JPS59131116A - Air blower - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention is applicable to relatively low wind pressure (1
The present invention relates to a blower with an additional function of measuring, displaying, and outputting the operating air volume as a signal when the blower (0 to 160 wAq) is operated in various duct pipes.

[Prior art]

In the case of general fluid machinery such as pumps and compressors, the operating flow rate flowing through the piping is determined by the characteristics of the fluid machinery and the resistance characteristics of the piping, and is usually measured by inserting a flow meter in the middle of the piping. .

However, in the case of general blowers used for building air conditioning, etc. (1) The pressure inside the piping is close to atmospheric pressure (10 to 160w
AQ), air with a small specific weight (1/1000 of water) flows, and its wind speed is small (3 to IQm/s), so the flow is not stabilized and the wind speed distribution inside the pipe is constantly changing. .

(2) The air volume values that have been put into practical use range from small air volumes to large air volumes (10 to 5000 m3/rIuJt), and there are pipes (i.e. ducts) ranging from small to large.

(3) The shape of ducts is not standardized like water pipes, and ducts of various shapes exist.

Moreover, due to the way it is used, the duct piping has many curved and branched cross-sectional changes, and the length of the straight part of the dust is small compared to the duct diameter.

Because of the above (1) to (3), it can be used as a measuring device for the internal dust flow rate of a blower, for any size duct, any shape, and any piping condition.
There is no readily available, inexpensive, and standardized measuring device available.

Therefore, it is difficult to measure the operating flow rate by inserting a flow meter into the piping as in general fluid machines. Therefore, in the past, the flow rate in the duct of a building air conditioning blower had to be measured by measuring the current value of the model of the blower installed on site, and based on this measurement value, it was calculated using the blower's performance curve. Estimate the air flow rate in the duct from the air flow rate, or
Alternatively, the current method is to use a hot-wire anemometer to measure the wind speed at each position in the wind pipe, and then integrate and calculate the air flow rate in the duct from the measured values.

However, such a method requires a great deal of labor and time, and it is impossible to constantly detect the air flow rate in the duct and perform operational management, or to control the operation of the air conditioning system using this information.

[Purpose of the invention]

In the case of a blower, the piping is complicated and it is difficult to commercialize a flowmeter that can be used practically for all piping. The idea is to add a function to the blower itself that can constantly measure and display the operating air volume, and output it as a signal. The purpose is to provide the following.

[Summary of the invention]

The present invention focuses on the fact that the flow in the suction pipe and its wind speed distribution are stable due to the bellmouth rectification action of the suction pipe of the blower and the suction action of the impeller. The unique feature is that a small flow rate detection device such as a hot wire resistor that can output a small flow rate is installed in the middle of the path to detect the bypass flow rate and measure the operating air volume of the blower. .

Embodiment FIG. 1 shows a diagram of the principle of the present invention, where l is a casing, 2 is a blower, and 3 is a suction pipe. The bypass flow path is installed in the range S in the figure, that is, in the range L/D≧1. (
A), (B), and (C) show the wind speed distribution at each point, and the above S
Within the range of , this distribution is relatively stable.

FIG. 2 shows an embodiment of the invention. In the figure, reference numeral 20 denotes a bypass air passage, in which a typical hot wire type resistor 23 is housed as a microflow detection means. Reference numeral 21 denotes a static pressure pipe whose one end communicates with the bypass air passage 20, and the other end 24 passes through a bracket 26 and is opened in a direction perpendicular to the air blowing direction of the suction pipe 3 (non-air blowing direction). 22 is a general pressure pipe whose one end communicates with the bypass air passage 20, and whose other end passes through the bracket and connects to the suction pipe 3 through the opening 25.
It is opened in the direction of air flow. In this case, one or more openings 25 are provided in the suction pipe in a direction facing the flow, depending on the size of the suction pipe.

Further, an enlargement means 27 is provided in the total pressure pipe 22 so that its dimension can be extended.

Furthermore, a bypass air passage 20. Static pressure tube 21. A bypass flow path control means 2 is provided in either of the total pressure pipes 22, the ventilation area of which is much smaller than the other ventilation path areas, and capable of regulating the bypass air volume and adjusting and controlling the bypass flow rate.
8 will be provided. Further, a bridge circuit output signal control means 30 is connected to the hot wire type resistor 23 and built in the box 29 to enable adjustment of its output signal.

In addition, the hot wire resistor 23 is connected to a bridge circuit,
Each of the circuits is provided integrally with a box 29 containing the circuit so as to be removable from the bypass air passage 20.

Further, the bridge circuit output signal control means described above is provided separately from the bridge circuit due to the need to easily adjust the output signal.

Further, in the present invention, the measured value of the flow rate is transmitted to the bypass flow path control means 2.
8 or both with the bridge circuit output signal control means 30, the structure is such that initial adjustment can be made at the start of operation to correct the measured value, and even if it is installed and used in various piping, there will be no error. It can be used with less and more precision.

Furthermore, the present invention has a configuration in which the hot wire type resistor 23 and the bridge circuit are integrated and can be removed from the bypass air path 20, and high precision is required and the expensive hot wire type resistor and bridge circuit are combined. It is possible to construct a flow meter side device that can be installed in ducts of various sizes with one type of length, and it is possible to provide an inexpensive flow rate measuring device that is standardized for various duct piping.

3 and 4 show other embodiments of the present invention. In the figure, a total pressure pipe 22 is provided inside the static pressure pipe,
A static pressure pipe ventilation path is configured between the static pressure pipe and the total pressure pipe. A seven flange 36 is attached to one end of the total pressure pipe 22, and is attached with a bolt using a fitting 37 provided thereon so as to communicate with the bypass air passage.

The other end of the static pressure pipe 21 is opened in a direction perpendicular to the air blowing direction of the suction pipe 3 . This static pressure pipe 21 is peered into a metal fitting 32 attached to the suction pipe 3 via a nut 33. At this time, a ring-shaped fitting 35 made of rubber or the like is provided between the static pressure pipe 21 and the metal fitting, and the metal fitting 32 attached to the suction pipe and the static pressure pipe 21 form a binox air path. It is integrated like this. In this case, the opening 25 of the total pressure pipe 22 can be easily aligned to face the flow of the duct 1 and is configured to be fixed.

Further, the total pressure pipe 22 is removably connected via a nut 33 near the suction pipe, as shown in detail in FIG.

In the present invention, a bridge circuit connected to a hot wire type resistor 23 built in the bypass air flow path is built in the box 29. FIG. 6 shows an example of a typical bridge circuit. In FIG. 6, a Wheatstone bridge is constructed with the hot wire resistor 13, that is, the flow rate measuring resistor 73a and the temperature compensation resistor 73b, and the resistors 71, 72°Q1 73, and the potential difference at the midpoint is measured using an operational amplifier 70. It is detected by a differential amplifier circuit. This signal is input to the pace of the transistor 74, and closed-loop control is performed so that the potential at the midpoint of the bridge is always equal. According to the bridge equilibrium condition, the resistance R1 of the flow rate measuring resistor 73a is expressed by the following equation.

However, R is the resistance value of the resistor 71, R is the resistance value of the resistor 72, R3 is the resistance value of the resistor 73, and R is the resistance value of the temperature compensation resistor 73b. In reality, a>Rt, the flow rate measuring resistor 73a is in a heated state, and the temperature compensating resistor 73b is slightly heated, but almost equal to the atmospheric temperature. Therefore, when the air temperature rises, the resistance of Rt also increases accordingly, compensating for the influence of the rise in air temperature. Also, if the air temperature is constant, R1 is constant and %RW is the air flow rate (lO
) so that it is a constant value regardless of the operational amplifier 74.
is activated to control the current flowing through the bridge.

That is, the air flow rate flowing through the bypass air path 20 can be determined by the potential at the midpoint of this bridge or the potential at the emitter of the transistor 74;
The air flow rate is required.

Letting the output signal of this bridge circuit be Vt, the following relationship exists between it and the air flow rate q passing through the bypass air passage 20.

V I= Ct +Cz y'1-(2) In addition, c, j
c is a constant related to the hot wire resistor.

As the minute stagnation amount detection means of the present invention, an electromagnetic flow meter, an ultrasonic flow meter, or a thin flow needle may be used.

FIGS. 7 and 8 show examples in which the shape and dimensions of the suction pipe of the blower are different. The suction pipe is configured to extend beyond the casing l to the outside part. In this case, as shown in Figure 1, the L dimension is L≦D (11) because the bellmouth rectification effect of the suction pipe and the suction force of the impeller affect the flow in the suction pipe on the wind speed distribution. .

In the case of the present invention, the bypass air passage is provided outside the casing l. In the example of Figure 8, in addition,
Contains a straight pipe section within the suction pipe.

The above examples apply not only to multi-blade fans and turbo fans, but also to mixed flow fans and axial fans.

FIG. 9 shows an embodiment in which the present invention is applied to a mixed flow fan. FIG. 10 shows an embodiment in which the present invention is applied to an axial fan. The present invention also includes a configuration in which the length of the total pressure pipe 22 does not extend over the entire cross section of the suction pipe, but extends halfway there.

〔Effect of the invention〕

According to the present invention, the blower is operated by a slight bypass flow rate in the suction pipe of the blower, which has a stable flow and wind speed distribution in addition to the bellmouth rectification action of the blower suction pipe and the suction force action of the impeller. This method measures the air volume, allowing accurate measurement even when the blower is used in a variety of pipes.

[Brief explanation of drawings]

(12) Fig. 1 is a diagram for explaining the operating principle of the present invention, Fig. 2 is a vertical cross-sectional view of main parts showing an embodiment of the present invention, Figs.
The figure is a longitudinal sectional view of a main part of another embodiment of the present invention. FIG. 5 is a vertical cross-sectional view of a main part showing an example of a total pressure pipe according to the present invention, FIG. 6 is a diagram showing an example of a bridge circuit for flow rate detection, and FIGS. It is a figure which shows an example. 3... Suction pipe, 20... Bypass air path, 21...
・Static pressure pipe. (13) Figure 1 Figure 2 Figure 3 Figure 5 Figure 24 Kuzu 7 Figure Z 6 Figure/jb Tomi 9 Figure 3

Claims (1)

[Claims] 1. In a blower consisting of an impeller, a casing, and a suction pipe, a bypass air passage is provided in the suction pipe, a microflow detection means is installed therein, and a static pressure pipe and a total pressure pipe are provided at both ends of the bypass air passage. A blower characterized in that the other ends of the static pressure pipe and the total pressure pipe are opened in the non-blowing direction and the blowing direction of the suction pipe, respectively. Windage. 3. Provide bypass flow rate control means that can regulate the bypass air flow rate and adjust the pie and bus flow rates;
In addition, the total pressure pipe is provided with an enlargement means that can extend its length, and the output signal control means configured to be able to adjust the electrical output signal of 4 and the trace amount detection means in the suction pipe is provided as pie 5 of item 3, The hot wire type resistor as the micro-flow ball emitting means and the bridge circuit are integrated, and the bar 6, the output signal 7 connected to the bridge circuit, and the suction pipe are connected to the outside of the casing. Its extended length is the maximum diameter length inside the casing.