JPH0123674B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method of operating a variable speed water supply pump in which the amount of water is stopped at an extremely low level.

The conventional operating method of variable speed water supply pumps that stop the flow of water at extremely low levels is to install a pressure tank in the water channel and a flow switch, since operating power is wasted when the amount of water used decreases. When this lasts for a certain period of time, the water supply pump is stopped, and during that time the water supply is supplemented with water stored in the pressure tank. In this case, the pump's stop pressure becomes the specified water supply pressure, and the final pressure stored in the pressure tank is also that value. Become. On the other hand, the minimum pressure required for a water supply piping system is slightly lower than the normal water supply pressure, and if you try to start the pump at a pressure lower than that pressure, there will be places where water will not come out, and it is not practical. There may be cases where the pressure in the piping does not drop due to the lift height and it cannot be started.

Therefore, the pressure range in which water can be supplied by a pressure tank is very limited, and the effective volume cannot be large enough, and the pump starts up as soon as water is used during that time.

Also, if you want to limit the startup frequency, a large pressure tank will be required. That is, it has the following drawbacks.

(1) Since the pressure range for stopping and starting the pump cannot be wide enough, the pump starts up quickly in a small-capacity pressure tank, which increases the frequency of starting and causes problems in the durability of the pump. Moreover, the operating time becomes longer and energy saving is not achieved.

(2) Attempting to solve (1) requires a large-capacity pressure tank, which becomes expensive.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to eliminate the drawbacks of the conventional variable speed pump operating method described above, and to provide a variable speed pump operating method that allows a large effective volume of the pressure tank and a high stopping pressure of the pump. It is something.

Hereinafter, the operating method of the present invention will be explained using the drawings. FIG. 1 is an embodiment showing a piping system for carrying out the present invention. Water is pumped up from a foot valve 2 in a water tank 1 through a water suction pipe 3 by a water supply pump 5 driven by a variable speed motor 4 and is supplied through a water supply pipe 6. Although not shown, the water pipes 6 usually branch toward their ends and each end at a water tap. First, a flow switch 7 is inserted into the water pipe 6, and the water in the water pipe 6 is stored in a pressure tank 9 via a branch pipe 8. A pressure detector 11 is attached to the branch pipe 8 to measure the pressure. The pressure in the tank 9, ie, the pressure in the water pipe on the pump side, is detected.

The flow switch 7 is a water supply pump 5 to the water pipe 6
When the discharge amount becomes less than the set amount of water, the system operates and the signal is sent to a control device 12 that includes, for example, a microcomputer, an amplifier circuit, and an output circuit. The signal from the pressure detector 11 is sent to the control device 12, and from the control device 12, the signal is sent to the variable feed motor 4.
wired to send power to.

When the amount of water used at the end of the water supply pipe exceeds the set water amount of the flow switch 7, the water supply pump 5 is continuously driven by the variable speed motor 4, and when the amount of water used increases and the water pressure in the water pipe 6 decreases, the pressure detector 11 is activated. detects a drop in water supply pressure and operates, and the signal is sent to control device 1.
2, the control device 12 sends electric power to the variable speed motor 4 in order to increase the speed of the variable speed motor 4.
rotates at an increased speed, and similarly, the speed of the water supply pump 5 is increased and the discharge amount of the water supply pump 5 increases. The water supply pressure increases and the signal of the pressure detector 11 is restored to the specified water supply pressure.The signal is sent to the control device 12, which rotates the variable speed motor 4 at a speed appropriate to that time, and the discharge pressure of the water supply pump 5 is set to the specified value. value. When the amount of water used decreases, the water pressure in the water pipe 6 increases and the pressure detector 11
detects the increase in water supply pressure and sends the signal to the control device 12.
The control device 12 sends electric power to decelerate the variable speed motor 4, and the variable speed motor 4 decelerates.
The water supply pump 5 decelerates and the discharge amount decreases, and the signal of the pressure detector 11 returns to the specified water supply pressure.
The water supply pump 5 is rotated by the signal via the control device 12. The above operating method is the same as the conventional example.

If water is supplied below the specified minimum water flow rate, the rotational speed of the variable speed motor 4 and water supply pump 5 will drop and the efficiency will become extremely low, so set the flow switch 7 at such a flow rate. . When the flow switch 7 operates below the specified minimum water level, the signal is sent to the control device 12, and when the signal continues for a certain period of time or more, the control device 12 controls the variable speed motor 4.
Electric power is sent to increase the speed of the variable speed motor 4, the water supply pump 5 rotates at an increased speed, and the discharge amount increases. Since the amount of water sent through the water pipe 6 is small, it flows into the pressure tank 9.
The water level will rise. When the pressure detector 11 rises to the upper limit specified pressure (normal water supply pressure + 2 to 3 Kg/cm ² ), the control device 12 receives a signal from the pressure detector 11 and stops power supply to the variable speed motor 4, and turns off the water supply pump 5. stops.

While the water supply pump 5 is stopped, water is supplied from the pressure tank 9 through the water pipe 6. When the water level in the pressure tank 9 drops and the pressure drops to a specified value, the pressure detector 11 outputs a signal, which is sent to the control device 12, the variable speed motor 4 is started, and the water supply pump 5 is activated to open the water tank 1. Pump up and supply water.

According to the present invention, the water supply pump is not started or stopped frequently when the amount of water used is small, so power consumption is reduced. The pressure tank is small and the pump starts up infrequently. Therefore, the equipment cost,
Running costs are both low, and the number of times of starting and stopping is small, which has the effect of lengthening the life of equipment such as pumps and variable speed motors.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention. 1...Water tank, 2...Foot valve, 3...Water intake pipe, 4...Variable speed motor, 5...Water pump, 6
... Water pipe, 7 ... Flow switch, 8 ... Branch pipe, 9 ... Pressure tank, 11 ... Pressure detector, 1
2...control device.

Claims (1)

[Claims] 1 Water pipes that are fed by variable speed water pumps are equipped with flow rate detectors that detect the flow rate in the water pipes and pressure detectors that detect the pressure in the water pipes, and water pipes that are branched from the water pipes and equipped with pressure tanks. An operation in which the variable speed pump is stopped in an extremely small water flow region using a variable speed water supply pump device equipped with a water pipe system and a control device that receives signals from the flow rate detector and pressure detector and controls and drives the variable speed pump based on the signals. In this method, when the flow rate detector detects a flow rate below the minimum water flow rate and a certain period of time has elapsed, the control device temporarily increases the rotational speed of the variable speed motor before stopping the variable speed pump to maintain the specified water supply pressure. The invention is characterized in that the pressure detection value is set so as to operate at a higher pressure than the variable speed motor, and the water level pressure stored in the pressure tank is increased so that the variable speed motor is stopped via the control device, and then the variable speed motor is stopped. How to operate a variable speed pump.