KR100418662B1 - Method for preventing overheating of engine of vehicle with automatic transmission - Google Patents

Abstract

PURPOSE: A method for preventing the overheating of an engine of a vehicle with an automatic transmission is provided to prevent the temperature of coolant from rising and to maximally reduce the loss of power by fixing a gear level at 3-speed with a TCU(Transmission Control Unit) and directly connecting the engine with a planetary gear device by operating a lockup clutch when the temperature of coolant is over 100 deg.C. CONSTITUTION: A method for preventing the overheating of an engine of a vehicle with an automatic transmission is composed of steps for inputting the temperature of coolant detected by an ECU(Electronic Control Unit)(ST1); inputting a gear level to a TCU(ST2); deciding if the coolant temperature is over 100 deg.C(ST3); fixing a gear level at 3-speed with the TCU(ST4); operating a lockup clutch(ST5); and informing a driver of the overheating of the engine by turning on a warning lamp disposed to a meter set with the TCU(ST6). When the lockup clutch is operated, the engine and a planetary gear device are mechanically connected instead of fluid and accordingly the loss of power is maximally decreased by sliding of fluid.

Description

How to Prevent Engine Overheat in Automatic Transmission Vehicles

The present invention relates to a method for preventing engine overheating of an automatic transmission vehicle. More specifically, when the engine is overheated, the method for preventing engine overheating of an automatic transmission vehicle which enables the automatic transmission to be switched to an emergency mode to move the vehicle to the nearest garage. It is about.

In general, automotive engines are designed to operate primarily within the elastic range of the engine, that is, from the rotational speed that generates the maximum rotational force to the rotational speed that produces the maximum power in the engine's performance curve. It requires maximum traction or maximum output of the drive wheels when starting, accelerating and climbing. However, if the transmission ratio is less than 1, that is, when the output shaft rotation speed is the same or higher than the engine rotation speed, the acceleration and climbing ability is greatly reduced. We are converting to the required level. In other words, the transmission converts and transmits the torque and rotational speed of the engine, enables idle movement of the engine when the vehicle is stopped, and reverses by changing the rotation direction of the driving wheel.

Such transmissions can be classified into manual transmissions and automatic transmissions according to the transmission method. In the case of manual transmissions, the driver should shift the vehicle to the appropriate state for the load and the vehicle speed, whereas the automatic transmission has omitted the manual clutch operation mechanism. It is designed to allow the driver to control the driving speed of the vehicle by operating only the accelerator pedal.In addition to the advantages of being easy and comfortable to drive, there are many advantages such as not excessive force or shock being transmitted to the engine or the driving device. The situation is becoming.

As described above, the automatic transmission is generally configured to combine the fluid torque converter and the planetary gear device and to automatically shift according to the operating conditions and the load of the engine by using the hydraulic control device.

A typical four-speed automatic transmission is a fluid torque converter that is connected to the crankshaft of the engine and serves as an oscillating clutch and increases rotational torque. The fluid torque converter is installed next to the fluid torque converter to convert rotational speed and rotational speed. Planetary gear device for changing the direction of rotation, Hydraulic control device for changing and operating the hydraulic gear automatically or manually according to the vehicle speed or driving conditions, Housing and mode surrounding the devices, such as parking, reverse and forward high speed It has a configuration of a selection lever for selecting a mode such as driving.

The fluid torque converter consists of three vanes, a pump impeller, a turbine runner, and a stator. The pump impeller is driven by the crankshaft of the engine, the turbine runner is connected to the transmission input shaft, and the stator is connected to the housing via a one-way clutch. It is equipped with oil inside.

The planetary gear device includes a sun gear, a ring gear, a planetary gear carrier, and a friction actuating element for connecting or securing these gears to a drive or driven shaft. As the friction actuation element, a clutch, a brake and a one-way clutch are used. The friction actuation element is operated by a hydraulic control device to selectively drive, connect or fix the sun gear, the ring gear and the planetary gear carrier. In this case, the rotational speed and the rotational force of the engine inputted through the fluid torque converter are increased or decreased, and in some cases, the rotational direction is changed and transmitted to the longitudinal reduction gear device of the propulsion shaft. Looking at in detail the shifting action according to.

① N range (neutral)

In this range, the power of the input shaft is not transmitted to the output shaft because all the friction actuating elements do not work and the components forming the planetary gear set, that is, the sun gear, the ring gear and the planet gear carrier are free to rotate.

② P range (parking)

This range is functionally the same as the N range in ①, but if the shift lever is set to P range, the parking hole is fitted to the outer gear of the oil distributor and the output shaft is mechanically fixed. The low speed reverse brake acts to fix the rear planetary gear carrier.

③ D range (1 speed status)

In this range, the forward clutch and the one-way clutch work. Therefore, the power is input to the sun gear of the second planetary gear set. At this time, since the planetary gear carrier is fixed by the one-way clutch, the power input to the sun gear is reduced and transmitted to the output shaft through the ring gear carrier.

④ D-Layer (2 speed status)

In this range, the forward clutch and the 2-4 brakes act. Therefore, the power is input to the sun gear of the second planetary gear set. Since the ring gear is in a freely rotating state, the power input to the sun gear is transmitted to the planetary gear carrier, but the sun gear of the first planetary gear set is driven by the first brake. Since it is fixed, it is decelerated at a predetermined speed through its planetary gear carrier and transferred to the ring gear of the second planetary gear set. Here, in the second planetary gear set, there is an input of power through both the sun gear and the ring gear, and the input power is transmitted to the output shaft through the ring gear via the planetary gear carrier. Even in this range, the power is decelerated, but by inputting the sun gear of the second planetary gear set, a speed higher than that of the first speed can be obtained.

⑤ D-Layer (3 speed status)

In this range, the forward clutch and the coasting clutch work. Therefore, power is simultaneously input to the planetary gear carrier of the first planetary gear set and the sun gear of the second planetary gear set. At this time, the power input to the planetary gear carrier of the first planetary gear set is transmitted to the ring gear through the planetary gear carrier because its sun gear and the ring gear are in a free state. Through this power transmission process, the second planetary gear set has power input through the sun gear and the ring gear, so that the second planetary gear set is directly connected to the output shaft as it is directly through the planetary gear carrier without deceleration of the input power. Delivered.

⑥ D-Layer (4 speed status)

In this range, the forward clutch and the 2-4 brakes act. Therefore, power is inputted to the planetary gear carrier of the first planetary gear set. At this time, since the sun gear of the planetary gear set is fixed by the 2-4 stage brake, the power is continuously increased through the ring gear. Since the power output through the ring gear is in a state in which the sun gear and the ring gear of the second planetary gear set can rotate freely, the power is transmitted from the first planetary gear set to the output shaft without increasing or decelerating the power. It is an overdrive.

⑦ R lazy (reverse)

In this range, the reverse clutch and the low speed and reverse brake act. The power is thus input to the sun gear of the first planetary gear set. At this time, since the planetary gear carrier is fixed by the low speed and reverse brake, the power input to the sun gear is transferred to the output shaft through the ring gear in a decelerated state. Therefore, the reverse drive state is reversed.

As described above, the shift operation of combining the respective speed stages by operating the respective clutches and the brakes is performed by the hydraulic pressure generated by the oil pump. That is, the automatic transmission is a device for controlling the hydraulic pressure according to the driving speed of the vehicle, the engine load, and the position of the shift lever, and a transmission control unit (TCU: Electronic Control) that electronically controls the operation of the hydraulic control device. Hereinafter referred to as TCU).

The TCU receives the information on the throttle valve opening angle and the coolant temperature from an electronic control unit (ECU), which is mainly used for engine control, and controls each device of the automatic transmission.

However, when the engine is overheated due to engine failure or lack of coolant, the driver has no idea how to deal with it, and while driving as it is, the engine is completely broken, and the vehicle is often damaged by stopping the broken vehicle on the road.

Accordingly, an object of the present invention is to provide a method for preventing engine overheating of an automatic transmission vehicle that can move the vehicle to an adjacent repair shop so that the engine does not overheat any more when the engine is overheated.

1 is a flowchart sequentially showing a method for preventing engine overheating according to the present invention.

In order to achieve the above object, the present invention, if the cooling water temperature transmitted from the electronic control unit to the transmission control unit is 100 ℃ or more, the transmission control unit operates the lock-up clutch while fixing the speed change stage at three speeds, The lock-up clutch mechanically connects the engine and the planetary gear unit to minimize the power loss due to the sliding of the fluid while the cooling water temperature no longer rises, and at the same time, the transmission control unit lights a warning light provided in the meter set. It is characterized by.

According to the configuration of the present invention described above, when the temperature of the cooling water temperature is 100 ℃ or more, the transmission control unit operates the lock-up clutch while fixing the shift stage at three speeds, thereby mechanically connecting the engine and the planetary gear device directly, The temperature of the engine is no longer raised while minimizing the loss of the driving force, and thus the vehicle can be moved to the adjacent workshop in this state.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

EXAMPLE

1 is a flowchart sequentially illustrating a method for preventing engine overheating according to the present invention.

For reference, in the description of the configuration of the present embodiment, the same parts as in the prior art described at the beginning of the specification are omitted and repeated descriptions are mainly described in order to avoid duplication of description. use.

As shown, the coolant temperature sensed by the ECU in step ST1 is input to the TCU, and in step ST2, the speed change stage is input to the TCU.

Then, in step ST3, when the cooling water temperature becomes 100 DEG C or more, in step ST4, the TCU fixes the shift stage at three speeds, and in step ST5, the lock-up clutch is operated.

Here, the reason why the shift stage is fixed at the third speed instead of the first speed or the second speed is because the first speed or the second speed increases the engine temperature because the driving force is too large and the engine rotation speed is increased. This is because the vehicle cannot be moved to an adjacent garage.

In addition, the lock-up clutch mechanically connects the engine and the planetary gear unit, thereby eliminating the loss due to the sliding of the fluid, and improving fuel efficiency and quietness. When the lock-up clutch is operated as in step ST5, the engine and the planetary Since the gear device is mechanically connected rather than fluid, it is possible to minimize the power loss due to the sliding of the fluid.

In addition, when the above situation occurs, in step ST6, the TCU simultaneously lights up the warning light provided in the meter set, thereby informing the driver that the engine is currently overheated.

According to the present invention as described above, when the cooling water temperature is 100 ℃ or more, the TCU is fixed to the three-speed shift stage and operating the lock-up clutch to directly connect the engine and the planetary gear device, the cooling water temperature further rises Power loss can be reduced as much as possible while the vehicle is not in operation, allowing the vehicle to be moved quickly to adjacent workshops.

On the other hand, the present invention is not limited to the above-described specific preferred embodiments, and various changes can be made by those skilled in the art without departing from the gist of the invention claimed in the claims. will be.

Claims (1)

If the coolant temperature transmitted from the electronic control unit to the transmission control unit is 100 ° C or higher, the transmission control unit operates the lock-up clutch while fixing the shift stage at three speeds, and the lock-up clutch operates the engine and the planetary gear unit. To reduce the power loss due to the sliding of the fluid while the cooling water temperature does not rise any more, and at the same time, the transmission control unit lights the warning lamp provided in the meter set. .