JPH11270375A - Control device for vehicle furnished with continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reduce longitudinal vibration at the time of shifting as well as to favorably carry out responsiveness to an output changing demand of a motive power source. SOLUTION: This control device is furnished with a continuously variable transmission connected to the output side of a motive power source, and it is furnished with a means to find total torque applied on a motive power transmission system at the time of shifting (step 2) and a means to output an instruction to start output control of the motive power source to restrain vehicle longitudinal vibration in cases where a variable of the total torque exceeds a previously specified standard value (steps 5, 8). Additionally, it is possible to further furnish a means to decide output a controlled variable of the motive power source in accordance with the found total torque.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a vehicle provided with a continuously variable transmission capable of continuously changing a gear ratio, and more particularly, to suppressing a longitudinal vibration of the vehicle which is expected to occur at the end of a shift. The present invention relates to a device for performing control.

[0002]

2. Description of the Related Art Recently, a continuously variable transmission has been used as a transmission for a vehicle. This type of continuously variable transmission is configured to continuously change the gear ratio by changing the groove width between the input side pulley and the output side pulley around which the belt is wound, that is, the belt winding radius. Or by inclining the power rollers sandwiched between the input side disk and the output side disk each having a toroidal surface to change the radius of the contact position of the power roller with each disk, thereby changing the gear ratio. It is configured to change continuously. The gear ratio is determined by, for example, an accelerator pedal depression angle (accelerator opening) signal indicating a driver's output request, an output request signal from a cruise control that maintains the vehicle speed at a constant vehicle speed, and a vehicle speed. It is controlled based on the running state of the vehicle.

Therefore, when there is an acceleration request due to depression of an accelerator pedal or the like, the gear ratio is controlled to be increased. This is because, in a belt-type continuously variable transmission, the width of the belt on the input side pulley is increased to gradually reduce the winding radius of the belt, and at the same time, the width of the output side pulley is reduced to reduce the belt winding radius. Is performed by increasing. Further, the gear ratio finally set at that time is determined based on the target rotation speed of the prime mover, the vehicle speed, and the like which are determined based on the degree of the output increase request. In the case of such a so-called power-on downshift, inevitable torsion occurs in a power transmission system such as a propeller shaft, and the number of revolutions increases at a predetermined rate. At the end of the reached shift, the torsional torque or the inertia torque may cause a drive torque thrust (overshoot) and a longitudinal vibration (shake) of the vehicle.

In order to prevent or suppress the longitudinal vibration of the vehicle at the end of the shift, it is effective to change the change in the driving torque associated with the shift immediately before the end of the shift. No. 8-177997. The device described in this publication is configured to temporarily reduce the speed ratio immediately before the end of the speed change for increasing the speed ratio. That is, in this device, the time when the speed ratio reaches the target speed ratio and the half cycle of the vehicle longitudinal vibration at the target speed ratio are predicted, and the correction start time of the speed ratio is determined based on the prediction result. At this point, the gear ratio is corrected to the higher vehicle speed side to change the tendency of the drive torque to increase.

[0005]

The longitudinal vibration during shifting of a vehicle equipped with a continuously variable transmission is essentially caused by a sudden torque fluctuation. Therefore, in the above-described conventional device, the speed ratio is temporarily reduced at the end of the speed change in which the speed ratio is increased, whereby the change in torque is smoothed and the longitudinal vibration is suppressed. Such suppression of longitudinal vibration by controlling the gear ratio or the gear speed is often limited to the end of gear shifting due to demands such as to prevent delays in gear shifting. Therefore, when the accelerator pedal is operated suddenly and greatly, a change in the output torque of the power source such as the engine and a change in the torque accompanying the change in the gear ratio occur simultaneously, which may cause longitudinal vibration. There is.

The apparatus described in the above-mentioned publication cannot effectively cope with such longitudinal vibration of the vehicle at the beginning of the shift. Therefore, it is conceivable to control the output of a power source such as an engine output at the time of a gear shift accompanying a request to change the output, thereby preventing a sudden change in torque and longitudinal vibration caused by the change. However, if the output control for suppressing the longitudinal vibration of the vehicle is executed every time an output change request is made due to an accelerator operation, etc., the output of the power source always changes slowly, and the acceleration or deceleration or the response to the accelerator operation is reduced. There is an inconvenience that the properties are reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a control device capable of preventing vehicle longitudinal vibrations at the beginning of a gear shift and having good responsiveness or followability to an output change request. It is intended to do so.

[0008]

In order to achieve the above object, the invention according to the first aspect comprises a continuously variable transmission in which a continuously variable transmission is connected to an output side of a power source. Means for determining the total torque applied to the power transmission system during shifting, and a power source for suppressing vehicle longitudinal vibration when the amount of change in the total torque exceeds a predetermined reference value. Means for outputting an instruction to start output control.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, a means for determining an output control amount of the power source based on the obtained total torque is further provided. It is a feature.

Therefore, in the first aspect of the present invention, when the amount of change in the total torque applied to the power transmission system during the speed change exceeds a reference value, the output control of the power source for suppressing the longitudinal vibration accompanying the speed change is performed. become. Therefore, when the total torque applied to the power transmission system greatly changes even at the beginning of the shift, the output control of the power source is executed and the amount of change in the total torque is suppressed. It is prevented or reduced, and the ride comfort can be maintained in a good state. Conversely, when the amount of change in the total torque applied to the power transmission system is small, for example, when the accelerator operation amount is small, the output of the power source is not controlled so as to suppress the vehicle longitudinal vibration, so the accelerator operation or The output of the power source according to the output demand is maintained. As a result, the response to the acceleration / deceleration request is improved.

According to the second aspect of the present invention, the total torque applied to the power transmission system at the time of the shift is reflected in the output control of the power source for suppressing the longitudinal vibration of the vehicle due to the shift, so that when the shift is started, , And the control of the output torque for suppressing the longitudinal vibration becomes more accurate. as a result,
The longitudinal vibration of the vehicle at the time of shifting can be effectively suppressed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described based on specific examples. First, an example of a power transmission system 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 a vehicle, such as an internal combustion engine such as a gasoline engine or a diesel engine, or an electric motor such as a motor, or a device combining the internal combustion engine and the electric motor. In the following description, the prime mover 1
An example in which an engine is adopted will be described.

The engine 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 engine 1, and an output request signal such as an output shaft rotation speed Ne and an accelerator opening Acc is input as data for the control. This output request signal is a signal for increasing / decreasing the output of the engine 1, and is an accelerator pedal (not shown) operated by the driver.
In the case of the engine 1 provided with an electronic throttle valve in addition to the operation amount signal Acc of the first embodiment, an opening control signal of the electronic throttle valve, a cruise control system (not shown) for maintaining the vehicle speed at a set vehicle speed, and the like. Output request signal from the PC.

Further, the transmission 3 is for enabling the engine 1 to be kept rotating even when the vehicle is at a standstill, and transmits the torque by pressing the friction plates against each other. Various types of 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 employed.

The transmission 3 is connected to a forward / reverse switching mechanism 5. This is provided because a continuously variable transmission 6, which will be described later, cannot invert and output the input.
The forward / reverse switching mechanism 5 includes, for example, a 3
A mechanism having one rotating element, wherein one of the rotating elements is connected to the transmission 3 to be an input element, and the other one is a fixed element that is selectively fixed,
The remaining one rotation element is an output element. By fixing the fixed element by a brake mechanism or the like, the output element rotates in the opposite direction with respect to the input element, and by releasing the fixed element and connecting any two rotating elements integrally. , As a whole, and the input is output as it is.

The continuously variable transmission 6 connected to the forward / reverse switching mechanism 5 will be described. The point of the continuously variable transmission 6 is that the speed ratio of the input shaft 7 and the output shaft 8 is continuously adjusted. This is a mechanism for changing, specifically, an appropriate type of continuously variable transmission such as a belt type or a toroidal type. An electronic control unit (ECU) 9 for electrically controlling the gear ratio is provided. The electronic control unit 9 is connected to the electronic control unit 4 for the engine 1 so as to be able to perform data communication, and receives data necessary for controlling the gear ratio.

An output shaft 8 of the continuously variable transmission 6 is connected to a final reduction gear (differential gear) 10.
The differential gear 10 distributes torque to the right and left wheels while allowing differential rotation of the wheels.

The control device of the present invention for a vehicle having the above-described power transmission system performs the determination as to whether or not to control the engine output to suppress the longitudinal vibration of the vehicle during shifting as described below. . FIG. 1 is a flowchart for explaining the determination process, and the routine shown in FIG. 1 is repeated at predetermined short intervals.

First, the engine speed change speed ΔNe and the target engine torque Teo are read (step 1).
Here, the engine speed change speed ΔNe is essentially the amount of change in the engine speed per unit time. The engine speed is detected every predetermined time, and the difference between the detected values is detected at the detection time interval. Can be obtained by dividing. Further, the target engine torque Teo is determined by an accelerator pedal (not shown).
Is the engine output torque according to the acceleration / deceleration request by operating the accelerator, and the amount of operation of the accelerator pedal (accelerator opening)
Or an output request signal corresponding thereto and the vehicle speed at that time, and the like.For example, the output request amount and the vehicle speed are determined in advance as map values using the parameters as parameters,
What is necessary is just to obtain from the map.

Next, the total torque Ta applied to the power transmission system at the time of shifting is calculated (step 2). The total torque Ta is a torque in consideration of an inertia torque accompanying a rotation change of a rotary member constituting the power transmission system, and corresponds to an actual torque of the power transmission system. As an example of the calculation formula, the total torque Ta is as follows: Ta = Teo−I · 2π · ΔNe / 60. Here, I is the moment of inertia of the power transmission system, and specifically, the engine speed change rate Δ
All of the rotating bodies whose rotational speed changes with Ne, such as the engine 1, a torque converter with a lock-up clutch engaged, a sheave on the input side of the continuously variable transmission 6, and other members that rotate integrally with the engine 1. This is the total inertia torque. Since the engine speed change speed Ne becomes a positive value when the engine output is increased and the vehicle is accelerated, the total torque Ta becomes a value obtained by subtracting the inertia torque from the target engine torque Teo, and conversely, decelerates. In this case, since the engine rotation change speed becomes a negative value, the total torque Ta becomes a value obtained by adding the inertia torque to the target engine torque Teo.

The total torque Ta in step 2 is calculated every time the routine shown in FIG. 1 is performed. In step 3, the total torque Ta calculated this time and the total torque Tab calculated in the previous calculation are calculated. The absolute value of the deviation ΔTa (=
| Ta−Tab |) is obtained. Since the deviation ΔTa of the total torque Ta is a change amount of the total torque Ta at every execution interval time of the routine of FIG. 1, it represents a change gradient or a change rate of the total torque Ta.

The total torque change ΔT thus determined
It is determined whether or not a is equal to or greater than a predetermined reference value α (step 4). This reference value α is a value used as a criterion for judging whether or not the variation ΔTa of the total torque Ta applied to the power transmission system is large enough to induce a vehicle longitudinal vibration exceeding an allowable range. Alternatively, it can be determined in advance based on a required specification or the like. If an affirmative determination is made in step 4, that is, if the variation ΔTa of the total torque Ta is equal to or greater than the reference value α, the flag Fse is set to “1” (step 5). This flag Fse
Is a flag for instructing to start engine torque control for suppressing vehicle longitudinal vibration (shake), and when set to “1”, instructing to execute the engine torque control. On the other hand, when it is set to "0", it is configured to instruct not to execute the engine torque control.

Continuing from step 5, the total torque change Δ
Ta is stored as the latest stored value ΔTab (step 6). The stored value ΔTab is used for controlling engine torque for suppressing longitudinal vibration. That is, the set value of the flag Fse and the storage value ΔTab are read in an engine torque control routine (not shown), and when it is determined that the engine torque control for suppressing longitudinal vibration is to be executed, the engine torque is reduced. The control value is determined based on the total torque change amount ΔTab. The longitudinal vibration suppression control based on the engine torque is executed, for example, by limiting the range of change (change gradient) of the engine torque.
The total torque change amount ΔTab is employed as one of the factors in determining the value of the change width (change gradient) of the engine torque. This type of engine torque control for suppressing vehicle longitudinal vibration is performed by the electronic control unit 4 described above.

Such control of the engine torque is carried out both at the start of the shift and during the longitudinal vibration suppression control after the start of the shift. As a result, not only can the vehicle longitudinal vibration at the start of shifting be effectively suppressed, but also if the engine torque becomes relatively excessive or excessive during shifting, the longitudinal vibration can be reduced. Can be suppressed. In particular, when the control of the gear ratio cannot be performed sufficiently and sufficiently due to the low oil temperature in the continuously variable transmission 6, the vehicle longitudinal vibration suppression control is performed by controlling the torque of the engine 1. Therefore, by reflecting the variation ΔTab of the total torque Ta in the engine torque control, the vehicle longitudinal vibration can be more effectively suppressed.

In step 7 following step 6, the total torque Ta applied to the power transmission system is stored as a saved value Tab for calculating the next total torque change amount ΔTa.
If the total torque change amount .DELTA.Ta is smaller than the reference value .alpha., And a negative determination is made in step 4, the flag Fse is set to "0" (step 8), and the process returns through step 7. That is, even if the accelerator pedal is operated and there is a request for changing the engine output, if the amount of change in the total torque Ta is small and there is no longitudinal vibration which causes a deterioration in ride comfort, the request for changing the output is met. Implement engine torque control. Therefore, for the accelerator operation for maintaining the vehicle speed or performing fine adjustment during normal traveling, engine torque control such as that performed for suppressing vehicle longitudinal vibration is not performed, so that the output or the accelerator operation is not generated. Driving force response is improved.

Here, the relationship between the above specific example and the structure of the present invention will be described. The function of the step 2 corresponds to a means for obtaining the total torque applied to the power transmission system in the present invention. The function of step 8 is
This corresponds to a unit that outputs an instruction to start output control of the power source. Further, the electronic control unit 4 for the engine corresponds to the means for determining the output control amount of the power source in the present invention.

It should be noted that the total torque applied to the power transmission system in the present invention is essentially a torque obtained by correcting the output torque of a power source such as an engine by an inertia torque. The output shaft torque of the transmission 6 may be obtained from Ta = (Teo−I · 2π · ΔNe / 60) × R in consideration of the ratio R.
Alternatively, in consideration of the gear ratio Rd of the differential gear 10, the drive shaft torque may be obtained by Ta = (Teo−I · 2π · ΔNe / 60) × R × Rd. Further, the control device according to the present invention can be applied not only to control during acceleration but also to control during deceleration.

As described at the beginning of the description of this specific example, the present invention relates to a vehicle equipped with a power source other than an internal combustion engine and a vehicle equipped with a continuously variable transmission other than a belt-type continuously variable transmission. And the present invention is not limited to the above specific example. Further, in the case of a belt-type continuously variable transmission, the speed of change is controlled by controlling the changing speed of the groove width in the input side and output side pulleys with hydraulic pressure or the like, and in the case of a toroidal type continuously variable transmission, Alternatively, the tilting speed of the power roller may be controlled by hydraulic pressure or the like.

[0029]

As described above, according to the first aspect of the present invention, the output control of the power source for suppressing the longitudinal vibration of the vehicle is executed or executed in accordance with the total torque applied to the power transmission system. As a result, the vehicle longitudinal vibration during gear shifting can be effectively suppressed, and the output or driving force responsiveness to output control operations such as slight accelerator operation that is performed relatively frequently during normal driving is improved. It can be.

According to the second aspect of the present invention, the total torque applied to the power transmission system during the shift is reflected in the output control of the power source for suppressing the longitudinal vibration of the vehicle due to the shift. The control of the output torque at the start of shifting and the output torque for suppressing longitudinal vibration is more accurate, and as a result, the longitudinal vibration of the vehicle at the time of shifting can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of an engine torque control start determination routine for longitudinal vibration suppression by the apparatus of the present invention.

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

[Explanation of symbols]

 1 ... prime mover 4, 9 ... electronic control unit 6 ... transmission

Claims (2)

[Claims] 1. A control device for a vehicle having a continuously variable transmission in which a continuously variable transmission is connected to an output side of a power source, means for determining a total torque applied to a power transmission system at the time of shifting, and the total torque Means for outputting an instruction to start output control of a power source for suppressing vehicle longitudinal vibration when the amount of change exceeds a predetermined reference value. Control device for a vehicle equipped with 2. The vehicle with a continuously variable transmission according to claim 1, further comprising means for determining an output control amount of the power source based on the obtained total torque. Control device.