JP2011202748A - Lock-up release control method for continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a shock caused by release of lock-up and a difference of the shock depending on a driving state by eliminating effects of an operation by a vehicle driver during deceleration traveling.SOLUTION: In a vehicle including an internal combustion engine and a continuously variable transmission which has a torque converter and a lock-up device and to which driving force of the internal combustion engine is input, during deceleration traveling at low speed executing fuel cut, a loss with respect to the traveling of the vehicle including a mechanical loss of the internal combustion engine during the deceleration traveling at least at predetermined vehicle speed or lower is calculated, and based on basic vehicle weight and a vehicle weight correction value, current vehicle weight is calculated. Based on the obtained loss and the calculated current vehicle weight, estimated deceleration in the non-braking state of the vehicle is calculated, and when the estimated deceleration exceeds reverence deceleration, lock-up by the lock-up device is released. The weight correction value is calculated based on actual deceleration and the estimated deceleration and is updated at predetermined frequency.

Description

  The present invention relates to a lockup release control method for a continuously variable transmission mounted on a vehicle such as an automobile.

  Conventionally, in a continuously variable transmission equipped with a torque converter in order to improve fuel efficiency, the input side of the torque converter connected to the crankshaft of the engine is directly connected to the output side connected to the continuously variable transmission mechanism. One having a lock-up mechanism is known. Such a lockup mechanism is generally operated when the vehicle speed becomes higher than a predetermined vehicle speed, that is, lockup is performed. Also, during deceleration, when the vehicle speed becomes lower than the predetermined vehicle speed, the lock-up that has been performed is released to prevent the engine from stopping.

  For example, in the device described in Patent Document 1, in order to expand the operating range in which fuel cut is performed at the time of deceleration, the load of the auxiliary machine is calculated, and the lock that releases the lock-up according to the calculated load of the auxiliary machine 3 shows a control device that calculates an up-release vehicle speed and releases the lock-up based on the calculated lock-up release vehicle speed.

  However, the vehicle speed at the time of deceleration does not necessarily change due to being influenced only by the load of the auxiliary machine. In this Patent Document 1, although the lockup release vehicle speed is calculated in consideration of the load of the auxiliary machine, other factors that change the vehicle speed during deceleration are not taken into account, so appropriate control is promptly performed. It is difficult to implement.

JP 2004-225879 A

  The present invention pays attention to the above points, and can more accurately estimate the deceleration for determining the lockup release, eliminates the influence of the operation of the vehicle driver at the time of decelerating, and generates a shock caused by the lockup release. Another object of the present invention is to reduce the variation that varies depending on the operating state.

  In other words, the lockup release control method for a continuously variable transmission according to the present invention is a vehicle including an internal combustion engine and a continuously variable transmission that includes a torque converter and a lockup device and that receives a driving force of the internal combustion engine. A continuously variable transmission lockup release control method during low-speed deceleration running with fuel cut, at least for vehicle running including a mechanical loss of an internal combustion engine during decelerating at a predetermined vehicle speed or lower The current vehicle weight is calculated based on the basic vehicle weight and the vehicle weight correction value, and the estimated deceleration in the non-braking state of the vehicle is calculated based on the obtained loss and the calculated current vehicle weight. When the estimated deceleration exceeds the reference deceleration, the lockup is released in the lockup device, and the weight correction value is calculated based on the actual deceleration and the estimated deceleration. And updates at a predetermined frequency and.

  According to such a configuration, by calculating the estimated deceleration in the non-braking state based on the loss and the current vehicle weight, the lockup state is released when the vehicle is decelerating at a low vehicle speed. Thus, it is possible to continue to a vehicle speed at an allowable limit of the shock generated at the time of the occurrence of the shock, and it is possible to suppress the shock and the variation of the shock in releasing the lockup while maintaining the improvement of the fuel consumption.

  The present invention is configured as described above, and calculates the estimated deceleration in the non-braking state based on the loss and the current vehicle weight, so that the lockup is performed when the vehicle is decelerating at a low vehicle speed. The state can be continued up to an allowable vehicle speed at which the shock that occurs when the lockup is released, and the variation of the shock and the shock in the release of the lockup can be suppressed while improving the fuel consumption.

The block diagram which shows the structure of the control system which implements embodiment of this invention. The flowchart which shows the control procedure of the embodiment. The flowchart which shows the control procedure of the embodiment. The flowchart which shows the control procedure of the embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the vehicle, that is, the automobile of this embodiment includes, for example, a spark ignition type multi-cylinder internal combustion engine (hereinafter referred to as an engine) 1 and a continuously variable transmission (hereinafter referred to as CVT) connected to the engine 1. 2) and an electronic control unit 3 for controlling the operation of the engine 1 are mounted. Such a configuration of the automobile itself may be one that is well known in this field.

Various sensors are attached to the engine 1 in order to detect its operating state. Specifically, an idle switch, a water temperature sensor, an O ₂ sensor, a crank angle sensor, and the like (not shown) are provided, as well as a rotation speed sensor 5 that detects the engine speed and an intake pressure sensor 6 that detects the intake pipe pressure. Further, a vehicle speed sensor 7 for detecting the vehicle speed is attached to the vehicle body, for example, on the base end side of the propeller shaft. Brake sensors 9 for detecting the above are respectively attached. As the configuration of each sensor itself in the engine 1 and the vehicle body, those well known in this field may be applied.

  The CVT 2 includes a torque converter 11 having a lock-up device 10 and a continuously variable transmission mechanism 12 using a belt, chain or roller on the output side of the torque converter 11. The lock-up device 10 itself may be known in this field, and controls a lock-up clutch that locks up the input side and the output side of the torque converter 11 and a hydraulic pressure for driving the lock-up clutch. And a lock-up solenoid valve 13. The lock-up device 10 operates the lock-up solenoid valve 13 when the vehicle speed falls within a set vehicle speed range, for example, when traveling at a low speed or traveling at a predetermined speed or higher, and locks the clutch clutch by hydraulic pressure of hydraulic oil. It works by connecting and locks up.

  The electronic control unit 3 is configured around a microcomputer 3a, and includes an input interface 3b, a memory 3c, and an output interface 3d. Signals output from the above-described rotation speed sensor 5, intake pressure sensor 6, vehicle speed sensor 7, accelerator sensor 8, and brake sensor 9 are input to the input interface 3b, and information necessary for operation of the engine 1 is input. . The output interface 3d outputs an injection signal for controlling the fuel injection valve, an ignition signal for the spark plug, a lockup signal for controlling the operation of the lockup solenoid valve 13 of the lockup device 10, and the like. Although not shown, a signal is output to the electronic control unit 3 from a sensor for detecting a gear ratio of the CVT 2 in order to control the CVT 2. As such a configuration for controlling the CVT 2, those widely known in this field can be applied.

  The memory 3c of the electronic control unit 3 stores a program for controlling the operation of the engine 1, a control program for the automatic transmission 2, and various data for them. The lock-up release control program of this embodiment obtains a loss for traveling in a vehicle including a mechanical loss of the internal combustion engine at the time of deceleration traveling at least at a predetermined vehicle speed and based on the basic vehicle weight and the vehicle weight correction value. Calculates the vehicle weight, calculates the estimated deceleration in the non-braking state of the vehicle based on the obtained loss and the calculated current vehicle weight, and locks up when the estimated deceleration exceeds the reference deceleration 10 and is programmed to update the weight correction value at a predetermined frequency by calculating the weight correction value based on the actual deceleration and the estimated deceleration. Hereinafter, the control procedure of this embodiment will be described with reference to FIGS. Note that this automatic transmission control program is executed at a predetermined cycle in a traveling state in which the lockup device 10 is operating, that is, in a lockup state, the vehicle is in a deceleration state without operating the brake pedal, and a fuel cut is being performed. Is executed repeatedly.

  First, in step S1, it is determined whether or not the actual vehicle speed (actual vehicle speed) detected based on the signal output from the vehicle speed sensor 7 is less than the lockup release vehicle speed (LU off vehicle speed). The lockup release vehicle speed may be set to a value widely used in this field. If it is determined that the detected actual vehicle speed is lower than the lockup release vehicle speed, lockup release control (LU off control) is executed in step S2. That is, the energization to the lockup solenoid valve 13 is stopped, and the lockup clutch of the lockup device 10 is disengaged.

  On the other hand, when it is determined that the detected actual vehicle speed is equal to or higher than the lockup release vehicle speed, the actual engine speed (actual engine) detected based on the signal output from the speed sensor 5 in step S3. It is determined whether or not (the number of revolutions) is less than the lockup release revolution number (LU off revolution number). Similar to the lockup release vehicle speed, the lockup release rotational speed may be set to a value widely used in this field. If it is determined that the detected actual engine speed is lower than the lockup release speed, lockup release control (LU off control) is executed in step S2.

  On the other hand, if it is determined that the detected actual vehicle speed is equal to or higher than the lockup release rotational speed, it is determined in step S4 whether the vehicle is in an operating condition that satisfies other lockup release conditions (other LU off conditions) other than the vehicle speed and engine speed. Determine whether. Other lock-up release conditions may be set to conditions widely used in this field. If it is determined that the operation state satisfies other lockup release conditions, the lockup release is executed in step S2. On the other hand, if it is determined that the actual operation state does not satisfy the other lockup release conditions, the absolute value of the estimated deceleration rate α, which will be described later, is calculated as a lockup release reference deceleration (LU off) in step S5. It is determined whether or not the absolute value of the reference deceleration) is exceeded.

  If it is determined in step S5 that the absolute value of the estimated deceleration α exceeds the absolute value of the lockup release reference deceleration (LU off reference deceleration), the lockup release is executed in step S2, and the estimated deceleration is executed. If it is determined that the absolute value of α is equal to or smaller than the absolute value of the lockup release reference deceleration, the energization of the lockup solenoid valve 13 is continued in step S6 and the lockup (LU) state is continued. When the vehicle is running in a non-braking state where the brake pedal is not operated, the lockup release reference deceleration is different from the load on the engine 1 before and after the lockup release by performing the lockup release. It is set based on the deceleration when the shock caused by being the maximum allowable.

  The calculation of the estimated deceleration rate α is executed by calculating based on the mechanical loss of the engine 1 and the automatic transmission 2, the air resistance, the rolling resistance, and the current vehicle weight. A subroutine for calculating the estimated deceleration rate α will be described with reference to FIG.

  First, in step S11, a mechanical loss Te of the engine 1 that constitutes a loss in the vehicle for traveling is calculated. The mechanical loss Te of the engine 1 is calculated by, for example, a map created based on the engine speed based on the value obtained by the adaptation, and those not set in the map are calculated by interpolation calculation. In step S12, an auxiliary machine load Th such as an alternator and a headlight is calculated. In step S13, an air conditioner load Ta of the air conditioner is calculated. Further, in step S14, a CVT mechanical loss Tc in the CVT 12 is calculated. These also constitute a loss, like the mechanical loss Te of the engine 1. This calculation is executed by a map, similar to the mechanical loss Te of the engine 1.

Further, based on the obtained mechanical losses Te and Tc and the loads Th and Ta, in step S15, the total mechanical loss Ttm is calculated by the following equation.
Ttm = (Te + Th + Ta) × CVT total ratio (1)
The CVT total ratio is calculated based on the actual gear ratio of CVT2.

  Next, in step S16, the air resistance La is calculated. In step S17, the current vehicle weight Wn, which is the current vehicle weight, is obtained using the weight correction value Wh obtained from the update routine shown in FIG. The current vehicle weight Wn is determined by correcting the basic vehicle weight by the weight correction value Wh every time the lockup release control program is executed. The basic vehicle weight is, for example, in a state where the user is not in the vehicle. It may be set according to the vehicle weight.

  In step S18, the rolling resistance Lk is calculated using the obtained current vehicle weight Wn. About these air resistance La and rolling resistance Lk, it is computable by the map produced based on the value obtained by adaptation.

  In step S19, a total loss Ttl, which is a loss considering the air resistance La and the rolling resistance Lk, is calculated by adding these three elements to the total mechanical loss Ttm.

  In step S20, the estimated deceleration rate α is calculated by dividing it by the current vehicle weight Wn for which the total loss Ttl has been calculated. Specifically, it is as follows.

To−Ttm = La + Lk−Wn · α (2)
However, To is an engine output.

Here, when fuel cut is in progress, To = 0, so equation (2) is
Wn · α = Ttm + La + Lk (3)
It becomes.

Since Ttl = Ttm + La + Lk, equation (3) becomes
Wn · α = Ttl (4)
Thus, the estimated deceleration rate α is calculated by the following equation.
α = Ttl / Wn (5)

  In step S21, the weight correction value Wh is updated. The update of the weight correction value Wh in step S21 is executed by the update routine shown in FIG.

  First, in step S31, it is determined whether the accelerator pedal is not operated (accelerator off) based on a signal output from the accelerator sensor 8. If it is determined in step S31 that the accelerator pedal is being operated, the execution of this routine is terminated.

  Conversely, if it is determined that the accelerator pedal is not operated, it is determined in step S32 whether or not the brake pedal is not operated (brake off) based on the signal output from the brake sensor 9. If it is determined in step S32 that the brake pedal is being operated, the execution of this routine is terminated.

  On the other hand, if it is determined that the brake pedal is not operated, it is determined in step S33 whether or not the actual vehicle speed is lower than the learned vehicle speed, that is, whether or not the vehicle is decelerating at a predetermined vehicle speed or less. If it is determined in step S33 that the actual vehicle speed is greater than or equal to the learned vehicle speed, the execution of this routine is terminated. If it is determined that the actual vehicle speed is less than the learned vehicle speed, step S34 is performed. The learning vehicle speed is updated when, for example, a condition that the actual vehicle speed is equal to or lower than the set vehicle speed is satisfied.

  In step S34, it is determined whether or not the absolute value of the gradient is less than the learning gradient. For example, the gradient is estimated by estimating the acceleration based on the torque generated by the engine 1, the mechanical loss, and the vehicle weight, and comparing the estimated acceleration with the actual acceleration (actual deceleration). As a result, if it is determined that the absolute value of the gradient is greater than or equal to the learning gradient, the execution of this routine is terminated. The learning gradient is updated when, for example, a condition that the gradient is equal to or less than the set gradient is satisfied. The gradient may be obtained by actually measuring acceleration with an acceleration sensor (G sensor).

  On the other hand, if it is determined that the absolute value of the gradient is less than the learning gradient, the actual deceleration obtained by differentiating the actual vehicle speed exceeds learning deceleration # 1 and learning deceleration # 2 in step S35. It is determined whether or not it falls below. Step S35, step S33, and step S34 determine whether the vehicle is traveling stably on a substantially flat place. As for learning deceleration # 1 and learning deceleration # 2, learning is executed when the respective learning conditions are satisfied.

  In step S35, it is determined whether or not the deceleration exceeds learning deceleration # 1 and falls below learning deceleration # 2. If it is determined that the actual deceleration is less than or equal to learning deceleration # 1 or greater than or equal to learning deceleration # 2, the execution of this routine is terminated. On the other hand, if it is determined that the actual deceleration exceeds the learning deceleration # 1 and is less than the learning deceleration # 2, the difference is calculated by subtracting the estimated deceleration α from the actual deceleration in step S36. Then, the vehicle weight correction value Wh is calculated based on the calculated difference and updated. The vehicle weight correction value Wh updated in step S36 is used for calculation of the current vehicle weight Wn in steps S18 and S20. The vehicle weight correction value Wh takes into account the fluctuating weight of the user, luggage, fuel, etc. who get on the vehicle.

  Therefore, when the fuel cut is executed at the time of decelerating at low speed and the lockup is performed by the lockup device 10 and the condition in step S5 described above is satisfied, the actual vehicle speed becomes the lockup release vehicle speed. Even in a traveling state that does not fall below, by executing the lock-up release, it is possible to suppress as much as possible a shock caused by a load fluctuation when the lock-up is released. In addition, by setting the lockup release reference deceleration as described above, it is possible to continue to the actual vehicle speed that is the limit of shock that can permit the release of the lockup. Thereby, the period which continues a fuel cut becomes long, and a fuel consumption can be improved.

  Further, when the vehicle is decelerated at such a low speed, generally, the CVT 2 performs so-called return control in which the gear ratio is shifted to a higher speed ratio. Therefore, if lockup release is performed during such return control, The lower the vehicle speed, the greater the above-mentioned shock when the lockup is released. However, when the vehicle is decelerated at low speed, the effect of the driver of the vehicle, such as the brake operation, is eliminated, and the lockup is released. Shock and shock variability can be reduced.

  In addition, the vehicle weight correction value can be updated at a high frequency during lock-up and fuel-cut deceleration, so that the accuracy can be improved. Can also be improved significantly.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Continuously variable transmission 3 ... Electronic control unit 10 ... Lock-up device 11 ... Torque converter

Claims (1)

In a vehicle comprising an internal combustion engine and a continuously variable transmission having a torque converter and a lock-up device to which the driving force of the internal combustion engine is input, continuously variable at low speed running with fuel cut A transmission lockup release control method comprising:
Find the amount of loss for traveling in the vehicle including the mechanical loss of the internal combustion engine at the time of decelerating traveling at least at a predetermined vehicle speed,
Calculate the current vehicle weight based on the basic vehicle weight and the vehicle weight correction value,
Calculate the estimated deceleration in the unbraking state of the vehicle based on the obtained loss and the calculated current vehicle weight,
When the estimated deceleration exceeds the reference deceleration, the lockup in the lockup device is released,
A lockup release control method for a continuously variable transmission that calculates a weight correction value based on an actual deceleration and an estimated deceleration and updates the weight correction value at a predetermined frequency.

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