The device of a robotic box with two clutches:
The device of a robotic box with two clutches
1 - the primary shaft of even gears
2 - a primary shaft of odd gears and reverse
3 - oil pump
4 - double clutch
5 - hydraulic switching mechanism
6 - the sensor of the included gear
7 - an oil filter
8 - electro-hydraulic unit
The main advantages and disadvantages of automatic machines are known: convenient in everyday use, gears are switched without interrupting the flow of power. But you have to pay for it with higher fuel consumption and worse dynamics. With mechanics, the opposite is true: it is cheaper, more economical, but not everyone likes to make countless movements with arms and legs. The solution was found in a two-clutch robotic transmission. Such a unit itself shifts gears and at the same time is not inferior to manual gearboxes in economy.
This unit has two rows of gears, each connected to the engine flywheel through its own clutch. One row is odd gears and reverse, the second is even. During acceleration, they switch sequentially. The car starts off in first gear, and the gearbox already holds the second gear ready, only the moment is not transmitted through it - the clutch is off. As soon as you need to switch to an overdrive, the discs of the first clutch will open, and the other - on the contrary, will converge. With the second gear in the other row, the third is ready. The process is fast, without jerking and breaking the power flow. Yes, and the efficiency of the transmission is the same as that of a conventional manual gearbox - hence the high efficiency.
The algorithm for switching to lower gears depends on the degree of pressing the accelerator, the intensity of deceleration, the speed of the car. For example, from the sixth box can jump directly to the second, only for a split second lingering at the fifth speed of a parallel row.
Scheme of distribution of torque in a box with a double clutch
The first (solid line) and second (intermittent) gears are engaged, but only one clutch is closed and only the gears of the first stage transmit the moment. The second is waiting for the electronics to switch the clutch:
Scheme of distribution of torque in a box with a double clutch
1 - clutch number 1
2 - clutch number 2
3 - a primary shaft of even gears
4 - a primary shaft of odd gears
5 - wheel drive
6 - differential
There are two types of clutch in these transmissions: “wet” and “dry”. The first is a clutch with a pack of discs in oil. Electronics gives the command to the actuators, the hydraulic cylinder compresses the discs, the clutch closes. To open, the pressure in the actuator decreases - and the diaphragm spring returns the piston of the hydraulic cylinder to its original position.
The “dry” clutch resembles that on cars with a conventional manual gearbox, but instead of one unit there are two. They are installed sequentially, each with its own drive, basket, driven disk. Between the clutches is the drive disc associated with the engine flywheel. Automation in turn pulls one lever or another, including the clutch of the first or second shafts - the basket presses the driven disk to the drive and the torque from the engine flows into the box.
The principle of operation of the "dry" clutch:
The principle of the "dry" clutch
a - the first clutch is engaged, the torque is transmitted to the odd gear shaft
(captions in the figure: 1 - the input shaft of the odd gears; 2 - the pressure plate; 3 - the driven disk; 4 - the drive disk; 5 - the release bearing; 6 - the flywheel);
b - the second clutch is engaged, the torque is transmitted to the even gear shaft
(captions in the figure: 1 - the input shaft of even gears; 2 - the pressure plate; 3 - the driven disk; 4 - the master disk).
Like any robotic gearbox, a dual-clutch unit has much in common with traditional mechanics. Unless there are twice as many primary and secondary shafts. The gears are engaged in the same way - by connecting the synchronizing slip clutch with the gear ring gear. Only the steps for the driver switch the hydraulic cylinders that move the forks of the transmission forks. Each fork is equipped with a sensor to determine its exact position.
The electro-hydraulic unit, hidden in the crankcase, combines most of the control elements. Almost all valves, sensors, pressure regulators and spools are assembled here, which significantly reduces the number of connectors and simplifies assembly. Moreover, during operation, the characteristics of the nodes change (for example, discs wear out, oil is aging), and the unit is constantly adjusted to the operating conditions so that the switching remains smooth and timely.
The lubrication system of double-clutch gearboxes not only reduces wear on rubbing surfaces, but also removes heat from multi-plate clutches (naturally, this is a case with “wet” clutch gearboxes). For their cooling, a separate circuit with a radiator is provided. The pressure regulator, taking into account the temperature of the lubricant, adjusts the performance of the system. The hotter the oil leaving the couplings, the higher the pressure in the circuit and the more intensive the cooling. In a critical situation, the engine control unit even reduces the fuel supply to reduce the load on the box. If this does not help, the oil supply to the couplings is stopped and the discs open - the box requires you to leave it alone for a while. Situations when the robot is completely out of order are quite rare. Even if one of the sensors breaks down, the unit simply goes into emergency mode (the corresponding series of gears is switched off, the car moves at the remaining two or three speeds) so that the car can get to the service on its own.
