JP3191015B2 - Variable speed water supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls the speed of a pump while calculating an appropriate target pressure based on the rotation speed of the pump, thereby controlling the pressure on the secondary side of the pump so that the terminal pressure becomes constant. It relates to a variable speed water supply device.

[0002]

2. Description of the Related Art Conventionally, by controlling the speed of a pump while calculating an appropriate target pressure more than the rotation speed of the pump, the pressure on the secondary side of the pump can be kept constant without using an expensive flow meter. Variable speed water supply devices to be controlled 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 much, but a piping system in which the pump is directly connected in the middle of the piping and pressurized, in other words, In a piping system in which the pressure on the primary side of the pump changes remarkably depending on the use condition of water, it has been difficult to control the pressure on the secondary side of the pump so that the terminal pressure is constant.

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

In FIG. 2, reference numeral 3 denotes a water supply pump, and the water supply pump 3 is driven by a variable speed motor 2 composed of a motor and an inverter. Rotational speed of the variable speed electric motor 2 is Outputs by the rotational speed detection means 5, and outputs a rotational speed signal S1 representing the rotational speed to the target pressure calculating means 6.
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.

[0005] Also, 101 is first pressure setting means for setting a first set pressure PA, and 102 is the first pressure PA.
A second pressure setting means 103 for setting a second set pressure PB lower than the third set pressure PB;
The pressure setting means 9X is a second pressure detecting means for detecting a water pressure in the suction pipe 10 provided in the suction pipe 10 of the water supply pump 3 and outputting a pressure signal S2X representing the water pressure.

The target pressure calculating means 6 calculates 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 responds to the target pressure signal S3 and the pressure signal S2 and responds to the target pressure represented by the target pressure signal S3.
The speed of the variable electric motor 2 is controlled so that the pressures represented by

[0007]

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

Indentation pressure [Primary side of pump (suction side) pressure]
Rises extremely, and the target pressure PV (at that time, P
B ≦ PV ≦ PA vary) exceeds the pump speed, as shown in A ※ in FIG 3 is zero. When the pump speed becomes zero, the target pressure PV becomes the second set pressure PB. Therefore, when the pump speed once becomes zero and then the pushing pressure decreases, the pushing pressure becomes equal to or less than the second set pressure PB. The speed does not increase until it becomes (* B in FIG. 3). Therefore,
At point B, there is a problem that the discharge pressure of the water supply pump 3 becomes lower than the target pressure PV, and the pressure drops.

The above problem will be described with reference to a pressure flow curve diagram of FIG. 4. In the variable speed water supply device having the structure shown in FIG.
As shown in FIG. 4, the curve of the target pressure PV is the indentation pressure,
That is, the second pressure detecting means 9X representing the water pressure in the suction pipe 10
4 does not change even if the pressure signal S2X, which is the output of the pump, rises, the range where the pump speed becomes zero as shown by the hatching in FIG. 4 becomes large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made to eliminate the above problems, to reduce the range in which the pump speed becomes zero even when the feed pressure of the water supply pump increases, and to reduce the discharge power of the water supply pump. It is an object of the present invention to provide a variable speed water supply apparatus in which the pressure does not fall below the target pressure PV and the pressure does not drop.

[0011]

According to the present invention, there is provided a water supply pump 3, a variable speed motor 2 for driving the pump 3, and a rotation speed of the variable speed motor 2, as shown in FIG. Rotation speed detecting means 5 for detecting rotation speed and outputting a rotation speed signal S1 representing the rotation speed;
A first pressure detecting means 9 for detecting a water pressure and outputting a pressure signal S2 representing the water pressure, a first pressure setting means 101 for setting a first pressure PA, and a first pressure PA. Pressure setting means 102 for setting a lower 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. A target pressure PA corresponding to the rotation speed represented by the rotation speed signal S1 by calculating using the pressure signal S2X, and outputting a target pressure signal S3 representing the target pressure PA. 6, the variable electric motor 2 in response to the target pressure signal S3 and the pressure signal S2 such 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 a rotation speed control 7 and 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 Calculates the second pressure PB as a 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 determined by the second pressure setting means 102.
When the pressure PB exceeds the value of the pressure PB, the second pressure PB is replaced with the pressure signal S2X and the operation control is continued, so that the pressure signal S2X (push-in pressure) becomes the second set pressure PB.
Is exceeded, the second set pressure PB is set as the pushing pressure (PBX = PB). Therefore, the pump speed does not become zero and the pushing pressure S2X becomes equal to or higher than the set pressure PA.
The target pressure PV, which is slightly higher than the case where there is no indentation pressure, is maintained while maintaining the pressure. When the pushing pressure S2X exceeds the first set pressure PA, the pump speed becomes zero.
Thereafter, when the pushing pressure S2X becomes equal to or less than the first set pressure PA, the pump speed is increased, and the pressure changes to the correct target pressure PV again until it becomes equal to or less 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]

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 the variable speed water supply device of the present invention. In FIG. 1, portions denoted by the same reference numerals and the same reference numerals as those in FIG.

The configuration of the variable speed water supply device of FIG. 1 is different from that of FIG. 2 in that the variable speed water supply device of FIG.
Is compared with the value of the pressure signal S2X from the second pressure detecting means 9X, and the signal having the larger value is referred to as PB
The point X is output to the target pressure calculating means 6 and the point that the third pressure setting means 103 in FIG. 2 is not provided. Otherwise, the variable speed water supply device of FIG. 1 and the variable speed water supply device 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 replaced by the pressure signal S2X, and the operation control is continued.

The operation of the variable speed water supply device of FIG. 1 will be described with reference to the flowchart shown in FIG. First, the target pressure
The calculating 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 reads the discharge pipe 8 by the first pressure detecting means 9.
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 ST1), and subsequently, whether or not the set pressure PB is larger than the pressure signal S2X (PB> S2X) Is determined (step ST
2) In the case of NO, the output PBX of the comparison and selection means 11 is PB
X = S2X next (step ST 4), in the case of YES the PBX = PB (step ST3).

Subsequently, the target calculation functions K1 and K2 are determined (step ST5), a calculation for obtaining the target pressure PV is performed, and a 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 output to the inverter of the variable speed motor 2.

FIGS. 6 and 7 are a time chart and a pressure flow curve diagram for explaining the operation of the variable water supply apparatus shown in FIG. In FIG. 6, at the time when the pushing pressure S2X (the internal pressure of the suction pipe 10 by the second pressure detecting means) exceeds the second set pressure PB, the second set pressure PB is reduced to the pushing pressure (PBX =
PB), the pump speed does not become zero, and the target is slightly higher than the case without the pushing pressure until the pushing pressure S2X becomes equal to or higher than the first set pressure PA of the second pressure setting means 101. The pressure PV changes while maintaining the thigh pressure. When the pushing pressure S2X exceeds the first set pressure PA, the pump speed becomes zero.

Thereafter, the pushing pressure S2X is set to the first set pressure P
When the pressure becomes equal to or less than A, the pump speed is increased, and changes to the correct target pressure PV again until the pressure becomes equal to or less 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.

Referring to the pressure flow curve diagram of FIG. 7, when the value of the indentation 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. And the target pressure PV curve is changed as shown by D2 and D3, so that there is no range where the pump speed becomes zero as indicated by the hatched portion in FIG.

[0020]

As described above, according to the present invention, the value of the pressure signal S2X from the second pressure detecting means 9X is equal to the second signal.
When the second pressure PB exceeds the value of the second pressure PB of the pressure setting means 102, the second pressure PB is replaced with the pressure signal S2X and the operation control is continued. An excellent effect that a pressure drop at the discharge port can be avoided can be obtained.

[Brief description of the 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 a configuration of a variable speed water supply apparatus before the present invention.

FIG. 3 is a diagram showing a time chart for explaining the operation of the variable speed water supply device shown in FIG. 2;

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

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

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

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

[Explanation of symbols]

 Reference Signs List 2 variable speed motor 3 feed water pump 5 rotation speed detection means 6 target pressure calculation means 7 rotation 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

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masayoshi Ikeda 1-3-1 Ginza, Chuo-ku, Tokyo Ebara Densan Co., Ltd. (56) References JP-A-58-104391 (JP, A) 1986-57193 (JP, U) Kawamoto Pump 50Hz Automatic Water Supply System Catalog, issued August 1, 1989, Kawamoto Manufacturing Co., Ltd. (58) Fields investigated (Int. Cl. ⁷ , DB name) F04B 49/06 321

Claims (1)

(57) [Claims] 1. The suction side has no water receiving tank, and the pressure on the suction side is
A water supply pump 3 directly connected in the middle of piping that changes significantly ,
A variable speed motor 2 for driving the water supply pump 3; a rotation speed detecting means 5 for detecting a rotation speed of the variable speed motor 2 and outputting a rotation speed signal S1 representing the rotation speed; The discharge pipe 8 is provided on the discharge pipe 8.
A first pressure detecting means 9 for detecting a water pressure in the inside and outputting a pressure signal S2 representing the water pressure, and a first pressure PA for setting a first pressure PA which is an upper limit value of a target pressure PV which changes according to a flow rate.
Pressure setting means 101, a second pressure setting means 102 for setting a second pressure PB which is a lower limit value of a target pressure PV which varies according to a flow rate, and a suction side pipe 10 provided for the water supply pump 3. A pressure signal S2 representing the water pressure by detecting the water pressure in the side pipe 10
And a second pressure detecting means 9X for outputting X, wherein a target pressure PV corresponding to the rotation speed represented by the rotation speed signal S1 is calculated by using the pressure signal S2X and represents the target pressure PV. A target pressure calculating means 6 for outputting a target pressure signal S3; and a response to the target pressure signal S3 and the pressure signal S2 in response to the target pressure represented by the target pressure signal S3. And a rotation speed control means 7 for controlling the speed of the variable speed motor 2 so that the pressures to be matched are equal to each other, to constitute a variable speed water supply device. The value of the pressure signal S2X from the second pressure detection means 9X When the pressure exceeds the value of the pressure PB of the second pressure setting means 102, the second pressure PB is replaced with a pressure signal S2X and the operation control is continued, wherein the variable speed water supply device is characterized.