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Harmonic drive vs planetary gear

In the late 1950s, American engineer C.W. Musser presented a unique insight that surprised gear-driven experts. He introduces a flexible gear into the gear drive, and the flexible gear deforms like a wave while the gear is running.

The planetary reducer is an industrial product. The planetary reducer is a communication mechanism whose structure is tightly coupled to the gear case by an internal ring. The center of the ring has a sun gear driven by external power. There is a set of planetary gear sets which are equally divided into three trays on the pallet. The planetary gears are floated during the period by the output shaft, the inner ring gear and the sun tooth support; when the input side power drives the sun teeth, It can drive the planetary gear to rotate and follow the trajectory of the inner ring to revolve along the center. The rotation of the planet drives the power output from the output shaft of the pallet. The speed converter of the gear is used to decelerate the number of revolutions of the motor (motor) to the required number of revolutions, and to obtain a mechanism with a large torque. In a reducer mechanism for transmitting power and motion, a planetary reducer is a precision reducer such as a Bapman planetary reducer or the like.
The harmonic reducer is mainly composed of three basic components: a wave generator, a flexible gear and a rigid gear. The harmonic drive reducer is a wave generator that produces a controllable elastic deformation of the flexible gear and meshes with the rigid gear. Gear transmission that transmits motion and power.

The working principle of planetary reducer and harmonic reducer is different, the transmission mode is also different, and the application industry is also different.

harmonic drive vs planetary gear

Planetary geared motor: The planetary reducer is also a planetary gear reducer. The gear structure is composed of a sun gear, a planetary gear, an outer ring gear, a planet carrier and a transmission shaft, and adopts a rigid gear; the planetary gear structure reducer is usually composed of a multi-stage planetary gear, and the transmission principle The gear with a small number of teeth meshes with the large gear on the output shaft to achieve the purpose of deceleration. The reducer is a transmission device with low torque and high torque and rigidity.

Harmonic geared motor: The transmission structure of the harmonic reducer consists of three basic components: a fixed internal toothed wheel, a flexible wheel, (ie, an elastic thin-walled cup whose base is connected to the driven shaft) is made on the busbar at the beginning of the flexible wheel. The ring gear") and the wave generator that causes the flex wheel to be radially deformed. The harmonic reducer is composed of a fixed internal gear rigid wheel, a flexible wheel, and a wave generator for radially deforming the flexible wheel. It has the characteristics of accuracy, bearing capacity and the like, compared with the ordinary reducer.

Through the above noun explanation, mainly in the structure is different, the planetary reducer has rigidity, the harmonic reducer structure adopts rigid and flexible gear meshing transmission; the harmonic reducer is the shock wave original reducer which relies on the eccentric flex gear The speed reducer, the relationship between it and the planetary reducer is that they belong to the reducer, and the other is basically no difference.

 Movement characteristics: According to the above combination, the motion characteristics of the simple planetary gear mechanism can be summarized into the following points:

(1) When the carrier is the active member, the follower is overspeeded.

(2) When the carrier is a follower, the carrier must be slower than the speed of the active member.

(3) When the carrier is fixed, the active member and the driven member rotate in opposite directions.

(4) When the sun gear is the active part, the speed of the follower must decrease.

(5) If the planet carrier acts as a passive member, its direction of rotation is in the same direction as the active member.

(6) If the planet carrier acts as the active member, the direction of rotation of the passive member is the same as it.

(7) In the simple planetary gear mechanism, the number of teeth of the sun gear is the least, and the number of equivalent gears of the planet carrier is the largest. The number of teeth of the ring gear is in the middle. (Note: The number of equivalent teeth of the planet carrier = the number of teeth of the sun gear teeth.)

(8) If any two components in the planetary gear mechanism rotate in the same direction at the same speed, the rotation speed and direction of the third component must be the same as the former two, that is, the mechanism is locked and becomes the direct gear. (This is a very important feature.)

(9) When there is only one active member and two other components are not fixed, it is in neutral at this time.

harmonic drive vs planetary gear

The harmonic actuator is mainly composed of four basic components: wave generator, flexible gear, flexible bearing and rigid gear. The harmonic drive reducer is a kind of flexible bearing assembled by the wave generator to make the flexible gear produce controllable elastic deformation. And meshes with the rigid gear to transmit motion and power. Applied disciplines: mechanical engineering (a subject); transmission (two subjects); gear transmission (three-level discipline) harmonic gear drive reducer is a new type of reducer developed using the principle of planetary gear transmission. Harmonic gear transmission (referred to as harmonic drive).

As a reducer, it is usually used in the form of a wave generator active, rigid wheel fixed, and flexible wheel output.

The wave generator H is a rod-shaped member which is provided with rolling bearings at both ends to constitute a roller, and is pressed against the inner wall of the flexible wheel 1. The flexible wheel is a thin-walled gear that can generate a large elastic deformation, and the inner diameter of the hole is slightly smaller than the total length of the wave generator. The wave generator is a member that causes the flexible wheel to produce a controlled elastic deformation. When the wave generator is inserted into the flexible wheel, the section of the flexible wheel is forced to change from the original circular shape to an elliptical shape, and the teeth near the two ends of the long axis are completely meshed with the teeth of the rigid wheel, and the teeth near the ends of the short axis are Completely disengaged from the wheel. The teeth of the other segments on the circumference are in a transitional state of engagement and disengagement. When the wave generator continuously rotates in the direction shown, the deformation of the flexible wheel is constantly changing, so that the meshing state of the flexible wheel and the rigid wheel is also constantly changed, by being engaged, engaged, engaged, disengaged, and then engaged. Repeatedly, the slow rotation of the flex wheel relative to the rigid wheel in the opposite direction of the wave generator H is achieved. When working, the fixed wheel is fixed, the motor generator drives the wave generator to rotate, and the flexible wheel acts as the driven wheel, and the output rotates to drive the load. During the transmission process, the wave generator turns one revolution, and the number of cycles of deformation at a certain point on the flex wheel is called the wave number, which is represented by n. Commonly used are two waves and three waves. The double-wave transmission has a small flex wheel stress and a relatively simple structure, making it easy to obtain a large transmission ratio. Therefore, it is the most widely used one.

 

harmonic drive vs planetary gear

Basic Features: 1. High load carrying capacity In harmonic drive, the tooth and tooth meshing is surface contact, and the number of meshing teeth (overlap coefficient) is relatively large, so the load per unit area is small, and the bearing capacity is higher than other transmission forms. 2. Transmission ratio The transmission ratio of single-stage harmonic gear transmission can reach i=70~500. 3. Small size and light weight. 4. High transmission efficiency and long life. 5. The transmission is smooth, no impact, no noise, and high motion accuracy. 6. Because the flexible wheel is subjected to a large alternating load, the requirements for fatigue strength, processing and heat treatment of the flexible wheel material are high and the process is complicated.

The harmonic reducer was only developed in China in the 1960s and 1970s. Many manufacturers have specialized production and serialization. Widely used in electronics, aerospace, robotics and other industries, due to its unique advantages, the application in the chemical industry is gradually increasing.

Harmonic gear reducers in aviation, aerospace, energy, marine, shipbuilding, bionic machinery, common ordnance, machine tools, instruments, electronic equipment, mining and metallurgy, transportation, lifting machinery, petrochemical machinery, textile machinery, agricultural machinery and medical Instruments and other aspects have been widely used, especially in high dynamic performance servo systems, the use of harmonic gear transmission shows its superiority. It transmits power from tens of watts to tens of kilowatts, but high-power harmonic gears are often used for short-term work.

Gear reducer hydrostatic transmission system can convert mechanical energy into liquid pressure energy, which increases the convenience of wind steering. The speed reducer and the piping system of the reducer and the kiln transmission thin oil humidification system, the pressure maintaining wheel, the vertical grinding machine, the ball mill and the supporting hard tooth surface reducer cannot be separat
When inspecting, according to the shaft temperature and resonance diagram of the gear reducer, combined with the parameters of the components and instruments of the thin oil lubrication system, analyze whether the osmotic pressure transmission system is normal.

The reducer lubrication body system includes a lubrication body system and a side pressure, temperature control system. The lubrication main system consists of a fuel tank and a fuel tank, which in turn are the main pump, the coupling and the variable frequency motor. The main pump has passed the pipeline pressure reducer for several consecutive years, and the pressure gauge is successively arranged on the continuous pipeline of the main pump and the pressure reducer. Side pressure sensors, duct heaters, tube coolers, temperature sensors and filters, cooling water operating water valves in the cooler cooling water outlet piping, and bypass valves that are connected to the tank in one hand are retained between the filters. Connecting pipe and reducer

The gear reducer has a complete nodulation system that meets zero environmental requirements. It should be strictly enforced.

 

 
 

harmonic drive vs planetary gear

 

Planetary gears refer to gear systems that, in addition to being able to rotate around their own axis of rotation like fixed-axis gears, their axes of rotation also rotate with the planet carrier about the axis of the other gears. The rotation around its own axis is called "rotation", and the rotation around the other gear axes is called "revolution", just like the planets in the solar system, hence the name.

Planetary gear means that the axis of rotation is not fixed, and the planetary gears are mounted on a rotatable bracket. In addition to rotating around their own axis of rotation (BB) like a fixed-axis gear, their axes of rotation also follow the blue The bracket (called the planet carrier) rotates about the axis (AA) of the other gears. The rotation around its own axis is called "rotation", and the rotation around the other gear axes is called "revolution", just like the planets in the solar system, hence the name.

The planetary gear mechanism is divided into a single planetary row and a double planetary row according to the number of planetary gears installed on the planet carrier. Planetary gearing has many unique advantages over conventional gearing. The most notable feature is that power splitting can be performed while power is being transmitted, and the input and output shafts are on the same horizontal line. Therefore, planetary gear transmissions have been widely used in various mechanical transmission systems, such as reducers, speed increasers and shifting devices. Especially because of its "high load, large transmission ratio" characteristics, it is widely used in aircraft and vehicles (especially heavy vehicles). Planetary gears also play a large role in the torque transmission of the engine. Since the characteristics such as the engine's rotational torque and the road running demand are quite different, the power of the engine is appropriately distributed to the drive wheels, and the above characteristics of the planetary gears can be used for the conversion. The automatic transmission in the automobile also utilizes these characteristics of the planetary gears to obtain different gear ratios by changing the relative motion relationship of the respective members by the clutch and the brake.

The planetary gear mechanism is divided into a single planetary row and a double planetary row according to the number of planetary gears installed on the planet carrier. Planetary gearing has many unique advantages over conventional gearing. The most notable feature is that power splitting can be performed while power is being transmitted, and the input and output shafts are on the same horizontal line. Therefore, planetary gear transmissions have been widely used in various mechanical transmission systems, such as reducers, speed increasers and shifting devices. Especially because of its "high load, large transmission ratio" characteristics, it is widely used in aircraft and vehicles (especially heavy vehicles). Planetary gears also play a large role in the torque transmission of the engine. Since the characteristics such as the engine's rotational torque and the road running demand are quite different, the power of the engine is appropriately distributed to the drive wheels, and the above characteristics of the planetary gears can be used for the conversion. The automatic transmission in the automobile also utilizes these characteristics of the planetary gears to obtain different gear ratios by changing the relative motion relationship of the respective members by the clutch and the brake.

However, due to the complex structure and working state of the planetary gears, the vibration and noise problems are also prominent. It is prone to failure phenomena such as gear tooth fatigue pitting, root cracks and even gear teeth or shaft breakage, which affects the running accuracy of the equipment. Transfer efficiency and service life.

 

 
 

harmonic drive vs planetary gear

Structure and composition: A simple (single row) planetary gear mechanism is the basis of the shifting mechanism. Usually, the shifting mechanism of the automatic transmission is composed of two or more rows of planetary gear mechanisms. The simple planetary gear mechanism includes a sun gear, a plurality of planet gears, and a gear ring, wherein the planet gears are supported by a fixed shaft of the planet carrier, allowing the planet wheels to rotate on the support shaft. Planetary gears and adjacent sun gears and ring gears are always in a meshing state, and helical gears are usually used to improve the smoothness of the work.

In the simple planetary gear mechanism, at the center of the planetary gear mechanism is a sun gear, the sun gear and the planet gear are often meshed, and the two outer gears mesh in opposite directions of rotation. Just as the sun is at the center of the solar system, the sun wheel is named for its location. In addition to being able to rotate around the planet carrier support axis, in some cases, it will rotate around the central axis of the sun gear under the driving of the planet carrier. This is like the rotation of the earth and the revolution around the sun. When this happens, it is called the transmission mode of the planetary gear mechanism. In the entire planetary gear mechanism, such as the existence of the planetary gear rotation, and the planet carrier is fixed, this type of transmission is similar to the parallel shaft type transmission. The ring gear is an internal gear that is constantly meshed with the planet gears, and the internal teeth and the external gears mesh with each other in the same direction of rotation. The number of planetary gears depends on the design load of the transmission, usually three or four, and the more the number, the greater the load.

A simple planetary gear mechanism is often referred to as a three-component mechanism, and the three components are referred to as a sun gear, a planet carrier, and a ring gear, respectively. If these three components are to determine the mutual motion relationship, in general, firstly, one of the components needs to be fixed, then determine who is the active component, and determine the rotational speed and rotation direction of the active component, and the rotational speed and rotational direction of the passive component are determined. It is.

Principle and characteristics: Transmission combination In a gear system that includes planetary gears, the transmission principle is different from that of a fixed shaft gear. Due to the existence of the planet carrier, there are three rotating shafts that allow power input/output, and a clutch or brake or the like can be used to limit the rotation of one of the shafts when needed, leaving only two shafts for transmission. Therefore, the relationship between the intermeshing gears can be combined in many ways:
(1) The power is input from the sun gear, output from the outer ring gear, and the planet carrier is locked by the mechanism;
(2) The power is input from the sun gear, output from the planet carrier, and the outer ring gear is locked;
(3) The power is input from the planet carrier, output from the sun gear, and the outer ring gear is locked;
(4) The power is input from the carrier, output from the outer ring gear, and the sun gear is locked;
(5) The power is input from the outer ring gear, output from the planet carrier, and the sun gear is locked;
(6) Power is input from the outer ring gear, output from the sun gear, and the planet carrier is locked;
(7) The two powers are input from the sun gear and the outer ring gear respectively, and are synthesized and output from the planet carrier;
(8) The two powers are input from the planet carrier and the sun gear respectively, and are output from the outer ring gear after synthesis;
(9) The two powers are input from the planet carrier and the outer ring gear respectively, and are output from the sun gear after synthesis;
(10) The power is input from the sun gear and is output from the outer ring gear and the planet carrier in two ways;
(11) Power is input from the carrier, and is output from the sun gear and the outer ring gear in two ways;
(12) Power outer ring gear input, divided into two channels from the sun gear and the planet carrier.

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