JP2009208751A - Vehicle driving force control unit having continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately prevent a shock accompanying a driver operation in a vehicle having a continuously variable transmission. <P>SOLUTION: A vehicle driving force control unit obtains a torque difference between an engine output torque and a transmission torque transmitted to wheels, calculates an inertia torque of a transmission mechanism which is varied by that the transmission ratio of the continuously variable transmission is controlled, and controls the variable speed of the continuously variable transmission so that the inertia torque of the transmission mechanism cancels the torque difference. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a driving force control device for a vehicle including a continuously variable transmission such as a V-belt system or a toroidal system.

In a vehicle equipped with a continuously variable transmission, there is a problem that a shock occurs due to a driver's sudden acceleration request or a shift request based on a driver's shift operation in the manual shift mode.
As an invention for reducing or preventing such a shock, there has been conventionally known an invention as described in Patent Document 1, for example.
The shift control device for a continuously variable transmission described in Patent Document 1 performs a sudden shift after it is determined that the vehicle has changed from a driven state to a driven state. As a result, the torque change rate at the time of switching from the driven state to the driving state is alleviated, and a shock is prevented or suppressed.
JP 2001-330132 A

  However, the conventional transmission control device for a continuously variable transmission has the following problems. In other words, the technique described in Patent Document 1 simply performs the sudden shift control after waiting for the vehicle to change from the driven state to the driven state, and therefore vibration due to a change in torque from the driven state to the driven state. And the vibration caused by the shift control may synchronize with each other and a shock may occur.

  The present invention proposes a driving force control device capable of suppressing a shock accompanying a driver's accelerator operation or shift operation in a vehicle including a continuously variable transmission.

For this purpose, the driving force control device for a vehicle according to the present invention is as described in claim 1.
A prime mover that is the driving source of the vehicle,
Drive wheels driven by the output of the prime mover;
A transmission mechanism provided between the prime mover and the drive wheel, and transmitting an output of the prime mover to the drive wheel;
A continuously variable transmission that is part of the transmission mechanism and continuously changes the output of the prime mover;
Shift control means for controlling a gear ratio of the continuously variable transmission;
It has.

The vehicle driving force control device of the present invention further includes:
An inertia torque calculating means for calculating an inertia torque of the transmission mechanism that varies when the transmission gear ratio of the continuously variable transmission is controlled by the shift control means;
Shock reducing means for controlling the output of the prime mover or the speed of the continuously variable transmission based on the calculated inertia torque;
It is characterized by having.

According to the vehicle driving force control apparatus of the present invention, the inertia torque of the transmission mechanism is calculated, and the output of the prime mover or the shift speed of the continuously variable transmission is controlled based on the calculated inertia torque. The output of the prime mover or the speed of the continuously variable transmission can be controlled so as to reduce the inertia torque of the transmission mechanism accompanying the speed change.
In other words, fluctuations in the input torque to the transmission mechanism that occur due to the driver's shift operation are calculated based on the inertia torque of the transmission mechanism, and can be reduced by the output of the prime mover, or input torque to the transmission mechanism that occurs due to the accelerator operation Further, it is possible to reduce the shock generated in the vehicle by controlling the shift speed and reducing the transmission speed by the inertia torque of the transmission mechanism.
Furthermore, it is possible to effectively prevent a shift shock not only when switching from the automatic shift mode to the manual shift mode but also during the reverse switching operation.

Hereinafter, embodiments of the present invention will be described in detail based on examples shown in the drawings.
FIG. 1 is a power train including a vehicle driving force control apparatus according to an embodiment of the present invention.
The engine 1 is an internal combustion engine, and the output can be adjusted by changing the opening of the throttle valve 3 by an accelerator pedal (not shown) operated by the driver.

The continuously variable transmission 2 is a well-known V-belt type continuously variable transmission, and includes a primary pulley 5 that is drive-coupled to the output shaft of the engine 1 via a torque converter 4, a secondary pulley 6 that is aligned with the primary pulley 5, and both A V-belt 7 is provided between the pulleys.
Then, a differential gear device 9 is drivingly coupled to the secondary pulley 6 via a final drive gear set 8, and the left and right wheels 19 are rotationally driven by these.

The speed change operation of the continuously variable transmission 2 is such that, among the flanges forming the V-grooves of the primary pulley 5 and the secondary pulley 6, one movable flange is brought relatively close to the other fixed flange to make the V-groove width The width of the V-groove is increased by narrowing the width of the V-belt 7 by changing the winding diameter of the V-belt 7 around the primary pulley 5 and the secondary pulley 6.
The stroke positions of both movable flanges are determined by the primary pulley pressure Ppri and the secondary pulley pressure Psec from the transmission control hydraulic circuit 10.

  The shift control hydraulic circuit 10 includes a step motor 11 as a shift actuator, and the transmission controller 12 drives the step motor 11 to a step position STP corresponding to a target gear ratio R0, which will be described later. The continuously variable transmission can be performed so that the actual speed ratio matches the target speed ratio R0.

For such shift control, the transmission controller 12 is supplied with a signal from a throttle opening sensor 13 for detecting the throttle opening TVO of the throttle valve 3, and
A signal from the vehicle speed sensor 14 for detecting the vehicle speed VSP;
A signal from an input rotation sensor 15 for detecting a transmission input rotation speed (primary pulley rotation speed) Ni;
A signal from an output rotation sensor 16 for detecting a transmission output rotation speed (secondary pulley rotation speed) No;
A signal from the engine rotation sensor 17 for detecting a rotation speed Rev (which may be a transmission input rotation speed) of the engine 1 which is a transmission input-side rotation speed;
A shift operation signal (shift lever position) from the shift lever 18 for the driver to determine the shift mode of the continuously variable transmission 2 is input.

  As shown, the shift lever 18 includes a parking (P) range position, a reverse travel (R) range position, a neutral (N) range position, an automatic shift (D) range (automatic shift mode) position, and an engine brake. (L) In addition to having the range position in the same row, it also has a manual shift (M) mode position next to the automatic shift (D) range (automatic shift mode) position, and it corresponds when operated to these positions A range signal and a mode signal shall be output.

  While the shift lever 18 is positioned in the automatic transmission mode (automatic transmission (D) range), the transmission controller 12 performs a known continuously variable transmission map defined for the vehicle speed VSP and the target engine speed TRev, for example, FIG. Referring to the planned shift pattern shown by the solid line (in the figure, only the automatic shift line when the throttle opening TVO is 0/8, 3/8, 6/8, 8/8 is shown), the input described above The target engine speed TRev is obtained from the throttle opening TVO (engine load) corresponding to the signal and the vehicle speed VSP, and the target gear ratio R0 is controlled steplessly to achieve this.

In the manual shift (M) mode position, the shift lever 18 is elastically supported between the upshift position (+) and the downshift (−) position, and the driver tilts the shift lever 18 to the upshift position (+). Every time the driver issues an upshift command to a higher manual gear ratio, and every time the driver tilts the shift lever 18 to the downshift (−) position, a downshift command to a lower manual gear ratio. Shall be issued.
For manual shift control that becomes an upshift command or a downshift command, manual shift speeds (M1: manual first speed to M6: manual sixth speed) having a plurality of fixed speed ratios as indicated by broken lines in FIG. In this case, each time an upshift command or a downshift command is manually operated by the driver via the shift lever 18, an upshift or a downshift is sequentially performed between the adjacent manual shift stages M1 to M6, and the corresponding manual shift is performed. The target engine speed TRev is obtained from the vehicle speed VSP based on the shift lines M1 to M6 representing the gears, and the target speed ratio R0 is calculated so that this is achieved.

Hereinafter, the shift control according to the present invention will be described.
In these shift control operations, the transmission controller 12 controls the continuously variable transmission 2 by executing the control program shown in FIG. 3 at regular intervals, for example, 100 ms, based on the input information.

  In step S1, it is determined whether or not an accelerator operation has been performed by the driver. If it is determined that the accelerator operation has not been performed (NO), the control program is exited (RETURN), and the control program continues to step S1 to determine whether the accelerator operation has been performed. If it is determined that the accelerator operation has been performed (YES), the process proceeds to step S2.

In step S2, the actual speed ratio R, the target speed ratio R0 after the speed change, and the engine output torque Te are read, and the timer Timer starts counting.
Here, the actual gear ratio R can be calculated from the division of the detected transmission input rotational speed Ni and the transmission output rotational speed No. The engine output torque Te can be estimated based on the detected engine speed Rev and the throttle opening TVO with reference to an engine performance curve stored in advance.

In the next step S3, it is determined whether the difference between the target speed ratio R0 and the actual speed ratio R is less than the threshold value Rmin or whether the timer Timer being counted is greater than a predetermined threshold value. When at least one of these two conditions is satisfied (YES), the control program is exited (RETURN). This is because the shift shock is so small that it can be ignored if the difference between the target speed ratio R0 and the actual speed ratio R is small. Further, this control is terminated when the count time expires.
On the other hand, when these two conditions are not satisfied (NO), the process proceeds to step S4.

In step S4, the driving torque TENG of the engine 1 and the driving torque TDRV of the wheel 19 which is the actual driving torque are calculated, and the torque difference TDLT is calculated. Similarly, the actual drive torque TDRV is calculated from the actual gear ratio R, the engine output torque Te, and the fixed gear ratio of the transmission mechanism. The fixed transmission gear ratio of the transmission mechanism is determined by the components of the transmission mechanism that drive-couples the engine 1 and the wheels 19 such as the final drive gear set 8 and the differential gear device 9.
In other words, when the driving torque of the wheel 19 changes, the greater the change is, the more a shift shock is input from the wheel contact surface toward the transmission mechanism.

  In the next step S5, it is determined whether or not the absolute value of the torque difference TDLT obtained in step S4 is less than a threshold value. If it is less than the threshold (YES), the control program is exited (RETURN). On the other hand, when it is more than a threshold value (NO), it progresses to step S6.

In step S6, a target value dR / dt of the change in speed ratio time during the shift control is calculated.
The purpose of the calculation is that if the gear ratio of the continuously variable transmission changes suddenly due to the accelerator operation, the inertia in the transmission mechanism is proportional to the inertia of the transmission mechanism and proportional to the change in the gear ratio time during the sudden change. Based on the fact that torque is generated,
This is because the control for canceling the drive torque difference TDLT described above is executed by actively controlling the inertia torque.
Since the inertia torque is a product of the change in the gear ratio time and the inertia of the transmission mechanism, specifically, the calculated value obtained by dividing the driving torque difference TDLT by the transmission system inertia IPT of the power train shown in FIG. The target value for time change is dR / dt.

In the next step S7, it is determined whether or not the target value dR / dt of the gear ratio time change calculated in step S6 is less than the maximum capability Rdotmax of the transmission control hydraulic circuit 10 and the step motor 11.
If the target value dR / dt of the gear ratio time change is less than the maximum capacity Rdotmax (YES), the process proceeds to step S8. If the target value dR / dt of the speed ratio time change is equal to or greater than the maximum capacity Rdotmax (NO), the process proceeds to step S10. move on.

  In step S8, the speed ratio can be changed over time within the range of the capability of the continuously variable transmission 2, so that the target value dR / dt is multiplied by the time interval Δt of this control program to change the speed. The ratio change width ΔR is calculated. Then, the actual transmission ratio R is added to the calculated transmission ratio change width ΔR to obtain the transmission ratio RNEXT at the time of execution of the current control program.

  In the next step S9, a gear ratio command STP is output to the step motor 11 so as to execute the current gear ratio RNEXT obtained in step S8. Further, a Tecorrect execution command to be described later is output to a controller (not shown) of the engine 1. Then, the process returns to step S3.

On the other hand, when the process proceeds from step S7 to step S10 described above, the gear ratio cannot be changed over time within the range of the capacity of the continuously variable transmission 2, so the shortage of inertia torque is compensated by correcting the engine output torque. The process to perform is performed. Specifically, the engine output torque correction value Tecorrect is calculated based on the following equation.
Tecorrect = (dR / dt−Rdotmax) * IPT (1)

  In the next step S11, the speed ratio change width ΔR is calculated by multiplying the maximum speed ratio change rate Rdotmax described above by the fixed time interval Δt of this control program. Further, the actual transmission ratio R is added to the calculated transmission ratio change width ΔR to obtain the transmission ratio RNEXT at the time of execution of the current control program. Then, the process proceeds to step S9.

  In step S9, a gear ratio command STP is output to the step motor 11 so as to execute the current gear ratio RNEXT obtained in step S8. Further, an execution command is output to an engine controller (not shown) so that the engine 1 outputs the engine output torque correction value Tecorrect calculated in step S10. Then, the process returns to step S3. The engine controller controls the engine to output the current output plus the correction value Tecorrect.

  Next, the operation of the present embodiment will be described along the time chart of FIG.

When the accelerator pedal is depressed by the driver's operation at the instant t1, the accelerator pedal stroke is large, and it is determined that the accelerator operation has been performed in step S1. Thereafter, in step S3, a target speed ratio R0 of the automatic transmission 2 corresponding to the accelerator pedal stroke is calculated.
The actual speed ratio R changes with a predetermined speed ratio time change (speed change) Rv1 from the instant t1 to the instant t2.

  When the torque difference between the output torque of the engine 1 and the actual drive torque reaches a predetermined value at the instant t2, it is determined in step S5 that the torque difference has fallen below the threshold value, and in step S6, the torque difference is canceled out. A target value dR / dt of a change in gear ratio time (shift speed) that generates the necessary inertia torque is calculated. In step S7, it is determined that the target value dR / dt is equal to or greater than the maximum capacity Rdotmax. In step S10, an engine output torque correction value Tecorrect is calculated.

  At the instant t3 after a lapse of a predetermined time from the instant t2, the target value dR / dt of the speed ratio time change is controlled to the maximum capacity Rdotmax, and the engine 1 is controlled based on the calculated engine torque correction value Tecorrect.

  The broken line DL1 indicates the actual drive torque when the shift speed control and the engine torque control, which are shock reduction means, are not performed. After the instant t3, the output torque of the engine 1 is greatly exceeded, and a large vibration continues thereafter. This indicates that there is a shock on the vehicle.

  The thick broken line DL2 indicates the actual drive torque when only the shift speed control is performed, and after the instant t3, the actual drive torque exceeding the output torque of the engine 1 is smaller than the broken line DL1, It shows that the shock after the driver's accelerator operation is reduced.

  Further, the thick solid line SL1 indicates the actual drive torque when both the shift speed control and the engine torque control are performed, and the actual drive torque exceeding the output torque of the engine 1 after the instant t3 is the thick broken line DL2. This indicates that the shock after the driver's accelerator operation can be further reduced.

  Next, the case where the driver performs a shift operation in the manual shift (M) mode will be described with reference to FIGS.

  In step S21, whether or not the shift lever 18 is in the manual shift (M) mode position, a shift operation is performed, that is, whether or not the shift lever 18 is tilted to the upshift position (+), and the downshift (−) position. Determine whether or not you have been defeated. If it is determined that the shift operation has not been performed (NO), the control program is exited (RETURN), and the control program continues to step S21 to determine whether or not the shift operation has been performed. If it is determined that a shift operation has been performed (YES), the process proceeds to step S22.

  Steps S22 and S23 are the same as steps S2 and S3 shown in FIG.

  In step S24, a preset gear ratio time change dR / dt when shifting from the actual gear ratio R to the target gear ratio R0 is read.

  Next, in step S25, the inertia IPT1 of the transmission mechanism is read, and the process proceeds to step S26. In step S26, an inertia torque IPT2 is calculated from the speed ratio time change dR / dt and the inertia IPT1 of the transmission mechanism.

  In step S27, an engine output correction torque Tecorrect corresponding to the inertia torque IPT2 calculated in step S26 is calculated, and the process proceeds to step S28. In step S28, a command value obtained by adding the engine output correction torque Tecorrect to the engine output torque Te is illustrated. Not output to the engine controller. Then, the process returns to step S23.

  Next, the operation of this embodiment will be further described with reference to the time chart of FIG.

In FIG. 6, when a shift operation signal is issued that the shift lever 18 in the manual shift (M) mode position is tilted to the downshift (−) position at the instant t1, the target speed ratio R0 is calculated.
In FIG. 6, the gear ratio R changes with a change width ΔR per preset time interval Δt from the instant t1 to the next instant t2, and at the instant t2, the gear ratio R switches to the target gear ratio R0. Then, the shift control ends.

According to the driving force control according to the present embodiment, the engine output torque is changed as shown in the figure, so that the wheel driving torque is from before the start of the shift control (instantaneous t1) to after the end of the shift control (instantaneous t2). As shown by the solid line in FIG. 6, there is no large pulsation, and no shift shock occurs.
For comparison, a conventional example in which the above-described shift control is not executed is indicated by a broken line in FIG.

If the engine output torque Te is determined to be YES in step S7 of FIG. 3, the engine output torque Te ranges over the speed ratio before and after the speed change control (t1 to t2) as shown by the solid line Te in FIG. There is no big change.
On the other hand, if NO is determined in step S7 in FIG. 3, that is, if it is determined that the inertia torque that can be generated by the shift control according to this embodiment is insufficient, Tecorrect is added to the engine output torque Te in step S8 and subsequent steps. From performing the correction,
In FIG. 4, the engine output torque is appropriately changed as indicated by a one-dot chain line.

  Although FIG. 6 shows the operation in shifting from the n-th speed to the (n−1) -speed, the same operation as described above can be obtained even in the operation of switching in the reverse direction.

  By the way, according to the above-described embodiment, the transmission controller 12 corresponding to the output torque estimating means and the transmission torque estimating means obtains the engine output torque estimated value TENG and the actual drive torque TDRV, respectively (step S4 in FIG. 3). The transmission controller 12 corresponding to the torque difference calculation means calculates the torque difference TDLT between the engine output torque estimated value TENG and the actual drive torque TDRV. A transmission controller 12 corresponding to an inertia torque calculating means and a shock reducing means includes an inertia of the transmission mechanism shown in FIG. 1 for drivingly coupling the engine 1 and a wheel (not shown) attached to the differential gear device 9, and a continuously variable transmission. The inertia change generated based on the time change ΔR of the speed ratio R of 2 controls the time change ΔR of the speed ratio R so as to cancel out the torque difference TDLT.

Therefore, the shift shock indicated by hatching in FIGS. 4 and 6 can be preferably eliminated in response to the driver's accelerator operation, and the speed change control can be achieved more quickly than in the prior art in which the speed ratio R is gradually corrected. Can do.
Further, unlike the prior art, it does not perform the sudden shift control after waiting for the vehicle to change from the driven state to the driven state, so the vibration due to the change in torque from the driven state to the driven state and the vibration due to the shift control Are synchronized with each other so that an undesirable shift shock does not occur.

Further, according to the above embodiment, the transmission controller 12 corresponding to the inertia torque calculation means and the shock reduction means also corresponds to the maximum inertia torque calculation means, the comparison means, and the corrected output torque calculation means, and the torque difference TDLT is canceled not only by the inertia torque but also by the output torque correction value Tecorrect of the engine 1 (step S26 in FIG. 5).
Even when the gear ratio immediately before the gear shift and the gear ratio just after the gear shift are greatly different, the gear shift shock can be reliably prevented.

Furthermore, according to the above-described embodiment, the transmission controller 12 corresponding to the maximum inertia torque calculating means, the comparing means, and the corrected output torque calculating means can change the torque difference TDLT to the maximum possible time change Rdotmax of the gear ratio R. From the inertia torque and the output torque correction value Tecorrect of the engine 1 (step S10 in FIG. 3).
Even when the gear ratio immediately before the gear shift and the gear ratio just after the gear shift are particularly large, a gear shift shock can be reliably prevented.

  The above description is merely an example of the present invention, and the present invention can be variously modified without departing from the spirit of the present invention. For example, the driving force control of this embodiment is not only when the gear ratio is suddenly changed by operating the accelerator pedal during the automatic gear shift mode or when the gear ratio is suddenly changed during the manual gear shift mode, but also when the mode is switched. Even so, it can be applied.

1 is a schematic system diagram showing a power train including a vehicle driving force control device according to an embodiment of the present invention, together with a control system thereof. FIG. 2 is a diagram showing a shift pattern used when the transmission controller in FIG. 1 obtains a target engine speed and a target gear ratio in an automatic shift mode together with a case in a manual shift mode. It is a flowchart which shows the program which the transmission controller in FIG. 1 performs. It is a time chart which shows the torque change etc. of the said Example compared with a prior art example. 6 is a flowchart showing a program executed by the transmission controller in FIG. 1 when the driver performs a shift operation in the manual mode according to another embodiment of the present invention. It is a time chart which shows the torque change etc. of the said other Example compared with a prior art example.

Explanation of symbols

1 Engine 2 Continuously Variable Transmission 3 Throttle Valve 4 Torque Converter 5 Primary Pulley 6 Secondary Pulley 7 V Belt 8 Final Drive Gear Set 9 Differential Gear Device
10 Shift control hydraulic circuit
11 Step motor
12 Transmission controller
13 Throttle opening sensor
14 Vehicle speed sensor
15 Input rotation sensor
16 output rotation sensor
17 Engine rotation sensor
18 Shift lever

Claims (4)

A prime mover that is the driving source of the vehicle,
Drive wheels driven by the output of the prime mover;
A transmission mechanism provided between the prime mover and the drive wheel, and transmitting an output of the prime mover to the drive wheel;
A continuously variable transmission that is part of the transmission mechanism and continuously changes the output of the prime mover;
Shift control means for controlling a gear ratio of the continuously variable transmission;
An inertia torque calculating means for calculating an inertia torque of the transmission mechanism that varies when the transmission gear ratio of the continuously variable transmission is controlled by the shift control means;
Shock reducing means for controlling the output of the prime mover or the speed of the continuously variable transmission based on the calculated inertia torque;
A driving force control apparatus for a vehicle, comprising: The vehicle driving force control device comprises:
Output torque estimating means for estimating the torque output by the prime mover;
Transmission torque estimation means for estimating torque transmitted to the drive wheel;
Torque difference calculating means for calculating a difference between each torque estimated by the output torque estimating means and the transmission torque estimating means;
With
The shift control means controls a gear ratio of the continuously variable transmission based on an accelerator opening operated by a driver,
2. The vehicle according to claim 1, wherein the shock reduction unit controls a shift speed of the continuously variable transmission so that the torque difference calculated by the torque difference calculation unit is canceled by the inertia torque. Driving force control device. The vehicle driving force control device comprises:
Maximum inertia torque calculating means for calculating the maximum inertia torque of the transmission mechanism when the shift speed by the shift control means is maximum;
Comparing means for comparing the torque difference calculated by the torque difference calculating means with the maximum inertia torque calculated by the maximum inertia torque calculating means;
A correction output torque calculation means for calculating a correction output torque of the prime mover corresponding to a difference between the torque difference and the maximum inertia torque when the comparison means determines that the torque difference is greater than the maximum inertia torque;
With
2. The driving force control apparatus for a vehicle according to claim 1, wherein the shock reduction means controls the output of the prime mover so as to cancel the inertia torque calculated by the inertia torque calculation means. The shift control means controls a gear ratio of the continuously variable transmission based on a driver's shift operation,
The shock reduction means controls the shift speed of the continuously variable transmission and controls the output of the prime mover so that the inertia torque and the corrected output torque cancel out the torque difference calculated by the torque difference calculation means. The vehicle driving force control apparatus according to claim 2, wherein:

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