JP2000205982A - Pressure detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect both pressures within different regions by means of a relatively simple arrangement. SOLUTION: A pressure sensor 26 is provided so that pressure matching the level of water in a bathtub works during the feed of hot water, and so that pressure within a line works during inspection for water leaks. The pressure sensor 26 outputs a voltage signal Vout of magnitude proportional to the pressure detected, and the signal is directly input to a control device as a first signal Vout 1 and is amplified by an amplifying circuit 27 comprising a negative feedback circuit, so that it is input to the control device as a second signal Vout 2. For the first signal Vout 1, detection signals relating to a high pressure region suited for the inspection for water leaks are output in a large span, while for the second signal Vout 2, detection signals related to a low pressure region suited for water level measurements are output in a large span. The control device uses the first signal Vout 1 for the inspection of the line for water leaks and uses the second signal Vout 2 in measuring the level of water in the bathtub.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure detecting device capable of accurately detecting the pressure in a pipe through which a fluid flows in two types of regions, a high pressure region and a low pressure region.

[0002]

For example, in a hot water supply apparatus installed in a general house or an apartment, a pressure in a pipe communicating with a bathtub is detected by a semiconductor pressure sensor, and the detected water pressure in the bathtub (and, consequently, water pressure) is detected. The microcomputer is configured to control the hot water supply level based on the water level). In this case, the relationship between the water pressure and the detection signal (voltage) output from the pressure sensor is as shown in FIG. 5. For example, the pressure in the range of −0.7 to 1.0 kgf / cm ² is By detecting at a span of about 4 V (0.5 to 4.5 V), water pressure (water level) detection with high resolution and high accuracy is performed.

[0003] In recent years, in the above-described hot water supply apparatus, it has been demanded to add a function of water leak inspection of pipes (automatic determination of the presence or absence of water leak) when, for example, the hot water supply apparatus is installed. This water leak test is performed, for example, until all the outlets of the water (hot water) in the pipe are closed, and the pipe is filled with water until a predetermined pressure (for example, 1-3 kgf / cm ² which is a general tap water pressure) is reached. Is supplied, and after the pressure reaches a predetermined value, the measurement is performed based on measuring how much the pressure in the pipe decreases after a certain period of time.

However, in order to add such a function of water leak inspection (automatic determination), a pressure sensor for detecting the pressure in the pipe is required. Therefore, the above-described pressure sensor for detecting the water level cannot be used also for the water leak inspection. In this case, even if the detection range of the pressure sensor is widened, the resolution is reduced and the water level detection accuracy is significantly deteriorated. For this reason, as shown in FIG. 6, two pressure sensors 1 and 2 for detecting the water level of the bathtub and for inspecting the water leak are required, resulting in disadvantages such as an increase in cost.

Therefore, in order to solve such a problem,
Recently, a pressure sensor exhibiting characteristics as shown in FIG. 7 has been considered. This pressure sensor has a detection area of -0.7 to 1.0 kgf / cm ² by a built-in processing circuit,
In other words, the measurement range is automatically switched between the detection range of 1.0 to 3.0 kgf / cm ² . Thus, even with a single pressure sensor, the water level can be detected in the lower detection area, and a water leak test can be performed in the higher detection area.

[0006] However, in the pressure sensor shown in FIG.
/ Cm ^{2 over} a span of about 3 V (0.5-3.
5V), the resolution is inferior to that shown in FIG. 5, and the accuracy of detecting the water level is lowered. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pressure detection device capable of accurately detecting both pressures in different regions with a relatively simple configuration.

[0007]

A pressure detecting device according to the present invention receives a pressure in a pipe through which a fluid flows, converts the pressure into an electric signal and outputs the signal, and a pressure sensor based on an output signal from the pressure sensor. Pressure determination means for determining the pressure by the pressure sensor. The output signal from the pressure sensor is directly input to the pressure determination means as a first signal, and the output signal from the pressure sensor is amplified by an amplifier circuit. And a pressure judging means for judging a pressure in a high pressure region based on the first signal, and a pressure judgment in a low pressure region lower than the high pressure region. The present invention is characterized in that it is configured to be performed based on the second signal (the invention of claim 1).

According to this, the output signal from the pressure sensor is output as two kinds of signals, the first signal corresponding to the high pressure region and the second signal obtained by amplifying the output signal. . At this time, the second signal is obtained by amplifying the output signal from the pressure sensor by the amplifier circuit.
The second signal may be a signal corresponding to a low-pressure region, such as when the detection range is switched from the high-pressure region to a low-pressure region lower than the high-pressure region.

Therefore, by setting the amplification degree of the amplifier circuit to an appropriate value, even a single pressure sensor can detect the pressure with sufficiently high resolution in both the high-pressure region and the low-pressure region. As a result, according to the first aspect of the invention, there is an excellent effect that both pressures in different areas can be accurately detected with a relatively simple configuration.

In this case, the amplifying circuit can be provided on the pressure judging means side (the invention of claim 2), so that it is not necessary to change the signal processing circuit in the pressure sensor, the number of terminals, and the like. Therefore, the versatility of the pressure sensor can be secured. Alternatively, the amplifier circuit may be integrated into the sensor chip of the pressure sensor (the invention of claim 3), whereby the configuration can be simplified.

[0011] More specifically, the pressure detecting device of the present invention can be used by being incorporated into a hot water supply device.
At this time, it is possible to adopt a configuration in which the first signal is used for water leak inspection of the pipe and the second signal is used for measuring the water level of the bathtub. According to this, 1
Since the pressure sensors can be used for both a water leak inspection and a water level measurement having different detection pressure regions, detection can be performed with high resolution and high accuracy for both of them with a simple configuration.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a hot water supply apparatus installed in, for example, a general house or an apartment will be described below with reference to FIGS.
This embodiment corresponds to claims 1, 2, and 4.
FIG. 3 schematically shows a main configuration of the hot water supply apparatus according to the present embodiment, and FIG. 4 schematically shows an electric configuration of the hot water supply apparatus.

First, as shown in FIG. 3, a water supply pipe 12 from a water source (water supply) is connected to the hot water supply apparatus main body 11. The tip of the water pipe 12 is connected to the switching valve 1
3 and the switching valve 13 is connected to a base end of a hot water supply pipe 14. This hot water supply pipe 14
Extends from the hot water supply device main body 11 to the bathtub 15 in the bathroom, and its tip is connected to a hot water supply port 16 on the side of the bathtub 15. The hot water supply device body 11 is provided with a gas burner 17 for heating water passing through the hot water supply pipe 14 into hot water.

A suction port 18 is provided at a portion of the side of the bathtub 15 near the bottom, and the base end of a pipe 19 for additional cooking is connected to the suction port 18. The additional cooking pipe 19 extends to the hot water supply device main body 11, and a distal end thereof is connected to the switching valve 13. Further, a circulation pump 20 is provided in the hot water supply device main body 11 at an intermediate position of the additional cooking pipe 19.

On the other hand, as shown in FIG. 4, the water heater is provided with a control device 21 mainly composed of a microcomputer. The control device 21 includes the switching valve 13,
The gas burner 17 and the pump 20 are controlled. Also, an operation panel (remote control) 24 having a key operation unit 22, a display unit 23, a buzzer (not shown), and the like is connected to the control device 21, and the key operation unit 22 controls temperature setting, water level setting, hot water supply, and the like. An operation signal for execution and the like is input, and a necessary display on the display unit 23 is controlled. Further, a signal from a temperature sensor 25 for detecting the temperature of hot water in the bathtub 15 is input to the control device 21.

The pressure detector according to the present embodiment is incorporated in the hot water supply apparatus. As described later in detail, the pressure detecting device includes a pressure sensor 26 that receives the pressure in the pipe, converts the pressure into an electric signal, and outputs the electric signal. In the present embodiment, as shown in FIG. 4, the pressure sensor 26 is provided at a position (downstream of the pump 20) where the pressure in the additional cooking pipe 19 is detected. An output signal from the pressure sensor 26 is input to the control device 21. The control device 21 determines a pressure based on an output signal (voltage) from the pressure sensor 26. It also functions as a means.

When the hot water supply is started, the control device 21 controls the switching valve 13 so that the water supply pipe 12 and the hot water supply pipe 14 communicate with each other at the start of hot water supply. At the same time, the gas burner 17 is operated so that the temperature of the hot water reaches the set temperature, and hot water is supplied from the hot water supply port 16 into the bathtub 15. As will be described later, at the time of hot water supply, the water level in the bathtub 15 is monitored based on the output signal from the pressure sensor 26, and the hot water supply is stopped when the water level in the bathtub 15 reaches the set water level. I have.

The controller 21 monitors the water level in the bathtub 15 even after the hot water supply unless the hot water supply switch is turned off, and supplies hot water when the water level drops. At the same time, the controller 21 controls the switching valve 13 when the temperature of the hot water in the bathtub 15 detected by the temperature sensor 25 decreases (or when the user instructs additional cooking). The hot water supply pipe 14 and the additional cooking pipe 19 are communicated (the distal end of the water supply pipe 12 is closed), and the gas burner 17 and the pump 20 are operated to perform additional cooking until the set temperature is reached. I have.

Further, as will be described later, the control device 21 executes a water leak inspection program based on a predetermined operation by an installation worker (serviceman), and executes piping (water supply piping 12, hot water supply piping). 14, an additional inspection pipe 19) is automatically subjected to a water leak inspection (determination of the presence or absence of water leak). Also in this water leak inspection, a determination is made based on the output signal of the pressure sensor 26.

The pressure sensor 26 is composed of a well-known semiconductor pressure sensor. Although not shown, the pressure sensor 26 has a pressure sensor chip in a casing having a pressure introduction port. The pressure sensor chip has a diaphragm formed on a single-crystal silicon substrate, and a detection circuit formed by bridge-connecting four diffusion piezoresistors whose electric resistance changes according to pressure on the upper surface of the diaphragm. It is configured. As shown in FIG. 1, the pressure sensor 26 is provided with three terminals: a power terminal, a ground terminal (GND), and an output terminal (Vout). A predetermined voltage Vcc is applied between the power supply terminal and the ground terminal by the DC power supply 31, and from the output terminal,
A voltage signal Vout having a magnitude proportional to the detected pressure is output.

The output signal from the output terminal (V
out) is input to the control device 21 (microcomputer) as it is as the first signal Vout1 via the signal line, and is branched from the signal line and input to the amplification circuit 27, where the signal is amplified by the amplification circuit 27. The second signal Vout2 is input to the control device 21 (microcomputer).
The amplifying circuit 27 includes, for example, a negative feedback circuit including an operational amplifier 28 and two resistors 29 and 30.
In the present embodiment, the amplifier circuit 27 is provided on a board on which the control device 21 is incorporated.

At this time, the pressure detected by the pressure sensor 26 and
The relationship between the first signal Vout1 and the second signal Vout2 is as shown in FIG. 2, and among them, the first signal Vou
For t1, -0.7 ~
A detection signal for a high voltage range in the range of 3.0 kgf / cm ² is output in a span of about 4 V (0.5 to 4.5 V). In this case, the upper limit of 3.0 kgf / cm ² corresponds to tap water pressure.

On the other hand, in the second signal Vout2, -0.7 to 0.7 kgf suitable for measuring the water level in the bathtub 15 is used.
The detection signal for the low-pressure region in the range of / cm ² is also output in a span of about 4 V (0.5 to 4.5 V). This range of −0.7 to 0.7 kgf / cm ² indicates that the difference between the water level and the installation altitude of the pressure sensor 26 is about 7 m.
(Corresponding to three floors of a building). As described in the following operation description, the control device 21
The first signal Vout1 is used for water leak inspection of the pipe, and the second signal Vout2 is used for measuring the water level of the bathtub 15.

Next, the operation of the above configuration will be described. When the user wants to supply hot water to the bathtub 15,
The key operation section 22 of the operation panel 24 is operated to set the water level and the temperature of the hot water, and then turn on the hot water supply switch. Then
As described above, control device 21 controls switching valve 13 and gas burner 17 to start supplying hot water from hot water supply port 16 into bathtub 15.

Here, as shown in FIG.
When the inside is empty and when the water level is extremely low, the suction port 18
Consequently, the inside of the additional cooking pipe 19 is open to the atmosphere, and the atmospheric pressure acts on the pressure sensor 26. Then, when the water level reaches a height that closes the suction port 18 indicated by the one-dot chain line A in FIG. 3, the inside of the additional cooking pipe 19 thereafter corresponds to the water level (height from A) in the bathtub 15. The pressure becomes a pressure, and a pressure corresponding to the water level B based on the water level A acts on the pressure sensor 26. Therefore, the output signal (voltage value) from the pressure sensor 26 indicates the water level in the bathtub 15.

During this hot water supply, the control device 21 constantly monitors the second signal Vout2 among the output signals from the pressure sensor 26, and when the second signal Vout2 becomes a voltage value corresponding to the set water level, the hot water supply is performed. Operation is stopped. At this time, as shown in FIG. 2, the second signal Vout2 is −0.7 to 0.7 kgf suitable for measuring the water level in the bathtub 15.
/ Cm ² is about 4 V
Is output in the span (0.5 to 4.5 V), so that the water level can be detected with high resolution and high accuracy.

On the other hand, when the above-described hot water supply device is installed, the installation worker performs a water leak inspection of the pipe (automatic determination of the presence or absence of water leak). In performing the water leak inspection, the worker closes all the ports of the pipes (in this case, the hot water supply port 16 and the suction port 18) with a lid or the like, and then causes the control device 21 to execute a water leak inspection program. At this time, the control device 21 switches all of the three members, the water supply pipe 12, the hot water supply pipe 14, and the additional cooking pipe 19, by switching the switching valve 13. Accordingly, in this state, the pressures in the pipes 12, 14, and 19 are all equal, and
The output signal (voltage value) from the pressure sensor 26 is in accordance with the pressure in the pipes 12, 14, and 19.

First, an operator operates a hand pump connected to, for example, the base end of the water supply pipe 12 to connect the pipe 1.
The water pressure is applied to the insides 2, 14, and 19.
This pressurization is performed in the pipes 12, 14, 19, for example, at 3.0 k.
The control is performed until the pressure reaches gf / cm ^2. At this time, the controller 21 monitors the first signal Vout1 among the output signals from the pressure sensor 26, and the detected pressure becomes 3.0 kgf.
/ Cm ² (4.5 V in voltage), the display unit 23
Alternatively, a buzzer or the like notifies the worker of the fact. The operator stops pressurizing at the time of the notification, and maintains the pressurized stop state.

Thereafter, the control device 21 waits for a predetermined measurement time to elapse, and after a predetermined time, reads the pressure detected by the first signal Vout1 of the pressure sensor 26 and calculates the pressure drop amount. Here, if water leakage occurs in any of the pipes 12, 14, and 19, the degree of pressure drop becomes large.
It is possible to determine whether or not water leakage has occurred based on the pressure drop amount. Also in this case, as shown in FIG. 2, the first signal Vout1 is suitable for a pipe leak test.
Since the detection signal for the high voltage range in the range of 0.7 to 3.0 kgf / cm ² is output in a span of about 4 V (0.5 to 4.5 V), the water leak inspection can be performed with high resolution and accuracy. Is what you can do.

As described above, according to this embodiment, the output signal from the pressure sensor 26 is amplified by the amplifier circuit 27 to the first signal Vout1 corresponding to the high-pressure region suitable for the water leak inspection of the pipe. And the second signal Vout2 corresponding to the low-pressure area suitable for measuring the water level in the bathtub 15 is output as two kinds of signals, so that the detection range is switched between the high-pressure area and the low-pressure area. This can be suitable for the detection of each area.

Therefore, according to the present embodiment, even with one pressure sensor 26, the pressure can be detected with sufficiently high resolution in both the high pressure region and the low pressure region, and the pressure in the high pressure region and the low pressure region can be detected. An excellent effect of enabling accurate detection of both pressures with a relatively simple configuration can be obtained. Further, in this embodiment, in particular, since the amplifier circuit 27 is provided on the control or device 21 side, there is no need to change the signal processing circuit in the pressure sensor 26, the number of terminals, etc. Can be secured.

Further, in the present embodiment, in particular, the present invention is applied to a hot water supply apparatus, and one pressure sensor 26 is configured to be able to be used for both a water leak inspection and a water level measurement having different detection pressure ranges. Therefore, it is possible to sufficiently respond to a demand for adding a function of water leak inspection (automatic determination of the presence or absence of water leak) of piping which has conventionally been expensive, at a low cost.

In the above-described embodiment, the present invention is applied to a hot water supply apparatus. For example, with respect to an air pipe of a factory or the like, an air leak is checked by applying a high pressure before the start of work, and then lower than that. Similarly, in applications such as maintaining the specified pressure or using construction equipment that uses hydraulic pressure such as cranes, apply a higher pressure before regular operation to check for oil leaks, and then maintain the specified pressure lower than that. The pressure detection device of the present invention can be applied to various uses such as applications.

In the above embodiment, the amplifier circuit 2
Although the control circuit 7 is provided on the control device 21 side, the amplifier circuit may be integrated with the sensor chip of the pressure sensor (corresponding to claim 3). Can be achieved. It is also possible to form the amplifier circuit on a separate substrate and incorporate it in the case of the pressure sensor.

In addition, various modifications can be made to the entire configuration of the hot water supply apparatus, particularly to the configuration of the piping and the position where the pressure sensor is provided, among others. Deformation is possible,
Further, the present invention can be appropriately modified and implemented without departing from the gist, for example, the specific values of the above-described range of the detected pressure, the voltage of the output signal, the amplification degree, and the like are merely examples.

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is a diagram illustrating an electrical configuration of a pressure sensor and an amplifier circuit.

FIG. 2 is a diagram illustrating a relationship between a detection pressure of a pressure sensor and a first signal Vout1 and a second signal Vout2.

FIG. 3 is a diagram schematically showing a configuration of a main part of the hot water supply device.

FIG. 4 is a block diagram showing an electrical configuration of the water heater.

FIG. 5 shows a conventional example, and is a diagram showing a relationship between a detection pressure of a pressure sensor and an output signal.

FIG. 6 is a diagram showing an electrical configuration when two pressure sensors are provided.

FIG. 7 is a diagram corresponding to FIG. 5, showing another conventional example.

[Explanation of symbols]

In the drawing, 11 is a hot water supply main body, 12, 14, 19 are pipes, 15 is a bathtub, 18 is a suction port, 21 is a control device (pressure determining means), 22 is a key operation unit, 26 is a pressure sensor, and 27 is an amplifier. 1 shows a circuit.

Claims (4)

[Claims] An apparatus for detecting pressure in a pipe through which a fluid flows in at least two types of areas, a high-pressure area and a low-pressure area lower than the high-pressure area, wherein the apparatus receives the pressure in the pipe and reduces the pressure. A pressure sensor that converts the pressure into an electric signal and outputs the pressure signal; and a pressure determination unit that determines a pressure based on the output signal from the pressure sensor. The output signal from the pressure sensor is directly applied to the pressure determination unit. While being input as a first signal, an output signal from the pressure sensor is amplified by an amplifier circuit to generate a second signal.
The pressure determination means performs the pressure determination for the high pressure region based on the first signal, and the pressure determination for the low pressure region to the second signal. A pressure detection device characterized in that the pressure detection is performed on the basis of the pressure. 2. The pressure detection device according to claim 1, wherein the amplification circuit is provided on the pressure determination unit side. 3. The pressure detection device according to claim 1, wherein the amplification circuit is integrated into a sensor chip of the pressure sensor. 4. The water heater according to claim 1, wherein said first signal is used for water leakage inspection of piping.
The pressure detection device according to claim 1, wherein the second signal is configured to be used for measuring a water level of a bathtub.