KR102605822B1 - Method of Controlling Transmission Line Pressure of Hybrid Vehicle - Google Patents

Abstract

The method for controlling the transmission line pressure of a hybrid vehicle of the present invention is to determine the actual turbine speed and the current gear stage for each torque area while satisfying the APS (Accelerator Position Stroke) condition, torque condition, and ATF (Auto Transmission Fluid) temperature condition when the transmission is in gear. The absolute value of the speed difference value of the target speed is compared with the set value, and in the torque area where the absolute value of the speed difference value is greater than the set value, the learning value is acquired through line pressure lowering control and stored and used, while in the large and small area, the motor By allowing the line pressure to be raised through rotation speed correction, fuel efficiency is improved by reducing pump loss through turbine speed control through motor intervention. In particular, while the motor rotation speed control lowers the line pressure, the turbine speed and target stage speed are improved. By controlling the target speed so that it does not deviate, the transmission line pressure is lowered to the minimum through learning.

Description

{Method of Controlling Transmission Line Pressure of Hybrid Vehicle}

The present invention relates to transmission control of a hybrid vehicle, and in particular, in a hybrid vehicle (TMED), a transmission line pressure control method of a hybrid vehicle that improves fuel efficiency by lowering the line pressure through learning using the characteristics of turbine speed control by motor intervention. It's about.

In general, a vehicle's transmission line pressure is a major factor in improving fuel efficiency, but transmission line pressure control for this purpose is controlled only to the initially set value because the transmission line pressure is fixed to one value.

Therefore, if the transmission line pressure can be lowered even slightly from the initial setting value, fuel efficiency can be improved, but the slip caused by the difference between the turbine speed and the target stage speed at low transmission line pressure is hardware (H/ There is a limit to lowering the transmission line pressure in internal combustion engine vehicles and hybrid vehicles by causing major problems with W).

For example, in an internal combustion engine vehicle, transmission line pressure control sets the line pressure as a vehicle speed and torque axis with fixed values, and a safety factor that reflects the characteristic of there being no element that can control the turbine speed of the transmission is set by the hardware. Prevent slip from occurring by setting it higher than the (H/W) setting value.

In addition, hybrid vehicles have the characteristic of controlling the turbine speed by intervening the motor, but slip is prevented by using a high fixed line pressure.

Japanese registered patent JP 6150036 B2 (2017.06.02)

However, hybrid vehicles have the characteristic that the fixed line pressure can be lowered even slightly by controlling the turbine speed by motor intervention, but this does not reflect the deviation of the vehicle from this characteristic, and the fixed line pressure is applied as the initial setting value, improving fuel efficiency. This possible advantage is not realized.

Accordingly, taking the above into account, the present invention improves fuel efficiency by reducing pump loss by lowering line pressure by utilizing the characteristics of turbine speed control by motor intervention, and in particular, motor intervention is required to lower line pressure to improve fuel efficiency. Transmission line pressure control for hybrid vehicles that can lower the transmission line pressure to the minimum through learning by controlling the motor to the target speed so that the turbine speed and target speed do not deviate from the target speed while lowering the line pressure by using the characteristics of turbine speed control. The purpose is to provide a method.

The transmission line pressure control method of a hybrid vehicle of the present invention for achieving the above object includes the steps of entering line pressure variable control when the transmission is in gear; A step of determining whether to learn line pressure for the line pressure variable control for each torque region; And it is characterized in that it is performed in a step in which line pressure is lowered or line pressure is increased depending on the torque area.

In a preferred embodiment, one or more of APS conditions, torque conditions, and ATF temperature conditions are applied as entry conditions for the line pressure variable control.

In a preferred embodiment, the determination of whether to learn the line pressure is made based on the absolute value of the speed difference value obtained by subtracting the current gear stage target speed from the actual turbine speed, and then the absolute value of the speed difference value is compared with a set value, and the speed difference A torque range whose absolute value is greater than the set value is applied to the line pressure downward, while a smaller torque range is applied to the line pressure upward.

In a preferred embodiment, the line pressure lowering is a step of matching the actual turbine speed, which is higher than the current gear target speed, with the current gear target speed by controlling the rotation speed of the motor, and the actual turbine speed and the current gear target target. This is performed by setting the speed match as a learning value, and storing and utilizing the learning value.

In a preferred embodiment, the rotation speed of the motor is controlled so that the line pressure gradually decreases, and the learning value is stored using a storage area for each torque area.

In a preferred embodiment, the line pressure is increased by adjusting the target speed of the current gear stage through rotation speed correction control of the motor, and adjusting the actual turbine speed lower than the target speed of the current gear stage by controlling the rotation speed of the current gear stage. It is performed in the step of matching the target speed, and the rotation speed correction of the motor is controlled to gradually increase the line pressure.

In a preferred embodiment, the transmission is TMED.

The transmission line pressure control method applied to the hybrid vehicle of the present invention implements the following actions and effects.

First, line pressure control can be achieved with variable line pressure by learning the transmission line pressure by controlling the turbine speed of the motor. Second, even if a fixed line pressure is used that takes into account slip, which can cause damage to hardware (H/W), the pump loss is reduced and fuel efficiency is improved by being controlled to lower the line pressure to the target speed of the motor. . Third, the problem of using a fixed line pressure despite the existence of vehicle variation is resolved. Fourth, the line pressure learning concept can be implemented by controlling the turbine rotation speed of the motor of a hybrid vehicle. Fifth, by lowering the transmission line pressure, the fuel efficiency improvement effect can be greatly increased by the lowered line pressure.

FIG. 1 is a flowchart of a method for controlling transmission line pressure of a hybrid vehicle according to the present invention, and FIG. 2 is an example of a line pressure downward learning torque area according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached illustration drawings. These embodiments are examples and may be implemented in various different forms by those skilled in the art to which the present invention pertains, so they are described herein. It is not limited to the embodiment. In addition, hybrid vehicles and TMED-type hybrid vehicles that do not typically have a torque converter are expressed as turbine speed control by motor intervention in the same way as hybrid vehicles.
Therefore, in the following, just as the shift control of a hybrid vehicle equipped with a torque converter is expressed as turbine speed control by motor intervention, the turbine speed control by motor intervention, which is shift control, is also discussed in a TMED type hybrid vehicle without a torque converter. It is clear that this should be understood by customary use of the term actual turbine speed of the transmission turbine 1. In other words, the actual turbine speed of the transmission turbine 1 is merely a technical term introduced to conventionally express the speed of the transmission input shaft as 'turbine speed' in a TMED type hybrid vehicle not equipped with a torque converter.

Referring to FIG. 1, the method of controlling the transmission line pressure of a hybrid vehicle involves entering the line pressure learning torque area confirmation step (S30) through the transmission line pressure variable entry step (S10 to S20) and then controlling the line pressure downward according to the torque region. It is implemented as a step (S40) or a line pressure upward control step (S50). In this case, the hybrid electric vehicle is a TMED (Transmission Mounted Electric Device) type vehicle, and each stage of transmission line pressure control is controlled by the TCU (Transmission Control Unit) and stored through memory or control map, and the transmission turbine speed Controls the rotation speed of the motor for adjustment.

Therefore, the transmission line pressure control method of the hybrid vehicle applies the turbine rotation speed control characteristics of the motor as a transmission line pressure learning concept, reducing pump loss by lowering the high line pressure ignoring vehicle deviation to the target speed. A significant improvement in fuel efficiency can be achieved.

Specifically, the transmission line pressure variable entry (S10 to S20) is performed in the main gear status check step of S10 and the learning condition satisfaction step of S20.

For example, checking the status of the in-gear (S10) means entering the gear shift of the transmission, and since the gear of the transmission is engaged, the in-gear does not enter the transmission line pressure control as in S10-1 when the in-gear is not in the in-gear state. If it is in the in-word state, it enters the learning condition satisfaction stage of S20.

Next, the learning condition satisfaction (S20) applies the APS condition, torque condition, and ATF temperature condition as learning conditions in the in-gear condition. In this case, the APS is not exemplified as a specific APS value because it is the accelerator pedal depression amount (Accelerator Position Stroke) related to the throttle opening amount, and the torque is not exemplified as a specific torque value because it is the torque of the transmission applied to the shift stage according to the main gear. , the ATF (Auto Transmission Fluid) temperature is applied at a normal temperature range of about 100 to 130°C.

As a result, the learning condition satisfaction (S20) confirms the APS condition, torque condition, and ATF temperature condition in the in-gear condition, and if these conditions are not satisfied, transmission line pressure control is not entered like in S20-1, but is satisfied. If this is the case, the process switches to the line pressure learning torque area confirmation stage of S30.

Specifically, the line pressure learning torque area confirmation (S30) is to perform line pressure learning in each torque area. Different torque areas are used to apply learning differently because the line pressure learning values do not match in other torque areas. This is because the in-word status may be released.

To this end, the line pressure learning torque area confirmation (S30) applies the following torque area determination equation.

Torque range judgment formula: |Turbine speed - Target speed of current gear| < Setting value?

Here, “turbine speed” is the actual turbine speed of the transmission turbine (1) detected in the in-gear state, “target speed of the current gear” is the target speed of the current gear stage detected in the in-gear state, and “set value” is the actual turbine speed. This is the allowable difference between the turbine speed and the target speed of the current gear. In this case, the turbine speed, the target speed of the current gear, and the set value are not limited to a specific value because the current gear in the in-gear state is not specified.

As a result, the line pressure learning torque area check (S30) compares the absolute value of the difference between the actual turbine speed and the current gear stage target speed with the set value, and if the absolute value of the difference value is greater than the set value, S40 While it enters the line pressure downward control stage, if it is small, it switches to the line pressure upward control stage of S50.

Specifically, the line pressure lowering control (S40) is performed in the line pressure lowering learning performance step of S41 and the learning value utilization step of S42. On the other hand, the line pressure upward control (S50) is performed in the opposite direction to the line pressure downward control (S40), and is performed in the motor rotation speed control step of S51 and the line pressure upward learning step of S52.

Referring to the torque area diagram of FIG. 2, in the in-gear state, the turbine speed (i.e., actual turbine speed) of the transmission turbine 1 is higher than the target stage speed (i.e., current gear stage target speed). , if the difference value is less than the set value) is applied to the line pressure downward control step (S40), while the opposite state (i.e., if the difference value is greater than the set value) is applied to the line pressure upward control step (S50). .

For example, in the line pressure lowering learning performance (S41), the motor changes the relatively high turbine speed (i.e., actual turbine speed) to a relatively low target speed (i.e., current gear target speed) by controlling the rotation speed down. By matching with , the line pressure can be lowered, and at this time, the motor controls the rotation speed so that the line pressure can be lowered little by little to prevent sudden changes in rotation speed from affecting the transmission durability.

Finally, the learning value utilization (S42) stores the learning value obtained as a result of the line pressure lowering learning performance (S41) in a storage area for each torque and applies it to use it at a later stage to learn line pressure lowering control in the same situation. Apply the value.

Therefore, the line pressure lowering control (S40) stores the learned value of line pressure lowering and then terminates the transmission line pressure control logic of the hybrid vehicle.

On the other hand, in the motor speed control (S51), the motor adjusts the current gear target speed through speed correction control, which is to prevent the turbine from deviating from the current gear target speed when the line pressure is insufficient in the in-gear state. .

Finally, the line pressure upward learning (S52) matches the relatively low turbine speed (i.e., actual turbine speed) with the relatively high target speed (i.e., current gear target speed) by increasing the rotation speed of the motor. The pressure can be raised, and at this time, the motor controls the speed of rotation so that the line pressure is raised little by little to prevent sudden changes in speed from affecting the transmission durability.

Therefore, the line pressure upward control (S50) increases the line pressure and then terminates the transmission line pressure control logic of the hybrid vehicle.

As described above, the method of controlling the transmission line pressure of a hybrid vehicle according to the present embodiment is performed by torque area when the APS (Accelerator Position Stroke) condition, torque condition, and ATF (Auto Transmission Fluid) temperature condition are met when the transmission is in gear. The absolute value of the speed difference value between the actual turbine speed and the current gear target speed is compared with the set value, and in the torque area where the absolute value of the speed difference value is greater than the set value, the learning value is acquired through line pressure downward control and stored for use. On the other hand, by allowing the line pressure to be raised by compensating the motor speed in a small torque area, fuel efficiency is improved by reducing the pump loss through turbine speed control by motor intervention, and in particular, the motor speed control lowers the line pressure. By controlling the target speed to prevent the turbine speed from deviating from the target speed, the transmission line pressure is lowered to the minimum through learning.

1: Transmission turbine

Claims (10)

Entering line pressure variable control when the transmission is in gear;
A step of determining whether to learn line pressure for the line pressure variable control for each torque region; and
A step in which line pressure is lowered or a line pressure is increased depending on the torque area.
A transmission line pressure control method for a hybrid vehicle, characterized in that performed by.
The method of claim 1, wherein the entry condition for the variable line pressure control is one or more of an Accelerator Position Stroke (APS) condition, a torque condition, and an Auto Transmission Fluid (ATF) temperature condition.
The method of claim 1, wherein the determination of whether or not to learn the line pressure is made based on the absolute value of the speed difference value obtained by subtracting the current gear stage target speed from the actual turbine speed.
The method of claim 3, wherein the absolute value of the speed difference value is compared with a set value,
A transmission line pressure control method for a hybrid vehicle, characterized in that a torque region in which the absolute value of the speed difference value is greater than the set value is applied to the line pressure downward, while a small torque region is applied to the line pressure upward.
The method of claim 1, wherein the step of lowering the line pressure is
A step of matching the actual turbine speed, which is higher than the current gear target speed, with the current gear target speed by controlling the rotation speed of the motor, and
Setting the coincidence between the actual turbine speed and the current gear stage target speed as a learning value, and storing and utilizing the learning value.
A transmission line pressure control method for a hybrid vehicle, characterized in that performed by.
The method of claim 5, wherein the rotation speed of the motor is controlled to gradually lower the line pressure.
The method of claim 5, wherein the learning value is stored using a storage area for each torque area.
The method of claim 1, wherein the step of increasing the line pressure is
A step of adjusting the target speed of the current gear stage by controlling the rotation speed of the motor, and
A step of matching the actual turbine speed, which is lower than the current gear stage target speed, with the current gear stage target speed through the rotation speed correction control.
A transmission line pressure control method for a hybrid vehicle, characterized in that performed by.
The method of controlling transmission line pressure of a hybrid vehicle according to claim 8, wherein the rotation speed correction of the motor is controlled to gradually increase the line pressure.
The method of claim 1, wherein the transmission is a Transmission Mounted Electric Device (TMED).

Images