sleeve 32 thereby forming a seal.
The harness sleeve 32 may also be crimped about a portion overlaying the nugget 30 to form a second crimp 58. The second crimp 58 between the harness sleeve 32 and the nugget 30 may generally secure the nugget 30 to the harness sleeve 32 and, along with the bonding of the terminals 48a, 48b to the nugget 30, may provide strain relief for the wire harness 16. According to at least one embodiment, the second crimp 58 may be located about the radial groove 44 in the nugget 30 and may also facilitate alignment of the nugget 30 with respect to harness sleeve 32.
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While the wiring harness 16 has been illustrated having two wires 34a, 34b, it should be appreciated that wiring harness 16 may have fewer than or greater than two wires 34a, 34b. For example, the wiring harness 16 may include one wire, three wires, four wires or the like. The grommet 28 and/or the nugget 30 may therefore be configured to receive greater than or fewer than two wires 34a, 34b. Similarly, the conductor housing 14 may have fewer than or greater than two wires and/or terminals.
Accordingly, consistent with at least one embodiment herein, a sensor system may comprise a sensor coupled to a conductor housing, a wire harness assembly, and a coupler configured to couple the conductor housing to the wire harness assembly. The coupler may include a grommet, a nugget, and a harness sleeve. The grommet may include a high temperature seal between the wires of the wiring harness and the harness sleeve. Crimping the grommet into the harness sleeve compresses the elastomer eliminating the clearance provided for easy assembly thus achieving a seal. The nugget may be over-molded to the terminals of the wire harness and may be configured to provide the proper orientation and spacing of the wire terminals. A wide shallow groove may be molded around the outside of the nugget to provide a mechanism of attaching the nugget to the harness sleeve. The mechanical crimping of the nugget in the harness sleeve and the bonding of the terminals inside the nugget may provide strain relief for the wire harness. The high temperature materials allow the sensor junction to be shorter and closer to the heat source. Attaching the wire harness to the conductor housing may be done by resistance welding wire terminals to the conductors of the conductor housing. The wire harness may be capable of withstanding pull force without breaking weld joints between the wire terminals and the conductors within the conductor housing and may provide robust strain relief for the wire harness. The material selection and combination may permit a higher continuous use temperature due to thermal conduction, convection and radiation.
According to at least one embodiment consistent herein, the present disclosure may include a sensor system comprising a wiring harness comprising at least one wire, a grommet comprising at least one passageway configured to receive the at least one wire, a nugget comprising at least one terminal molded into the nugget, a sensor; a conductor housing coupled to the sensor and to the at least one terminal; and a harness sleeve defining at least one cavity configured to receive the nugget and at least a portion of the grommet, wherein the harness sleeve includes a first crimp coupling the harness sleeve to the grommet to form a seal.
According to yet another aspect, the present disclosure may feature a system comprising a housing and a sensor system. The sensor system may comprise a sensor configured to be coupled to the housing; a wiring harness comprising at least one wire; a grommet comprising at least one passageway configured to receive the at least one wire; a nugget comprising at least one terminal molded into the nugget, the at least one terminal coupled to the at least one wire; a conductor housing coupled to the temperature sensor and to the at least one terminal; and a harness sleeve defining at least one cavity configured to receive the nugget and at least a portion of the grommet, wherein the harness sleeve is coupled to the conductor housing and includes a first crimp coupling the harness sleeve to the grommet.
In yet a further aspect, the present disclosure may feature a sensor system comprising a sensor coupled to a conductor housing; a wire harness assembly; and a coupler configured to couple the conductor housing to the wire harness assembly. The coupler may comprise a nugget over-molded to the terminals of the wire harness to provide an orientation and spacing of the wire terminals. The nugget may further comprise a wide shallow radial groove about the outside of the nugget. The coupler may also include a grommet comprising an elastomeric material and a harness sleeve coupled to the conductor housing. The harness sleeve may comprise a cavity to receive the nugget and at least a portion of the grommet; a first crimp compressing the elastomer material of the grommet to form a seal between the wires of the wiring harness and the harness sleeve; and a second crimp aligned with the radial groove in the nugget, the second crimp securing the harness sleeve to the nugget, wherein the second crimp and the overmolding of the terminals inside the nugget provide strain relief for the wire harness.
In an addition aspect, the present disclosure may feature a method of assembling a sensor system. The method may comprise advancing at least one wire of a wiring harness through at least one passageway of a grommet, the at least one wire having a at least one terminal coupled to a distal end; molding a nugget over a portion of the at least one terminal; coupling a conductor of a conductor housing to the at least one terminal; coupling the conductor housing to a harness sleeve and to a sensor; receiving the nugget and at least a portion of the grommet within a cavity of the harness sleeve; and coupling the harness sleeve to the grommet for form a seal.
The present disclosure has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. The features and aspects described with reference to particular embodiments disclosed herein may be susceptible to combination and/or application in various other embodiments described herein. Such combinations and/or applications of such described features and aspects to such other embodiments are contemplated herein. Additionally, the embodiments disclosed herein are susceptible to numerous variations and modifications without materially departing from the spirit of the disclosed subject matter. Accordingly, the present disclosure herein should not be considered to be limited to the particular embodiments disclosed herein.
The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/159,955, filed Mar. 13, 2009 and entitled EXHAUST GAS TEMPERATURE SENSOR LEAD SEALING AND STRAIN RELIEF, which is fully incorporated herein by reference.
Number | Date | Country | |
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61159955 | Mar 2009 | US |