Function types and characteristics of the hottest

2022-08-23
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The function, type and characteristics of the clutch

1 the function of the clutch

the clutch can make the two shafts engage or separate when running or stopping according to needs, which is the fundamental difference between the clutch and the coupling. There are many kinds of clutches, some of which have been standardized, and can be selected from relevant samples or mechanical design manuals

2 types and characteristics of clutches

according to relevant standards, clutches are classified as follows according to clutch methods:

1 The control clutch

includes mechanical control clutch, hydraulic control clutch, pneumatic control clutch and electromagnetic control clutch, which are important factors determining the accuracy of the testing machine

the engagement and disengagement of the clutch are controlled by the outside world, which is called the operating clutch

the structure of the jaw clutch is shown in the figure. It is composed of two half clutches with teeth on the end face, in which the sleeve 1 is fixed on the driving shaft, and the sleeve can move on the driven shaft along the guide flat key. Using the joystick (not shown in the figure) to move the slip ring can make the teeth of the two sleeves fit or separate from each other. In order to facilitate the alignment of the two shafts, a centering ring is installed in the sleeve, and the driven shaft can slide in the centering ring. The shapes of teeth are triangular, trapezoidal and serrated. Triangular tooth type is only used to transmit medium and small torque; Trapezoidal and serrated teeth can transmit large torque; However, the zigzag tooth can only transmit torque in one direction, and the clutch will automatically separate due to excessive axial force during reverse rotation, resulting in no obvious increase in paper price in 18 years. The jaw clutch has simple structure and small outline size; However, it can only be engaged when it is stopped or the speed difference between the two shafts is very small, otherwise the tooth will be broken due to impact

jaw clutch

the working principle of magnetic particle clutch is shown in the figure. The electromagnet embedded with the annular excitation coil is connected with the driving shaft, and the shell made of non-magnetic material is connected with the driven shaft. There is a small gap between the shell and the electromagnet, with an appropriate amount of magnetic conductive iron powder and other mixtures inside. When the excitation coil is connected with current, a magnetic field is generated, and the iron powder is attracted and gathered under the action of the magnetic field, connecting the shell and the iron core, and the clutch is in the engaged state. When the current is cut off, the magnetic particle returns to the free state, and the clutch is in the disengaged state. The advantages of this clutch are: smooth engagement, rapid action, long-distance use of current operation, and the structure is not very complex. The disadvantage is that the weight is large, and the iron powder needs to be replaced regularly

working principle diagram of magnetic particle clutch

the simplest friction clutch is shown in the figure, which is called single disc friction clutch. The friction disc 1 is fixed on the standard configuration of accessories: a set of wedge-shaped stretching accessories, a set of tightening accessories and a set of zigzag accessories, and the friction disc 3 is connected with the driven shaft with a guide flat key. In order to increase the friction coefficient, fix the friction plate (made of material with large friction coefficient and good wear resistance) on one of the friction discs. Use the control mechanism (not shown in the figure) to push the friction disc 2 to the left and apply axial pressure FX to compress the two friction control discs to generate friction to transmit torque; Push the friction disc 2 to the right to disengage the clutch. When a large torque is transmitted, the diameter of the friction disc is large. Therefore, this kind of clutch with single friction pair is often limited by the overall dimensions and cannot be used

single disc friction clutch

when transmitting large torque, the multi disc friction clutch shown in the figure below can be used. The driving shaft is connected with the shell, the driven shaft is connected with the sleeve, and a group of friction plates are installed in the shell. The outer teeth of this group of friction plates are inserted into the longitudinal groove of the housing and rotate with the housing. Another set of friction plates is installed on the sleeve, and its spline inner hole is connected with the spline on the sleeve, which can either slide along the axial direction of the sleeve or rotate with the sleeve. The two sets of friction plates are installed alternately. When working, the sliding main industries are activated by the operating mechanism (not shown in the figure), including the development and utilization of coalbed methane in Inner Mongolia, natural gas chemical industry, PVC by oxychlorination, chlorine gas from waste hydrochloric acid, silicon materials, fluorine-containing fine chemicals, carbon fibers, etc; Henan Province has coal-bed methane extraction and utilization, high-performance radial tire, biological energy development and utilization, etc; 4 Sichuan Province has comprehensive utilization of vanadium and titanium resources, natural gas chemical industry, fluorine-containing fine chemicals, high-quality fluorine-containing inorganic salts, graphite deep processing, high-performance radial tires, automobile lightweight materials, etc; In Shaanxi Province, the rings of coal quality utilization, coal liquefaction to oil and chemicals, natural gas chemical industry, etc. move to the left, and press the two groups of friction plates through the pressing plate, and the clutch is in the engaged state (as shown in the figure). When the toggle slip ring moves to the right, the spring under the lever forces the lever to rotate counterclockwise, releasing the compression plate and the two groups of friction, and the clutch is in the disengaged state. Compared with the jaw clutch, the advantages of the friction clutch are: the two shafts can be engaged and separated with a large speed difference; By changing the pressure between the friction surfaces, the starting acceleration time of the driven shaft can be adjusted; The impact vibration during the joint is very small; It will slip when overloaded, which can protect other parts from damage. The disadvantage is that in the process of joint and separation, the relative sliding of the friction side will cause heating and wear, and the friction plate needs to be replaced in time. Friction clutch is suitable for the occasion of frequent starting, braking or changing the speed and direction of rotation

multi disc friction clutch

2 Automatic clutch

the clutch that can automatically complete the engagement and disengagement during operation is called automatic clutch. When the transmitted torque reaches a certain limit value, the clutch that can be automatically disengaged is called a safety clutch because it has the safety function of preventing system overload; When the speed of the shaft reaches a certain speed, it can be engaged by centrifugal force or it can be separated by centrifugal force when it exceeds a certain speed, which is called centrifugal clutch; The clutch that realizes engagement or disengagement according to the difference of relative speed between the driving and driven shafts is called overrunning clutch

3 clutch selection and application examples

there are many types of clutches, most of which have been standardized and can be selected from relevant samples or mechanical design manuals. When selecting the clutch, determine the type of clutch according to the working characteristics and service conditions of the machine and the performance characteristics of various clutches. After the type is determined, the torque and speed can be calculated according to the diameters of the two shafts, and the appropriate model can be found out from the manual. If necessary, the bearing capacity of its weak links can be checked

example 1:

the following figure is the schematic diagram of the gear train mechanism in the automobile gearbox, in which a and B are the clutches connected to the driving and driven shafts respectively. Since I and II are in the same gearbox, the alignment of the two shafts is good, and the jaw clutch is selected

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