JPH0484716A - Flow-rate detecting apparatus - Google Patents

Abstract

PURPOSE:To make it possible to detect the accurate flow rate by correcting the error cuased by the temperature of fluid based on the signal from a number-of-rotation detector and the signal from a temperature detector. CONSTITUTION:When fluid flows in the direction of arrows, the turning stream is generated with fixed wings having an angle with respect to the flowing direction. When a magnetic ball 7 is brought into contact with the position of a two-dot chain line C, i.e. a supporting frame 2 and a cap 6 and turned by the turning stream, the number of periodic waveforms in output of the magnetoresistance element of a number-of-ortation detector 8 is changed in a specified time T based on the high and low values of the number of rotation. A detecting device 8 converts the periodic waveforms into pulses. A temperature detector 9 detects the temperature of the fluid at the inlet port side of a flow path. Then, the signal of the pulse number and the signal from the temperature detector 9 are inputted into an operating means 10. In the operating means 10, the corrected value of the temperature is obtained with a computing expression which is stored beforehand. The pulse number is multiplied by the corrected value, and the pulse number after the correction is obtained. Furthermore, the flow rate corresponding to the pulse number which is corrected based on the temperature is obtained by the expression of relation between the pulse number and the flow rate at a reference fluid temperature which is stored beforhand in the operating means 10.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a flow rate detection device used for controlling the amount of hot water in water heating equipment.

BACKGROUND OF THE INVENTION Conventionally, this type of flow rate detection device, as shown in FIG.
A support frame 2 is press-fitted into the inside of a body 1 connected to a fluid passage, and a guide 3 is provided at the center of the support frame 2. This guide 3
and the support frame 2 are connected by a plurality of fixed blades 4 as shown in FIGS. 5A and 5S, and the fixed blades 4 are twisted to form an angle in the flow direction.

A magnetic ball 7 is movably housed between the fixed blade 4, the support frame 2, and a lid 6 having a fluid passage hole 5. A rotation speed detection device 8 having a circuit including a magnetoresistive element and a permanent magnet is arranged on the outer circumference of the body 1 where the magnetic ball 7 is located.

As shown by the solid line and the two-dot chain line B, the magnetic ball 7 does not fall out from between the guide 3, the fixed blade 4, the lid 6, and the support frame 2, and also maintains the angle of the fixed blade 4 in the flow direction. , and rotates along the inner periphery of the support frame 2 while contacting the lid 6 as shown by the two-dot chain line C. This rotational speed is proportional to the flow rate, and the rotational speed detection device 8 detects the number of periodic waveforms in a predetermined time and converts this into a pulse signal to detect the flow rate.

Problems to be Solved by the Invention However, in the above configuration, in order to control a constant temperature in a water heater, for example, a means is selected that changes the amount of fuel supplied in response to the water volume signal, and the water volume signal changes depending on the water temperature. Feedback control was then performed to correct the amount of water, and it took a long time for the water temperature to stabilize. In addition, when a fixed amount of hot water is supplied to a bathtub or the like for quantitative counting, there are problems such as a delay in the amount of hot water supplied to the bathtub due to seasonal changes in water temperature.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to detect an accurate flow rate by correcting errors caused by fluid temperature.

Means for Solving the Problems In order to achieve the above object, the present invention converts the rotational speed of a sphere having a magnetic body into a pulse signal, and calculates the pulse signal and the signal of a temperature detector that detects the fluid temperature. It was designed to be received at

Effect: With the above means, the present invention allows the calculating means to temperature-correct the pulse signal, calculate the flow rate of the fluid based on the temperature-corrected pulse signal, and measure the temperature-corrected flow rate.

Embodiments Hereinafter, embodiments of the flow rate detection device of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which a support frame 2 is press-fitted into a body 1, and a guide 3 at the center of the support frame 2 is connected to a plurality of fixed blades 4 provided at angles in the flow direction. It is supported as shown in FIG. 1a, taken along the A-A cross section of FIG. There is. On the outer periphery of the body 1 where the magnetic ball 7 is located, a rotation speed detection device 8 having a circuit including a magnetoresistive element and a permanent magnet is arranged. Further, the body 1 is provided with a temperature sensor 9 in a fluid-tight manner on the inlet side of the flow path to detect the fluid temperature. Signals from the temperature detector 9 and the rotational speed detecting device 8 are sent to an arithmetic means 10 which stores in advance temperature correction values for the fluid temperature and flow rate, and relational expressions between the number of pulses and the flow rate.

In the above embodiment, as shown by the arrow in the figure, when the fluid flows, the flow becomes a swirling flow due to the fixed jg4 having an angle in the flow direction. When the magnetic ball 7 rotates at the position indicated by the two-dot chain line C in the figure due to this swirling flow, that is, in contact with the support frame 2 and the lid 6, the output of the magnetoresistive element of the rotation speed detection device 8 will change when the rotation speed is low. As shown in FIG. 2(a), as the rotational speed increases, the number of periodic waveforms within a certain period of time T changes as shown in FIG. 2(c). Further, the rotation speed detection device 8 converts this periodic waveform into pulses, which is shown in the second (b) and (d). FIG. 2(b) is a pulse-converted version of FIG. 2(a). FIG. 2(d) is a pulse-converted version of FIG. 2(c).

FIG. 3 is a graph showing the relationship between the number of pulses stored in advance in the calculation means 10 of a certain fluid and the flow rate, and the relationship between the number of pulses and the flow rate is directly proportional. Therefore, by measuring the number of pulses within the predetermined time T, the flow rate can be determined. In the figure, three straight lines are drawn as an example. It shows the relationship between the flow rate and the number of pulses at t, or fluid temperature, where L is t, a lower fluid temperature, and 1° is 1. A straight line showing the relationship between flow rate and number of pulses at higher fluid temperatures. In other words, even if the flow rate is the same, if the temperature of the fluid changes, the viscosity of the fluid changes, and even if the flow rate is the same, the number of rotations of the magnetic ball 7 differs, and the number of pulses changes.

FIG. 4 shows the relationship between the fluid temperature of the fluid shown in FIG. 3 and the temperature correction value. This temperature correction value can be determined as follows. Now, each fluid temperature t at a certain flow rate ■ shown in FIG.

The number of pulses for a certain period of time T in Le and tz is 8.
If it is 10.12, then it is the fluid temperature. The temperature correction value at this time is set to 1 with reference to . Therefore, the liquid temperature 1. The temperature correction value of is 10/8-1.25 as a ratio of the fluid temperature t to the number of pulses 10. Similarly, the temperature correction value of the fluid temperature t8 is 10/1240.833. If you put these numbers in the diagram and connect them with a line, the W line will be drawn.

Next, a method for temperature correction of flow rate will be explained.

First, the rotation speed detection device 8 detects, for example, the fluid temperature t1.
A signal with a pulse number of 8 at , and a signal of the fluid temperature t detected by the temperature detector 9 enter the calculation means 10 . Then, the calculation means 10 obtains a temperature correction value of 1.25 from a previously stored calculation formula corresponding to the W line shown in FIG. 4, and multiplies it by the number of pulses 8 to obtain a corrected number of pulses 10. Furthermore, the calculating means 10 calculates the flow rate corresponding to the temperature-corrected number of pulses from the relational expression between the number of pulses and the flow rate at the reference fluid temperature L0 stored in advance, and outputs this signal.

Effects of the Invention As is clear from the above description, the present invention calculates a fluid temperature detection signal by a temperature sensor and a pulse signal based on the rotation of a ball having a magnetic body using a calculation means, and changes the fluid temperature. Detects accurate flow rate by correcting detection errors caused by
It is possible to shorten the temperature control time of hot water supply equipment and eliminate seasonal fluctuations in the fixed supply of bath water.

[Brief explanation of drawings]

FIG. 1a shows an embodiment of the flow rate detection device of the present invention, and the 11th
1 is a longitudinal sectional view of the same; FIGS. 2 a to d are waveform diagrams of the rotational speed detection device according to the same embodiment and waveform diagrams thereof after f conversion; FIG. 3 is a characteristic diagram showing the relationship between the flow rate and the number of pulses in the same embodiment, FIG. 4 is a characteristic diagram showing the relationship between the fluid temperature and the temperature correction value in the same embodiment, and FIG. 5a shows a conventional flow rate detection device. FIG. 5 is a sectional view taken along line A-A in FIG. 5, and FIG. 5 is a longitudinal sectional view thereof. 4...Fixed wing, 7...Magnetic ball, 8
... Rotation speed detection device, 9 ... Temperature detector, 10 ... Calculation means. Name of agent Patent attorney Shigetaka Awano (1 person) Figure 2 (iL) (Q) Figure 3 it Figure 2 (Mountain) ↑ ↑ ↑ ↑

Claims (1)

[Claims] Equipped with a fixed blade that converts the flow of fluid into a swirling flow, a magnetic ball that rotates due to the swirling flow, a rotation speed detection device that detects the rotation speed of this ball, and a temperature detector that detects the temperature of the fluid, A flow rate detection device comprising calculation means for calculating and outputting a flow rate from the signal of the rotation speed detection device and the signal of the temperature sensor.