Patent Publication Number: US-2010108293-A1

Title: High precision automatiac flow balancing device

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to the field of the circulating water control of central air-conditioning system, and in particular to an automatic flow balancing device for pipeline. 
     In the central air-conditioning system or heating apparatus, the energy loss due to the hydraulic disorder of circulating water system is very serious. Because the cooling fins or the terminal devices of the central air-conditioning system are arranged in the building at different distances away, the different resistances in the pipelines cause that the flow in some pipeline loops is excessive while the flow in some pipeline loops is insufficient, uneven thermal distribution thus occurs. Though the method of the reverse-return arrangement may be used, the cost of pipeline is too high and the energy consumption of water pump is increased due to the increase of flow path in this system. Furthermore, the reverse-return arrangement in the system can not completely solve the problem of hydraulic disorder. Sometimes, in order to cater for the flow demand at the worst position in the system, the flow has to be increased, and this results in a waste of energy when the system is in the condition of low load. Therefore, the flow balancing of pipelines is necessary for the energy conservation of the system. 
     At present, there are two kinds of flow balancing devices one of which is a self-operating balance device and the other of which is a manual balance device. 
     The self-operating balance device is based on mechanical self-operation principle, and basically a mechanical spring self-operating pressure differential device is used to automatically control the pressure difference of the through hole of the flow valve element to be constant, by determining the pressure difference between two sides of the flow valve. This balance device has a simple structure, but high conformity of the spring is required since the modulus of elasticity of the spring can directly affect the stability of pressure difference control, or else the conformity of pressure balance can not be guaranteed, and the precision of flow control is low. Furthermore, the through hole of the flow valve element may be stuffed by the impurity carried in the circulating water, and the spring may become aging due to directly contact with the circulating water. 
     The manual balance device utilizes instruments to balance the pressure difference between two sides of the flow balancing valve. According to the characteristic curve of relationship between the pressure difference and the flow, the pressure difference on two sides of the flow balancing valve is adjusted by regulating the opening degree of the valve so as to obtain the corresponding value of flow as desired. The manual balance device requires that each flow valve should be regulated manually one by one on the mounting spot, which requires special tools and specific person to perform the regulation. The workload is heavy. Though the precision of flow control is high, the flow balancing level of the circulating water in the entire central air-conditioning system can not be determined. 
     SUMMARY OF THE INVENTION 
     Having the state of the prior art and its attendant shortages, it is an objective of the present invention to provide a high precision automatic flow balancing device which can be set easily and control the flow in a precise manner. 
     To achieve the above objective, the technical solution of the present invention is as follows: A high precision automatic flow balancing device comprises a flow balancing valve controlled by an electric actuator and provided in each pipeline; a flow sensor provided in the each pipeline and connected to a control terminal; wherein the control terminal receives a flow signal of the flow sensor in the each pipeline and compares a preset value with the flow signal and then gives a control signal to the electric actuator so as to control the flow balancing valve to adjust the flow of the pipeline, forming a closed control loop. 
     The signal of flow in the pipeline is detected by the flow sensor continuously and then transmitted to the control terminal to be compared with the preset flow value, and a control signal is then outputted to the electric actuator to control the opening degree of the flow balancing valve to enable the flow in the pipeline loop to meet the requirement of the preset value. Flow sensors are respectively mounted in the pipelines of the circulating water system, and high-precision flow control can be obtained by the water distribution setting and regulating of the control terminal. The manual regulation on the spot is thus not necessary, and the workload is reduced accordingly. 
     Preferably, the control terminal may be connected to a network module. It is thus possible for remote setting and monitoring via network, and realizes the visible remote detecting and regulating of the flow in the pipeline network system, which further improves the automation level of the operation. 
     Preferably, the control terminal may be provided with an interface for connecting with the controller of water pump in the pipeline network. In the situation that the flow balancing valve in the specific pipeline loop is completely opened, the control terminal can output a signal to the pump controller to regulate the rotate speed of the water pump and thus regulate the flow. The way for hydraulic regulation is increased accordingly. 
     The flow sensor may be a mechanical flow sensor, an electromagnetic flow sensor, a vortex flow sensor or a supersonic flow sensor. The electric actuator has a linear actuator or a rotary actuator. The flow balancing valve may be a regulating valve or a ball valve. Proper components are selected according to the specific design requirement of different loop. 
     The present invention has the following advantages: convenient in the setting of device, easy regulation of the flow, high precision, available in the remote setting and monitoring, good monitoring of the whole pipeline network of the circulating water system, easy regulation of a specific loop, and high automation level. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of the connection of the parts of an embodiment of the present invention. 
         1 . Flow balancing valve; 
         2 . Electric actuator; 
         3 . Flow balancing valve; 
         4 . Electric actuator; 
         5 . Flow sensor; 
         6 . Flow sensor; 
         7 . Control terminal; 
         8 . Network module; 
         9 . Water pump. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Many aspects of the invention can be better understood in the following embodiments with reference to the accompanying drawings. 
     Referring to  FIG. 1 , a high precision automatic flow balancing device for use in the circulating system of the central air-conditioning system comprises flow balancing valves  1 ,  3  respectively controlled by electric actuators  2 ,  4  and respectively provided in two circulating pipelines; flow sensors  5 ,  6  connected to a control terminal  7  are respectively provided in the two pipelines; wherein the control terminal  7  receives the real-time flow signal from the flow sensors  5 ,  6  on the pipelines and compares preset values with the flow signals and then gives control signals to the electric actuators  2 ,  4  so as to control the flow balancing valves  1 ,  3  to regulate the flow of the pipeline, forming closed control loops. 
     The control terminal  7  is connected to a network module  5 . It is thus possible for remote setting and monitoring via network. The control terminal  7  is provided with an interface for connecting to the water pump controller of the pipeline network. In the situation that the flow balancing valve in a specific pipeline loop is completely opened, the control terminal can output a signal to the pump controller to regulate the rotate speed of the water pump  6  and thus regulate the flow. The way for hydraulic regulation is increased accordingly. 
     The signal of flow in the pipeline is detected by the flow sensor continuously and then transmitted to the control terminal to be compared with the preset flow value, and a control signal is then outputted to the electric actuator to control the opening degree of the flow balancing valve to enable the flow in the pipeline loop to meet the requirement of the preset value. Flow sensors are respectively mounted in the pipelines of the circulating water system, and high-precision flow control can be obtained by the water distribution setting and regulating of the control terminal. The manual regulation on the spot is thus not necessary, and the workload is reduced accordingly. 
     The flow sensor may be a mechanical flow sensor, an electromagnetic flow sensor, a vortex flow sensor or a supersonic flow sensor. The electric actuator has a linear actuator or a rotary actuator. The flow balancing valve may be a regulating valve or a ball valve. Proper components are selected according to the specific design requirement of different loop. 
     It should be emphasized that the above-described embodiments of the present invention, particularly, any preferred embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiment(s) of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.