JPS63631B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pump flow rate control device for supplying and circulating a required flow rate by a plurality of pump groups to a flow rate fluctuation circuit in which the required circulation flow rate (water amount) changes every moment, and further relates to More specifically, the present invention relates to a device that effectively suppresses internal disturbances in a control system due to rapid fluctuations in pressure and flow rate that occur when pumps are turned on when controlling the number of pumps arranged in parallel.

BACKGROUND ART Conventionally, a circuit as shown in FIG. 1 has been used as a system in which, for example, a large number of chilled water coils are installed in a building, and a refrigerator supplies and circulates the required amount of chilled water to the chilled water coils (loads). That is, in relatively large buildings, etc., a system is adopted in which chilled water from a plurality of parallel refrigerators 2 is circulated and supplied to a large number of chilled water coils 1 by a plurality of parallel pumps 3. In such a system, the amount of water entering the chilled water coil 1 of the load is adjusted by the valve 5 that receives a signal from the thermostat 4, so the total amount of water in the outgoing pipe 6 and return pipe 7 changes from moment to moment depending on the amount of load. Increase or decrease. However, if this required amount of water is to be met by controlling the number of pumps 3 arranged in parallel, there will be a stepwise change as the number of driven pumps increases or decreases. This step width can be reduced by arranging a large number of small-capacity pumps, but the number of pumps and the upper limit of their capacity are also limited due to the number of refrigerators installed (normally, two or more refrigerators are installed). 4 machines, correspondingly the number of pumps is often 2 to 4),
Step changes in pressure and flow rates are inevitable.

On the other hand, the amount of cold water in each of the refrigerators 2 is required to be always constant. In other words, the amount of water passing through each of the refrigerators 2 must be constant even with stepless changes in load. For this reason, a bypass pipe 10 is usually provided between the headers 8 and 9, and the remaining amount of water is circulated through this bypass pipe 10.
In order to determine the amount of bypass water, a bypass valve 11 installed in the bypass pipe 10 is controlled. The opening degree of the bypass valve 11 is controlled by adjusting a differential pressure signal detected by a differential pressure detector 12 using a pressure regulator 13. However, the bypass valve 1
If the opening degree of 1 is made to correspond moment by moment, this control circuit will not settle down, so it is necessary to operate the pressure regulator 13 by setting it so that it becomes dull with respect to small fluctuations in the amount of water. Therefore, when there is a sudden change such as when the pump is turned on, the bypass valve may not be able to immediately follow the opening to 100%, which may cause trouble. For example, the water cutoff relay attached to the refrigerator may become activated.

The present invention provides a device that effectively suppresses the problem of internal disturbance when pumps are turned on when trying to satisfy the required flow rate of such a flow rate variable system while controlling the number of pumps arranged in parallel. It was developed. That is, the present invention provides a water piping system in which the required flow rate of a flow rate fluctuation circuit is supplied and circulated by controlling the number of pumps arranged in parallel, which are inserted into this circuit via a header, and which is connected to an outgoing pipe and a return pipe of the circuit. In a water piping system, a bypass pipe is provided that communicates with the water pipe, and the opening degree of a bypass valve installed in the bypass pipe is controlled according to the differential pressure between the outgoing pipe side and the return pipe side.
In addition to the differential pressure control circuit that controls the opening of the bypass valve according to the differential pressure, there is also a flow buffer circuit that provides an opening signal to the bypass valve based on the ON signal of the pump. The bypass valve is configured to control the opening of the bypass valve based on an output signal from the buffer circuit, and the timing of controlling the opening of the bypass valve based on the output signal from the flow rate buffer circuit is when the ON signal of the pump is received. Provided is a pump flow rate control device for a flow rate fluctuation system, characterized in that the output signal is changed in a direction in which the opening degree of a bypass valve is gradually decreased within a predetermined time range from It is something to do.

The apparatus of the present invention will be explained below according to the embodiments shown in the drawings. FIG. 2 is an equipment layout system diagram of an apparatus of the present invention in which a flow buffer mechanism is incorporated into the conventional circuit shown in FIG. That is, the opening degree of the bypass valve 11 installed in the bypass pipe 10 shown in FIG. 1 can be controlled by inserting a control device as shown in FIG. 2. In FIG. 2, 12 is a differential pressure setting device similar to that shown in FIG. , this selector 16 has a solenoid valve 19 connected to a pressure setting device 18 operated by main air 17 as a signal medium.
are connected, and these solenoid valves 15 and 19 are activated by the ON signal of pump 3, and high selector 1
The signal selected at 6 controls the opening degree of the bypass valve 11. A throttling mechanism 20 is attached to the automatic valve 19 to prevent sudden pressure fluctuations from being applied to the water piping system due to the operation of the device of the present invention. Each of these control devices is
All of these devices use signals that are transmitted through the air. However, if the water piping system is small-scale, one that operates by electric signals may be used.

To describe the operation of each device, the solenoid valves 15 and 1
Each of the valves 9 is a three-way valve, and is an electromagnetically operated valve whose switching is performed by mediating air. The solenoid valve 15 sends the signal from the pressure regulator 13 to the bypass valve 11 via the high selector 16, but is switched to the atmosphere release side by the ON signal of the pump, and the differential pressure signal is released (disappeared). be. Under normal conditions, the solenoid valve 19 is switched to the throttling mechanism 20 so as to lose its signal transmission function, and upon receiving the pump ON signal, gives a signal to keep the opening of the bypass valve 11 at a constant value. After a predetermined period of time (10 to 30 seconds) has elapsed, it should be returned to its original state. The pressure setting device 18 determines the desired opening degree of the bypass valve 11 when the pump is turned on (this determination is important when controlling the number of pumps with different capacities) and sets the set value. decide. The throttling mechanism 20 provides a timer-operated throttling action that gradually dissipates the bias pressure (pressure from the pressure setting device 18) to prevent sudden fluctuations when switching from bias pressure to differential pressure signal pressure. When switching from bias pressure to differential pressure signal pressure, the high selector 16 compares the bias pressure that gradually decreases with the differential pressure signal pressure that gradually increases by the throttle mechanism 20, selects the higher one, and selects the higher one. This serves to prevent the opening degree of the valve 11 from changing rapidly.

FIG. 3 shows the operating circuit during normal operation, in which the solenoid valve 15 is in a state where a-b is open and c is closed, and the solenoid valve 19 is in a state where a-c is open and b is closed. Therefore, the signal from the pressure regulator 13 is utilized to control the opening degree of the bypass valve 11. Figure 4 shows the operating circuit when the pump ON signal is received, and the solenoid valves 15 and 15 are open, meaning that the signal (air signal) from the pressure regulator 13 is
At 5, it is released to the atmosphere through c and disappears, and the solenoid valve 19
When a-b is opened, a signal biased by the pressure setting device 18 is forcibly applied only during the timer operation, and the opening degree of the bypass valve 11 is set to a predetermined opening degree. When this timer expires, solenoid valves 15 and 18
returns to the state shown in FIG. 3, but the bias signal pressure gradually decreases due to the operation of the throttle mechanism 20.
At the same time, the differential pressure signal pressure also returns to normal. During this time, signals from both sources flow into the high selector 16, and the high selector 16 selects the higher pressure one of them and outputs it to the bypass valve.

In this way, even when the pump is turned on, it is possible to buffer the flow rate fluctuations per pump.
Smooth flow control is achieved even during the transition period up to normal operation. Therefore, the amount of cold water passing through the refrigerator 2 can be avoided from changing as in the conventional case due to pump input, and troubles such as water cutoff relay operation can be prevented.

[Brief explanation of the drawing]

FIG. 1 is an equipment layout system diagram of a conventional flow rate fluctuation circuit control device, FIG. 2 is an equipment layout system diagram showing control of a flow rate fluctuation circuit according to the present invention, and FIG. 3 is a circuit diagram showing the operating state of the control equipment part. 4 are circuit diagrams showing other operating states of the control equipment section. 1... Cold water coil, 2... Refrigerator, 3... Pump group, 8, 9... Header, 10... Bypass pipe line, 11... Bypass valve, 12... Differential pressure setting device,
13...Pressure regulator, 15...Solenoid valve, 16...
High selector, 17... Main air, 18...
Pressure setting device, 19... Solenoid valve, 20... Squeezing mechanism.

Claims (1)

[Scope of Claims] 1. A water piping system in which the required flow rate of a flow rate fluctuation circuit is supplied and circulated by controlling the number of pumps arranged in parallel, which are inserted into this circuit via a header, and which is connected to an outgoing pipe and a return pipe of the circuit. A bypass pipe line communicating with the pipe is provided,
In a water piping system in which the opening of a bypass valve installed in the bypass pipe is controlled according to the differential pressure between the outgoing pipe side and the return pipe side, the opening degree of the bypass valve is controlled according to the differential pressure. In addition to the differential pressure control circuit, a flow rate buffer circuit is provided that applies an opening signal to the bypass valve in response to the ON signal of the pump. The bypass valve is configured to control the opening of the bypass valve, and the timing of controlling the opening of the bypass valve by the output signal from the flow buffer circuit is set within a predetermined time range from the time when the pump ON signal is received, and within that predetermined time. 1. A pump flow rate control device for a flow rate fluctuation system, characterized in that the output signal is changed in the direction of gradually decreasing the opening degree of a bypass valve within a range.