KR20080016213A - Method of controlling a direct connection of the reduction for an automatic transmission in a vehicle - Google Patents

Abstract

A method for controlling a speed reducing process for an automatic transmission is provided to reduce pumping loss by performing the speed reducing process in consideration of inertia energy. A vehicle speed is compared with a first set speed and an air increase control process or an air decrease control process is performed according to the compared result(16,17,19). The vehicle speed is compared with a second set speed and the air decrease control process or the air increase control process is performed according to the compared result(18,19,17). An acceleration position sensor value is compared with a set value and a speed reducing process is performed according to the compared result(20,22). The acceleration position sensor value is compared with the set value and the speed reducing process or the air decrease control process is performed according to the compared result(21,19).

Description

Method of controlling a direct connection of the reduction for an automatic transmission in a vehicle}

1 is a flowchart showing a method for directly controlling deceleration of an automatic transmission according to the prior art;

FIG. 2 is a diagram for explaining derivation of a formula for considering an inertial energy according to a driving of a vehicle; FIG.

3 is a flowchart illustrating a method for directly controlling deceleration of an automatic transmission according to the present invention.

The present invention relates to a method for directly controlling deceleration of an automatic transmission, and more particularly, to a method for directly controlling deceleration of an automatic transmission that can improve fuel efficiency by reducing a pumping loss.

The automatic transmission controls the hydraulic pressure by driving a plurality of solenoid valves according to the traveling speed of the vehicle, the opening rate of the throttle valve, and various detection conditions, so that the shift gear of the target shift stage is operated automatically. It is.

In this way, the automatic transmission has elements that are deactivated in the active state and elements that are converted from the deactivated state when the shift to the target shift stage is executed. It is executed by the control of the hydraulic pressure supplied.

As such, an automatic transmission providing convenience of operation consumes a lot of energy due to slip in a torque converter, and thus has a disadvantage in that fuel economy is lowered compared to a manual transmission.

In addition, the reduction in fuel economy is a situation that is heavily constrained by environmental regulations as it emits an exhaust gas containing a large amount of harmful substances.

Therefore, the technology for improving fuel economy has been developed in automatic transmissions and vehicle makers, but until now, fuel efficiency improvement techniques for vehicles equipped with automatic transmissions have focused on optimization of torque converters, optimization of gear ratios and shift patterns, and so on. Etc. There are many limitations in reality.

Accordingly, in a vehicle equipped with a conventional automatic transmission, the damper clutch is directly connected to the engine rotational speed and the input rotational speed of the transmission for the purpose of improving driving comfort and fuel economy. Deceleration direct control logic is applied to keep the same.

The purpose of the deceleration direct control is to make the engine speed equal to the turbine speed in the form of a manual transmission and cut fuel in this state to improve fuel economy.

Normally, the engine control maintains the fuel cut-off speed. In the automatic transmission, when the power off slip occurs, the engine cut is set in a range where the engine stall does not occur due to the sudden fall of the engine speed.

However, if the deceleration direct control is performed, the engine speed decreases slowly, so that the hysteresis of the fuel cut-off speed can be set small, and the fuel cut-off time is also long. It is possible to improve fuel economy by keeping it long.

The deceleration direct control logic by the conventional method will be described with reference to FIG.

First, it is determined whether the deceleration direct connection condition is satisfied in consideration of the cooling water temperature, the transmission oil temperature condition, the current shift stage position, and the vehicle speed condition (step 1).

If the deceleration direct connection condition is satisfied in the above step 1, it is determined whether the acceleration position sensor value (APS) (hereinafter referred to as 'APS') is '0' and if the value is '0', proceed to the next step. Perform 1 again (step 2).

If the APS is '0', it is applied to perform the deceleration dashpot function and the throttle opening degree (TPS) (hereinafter referred to as 'TPS') is fixed (step 3).

Subsequently, the damper clutch control preparation is performed by applying the basic hydraulic pressure (step 4).

Subsequently, it is determined whether the engine speed Ne (hereinafter referred to as 'Ne') is smaller than the turbine speed Nt (hereinafter referred to as 'Nt'), and if the determination result is YES, proceed to the next step. Perform step 4 again (step 5). This step is to prohibit direct connection since a shock occurs when Ne is larger than Nt, and it is possible to start the direct connection when Ne is smaller than the value of Nt.

Then, the damper clutch direct connection is started and the engine fuel off is started (step 6).

Then, it is determined whether the APS is smaller than the threshold value, and if the determination result is YES, the next step is performed, otherwise step 9 is performed (step 7). In this step, if the APS is above a certain value, it is determined that the acceleration is canceled and the fuel is released.

If the determination result in step 7 is YES, it is determined whether the vehicle speed VS is smaller than the threshold value. If the determination result is YES, the next step is performed. Otherwise, step 6 is performed again (step 8). The determination condition of this step is that when the engine speed in the vibration and direct connection state of the vehicle is too low below a certain vehicle speed, starting may be turned off, so deceleration direct connection is not preferable, and direct connection can be released at this time.

If the determination result in step 8 is YES, the damper clutch direct connection is released, engine fuel injection is started, and the deceleration direct connection is completed (step 9).

However, the deceleration direct control logic according to the conventional method mentioned above does not mention the inertial energy according to the running of the vehicle.

As a result of a long time study and test, the inventors have found that the pumping loss can be reduced and fuel economy can be improved by performing deceleration direct control of the automatic transmission in consideration of the inertia energy according to the driving of the vehicle.

Accordingly, an object of the present invention is to provide a method for directly controlling deceleration of an automatic transmission that can improve fuel efficiency through a reduction in pumping loss.

As a technical configuration for achieving the above object, the present invention is a deceleration direct control method of an automatic transmission that performs an engine fuel cutoff by deceleration direct connection, and determines whether the vehicle speed VS is greater than a preset speed. If the result of the determination is YES, perform the air volume increase control; otherwise, perform the air volume decrease control; and after performing the air volume increase control, it is determined whether the vehicle speed is greater than another preset speed. Performing the air volume increase control again; otherwise performing the next step if the acceleration position sensor value is smaller than the preset value after performing the air volume decrease control; otherwise releasing the deceleration direct connection; If the acceleration position sensor value is smaller than the preset value, In addition, if the specified release the deceleration is smaller than the direct air flow to different rates and not comprising the step of performing the reduction control is again characterized by deceleration direct control method of an automatic transmission is configured.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The torque generated in the engine shown in FIG. 2 is as follows. Accessory torque is excluded here.

The torque generated through the combustion process is obtained by subtracting the frictional resistance of the engine itself and the pumping loss, and the engine torque (see Equation 1 below).

Te = Tc-(Tf + Tp)

In calculating the turbine torque transmitted from the engine through the torque converter, since the damping clutch is directly connected, the following equation 2 is satisfied unless the characteristics of the torque converter are reflected.

Te = Tt

The driving force in the wheel is calculated by reflecting the gear ratio and the efficiency of each stage, as shown in Equation 3 below.

Force Wheel = Tt × i × fgr × η ÷ r = Tt × GR × η ÷ r

Here, the gear ratio, efficiency, and tire companion diameter are constants determined by the H / W specification. Therefore, the expressions C and the above equations may be used to obtain Equation 4 below.

Force Wheel = C × Tt = C × Te = C × [Tc-(Tf + Tp)]

The equation of motion of the vehicle is shown in Equation 5 below.

C × [Tc-(Tf + Tp)] = f0 + f2 × V² + M × a

That is, when a = dV / dt and Fuel Cut Off condition, Tc = 0, so that Equation 6 can be obtained.

M × dV / dt =-(f0 + f2 × V²)-C × (Tf + Tp)

In the above equation, the speed change of the vehicle is determined by the driving resistance of the vehicle, the friction torque and the pumping torque of the engine.

The running resistance and the friction torque of the engine are factors that are determined when the vehicle speed is determined, but the pumping torque is a factor that can be changed by the opening of the TPS or the pressure of the intake manifold.

That is, when decelerating to the damping clutch direct connection state and fuel cut off state, if the pumping torque can be reduced, the vehicle may slow down the deceleration degree. In other words, when decelerating with the same inertia force at the same vehicle speed, if the terms related to the pumping loss can be reduced, more distance can be driven in the engine fuel cut off state. That is, fuel economy is improved.

 In the above equation, Ne is engine speed, Te is engine torque, Tc is combustion torque, Tf is friction torque, Tp is pumping torque, Nt is turbine speed, Tr is turbine torque, M is vehicle weight, a is acceleration of car, Vs is the speed of the car, f0 and f2 are the road load coefficients, i is the gear ratio, fgr is the final gear ratio, GR is ix fgr, η is the P / train efficiency and r is the tire radius.

3 is a flowchart illustrating a method for directly controlling deceleration of an automatic transmission according to the present invention. Steps 10 to 15 are substantially the same as steps 1 to 6 described in the conventional control method.

First, it is determined whether the deceleration direct connection condition is satisfied in consideration of the cooling water temperature, the transmission oil temperature condition, the current shift stage position, and the vehicle speed condition (step 10).

If the deceleration direct connection condition is satisfied in step 10 above, it is determined whether the acceleration position sensor value APS is '0', and if the value is '0', proceed to the next step, otherwise perform step 10 again (step 11). ).

If APS is '0', apply to perform deceleration dashpot function and fix throttle opening (TPS) (step 12).

Subsequently, the damper clutch control preparation is performed by applying the basic hydraulic pressure (step 13).

Subsequently, it is determined whether the engine speed Ne is smaller than the turbine speed Nt (hereinafter referred to as 'Nt'), and if the determination result is YES, proceed to the next step, otherwise perform step 13 again ( Step 14). This step is to prohibit direct connection since a shock occurs when Ne is larger than Nt, and it is possible to start the direct connection when Ne is smaller than the value of Nt.

Then, the damper clutch direct connection is started and the engine fuel off is started (step 15).

Then, it is determined whether the vehicle speed VS is greater than the threshold value, and if the determination result is YES, the next step is performed; otherwise, step 19 is performed (step 16). In this step, it is determined whether the pumping loss reduction control logic is applicable, and the pumping loss reduction control is performed at a predetermined vehicle speed or more.

If the determination result in step 16 is YES, the air volume increase control step (step 17) is performed. In this step, for ECT vehicles, the throttle is increased / maintained by a constant slope up to a certain degree, and in the case of a mechanical throttle, it is increased / maintained by a constant slope up to a certain ISA duty. The reason for maintaining after increasing to a certain slope is to prevent a sudden change in deceleration.

Subsequently, it is determined whether VS is greater than threshold 2, and if the determination result is YES, the next step is performed; otherwise, step 17 is performed again (step 18). This step determines whether the pumping loss reduction control logic is ready to stop, and stops the pumping loss reduction logic below a certain vehicle speed condition.

If the determination edge in step 18 is YES, an air volume reduction control step (step 19) is performed. In this stage, for ECT vehicles, the throttle is reduced / maintained to a certain degree up to a certain degree, and for mechanical throttles, it is reduced / maintained to a certain degree up to a certain ISA duty. The reason for maintaining after reducing to a certain slope is to prevent a sudden change in deceleration.

Then, it is determined whether the APS is smaller than the threshold value, and if the determination result is YES, the next step is performed; otherwise, step 22 is performed (step 20). In this step, if the APS is above a certain value, it is determined that the acceleration is canceled and the fuel is released.

If the determination result of step 20 is YES, it is determined whether the vehicle speed VS is smaller than the threshold value, and if the determination result is YES, the next step is performed; otherwise, step 19 is performed again (step 21). The determination condition of this step is that deceleration direct connection is not preferable because the start may be turned off when the engine speed in the vibration and direct connection state of the vehicle is too low at a certain vehicle speed or less, so that the direct connection is released and fuel injection is performed. do.

If the determination result in step 21 is YES, the damper clutch direct connection is released, engine fuel injection is started, and the deceleration direct connection is completed (step 22).

As described above, the present invention proposes how to efficiently use the inertial energy of the vehicle as compared with the prior art.

As described in the equation using vehicle dynamics, the engine deceleration is reduced by reducing the pumping loss of the engine.

In other words, the pumping loss can be reduced if the engine speed exceeds a certain speed, and the engine loss can be reduced by increasing the throttle opening for the ETC vehicle and increasing the ISA opening for the mechanical throttle. Can be. As the pumping loss decreases, the deceleration of the vehicle decreases, allowing more distance to be traveled in the same vehicle speed.

In addition, in the present invention, when the amount of air in the fuel cut-off state increases, the throttle and ISA are reduced when the vehicle speed reaches a certain vehicle speed to prevent shock due to the rotational flare due to the large amount of air when the fuel is re-injected. By reducing the side effects of the pumping loss reduction logic during the fuel cut-off.

As described above, according to the method for directly controlling the deceleration of the automatic transmission according to the present invention, the pumping loss is reduced by performing the deceleration direct control of the automatic transmission in consideration of the inertia energy according to the driving of the vehicle, thereby improving fuel efficiency. Has the effect.

Claims (3)

As a deceleration direct control method of an automatic transmission that performs engine fuel cutoff by deceleration direct connection, Determining whether the vehicle speed VS is greater than a preset speed, and if the determination result is YES, performing air volume increase control, otherwise performing air volume decrease control; Determining whether the vehicle speed is greater than another preset speed after performing the air volume increasing control, and if the determination result is YES, performing air volume reducing control, otherwise performing air volume increasing control again; After performing the air volume reduction control, if the acceleration position sensor value is smaller than the preset value, perform the following steps; otherwise, canceling the deceleration direct connection; If the acceleration position sensor value is smaller than the preset value, deceleration direct connection is performed if the vehicle speed is smaller than another preset speed; otherwise, deceleration direct control is performed; Way. The method of claim 1, wherein the air volume increase control is maintained by increasing the throttle to a certain inclination to a certain opening degree in the case of an ETC vehicle, and increasing and maintaining it at a constant inclination to a constant ISA duty in the case of a mechanical throttle. Deceleration direct control method of the automatic transmission, characterized in that performed. The method of claim 1, wherein the air volume reduction control is performed by reducing and maintaining the throttle to a certain inclination to a certain opening degree in the case of an ETC vehicle, and decreasing and maintaining the inclination to a constant ISA duty in the case of a mechanical throttle. Deceleration direct control method of the automatic transmission, characterized in that performed.

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