JP2006300171A - Controller of continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller of a continuously variable transmission which can provide a full driving force at a controlled change gear ratio in pressing the accelerator and prevent the load of an engine from increasing as well as the quality of the exhaust gas from worsening under the high load. <P>SOLUTION: In pressing the accelerator for acceleration, the controller of the continuously variable transmission increases and corrects the target input rotational number to the higher side than a characteristic curve β of a regular shift schedule determined by an accelerator opening. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for a continuously variable transmission used in an automobile.

  Conventionally, as a continuously variable transmission (including both a V-belt type continuously variable transmission and a toroidal type continuously variable transmission), for example, there is one described in Patent Document 1, and controls the start of a vehicle. As elements, a torque converter is used, a torque converter function is provided in a starting friction element combining a planetary gear mechanism, a forward clutch, and a reverse brake, and the torque converter is omitted.

In any of these continuously variable transmissions, the vehicle speed and the accelerator opening are detected, and based on the shift schedule (FIG. 10 of Patent Document 1) obtained in advance, from the detected vehicle speed and the accelerator opening, A target input rotational speed (target primary pulley rotational speed) is obtained, and the gear ratio is controlled based on the target input rotational speed.
JP 2003-172445 A

  However, in this case, even when the accelerator is stepped on, the target input rotational speed is calculated according to the shift schedule corresponding to the accelerator opening increased by the accelerator stepping, so that the shift schedule corresponds to the engine power performance. Due to the fact that it cannot be determined solely, there has been a problem in that a sufficient driving force cannot be obtained at the controlled gear ratio, and the engine load increases.

  In addition, when the accelerator is stepped on, the engine outputs according to the load, so the fuel consumption increases, the air-fuel ratio becomes rich at high loads, the exhaust gas quality deteriorates, especially during normal times In a diesel engine that is operated in a leaner direction than the ideal air-fuel ratio, there has been a problem that particulates in the exhaust gas increase.

  An object of the present invention is to solve the above-described problem, and when the accelerator is stepped on, a sufficient driving force can be obtained at a controlled gear ratio, and an increase in engine load can be prevented. In addition, an object of the present invention is to provide a control device for a continuously variable transmission that can prevent the quality of exhaust gas from deteriorating at a high load.

  The control device for continuously variable transmission according to the present invention corrects the target input rotational speed to be higher than the characteristic curve of the normal shift schedule determined by the accelerator opening when the accelerator is depressed for acceleration. It is characterized by doing.

  According to this, when the accelerator is stepped on for acceleration, the target input rotational speed is increased and corrected to be higher than the characteristic curve of the normal shift schedule, and the continuously variable transmission is temporarily shifted to the lower speed ratio. By selecting the state, it is possible to reduce the load on the engine while generating the same driving force. Further, by reducing the load on the engine, it is possible to prevent deterioration of the exhaust gas quality.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 shows a power train of a vehicle having a control device for a continuously variable transmission according to an embodiment of the present invention, together with its control system, and this power train is composed of an engine 1 and a continuously variable transmission 2. .
Although the engine 1 is a gasoline engine, the throttle valve 3 is not mechanically connected to the accelerator pedal 4 operated by the driver, but is separated from the throttle pedal 3 and the throttle valve 5 is electronically controlled by the throttle actuator 5. Eggplant.

The operation amount of the throttle actuator 5 is controlled by an engine controller 22 that responds to a command related to the target throttle opening tTVO determined by the general controller 21 according to the operation of the accelerator pedal 4. The output of the engine 1 is controlled so as to become a value corresponding to the operation of the accelerator pedal 4 in accordance with the target throttle opening tTVO.
The engine controller 22 not only performs the throttle opening control via the throttle actuator 5 but is not shown in the figure, but other fuel injection amount control, fuel cut control, ignition timing, etc. that are necessary for the operation of the engine 1 are not shown. Control shall also be performed.

The continuously variable transmission 2 is a well-known V-belt type continuously variable transmission, and includes a primary pulley 7 that is drive-coupled to the output shaft of the engine 1 via a lock-up torque converter 6, and a secondary pulley 8 that is aligned with the primary pulley 7. And a V-belt 9 spanned between these pulleys.
Then, a differential gear device 11 is drivingly coupled to the secondary pulley 8 via a final drive gear set 10, and a wheel (not shown) is rotationally driven by these.

The speed change operation of the continuously variable transmission 2 is such that, among the flanges forming the V-grooves of the primary pulley 7 and the secondary pulley 8, one movable flange is brought relatively close to the other fixed flange to make the V-groove width. Narrowing the width or conversely increasing the V groove width,
The stroke positions of both movable flanges are determined by the ratio of the primary pulley pressure Ppri and the secondary pulley pressure Psec from the transmission control hydraulic circuit 12.

The transmission control hydraulic circuit 12 includes a step motor 13 as a transmission actuator, and the transmission controller 23 is driven to a step position corresponding to the target transmission ratio tRTO. It is assumed that the continuously variable transmission is made to coincide with the gear ratio tRTO.
The transmission controller 23 further outputs a lockup engagement pressure (Pup) signal corresponding to a lockup capacity (L / Uprs) command determined by the general controller 21 to the shift control hydraulic circuit 12 as will be described later, and shift control is performed. The hydraulic circuit 12 controls the lockup engagement pressure to the torque converter 6 to a value corresponding to this signal, and the torque converter 6 is controlled in a slip control state in which the relative rotation (slip) between the input and output elements is limited, and the torque converter. A lockup state in which the input / output elements are directly connected to each other and a converter state in which these slip limit states are released are also used.

  When the transmission controller 23 obtains the target speed ratio tRTO, the target input speed (target primary pulley speed) is obtained from the throttle opening TVO and the vehicle speed VSP based on the previously obtained speed change line. The target speed ratio tRTO is obtained by dividing the input speed (target primary pulley speed) by the transmission output speed (which can be obtained from the vehicle speed VSP).

  The target throttle opening tTVO command to the engine controller 22 is obtained by the general controller 21 as described above, and the lockup capacity L / Uprs command to the transmission controller 23 is obtained by calculation in the general controller 21.

Therefore, a signal from the accelerator opening sensor 24 that detects the depression amount (accelerator opening) APO of the accelerator pedal 4 is sent to the general controller 21;
A signal from a vehicle speed sensor 25 that detects a vehicle speed VSP from the number of rotations of the wheel;
A signal from the idle switch 26 that is turned on when the accelerator pedal 4 is released (when the accelerator opening APO = 0);
A signal from a throttle opening sensor 27 for detecting the throttle opening TVO of the throttle valve 3;
A signal from the engine rotation sensor 28 for detecting the engine speed Ne (torque converter input speed);
A signal from the turbine rotation sensor 29 for detecting the torque converter output rotation speed (turbine rotation speed) Nt is input.

  Of these signals, the vehicle speed VSP signal and the throttle opening TVO signal from the sensors 25 and 27 are also supplied to the transmission controller 23, and the transmission controller 23 determines the target gear ratio tRTO as described above. Shall also be used.

FIG. 2 is a shift schedule showing the control contents of the continuously variable transmission control device according to one embodiment of the present invention.
As shown in FIG. 2, the horizontal axis is the vehicle speed (km / h), the vertical axis is the target input rotational speed (rpm), and the respective characteristic curves corresponding to the accelerator opening are drawn with broken lines. The higher the accelerator opening is, the more the characteristic curve corresponding thereto is located on the higher target input rotational speed side.

  At the control start point A on the characteristic curve α, if the driver steps on the accelerator with the intention of acceleration, the target input speed is increased with the vehicle speed unchanged, and the two-stage accelerator opening is larger than the characteristic curve α. In the normal control, the target input rotational speed is increased along the characteristic curve β as the vehicle speed increases after the control is shifted to the characteristic curve β on the higher side of the continuously variable transmission according to the present invention. The control of the control device is characterized in that the target input rotational speed is increased and corrected to be higher than the characteristic curve β of the normal shift schedule determined by the accelerator opening. (Equivalent to claim 1)

  According to this, when the accelerator is stepped on for acceleration, the target input rotational speed is increased and corrected to be higher than the characteristic curve of the normal shift schedule, and the continuously variable transmission is temporarily shifted to the lower speed ratio. By selecting the state, it is possible to reduce the load on the engine while generating the same driving force. Further, by reducing the load on the engine, it is possible to prevent deterioration of the exhaust gas quality.

  Further, the engine load is estimated from the accelerator opening, the boost pressure, and the fuel injection amount in accordance with the type of engine connected to the continuously variable transmission, and the estimated engine load is calculated. Calculate according to (Equivalent to claim 2) Of course, the boost pressure is a parameter generated when the engine is a turbo engine.

  According to this, the correction amount in the increase correction can be calculated according to the engine load, and the target input rotational speed is unnecessarily increased when the engine is at a low load, and the engine is at a high load. In some cases, it is possible to prevent the correction amount from being insufficient, and to perform optimal correction.

FIG. 3 is a diagram for calculating the increase correction amount of the target input rotational speed in the control device for the continuously variable transmission according to the embodiment of the present invention. The horizontal axis represents the applied pressure or fuel injection amount, and the vertical axis represents the target input rotational speed correction amount (rpm).
The calculation of the increase correction amount of the target input rotational speed corresponding to the above-described second aspect is performed as follows, for example.
That is, the larger the boost pressure or the fuel injection amount or both, the larger the target input rotational speed correction amount, and the larger the accelerator opening, the larger the target input rotational speed correction amount, and the smaller the accelerator opening. Reduce the target input rotational speed correction amount.

  Further, a ratio of returning the target input rotational speed corrected to the higher side to the target input rotational speed on the characteristic curve of the normal shift schedule (for example, the characteristic curve β in FIG. 2) is connected to the continuously variable transmission. According to the type of engine, a decrease in engine load is estimated from the accelerator opening, the boost pressure, and the fuel injection amount, and calculation is performed according to the estimated decrease in engine load. (Equivalent to claim 3)

  According to this, the control device for continuously variable transmission according to the present invention corrects the target input rotational speed excessively by estimating the decrease in the engine load after correcting the target input rotational speed to increase. After the vehicle speed increases, normal control can be returned to the vehicle while the target input rotational speed is increased and corrected to match the driver's acceleration intention.

FIG. 4 is a diagram for calculating the return ratio of the target input rotational speed to the normal control in the continuously variable transmission control apparatus according to the embodiment of the present invention. The horizontal axis represents the applied pressure or the fuel injection amount, and the vertical axis represents the target input rotational speed return ratio.
The calculation of the return ratio to the normal control of the target input rotational speed corresponding to claim 3 described above is performed as follows, for example.

In other words, the larger the applied pressure and / or fuel injection amount, the smaller the return ratio of the target input speed to normal control, and the larger the accelerator opening, the higher the target input speed return ratio to normal control. The smaller the accelerator opening is, the larger the return ratio of the target input rotational speed to normal control is.
Note that the return ratio is the target input speed on FIG. 2 for returning to the value on the characteristic curve β in the normal shift schedule after increasing the target input speed in FIG. The rate of decrease shall be indicated.

Further, the increase correction of the target input rotational speed when the accelerator is stepped on is limited according to the accelerator opening, the accelerator opening change rate, and the engine speed. (Equivalent to claim 4)
According to this, when the driver's intention to accelerate is low, the target input rotational speed can be prevented from excessively increasing by correcting the target input rotational speed to be unnecessarily increased. By excessively rising, it is possible to prevent the driver from feeling uncomfortable. Furthermore, the unnecessary increase correction of the target input rotational speed can prevent the problem that the engine maintains a high speed and the total exhaust gas amount increases.

FIG. 5 is a diagram for limiting the increase correction of the target input rotational speed in the control device for the continuously variable transmission according to the embodiment of the present invention. The horizontal axis represents the accelerator opening (%), and the vertical axis represents the accelerator opening change rate (%).
The increase correction of the target input rotational speed corresponding to the above-described fourth aspect is limited by the accelerator opening and the accelerator opening change rate, for example, as follows.

  That is, when the accelerator opening is equal to or less than the threshold F, the target input rotational speed increase correction control is performed only in the region where the accelerator opening change rate is equal to or more than the threshold G. In the case of H or less, increase correction control of the target input rotational speed is performed when the relationship between the accelerator opening and the accelerator opening change rate is in a region above the curve γ in the figure. Further, in the region where the accelerator opening is equal to or greater than the threshold value H, the target input rotational speed increase correction control is performed only in the region where the accelerator opening change rate is equal to or greater than the threshold value I.

Further, as shown by the solid line in FIG. 6, the characteristic curves of the shift schedule are set so as to decrease toward the side where the target input rotational speed is lower than the characteristic curve shown by the normal broken line. (Equivalent to claim 5)
FIG. 6 is a shift schedule showing the control contents of the continuously variable transmission control device according to one embodiment of the present invention.
According to this, in the control device for a continuously variable transmission according to the present invention, in order to perform an increase correction of the target input rotation speed in accordance with the driver's intention to accelerate, the respective characteristic curves of the shift schedule are represented with acceleration performance. Even if it is suppressed, drivability does not decrease, so the fuel efficiency of the engine can be improved.

FIG. 7 is a flowchart showing a control flow of the continuously variable transmission control device according to the embodiment of the present invention.
The process starts at S1, and at S2, the accelerator opening is read to determine whether it is equal to or greater than the specified value A, and the read accelerator opening is determined. If the accelerator opening is equal to or greater than the specified value A, the process proceeds to S3, and it is determined whether the accelerator opening change rate is equal to or greater than the specified value B determined in FIG. 5 according to the accelerator opening determined in S2. If the accelerator opening is equal to or greater than the specified value B, the process proceeds to S4. If the conditions of S2 and S3 are not satisfied, the process returns to S2.

  In S4, the engine speed is equal to or less than a specified value C at which the engine speed is too high and reaches the rev limit so that the control according to the present invention cannot be performed. It is determined whether or not the above is satisfied. If these conditions are satisfied, the process proceeds to S5. If not satisfied, the process returns to S2.

  In S5, the target input rotational speed correction amount determined by FIG. 3 is calculated, and the process proceeds to S6. In S6, it is determined whether or not the target input rotational speed that has been increased and corrected has been reached. Proceed to S7, and if not reached, return to S5. Further, in S7, the target input rotational speed return ratio determined by FIG. 4 is calculated, and the process proceeds to S8 to determine whether or not the target input rotational speed of the normal control has been reached. The control of the invention ends.

In addition, this invention is not limited only to the said embodiment, Many deformation | transformation or a change is possible.
For example, FIG. 1 shows a V-belt type continuously variable transmission as the continuously variable transmission, but a toroidal continuously variable transmission may be used.

  The control device for a continuously variable transmission according to the present invention is suitable for use in a continuously variable transmission of an A / T vehicle, and can sufficiently obtain a driving force at a controlled gear ratio when the accelerator is stepped on. In addition, the engine load can be prevented from increasing, and in addition, the exhaust gas quality can be prevented from deteriorating at high loads.

1 is a system configuration diagram showing a power train including a control device for a continuously variable transmission according to an embodiment of the present invention together with its control system. It is a shift schedule which shows the control content of the control apparatus of the continuously variable transmission which becomes one Example of this invention. FIG. 3 is a diagram for calculating an increase correction amount for a target input rotation speed in the control device for a continuously variable transmission according to an embodiment of the present invention. FIG. 6 is a diagram for calculating a return ratio of the target input rotation speed to normal control in the continuously variable transmission control apparatus according to the embodiment of the present invention. FIG. 3 is a diagram for limiting increase correction of a target input rotation speed in a continuously variable transmission control apparatus according to an embodiment of the present invention. It is a shift schedule which shows the control content of the control apparatus of the continuously variable transmission which becomes one Example of this invention. It is a flowchart figure which shows the control flow of the control apparatus of the continuously variable transmission which becomes one Example of this invention.

Explanation of symbols

1 Engine 2 Continuously Variable Transmission 3 Throttle Valve 4 Accelerator Pedal 5 Throttle Actuator 6 Lock-up Torque Converter 7 Primary Pulley 8 Secondary Pulley 9 V Belt 10 Final Drive Gear Set 11 Differential Gear Device 12 Shift Control Hydraulic Circuit 13 Step Motor 21 General Controller 22 Engine controller 23 Transmission controller 24 Accelerator opening sensor 25 Vehicle speed sensor 26 Idle switch 27 Throttle opening sensor 28 Engine rotation sensor 29 Turbine rotation sensor

Claims (5)

  A control device for a continuously variable transmission, wherein when the accelerator is depressed for acceleration, the target input rotational speed is increased and corrected to be higher than the characteristic curve of the normal shift schedule determined by the accelerator opening. .   According to the type of engine connected to the continuously variable transmission, the engine load is estimated from the accelerator opening, the boost pressure, and the fuel injection amount, and the correction amount in the increase correction is determined according to the estimated engine load. The control device for a continuously variable transmission according to claim 1, wherein   Depending on the type of engine connected to the continuously variable transmission, the accelerator opening is adjusted so that the target input speed corrected to the higher side is returned to the target input speed on the characteristic curve of the normal shift schedule. 3. The continuously variable transmission control device according to claim 1, wherein a decrease in the engine load is estimated from the boost pressure and the fuel injection amount, and is calculated according to the estimated decrease in the engine load. .   The increase correction of the target input rotational speed when the accelerator is stepped on is limited according to the accelerator opening, the accelerator opening change rate, and the engine rotational speed. Control device for continuously variable transmission.   The control device for a continuously variable transmission according to any one of claims 1 to 4, wherein each characteristic curve of the shift schedule is set so as to decrease toward a side where the target input rotational speed becomes low.

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