The beginning of the creation of variable gears was laid in the last century. Even then, a Dutch engineer mounted it on a vehicle. After such mechanisms were used on industrial machines.
A variator is called a mechanism that provides smooth transmission of torque from the power plant to the elements that drive the vehicle in motion. Often such a device is called the most compact stepless box. It is difficult for the average car owner to distinguish between variable and automatic transmissions.
The principle of operation of the variator provides for effective synchronization with the crankshaft, and torque transmission is continuous, which makes it possible to significantly save fuel consumption. Transmissions of this type can be used on cars, motorcycles, scooters, but the gearbox experiences such a load that does not allow its installation on trucks. This article will consider: CVT, CVT gearbox, device, principle of operation.
Design
So, we will analyze the component parts. The device and principle of operation of the variator - has a large number of parts. The main units are:
- device for disconnecting the crankshaft and transmission;
- variable speed;
- additional reverse gear (gears of this type do not include a backward movement design; for this, a conventional planetary gearbox is mounted);
- a control unit that controls torque transmission and acceleration;
- a centrifugal automatic clutch mechanism and an additional unit consisting of an electromagnet, and is controlled by an electronics system;
- hydraulic type transformer.
This is the general structure of the variable box. There are also various assemblies of such transmissions that differ in the type of torque transmission.
CVT - principle of operation, variator types
design improvements became the reason that several principles of operation of this device appeared:
V-belt design . The rotation of the crankshaft is transmitted to the propulsors using one or two strong belts. They are manufactured using special technology to ensure a high working resource. Such a belt drive is mounted on two pulleys consisting of pairs of conical disks.
The trick of such a design solution is the variable diameter of the pulleys. Reducing and increasing the size of the cones occurs with the participation of the hydraulic system,
centrifugal force and spring supports. The cones are placed on a slope that minimizes friction.
One of the first such transmissions often failed due to the fault of the belt. Modern automotive industry produces belt drives using innovative technologies that provide a working life of up to 2,000,000 kilometers traveled. Belts are made by weaving a special wire, set and fastening steel plates between each other. Moreover, such a transmission has good flexibility. It is these technical solutions that made it possible to attribute such a gearbox to the category of certain types of transmissions.
Variators with wedge chain drive . As a belt, a chain link is used that has good flexibility. With this system, conical pulleys are made of special types of steel due to high loads. Such a scheme and the principle of operation of the variator have a high efficiency. And all because energy losses are significantly reduced.
How it works?
What is a variator, the principle of operation of a variator? The variable gearbox can only be controlled electronically. It requires a quick response to an increase in the crankshaft speed and calculation of the movement of the cones to change the pulley diameters. Moreover, electronics takes into account the specific mode of the power plant, clutch and other components in real time.
The driver controls the transmission with a lever having a set of functions similar to an automatic transmission. Electronics with the help of calculations makes the diameter of the pulleys corresponding to the highest efficiency. When the revolutions at the exit from the motor increase, the conical disks approach each other and the pulley’s bore diameter increases. In parallel, the gear ratio is reduced. Moreover, there is a system responsible for the synchronism of movement of the conical parts. Their position and gaps are controlled by a sensor-regulator.
In the case of conical parts moving apart, the belt belt bends around the pulley in a small circle and, when narrowing, along a large diameter. Many motorists do not even wonder: what is a variator, device and principle of operation? This device is simply called a automatic gearbox, but in design they differ significantly.
Transmission Behavior during Acceleration and Rise
When the car accelerates, this does not indicate a parallel increase in engine speed.
They remain unchanged during the increase in speed. The variable box independently and smoothly changes the gear ratio. In the case of a rise, when the car starts to slow down somewhat, the variator will reduce the
gear ratio and do the opposite procedure. The engine operating modes with such a transmission are advantageous.
Maintenance
The device and the principle of operation of the variator makes its service inspection and troubleshooting an expensive and time-consuming operation. Eliminating serious damage to the belt or other parts is a costly affair. A special gear oil is used for the lubrication system and has a high cost in the absence of warranty service.
On-board problems can be warned by the on-board computer, which has a self-diagnosis function and a diagnostic connector. With the help of the latter, service workers are connected to the electronics system for reading fault codes and their subsequent cleaning. CVTs can be used on vehicles of small traction class.
Do I need to warm up the engine when starting the movement?
For departure on the road the cars equipped with variable gearboxes, the engine has to be warmed up.
This is explained by the need to heat the lubricating fluid and deliver it to all nodes and assemblies. If grease is not supplied to some parts, this will increase wear and speed up the need for repairs. You also need to periodically look at the level of gear oil. Only after the warm-up procedure is it possible to start moving. For the absence of overloads and malfunctions, it is worth abandoning the towing of cars and driving on unsatisfactory roads.
CVT (clutch) - principle of operation, device
A clutch mechanism is used to transmit revolutions of the shaft elbows to the variable gearbox . It consists of a housing, a driven and a leading disk with damper springs and friction pads, a release mechanism. One disk is mounted on the motor shaft and rotates with the shaft. The second element is installed at the inlet of the box and, under the action of the clamping force, connect, transmitting torque to the gearbox.
After that, the rotation will be transmitted to the wheels.
Positive aspects
The principle of operation of the variator allows you to make the car work dynamically. Efficient engine operation shows good fuel economy. When driving in slippery conditions, slippage will be eliminated. In the movement there will be no jerks and jerks, unlike a mechanical box. Emission factors will be lower than ordinary cars, and acceleration faster.