synonymStepless transmission(equipment used in humid, dusty and slightly corrosive working environment) generally refers to the continuously variable transmission
Nonsegmentvariable-speed motorIt can also be calledStepless transmission、Stepless transmissionAnd stepless transmission.The most common CVT are hydro mechanical CVT and metal belt CVT, which are used to change or adjust equipment and energy changes.The continuously variable transmission is mainly composed of the pressing driving wheel device, friction transmission mechanism and speed control mechanism, which belongs to the gear transmission device that can fix or shift the transmission ratio of output shaft and input shaft.The CVT can select a variety of complex operation procedures such as speed change, braking, forward and reverse conversion, slow start, slow deceleration, etc.
Continuously variable transmission is usually connected withGear reducer, double flange electromagnetic clutch brake setRV worm gear reducerEtc.It has been widely used in production lines, textile machinery, printing and dyeing machinery, wires and cablesMechanics, food machinery, leather machinery, woodworking machinery, packaging machinery, electronic equipment, manufacturers and other fields.[1]
characteristic
1. High strength, reliable performance and accurate rotation in case of impact loading or machine reversal;
2. Large speed range, high speed regulation accuracy, stable performance, small size and light weight;
3. Transmission parts have undergone special heat treatment, precision processing friction parts;
4、lubricationGood, stable operation, low noise and long service life;
5. Good interface characteristics, easy speed change.During operation, whether under load or not, it can change speed quickly and reliably;
6. With strong combination ability, it can be combined with various types of reducers to achieve the speed change effect of low speed and large torque gauge;
7. The set speed can be constant under the condition of allowable load;
8. Fully enclosed mechanical speed change, suitable for humid, dusty, slightly corrosive working environment.
Usage
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1. When installing horizontal and vertical continuously variable transmission machines, the center line elevation of the machine should be calibrated, and the coaxiality of the transmission shaft should not exceed the allowable range of the coupling.
2. The output shaft is equipped with a couplingpulleyAnd can not be knocked.The coupling should be pressed in with the screw hole at the outer end of the output shaft.
3. In useStepless transmissionAdd the specified lubricating oil before, and the oil level must exceed the center of the oil mirror.
4. Generally, the adjustment limit screw of the newly delivered continuously variable transmission has been adjusted to the limit position, so it is not allowed to adjust it at will to avoid damage to the parts.
5. It can operate in both positive and negative directions, but shall not exceed the rated valuetorqueuse.It is recommended that the maximum number of starts per minute of the prime mover input at the same time be less than 6.
Note that too high starting frequency will affect the service life of CVT.For the simultaneous replacement of lubricating oil and maintenance, please refer to the Operating Manual of the Continuously Variable Transmission for details.[1]
working principle
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The system mainly includes driving wheel set, driven wheel set, metal belt, hydraulic pump and other basic components.The metal belt consists of two bundles of metal rings and hundreds of metal sheets.The driving wheel set and driven wheel set are composed of movable disc and fixed disc, andCylinderThe pulley on the adjacent side can slide on the shaft, and the other side is fixed.Both movable disc and fixed disc are conical structures, and their conical surfaces form V-shaped grooves to mesh with V-shaped metal transmission belts.The power output from the engine output shaft is first transmitted to the driving wheel, then to the driven wheel through the V-belt, and finally to the wheel through the reducer and differential to drive the car.During operation, the movable disc of the driving wheel and the driven wheel moves axially to change the driving wheelDriven wheelThe working radius at which the cone engages with the V-belt, thereby changing the transmission ratio.The axial movement of the movable disc is realized by the driver by adjusting the pressure of the hydraulic pump cylinder of the driving wheel and the driven wheel through the control system as required.Since the working radius of the driving wheel and the driven wheel can be continuously adjustedStepless speed change。
stayMetal belt continuously variable transmissionOfhydraulic pressureIn the system, the role of the slave cylinder is to control the tension of the metal belt to ensure the efficient and reliable transmission of power from the engine.The driving cylinder controls the position of the driving cone wheel to move along the axial direction. The metal belt of the driving wheel group moves along the V-shaped groove. Since the length of the metal belt is unchanged, the metal belt of the driven wheel group changes in the opposite direction along the V-shaped groove.The turning radius of the metal belt on the driving wheel set and the driven wheel set changes, realizing continuous change of the speed ratio.
When the car starts to start, the working radius of the driving wheel is small, and the transmission can obtain a larger transmission ratio, thus ensuring that the drive axle can have enough torque to ensure that the car has a higher acceleration.With the increase of vehicle speed, the operation of driving wheelradiusGradually decrease, the working radius of the driven wheel increases correspondingly, and the transmission ratio decreases, so that the car can run at a higher speed.[2]
classification
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Friction type stepless transmission
The existing friction variable speed transmission mechanisms have various structural types.Generally, it can be divided into:
(1) Direct drive type, namely, the main and driven friction elements are in direct contact with the drive;
(2) Intermediate element type, that is, the driving and driven elements are carried out through the intermediate elementtransmission；
(3) Planetary transmission type, that is, the transmission mechanism in which the middle element performs planetary motion.The pressurizing device is used to generatefrictionThe pressing force between the driving working surfaces. The size and change of this force is directly related to the carrying capacity and performance of the drive. Therefore, the pressure device is alsoStepless transmissionThe basic components of.Generally, there are pressure springs and end facesCamPressurization, steel column V-groove pressurization.The speed regulating mechanism is mainly used to make the friction elements move or rotate relatively to achieve speed regulation. The main requirements for the transmission are simple structure, reliable operation, portability, flexibility and accurate positioning.The most widely used speed regulating mechanism is screw mechanism and worm gear mechanism.
Chain stepless transmission
Continuous stepless transmission is a kind ofSprocketAnd a steel flexible chain as a transmission element to transmit movement and power.Its basic components include transmission mechanism, speed regulating mechanism and chain tensioning mechanism.
Transmission mechanism: the transmission mechanism composed of sprocket and chain is chain typeStepless transmissionMain body mechanism of, input and output of transmissionspeedThe transformation of is mainly realized through him.
Speed governing mechanism: the function of the speed governing mechanism is to make the two pairs of cone discs of the driving and driven sprockets move axially opposite or opposite each other, that is, one pair of cone discs open and the other pair of cone discs close, so that the contact radius (namely, the working radius) of the chain that keeps tension with the two sprockets increases or decreases respectively.Since the linear speed of two chains and sprockets in contact with the working circle is equal (equal tochainSpeed), so different ratios of working radii of driving and driven sprockets form different transmission ratios, thus realizing speed change.Chain tension and compression mechanism: like other friction drivesTransmissionThere must be a chain tensioning and pressurizing mechanism in the.At present, the commonly used tensioning and pressurizing devices can be basically divided into two types, one is by means of shoe pressing, the other is by means ofCamAutomatic pressurization mode.[2]
Belt continuously variable transmission
And chainTransmissionSimilarly, its variable speed transmission mechanism is composed of two pairs of chasing discs as driving and driven pulleys and the transmission on which the tension is applied.Its working principle is also produced by using the left and right sides of the drive belt and the cone platefrictionDrive, and adjust the contact position and working radius between the two cone discs and the drive belt by changing the axial distanceStepless speed change。Band steplessTransmissionAccording to the shape of the drive belt, it can be divided into flat belt CVT and V-belt CVT.
Pulse type continuously variable transmission
The main mechanism of the transmission is mainly composed of connecting rodmechanismComposition, or combination of connecting rod, cam, gear and other mechanisms, its working principle isLinkageThe same, but in order to enable the output shaft to obtain continuous rotating movement, an output mechanism (such as an overrunning clutch) needs to be configured here.The pulse type stepless transmission is composed of transmission mechanism, output mechanism and speed regulating mechanism. The transmission mechanism is its theme mechanism, and the input and output of the transmissionspeedThe transformation of is mainly realized through it.However, in order to convert the reciprocating swing of the remote rod into one-way rotary motion output, the transmission must be equipped with an output device.In order to realize stepless speed change, a speed regulating mechanism is also required in the transmission, which is used to changecrankLength, to form a variety of different size proportional relations, so that the swing angle and average swing speed change, to achieve speed change.[1]
