KR20080054491A - An engine rpm control method of automatic transmission vehicle - Google Patents

Abstract

A method for controlling engine revolutions of an automatic transmission in a vehicle is provided to improve the stability of engine idle by minimizing rapid fluctuation of the engine revolutions. It is determined whether a signal of an inhibitor switch is a swift shift state which is a fast shift manipulating state of D->N->R or D->N->R or not. If it is determined as the swift shift state, it is determined whether air-mass compensation control is started or not based on current RPM of a turbine. If the air-mass compensation control is required, a compensation amount is calculated based on the current RPM, and then a throttle position is controlled during a certain time according to the calculated compensation amount.

Description

Engine speed control method of automatic transmission vehicle {AN ENGINE RPM CONTROL METHOD OF AUTOMATIC TRANSMISSION VEHICLE}

1 is a view for explaining a problem according to the prior art,

2 and 3 are views for explaining a conventional idle load compensation,

4 is a view showing an example of improving load responsiveness when operating the shift lever from the N range to the R range immediately after cold start;

5 is a view for explaining a problem in the swift shift operation in the prior art,

6 is a schematic diagram showing a signal transmission state for idle load compensation according to the present invention;

7 is a flowchart illustrating an idle load compensation control process according to the present invention.

<Explanation of symbols for main parts of the drawings>

1: TCU 2: ECU

The present invention relates to a method for controlling the engine speed of an automatic transmission vehicle, and more particularly, in an overshoot and in a swift shift state of a transmission according to a rapid shift operation of D → N → R or D → N → R in an engine idle state. The present invention relates to a method for controlling engine speed of an automatic transmission vehicle capable of minimizing the occurrence of sudden fluctuations in engine RPM such as an under chute.

An automatic transmission applied to a vehicle is a device that automatically shifts to a target shift stage by controlling a hydraulic pressure by driving a plurality of solenoid valves according to a traveling speed, an opening ratio of a throttle valve, and various detection conditions. .

In automatic transmission vehicles, if the shift lever of a vehicle being stopped is located in the forward driving 'D' or the reverse driving 'R' range from the neutral 'N' range according to the driver's willingness to drive, a large amount of load is temporarily applied at the moment of the gear collection. The engine is caught and accordingly a lot of idle air volume is required.

Accordingly, the idle air amount correction is performed for the idle speed control in the electronically controlled throttle torque system.

However, since the amount of air applied to each vehicle is different and the amount of air is different for each cooling water temperature, it is not possible to match the changes between the vehicles. As a result, when the shift lever is switched, as shown in FIG. SHOOT) or ascends after the descent (OVER SHOOT), the transmission feeling of the automatic transmission is lowered, there is a problem that the noise generation is intensified.

1 is a view showing the engine RPM variation when the driver operates the shift lever from the N range to the R range immediately after starting.

Referring to the conventional idle load compensation to improve this problem is as follows.

2 and 3 are diagrams for explaining conventional idle load compensation. First, referring to FIG. 1, the TCU 1 performs a shift end stage and a shift target stage signal, an analog inhibit switch signal, and a shifting signal. Is transmitted to the ECU 2, the ECU 2 is to control the electronic control throttle opening amount and the ignition timing based on these signals.

Referring to the conventional idle load compensation process in more detail with reference to the flow chart of FIG. 2, when the driver operates the shift lever, the ECU 2 outputs each signal including an inhibit switch signal in the form of an analog signal from the TCU 1. In response to the change of the inhibit switch signal and the shift end stage signal (TCU operation control signal), the transmission shift is determined and the cooling water temperature is checked.

Here, it is determined whether a predetermined time has elapsed since the change of the inhibit switch signal, and when a predetermined time elapses, the idle air amount is corrected according to the cooling water temperature (controlling the electronic control throttle opening amount according to the cooling water temperature) to adjust the load correction amount for each cooling water temperature. Control.

Thereafter, when the air amount correction control time elapses, the air amount compensation control ends.

As described above, the engine RPM fluctuations such as an undershoot phenomenon can be improved during the shift shift operation during engine idle by adjusting the load correction application time and the load response correction amount while correcting the air amount according to the cooling water temperature. Immediately after the shift lever is operated from the N range to the R range, a diagram showing an example of improvement in load responsiveness shows that the engine RPM variation is minimized.

On the other hand, when the shift operation such as ND, NR, RN, DN, load responsiveness can be improved by the above-described logic, but in the case of Swift Shift of RD and DR, from load condition to another load condition in an instant. This is a transition process, which is impossible to cope with conventional logic.

For example, when the signal of the analog inhibi- tion switch is extremely short, it is impossible to digitalize it, and thus it is recognized as D range D range and R range R range.

In particular, as the hardware of the transmission is diversified, the restraint time and the release time of the transmission are different, resulting in more various types of problems.

In addition, the turbine RPM is temporarily released while passing the N range (no load condition) momentarily during the R-N-D transition, and the difference in engine RPM variation is very large according to the speed of release and the time maintained by the release.

In the prior art, there is no load response method during the swift shift, i.e., when the shift lever is rapidly shifted to R-D and D-R.

In the automatic transmission, as described above, when the shift to the target shift stage is executed, the automatic transmission has an element which is deactivated in the operating state and an element which is converted into the operating state in the deactivating state. It is executed by the control of the hydraulic pressure supplied to.

This automatic transmission constrains the turbine's output shaft as any of the operating elements of the powertrain are engaged when the shift lever is in the R or D range while stationary, thus keeping the RPM of the turbine at zero. do.

However, when the shift lever is located in the N range, the output of the turbine is output as is through the shaft as any actuating element of the power train is not constraining the output shaft of the turbine.

In this case, when the shift lever is suddenly shifted from R to N to D or vice versa in the stationary state, as shown in FIG. 5, the hydraulic pressure supplied to the operating element coupled to the R range is released by switching to the N range. The turbine output of the torque converter is delivered as it is to the shaft, which causes the turbine RPM to rise, resulting in an RPM overshoot as the turbine RPM rises above the target engine RPM of the engine.

Then, when the conversion from the N range to the D range is made, the output shaft of the turbine is constrained as the hydraulic pressure is supplied to the under clutch, so the turbine RPM is drastically lowered, and thus the engine RPM is The lower chute is lowered according to the lowering to generate an under chute.

As the Peak To Peak increases in the amount of change in the engine RPM due to sudden R-N-D shifting, there is a problem of reducing the operability by causing discomfort to the driver.

In particular, the engine RPM fluctuates immediately after cold start, which causes problems such as deterioration of operability and fear of sudden start.

Figure 5 is a graph showing the measurement of the engine RPM fluctuations during the RD shift, a very fast shift lever in the form of scraping from the R range to the D range, the customer's quality requirements are increasingly difficult to consider in terms of merchandise. Part.

Accordingly, the present invention has been invented to solve the above problems, such as overshoot and undershoot in a transmission swift shift state according to a rapid shift operation of D → N → R or D → N → R in an engine idle state. An object of the present invention is to provide an engine speed control method of an automatic transmission vehicle that can minimize the occurrence of sudden fluctuations in the engine RPM.

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

The present invention for achieving the above object, in the process of controlling the engine speed during the operation of the shift lever in the engine idle state of the automatic transmission vehicle, D → N → R or D → N → R sudden change from the inhibit switch signal Determining whether a swift shift state is a quick operation state; Determining whether and when to initiate air volume compensation control by referring to the current turbine RPM when it is determined that the swift shift state; Here, if it is determined that the air volume compensation control is necessary with reference to the turbine RPM, calculating a correction amount with reference to the current engine RPM, and controlling the air amount compensation for a predetermined time according to the calculated correction amount, and performing air amount compensation control. Characterized in that.

Here, in the swift shift determination step, the N range holding time is detected from the inhibit switch signal, and if the N range holding time is a sudden shift operation state that is less than a set time, the swift shift state is characterized in that it is determined.

In addition, when the change rate of the turbine RPM exceeds a set value in the step of determining whether or not to start the air volume compensation control, characterized in that to start the air volume compensation control.

In addition, the correction amount is characterized in that it is calculated from the difference between the target engine RPM and the current actual engine RPM.

In addition, the amount of air is reduced by reducing the amount of throttle opening according to the correction amount calculated in the step of performing the air amount compensation control.

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

The present invention is a control method for the load response when operating the shift lever in the engine idle state, the ECU (2) in the engine idle state of the transmission according to the rapid shift operation of the driver D → N → R or D → N → R In the case of the swift shift state by determining the swift shift state, the load response is made by using a control variable different from the normal shift (D↔N or R↔N) state.

In particular, in the present invention, when the N holding time (retention time) is short at R → N or D → N with reference to the inhibit switch signal and the turbine RPM, it is determined as a swift shift mode, and the compensation point is referred to by referring to the turbine RPM rising rate. After deciding, the amount of electronic control throttle opening is reduced for a certain time to reduce the air volume, and the control for ignition timing compensation is performed to cope with the small engine RPM variation.

6 is a schematic diagram illustrating a signal transmission state for idle load compensation according to the present invention, and FIG. 7 is a flowchart illustrating a process for controlling idle load compensation according to the present invention.

As shown in FIG. 6, the ECU 2 receives the shift end stage and the shift target stage signal, the analog inhibit switch signal, and the shifting signal to the TCU 1, and in particular, performs the idle load compensation of the present invention. In order for the ECU 2 to receive the turbine RPM signal is used as a control variable.

In this process, when the ECU 2 determines the normal shift (D↔N or R↔N) state, the ECU 2 performs the throttle opening amount and the ignition timing control in the normal shift mode as in the prior art. When the shift status (D → N → R or D → N → R sudden shift operation state) is determined, the throttle opening amount and ignition timing control is performed according to the new logic using the turbine RPM as a control variable.

Referring to FIG. 7, the idle load compensation control process of the present invention will be described in more detail. First, when the driver operates the shift lever immediately after starting or in a vehicle idling state, the ECU 2 is received from the TCU 1. On the basis of the bit switch signal, the shift state of D → N → R or D → N → R is recognized, and if the holding time of the N range is less than a predetermined time in this process, it is determined as a swift shift state and The control process is performed.

If the swift shift condition is not satisfied, it is determined as a normal shift state (N↔R or N↔D) to perform the same control process as the conventional one. do.

In the swift shift mode, when the rate of change (ΔNt / Δt, Nt / dt) of the turbine RPM (Nt) with respect to the time (t) exceeds a preset reference value, the throttle opening amount is controlled to perform air volume compensation control.

As described above, in the present invention, the rate of change of the turbine RPM (Nt) is used as a reference for determining the load correction control timing. When the rate of change of the turbine RPM exceeds the reference value, the load compensation control is started.

In the air volume compensation control process (load compensation control process), the air compensation amount varies depending on the actual engine RPM change relative to the target engine RPM, and if the amount to be increased compared to the target engine RPM is large, it is rapidly reduced and if it is small, the engine RPM is stably reduced. To secure.

That is, the correction amount in the swift mode is a value calculated by using the difference between the target engine RPM and the actual engine RPM as a variable, and may be defined as 'Swift correction amount = F (target engine RPM-actual engine RPM)', It is calculated according to the value, but if the amount of change in the difference is large, it is set to be reduced quickly.

As described above, the ignition timing control may be simultaneously performed according to the swift correction amount calculated while the air amount correction control is performed.

Table 1 shows an example of calculating the swift correction amount, the swift correction amount is calculated as a value according to the difference between the target engine RPM and the actual engine RPM.

When the air amount compensation control is started according to the correction amount calculated as described above, the control time is accumulated from the starting point, and then the air amount compensation control is performed to perform the air amount compensation control when the accumulated time exceeds the preset time. Quit all.

As described above, in this way, in the engine idle state, it is determined whether the ECU is in the swift shift state of the transmission according to the sudden shift operation of the driver D → N → R or D → N → R, and the turbine is in the swift shift state. After deciding the compensation point by referring to the rate of increase of RPM, the electronic control throttle opening amount is controlled for a certain period of time to compensate for the air volume, and to control the ignition timing, thereby causing a sudden change in engine RPM such as overshoot and undershoot. It can be minimized.

As a result, according to the present invention, the engine idle stability is improved, and engine start-off phenomenon can be minimized under extreme conditions.

Claims (5)

In the process of controlling the engine speed when operating the shift lever in the engine idle state of the automatic transmission vehicle, Judging from the inhibit switch signal whether it is a Swift shift state of D → N → R or D → N → R rapid shift operation state; Determining whether and when to initiate air volume compensation control by referring to the current turbine RPM when it is determined that the swift shift state; Here, if it is determined that air volume compensation control is necessary with reference to the turbine RPM, calculating a correction amount with reference to the current engine RPM, and controlling the throttle opening amount for a predetermined time according to the calculated correction amount to perform air amount compensation control; Engine speed control method of an automatic transmission vehicle comprising a. The method according to claim 1, In the swift shift determination step, the engine speed control of the automatic transmission vehicle is characterized in that it detects the N range holding time from the inhibit switch signal and determines the swift shift state if the N range holding time is less than the set time. Way. The method according to claim 1, And determining the air volume compensation control when the change rate of the turbine RPM exceeds a set value, and starts to control the air volume compensation. The method according to claim 1, The correction amount is the engine speed control method of the automatic transmission vehicle, characterized in that calculated from the difference between the target engine RPM and the current engine RPM. The method according to claim 1, In the step of performing the air volume compensation control, the engine speed control method of the automatic transmission vehicle, characterized in that to reduce the air amount by reducing the throttle opening amount according to the calculated correction amount.

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