JP2008249017A - Shift control device for continuously variable transmission and shift control method thereof - Google Patents

Abstract

An object of the present invention is to provide a speed change control device for a continuously variable transmission and a speed change control method for a continuously variable transmission capable of reducing a speed change shock and improving acceleration response.
In a transmission control device for a continuously variable transmission that transmits engine output torque to a driving wheel, an ECU 50 estimates a loss torque due to rotational inertia when detecting an accelerator ON, and a loss torque due to the estimated rotational inertia. When the engine compensation torque control for compensating for T _loss is started and the engine output torque T _eg becomes larger than the estimated loss torque T _loss due to the rotational inertia, the continuously variable transmission 30 (hydraulic control device 40) Instruct to start shifting.
[Selection] Figure 1

Description

  The present invention relates to a transmission control device and a transmission control method for a continuously variable transmission, and more particularly to a transmission control device and a transmission control method for a continuously variable transmission that can reduce a shift shock of the continuously variable transmission.

  A continuously variable transmission represented by a belt type continuously variable transmission or a toroidal type continuously variable transmission obtains a target gear ratio from, for example, an engine demand load and a vehicle speed, and shifts so that an actual gear ratio becomes this target gear ratio. Control. Therefore, for example, when the driver depresses the accelerator pedal to increase the required engine load, or when the vehicle speed decreases such that the vehicle speed decreases due to insufficient driving force, the target gear ratio increases (the gear ratio on the low speed side). The continuously variable transmission is downshifted to the increased target gear ratio.

  Such a shift causes a change in the engine speed (engine rotation inertia) with a change in the gear ratio, and an inertia torque with a negative engine torque (rotational inertia) during a downshift that increases the engine speed. Is caused by a reduction in the torque (loss torque), and a shift shock with a feeling of torque pull-in is generated.

  In order to mitigate such a shift shock, for example, in Patent Document 1, an engine torque is calculated so that an inertia torque associated with a shift is calculated from the speed change speed of the continuously variable transmission and the inertia torque is offset. There has been proposed a gear shift shock reduction device for a continuously variable transmission equipped vehicle that corrects the above.

  However, in this document, the inertia torque is canceled by the engine correction torque, but nothing is mentioned about the relationship between the shift and the engine torque correction timing. When the shift is started in a state where the actual engine torque is not sufficiently generated, there is a problem that the vehicle acceleration is lowered and the acceleration response is deteriorated.

Japanese Patent Laid-Open No. 11-20512

  The present invention has been made in view of the above, and provides a transmission control device for a continuously variable transmission and a transmission control method for a continuously variable transmission that can reduce shift shock and improve acceleration response. The purpose is to provide.

  In order to solve the above-described problems and achieve the object of the present invention, the present invention provides a detection means for detecting an accelerator state in a transmission control device for a continuously variable transmission that transmits engine output torque to drive wheels, Loss torque estimation means for estimating a loss torque due to rotational inertia when the accelerator is detected by the detection means, and engine torque control means for starting engine compensation torque control for compensating for the loss torque estimated by the loss torque estimation means And a shift control means for instructing the continuously variable transmission to start shifting when the engine output torque is larger than the estimated loss torque.

  According to a preferred aspect of the present invention, it is desirable that the engine torque control means stops the engine compensation torque control when the shift of the continuously variable transmission is completed.

  In order to solve the above-described problems and achieve the object of the present invention, the present invention provides a detection step of detecting an accelerator state in a continuously variable transmission shift control method for transmitting engine output torque to drive wheels; A loss torque estimation step for estimating a loss torque due to rotational inertia when an accelerator ON is detected in the detection step; an engine torque control step for starting an engine compensation torque control for compensating the estimated loss torque; and the engine output torque. A shift control step of instructing the continuously variable transmission to start shifting when the torque becomes larger than the loss torque.

  According to the present invention, in a speed change control device for a continuously variable transmission that transmits engine output torque to driving wheels, a detection means for detecting an accelerator state, and a loss due to rotational inertia when an accelerator ON is detected by the detection means. Loss torque estimation means for estimating torque, engine torque control means for starting engine compensation torque control for compensating for the loss torque estimated by the loss torque estimation means, and the engine output torque is larger than the estimated loss torque. If the accelerator is turned on, the engine compensation torque control is performed to increase the target engine torque when the accelerator is turned on. By canceling the torque loss due to rotational inertia, the shift shock caused by torque loss due to rotational inertia can be reduced. In addition, when the engine output torque is greater than the loss torque due to the rotation inertia, the shift is started and the shift is performed with the engine output torque being sufficient, so that the acceleration response can be improved. There is an effect.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

  FIG. 1 shows a schematic configuration diagram of a power train of a vehicle to which a shift control device and a shift control method for a continuously variable transmission according to the present invention are applied, and a control system thereof. As shown in FIG. 1, a continuously variable transmission (CVT) 30 is connected to an engine 10 as an internal combustion engine via a torque converter 20. The engine output torque (driving force) of the engine 10 is input to the continuously variable transmission 30 via the torque converter 20 and transmitted to the drive wheels 90 via the differential gear and the drive shaft.

  The continuously variable transmission 30 is configured by a known belt-type continuously variable transmission, and is provided on the engine side. A primary pulley 31 connected to the output shaft 70 of the torque converter 20 and an output shaft connected to a differential gear. A secondary pulley 32 connected to 80 and a belt 33 stretched between them are provided. The hydraulic control device 40 changes the gear ratio of the continuously variable transmission 30 in accordance with a gear ratio change command input from the ECU 50. The hydraulic control device 40 can change the pulley ratio steplessly by adjusting the transmission pressure to the primary pulley side actuator and the line pressure to the secondary pulley side actuator to change the pulley ratio.

The continuously variable transmission 30 includes a primary pulley rotation sensor 34 that detects the rotation speed (primary rotation speed) N _pri of the primary pulley 31 and a secondary that detects the rotation speed (secondary rotation speed) N _sec of the secondary pulley 32. A pulley rotation sensor 35 is provided, and the detected primary rotation speed N _pri and secondary rotation speed N _sec are output to the ECU 50.

The torque converter 20 is connected to the continuously variable transmission 30 and the engine 10 and includes a known lock-up mechanism, and a torque converter with a lock-up clutch that is a power intermittent means that can be coupled and released. It has become. This lockup clutch performs coupling (lockup state) or release (converter state) between the engine 10 and the continuously variable transmission 30. The input shaft 60 of the torque converter 20 is provided with a rotation sensor 21 that detects the rotational speed of the input shaft 60, and the detected input shaft rotational speed N _tc is output to the ECU 50.

  Further, the vehicle is provided with an ECU (electronic control unit) 50 that controls the engine 10, the continuously variable transmission 30, and the like. The ECU 50 includes the engine 10, the torque converter 20, and the continuously variable transmission 30 (hydraulic control). Comprehensive control of the device 40). The ECU 50 includes an input / output device, storage means (ROM, RAM, etc.) for storing a control map, a control program, etc., a CPU (central processing unit), an A / D converter, a D / A converter, a communication driver circuit, and the like. It is configured. The ECU 50 functions as loss torque estimation means, engine torque control means, and shift control means by executing a control program with the CPU.

  Further, the vehicle is provided with an accelerator position sensor 11 that detects the amount of operation of the accelerator pedal (accelerator opening), and the detected accelerator opening is output to the ECU 50. An electronic throttle valve 13 is provided in the intake pipe 12 of the engine 10, and the electronic throttle valve 13 can be opened and closed by a throttle actuator 14. The ECU 50 drives the electronic throttle valve 13 by the throttle actuator 14 and controls the throttle opening so as to correspond to the accelerator opening. A throttle position sensor 15 with an idle switch for detecting the fully closed state (idle state) of the electronic throttle valve 13 and the throttle opening is provided, and the detected idle signal and the throttle opening are output to the ECU 50.

  The intake pipe 12 is provided with an air flow sensor 16 that detects the intake air amount upstream of the electronic throttle valve 13, and the detected intake air amount is output to the ECU 50. Further, the engine 10 is provided with an engine speed sensor 17 for detecting an engine speed (engine speed) and a combustion pressure sensor 18 for detecting a combustion pressure, and the detected engine speed and combustion are detected. The pressure is output to the ECU 50.

  Further, the vehicle is provided with a vehicle speed sensor 51 for detecting the traveling speed of the vehicle and a shift position sensor 52 for detecting the position of the shift lever operated by the driver, and the detected vehicle speed and shift are detected. The position is output to the ECU 50.

  The ECU 50 determines the fuel injection amount, the injection timing, the ignition timing, and the like based on the operating state of the engine 10 such as the engine speed, the intake air amount, and the throttle opening, and controls the injector, the ignition plug, and the like. Further, the ECU 50 has a shift map, determines the gear ratio of the continuously variable transmission 30 based on the throttle opening, the vehicle speed, and the like, and the hydraulic control device 40 so as to establish the determined gear ratio. To control.

In the normal engine torque control, the ECU 50 determines a target throttle opening corresponding to the accelerator opening, and commands the determined target throttle opening to the throttle actuator 14. In response to this, the throttle actuator 14 controls the opening of the electronic throttle valve 13 so that the actual throttle opening matches the target throttle opening. Further, the ECU 50 executes engine compensation torque control in order to reduce a shift shock due to a loss torque due to rotational inertia (a negative inertia torque associated with a change in the gear ratio during a shift) T _loss . In the engine compensation torque control, an engine compensation torque T _egc that compensates (cancels) the loss torque T _loss due to the rotational inertia is calculated, and the target throttle opening corresponding to the accelerator opening is only the opening corresponding to the engine compensation torque T _egc. The target throttle opening increased is commanded to the throttle actuator 14. That is, the engine compensation torque T _egc for reducing the shift shock is calculated, and throttle control is performed to correct the engine torque to reduce the shift shock.

Further, as described above, when the shift is started in a state where the engine output torque T _eg (actual engine torque) is not sufficient, that is, in a state where the loss torque T _loss is larger than the engine output torque T _eg , the vehicle acceleration drops and the acceleration response There is a problem that the sex gets worse. Therefore, in this embodiment, when the engine output torque T _eg becomes larger than the loss torque T _loss due to the rotation inertia, the ECU 50 outputs a shift start command to the hydraulic control device 40 and starts the shift operation. .

  FIG. 2 is a flowchart for explaining control during shifting of the ECU 50, and FIGS. 3 to 6 show timing charts in the control during shifting.

In FIG. 2, the ECU 50 determines whether or not the accelerator is turned on based on the accelerator opening input from the accelerator position sensor 11 (step S1). When the accelerator is turned on (“ Yes "), the loss torque T _loss due to the rotational inertia is estimated based on the speed change condition and the like (step S2). The loss torque T _loss due to rotational inertia can be calculated by the following equation (1), for example.

ω ₁ , ω ₂ , and ω ₃ can be calculated based on the input shaft speed N _tc , the primary speed N _pri , and the secondary speed N _sec , respectively.

Although the loss torque T _loss due to the rotational inertia is calculated by the above formula (1), the present invention is not limited to this, and the difference between the input (engine torque) and the output (drive torque), the drive system The loss torque T _loss due to rotational inertia may be estimated using a model base based on a vehicle model including the above, a map fit based on driving conditions, and the calculation method described in Patent Document 1 described above.

Thereafter, the ECU 50 starts engine compensation torque control (step S3). Specifically, the ECU 50 calculates the engine compensation torque T _egc that compensates (cancels) the loss torque T _loss due to the rotational inertia, and _sets the target throttle opening corresponding to the accelerator opening to the engine compensation torque T _egc. And the increased target throttle opening degree is commanded to the throttle actuator 14. The throttle actuator 14 controls the opening of the electronic throttle valve 13 so that the actual throttle opening matches the target throttle opening. By changing the engine torque by the throttle opening control, the loss torque T _loss due to the rotation inertia can be canceled out, and the shift shock caused by the loss torque T _loss can be reduced.

Next, the ECU 50 determines whether or not engine output torque T _eg (actual engine torque)> loss torque T _loss due to rotational inertia (step S4). Here, the engine output torque T _eg can be estimated based on the combustion pressure input from the combustion pressure sensor 18, for example. Since it is known that the combustion pressure and the engine output torque T _eg have a certain relationship, for example, the current engine output torque T _eg is estimated based on the detected combustion pressure using a conversion formula or a map. be able to.

If engine output torque T _eg > loss torque T _loss due to rotational inertia (“Yes” in step S4), ECU 50 outputs a gear shift start command (gear ratio change command) to hydraulic control device 40 (step S5). ). In response to this, the hydraulic control device 40 starts changing the gear ratio of the continuously variable transmission 30.

The ECU 50 stops the engine compensation torque control (step S7) when the shift is completed (“Yes” in step S6). Thereafter, normal engine torque control is performed.
Here, the engine compensation torque control is stopped at the shift end timing and returned to the normal engine torque control. If the engine compensation torque control is continued after the shift end, a shock may occur at the end of the shift. This is because (see FIG. 3).

  When the torque converter 20 is in the converter state, the torque fluctuation absorbing function does not cause a problem as much as when the shift shock is in the lock-up state. Therefore, the engine compensation torque control may not be executed. Specifically, the ECU 50 determines whether the torque converter 20 is in a lock-up state or a converter state. If the torque converter 20 is in the lock-up state, the ECU 50 executes engine compensation torque control. The normal engine torque control may be performed without executing the above.

Here, changes in various operation amounts in the above-described shift control will be described based on the time charts of FIGS. In the figure, (a) is the accelerator opening, (b) is the engine torque command value (target engine torque), (c) is the engine output torque T _eg (actual engine torque), and (d) is the torque loss due to rotational inertia. T _loss , (e) indicates the shift command value, (f) indicates the vehicle acceleration, the solid line indicates the case where the engine compensation torque control according to this embodiment is performed, and the dotted line indicates the case where the engine compensation torque control is not performed. Yes. Here, the downshift operation accompanying the depression operation of the accelerator pedal by the driver will be described.

  In FIG. 3, first, as shown in FIG. 3A, the target gear ratio increases (at the low speed side) during acceleration in which the driver depresses the accelerator pedal and increases the accelerator opening to increase the engine required load. The continuously variable transmission 30 is downshifted to the increased target gear ratio.

Such a shift causes a change in the engine rotation speed with a change in the gear ratio, and at the time of a downshift to increase the engine rotation speed, the engine output torque T _eg depends on the rotation inertia shown in (d). By being reduced by the loss torque T _loss, a shift shock with a feeling of pulling in torque is generated.

Therefore, in this embodiment, when accelerator ON is detected (t1), engine compensation torque control is performed, and as shown in (b), the engine torque command value (target engine torque) is increased as shown by the solid line, The loss torque T _loss due to inertia is offset. Thereby, the shift shock caused by the loss torque T _loss can be reduced.

Further, when the shift is started in a state where the engine output torque T _eg is not sufficient, the vehicle acceleration decreases as shown by the alternate long and short dash line in (f), and the acceleration responsiveness deteriorates. Therefore, in this embodiment, when engine output torque T _eg > loss torque T _loss due to rotational inertia, as shown in (t2) and (e), shifting is started and engine output torque T _eg is sufficient. Shift in the state. Thereby, the acceleration response can be improved as shown by the solid line in (f). When the shift is completed, the engine compensation torque control is stopped as shown in (t3) and (b). As a result, a shock at the end of shifting can be prevented. In this case, if the torque is suddenly changed, a shock accompanying the sudden torque change may occur. Therefore, as shown in (b), the engine compensation torque control is not stopped instantaneously but is stopped gently. .

  FIG. 4 shows a timing chart in the case where the engine torque is quickly raised at the time of shifting. In the same figure, as shown in (b), when the engine torque is raised quickly, acceleration response can be improved as shown in (f).

FIG. 5 shows a timing chart when the shift speed is increased. In the figure, as shown in (e), when the shift speed is increased, the loss torque T _loss increases as shown in (d). For this reason, as shown in (b), since a large engine compensation torque T _egc is required to compensate for this loss torque T _loss , it is desirable not to increase the shift speed more than necessary.

FIG. 6 shows a timing chart when the engine compensation torque control is stopped and not stopped at the timing of shifting. In the same figure, as indicated by the one-dot chain line in (b), if the engine compensation torque control is not stopped at the timing of the end of the shift, the acceleration due to the reduction in the loss torque T _{loss as} indicated by the one-dot chain line in (f) Change occurs. The driver may feel this acceleration change as a shift shock or an acceleration response delay. Therefore, as shown by the solid line in (b), it is effective to stop the engine compensation torque control at the timing of completion of the shift.

As described above, according to the present embodiment, when the accelerator 50 is detected, the ECU 50 estimates the loss torque T _loss due to the rotational inertia accompanying the shift, and performs the engine compensation torque control for compensating the loss torque T _loss. In addition, when the engine output torque T _eg becomes larger than the loss torque T _loss , the continuously variable transmission 30 is instructed to start shifting. Responsiveness can be improved.

  Further, since the ECU 50 stops the engine compensation torque control and performs the normal engine torque control when the shift of the continuously variable transmission 30 is finished, the acceleration at the end of the gear change accompanying the engine compensation torque control is determined. It becomes possible to prevent shock due to change.

  In the above embodiment, the belt type continuously variable transmission is used as the continuously variable transmission. However, the present invention is not limited to this, and the toroidal continuously variable transmission or the electronic continuously variable transmission is used. Etc. may be used. In the above-described embodiment, the case where the engine torque control is performed by controlling the electronically controlled throttle device (the electronic throttle valve 23 and the throttle actuator 24) has been described. It may be increased or the turbocharger is activated.

  As described above, the speed change control device and speed change control method for a continuously variable transmission according to the present invention are useful for reducing a speed change shock and improving acceleration response at the time of speed change. The present invention is applicable to various continuously variable transmissions such as a transmission, a toroidal continuously variable transmission, and an electronic continuously variable transmission.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a vehicle power train and a control system thereof to which a shift control device and a shift control method for a continuously variable transmission according to an embodiment of the present invention are applied. It is a flowchart for demonstrating the control at the time of the shift by the transmission control apparatus of the continuously variable transmission of a present Example. It is a figure which shows an example of the timing chart at the time of gear shifting. It is a figure which shows an example of the timing chart at the time of gear shifting. It is a figure which shows an example of the timing chart at the time of gear shifting. It is a figure which shows an example of the timing chart at the time of gear shifting.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 11 Accelerator position sensor 12 Intake pipe 13 Electronic throttle valve 14 Throttle actuator 15 Throttle position sensor with idle switch 16 Air flow sensor 17 Engine speed sensor 18 Combustion pressure sensor 20 Torque converter 30 Continuously variable transmission 31 Primary pulley 32 Secondary pulley 33 Belt 34 Primary pulley rotation sensor 35 Secondary pulley rotation sensor 40 Hydraulic control device 50 ECU
51 Vehicle speed sensor 52 Shift position sensor 60, 70, 80 axle 90 Drive wheel

Claims (3)

In a transmission control device for a continuously variable transmission that transmits engine output torque to drive wheels,
Detection means for detecting an accelerator state;
Loss torque estimation means for estimating loss torque due to rotational inertia when accelerator ON is detected by the detection means;
Engine torque control means for starting engine compensation torque control for compensating for loss torque due to rotational inertia estimated by the loss torque estimation means;
Shift control means for instructing the continuously variable transmission to start shifting when the engine output torque is greater than the estimated loss torque due to the rotational inertia;
A transmission control device for a continuously variable transmission.   2. The transmission control device for a continuously variable transmission according to claim 1, wherein the engine torque control means stops the engine compensation torque control when the shift of the continuously variable transmission is completed. In a transmission control method for a continuously variable transmission that transmits engine output torque to drive wheels,
A detection process for detecting the accelerator state;
Loss torque estimation step of estimating loss torque due to rotational inertia when accelerator ON is detected in the detection step;
An engine torque control step for starting engine torque control for compensating for the loss torque due to the estimated rotational inertia;
A shift control step for instructing the continuously variable transmission to start shifting when the engine output torque is greater than the loss torque;
A variable speed control method for a continuously variable transmission.

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