JPH0664119U - Thermal mass flow measurement device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a thermal mass flow measuring device capable of performing accurate mass flow measurement even when the ambient temperature fluctuates drastically. [Structure] Bypass pipe 12 'is connected to outer pipe 12a and inner pipe 1
2b, and the partial fluid f'is
2b, the measurement fluid f1 and the non-measurement fluid f2 flowing between the outer pipe 12a and the inner pipe 12b are diverted, and heating by the heater HT and thermistors TH1 and TH are performed.
The temperature detection by 2 is performed on the measurement fluid f1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a thermal mass flow rate measuring device suitable for use in a hydraulic or pneumatic system of an aircraft or the like.

[0002]

[Prior art]

 Conventionally, various devices have been developed for measuring the mass flow rate of a fluid flowing in a pipe in a hydraulic or pneumatic system of an aircraft or the like. As this type of device, for example, a thermal mass flow measuring device shown in FIG. 2 is known. In the figure, the fluid f flowing in the main pipe 10 is divided into the bypass pipe 12 via the fluid throttle 11 such as an orifice and is sent to the sensor section S. In the sensor section S, two thermistors TH1 and TH2 are provided in the bypass pipe 12 at a predetermined distance. A heater HT for heating the fluid is provided between the thermistors TH1 and TH2.

With such a configuration, the temperature of the fluid f ′ split from the main pipe 10 to the bypass pipe 12 before and after being heated by the heater HT is detected by the thermistors TH1 and TH2, respectively. Then, the mass flow rate of the fluid f ′ flowing in the bypass pipe 12 is calculated from the temperature difference before and after heating by an operation based on the thermodynamic principle. In this way, the mass flow rate of the fluid f flowing in the main pipe 10 can be measured based on the cross-sectional dimension ratio of the main pipe 10 and the bypass pipe 12 and the like.

[0004]

[Problems to be solved by the device]

 By the way, as described above, in the conventional thermal mass flow rate measuring device, the mass flow rate is measured based on the temperature difference of the fluid f ′ before and after heating. However, if the temperature around the bypass tube 12 fluctuates significantly, the temperature difference of the fluid f ′ detected by the thermistors TH1 and TH2 is affected by other than heating by the heater HT, and an error occurs in the mass flow rate measurement. There was a problem that it would end up.

The present invention has been made under such a background, and provides a thermal mass flow measuring device capable of performing accurate mass flow measurement even when the ambient temperature fluctuates drastically. The purpose is to do.

[0006]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, the present invention aims at solving the above-mentioned problems by dividing a part of a fluid flowing in a main pipe into a bypass pipe, heating means for heating a partial fluid flowing in the bypass pipe, and Based on a first temperature detecting means for detecting a temperature before heating, a second temperature detecting means for detecting a temperature of the partial fluid after heating, and a temperature detected by the first and second temperature detecting means. A thermal mass flow rate measuring device comprising a measuring means for measuring a mass flow rate of a fluid flowing in the main pipe, wherein the bypass pipe has a double structure consisting of an inner pipe and an outer pipe, and the partial fluid is The flow is divided into a measuring fluid flowing in the inner pipe and a non-measuring fluid flowing between the outer pipe and the inner pipe, and the heating by the heating means and the first and second temperature detecting means are performed. Yo The temperature detection is performed on the measurement fluid.

[0007]

[Action]

 According to this invention, the measuring fluid flowing in the inner pipe is separated from the outside of the bypass pipe by the non-measuring fluid flowing around the inner pipe, and the temperatures before and after the heating of the measuring fluid by the heating means are the first and the second. The mass flow rate of the fluid flowing in the main pipe is measured based on the temperature difference before and after the heating, which is detected by the second temperature detecting means.

[0008]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a thermal mass flow rate measuring device according to an embodiment of the present invention. In this figure, the same parts as those shown in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 1, the bypass pipe 12 ′ has a double structure composed of an outer pipe 12 a and an inner pipe 12 b, and a fluid f ′ diverted to the bypass pipe 12 ′ is included in the inner pipe 12 b. A fluid restrictor (orifice or the like) 13 is provided for further diversion. Further, the two thermistors TH1 and TH2 are provided at a predetermined distance inside the inner tube 12b, and the heater HT is installed between these thermistors TH1 and TH2.

According to this structure, the fluid f ′ split from the main pipe 10 into the bypass pipe 12 ′ is further divided into the measurement fluid f1 flowing in the inner pipe 12b, the outer pipe 12a and the inner pipe 12b. And the non-measurement fluid f2 flowing between The temperature of the measurement fluid f1 before and after being heated by the heater HT is detected by the thermistors TH1 and TH2, respectively, and the calculation is performed based on the temperature difference, so that the mass flow rate of the fluid f flowing in the main pipe 10 is increased. Is measured.

At this time, since the measuring fluid f1 is separated from the outside of the bypass pipe 12 'by the non-measuring fluid f2 flowing around the inner pipe 12b, the temperature difference detected by the thermistors TH1 and TH2 is small. , It is not affected by the temperature change around the bypass pipe 12 '. As a result, a measurement error caused by a temperature change around the bypass pipe 12 'is eliminated, so that accurate mass flow rate measurement can be performed.

[0012]

[Effect of device]

 As described above, according to the present invention, the measuring fluid flowing in the inner pipe is separated from the outside of the bypass pipe by the non-measuring fluid flowing around the inner pipe, and before and after the heating of the measuring fluid by the heating means. The temperature is detected by the first and second temperature detecting means, and the mass flow rate of the fluid flowing in the main pipe is measured based on the temperature difference before and after heating. Since the change in ambient temperature does not affect the temperature, accurate mass flow rate measurement can be performed even when the ambient temperature fluctuates drastically.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a thermal mass flow rate measuring device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional thermal mass flow rate measuring device.

[Explanation of symbols]

 10 Main pipe 11,13 Fluid throttle 12,12 'Bypass pipe 12a External pipe 12b Internal pipe

Claims (1)

[Scope of utility model registration request] 1. A flow dividing means for dividing a part of a fluid flowing in a main pipe into a bypass pipe, a heating means for heating a partial fluid flowing in the bypass pipe, and a first means for detecting a temperature of the partial fluid before heating. Based on the temperature detected by the temperature detecting means, the second temperature detecting means for detecting the temperature of the partial fluid after heating, and the temperature detected by the first and second temperature detecting means. In the thermal mass flow rate measuring device, the bypass pipe has a double structure including an inner pipe and an outer pipe, and the partial fluid is a measuring fluid flowing in the inner pipe and the measuring fluid. The non-measuring fluid flowing between the outer pipe and the inner pipe is branched, and heating by the heating means is performed,
A thermal mass flow rate measuring device, wherein temperature detection by the second temperature detecting means is performed on the measurement fluid.