JPH11310062A - Power control device for vehicle with transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the output power of a vehicle and the durability of a transmission mounted on the vehicle. SOLUTION: A power control device for a vehicle, provided with a transmission to which torque is transmitted from a prime mover and by which a speed is changed for output power, includes an inertia torque calculating means (step 3) for finding inertia torque according to the rotational change of a rotating member including a prime mover on the input side with respect to the transmission and an output torque upper limit setting means (step 4) having a value, for which an upper limit value for input torque allowed for the transmission is corrected with the inertia torque, defined as an upper limit value for the output torque of the prime mover.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling the power of a vehicle configured to shift the output of a prime mover such as an engine by a transmission such as a continuously variable transmission.

[0002]

2. Description of the Related Art The running state of a vehicle varies in a variety of ways depending on the conditions of a traveling path, and the driving force required of the vehicle also varies. On the other hand, the torque characteristics of the prime mover mounted on the vehicle are determined by its structure, and do not satisfy all of the requirements according to the running state. For example, an internal combustion engine such as a gasoline engine has a small output torque at a low rotational speed, and therefore cannot meet the required torque at the time of starting. The torque increases. As described above, since the driving force required for the vehicle may not match the output of the prime mover, a general vehicle is configured to increase or decrease the output torque of the prime mover by the transmission.

[0003] By the way, the transmission is composed of many parts, but its size is naturally limited,
The input torque is limited in view of its strength or durability. As an example, a belt-type continuously variable transmission will be described. In this type of transmission, a large number of metal pieces (sometimes referred to as pieces or blocks) are arranged in a ring shape in close contact with each other, and the metal pieces are arranged in a metal belt ( The belt is constituted by holding by a hoop. This belt is wound around an input-side pulley and an output-side pulley formed by a fixed sheave and a movable sheave, respectively, and by changing the groove width of each pulley, the winding radius of the belt is changed. To change the gear ratio. In this case, the transmission of torque is performed by the metal pieces that are in close contact with each other receiving the torque due to the frictional force at the contact surface with the pulley, and pressing the adjacent metal pieces. It does not act directly as tension. However, the reaction force for maintaining the contact pressure between the metal piece and the pulley acts as tension on the hoop,
Since the contact pressure increases as the transmission torque increases, the contact pressure increases as the torque increases. Further, the hoop receives bending stress due to the belt being wound around the pulley and curved, and the tension of the hoop increases accordingly. In this way, the transmission torque is restricted so that the tension acting on the hoop is equal to or less than the allowable stress of the hoop.

Japanese Patent Application Laid-Open No. 4-357358 discloses a device for limiting the engine output in order to improve the durability of a belt in this type of belt-type continuously variable transmission. The device described in this publication is characterized by reducing or limiting the engine output instead of limiting the torque input to the continuously variable transmission by sliding the clutch. Specifically, a state in which the belt is likely to be overloaded is determined from the engine speed and the speed of each pulley on the input / output side, and if it is determined that the belt is overloaded, the output of the engine is reduced. It is configured as follows.

[0005]

In the above-described conventional apparatus, a state in which an overload is likely to be applied to the belt is determined based on the engine speed and the speed of each pulley on the input / output side. If the operation state of the engine or the transmission at the time when the rotation speed is detected continues stably,
The torque input to the transmission can be suppressed so that the durability of the belt does not decrease. However, in a state where a rotation change of a rotating member such as an engine occurs,
In addition to the continuously changing input torque to the transmission,
Since the torque accompanying the change in the rotation speed affects the input torque of the transmission, if the input torque of the transmission is limited based only on the rotation speed of the engine and each pulley, excessive torque may be input to the transmission, Or, conversely, the engine output may be unnecessarily suppressed and the power performance of the vehicle may be reduced.

The present invention has been made in view of the above circumstances and provides a power control device capable of improving the durability of a transmission and improving the power performance of a vehicle. It is intended for.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a transmission of a transmission which takes into account an inertia torque accompanying a rotation change of a rotating member on the input side of the transmission, in addition to an engine torque. The invention is characterized in that the input torque is grasped as input torque, and the maximum value of the engine torque is limited so that the input torque including the inertia torque does not exceed the allowable maximum torque of the transmission.

More specifically, the present invention relates to a power control apparatus for a vehicle having a transmission for transmitting torque from a prime mover to a transmission and for shifting and outputting the transmission with the transmission. Inertia torque calculating means for obtaining an inertia torque due to a change in rotation of a rotating member including the prime mover, and an output torque upper limit of the prime mover obtained by correcting the upper limit of the input torque allowed for the transmission with the inertia torque. Output torque upper limit value setting means.

In the apparatus of the present invention, when there is a request for a running state such as a request to increase or decrease the output of the prime mover, and there is a rotational fluctuation of a rotating member including the prime mover on the input side of the transmission, the rotational speed changes Is calculated. When the rotational speed increases, the inertia torque acts as a so-called resistance. Therefore, a value obtained by adding the inertia torque to the upper limit of the input torque allowed for the transmission is set as the output torque upper limit of the prime mover. Conversely, when the rotational speed decreases, the inertia torque at that time increases the input torque of the transmission. Therefore, in this case, the inertia torque is increased to the upper limit of the input torque allowable for the transmission. The value subtracted from the value is set as the output torque upper limit value of the prime mover. As a result, when the vehicle is accelerating, the output torque upper limit value of the prime mover is increased as compared with the related art, and the power performance of the vehicle is improved. Further, at the time of deceleration, the output torque upper limit value of the prime mover is reduced according to the inertia torque, so that excessive torque is not input to the transmission, and the durability thereof can be improved.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described based on specific examples. First, an example of a drive mechanism of a vehicle to which the present invention is applied will be described. In FIG. 2, an output shaft 2 of a prime mover 1 is connected to a transmission 3. Here, the prime mover 1
Includes various power sources that can be used for vehicles, such as internal combustion engines such as gasoline engines and diesel engines, electric motors such as motors, and devices that combine these internal combustion engines and electric motors.

The prime mover 1 is configured to be electrically controllable, and is provided with an electronic control unit (ECU) 4 mainly composed of a microcomputer for the control. The control device 4 is configured to control at least the output of the prime mover 1, and receives an output shaft rotation speed Ne and an output request signal such as an accelerator opening Acc as data for the control. This output request signal is
The point is that it is a signal for increasing / decreasing the output of the prime mover 1. In the case of the prime mover 1 having an electronic throttle valve in addition to the operation amount signal Acc of the accelerator pedal (not shown) operated by the driver. And an output control signal from a cruise control system (not shown) for maintaining the vehicle speed at a set vehicle speed, and the like.

The transmission 3 is for enabling the prime mover 1 to be kept rotating even when the vehicle is stopped. The transmission 3 transmits the torque by pressing the friction plates against each other. Various clutches, such as a general clutch, a fluid coupling (fluid coupling), a fluid type torque converter, a torque converter having a built-in lock-up clutch, an electromagnetic clutch, a powder clutch, and the like can be used.

The transmission 3 is connected to the input shaft 6 of the transmission 5. The transmission 5 is essentially a mechanism for changing the ratio of the number of rotations of the input shaft 6 and the output shaft 7. The transmission 5 may be a stepped transmission, a continuously variable transmission (belt type or toroidal type, etc.), a manual transmission or an automatic transmission, a constant mesh type or a selective mesh type transmission, etc. Various types and configurations can be adopted accordingly. When a continuously variable transmission is used as the transmission 5, its output shaft 7 is connected to a forward / reverse switching mechanism 8. As the forward / reverse switching mechanism 8,
It is possible to use one having a configuration that switches between forward and reverse by changing the meshing state of the gears, one that mainly includes a planetary gear mechanism, and the like.

In the above drive mechanism, if the output request signal such as the accelerator opening Acc changes, the output of the prime mover 1 is increased or decreased, and if the transmission mechanism 3 is in a state of transmitting torque, the prime mover 1 and the rotation speed of the input-side rotating member such as the transmission mechanism 3 change, and at the same time, the input torque to the transmission 5 changes. On the other hand, the input torque allowed to the transmission 5 is restricted in terms of mechanical strength and durability, so that the input torque of the transmission 5 that changes with controlling the prime mover 1 is allowed. It is controlled not to exceed the value. The control routine shown in FIG. 1 is for setting an output maximum value when an engine (internal combustion engine) is used as the prime mover 1.

The output torque of the engine is determined by the required output amount such as the accelerator opening Acc or the throttle opening and the rotational speed Ne for each specification such as the displacement, and therefore, in the control routine shown in FIG. The engine torque Te is obtained from the accelerator opening Acc and the rotation speed Ne using a prepared map and a function for interpolating the map values.

On the other hand, the engine speed change rate ΔNtr
An is read (step 2). The engine speed change speed ΔNtran is determined by detecting the engine speed at regular intervals and calculating the amount of change in engine speed per unit time from the difference between the detected values. When the transmission 3 is in a so-called fully engaged state and the prime mover 1 and the input shaft 6 of the transmission 5 are substantially integrated, the engine speed change speed ΔNtran is Is the speed of change of the rotation speed of the rotating member on the input side.

Next, the inertia torque Ti on the input side of the transmission 5 is calculated from the rotational speed change speed ΔNtran (step 3). The calculation formula is Ti = I × 2π × ΔNtran / 60
It is. Here, I is the moment of inertia of a rotating member including the engine on the input side of the transmission 5 and can be obtained in advance. Therefore, the function of step 3 corresponds to the inertia torque calculating means in the present invention.

The inertia torque T calculated as described above
i is added to the maximum allowable input torque Tmmax of the transmission 5, and this is set as the engine upper limit torque Temax (step 4). Here, the maximum allowable input torque Tmmax of the transmission 5 is predetermined according to the structure of the transmission 5, and for example, in a belt-type continuously variable transmission, it is almost determined by the strength of the belt. The inertia torque Ti has a positive value if the rotational speed change rate ΔNtran is positive as the rotational speed increases, and conversely, if the rotational speed decreases, the rotational speed change rate ΔNtran becomes negative. Therefore, the engine upper limit torque T
The value of emax is larger when the rotation speed increases than when the rotation speed decreases. Step 4 corresponds to the output torque upper limit value setting means in the present invention.

It is determined whether or not the engine torque Te obtained in step 1 is smaller than the engine upper limit torque Temax (step 5). This step 5
If an affirmative determination is made in step 2, the control returns because the input torque to the transmission 5 does not exceed the maximum allowable value due to the output of the engine at that time. Conversely, if a negative determination is made in step 5, the input torque of the transmission 5 including the inertia torque exceeds the maximum allowable value, so that the engine torque Te becomes the upper limit torque Tem calculated in step 4.
ax is set (step 6). That is, the torque Te determined based on the accelerator opening Acc and the rotation speed Ne is limited to the upper limit torque Temax, and step 6 functions as engine torque limiting means.

FIG. 3 shows a time chart when the above control is performed. T0 while traveling at a predetermined vehicle speed
At this point, the accelerator pedal is depressed, and the accelerator opening Acc
For example, when it becomes full opening or large opening near full opening,
A target rotation speed Net of the engine according to the opening is set. The target rotational speed Net is set as a final rotational speed to be reached and a rotational speed or an increasing gradient of the rotational speed in the course of reaching the rotational speed within a predetermined time. It is shown.

When the rotation speed of the input-side rotating member including the engine increases toward its target rotation speed, the inertia torque Ti based on the above-described inertia moment appears as a positive value, and the engine upper limit torque Temax accordingly increases. , The value without considering the inertia torque (value before time t0 in FIG. 3)
Be larger. Therefore, when the accelerator pedal is fully depressed, the engine torque Te is increased to the upper limit torque Temax. The output is a large transient torque that takes into account the inertia torque due to the rotation change within a range that does not overload the transmission 5, and is a larger torque when the inertia torque is not taken into account.
The driving torque for accelerating the vehicle is also sufficiently large, and the power performance of the vehicle is improved.

When the rotation speed of the rotary member on the input side including the engine reaches the target rotation speed Net, after the time t 1,
Since there is no rotation change, the inertia torque Ti becomes zero. Therefore, the engine upper limit torque Temax is changed to the previous inertia torque T.
i, and the engine torque Te is reduced accordingly. This is a torque corresponding to the maximum input torque allowed for the transmission 5, so that an excessive load is not applied to the transmission 5 and durability is not reduced.

When the accelerator pedal is returned at time t2 and the accelerator opening Acc decreases, the target rotation speed Net corresponding to the opening and the gradient of the change in the rotation speed reaching the target rotation speed within a predetermined time are set. Is done. At that time, the inertia torque Ti is calculated based on the rotation speed change and the inertia moment of the rotary member on the input side including the engine, and the engine upper limit torque Temax is reduced according to the inertia torque Ti. Therefore, if the engine torque Te based on the accelerator opening Acc exceeds the upper limit torque, the actually output torque is limited to the upper limit torque Temax. this is,
The rotation is continued until the time t3 when the target rotation speed Net is reached, that is, while the rotation speed is changed. Therefore, the engine torque is reduced as compared with the case where the inertia torque is not taken into account, and accordingly the input torque of the transmission 5 is maintained at the allowable maximum value. With this, the durability is prevented from being reduced.

In the above specific example, the case where the rotational speed changes based on the signal accompanying the operation of the accelerator pedal has been described. However, for example, the throttle opening degree such as cruise control and the output of the prime mover are electrically controlled. Even when the control is performed, a change in the number of revolutions on the input side of the transmission occurs. Therefore, such a vehicle may be controlled in the same manner as in the above-described specific example. Further, in the above specific example, the control has been described in the case where there is a shift accompanying a change in the accelerator opening and a change in the number of revolutions on the input side due to the change. The present invention can also be applied to a case where the rotational speed of the input side of the transmission is increased or decreased accordingly. That is, the change in the number of revolutions on the input side in the present invention is not limited to the change in output from the prime mover. Furthermore, the present invention can also be applied to a power control device for a vehicle having an internal combustion engine and an electric motor.In this case, the output of the electric motor is used to maintain the output of the internal combustion engine at a constant level, and the driving force is increased. In some cases, the output torque of at least one of the electric motor and the internal combustion engine may be controlled in the so-called assist traveling mode.

[0025]

As described above, according to the present invention, in consideration of the fact that the input torque of the transmission increases or decreases due to the change in the rotational speed of the input-side rotary member of the transmission, the rotation of the rotary member is considered. Since the upper limit value of the output torque of the prime mover is increased or decreased according to the inertia torque resulting from the number change, the output torque of the prime mover is unnecessarily limited as compared to a case where the inertia torque is not considered, or On the other hand, it is possible to prevent the size from being excessively increased, and as a result, it is possible to improve the power performance such as the acceleration force of the vehicle and to improve the durability of the transmission.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an example of control of an engine upper limit torque by the device of the present invention.

FIG. 2 is a block diagram schematically illustrating an example of a drive mechanism to which the present invention can be applied.

FIG. 3 is a time chart when the control shown in FIG. 1 is performed.

[Explanation of symbols]

 1 ... prime mover, 3 ... transmission mechanism, 5 ... transmission.

Claims (1)

[Claims] 1. A power control apparatus for a vehicle having a transmission that transmits torque from a prime mover to a transmission and outputs a gear by shifting the transmission, the rotating member including the prime mover on the input side to the transmission. Inertia torque calculating means for obtaining an inertia torque due to a change in rotation of the motor; and output torque upper limit value setting means for setting a value obtained by correcting an upper limit value of an input torque allowed for the transmission by the inertia torque to an output torque upper limit value of the prime mover. And a power control device for a vehicle including a transmission.