Structural design and test method of the heart val

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Structural design and test method of heart valve of intelligent water meter

structural design and test method of heart valve of intelligent water meter:

it has been many years since the development of intelligent water meter. There are some quality and technical problems with intelligent water meters that have been put into use in the market for many years. These problems finally focus on the actuator composed of upper fixture, lower fixture, reducer, electric control system, DC Electromechanical, frame, lead screw, workbench and other parts. Developers have done experiments on the basic functions of actuators to verify the reliability of their functions in practical use. Why do the verified actuators have unexpected problems in the formal use of users? I think there are comprehensive problems in design structure, test method and test environment. The following is my personal view on the comprehensive issues of valves

I. structural design:

(I) structural design of valve:

1 Basic principle of valve operation

at present, the types of valves on the market include: electromagnetic pilot valve, motor pilot valve, motor ball valve, and flat stack valve

1). Working principle of the solenoid pilot valve: when the solenoid valve is opened, the pressure in the valve seal pressure chamber is relieved, the water pressure in the pipeline pushes the valve seal away, and the intelligent water meter works normally; When the solenoid valve is closed, the hole of the pressure relief chamber is closed. At this time, the water pressure in the chamber on the valve seal rises rapidly until the valve seal is pressed against the valve port and the water outlet is closed

2). The motor pilot valve adopts a reduction mechanism. In order to solve the sealing problem of moving parts, the moving rod adopts the magnetic drive principle to control the opening and closing of the pressure relief hole, so as to achieve the opening and closing of the valve seal. It is similar to the principle of electromagnetic pilot valve, but the time and reaction speed are slower than that of electromagnetic pilot valve. The problem is the same as that of the solenoid pilot valve

3). Working principle of motor ball valve: the speed of the motor is reduced by the reduction mechanism, and the torque is increased to drive the ball valve to rotate, so as to achieve the function of opening and closing. The manufacturing process requirements of the ball valve itself are relatively high, and the rotation force of the ball valve must have a very standard parameter, that is, the rotary ball valve must be controlled within the range of a set of process parameters. Moreover, the sealing of the driving ball operating rod is also a key, in which the O-shaped rubber ring is basically used for sealing, so the rubber ring is too tight will increase torque, and too loose will lead to loose sealing and leakage

4). Working principle of the plane stack valve: the speed of the motor is reduced by the reduction mechanism, and the torque is increased to drive the plane stack valve to rotate, so as to achieve the function of opening and closing. The tightness is guaranteed by water pressure. The planarity and smoothness requirements of the friction plane of the valve plate for the plane stacked valve are quite high, which is the classification and safety device of the shared electronic tensile testing machine, and there are also high requirements for the materials used. In order to solve these problems, the lower lamination of the plane laminated valve adopts ceramic substrate, and the upper lamination adopts other wear-resistant materials with high strength. It is completely manufactured and processed according to the principle of chemical mechanical seal, which not only ensures the reasonable contact surface, but also ensures the minimum friction coefficient

2. Structural analysis:

in the actual use of the solenoid pilot valve and motor pilot valve in the tap water pipeline, there have been problems such as the blockage of the pilot hole caused by the long-term water quality problem, and the valve stem being stuck due to the iron particles absorbed by the pressure relief valve stem. Through the use and feedback information of the market, the developer has learned that the actuator with this structure is not suitable for the current water quality use of the water department of our country. As a result, developers have turned to ball valves and flat stack valves. Now use more ball valves. The following is a comprehensive analysis of the structure of ball valve and plane stack valve:

1). Motor ball valve: in the structure of ball valve, improve the process level, and control the torque of ball valve within a certain range of torque parameters without leakage. This process requirement includes two requirements: first, the tightness between the ball valve and the sealing pressure, and then turn the purified syngas into methanol tight ring, which should not leak when closed under a certain pressure; And the torque used for rotation under external force is within a parameter range. This parameter value should be:

f f1+f2+f3

, where: F - torque output by motor driven reducer

f1 - torque force of ball rotation

f2 - torque of rubber seal of rotating rod

f3 - the acting force of pipeline dynamic water pressure on ball valve

at present, there are several switching times of motor ball valves in the market from 8 seconds to 14 seconds, among which motor ball valves with a structure of about 8 seconds and motor ball valves with a structure of about 14 seconds have been tested. The test environment is 1.0MPa, and the power supply mode is battery direct supply. The test uses new batteries. Test results:

8 seconds, it is difficult for the motor ball valve to close the valve in a dynamic environment of 0.6MPa, and sometimes it can't even close

14 seconds, the motor ball valve closed normally in the dynamic environment of 1.0MPa, and there was no valve closing error

according to the results of the two tests, we can see that torque is very important for ball valves. We assume that the motor has the same parameters, so if the specific speed of 8 seconds is 1, then the specific speed of 14 seconds is 1.75. Therefore, the key of the motor ball valve is the specific speed of the reduction mechanism, but the above-mentioned process problems are also very important

2). Flat stack valve: a valve developed on the basis of mechanical seal structure. The characteristic of the valve is horizontal, and the flow direction is from top to bottom. Therefore, the water pressure plays a great role in the upper valve plate when the valve is closed. The higher the pressure, the better the sealing performance. When working, the valve plate rotates in a plane. What needs to be overcome is the friction coefficient between the valve plates, and the influence of water pressure on it is not as great as that of ball valve. However, the friction of the upper lamination under strong water pressure should be overcome. The friction between laminations passed the actual test, and Jifu did not increase much force. The test is carried out on the same water meter and the following methods are followed:

⑴ connect the ammeter in series in the switch circuit and operate the valve opening and valve closing switches to control

⑵ IC card water meter is installed in the water pump pipeline with 105m head, and the pressure gauge and tee installation valve are connected in front of the water meter interface to adjust the pressure of water supply in the pipeline

⑶ when the water pump is turned on and the pressure is adjusted to about 1.0MPa, the operation test of opening and closing the valve is carried out

⑷ gradually adjust the pressure to 1.5MPa by adjusting the valve

the test is carried out in a dynamic environment, which is completely consistent with the actual use of industrial and mining. When the water pressure is 1.0MPa, the required current is: close the valve and start 50mA. When it is about to close, the current suddenly rises to about 110mA; Current when opening the valve: the current is about 110mA when opening the valve and starting. When the valve is opened, the current drops rapidly to 50mA

when the water pressure is 1.5MPa, the required current is: close the valve and start 55mA. When it is about to close, the current suddenly rises to about 120mA; Current when opening the valve: the current is about 120mA when opening the valve and starting. When the valve is opened, the current of water flowing out of the meter rapidly drops to 55mA

from the test results, the influence of water pressure on the laminated valve is very small, which reflects the change in current, that is, 5mA to 10mA. The water pressure increased by 50% from 1.0MPa to 1.5MPa; The current rises from 50mA to 55mA and from 110mA to 120mA, an increase of about 10%. Therefore, in the laminated valve, the influence of water pressure rise on the valve opening force is relatively small, and the relationship is 1:5. Of course, this must be based on specific materials and friction coefficients

The opening and closing time of the deceleration mechanism of the plane stack valve is 8 seconds and 14 seconds. The valve was tested for two times. The test environment was 1.0MPa, and the power supply mode was battery direct supply. The test uses new batteries. Test results:

8 seconds, the dynamic environment switch of the plane stack valve at 1.0MPa is normal

14 seconds, the dynamic environment switch of the plane stack valve at 1.5MPa is normal

3. Summary

from the test results and theoretical calculation results, we have known that the structure of the plane stack valve is more suitable for the actuator used in the intelligent water meter. In mountainous cities, the water supply pressure of the water department is higher than that of ordinary plain cities. At present, the water supply pressure of high-rise buildings in cities will also be higher than that of ordinary floors. Valves that have not been closely verified have lost their functions in high water pressure environments. Intelligent water meter is a modern high-tech product, which represents the development level of automatic instruments. As a developer, the development of intelligent water meter that can meet the requirements of users should be put in the first place, and the product should cover all the use environment

(II). Valve drive structure:

in the plane stacked valve structure, the current structure used for valve drive is:

1 The upright rod is added with double Buna-N O-ring to prevent water leakage

2. Strong magnetic drive is used up and down to prevent water leakage

in terms of structure, the magnetic drive method should be used for sealing, and the current sealing effect is still very good. However, the quality of tap water delivered to users by the water department of our country is not pure water. There are many impurities in the water, and there are also considerable iron containing substances in the impurities. Due to the water quality, in less than 6 years, the iron material in the water will be attracted by the strong magnetic field of the driving gear, and the gear will be tightly wrapped. Finally, the friction coefficient of the gear with strong magnetic field in the water will increase, and even the rotation hysteresis will appear. This situation has occurred many times on the motor pilot valve. Therefore, there are basically no products that still use motor pilot valves

vertical rod O-ring seal, it is impossible to seal the liquid with pressure, especially for IC card water meter, which is more difficult. First, the motor itself has small power and torque. If the O-ring is too tight, the friction coefficient will increase rapidly, and the switching valve current will increase; Second, too loose O-ring will cause sealing effect and easy to leak. If the processing is not tight or loose, the process requirements will be improved, which will lead to the rise of manufacturing costs. Even if the processing technology is very mature, the O-ring will deform under the pressure of water for a long time. Generally, the water pressure of water division will leak at the sealing place of the O-ring in about two years

a at present, the product quality of IC card water meters has become better and better. The quality problems are often caused by problems such as valve failure or leakage after installation and use for a year or two. If the valve is magnetically driven, it will fail to close and open the valve due to the increase of the friction coefficient for a longer time. How to solve the problem, I think: in the IC card water meter, it is not planned to adopt the structure of O-ring and magnetic drive. In the pressure pipe, the structure of mechanical seal should be adopted for the water seal, so as to seal for a long time, so as to ensure that there will be no water leakage in the six-year use, and ensure the realization of the valve function

b. At present, the quality problems found in the user's use are mainly water leakage, the valve cannot be completely closed, the valve loses its function, etc. The key to these quality problems is caused by the sealing structure adopted by the valve drive. If the sealing structure of the valve drive is improved, the water leakage problem and the technical problem that leads to the loss of the valve execution function can be completely solved

mechanical seal is a kind of dynamic seal, which is widely used in the chemical industry. Its sealing reliability is very good. In IC card water meter

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