Provided is a thermal flow meter that can be prevented from being eroded due to adhesion of water or like to a cut end portion of the lead exposed from the mold resin of the circuit package. A thermal flow meter 300 of the present invention is a thermal flow meter having a circuit package 400 formed by mounting a detection element 518 on leads 544 and 545 supported by a support frame 512, sealing with a mold resin, and cutting off the support frame 512, wherein cut end portions 544a and 545a of the leads 544 and 545 exposed from the mold resin of the circuit package 400 by cutting off the support frame 512 is covered by a covering portion 371.

A collar is provided for use with a fluid flow sensor to reduce condensation of a moist gas flowing through the fluid flow sensor. The collar comprises a body defining an interior that defines an airspace between the collar and the housing of the fluid flow sensor when the collar is positioned on the fluid flow sensor. The collar also includes a heat source secured to the body and adapted to heat air contained within the airspace to consequently heat the housing of the fluid flow sensor and the interior surfaces of the sensor to reduce condensation of the moist gas.

A collar is provided for use with a fluid flow sensor to reduce condensation of a moist gas flowing through the fluid flow sensor. The collar comprises a body defining an interior that defines an airspace between the collar and the housing of the fluid flow sensor when the collar is positioned on the fluid flow sensor. The collar also includes a heat source secured to the body and adapted to heat air contained within the airspace to consequently heat the housing of the fluid flow sensor and the interior surfaces of the sensor to reduce condensation of the moist gas.

The present invention provides a thermal flow meter 300 which reduces a stress applied from a fixing portion 3721, which is used to hold and fix a circuit package 400 with respect to a housing 302, to the circuit package 400 and has high reliability. In the thermal flow meter of the invention, the circuit package 400 embedded with a flow rate measurement circuit is formed through a first resin molding process, the fixing portion 3721 is formed along with the housing 302 through a second resin molding process, and the circuit package 400 is enveloped by the fixing portion 3721, whereby the circuit package 400 is held by and fixed to the housing 302. In order to reduce the influence of a stress, generated based on a temperature change of the fixing portion 3721, on the circuit package 400, the fixing portion 3721 is constituted of a thick portion 4714 and a thin portion 4710. Since thickness of a resin of the thin portion 4710 is small, the stress to be generated is small, and a force applied to the circuit package 400 can be reduced.

The present invention provides a thermal flow meter 300 which reduces a stress applied from a fixing portion 3721, which is used to hold and fix a circuit package 400 with respect to a housing 302, to the circuit package 400 and has high reliability. In the thermal flow meter of the invention, the circuit package 400 embedded with a flow rate measurement circuit is formed through a first resin molding process, the fixing portion 3721 is formed along with the housing 302 through a second resin molding process, and the circuit package 400 is enveloped by the fixing portion 3721, whereby the circuit package 400 is held by and fixed to the housing 302. In order to reduce the influence of a stress, generated based on a temperature change of the fixing portion 3721, on the circuit package 400, the fixing portion 3721 is constituted of a thick portion 4714 and a thin portion 4710. Since thickness of a resin of the thin portion 4710 is small, the stress to be generated is small, and a force applied to the circuit package 400 can be reduced.

An air flow measuring device is adapted to be attached to a duct. The device includes a first housing, a second housing, and a flow sensor. The first housing defines a bypass flow passage which takes in a part of air flowing in the duct, and includes a hollow part and a recess. The bypass flow passage is formed in the hollow part. The recess is formed on an upper side of the hollow part in a vertical direction of the device, and at the recess, an outer surface of the first housing is recessed inward of the first housing. The second housing is formed through secondary formation with the first housing as a primary formed part. The first housing is held on a lower side of the second housing in the vertical direction. The flow sensor is disposed in the bypass flow passage.

An air flow measuring device is adapted to be attached to a duct. The device includes a first housing, a second housing, and a flow sensor. The first housing defines a bypass flow passage which takes in a part of air flowing in the duct, and includes a hollow part and a recess. The bypass flow passage is formed in the hollow part. The recess is formed on an upper side of the hollow part in a vertical direction of the device, and at the recess, an outer surface of the first housing is recessed inward of the first housing. The second housing is formed through secondary formation with the first housing as a primary formed part. The first housing is held on a lower side of the second housing in the vertical direction. The flow sensor is disposed in the bypass flow passage.

Provided is a thermal flow meter to improve the measurement accuracy of a temperature detector provided in a thermal flow meter is a thermal flow meter to improve the measurement accuracy of a temperature detector provided in a thermal flow meter. The thermal flow meter includes a bypass passage through which a measurement target gas 30 flowing through a main passage flows, and a circuit package 400 which includes a measurement circuit for measuring a flow rate of the measurement target gas 30 flowing through the bypass passage and a temperature detecting portion 452 for detecting a temperature of the measurement target gas. The circuit package 400 includes a circuit package body which is molded by a resin to internally envelope the measurement circuit and a protrusion 424 molded by the resin. The temperature detecting portion 452 is provided in the leading end portion of the protrusion 424, and at least the leading end portion of the protrusion protrudes to the outside from a housing 302.

Provided is a thermal flow meter to improve the measurement accuracy of a temperature detector provided in a thermal flow meter is a thermal flow meter to improve the measurement accuracy of a temperature detector provided in a thermal flow meter. The thermal flow meter includes a bypass passage through which a measurement target gas 30 flowing through a main passage flows, and a circuit package 400 which includes a measurement circuit for measuring a flow rate of the measurement target gas 30 flowing through the bypass passage and a temperature detecting portion 452 for detecting a temperature of the measurement target gas. The circuit package 400 includes a circuit package body which is molded by a resin to internally envelope the measurement circuit and a protrusion 424 molded by the resin. The temperature detecting portion 452 is provided in the leading end portion of the protrusion 424, and at least the leading end portion of the protrusion protrudes to the outside from a housing 302.

Provided is a thermal flow meter that can be prevented from being eroded due to adhesion of water or like to a cut end portion of the lead exposed from the mold resin of the circuit package. A thermal flow meter 300 of the present invention is a thermal flow meter having a circuit package 400 formed by mounting a detection element 518 on leads 544 and 545 supported by a support frame 512, sealing with a mold resin, and cutting off the support frame 512, wherein cut end portions 544a and 545a of the leads 544 and 545 exposed from the mold resin of the circuit package 400 by cutting off the support frame 512 is covered by a covering portion 371.