Main clutch, the driven part transmits power or motion coaxially, having means engaging or separating function. Flywheel shell clutch located between the engine and gearbox, clutch assembly is fixed with screws on the back plane of the flywheel, clutch gearbox output shaft is the input shaft. In the process of moving the car, the driver may need to depress or release the clutch pedal, the engine and gearbox temporary separation and gradually engaged to cut or transfer of power from the engine to the transmission input.
Including active part, driven part, the press mechanism and control mechanism. The active part are: flywheel, clutch cover and pressure plate; driven partly driven plate; pressing means is a compression spring; the control mechanism have separate fork, release bearing, clutch pedal and transmission parts.
1、to ensure a smooth start car
This is the primary function of the clutch. In the car started before, the natural first start the engine. The car started, the car is completely stationary state from the gradual acceleration. If the drive train (which links the whole car) rigidly contact with the engine, the transmission of a hanging file, the car will suddenly look forward, but it does not start. This is because when the car from standstill to pediment, has great inertia, causing the engine drag torque greatly. In this moment of inertial resistance effect, a sharp decline in the blink of time the engine speed to a minimum steady speed (typically 300-500RPM) below, the engine stalled and that does not work, of course, the car can not be started.
Therefore, we need the help of the clutch. After starting the engine, before the car started, the driver depresses the clutch pedal to the clutch, the engine and drivetrain disengaged, then the transmission in gear, and then gradually release the clutch pedal, the clutch engages gradually. During engagement, the engine torque is gradually increased hindered, it should be while gradually depressing the accelerator pedal, i.e., gradually increasing the amount of fuel supplied to the engine, the engine's speed is always maintained at a minimum steady speed, without flameout. Meanwhile, due to the tightness of clutch engagement increases, the engine torque transmitted to the drive wheels via the drivetrain will gradually increase, when the traction is sufficient to overcome the initial resistance, the car starts moving from standstill and gradually accelerate
2、to achieve smooth shifting
In cars with the process, to adapt to changing driving conditions, the drive train to be replaced often work different stalls. Gear shift gearbox, usually hanging files toggle gear or other agencies, to allow use of a gear transmission gear pair to launch, and then make another gear gear pair into the work. Before shifting the clutch pedal must interrupt power transmission, facilitates gear meshing pair disengaged original, while the speed of the new parts of the meshing gear pair gradually tend to synchronize the time of impact can be brought into engagement so greatly reduced, to achieve smooth shift.
3、to prevent transmission system overload
Issued when an emergency brake when the car, if there is no clutch, the engine and drivetrain rigidity will vary drastically reduced connection speed, and thus all the moving parts of which will have a great moment of inertia (its value may be much higher than normal engine work the maximum torque) of the drive train caused more than its load carrying capacity, leaving the mechanical damage. With the clutch, the clutch can rely on the active part and the relative motion between the driven part may have to eliminate this risk. Therefore, we need to limit the maximum torque clutch driveline to bear to ensure safety.
Electromagnetic clutches and clutch points magnetic clutch, friction clutch, fluid couplings
Need to be able to work at any time according to the drive shaft and the driven shaft to engage or disengage the mechanical parts. Transmission system can be used to operate the machine start, stop, speed and commutation and so on. Clutch variety, according to the nature of the work can be divided into: ① actuated clutch. Its manipulation methods include mechanical, electromagnetic, pneumatic and hydraulic, etc., such as embedded clutch (tooth by tooth or key chimeric transmission torque), the friction clutch (torque transmitted by a frictional force), the flexible air clutch (with compressed air tire expansion and contraction to manipulate friction clutch engagement or separation), electromagnetic slip clutch (with excitation current to generate a magnetic torque transmission), magnetic clutch (magnetic powder magnetized by the excitation coil, magnetic particle chain formation to transmit torque). ② automatic clutch. By simple mechanical means to automatically complete the bonding operation or separate, is divided into safety clutch (transmitted torque when the drive shaft reaches a certain value can be automatically separated, so as to prevent overload, the important parts of the machine to avoid damage),Centrifugal clutch (if the speed of the drive shaft reaches a certain value, after centrifugal force enables coupling between the shaft or exceeds a self-rotational speed can be separated on their own), directional clutch (also known as overrunning clutch, the use of ratchet - engagement pawls or roller, wedging effect of the one-way wedge transmit motion or torque, or reverse when the driving shaft speed is less than the driven shaft, the clutch is automatically separated).
1. electromagnetic clutch
By coils through power to control the clutch engaged and disengaged.
Electromagnetic clutch can be divided into: dry electromagnetic clutches, electromagnetic multi-plate dry clutch, wet multi-plate electromagnetic clutch, magnetic clutch, electromagnetic clutch slip.
Electromagnetic clutch work can be divided into: power combining and power combined.
Dry electromagnetic clutches: generating a magnetic pull "keeper", clutch engaged state when the coil is energized; coil power "armature" bounce, the clutch is disengaged state.
Dry multi-plate wet multi-plate electromagnetic clutch: principle above, an additional pay several friction, torque equal volume dry-large monolithic electromagnetic clutch, must have oil or other cooling liquid cooled wet multi-plate electromagnetic clutch work.
2. magnetic clutch
Between active and follower placement magnetic powder, magnetic powder in a loose when not energized state, when power is combined with magnetic powder, active member and the driven member is rotated at the same time. Advantages: can be adjusted by adjusting the torque current, allowing a larger slip. Disadvantages: large slip when the temperature rise is large, relatively high price
Slip electromagnetic clutch: clutch work, Lord, from part of a speed difference there must have torque transmission. Torque depends on the magnetic field strength and the speed difference. Excitation current remains unchanged, the increase of speed versus torque dropped dramatically; torque remains unchanged, the excitation current is reduced, reducing the speed even more serious.
Electromagnetic clutch slip due to the Lord, between the driven member without any mechanical connection, no wear and tear, no magnetic powder leakage, no shock, adjust the excitation current can change the speed, continuously variable transmission for use, which is its advantage. The main disadvantage of the clutch rotor eddy current generates heat, and this heat is proportional to the speed difference. Low speed operation is inefficient, efficiency value based, the rotational speed ratio of the driven shaft, i.e. η = n2 / n1
Mechanical transmission system suitable for high frequency operation, in the case of the active part can be operated, in conjunction with the driven portion of the active part or separated.
When the state of separation between active member and follower, active member is rotated, the follower stationary; engaged state between active member and follower, the initiative to bring the rotation between the follower.
Widely used in machine tools, packaging, printing, textile, light industry, and office equipment.
Electromagnetic clutch is generally used for ambient temperature -20-50% humidity is less than 85%, non-explosive medium, the coil voltage fluctuations do not exceed the rated voltage of ± 5%
3. friction clutch
At present, widely used in the car with a spring-loaded friction clutch (referred to as a friction clutch). Compatible with the majority of the manual transmission clutch dry friction clutch, driven by its number plate, divided into single disc, double disc and multi disc several. According to other criteria, the friction clutch is divided into two kinds of dry and wet. Wet friction clutch disc is generally more, and immersed in oil for heat dissipation. Using a number of coil springs as a compression spring, and the spring along the circumference of the distribution of the pressure plate clutch spring clutch These are called peripheral cloth. As the use of the diaphragm spring clutch compression spring called diaphragm spring clutch.
Torque of the engine emitted by friction flywheel and pressure plate and driven plate contact surface, passed driven disc. When the driver depresses the clutch pedal, by passing the parts, so that the large end of the diaphragm spring pressure to drive late shift, this time driven part and active part of the separation.
Friction clutch should be able to meet the following basic requirements:
(1) guaranteed to deliver maximum torque of the engine issue, and there is some spare capacity to transmit torque.
(2) separation can be done, completely separated, the bonding soft, and has good heat dissipation ability.
Moment of inertia (3) driven portion as small as possible. Thus, in the separation of the clutch gear, and the transmission input shaft rotational speed portion connected relatively easily changed, so as to reduce the impact between the gears.
(4) having a rotational direction to ease the impact, the direction of the vibration damping ability, and low noise.
(5) the coefficient of friction and the friction plate pressure plate pressure variation is small, stable.
(6) steering effort, easy maintenance.
4. The fluid coupling
By hydraulic coupling fluid (oil) to transmit torque, housing and the impeller as a single entity, is an active member; turbine wheel relative to the pump is driven member. When the pump rotor speed is low, the turbine can not be driven between the follower and active member state of separation; with increasing impeller speed, the turbine is driven between the follower and active member in the engaged state.