JPH05133343A - Variable speed water supply device - Google Patents

Abstract

PURPOSE:To prevent a pressure drop in a pump delivery port even in the case of abnormally high forced pressure by continuing operation control by replacing the second pressure value with a pressure signal in the case that a pressure signal value from the second pressure detecting means exceeds the second pressure value of the second pressure setting means. CONSTITUTION:A supply water pump 3, variable speed electric motor 2, first/ second pressure detecting means 9, 9X and the first/second pressure setting means 101, 102 are provided. A target pressure arithmetic means 6 of calculating a target pressure, corresponding to a rotational speed S1, to output a target pressure signal S3 is provided, and further a rotational speed control means 7 for controlling a speed, so that the target pressure signal S3 agrees with a pressure signal S2, is provided. Particularly in the case that a value of pressure signal S2X from the second pressure detecting means 9X exceeds a value of the second pressure PB of the second pressure setting means 102, the second pressure PB is replaced with the pressure signal S2X to continue operation control. In this way, even when a forced pressure is increased a range wherein a pump speed becomes zero is decreased not to generate pressure drop.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls the speed of the pump by controlling the speed of the pump while successively calculating an appropriate target pressure from the rotational speed of the pump so as to control the pressure on the secondary side of the pump so that the end pressure becomes constant. The present invention relates to a variable speed water supply device.

[0002]

2. Description of the Related Art Conventionally, by controlling the speed of a pump while successively calculating an appropriate target pressure from the rotational speed of the pump, the pressure on the secondary side of the pump can be kept constant without using an expensive flow meter. Controllable variable speed water supply devices are known. Such a variable speed water supply device is effective in a piping system having a water receiving tank or the like on the primary side of the pump and in which the pushing pressure does not change so much, but in other words, a piping system in which the pump is directly connected to pressurize in the middle of the piping, in other words, In a piping system in which the pressure on the primary side of the pump significantly changes depending on the usage state of water, it is difficult to control the pressure on the secondary side of the pump so that the terminal pressure becomes constant.

Therefore, the pressure detecting means provided on the primary side of the pump is used to correct the control equation so that the pressure on the secondary side of the pump is kept constant even if the pressure on the primary side of the pump changes depending on the usage condition of water. A controlled variable speed water supply is conceivable. FIG. 2 is a block diagram showing the configuration of this variable speed water supply device.

In FIG. 2, reference numeral 3 is a water supply pump, and the water supply pump 3 is driven by a variable speed electric motor 2 composed of a motor and an inverter. The rotation speed of the variable speed electric motor 2 is output by the rotation speed detection means and is output to the target pressure calculation means that outputs the rotation speed signal S1 representing the rotation speed. The first pressure detection means 9 detects the water pressure in the discharge pipe 8 of the water supply pump 3 and outputs a pressure signal S2 representing the water pressure to the rotation speed control means.

Further, 101 is a first pressure setting means for setting a first set pressure PA, and 102 is the first pressure PA.
Second pressure setting means for setting a lower second set pressure PB, 103 is a third pressure setting means for setting a pump cutoff pressure P0
The pressure setting means 9X is a second pressure detecting means for detecting the water pressure in the suction pipe 10 provided in the suction pipe 10 of the water supply pump 3 and outputting the pressure signal S2X representing the water pressure.

Further, the target pressure calculating means 6 is a target pressure P corresponding to the rotation speed represented by the rotation speed signal S1.
V is calculated by using the pressure signal S2X, and a target pressure signal S3 representing the target pressure PV is output to the rotation speed control means 7. The rotation speed control means 7 is responsive to the target pressure signal S3 and the pressure signal S2 and responds to the target pressure represented by the target pressure signal S3 with the pressure signal S2.
The speed of the variable electric motor 2 is controlled so that the pressures represented by 1 and 2 match.

[0007]

However, the variable speed water supply device having the structure shown in FIG. 2 also has the following problems. This problem will be described below with reference to the time chart of FIG.

Pushing pressure (pump primary side (suction side) pressure)
Increases extremely, and the target pressure PV at that time (P depending on the flow rate
B ≦ PV ≦ PA), the pump speed becomes zero as indicated by * A in FIG. When the pump speed becomes zero, the target pressure PV becomes the second set pressure PB. Therefore, when the pushing pressure decreases after the pump speed once becomes zero, the pushing pressure is equal to or lower than the second set pressure PB. The speed does not increase until it becomes (* 3 in Figure 3). Therefore, at the point B, there is a problem that the discharge pressure of the water supply pump falls below the target pressure PV, resulting in a pressure drop.

The above problem will be described with reference to the pressure / flow rate curve diagram of FIG. 4. In the variable speed water supply system having the configuration shown in FIG.
As shown in FIG. 4, the curve of the target pressure PV is the pushing pressure,
That is, the second pressure detecting means 9X that represents the water pressure in the suction pipe 10.
Since the pressure signal S2X, which is the output of the above, does not change even if it rises, the range where the pump speed becomes zero becomes large as shown by the hatched line in FIG.

The present invention has been made in view of the above points, and eliminates the above problems and reduces the range in which the pump speed becomes zero even when the pushing pressure of the water supply pump rises, thereby reducing the discharge force of the water supply pump. It is an object of the present invention to provide a variable speed water supply device in which the pressure falls below the target pressure PV and the pressure does not drop.

[0011]

In order to solve the above problems, the present invention is directed to a water supply pump 3, a variable speed electric motor 2 for driving the pump 3, and a rotation speed of the variable speed electric motor 2, as shown in FIG. And a discharge pipe 8 of the water supply pump 3 for detecting the rotation speed and outputting a rotation speed signal S1 indicating the rotation speed.
The first pressure detecting means 9 for detecting the water pressure and outputting a pressure signal S2 representing the water pressure, the first pressure setting means 101 for setting the first pressure PA, and the first pressure PA. Second pressure setting means 102 for setting a low second pressure PB and second pressure detecting means provided in the suction pipe 10 of the water supply pump 3 for detecting water pressure and outputting a pressure signal S2X representing the water pressure. 9X and a target pressure calculating means for calculating a target pressure PA corresponding to the rotation speed represented by the rotation speed signal S1 by using the pressure signal S2X and outputting a target pressure signal S3 representing the target pressure PA. 6, in response to the target pressure signal S3 and the pressure signal S2, the variable electric motor 2 is controlled so that the pressure represented by the pressure signal S2 matches the target pressure represented by the target pressure signal S3. Speed control A variable-speed water supply device provided with the rotation speed control 7, wherein the value of the pressure signal S2X from the second pressure detection means 9X exceeds the value of the second pressure PB of the second pressure setting means 102. Represents the second pressure PB to the pressure signal S
It is characterized in that the operation control is continued by replacing with 2X.

[0012]

As described above, the value of the pressure signal S2X from the second pressure detecting means 9X is the second value of the second pressure setting means 102.
When the value of the pressure PB exceeds the value of the second pressure PB, the second pressure PB is replaced with the pressure signal S2X to continue the operation control so that the pressure signal S2X (pushing pressure) becomes the second set pressure PB.
When the pressure exceeds the second set pressure PB (PBX = PB), the pump speed does not become zero until the push pressure S2X becomes equal to or higher than the set pressure PA.
The target pressure PV is slightly higher than that when there is no pushing pressure, but the target pressure PV is maintained while maintaining the pressure. When the pushing pressure S2X exceeds the first set pressure PA, the pump speed becomes zero.
After that, when the pushing pressure S2X becomes equal to or lower than the first set pressure PA, the pump speed is increased, and the correct target pressure PV is transitioned again until it becomes equal to or lower than the second set pressure PB. Thus, even if there is an abnormally high pushing pressure, the pressure drop at the point B can be avoided.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 variable speed water supply device of the present invention. In FIG. 1, the same reference numerals and parts as those in FIG. 2 indicate the same parts, and therefore the description thereof will be omitted.

The configuration of the variable speed water supply apparatus of FIG. 1 differs from that of FIG. 2 in that the variable speed water supply apparatus of FIG. 1 has a comparison selection means 11 and a second pressure setting means 102 of the second type.
Value of the pressure PB and the value of the pressure signal S2X from the second pressure detecting means 9X are compared, and the signal with the larger value is PB
It is the point where X is output to the target pressure calculation means 6 and the point where the third pressure setting means 103 of FIG. 2 is not provided. Other than that, the variable speed water supply apparatus of FIG. 1 and the variable speed water supply apparatus of FIG. 2 have the same configuration. That is, in the variable speed water supply apparatus of FIG. 1, when the value of the pressure signal S2X from the second pressure detecting means 9X exceeds the value of the set pressure PB of the second pressure setting means 102, the second pressure PB is reached. Is replaced with the pressure signal S2X to continue the operation control.

The operation of the variable water supply system shown in FIG. 1 will be described with reference to the flow chart shown in FIG. First, the target ena remaining means 6 reads the value of the set pressure PA of the first pressure setting means 101 and the value of the set pressure PB of the second pressure setting means 102, and the discharge pipe 8 by the first pressure detecting means 9 is read. The value of the pressure signal S2 in the inside and the pressure signal S2X in the suction pipe 10 by the second pressure detecting means 9X are read (step ST
1) Then, it is judged whether or not the set pressure PB is larger than the pressure signal S2X (PB> S2X). If NO, the output PBX of the comparison / selection means 11 is PBX = S2X (step ST2), and if YES. Becomes PBX = PB (step ST3).

Subsequently, the target calculation functions K1 and K2 are determined (step ST5), the calculation for obtaining the target pressure PV is performed, and the pressure signal S3 representing the target pressure PV is output to the rotation speed control means 7 (step ST6). Rotation speed control means 7
Is the current pressure S in the discharge pipe 8 from the first pressure detecting means 9.
2 and the target pressure PV (pressure signal S3), the speed value of the pump is calculated and obtained and output to the inverter of the variable speed electric motor 2.

6 and 7 are a time chart and a pressure / flow rate curve diagram for explaining the operation of the variable water supply apparatus of FIG. In FIG. 6, when the pushing pressure S2X (internal pressure of the suction pipe 10 by the second pressure detecting means) exceeds the second setting pressure PB, the second setting pressure PB is set to the pushing pressure (PBX =
PB), the pump speed does not become zero, and until the pushing pressure S2X becomes equal to or higher than the first set pressure PA of the second pressure setting means 101, the target is slightly higher than in the case where there is no pushing pressure. Although it is the pressure PV, it changes while maintaining the pressure. When the pushing pressure S2X exceeds the first set pressure PA, the pump speed becomes zero.

After that, the pushing pressure S2X is the first set pressure P.
When the pressure becomes equal to or lower than A, the pump speed is increased, and the correct target pressure PV is transitioned again until the pressure becomes equal to or lower than the second set pressure PB. Thus, even if there is an abnormally high pushing pressure, the pressure drop at the point B can be avoided.

As seen from the pressure-flow rate curve diagram of FIG. 7, when the value of the pushing pressure S2X exceeds the value of the second set pressure PB, the output PBX of the comparison / selection means 11 is changed from the second pressure PB to the pressure signal S2X. Since the target pressure PV curve is changed as shown by D2 and D3, the range where the pump speed becomes zero like the shaded portion in FIG. 4 is eliminated.

[0020]

As described above, according to the present invention, the value of the pressure signal S2X from the second pressure detecting means 9X is the second value.
When the value of the second pressure PB of the pressure setting means 102 is exceeded, the second pressure PB is replaced with the pressure signal S2X to continue the operation control, so that the pump can be operated even when there is an abnormally high pushing pressure. An excellent effect is obtained in that the pressure drop at the discharge port can be avoided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a variable speed water supply device of the present invention.

FIG. 2 is a block diagram showing the configuration of a variable speed water supply device before the present invention.

FIG. 3 is a diagram showing a time chart for explaining the operation of the variable speed water supply system shown in FIG.

FIG. 4 is a pressure-flow curve diagram for explaining the operation of the variable speed water supply system shown in FIG.

FIG. 5 is a view showing a flowchart for explaining the operation of the variable speed water supply system of the present invention.

FIG. 6 is a diagram showing a time chart for explaining the operation of the variable speed water supply apparatus of the present invention.

FIG. 7 is a pressure flow rate curve diagram for explaining the operation of the variable speed water supply system of the present invention.

[Explanation of symbols]

 2 Variable speed electric motor 3 Water supply pump 5 Rotational speed detection means 6 Target pressure calculation means 7 Rotational speed control means 8 Discharge pipe 9 First pressure detection means 10 Suction pipe 11 Comparison selection means 101 First pressure setting means 102 Second Pressure setting means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayoshi Ikeda 1-3-1 Ginza, Chuo-ku, Tokyo Ebara Densan Co., Ltd.

Claims (1)

[Claims] 1. A water feed pump 3, a variable speed electric motor 2 for driving the water feed pump 3, a rotational speed of the variable speed electric motor 2, and a rotational speed for outputting a rotational speed signal S1 representing the rotational speed. Detection means 5
A first pressure detecting means 9 provided in the discharge pipe 8 of the water supply pump 3 for detecting the water pressure in the discharge pipe 8 and outputting a pressure signal S2 representing the water pressure; and a first pressure PA. First pressure setting means 101 to be set
A second pressure setting means 102 for setting a second pressure PB lower than the first pressure PA; and a suction pipe 10 provided in the suction pipe 10 of the water supply pump 3.
Second pressure detecting means 9X for detecting the water pressure in the inside and outputting a pressure signal S2X representing the water pressure, and the target pressure PV corresponding to the rotation speed represented by the rotation speed signal S1 is the pressure signal S2X. Target pressure calculation means 6 for outputting a target pressure signal S3 representing the target pressure PV calculated by using the target pressure signal S3 and the target pressure signal S3 in response to the target pressure signal S3 and the pressure signal S2. A variable speed water supply device provided with rotation speed control means 7 for controlling the speed of the variable electric motor 2 so that the pressure represented by the pressure signal S2 coincides with the target pressure. When the value of the pressure signal S2X from the pressure detecting means 9X exceeds the value of the pressure PB of the second pressure setting means 102, the second pressure PB is replaced with the pressure signal S2X to continue the operation control. Variable speed water supply equipment to.