closely watched new FAW Toyota Prado than May 19, 2010 in Chengdu FAW Toyota Motor Corporation plant off the assembly line, the new model increases the luggage rack, rear window can be opened separately, more practical vehicle. The car is still using 1GR 4.0 L engine type, matching a 6-speed manual transmission, 5-speed automatic transmission and the 5-speed manual transmission is improved. In the chassis, the car uses an improved all-wheel drive and KDSS (Dynamic Kinetic suspension system), so that its performance is more prominent chassis. For the convenience of the readers of these two systems to understand, here we have a brief introduction to them.
a, all-wheel drive system
Prado all-wheel drive all vehicles are equipped with a full-time second speed VF4BM type splitter and non-uniform distribution center differential torque (TORSEN LSD), using low friction splitter gear oil, by reducing its viscosity to improve the fuel economy of the vehicle.
1. Mechanical System
(1) splitter
VF4BM technical parameters such as type of splitter (Table 1).
Table 1
(2) center differential (TORSEN LSD)
[ 123] ① structures
FIG 1
is mainly composed of a central differential of the differential housing, a ring gear sets , a ring gear, pinion gears 8, a sun gear hub gear, sun gear and planet gear frame assembly (FIG. 1), as elements thereof an exploded view (FIG. 2).
FIG. 2
② power transmission control
by the center differential the drive torque generated in proportion to a torque limited slip, and automatically change the front and rear wheel torque pointsWith the ratio of front and rear wheels to prevent slipping. When the vehicle is traveling straight, the front and rear torque distribution ratio is set to 41:59, to improve handling of the initial stage of turning; traveling acceleration when the vehicle turns, the torque distribution ratio is set to 30:70, to make steering (Table 2).
Table 2
a. Straight with
When the vehicle is running straight , there is no difference in rotational speed between the sun gear and the ring gear, Accordingly, since the gear turning radius difference, determines the torque distribution ratio of 41:59 before and after (FIG. 3).
FIG. 3
b. Cornering (acceleration state)
When when the vehicle is cornering acceleration, the rotational speed of the sun gear and the ring gear rotation speed are different, the pinion gear starts rotation. At this time, generated between the pinion gear and the planet carrier bore friction, this friction prevents rotation of the pinion gear is rotated while causing the low speed side, so that the high-speed gear-side rotation speed slows down while the power is allocated to the low-speed side (FIG. 4) .
Figure 4
When the vehicle turns, the sun gear rotates faster than the ring gear, once the speed poor, due to the work of LSD, drive torque instantly changed to 30:70. The current rear wheel speed difference is present when, if a case where the front wheel fast speed, the pinion starts to rotate and a frictional force is applied to the carrier, the braking force and the helical gear slip forces, acting respectively on the front side of the ring gear, the pinion The sun gear and the rear side of the back side. Would apply pressure to the clutch gears slip clutch torque by the high speed and low speed side focused new assignment.
When
c. Into the operating time of the rear wheel slip (the accelerated state)
The current rear wheel speed difference, when the front wheel rotation speed fast in the case where the pinion starts to rotate and a frictional force is applied to the carrier, the braking force and the helical gear slip forces, acting respectively, the pinion gear and the rear sun gear rear side of the front ring gear. (FIG. 5) the teethWould apply pressure to the clutch wheel slip, the clutch torque by the high speed and low speed side focused new assignment.
Figure 5
The sun gear rotates faster than the ring gear, the rotational speed difference is generated once, since LSD It activated, to change the driving torque distribution of 53:47. Applying pressure to slide the clutch gear, the clutch as a torque distribution transmitted to the low-speed side.
③ control means
The control device comprises a center differential splitter actuator, the center differential lock and limit switches HL shift limit switch (FIG. 6).
FIG. 6
a. Splitter actuator
As a result of a splitter actuator, such that conversion and splitter gear center differential lock motor control mode changed.
B. Central differential lock limit switch
Central differential lock stopper the internal structure of the switch (FIG. 7), the contact is detected motor position contacting the protrusion.
FIG. 7
cH-L shift limit switch
of HL shift limit switch positioned below the center differential lock limit switch and the driving gear, and its basic structure and operation of the center differential lock limit switch same.
2. The control system
(1) elements
The main element of the splitter comprises a low-speed four-wheel drive control system lights, the center differential lock indicator, VSC OFF indicator, the combination meter assembly, the center differential lock switch, splitter switch position, all-wheelA drive control unit, ECM and splitter shift actuators.
(2) Control Principle
sub-actuator control system as a schematic diagram (FIG. 8).
Figure 8
Second, the dynamic suspension system dynamics (KDSS)
[ 123] 1. Structures
KDSS Prado employed include new front stabilizer, front stabilizer control cylinder, the stabilizer bar, the stabilizer control cylinder, stabilizer control valves, pressure accumulator, stabilizer control unit, a main body control unit, the power control unit, the yaw rate and acceleration sensors, actuators and the like with non-slip indicator KDSS control unit.
2. KDSS control theory
Figure 9
The control principle KDSS (FIG. 9). Fail-safe function when the control unit detects the failure of the stabilizer bar, the run will be displayed in the following table (Table 3)
Table 3
3. The schematic diagram of the hydraulic system
FIG. 10
KDSS as a hydraulic system schematic (FIG. ) 10 shown in FIG. In this hydraulic system, a control valve assembly comprising a stabilizer bar, the pressure accumulator and the accumulator pressure sensor. In the stabilizer control valve assembly, the front and rear stabilizer bars control valve controlling flow between the stabilizer bars control the pump cylinder chamber and the accumulator, the oil fill opening for filling, closing valve for switching the venting line. There accumulator itself nitrogen 2.1 MPa, the accumulator pressure sensor for monitoring the pressure in the hydraulic circuit to protect the values of the components.
4. The operation of the stabilizer bar
FIG. 11
The current control cylinder does not move when the stabilizer bar, the stabilizer bar is twisted; current stabilizer control cylinder is not fixed, the control cylinder due to movement of the stabilizer bar is not twisted or moved (FIG. 11) occurs .
12
When the vehicle has a tendency to roll, front stabilizer hydraulic control cylinder and a rear stabilizer bar conflicting control cylinder, so all the control cylinder is fixed, as each stabilizer bar and the stabilizer bar is twisted normal; when the wheel is in the elevation / falling state, the front and rear stabilizer bars control cylinder will thus move in opposite directions no hydraulic conflict, and therefore, the function of the stabilizer bars is canceled (FIG. 12).
(Wang Yan)