JP2004019875A - Speed-change controller of continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the drivability from being lowered by the engagement and disengagement of a lockup clutch in a V-belt continuously variable transmission. <P>SOLUTION: Based on throttle opening and vehicle speed, a target rotational speed Npri is obtained by a target rotational speed Npri set part 41, and a final target gear ratio Gt is calculated by a final target gear ratio calculation part 42. In a speed-changed speed calculation part 43, a target gear ratio G (n) is obtained as a development process up to a final target gear ratio Gt. On the other hand, based on a throttle opening variation amount, the vehicle speed, and an accelerator depressing speed, a target engine rotation rising width ▵Ne is obtained by a target engine rotation rising width calculation part 44. Then, based on the deviation of a target engine rotational speed Ne* (n) based on the above obtained value and an actual engine rotational speed, a target gear ratio correction amount ▵G is calculated by a target gear ratio correction calculation part 48 to correct a target gear ratio G (n) by ▵G through a correction switch 50 at the times of shift down and lockup off whereby an engine speed is raised. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a shift control device for a continuously variable transmission including a lock-up clutch for a vehicle.
[0002]
[Prior art]
As a continuously variable transmission suitable for vehicles, for example, there is a continuously variable transmission using a V-belt.
In this technique, a V-belt is stretched between a primary pulley connected to the engine and a secondary pulley connected to the axle via a torque converter, and the groove width of the primary pulley is variably controlled by hydraulic pressure.
That is, the primary pulley and the secondary pulley are provided with first and second cylinder chambers, respectively. The second cylinder chamber of the secondary pulley is always supplied with the line pressure, and the first cylinder chamber of the primary pulley is supplied with the line pressure. As the pressure, a hydraulic pressure adjusted by the shift control valve is supplied. During traveling, the groove width of the primary pulley is changed by the oil pressure to the first cylinder chamber, so that the pulley ratio, that is, the gear ratio changes.
[0003]
For the control of the gear ratio, the rotation speed Npri of the primary pulley is set using a map or the like set in advance based on the throttle opening and the vehicle speed. , The final target gear ratio is determined.
On the other hand, the torque converter is locked up in order to reduce fuel consumption in a high-speed running region in a vehicle.
[0004]
[Problems to be solved by the invention]
By the way, when the torque converter is not locked up (lock-up off), the slip between the impeller and the turbine in the torque converter causes a comparison with lock-up (lock-up on) when viewed from the continuously variable transmission side. And the engine speed rises.
For this reason, even if the intended driving state is the same for the driver, the rotation state of the engine will behave differently depending on the presence or absence of lockup, and there is a problem that drivability is impaired.
[0005]
4A and 4B show changes in the accelerator opening, the gear ratio, and the engine speed when the accelerator pedal is depressed from fully closed to half open to accelerate. FIG. 4A shows the lock-up on state, and FIG. 4B shows the lock-up off state. Things.
That is, for example, when the accelerator pedal is depressed for acceleration, a downshift occurs and the speed ratio increases. When the lock-up is on, the rotation (speed) Npri of the primary pulley matches the engine speed Ne, but when the lock-up clutch is off, the engine speed significantly increases as compared to when the lock-up clutch is on. I do. For this reason, the instruction of the engine tachometer differs between when the lockup is on and when the lockup is off, or the engine sound changes, so that the driver feels uncomfortable despite the same operation.
[0006]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a shift control device for a continuously variable transmission that prevents drivability from being reduced by turning on and off a lock-up clutch in view of the above-mentioned problems.
[0007]
[Means for Solving the Problems]
Therefore, the present invention according to claim 1 is a shift control device for a continuously variable transmission including a torque converter with a lock-up clutch between the engine and the engine, and a shift mechanism capable of continuously changing the speed ratio. A target gear ratio setting means for calculating a final target gear ratio based on an operating state, and setting a target gear ratio for each predetermined time interval during shifting to the final target gear ratio; and a target engine for each of the predetermined time intervals. Target engine speed setting means for setting the engine speed, and correction means for correcting the target speed ratio based on a deviation between the target engine speed and the actual engine speed when the lock-up clutch is in the disengaged state. And
[0008]
According to a second aspect of the present invention, the target engine speed setting means includes a target engine speed increase calculating section for calculating a target engine speed increase for each of the predetermined time intervals, and sequentially adds the target engine speed increase to the target engine speed. This is for obtaining the engine speed.
According to a third aspect of the present invention, the target engine speed increase calculation unit calculates the target engine speed increase based on the accelerator pedal depression speed, the throttle opening change amount, and the vehicle speed.
[0009]
According to a fourth aspect of the present invention, the correction means corrects the target gear ratio when the lock-up clutch is in the released state and the shift is downshift.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a block diagram showing a system configuration according to the embodiment.
The transmission mechanism 10 with a V-belt 24 stretched between a primary pulley 16 and a secondary pulley 26 is connected to the engine 1 via a torque converter 12 having a lock-up clutch 11.
The primary pulley 16 forms a V-shaped pulley groove with a fixed conical plate 18 that rotates integrally with the output shaft of the torque converter 12 and a movable conical plate 22 opposed thereto. And a first cylinder chamber 20 for displacing the movable conical plate in the axial direction.
[0011]
The secondary pulley 26 forms a V-shaped pulley groove with a fixed conical plate 30 that rotates integrally with the output shaft to the axle side and a movable conical plate 34 that faces the fixed conical plate 34. The movable conical plate 34 is urged by a return spring (not shown) in a direction to narrow the groove width of the pulley groove, and has a second cylinder chamber 32 that exerts hydraulic pressure on its rear surface to displace the movable conical plate 34 in the axial direction. .
[0012]
The transmission mechanism unit 10 is controlled via a hydraulic control unit 36 based on a command from a CVT control unit 40 as a transmission control unit. The hydraulic control unit 36 adjusts the hydraulic pressure from the hydraulic pump 38 using an internal hydraulic control valve (not shown).
That is, the line pressure is constantly supplied to the second cylinder chamber 32 from the hydraulic control unit 36. The hydraulic control unit 36 further supplies the hydraulic pressure adjusted using the line pressure as the original pressure to the first cylinder chamber 20.
[0013]
While the hydraulic pressure applied to the first cylinder chamber 20 is controlled to change the groove width of the primary pulley 16, the line pressure is supplied to the second cylinder chamber 32 to control the clamping pressure on the V-belt 24 to perform a gear shift. The driving force is transmitted according to the contact friction force between the V belt 24 and the pulleys 16 and 26.
In terms of the number of rotations, when the groove width of the primary pulley 16 is increased and the contact radius of the V-belt 24 is small and the contact radius of the secondary pulley 26 is large, the gear ratio becomes large. The side rotation speed is reduced and output to the axle side. At the reverse pulley ratio Hi, output is at a small gear ratio. During this time, the gear ratio continuously changes according to the contact radius ratio between the primary pulley 16 and the secondary pulley 26.
[0014]
On the other hand, the engine 1 is controlled by an engine control unit 2 (control lines are not shown). The engine control unit 2 is connected to a throttle sensor 4 for detecting an opening of a throttle valve 3 (throttle opening TVO) operated by an accelerator pedal (not shown) and an engine rotation sensor 5.
The engine control unit 2 controls the fuel injection amount and the ignition timing based on the current engine speed Ne from the engine speed sensor 5.
The engine control unit 2 supplies information on the throttle opening TVO to the CVT control unit 40.
[0015]
The CVT control unit 40 is connected to a first rotation speed sensor 6 for detecting an input rotation speed Npri of the primary pulley 16 and a second rotation speed sensor 7 for detecting an output rotation speed Nsec of the secondary pulley 26.
Since the output shaft of the secondary pulley 26 is connected to the axle, the vehicle speed Ns can be obtained from the output rotation speed Nsec of the secondary pulley 26.
[0016]
The CVT control unit 40 performs feedback control of the line pressure based on the normal line pressure characteristics during normal running.
That is, the CVT control unit 40 is based on an engine torque calculated based on the throttle opening TV0 and the engine speed Ne during traveling, in addition to the select position signal from the inhibitor switch 8 attached to a select lever (not shown). Then, the input torque to be input to the transmission mechanism 10 via the torque converter 12 is determined. Then, a command is sent to the hydraulic control unit 36 in order to obtain a necessary line pressure according to the normal line pressure characteristic in accordance with the input torque.
[0017]
The CVT control unit 40 sets a predetermined target value (target Npri rotation) of the input rotation speed (primary rotation) Npri of the primary pulley 16 corresponding to the running state represented by the throttle opening TVO and the vehicle speed Ns. A final target gear ratio (target pulley ratio) Gt is determined based on a ratio between the output speed of the secondary pulley 26 (secondary rotation) Nsec.
[0018]
Further, a target engine rotation increase width ΔNe is calculated according to the throttle opening change amount and the accelerator pedal depressing speed, and a target gear ratio G (n) described later is associated with the target engine rotation speed Ne * based on this. to correct. A command is sent to the hydraulic control unit 36 based on the target gear ratio to control the hydraulic pressure applied to the first cylinder chamber 20.
[0019]
FIG. 2 is a control block diagram for determining and correcting the target speed ratio G in the CVT control unit 40.
First, the target Npri rotation setting section 41 obtains a target Npri rotation from a preset map based on the throttle opening TVO input via the engine control unit 2 and the vehicle speed Ns obtained from the secondary rotation Nsec.
The final target gear ratio calculation unit 42 calculates the final target gear ratio Gt by dividing the target Npri rotation by the secondary rotation Nsec.
[0020]
The next shift speed calculation unit 43 calculates a target gear ratio as a lapse process at every predetermined unit time interval up to the final target gear ratio Gt. The previous target gear ratio G (n−1) in the unit time interval is obtained. The current target gear ratio G (n) is calculated in accordance with the difference between the target gear ratio Gt and the final target gear ratio Gt.
The target Npri rotation setting unit 41, the final target gear ratio calculating unit 42, and the gear speed calculating unit 43 constitute a target gear ratio setting unit in the present invention.
[0021]
On the other hand, a target engine rotation increase width calculation unit 44 is provided. Here, the target engine rotation increase width is calculated based on the vehicle speed Ns and the accelerator pedal depressing speed α according to a map set in advance for each change amount of the throttle opening TVO. Find ΔNe.
Note that the accelerator pedal depression speed is obtained as a change speed of the throttle opening TVO.
When the accelerator pedal depressing speed α is low, the driver's intention to accelerate is considered to be small, and a small value is calculated for the target engine rotation increase width ΔNe. In addition, when the amount of change in the throttle opening TVO is large, the engine speed is so high that the value of the target engine rotation increase width ΔNe decreases to suppress this.
[0022]
The target engine rotation speed ΔNe is added to the previous target engine rotation speed Ne * (n−1) in the unit time interval by the adder 45, and is checked by the upper limiter 46 to obtain the current target engine rotation speed Ne. It enters the subtractor 47 as * (n).
The check by the upper limiter 46 is for preventing an unintended increase in the rotation of the engine.
The subtractor 47 obtains a deviation between the current target engine speed Ne * (n) and the actual engine speed, that is, the engine speed Ne from the engine speed sensor 5.
[0023]
The target gear ratio correction amount calculator 48 calculates a target gear ratio correction amount ΔG based on the deviation between the target engine speed and the actual engine speed, for example, by a PID control method.
The target gear ratio correction amount ΔG is input to the correction unit 51 via the correction switch 50, and corrects the current target gear ratio G (n).
The correction switch 50 is controlled by the switch determination unit 49, and is turned on when a downshift is performed (downshift on) and the lockup off condition is satisfied.
The target engine speed increase calculating section 44 and the adder 45 constitute the target engine speed setting means in the present invention. The subtractor 47, the target gear ratio correction amount calculating section 48, the switch determining section 49, and the correction switch 50 are provided. And the correction unit 51 constitute a correction unit.
[0024]
FIG. 3 is a flowchart showing the flow of the correction during the control.
This flow starts when a shift command is issued based on changes in the throttle opening TVO and the vehicle speed Ns.
First, in step 101, it is determined whether or not the target gear ratio G is in a control region in which correction is to be performed. Here, the switch determination unit 49 checks the type of shift and the state of lock-up. If the downshift is on and the lock-up is off, it is determined that the shift is in the control area to be corrected, and the process proceeds to step 102.
If it is not in the control area, the control according to this flow ends.
[0025]
In step 102, as an initialization operation, the target speed ratio correction amount ΔG for the target speed ratio G (n) is set to 0 (zero), and in the next step 103, the correction switch 50 is turned on.
In step 104, the target engine rotation increase width calculator 44 calculates the target engine rotation increase width ΔNe based on the throttle opening change amount, the vehicle speed, and the accelerator pedal depression speed.
[0026]
In step 105, the target engine speed Ne * (n) is added to the previous target engine speed Ne * (n-1) to calculate the target engine speed Ne * (n).
In the next step 106, a difference between the target engine speed Ne * (n) and the actual engine speed Ne is determined, and in step 107, the target gear ratio correction amount calculator 48 calculates the target gear ratio correction amount ΔG based on the difference. Is calculated.
The transmission mechanism 10 is controlled by the target speed ratio G from the correction unit 51 corrected by the target speed ratio correction amount ΔG.
[0027]
In step 108, it is checked whether or not the shift according to the shift command has been completed. Until the shift is completed, the flow after step 104 is repeated. When the engine 1 reaches a predetermined rotation speed corresponding to the target Npri rotation, it is determined that the shift has been completed, the correction switch 50 is turned off in step 109, and control is performed. finish.
[0028]
The present embodiment is configured as described above, and calculates and sets a predetermined target engine speed increase width ΔNe at the time of gear shifting, and calculates a target speed ratio correction amount ΔG to obtain the target engine speed Ne * (n) based on the target engine speed increase width ΔNe. Calculate and calculate the target gear ratio G (n) as the target gear ratio correction amount when the accelerator pedal is depressed from fully closed to half open, or when the gear type is such that the engine rotation tends to increase, such as kickdown, and when the lockup is off. Since the correction is made by ΔG, the engine speed does not suddenly increase even if the lock-up is off.
When the lock-up is on, the engine 1 and the primary pulley 16 are directly connected, and the engine speed also changes according to the target gear ratio G (n) based on the throttle opening TVO and the vehicle speed Ns. Only the engine 1 does not rotate freely.
Therefore, regardless of whether the lock-up is on or off, in the same type of shift, the rotation state of the engine 1 shows the same behavior, and good drivability is secured.
[0029]
【The invention's effect】
As described above, the present invention provides a shift control device for a continuously variable transmission including a torque converter with a lock-up clutch, which sets a target speed ratio at predetermined time intervals during shifting to a final target speed ratio, The target engine speed is set by the target engine speed setting means, and when the lock-up clutch is in the disengaged state, the target speed ratio is corrected based on the deviation between the target engine speed and the actual engine speed by the correction means. Therefore, good drivability is obtained regardless of whether the lockup is on or off.
[0030]
The target engine speed setting means includes a target engine speed increase calculating section for calculating a target engine speed increase at predetermined time intervals, and sequentially adds the target engine speed increase to obtain a target engine speed. By doing so, it is possible to suppress the increase in the engine rotation, and it is possible to surely make the behavior of the engine rotation at the time of gear shifting without a sense of incongruity.
In particular, by calculating the target engine rotation increase width based on the accelerator pedal depression speed, the throttle opening change amount, and the vehicle speed, it is possible to obtain an appropriate engine rotation increase width according to the shift mode.
[0031]
The target gear ratio is corrected when the lock-up clutch is in the disengaged state and the gear shift is a downshift. Can be well stabilized.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a system configuration according to an embodiment of the present invention.
FIG. 2 is a control block diagram relating to determination and correction of a target gear ratio.
FIG. 3 is a flowchart showing a control flow.
FIG. 4 is an explanatory diagram showing a conventional problem when an accelerator pedal is depressed.
[Explanation of symbols]
Reference Signs List 1 engine 2 engine control unit 3 throttle valve 4 throttle sensor 5 engine rotation sensor 6 first rotation speed sensor 7 second rotation speed sensor 8 inhibitor switch 10 transmission mechanism unit 11 lock-up clutch 12 torque converter 16 primary pulley 18 fixed conical plate 20 First cylinder chamber 22 Movable conical plate 24 V belt 26 Secondary pulley 30 Fixed conical plate 32 Second cylinder chamber 34 Movable conical plate 36 Hydraulic control unit 38 Hydraulic pump 40 CVT control unit 41 Target Npri rotation setting unit 42 Final target gear ratio calculation Unit 43 shift speed calculation unit 44 target engine rotation rise width calculation unit 45 adder 46 upper limiter 47 subtractor 48 target gear ratio correction amount calculation unit 49 switch size Part 50 correction switch 51 correction unit

Claims (4)

A shift control device for a continuously variable transmission including a torque converter with a lock-up clutch between the engine and a speed change mechanism capable of continuously changing a speed ratio,
Target gear ratio setting means for calculating a final target gear ratio based on the operating state, and setting a target gear ratio for each predetermined time interval during shifting to the final target gear ratio;
Target engine speed setting means for setting a target engine speed for each of the predetermined time intervals;
Shift control for the continuously variable transmission, comprising: a correction unit that corrects the target gear ratio based on a difference between the target engine speed and the actual engine speed when the lock-up clutch is in a disengaged state. apparatus. The target engine speed setting means includes a target engine speed increase width calculating unit for calculating a target engine speed increase width for each of the predetermined time intervals, and sequentially calculates the target engine speed increase width to obtain the target engine speed. The shift control device for a continuously variable transmission according to claim 1, wherein: 3. The continuously variable transmission according to claim 2, wherein the target engine speed increase calculating unit calculates the target engine speed increase based on an accelerator pedal depression speed, a throttle opening change amount, and a vehicle speed. Transmission control device. 4. The system according to claim 1, wherein the correction unit corrects the target speed ratio when the lock-up clutch is in a disengaged state and the shift is a downshift. Transmission control device for a step transmission.

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