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What is the positive transmission of gears

When the total displacement coefficient of a pair of gears is greater than 0, it is a positive transmission.
Positive transmission refers to the positive displacement design of the gear. If two gears meshing with each other are in positive displacement, their center distance is greater than (the pair of gears) standard center distance. Conversely, if both gears use negative displacement, the center distance is smaller than the standard center distance. To judge whether the position is shifted, it is mainly to compare the measured gear parameters (including center distance) with the standard parameters of the gear to draw a conclusion.
Gear transmission is the most widely used transmission form in mechanical transmission. It has relatively

accurate transmission, high efficiency, compact structure, reliable work and long life. At present, the achievable indexes of gear technology: peripheral speed v=300m/s, rotation speed n=105r/min, transmitted power P=105KW, modulus m=0.004~100mm, diameter d=1mm~152.3mm
Features
1, the instantaneous transmission ratio is constant. The instantaneous transmission ratio of non-circular gear transmission can be designed according to the required change law.
2, the transmission ratio range is large, which can be used to decelerate or increase speed.
3, the range of speed (pitch circle speed) and transmission power is wide, and it can be used for high-speed (v>40m/s), medium-speed and low-speed (v<25m/s) transmission; power is from less than 1W to 105KW.
4, high transmission efficiency. A pair of high-precision involute cylindrical gears has an efficiency of over 99%.
5, compact structure, suitable for short-distance transmission.
6, the manufacturing cost is higher. Certain gears with special tooth shapes or high precision require special or high-precision machine tools, cutting tools and measuring instruments, so the manufacturing process is complicated and the cost is high.
7, low-precision gears, noise, vibration and shock during transmission, pollute the environment.
8, no overload protection
According to the relative position of the two shafts and the direction of the gear teeth, it can be divided into the following types:
<1>Straight tooth cylindrical gear drive;
<2> Helical cylindrical gear drive
<3> herringbone gear transmission;
<4> bevel gear transmission;

bevel gear

bevel gear

<5> cross-axis helical gear transmission.
According to the working conditions of the gear, it can be divided into:
<1>; Open gear transmission type gear transmission, the gears are exposed, and good lubrication cannot be guaranteed.
<2>; half-open gear transmission, the gear is immersed in the oil pool, with a protective cover, but not closed.
<3>; closed gear transmission, gears, shafts and bearings are all installed in a closed box, with good lubrication conditions, difficult for dust and sand to enter, accurate installation,
Gear transmission has good working conditions and is the most widely used gear transmission.
Gear transmission can be classified according to the relative position of its axis.
Gear drive can be divided into cylindrical gear drive, bevel gear drive, non-circular gear drive, rack drive and worm drive according to the shape of the gear.
According to the tooth profile curve, it can be divided into involute gear transmission, cycloid gear transmission and arc gear transmission. A transmission composed of more than two gears is called a gear train. The gear transmission can be divided into ordinary gear transmission and planetary gear transmission according to whether there are gears with axis movement in the gear train. The gears with axis movement in the gear train are called planetary gears. Gear transmission can be divided into closed type according to its working conditions
Gear transmission calculation
Open and semi-open transmission. Sealing the transmission in a rigid case and ensuring good lubrication is called closed transmission, which is more commonly used, especially for higher-speed gear transmissions, which must be closed transmission. Open transmission is exposed and cannot guarantee good lubrication. It is only used for low speed or unimportant transmission. Half-open transmission is somewhere in between.
The law of meshing:  The smoothness of gear transmission requires the instantaneous transmission ratio in the process of gear tooth meshing i=angular speed of driving wheel/angular speed of driven wheel=ω1/ω2=constant, this requirement is guaranteed by tooth profile. Figure 2 shows that the two meshing tooth profiles E1 and E2 are in contact at any point K, and the common normal line N1N2 of the two tooth profiles is made through the point K, which intersects the connecting center line O1O2 at point C. The condition for maintaining contact during the meshing process of the two tooth profiles is that the velocity of the K point on the tooth profile E1, vK1, and the K point velocity on the tooth profile E2, vK2, are equal in the direction of the common normal line N1N2, that is, vKn1=vKn2=vKn. Make perpendicular lines from O1 and O2 to the N1N2 line and intersect at points N1 and N2. The above formula shows that the two-wheel tooth profile must meet the following conditions: “No matter where the two-wheel tooth profile is in contact at any position, the common normal line passing through the contact point must pass the fixed point C ─ ─ node on the connecting center line.” This is a circular gear. The basic law of tooth profile meshing. There are many curves that can meet this law. In fact, the requirements of manufacturing, installation and load-bearing capacity should be considered. Generally, only involute, cycloid and arc are used as the working tooth profile of the gear. Part of the tooth profile is involute.
For involute gears, the base radius rb1 and rb2 of wheel 1 and wheel 2 are respectively. The N1N2 line is the internal common tangent of the two base circles, that is, the common normal of any contact point of the two tooth profiles coincides with it. Because the two base circles have only one internal common tangent in one direction, the common normal of any contact point passes through the fixed point C, which shows that using an involute as the tooth profile conforms to the basic law of tooth profile meshing.
The two circles drawn through node C with O1 and O2 as the centers are called pitch circles. The pitch radius of wheel 1 and the pitch radius of wheel 2 Involute gears have the following characteristics: ①N1N2 is the trajectory of the contact points of the two tooth profiles, called the meshing line, which is a straight line. ②The common tangent line tt of the two pitch circles of gear transmission through node C is called the meshing angle α’between it and the meshing line N1N2, which is a constant. ③The pressure between the tooth surfaces is always along the direction of the common normal line N1N2 of the contact point, so the pressure direction between the tooth surfaces does not change when the involute gear transmits power. ④The transmission ratio is inversely proportional to the radius of the base circle of the two wheels. After the gear is made, the base circle is determined. Therefore, even if the center distance is slightly deviated from the design during operation, the transmission ratio will not be affected. This feature is called the separability of the transmission. It affects the processing, assembly and Maintenance is very beneficial. ⑤The two tooth profiles only have no sliding between the tooth surfaces when the node C is in contact, and there is sliding between the tooth surfaces when they are in contact at other points, and the farther away from the node, the greater the sliding. ⑥Since the involute gear can mesh with a rack with a linear tooth profile, it can be processed by a tool with a linear tooth profile. The tool is easy to manufacture and the machining accuracy can be high.
Coincidence degree: Coincidence degree is an important parameter that affects the continuous transmission of gears. As shown in Figure 2, gear tooth meshing starts from the contact between the tooth root of the driving wheel and the tooth tip of the driven wheel, that is, the intersection A of the tooth tip circle of the driven wheel and the meshing line is the starting point of meshing. As the wheel 1 rotates, the wheel 2 is pushed to rotate, and the contact point moves along the meshing line. When the contact point moves to the intersection E of the addendum circle of the wheel 1 and the meshing line (the dotted line in the figure), the tooth profile When the meshing ends, the two tooth profiles begin to separate. Point E is the meshing end point, which is the actual meshing line length. If the front pair of teeth are still in contact at point D before point E, and the latter pair of teeth are in contact at point A, then the transmission is continuous; if the front pair of teeth has left at point E, and the latter pair has not yet entered meshing , Then the transmission is interrupted. Considering the influence of gear manufacturing, installation errors and deformation, ε≥1.1~1.4 is often required in practice. The greater the coincidence degree, the more stable the transmission. The above refers to the coincidence degree of the end face of the cylindrical gear, and there is a longitudinal coincidence degree for the helical cylindrical gear.
The condition for a pair of gears to be able to mesh correctly is that they must have equal modulus and equal pressure angle.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news /knowledge:
what is Spur gear?
Types of mechanical transmission;
Common failures of butterfly valves and the characteristics of installation
Stainless steel valve material parameters and specific applications

What is the transmission ratio

In a mechanical transmission system, the ratio of the angular velocity or rotational speed of the driving wheel at the beginning and the driven wheel at the end.
Transmission ratio (i) = ratio of driving wheel speed (n1) to driven wheel speed (n2) = inverse ratio of gear index circle diameter = ratio of driven gear teeth (Z2) to driving gear teeth (Z1).
That is: i=n1/n2=D2/D1 i=n1/n2=z2/z1
For multi-stage gear transmission
1: The transmission ratio between every two shafts is calculated according to the above formula
2: The total transmission ratio from the first axis to the nth axis is calculated according to the following formula: Total transmission ratio ι=(Z2/Z1)×(Z4/Z3)×(Z6/Z5)……=(n1/n2)× (N3/n4)×(n5/n6)……

For multi-stage gear transmission

For multi-stage gear transmission

Extended information

The ratio of the angular velocities of the two rotating components in the mechanism is also called the speed ratio. The transmission ratio of component a and component b is Ⅰ=ωa/ωb=na/nb, where ωa and ωb are the angular velocities (radians/sec) of components a and b, respectively; na and nb are the rotational speeds of components a and b respectively ( Rpm) (Note: a and b after ω and n are subscripts).
When the angular velocity in the formula is an instantaneous value, the obtained transmission ratio is the instantaneous transmission ratio. When the angular velocity in the formula is an average value, the obtained transmission ratio is the average transmission ratio. For most gear transmissions and friction wheel transmissions with the correct tooth profile, the instantaneous transmission ratio is unchanged; for chain transmission and non-circular gear transmission, the instantaneous transmission ratio is variable.
For meshing transmission, the transmission ratio can be expressed by the number of teeth Za and Zb of wheel a and wheel b, i=Zb/Za; for friction transmission, the transmission ratio can be expressed by the radius Ra and Rb of wheel a and wheel b, i=Rb/Ra, At this time, the transmission ratio generally means the average transmission ratio.
In hydraulic transmission, the transmission ratio of the hydraulic transmission element generally refers to the ratio of the turbine speed S and the pump wheel speed B, that is, =S/B. Hydraulic transmission elements can also be combined with mechanical transmission elements (generally with various gear trains) to obtain various transmission ratios of different values ​​(see gear trains for gear train transmission ratios).

Types of mechanical transmission

There are many forms of mechanical transmission, which can be divided mainly into two categories:
1. Friction transmission that transmits power and motion by friction between parts, including belt transmission, rope transmission and friction wheel transmission. Friction transmission is easy to achieve stepless speed change, and it can mostly adapt to transmission occasions with large shaft spacing. Overload and slip can also play a role in buffering and protecting the transmission device. However, this type of transmission is generally not used in high-power applications and cannot guarantee accuracy. The transmission ratio.
2. The meshing transmission of power or movement by the meshing of the driving part and the driven part or the meshing of intermediate parts, including gear transmission, chain transmission, spiral transmission and harmonic transmission. The meshing transmission can be used in high-power applications with accurate transmission ratio, but generally requires higher manufacturing accuracy and installation accuracy.

According to the forms of force transmission, mechanical transmission can be divided into:

1 Friction drive.
2 Chain drive.
3 Gear drive.
4 Belt drive.
5 Turbo worm drive.
6 Ratchet drive.
7 Crankshaft connecting rod drive
8 Pneumatic transmission.
9 Hydraulic drive (hydraulic planer)
10 Universal joint drive
11 Wire rope drive (most widely used in elevators)
12 coupling drive
13 Spline transmission.
1. Features of belt drive
Including driving wheel, driven wheel and endless belt.
1) It is used in the situation where the two axes are parallel and the rotation direction is the same, which is called the concept of opening motion, center distance and wrap angle.
2) The belt type can be divided into three categories: flat belt, V belt and special belt according to the cross-sectional shape.
3) The focus of application is: calculation of transmission ratio, stress analysis and calculation of belt, and allowable power of a single V belt.
Advantages-suitable for transmission with a large center distance between two axles; the belt has good flexibility, can alleviate impact and absorb vibration; slip when overloaded to prevent damage to other parts; simple structure and low cost.
Because the belt is elastic and is driven by friction, it has a simple structure, stable transmission, low noise, and can buffer and absorb vibration. When overloaded, the belt will slip on the pulley and protect other parts from overload. It is suitable for center distance Advantages such as larger transmission.
But belt transmission also has many shortcomings. The main ones are: accurate transmission ratio cannot be guaranteed, transmission efficiency is low (approximately 0.90~0.94), belt service life is short, and it is not suitable for use in high temperature, flammable, oil and water situations.
2. Gear transmission
Classification: plane gear transmission, space gear transmission.
Features
Advantages-Wide range of applicable peripheral speed and power; accurate, stable, and high-efficiency transmission ratio; high reliability and long life; transmission between parallel shafts, intersecting shafts at any angle and intersecting shafts at any angle can be realized.
Disadvantages-requires higher manufacturing and installation accuracy, higher cost; not suitable for long-distance transmission between two shafts.
The names of the basic dimensions of involute standard gears include addendum circle, tooth root circle, index circle, touch number, pressure angle, etc.
1. The range of power and speed transmitted by the gear is very large, the power can be as small as hundreds of thousands of kilowatts, and the peripheral speed can be as small as more than one hundred meters per second. The gear size can range from less than 1mm to more than 10m.
2. Gear transmission belongs to meshing transmission, the gear tooth profile is a specific curve, the instantaneous transmission ratio is constant, and the transmission is stable and reliable.
3. High gear transmission efficiency and long service life.
4. There are many kinds of gears, which can meet the needs of various transmission forms.
5. The manufacturing and installation of gears require high precision.
4. Features of chain drive
1) To ensure a more accurate transmission ratio (compared with belt transmission)
2) Power can be transmitted when the center distance between the two shafts is far (compared to gear transmission)
3) Can only be used for transmission between parallel shafts
4) After the chain wears out, the chain links become longer, which is easy to cause chain disconnection.
5. Worm gear drive
It is suitable for movement and dynamics between two axes that are vertical and not intersecting in space.
Features
Advantages-large transmission ratio. ; Compact structure size.
Disadvantages-large axial force, easy to heat, low efficiency; only one-way transmission.
The main parameters of the worm gear drive are: modulus, pressure angle, worm gear index circle, worm index circle, lead, number of worm gear teeth, number of worm heads, transmission ratio, etc.
Single-stage transmission can obtain a large transmission ratio, compact structure, smooth transmission, no noise, but low transmission efficiency. Two-stage transmission solves the shortcomings of single-stage transmission.
6. The characteristics of spiral transmission: high transmission accuracy, stable operation, no noise, easy to self-lock, and can transmit greater power.

In the valve industry, there are many ways to open and close the valve plate. we call it valve drive method. as below:

Unit two, valve drive mode (code name):

drive mode Electro-magne-tism Electro-magnetic hydraulic Electro-hydraulic tur-bine Spur gear Bevel gear pneu-matic Hydr-aulic Gas-hydr-aulic elec-tric han-dle Hand-wheel
code 0 1 2 3 4 5 6 7 8 9

See the link for more details: https://www.tanghaivalve.com/valve-model-establishment-and-meaning/

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news/knowledge:
What is the transmission ratio
What is the positive transmission of gears
Form and types of Gear transmission
Stainless steel valve material parameters and specific applications

Form and types of Gear transmission

Gear transmission types:

As per the mutual position of the two wheel axes, gear transmission can be divided into plane gear transmission and space gear transmission.
According to the type of gear transmission:

BS5163-BB-NRS-soft seated-wedge gate valve-DN700-PN16-bevel gear (8)

BS5163-BB-NRS-soft seated-wedge gate valve-DN700-PN16-bevel gear (8)

1. According to the relative position of the two shafts and the direction of the gear teeth, it can be divided into the following types:
<1>Cylinder gear drive;
<2>Bevel gear transmission;
<3> Cross-axis helical gear transmission.
2. According to the working conditions of the gear, it can be divided into:
<1> Open gear transmission, the gears are exposed, and good lubrication cannot be guaranteed;
<2>Half-open gear transmission, the gear is immersed in the oil pool, with a protective cover, but not closed;
<3> Closed gear transmission, gears, shafts and bearings are all installed in a closed box, with good lubrication conditions, difficult to enter dust, accurate installation, gear transmission with good working conditions, and it is the most widely used gear transmission.
3. According to the hardness of the tooth surface:
<1>Soft tooth surface gear The hardness of the tooth working surface is less than or equal to 350HBS or 38HRC;
<2>Hard tooth surface gear The hardness of the tooth working surface is greater than 350HBS or 38HRC. When a pair of gears are driven.

The form of gear transmission:
1. Parallel shaft gear (cylindrical gear)
(1) Spur gear: A straight cylindrical gear with tooth ribs parallel to the axis.
(2) Rack (Rack): A linear gear that meshes with a spur gear. It can be said to be a special situation when the pitch of the gear becomes infinite.
(3) Internal gear: The inner gear of a straight cylinder that meshes with the spur gear.
(4) Helical gear: Cylindrical gears with helicoid teeth.
(5) Helical rack: a linear gear that meshes with a helical gear.
(6) Double helical gear: a helical gear formed by left and right spiral tooth ribs.

2. Right-angle shaft gear (bevel gear)
(1) Straight bevel gear: A bevel gear whose tooth ribs are consistent with the generatrix (straight line) of the pitch cone.
(2) Spiral bevel gear: A bevel gear with a bevel line with a spiral angle.
(3) Zero helical bevel gear (Zerol bevel gear): a bevel gear with zero helix angle.

3. Gears with staggered shafts (worm gear and worm)
(1) Cylindrical worm gear: Cylindrical worm gear is the general name of worm (Worm) and gear (Wheel).
(2) Staggered helical gear (screw gear): This is a cylindrical helical gear, which is called when it is used for transmission between staggered shafts (also known as skew shafts).
(3) Other special gears: Face gear: a disc-shaped face gear that can mesh with a spur gear or a helical gear. Concave worm gear: Concave worm gear and its meshing gear. Hypoid gear: Conical gear that conveys the wrong axis. The shape is similar to a curved bevel gear.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news/knowledge:
What is the positive transmission of gears
Types of mechanical transmission
Stainless steel valve material parameters and specific applications

Comparison of pneumatic actuator, electric actuator and hydraulic actuator

The valve actuators used in the regulating valve are nothing more than pneumatic, electric and hydraulic:

hydraulic actuator for marine valve

hydraulic actuator for marine valve

1. Nowadays, most of the actuators used in industrial control places are because they use air source as power, which is more economical than electric and hydraulic, and has a simple structure, which is easy to control and maintain. From a maintenance point of view, it is easier to operate and proofread than other types of actuators, and it is also easy to realize the call of positive and negative on the spot. Its biggest advantage is safety. When using a locator, it is ideal for flammable and explosive environments. If the electrical signal is not explosion-proof or intrinsically safe, there is a potential risk of fire caused by ignition. Therefore, although the application range of electric control valves is becoming wider and wider, in the chemical industry, pneumatic control valves still occupy an absolute advantage.

2. Electric actuators: Electric actuators are mainly used in power plants or nuclear power plants, because the high-pressure water system requires a smooth, stable and slow process. The main advantages of electric actuators are high stability and constant thrust applied by users. The maximum thrust generated by the actuator can be as high as 225000kgf. Only hydraulic actuators can achieve such a large thrust, but the cost of hydraulic actuators is higher than that of electric Much higher. The anti-deviation ability of the electric actuator is very good, and the output thrust moment is basically constant, which can well overcome the unbalanced force of the medium and achieve accurate control of the process parameters, so the control accuracy is higher than that of the pneumatic actuator . If equipped with a servo amplifier, the positive and negative effects can be exchanged easily, and the signal-off valve position state (hold/full open/full close) can be easily set, and it must remain in the original position when it fails. What the pneumatic actuator cannot do, the pneumatic actuator must rely on a set of combined protection system to achieve position retention.

Hydraulic actuator: When we need abnormal anti-deflection ability, high thrust and fast formation speed, we often choose hydraulic or electro-hydraulic actuator. Because of the incompressibility of hydraulics, the advantage of using hydraulic actuators is better anti-deviation ability, which is very important for regulating conditions, because when the regulating element is close to the valve seat, the throttle condition is unstable. The larger the pressure difference, the worse this situation is. In addition, the hydraulic actuator runs very smoothly and responds quickly, so high-precision control can be achieved. The electro-hydraulic actuator integrates the motor, the oil pump, and the electro-hydraulic servo valve. It can work as long as it is connected to the power supply and the control signal. The hydraulic actuator is similar to the cylinder, but it can withstand higher pressure than the cylinder. Work requires an external hydraulic system. The factory needs to be equipped with hydraulic stations and oil pipelines. In contrast, electro-hydraulic actuators are more convenient.

Valve actuator / actuation -(8)- application areas

Application areas of valve actuators:
Electric actuators are mainly used in the following three areas:
1. Power plant
Typical applications are:
① Application in thermal power industry
Air blower damper damper, Primary air intake damper, Air preheat damper damper, Flue gas recirculation, Bypass

electric actuator for butterfly valve

electric actuator for butterfly valve

damper damper, Secondary air intake damper, Main bellows damper damper, Burner adjustment lever, Burner swing drive, Hydraulic push rod drive, Impeller Machine speed control, flue gas control valve steam, control valve, ball valve and butterfly valve, control sliding gate
②Valve actuator applications in other power industries
Ball valve dust control water jet impeller speed control control large hydraulic valve gas control valve burner ignition start steam control valve condensate recirculation, deaerator, boiler feed water, superheat controller, reheat thermostat controller, and other related valve applications
2. Process control
Used in the production process control of chemical, petrochemical, mold, food, medicine, packaging and other industries, according to established logic instructions or computer programs to accurately position, start and stop valves, tools, pipes, baffles, chutes, platforms, etc. , Opening and closing, rotation, use the temperature, pressure, flow, size, radiation, brightness, chromaticity, roughness, density and other real-time parameters detected by the system to adjust the system to realize the control of intermittent, continuous and cyclic processing .
3. Industrial automation
It is used in a wide range of aviation, aerospace, military, machinery, metallurgy, mining, transportation, building materials, etc., to adjust and control the movement points (moving parts) of various automation equipment and systems.
Examples of main applications in process control and industrial automation are as follows:
① Application in the production of sulphur ore
Water injection flow control ball valve and butterfly valve control
②Application of Potassium Carbonate Pipeline Valve Actuator
Sliding gate diverter Gate ball valve and butterfly valve Ball control valve
③Application of water treatment valve actuator
Liquid flow control, pressure regulator pressure control, acid solution flow control
④Application of valve actuator in limestone/cement plant
Ball or butterfly valve controls the treatment of dry cement, gypsum, or liquid. Air supply and induced draft fan adjustable damper damper bypass damper damper Environmental pollution control and dust removal device sliding door to control the logistics of raw materials in hoppers and storage gates control raw materials in The gas control valve at the feed port adjusts the intake air volume of the burner on the converter. The steam control valve controls the steam required for the production process.
⑤Application of actuators in grain processing plants
Gate Diverter valve Distributor Material unloader/heater Dust removal isolation baffle Air flow control (logistics drying) Ball valve and butterfly valve control
⑥Application of damper and valve actuator in steel mill
Ball or butterfly valve controls, the control of cooling water, wastewater, or other cooling media. Adjustable damper baffle air supply and induced draft fan bypass damper damper, gate Environmental pollution control and dust removal device, Sliding door controls, the flow of raw materials at the inlet to the hopper ,The raw materials in the storage warehouse are subject to logistics control, gas control valve, steam control valve, adjustment of the burner on the converter, and control of the steam required for the production process
⑦The application of damper and valve actuator in aluminum factory
Air blower damper damper, Primary air intake damper, Air preheat damper damper, Flue gas recirculation, Bypass damper damper, Secondary air intake damper, Main bellows damper damper, Burner adjustment lever, Burner swing drive, Hydraulic push rod drive, Impeller Machine speed control flue gas control, valve steam, control valve ball valve, and butterfly valve control, sliding gate
⑧Application of process control baffle
Air replenishment Exhaust fan bypass Hot/cold air mixing Emergency shutdown
⑨Application in petroleum industry
Oil injection process flow control Gas lift pipeline main valve pressure control Water injection process flow control Oil well oil quality sampling test / production valve
⑩Application in natural gas production and transportation industry
Gas lift airflow flow control, Gas pipeline main valve pressure control, Compressor surge control, Natural gas pressure control, Natural gas pipeline main valve pressure control, Emergency shutdown, Natural gas pressure regulator control, Pressure control, Compressor surge control, Flow control

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news/knowledge:
Notes on selection and installation of butterfly valve;
Valve actuator / actuation -(1)-introduction;
Valve installation instructions and process precautions;
Working principle of electric gate valve

Valve actuator / actuation -(7)- generator

Generator for valve actuator:
1. The development history of generator controller The automatic control of generator set has experienced relay control. Greatly simplified the control circuit? Reliability has also been improved, to the point of more humanity,

electric actuator for butterfly valve

electric actuator for butterfly valve

there are also some generator manufacturers produce small gasoline engine integrated machine, practical and convenient.

2. Diesel generator set structure Diesel generator set is generally composed of three parts: engine, generator and controller. The generator powered by the engine converts the mechanical energy of the engine into electrical energy. The controller is the brain part of the generator set. It not only provides engine start-up, shutdown, data measurement, data display and fault protection functions, but also provides generator power measurement, power display and power protection functions.

3. (i.e. only provide start-up, shutdown and high water temperature, low oil pressure, overspeed protection? Does not provide power display? Water temperature meter, oil pressure meter, hour meter, battery voltmeter, AC voltmeter, AC Ammeter and other instruments), standard type (providing power display, providing protection function? Without communication interface), high-end type (in addition to providing standard functions, but also providing communication interface? Remote control, remote measurement, remote signaling functions are available, some It also has a network interface? It can be monitored through the Internet? Some have a text message function, which is more suitable for unattended computer rooms in remote areas).

Fourth, the inspection steps of the diesel generator set test machine when purchasing diesel generator sets? The customer is most concerned about the price of the generator set? There are many kinds of generator sets according to the brand? And the price of the generator set with different diesel engine power is different , Diesel generator set manufacturers will introduce to you how to compare the prices of diesel generator sets.

One question: Ask about the purchase time of the old diesel engine, ask about the repairs in the past? Which main parts have been replaced? Ask what are the problems in use? In order to have a more comprehensive and systematic understanding of the old diesel engine.

Second look: look at the signs and appearance of the old diesel engine. See which factory produced it? When did it leave the factory? How long did it take? See if the paint on the exterior is peeling off? Is there any defect? Whether the model is eliminated, etc. Judge the degree of newness of the old diesel engine from the label and appearance.

Three trials: Test machine. Check the old diesel engine carefully by shaking the crankshaft, turning the flywheel, starting the machine, etc. Test machine is a very important step? The specific inspection steps are as follows:

1. Rotate the crankshaft to supply oil from the fuel injector. If the fuel injector makes a crisp sound? It means that the performance of the fuel injector and plunger pair is still good. If there is no abnormal noise such as “whipping” in the wheel chamber, it means that the gear wear is not serious.

2. Pull up and down to fly, if there is no noise, it means that the gap between the crankshaft main shaft and the bearing bush is not large.

3. Turn the flywheel so that the piston approaches the bottom dead center? Then shake the flywheel left and right? If there is no “click” sound, it means that the wear between the connecting rod shaft and the bushing is not serious.

4. Decompress the cylinder and sway the crankshaft. When decompression is removed, if the rebound force of the piston is large, the flywheel rotates rapidly, indicating that the degree of wear of the cylinder, piston, and piston ring is small. When cranking the crankshaft, the pointer of the oil pressure gauge should be no less than 1 or the red mark of the oil instruction can rise quickly, and the hand pressure should be laborious.

5. Start the machine, if it is easy to start? The smoke is colorless or light gray? The speed is stable and no noise? It shows that the technical condition of the old diesel engine is good. Remarks: During the testing process of diesel generator set, it is best to operate and track changes in data such as air pressure and oil pressure in the diesel generator controller. Therefore, the stability of the quality of the diesel generator controller has high requirements in terms of humanization and other aspects. This controller is highly evaluated in the market.

6. How to buy diesel generator sets What issues should companies pay attention to when purchasing diesel generator sets? Diesel generator sets are widely used in telecommunications, financial and financial departments, hospitals, schools, commerce and other departments, industrial and mining enterprises and other special purpose independent power supply. Enterprises must have their own standards when purchasing diesel generator sets.

1. The performance and quality of the diesel generator set to be purchased must meet the requirements of relevant standards. The diesel generator set for communication must meet the requirements of the G3 or G4 level in GB2820-1997? At the same time as the “Communication diesel generator set into the network The 24 performance index requirements stipulated in the Implementation Rules for Quality Certification and Testing? At the same time, it must pass the strict inspection of the Communication Power Equipment Quality Supervision and Inspection Center established by the Chinese industry authority. The purchase of diesel generator sets for military communications must meet the relevant GB2820-1997, GJB related standards and the provisions of the “Quality Inspection Standards for Communication Power Equipment” formulated by relevant military departments, and must pass the strict inspection of the equipment quality by the organization department.
2. The main factors that should be considered when purchasing diesel generator sets. The main factors that should be considered when purchasing diesel generator sets are mechanical and electrical performance, the purpose of the unit, the capacity and range of load changes, and automation functions.

1. The purpose of diesel generator set. Because diesel generator sets can be used in three situations: common use, standby and emergency. Therefore, different applications have different requirements for diesel generator sets.
2. Load capacity of diesel generator set. The load capacity and load variation range should be selected according to different uses. Determine the single engine capacity of the diesel generator set and the capacity of the standby diesel generator set.
3. Environmental conditions for the use of diesel generator sets. Mainly refers to altitude and climatic conditions.
4. Selection of diesel generator set
5. Pay attention to generator and excitation mode when purchasing diesel generator set
6. Selection of the automation function of diesel generator set

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news/knowledge:
Valve actuator / actuation -(6)-Control panel;
Valve actuator / actuation -(2)-classification and working principle;
What is machining accuracy, machining error, tolerance?
Installation requirements for manual butterfly valves

Valve actuator / actuation -(6)-Control panel

Control panel of valve actuator:
The main purpose of the control panel is to distribute the electrical energy output by the generator to the user’s load or electrical equipment, and it is also used to indicate the operation of the diesel generator and to keep the

electric actuator for valve

electric actuator for valve

generator’s voltage stable when the load changes. Generally, voltmeters, frequency meters, ammeters, power meters, three-phase current conversion switches, three-phase voltage conversion switches, voltage setting knobs and various indicators are installed on the control panel. For the oil pressure gauge, oil temperature gauge, battery charging ammeter, water temperature gauge, start button and starter electric lock, some of them are directly installed on the control panel according to the design requirements, and some are installed on the dashboard of the diesel engine. The components installed inside the control panel are mainly related to the excitation mode of the generator and the automatic control of the diesel engine. The internal structure of the diesel generator set control panel.

Simple control panels are generally equipped with voltage regulators, silicon rectifier diodes, varistors, automatic air switches, current transformers and other components. More complex control panels must also install overload and short-circuit protection devices, electronic speed regulators, and other components. SCRs, relays, various safety devices and electrical equipment such as small transformers.

TH Valve is a professional manufacturer of butterfly valvegate valvecheck valveglobe valveknife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Related news/knowledge:
Valve actuator / actuation -(7)- generator;
Valve actuator / actuation -(1)-introduction;
Valve actuator / actuation -(2)-classification and working principle;
Working principle of electric gate valve

Valve actuator / actuation -(3)-classifications

Double acting valve actuator:
The selection of double-acting actuators takes DA series pneumatic actuators as an example. The output torque of

Pneumatic actuator (2)

Pneumatic actuator (2)

the gear-and-pinion actuator is the piston pressure (supplied by the air source pressure) multiplied by the pitch circle radius (arm). And the friction resistance is small and the efficiency is high. The output torque is linear when rotating clockwise and counterclockwise. Under normal operating conditions, the recommended safety factor for double-acting actuators is 25-50%

Single-acting valve actuator:
The selection of single-acting actuator takes the SR series pneumatic actuator as an example. In the application of spring return, the output torque is obtained during two different operations. According to the stroke position, each operation produces two different torque values. The output torque of the spring-return actuator is obtained by multiplying the force (air pressure or spring force) by the force arm. The first situation: the output torque is obtained by air pressure entering the central cavity to compress the spring, which is called “air stroke output torque”. In this case, the air source pressure forces the piston to turn from 0 degrees to 90 degrees. Due to the reaction force generated by the compression of the spring, the torque gradually decreases from the maximum value

hydraulic actuator for marine valve

hydraulic actuator for marine valve

at the starting point to the second condition: the output torque is the spring recovery when the middle cavity loses air. The force acting on the piston is called “spring stroke output torque”. In this case, due to the extension of the spring, the output torque gradually decreases from 90 degrees to 0 degrees. As mentioned above, the single-acting actuator is based on two It is designed on the basis of generating a balance torque under this condition.

Linear valve actuator:
1. Through single seat valve

The so-called single seat means that there is only one valve core and one valve seat in the valve body. Its characteristics are simple structure, small leakage (even completely cut off) and small allowable pressure difference. Therefore, it is suitable for occasions requiring clean media with small leakage and small working pressure difference. Special attention should be paid to the allowable pressure difference in the application to prevent the valve from closing.

2. Straight through double seat valve

There are two valve cores and valve seats in the valve body of the straight-through double-seat regulating valve. Compared with the single seat valve of the same caliber, its flow capacity is about 20% to 25% larger. Because the force of the fluid on the upper and lower valve cores can cancel each other, but the upper and lower valve cores are not easy to close at the same time, the double seat valve has the characteristics of large allowable pressure difference and large leakage. Therefore, it is suitable for clean media where the pressure difference between the two ends of the valve is large and the leakage requirement is not high. It is not suitable for high viscosity and fiber-containing occasions.

3. Angle valve

The valve body of the angle control valve is right-angled, its flow path is simple, and the service force is small. It is suitable for the control of high pressure difference, high viscosity, suspended solids and granular materials. Generally used for bottom inlet and side outlet, this kind of control valve has better stability. In high pressure situations, in order to prolong the service life of the spool, the side inlet and the bottom outlet can be used, but oscillation is prone to occur in small openings.

Valve actuator / actuation -(2)-classification and working principle

Classification of valve actuators:
(1) According to the driving energy used, the actuator is divided into three types: pneumatic, electric and hydraulic actuators.
(2) According to the form of output displacement, the actuator has two types: angle type and linear type.

Pneumatic actuator (2)

Pneumatic actuator (2)

(3) According to the law of action, actuators can be divided into three types: switch type, integral type and proportional type.
(4) According to the input control signal, the actuator can be divided into several types, such as air pressure signal, direct current signal, electric contact on-off signal, pulse signal, etc.

The working principle of valve actuator:
In the gear stage, the engine speed can be transmitted to the output rod through two sets of gears. The main reducer is completed by planetary gears, and the auxiliary reducer is realized by worm gears, which are fixed in the center by a set of tight springs. In the event of an overload, that is, when the output rod exceeds the set torque of the spring, the central worm gear will undergo axial displacement, and the switches and

electric actuator for valve

electric actuator for valve

signal devices will be fine-tuned to provide protection for the system. The output rod is coupled with the worm gear when the engine is working, and is coupled with the hand wheel when it is manually operated, under the action of the coupling operated by the external change control lever. When the engine is not working, the motor drive can be easily cut off, and the handwheel can be connected by simply pressing the lever. Since the motor drive takes

precedence over manual operation, when the engine restarts, the reverse action will automatically occur. This can avoid turning on the hand wheel when the engine is running, which is beneficial to protect the system.

Since the hand wheel is directly coupled with the output rod, it can ensure the normal manual operation of the valve when the internal gear fails or is damaged.

The switch and signal device installed on the gear is a sealed shell, which protects its internal components to achieve

hydraulic actuator for marine valve

hydraulic actuator for marine valve

the following functions:

  • Local or remote display of valve position
  • Actuator/valve overload protection
  • Limit valve stroke range
  • Electrical interface

The installation of valve actuators on different types of valves is completed by the output rod, which can be applied to various existing valve rod configurations.